Nizar N. Zein, MD, FAASLD

On an otherwise pleasant evening during the first week of July 2016, a businessman who was a citizen of the United Arab Emirates visiting Cleveland for medical treatment was falsely accused of links to a terror organization. Officers stormed his hotel with assault rifles and handcuffed and arrested him—all this, apparently, because the man was dressed in traditional Emirati clothing.

See related article

This case highlights a level of complexity in providing medical care to foreigners far beyond language interpreting services and outside the borders of the institution where medical care is provided. In the current issue of the Journal, Cawcutt and Wilson¹ review their experiences in the care of international patients and the unique challenges associated with it.

FROM THE TEMPLE OF AESCULAPIUS TO CLEVELAND CLINIC

In 2015, patients from more than 100 countries traveled to Cleveland seeking care at Cleveland Clinic. But medical travel was part of the practice of medicine long before major US hospitals became destinations for international patients, and it has been refined over the years.

Ancient cultures had a thriving tradition of patients traveling long distances for the best and most advanced medical treatment.^2–4 In ancient Greece, people from all around the Mediterranean came to the city of Epidaurus to be cured in its famous temple of Aesculapius, built as a medical center.

Similarly, early Islamic cultures established a healthcare system that catered to foreigners. A noted example is the Mansuri hospital in Cairo, built in 1248 ce and considered the most advanced hospital of its time. Accommodating nearly 8,000 patients, the Mansuri hospital became a healthcare destination for foreigners regardless of race or religion.^2–4

Europe also had a great tradition of providing medical care to foreign patients. Between the 15th and 17th centuries, belief in the healing power of mineral water led to the establishment of spas and the rise of spa towns, particularly in the south of France near mineral springs. The poor sanitary conditions of Europe at the time may have prompted the interest in the healing effect of mineral spas, but wealthy individuals from all over the world traveled to these destinations, creating local prosperity due to medical tourism.^2–4

The city of Bath, in England, is a great example. In the 1720s, Bath was a popular destination for those traveling for healthcare. It became the first city in England to build a covered sewage system, ahead of London by several years. It also had paved roads, lights, hotels, and restaurants in much greater numbers than other cities in England, a likely result of prosperity associated with medical tourism.

ALL PATIENTS WANT TO BE TREATED WITH RESPECT AND KINDNESS

While medical knowledge and health delivery models have changed over the years, caring for foreign patients is perhaps as old as medicine itself. The central focus of restoring health is certainly not unique to international patients, but understanding their unique needs is important in order to achieve the best outcomes, something that Cawcutt and Wilson highlight well.¹

A number of studies have addressed the question of what patients really want. Responses were surprisingly consistent: they want to be treated with respect and kindness.^5,6 In other words, they want empathy, and this is true of all patients regardless of ethnicity or background. Empathy is a tremendous therapeutic force and can narrow what may look like an unbridgeable gap between patient and physician.^7,8

EMPATHY REQUIRES EFFECTIVE COMMUNICATION

Empathy, though sometimes innate, requires effective communication and shared experiences. Neither of these two requirements is easily achievable in the care of foreign patients.

Communication is hampered by language barriers, although it can be enhanced significantly by language translating services and the work of certified medical interpreters. These often-invisible heroes should be recognized as essential members of the medical team. Their work requires cultural sensitivity and formal training to avoid miscommunication and medical errors. Codes of ethics for medical interpreters include confidentiality, accuracy in conveying the content and spirit of the message, freedom from personal biases, cultural training, and professional boundaries.⁹

TOWARD CULTURAL COMPETENCY

Lack of shared experiences between the foreign patient and care provider is an even greater obstacle to overcome in eliminating any empathy deficit. Shared experiences, whether cultural, religious, or social, help us to see the world through the eyes of the patient.

International patients may differ from us in background, ethnicity, religion, dress, expectations, and other areas. Cultural and religious backgrounds often dictate certain behaviors in the event of critical illness or death. Even in routine and less acute medical care, the background of a foreign patient may lead to logistical quandaries such as the need for same-sex caregivers or a private room.

A paradox currently exists in our efforts to meet patients’ need and desire for empathy. While culturally empathic care is necessary to achieve the best medical outcomes, this topic is not yet part of the curriculum for physicians or other healthcare providers in training. A culturally sensitive institution has many business advantages.¹⁰ Thorough and focused cultural training of medical staff is essential. Shared experiences can potentially be fashioned through a well-designed cultural competency training program to enhance empathy for foreign patients.

A SERVICE-ORIENTED APPROACH

Besides cultural competency and language training, a service-oriented approach to accommodate the needs of medical travelers and their family members is of paramount importance. Many of the complaints and burdens of medical visitors concern services that are not medical in nature, such as daily living necessities. Transportation, religious services, banking, extended-stay facilities, cell phone service, legal services, shopping, dining, and entertainment are among many other living needs for those receiving medical care abroad. These services are inconsistently provided throughout medical institutions in the United States, which provide care to thousands of international patients annually.

Unique challenges of providing medical care to international patients have direct effects on medical outcomes. A population-based cohort study of US-born and foreign-born adults with lung or colorectal cancer suggested disparities in quality and type of care.¹¹ Foreign-born patients reported lower-quality care and were less likely to receive complex cancer treatments recommended by clinical guidelines. The authors proposed that quality of care and outcomes may be improved with greater emphasis on coordination of care and improving communication. Similar findings were reported in foreign-born patients with breast cancer.¹²

‘WHAT WOULD YOU THINK TO BE USED THUS?’

Four hundred years ago, in the play Sir Thomas More (a collaboration between several Elizabethan playwrights),¹³ the title character confronts a mob of anti-immigrant rioters, and in a speech believed to have been written by William Shakespeare (Act 2, Scene 4), asks them to imagine themselves banished to a foreign country and subjected to hostility such as they were meting out:

Empathy for foreigners seeking medical care is not merely an act of kindness; rather, it is a central piece of healing. Medical institutions interested in providing healthcare to this unique group of patients should take these principles into account and carefully examine their ability to deliver compassionate care collectively to local and foreign-born patients alike.

On an otherwise pleasant evening during the first week of July 2016, a businessman who was a citizen of the United Arab Emirates visiting Cleveland for medical treatment was falsely accused of links to a terror organization. Officers stormed his hotel with assault rifles and handcuffed and arrested him—all this, apparently, because the man was dressed in traditional Emirati clothing.

See related article

This case highlights a level of complexity in providing medical care to foreigners far beyond language interpreting services and outside the borders of the institution where medical care is provided. In the current issue of the Journal, Cawcutt and Wilson¹ review their experiences in the care of international patients and the unique challenges associated with it.

FROM THE TEMPLE OF AESCULAPIUS TO CLEVELAND CLINIC

In 2015, patients from more than 100 countries traveled to Cleveland seeking care at Cleveland Clinic. But medical travel was part of the practice of medicine long before major US hospitals became destinations for international patients, and it has been refined over the years.

Ancient cultures had a thriving tradition of patients traveling long distances for the best and most advanced medical treatment.^2–4 In ancient Greece, people from all around the Mediterranean came to the city of Epidaurus to be cured in its famous temple of Aesculapius, built as a medical center.

Similarly, early Islamic cultures established a healthcare system that catered to foreigners. A noted example is the Mansuri hospital in Cairo, built in 1248 ce and considered the most advanced hospital of its time. Accommodating nearly 8,000 patients, the Mansuri hospital became a healthcare destination for foreigners regardless of race or religion.^2–4

Europe also had a great tradition of providing medical care to foreign patients. Between the 15th and 17th centuries, belief in the healing power of mineral water led to the establishment of spas and the rise of spa towns, particularly in the south of France near mineral springs. The poor sanitary conditions of Europe at the time may have prompted the interest in the healing effect of mineral spas, but wealthy individuals from all over the world traveled to these destinations, creating local prosperity due to medical tourism.^2–4

The city of Bath, in England, is a great example. In the 1720s, Bath was a popular destination for those traveling for healthcare. It became the first city in England to build a covered sewage system, ahead of London by several years. It also had paved roads, lights, hotels, and restaurants in much greater numbers than other cities in England, a likely result of prosperity associated with medical tourism.

ALL PATIENTS WANT TO BE TREATED WITH RESPECT AND KINDNESS

While medical knowledge and health delivery models have changed over the years, caring for foreign patients is perhaps as old as medicine itself. The central focus of restoring health is certainly not unique to international patients, but understanding their unique needs is important in order to achieve the best outcomes, something that Cawcutt and Wilson highlight well.¹

A number of studies have addressed the question of what patients really want. Responses were surprisingly consistent: they want to be treated with respect and kindness.^5,6 In other words, they want empathy, and this is true of all patients regardless of ethnicity or background. Empathy is a tremendous therapeutic force and can narrow what may look like an unbridgeable gap between patient and physician.^7,8

EMPATHY REQUIRES EFFECTIVE COMMUNICATION

Empathy, though sometimes innate, requires effective communication and shared experiences. Neither of these two requirements is easily achievable in the care of foreign patients.

Communication is hampered by language barriers, although it can be enhanced significantly by language translating services and the work of certified medical interpreters. These often-invisible heroes should be recognized as essential members of the medical team. Their work requires cultural sensitivity and formal training to avoid miscommunication and medical errors. Codes of ethics for medical interpreters include confidentiality, accuracy in conveying the content and spirit of the message, freedom from personal biases, cultural training, and professional boundaries.⁹

TOWARD CULTURAL COMPETENCY

Lack of shared experiences between the foreign patient and care provider is an even greater obstacle to overcome in eliminating any empathy deficit. Shared experiences, whether cultural, religious, or social, help us to see the world through the eyes of the patient.

International patients may differ from us in background, ethnicity, religion, dress, expectations, and other areas. Cultural and religious backgrounds often dictate certain behaviors in the event of critical illness or death. Even in routine and less acute medical care, the background of a foreign patient may lead to logistical quandaries such as the need for same-sex caregivers or a private room.

A paradox currently exists in our efforts to meet patients’ need and desire for empathy. While culturally empathic care is necessary to achieve the best medical outcomes, this topic is not yet part of the curriculum for physicians or other healthcare providers in training. A culturally sensitive institution has many business advantages.¹⁰ Thorough and focused cultural training of medical staff is essential. Shared experiences can potentially be fashioned through a well-designed cultural competency training program to enhance empathy for foreign patients.

A SERVICE-ORIENTED APPROACH

Besides cultural competency and language training, a service-oriented approach to accommodate the needs of medical travelers and their family members is of paramount importance. Many of the complaints and burdens of medical visitors concern services that are not medical in nature, such as daily living necessities. Transportation, religious services, banking, extended-stay facilities, cell phone service, legal services, shopping, dining, and entertainment are among many other living needs for those receiving medical care abroad. These services are inconsistently provided throughout medical institutions in the United States, which provide care to thousands of international patients annually.

Unique challenges of providing medical care to international patients have direct effects on medical outcomes. A population-based cohort study of US-born and foreign-born adults with lung or colorectal cancer suggested disparities in quality and type of care.¹¹ Foreign-born patients reported lower-quality care and were less likely to receive complex cancer treatments recommended by clinical guidelines. The authors proposed that quality of care and outcomes may be improved with greater emphasis on coordination of care and improving communication. Similar findings were reported in foreign-born patients with breast cancer.¹²

‘WHAT WOULD YOU THINK TO BE USED THUS?’

Four hundred years ago, in the play Sir Thomas More (a collaboration between several Elizabethan playwrights),¹³ the title character confronts a mob of anti-immigrant rioters, and in a speech believed to have been written by William Shakespeare (Act 2, Scene 4), asks them to imagine themselves banished to a foreign country and subjected to hostility such as they were meting out:

Empathy for foreigners seeking medical care is not merely an act of kindness; rather, it is a central piece of healing. Medical institutions interested in providing healthcare to this unique group of patients should take these principles into account and carefully examine their ability to deliver compassionate care collectively to local and foreign-born patients alike.

On an otherwise pleasant evening during the first week of July 2016, a businessman who was a citizen of the United Arab Emirates visiting Cleveland for medical treatment was falsely accused of links to a terror organization. Officers stormed his hotel with assault rifles and handcuffed and arrested him—all this, apparently, because the man was dressed in traditional Emirati clothing.

See related article

This case highlights a level of complexity in providing medical care to foreigners far beyond language interpreting services and outside the borders of the institution where medical care is provided. In the current issue of the Journal, Cawcutt and Wilson¹ review their experiences in the care of international patients and the unique challenges associated with it.

FROM THE TEMPLE OF AESCULAPIUS TO CLEVELAND CLINIC

In 2015, patients from more than 100 countries traveled to Cleveland seeking care at Cleveland Clinic. But medical travel was part of the practice of medicine long before major US hospitals became destinations for international patients, and it has been refined over the years.

Ancient cultures had a thriving tradition of patients traveling long distances for the best and most advanced medical treatment.^2–4 In ancient Greece, people from all around the Mediterranean came to the city of Epidaurus to be cured in its famous temple of Aesculapius, built as a medical center.

Similarly, early Islamic cultures established a healthcare system that catered to foreigners. A noted example is the Mansuri hospital in Cairo, built in 1248 ce and considered the most advanced hospital of its time. Accommodating nearly 8,000 patients, the Mansuri hospital became a healthcare destination for foreigners regardless of race or religion.^2–4

Europe also had a great tradition of providing medical care to foreign patients. Between the 15th and 17th centuries, belief in the healing power of mineral water led to the establishment of spas and the rise of spa towns, particularly in the south of France near mineral springs. The poor sanitary conditions of Europe at the time may have prompted the interest in the healing effect of mineral spas, but wealthy individuals from all over the world traveled to these destinations, creating local prosperity due to medical tourism.^2–4

The city of Bath, in England, is a great example. In the 1720s, Bath was a popular destination for those traveling for healthcare. It became the first city in England to build a covered sewage system, ahead of London by several years. It also had paved roads, lights, hotels, and restaurants in much greater numbers than other cities in England, a likely result of prosperity associated with medical tourism.

ALL PATIENTS WANT TO BE TREATED WITH RESPECT AND KINDNESS

While medical knowledge and health delivery models have changed over the years, caring for foreign patients is perhaps as old as medicine itself. The central focus of restoring health is certainly not unique to international patients, but understanding their unique needs is important in order to achieve the best outcomes, something that Cawcutt and Wilson highlight well.¹

A number of studies have addressed the question of what patients really want. Responses were surprisingly consistent: they want to be treated with respect and kindness.^5,6 In other words, they want empathy, and this is true of all patients regardless of ethnicity or background. Empathy is a tremendous therapeutic force and can narrow what may look like an unbridgeable gap between patient and physician.^7,8

EMPATHY REQUIRES EFFECTIVE COMMUNICATION

Empathy, though sometimes innate, requires effective communication and shared experiences. Neither of these two requirements is easily achievable in the care of foreign patients.

Communication is hampered by language barriers, although it can be enhanced significantly by language translating services and the work of certified medical interpreters. These often-invisible heroes should be recognized as essential members of the medical team. Their work requires cultural sensitivity and formal training to avoid miscommunication and medical errors. Codes of ethics for medical interpreters include confidentiality, accuracy in conveying the content and spirit of the message, freedom from personal biases, cultural training, and professional boundaries.⁹

TOWARD CULTURAL COMPETENCY

Lack of shared experiences between the foreign patient and care provider is an even greater obstacle to overcome in eliminating any empathy deficit. Shared experiences, whether cultural, religious, or social, help us to see the world through the eyes of the patient.

International patients may differ from us in background, ethnicity, religion, dress, expectations, and other areas. Cultural and religious backgrounds often dictate certain behaviors in the event of critical illness or death. Even in routine and less acute medical care, the background of a foreign patient may lead to logistical quandaries such as the need for same-sex caregivers or a private room.

A paradox currently exists in our efforts to meet patients’ need and desire for empathy. While culturally empathic care is necessary to achieve the best medical outcomes, this topic is not yet part of the curriculum for physicians or other healthcare providers in training. A culturally sensitive institution has many business advantages.¹⁰ Thorough and focused cultural training of medical staff is essential. Shared experiences can potentially be fashioned through a well-designed cultural competency training program to enhance empathy for foreign patients.

A SERVICE-ORIENTED APPROACH

Besides cultural competency and language training, a service-oriented approach to accommodate the needs of medical travelers and their family members is of paramount importance. Many of the complaints and burdens of medical visitors concern services that are not medical in nature, such as daily living necessities. Transportation, religious services, banking, extended-stay facilities, cell phone service, legal services, shopping, dining, and entertainment are among many other living needs for those receiving medical care abroad. These services are inconsistently provided throughout medical institutions in the United States, which provide care to thousands of international patients annually.

Unique challenges of providing medical care to international patients have direct effects on medical outcomes. A population-based cohort study of US-born and foreign-born adults with lung or colorectal cancer suggested disparities in quality and type of care.¹¹ Foreign-born patients reported lower-quality care and were less likely to receive complex cancer treatments recommended by clinical guidelines. The authors proposed that quality of care and outcomes may be improved with greater emphasis on coordination of care and improving communication. Similar findings were reported in foreign-born patients with breast cancer.¹²

‘WHAT WOULD YOU THINK TO BE USED THUS?’

Four hundred years ago, in the play Sir Thomas More (a collaboration between several Elizabethan playwrights),¹³ the title character confronts a mob of anti-immigrant rioters, and in a speech believed to have been written by William Shakespeare (Act 2, Scene 4), asks them to imagine themselves banished to a foreign country and subjected to hostility such as they were meting out:

Empathy for foreigners seeking medical care is not merely an act of kindness; rather, it is a central piece of healing. Medical institutions interested in providing healthcare to this unique group of patients should take these principles into account and carefully examine their ability to deliver compassionate care collectively to local and foreign-born patients alike.

In Reply: We thank Dr. Mirrakhimov and colleagues for bringing important questions to our attention.

In terms of the differential diagnosis of cholestatic liver injury, we agree that pathologic processes such choledocholithiasis, cholangitis, primary biliary cirrhosis, and primary sclerosing cholangitis should be generally considered. However, in the case we described, the patient had no abdominal pain or fever, which makes choledocholithiasis or cholangitis very unlikely. Primary biliary cirrhosis and primary sclerosing cholangitis can cause chronic liver disease but should not be considered in the differential diagnosis of acute liver injury (acute hepatitis), such as in the case we described.

We agree that the hemolytic anemia typically seen in patients with Wilson disease is Coombs-negative, and that Coombs testing and a peripheral smear should be performed. Both were negative in our patient.

We also agree with Dr. Mirrakhimov and colleagues that Kayser-Fleischer rings are not necessarily specific for Wilson disease and can be seen in patients with other forms of cholestatic liver disease such as primary biliary cirrhosis. However, Kayser-Fleischer rings are pathognomonic for acute liver failure from Wilson disease. In other words, when Kayser-Fleischer rings are seen in a patient with acute liver failure, the diagnosis is Wilson disease until proven otherwise.

We discussed on page 112 of our article other treatments such as plasmapheresis as adjunctive therapy to bridge patients with acute liver failure secondary to Wilson disease to transplant. However, liver transplant is still the only definitive and potentially curative treatment.

In Reply: We thank Dr. Mirrakhimov and colleagues for bringing important questions to our attention.

In terms of the differential diagnosis of cholestatic liver injury, we agree that pathologic processes such choledocholithiasis, cholangitis, primary biliary cirrhosis, and primary sclerosing cholangitis should be generally considered. However, in the case we described, the patient had no abdominal pain or fever, which makes choledocholithiasis or cholangitis very unlikely. Primary biliary cirrhosis and primary sclerosing cholangitis can cause chronic liver disease but should not be considered in the differential diagnosis of acute liver injury (acute hepatitis), such as in the case we described.

We agree that the hemolytic anemia typically seen in patients with Wilson disease is Coombs-negative, and that Coombs testing and a peripheral smear should be performed. Both were negative in our patient.

We also agree with Dr. Mirrakhimov and colleagues that Kayser-Fleischer rings are not necessarily specific for Wilson disease and can be seen in patients with other forms of cholestatic liver disease such as primary biliary cirrhosis. However, Kayser-Fleischer rings are pathognomonic for acute liver failure from Wilson disease. In other words, when Kayser-Fleischer rings are seen in a patient with acute liver failure, the diagnosis is Wilson disease until proven otherwise.

We discussed on page 112 of our article other treatments such as plasmapheresis as adjunctive therapy to bridge patients with acute liver failure secondary to Wilson disease to transplant. However, liver transplant is still the only definitive and potentially curative treatment.

In Reply: We thank Dr. Mirrakhimov and colleagues for bringing important questions to our attention.

In terms of the differential diagnosis of cholestatic liver injury, we agree that pathologic processes such choledocholithiasis, cholangitis, primary biliary cirrhosis, and primary sclerosing cholangitis should be generally considered. However, in the case we described, the patient had no abdominal pain or fever, which makes choledocholithiasis or cholangitis very unlikely. Primary biliary cirrhosis and primary sclerosing cholangitis can cause chronic liver disease but should not be considered in the differential diagnosis of acute liver injury (acute hepatitis), such as in the case we described.

We agree that the hemolytic anemia typically seen in patients with Wilson disease is Coombs-negative, and that Coombs testing and a peripheral smear should be performed. Both were negative in our patient.

We also agree with Dr. Mirrakhimov and colleagues that Kayser-Fleischer rings are not necessarily specific for Wilson disease and can be seen in patients with other forms of cholestatic liver disease such as primary biliary cirrhosis. However, Kayser-Fleischer rings are pathognomonic for acute liver failure from Wilson disease. In other words, when Kayser-Fleischer rings are seen in a patient with acute liver failure, the diagnosis is Wilson disease until proven otherwise.

We discussed on page 112 of our article other treatments such as plasmapheresis as adjunctive therapy to bridge patients with acute liver failure secondary to Wilson disease to transplant. However, liver transplant is still the only definitive and potentially curative treatment.

A 25-year-old woman presents to the emergency department with a 7-day history of fatigue and nausea. On presentation she denies having abdominal pain, headache, fever, chills, night sweats, vomiting, diarrhea, melena, hematochezia, or weight loss. She recalls changes in the colors of her eyes and darkening urine over the last few days. Her medical history before this is unremarkable. She takes no prescription, over-the-counter, or herbal medications. She works as a librarian and has no occupational toxic exposures. She is single and has one sister with no prior medical history. She denies recent travel, sick contacts, smoking, recreational drug use, or pets at home.

On physical examination, her vital signs are temperature 37.3°C (99.1°F), heart rate 90 beats per minute, blood pressure 125/80 mm Hg, respiration rate 14 per minute, and oxygen saturation 97% on room air. She has icteric sclera and her skin is jaundiced. Cardiac examination is normal. Lungs are clear to auscultation and percussion bilaterally. Her abdomen is soft with no visceromegaly, masses, or tenderness. Extremities are normal with no edema. She is alert and oriented, but she has mild asterixis of the outstretched hands. The neurologic examination is otherwise unremarkable.

The patient’s basic laboratory values are listed in Table 1. Shortly after admission, she develops changes in her mental status, remaining alert but becoming agitated and oriented to person only. In view of her symptoms and laboratory findings, acute liver failure is suspected.

ACUTE LIVER FAILURE

1. The diagnostic criteria for acute liver failure include all of the following except which one?

• Acute elevation of liver biochemical tests
• Presence of preexisting liver disease
• Coagulopathy, defined by an international normalized ratio (INR) of 1.5 or greater
• Encephalopathy
• Duration of symptoms less than 26 weeks

Acute liver failure is defined by acute onset of worsening liver tests, coagulopathy (INR ≥ 1.5), and encephalopathy in patients with no preexisting liver disease and with symptom duration of less than 26 weeks.¹ With a few exceptions, a history of preexisting liver disease negates the diagnosis of acute liver failure. Our patient meets the diagnostic criteria for acute liver failure.

Immediate management

Once acute liver failure is identified or suspected, the next step is to transfer the patient to the intensive care unit for close monitoring of mental status. Serial neurologic evaluations permit early detection of cerebral edema, which is considered the most common cause of death in patients with acute liver failure. Additionally, close monitoring of electrolytes and plasma glucose is necessary since these patients are susceptible to electrolyte disturbances and hypoglycemia.

Patients with acute liver failure are at increased risk of infections and should be routinely screened by obtaining urine and blood cultures.

Gastrointestinal bleeding is not uncommon in patients with acute liver failure and is usually due to gastric stress ulceration. Prophylaxis with a histamine 2 receptor antagonist or proton pump inhibitor should be considered in order to prevent gastrointestinal bleeding.

Treatment with N-acetylcysteine is beneficial, not only in patients with acute liver failure due to acetaminophen overdose, but also in those with acute liver failure from other causes.

CASE CONTINUES:
TRANSFER TO THE INTENSIVE CARE UNIT

The patient, now diagnosed with acute liver failure, is transferred to the intensive care unit. Arterial blood gas measurement shows:

• pH 7.38 (reference range 7.35–7.45)
• Pco₂ 40 mm Hg (36–46)
• Po₂ 97 mm Hg (85–95)
• Hco₃ 22 mmol/L (22–26).

A chest radiograph is obtained and is clear. Computed tomography (CT) of the brain reveals no edema. Transcranial Doppler ultrasonography does not show any intracranial fluid collections.

Blood and urine cultures are negative. Her hemoglobin level remains stable, and she does not develop signs of bleeding. She is started on a proton pump inhibitor for stress ulcer prophylaxis and is empirically given intravenous N-acetylcysteine until the cause of acute liver failure can be determined.

CAUSES OF ACUTE LIVER FAILURE

2. Which of the following can cause acute liver failure?

• Acetaminophen overdose
• Viral hepatitis
• Autoimmune hepatitis
• Wilson disease
• Alcoholic hepatitis

Drug-induced liver injury is the most common cause of acute liver failure in the United States,^2,3 and of all drugs, acetaminophen overdose is the number-one cause. In acetaminophen-induced liver injury, serum aminotransferase levels are usually elevated to more than 1,000 U/L, while serum bilirubin remains normal in the early stages. Antimicrobial agents, antiepileptic drugs, and herbal supplements have also been implicated in acute liver failure. Our patient has denied taking herbal supplements or medications, including over-the-counter ones.

Acute viral hepatitis can explain the patient’s condition. It is a common cause of acute liver failure in the United States.² Hepatitis A and E are more common in developing countries. Other viruses such as cytomegalovirus, Epstein-Barr virus, herpes simplex virus type 1 and 2, and varicella zoster virus can also cause acute liver failure. Serum aminotransferase levels may exceed 1,000 U/L in patients with viral hepatitis.

A young woman presents with acute liver failure: What is the cause? Is her sister at risk?

Autoimmune hepatitis is a rare cause of acute liver failure, but it should be considered in the differential diagnosis, particularly in middle-aged women with autoimmune disorders such as hypothyroidism. Autoimmune hepatitis can cause marked elevation in aminotransferase levels (> 1,000 U/L).

Wilson disease is an autosomal-recessive disease in which there is excessive accumulation of copper in the liver and other organs because of an inherited defect in the biliary excretion of copper. Wilson disease can cause acute liver failure and should be excluded in any patient, particularly if under age 40 with acute onset of unexplained hepatic, neurologic, or psychiatric disease.

Alcoholic hepatitis usually occurs in patients with a long-standing history of heavy alcohol use. As a result, most patients with alcoholic hepatitis have manifestations of chronic liver disease due to alcohol use. Therefore, by definition, it is not a cause of acute liver failure. Additionally, in patients with alcoholic hepatitis, the aspartate aminotransferase (AST) level is elevated but less than 300 IU/mL, and the ratio of AST to alanine aminotransferase (ALT) is usually more than 2.

CASE CONTINUES: FURTHER TESTING

The results of our patient’s serologic tests are shown in Table 2. Other test results:

• Autoimmune markers including antinuclear antibodies, antimitochondrial antibodies, antismooth muscle antibodies, and liver and kidney microsomal antibodies are negative; her immunoglobulin G (IgG) level is normal
• Serum ceruloplasmin 25 mg/dL (normal 21–45)
• Free serum copper 120 µg/dL (normal 8–12)
• Abdominal ultrasonography is unremarkable, with normal liver parenchyma and no intrahepatic or extrahepatic biliary dilatation
• Doppler ultrasonography of the liver shows patent blood vessels.

3. Based on the new data, which of the following statements is correct?

• Hepatitis B is the cause of acute liver failure in this patient
• Herpetic hepatitis cannot be excluded on the basis of the available data
• Wilson disease is most likely the diagnosis, given her elevated free serum copper
• A normal serum ceruloplasmin level is not sufficient to rule out acute liver failure secondary to Wilson disease

Hepatitis B surface antigen and hepatitis B core antibodies were negative in our patient, excluding hepatitis B virus infection. The positive hepatitis B surface antibody indicates prior immunization.

Herpetic hepatitis is an uncommon but important cause of acute liver failure because the mortality rate is high if the patient is not treated early with acyclovir. Fever, elevated aminotransferases, and leukopenia are common with herpetic hepatitis. Fewer than 50% of patients with herpetic hepatitis have vesicular rash.^4,5 The value of antibody serologic testing is limited due to high rates of false-positive and false-negative results. The gold standard diagnostic tests are viral load (detection of viral RNA by polymerase chain reaction), viral staining on liver biopsy, or both. In our patient, herpes simplex virus polymerase chain reaction testing was negative, which makes herpetic hepatitis unlikely.

Wilson disease is a genetic condition in which the ability to excrete copper in the bile is impaired, resulting in accumulation of copper in the hepatocytes. Subsequently, copper is released into the bloodstream and eventually into the urine.

However, copper excretion into the bile is impaired in patients with acute liver failure regardless of the etiology. Therefore, elevated free serum copper and 24-hour urine copper levels are not specific for the diagnosis of acute liver failure secondary to Wilson disease. Moreover, Kayser-Fleischer rings, which represent copper deposition in the limbus of the cornea, may not be apparent in the early stages of Wilson disease.

Wilson disease involves accumulation of copper in the liver and other organs as the result of a genetic defect

Since it is challenging to diagnose Wilson disease in the context of acute liver failure, Korman et al⁶ compared patients with acute liver failure secondary to Wilson disease with patients with acute liver failure secondary to other conditions. They found that alkaline phosphatase levels are frequently decreased in patients with acute liver failure secondary to Wilson disease,⁶ and that a ratio of alkaline phosphatase to total bilirubin of less than 4 is 94% sensitive and 96% specific for the diagnosis.⁶

Hemolysis is common in acute liver failure due to Wilson disease. This leads to disproportionate elevation of AST compared with ALT, since AST is present in red blood cells. Consequently, the ratio of AST to ALT is usually greater than 2.2, which provides a sensitivity of 94% and a specificity of 86% for the diagnosis.⁶ These two ratios together provide 100% sensitivity and 100% specificity for the diagnosis of Wilson disease in the context of acute liver failure.⁶

Ceruloplasmin. Patients with Wilson disease typically have a low ceruloplasmin level. However, because it is an acute-phase reaction protein, ceruloplasmin can be normal or elevated in patients with acute liver failure from Wilson disease.⁶ Therefore, a normal ceruloplasmin level is not sufficient to rule out acute liver failure secondary to Wilson disease.

CASE CONTINUES: A DEFINITIVE DIAGNOSIS

Our patient undergoes further testing, which reveals the following:

• Her 24-hour urinary excretion of copper is 150 µg (reference value < 30)
• Slit-lamp examination is normal and shows no evidence of Kayser-Fleischer rings
• Her ratio of alkaline phosphatase to total bilirubin is 0.77 based on her initial laboratory results (Table 1)
• Her AST-ALT ratio is 3.4.

The diagnosis in our patient is acute liver failure secondary to Wilson disease.

4. What is the most appropriate next step?

• Liver biopsy
• d-penicillamine by mouth
• Trientine by mouth
• Liver transplant
• Plasmapheresis

Liver biopsy. Accumulation of copper in the liver parenchyma in patients with Wilson disease is sporadic. Therefore, qualitative copper staining on liver biopsy can be falsely negative. Quantitative copper measurement in liver tissue is the gold standard for the diagnosis of Wilson disease. However, the test is time-consuming and is not rapidly available in the context of acute liver failure.

Chelating agents such as d-pencillamine and trientine are used to treat the chronic manifestations of Wilson disease but are not useful for acute liver failure secondary to Wilson disease.

Acute liver failure secondary to Wilson disease is life-threatening, and liver transplant is considered the only definitive life-saving therapy.

Therapeutic plasmapheresis has been reported to be a successful adjunctive therapy to bridge patients with acute liver failure secondary to Wilson disease to transplant.⁷ However, liver transplant is still the only definitive treatment.

CASE CONTINUES: THE PATIENT’S SISTER SEEKS CARE

The patient undergoes liver transplantation, with no perioperative or postoperative complications.

The patient’s 18-year-old sister is now seeking medical attention in the outpatient clinic, concerned that she may have Wilson disease. She is otherwise healthy and denies any symptoms or complaints.

5. What is the next step for the patient’s sister?

• Reassurance
• Prophylaxis with trientine
• Check liver enzyme levels, serum ceruloplasmin level, and urine copper, and order a slit-lamp examination
• Genetic testing

Wilson disease can be asymptomatic in its early stages and may be diagnosed incidentally during routine blood tests that reveal abnormal liver enzyme levels. All patients with a confirmed family history of Wilson disease should be screened even if they are asymptomatic. The diagnosis of Wilson disease should be established in first-degree relatives before specific treatment for the relatives is prescribed.

Based on information in Roberts EA, Schilsky ML; American Association for Study of Liver Diseases (AASLD). Diagnosis and treatment of Wilson disease: an update. Hepatology 2008; 7:2089–2111.

The first step in screening a first-degree relative for Wilson disease is to check liver enzyme levels (specifically aminotransferases, alkaline phosphatase, and bilirubin), serum ceruloplasmin level, and 24-hour urine copper, and order an ophthalmologic slit-lamp examination. If any of these tests is abnormal, liver biopsy should be performed for histopathologic evaluation and quantitative copper measurement. Kayser-Fleischer  rings are seen in only 50% of patients with Wilson disease and hepatic involvement, but they are pathognomic. Guidelines⁸ for screening first-degree relatives of Wilson disease patients are shown in Figure 1.

Genetic analysis. ATP7B, the Wilson disease gene, is located on chromosome 13. At least 300 mutations of the gene have been described,² and the most common mutation is present in only 15% to 30% of the Wilson disease population.^8–10 Routine molecular testing of the ATP7B

CASE CONTINUES: WORKUP OF THE PATIENT’S SISTER

The patient’s sister has no symptoms and her physical examination is normal. Slit-lamp examination reveals no evidence of Kayser-Fleischer rings. Her laboratory values, including complete blood counts, complete metabolic panel, and INR, are within normal ranges. Other test results, however, are abnormal:

• Free serum copper level 27 µg/dL (normal 8–12)
• Serum ceruloplasmin 9.0 mg/dL (normal 20–50)
• 24-hour urinary copper excretion 135 µg (normal < 30).

She undergoes liver biopsy for quantitative copper measurement, and the result is very high at 1,118 µg/g dry weight (reference range 10–35). The diagnosis of Wilson disease is established.

TREATING CHRONIC WILSON DISEASE

6. Which of the following is not an appropriate next step for the patient’s sister?

• Tetrathiomolybdate
• d-penicillamine
• Trientine
• Zinc salts
• Prednisone

The goal of medical treatment of chronic Wilson disease is to improve symptoms and prevent progression of the disease.

Chelating agents and zinc salts are the most commonly used medicines in the management of Wilson disease. Chelating agents remove copper from tissue, whereas zinc blocks the intestinal absorption of copper and stimulates the synthesis of endogenous chelators such as metallothioneins. Tetrathiomolybdate is an alternative agent developed to interfere with the distribution of excess body copper to susceptible target sites by reducing free serum copper (Table 3). There are no data to support the use of prednisone in the treatment of Wilson disease.

During treatment with chelating agents, 24-hour urinary excretion of copper is routinely monitored to determine the efficacy of therapy and adherence to treatment. Once de-coppering is achieved, as evidenced by a normalization of 24-hour urine copper excretion, the chelating agent can be switched to zinc salts to prevent intestinal absorption of copper.

Clinical and biochemical stabilization is achieved typically within 2 to 6 months of the initial treatment with chelating agents.⁸ Organ meats, nuts, shellfish, and chocolate are rich in copper and should be avoided.

The patient’s sister is started on trientine 250 mg orally three times daily on an empty stomach at least 1 hour before meals. Treatment is monitored by following 24-hour urine copper measurement. A 24-hour urine copper measurement at 3 months after starting treatment has increased from 54 at baseline to 350 µg, which indicates that the copper is being removed from tissues. The plan is for early substitution of zinc for long-term maintenance once de-coppering is completed.

KEY POINTS

• Acute liver failure is severe acute liver injury characterized by coagulopathy (INR ≥ 1.5) and encephalopathy in a patient with no preexisting liver disease and with duration of symptoms less than 26 weeks.
• Acute liver failure secondary to Wilson disease is uncommon but should be excluded, particularly in young patients.
• The diagnosis of Wilson disease in the setting of acute liver failure is challenging because the serum ceruloplasmin level may be normal in acute liver failure secondary to Wilson disease, and free serum copper and 24-hour urine copper are usually elevated in all acute liver failure patients regardless of the etiology.
• A ratio of alkaline phosphatase to total bilirubin of less than 4 plus an AST-ALT ratio greater than 2.2 in a patient with acute liver failure should be regarded as Wilson disease until proven otherwise (Figure 2).
• Acute liver failure secondary to Wilson disease is usually fatal, and emergency liver transplant is a life-saving procedure.
• Screening of first-degree relatives of Wilson disease patients should include a history and physical examination, liver enzyme tests, complete blood cell count, serum ceruloplasmin level, serum free copper level, slit-lamp examination of the eyes, and 24-hour urinary copper measurement. Genetic tests are supplementary for screening but are not routinely available.

A 25-year-old woman presents to the emergency department with a 7-day history of fatigue and nausea. On presentation she denies having abdominal pain, headache, fever, chills, night sweats, vomiting, diarrhea, melena, hematochezia, or weight loss. She recalls changes in the colors of her eyes and darkening urine over the last few days. Her medical history before this is unremarkable. She takes no prescription, over-the-counter, or herbal medications. She works as a librarian and has no occupational toxic exposures. She is single and has one sister with no prior medical history. She denies recent travel, sick contacts, smoking, recreational drug use, or pets at home.

On physical examination, her vital signs are temperature 37.3°C (99.1°F), heart rate 90 beats per minute, blood pressure 125/80 mm Hg, respiration rate 14 per minute, and oxygen saturation 97% on room air. She has icteric sclera and her skin is jaundiced. Cardiac examination is normal. Lungs are clear to auscultation and percussion bilaterally. Her abdomen is soft with no visceromegaly, masses, or tenderness. Extremities are normal with no edema. She is alert and oriented, but she has mild asterixis of the outstretched hands. The neurologic examination is otherwise unremarkable.

The patient’s basic laboratory values are listed in Table 1. Shortly after admission, she develops changes in her mental status, remaining alert but becoming agitated and oriented to person only. In view of her symptoms and laboratory findings, acute liver failure is suspected.

ACUTE LIVER FAILURE

1. The diagnostic criteria for acute liver failure include all of the following except which one?

• Acute elevation of liver biochemical tests
• Presence of preexisting liver disease
• Coagulopathy, defined by an international normalized ratio (INR) of 1.5 or greater
• Encephalopathy
• Duration of symptoms less than 26 weeks

Acute liver failure is defined by acute onset of worsening liver tests, coagulopathy (INR ≥ 1.5), and encephalopathy in patients with no preexisting liver disease and with symptom duration of less than 26 weeks.¹ With a few exceptions, a history of preexisting liver disease negates the diagnosis of acute liver failure. Our patient meets the diagnostic criteria for acute liver failure.

Immediate management

Once acute liver failure is identified or suspected, the next step is to transfer the patient to the intensive care unit for close monitoring of mental status. Serial neurologic evaluations permit early detection of cerebral edema, which is considered the most common cause of death in patients with acute liver failure. Additionally, close monitoring of electrolytes and plasma glucose is necessary since these patients are susceptible to electrolyte disturbances and hypoglycemia.

Patients with acute liver failure are at increased risk of infections and should be routinely screened by obtaining urine and blood cultures.

Gastrointestinal bleeding is not uncommon in patients with acute liver failure and is usually due to gastric stress ulceration. Prophylaxis with a histamine 2 receptor antagonist or proton pump inhibitor should be considered in order to prevent gastrointestinal bleeding.

Treatment with N-acetylcysteine is beneficial, not only in patients with acute liver failure due to acetaminophen overdose, but also in those with acute liver failure from other causes.

CASE CONTINUES:
TRANSFER TO THE INTENSIVE CARE UNIT

The patient, now diagnosed with acute liver failure, is transferred to the intensive care unit. Arterial blood gas measurement shows:

• pH 7.38 (reference range 7.35–7.45)
• Pco₂ 40 mm Hg (36–46)
• Po₂ 97 mm Hg (85–95)
• Hco₃ 22 mmol/L (22–26).

A chest radiograph is obtained and is clear. Computed tomography (CT) of the brain reveals no edema. Transcranial Doppler ultrasonography does not show any intracranial fluid collections.

Blood and urine cultures are negative. Her hemoglobin level remains stable, and she does not develop signs of bleeding. She is started on a proton pump inhibitor for stress ulcer prophylaxis and is empirically given intravenous N-acetylcysteine until the cause of acute liver failure can be determined.

CAUSES OF ACUTE LIVER FAILURE

2. Which of the following can cause acute liver failure?

• Acetaminophen overdose
• Viral hepatitis
• Autoimmune hepatitis
• Wilson disease
• Alcoholic hepatitis

Drug-induced liver injury is the most common cause of acute liver failure in the United States,^2,3 and of all drugs, acetaminophen overdose is the number-one cause. In acetaminophen-induced liver injury, serum aminotransferase levels are usually elevated to more than 1,000 U/L, while serum bilirubin remains normal in the early stages. Antimicrobial agents, antiepileptic drugs, and herbal supplements have also been implicated in acute liver failure. Our patient has denied taking herbal supplements or medications, including over-the-counter ones.

Acute viral hepatitis can explain the patient’s condition. It is a common cause of acute liver failure in the United States.² Hepatitis A and E are more common in developing countries. Other viruses such as cytomegalovirus, Epstein-Barr virus, herpes simplex virus type 1 and 2, and varicella zoster virus can also cause acute liver failure. Serum aminotransferase levels may exceed 1,000 U/L in patients with viral hepatitis.

A young woman presents with acute liver failure: What is the cause? Is her sister at risk?

Autoimmune hepatitis is a rare cause of acute liver failure, but it should be considered in the differential diagnosis, particularly in middle-aged women with autoimmune disorders such as hypothyroidism. Autoimmune hepatitis can cause marked elevation in aminotransferase levels (> 1,000 U/L).

Wilson disease is an autosomal-recessive disease in which there is excessive accumulation of copper in the liver and other organs because of an inherited defect in the biliary excretion of copper. Wilson disease can cause acute liver failure and should be excluded in any patient, particularly if under age 40 with acute onset of unexplained hepatic, neurologic, or psychiatric disease.

Alcoholic hepatitis usually occurs in patients with a long-standing history of heavy alcohol use. As a result, most patients with alcoholic hepatitis have manifestations of chronic liver disease due to alcohol use. Therefore, by definition, it is not a cause of acute liver failure. Additionally, in patients with alcoholic hepatitis, the aspartate aminotransferase (AST) level is elevated but less than 300 IU/mL, and the ratio of AST to alanine aminotransferase (ALT) is usually more than 2.

CASE CONTINUES: FURTHER TESTING

The results of our patient’s serologic tests are shown in Table 2. Other test results:

• Autoimmune markers including antinuclear antibodies, antimitochondrial antibodies, antismooth muscle antibodies, and liver and kidney microsomal antibodies are negative; her immunoglobulin G (IgG) level is normal
• Serum ceruloplasmin 25 mg/dL (normal 21–45)
• Free serum copper 120 µg/dL (normal 8–12)
• Abdominal ultrasonography is unremarkable, with normal liver parenchyma and no intrahepatic or extrahepatic biliary dilatation
• Doppler ultrasonography of the liver shows patent blood vessels.

3. Based on the new data, which of the following statements is correct?

• Hepatitis B is the cause of acute liver failure in this patient
• Herpetic hepatitis cannot be excluded on the basis of the available data
• Wilson disease is most likely the diagnosis, given her elevated free serum copper
• A normal serum ceruloplasmin level is not sufficient to rule out acute liver failure secondary to Wilson disease

Hepatitis B surface antigen and hepatitis B core antibodies were negative in our patient, excluding hepatitis B virus infection. The positive hepatitis B surface antibody indicates prior immunization.

Herpetic hepatitis is an uncommon but important cause of acute liver failure because the mortality rate is high if the patient is not treated early with acyclovir. Fever, elevated aminotransferases, and leukopenia are common with herpetic hepatitis. Fewer than 50% of patients with herpetic hepatitis have vesicular rash.^4,5 The value of antibody serologic testing is limited due to high rates of false-positive and false-negative results. The gold standard diagnostic tests are viral load (detection of viral RNA by polymerase chain reaction), viral staining on liver biopsy, or both. In our patient, herpes simplex virus polymerase chain reaction testing was negative, which makes herpetic hepatitis unlikely.

Wilson disease is a genetic condition in which the ability to excrete copper in the bile is impaired, resulting in accumulation of copper in the hepatocytes. Subsequently, copper is released into the bloodstream and eventually into the urine.

However, copper excretion into the bile is impaired in patients with acute liver failure regardless of the etiology. Therefore, elevated free serum copper and 24-hour urine copper levels are not specific for the diagnosis of acute liver failure secondary to Wilson disease. Moreover, Kayser-Fleischer rings, which represent copper deposition in the limbus of the cornea, may not be apparent in the early stages of Wilson disease.

Wilson disease involves accumulation of copper in the liver and other organs as the result of a genetic defect

Since it is challenging to diagnose Wilson disease in the context of acute liver failure, Korman et al⁶ compared patients with acute liver failure secondary to Wilson disease with patients with acute liver failure secondary to other conditions. They found that alkaline phosphatase levels are frequently decreased in patients with acute liver failure secondary to Wilson disease,⁶ and that a ratio of alkaline phosphatase to total bilirubin of less than 4 is 94% sensitive and 96% specific for the diagnosis.⁶

Hemolysis is common in acute liver failure due to Wilson disease. This leads to disproportionate elevation of AST compared with ALT, since AST is present in red blood cells. Consequently, the ratio of AST to ALT is usually greater than 2.2, which provides a sensitivity of 94% and a specificity of 86% for the diagnosis.⁶ These two ratios together provide 100% sensitivity and 100% specificity for the diagnosis of Wilson disease in the context of acute liver failure.⁶

Ceruloplasmin. Patients with Wilson disease typically have a low ceruloplasmin level. However, because it is an acute-phase reaction protein, ceruloplasmin can be normal or elevated in patients with acute liver failure from Wilson disease.⁶ Therefore, a normal ceruloplasmin level is not sufficient to rule out acute liver failure secondary to Wilson disease.

CASE CONTINUES: A DEFINITIVE DIAGNOSIS

Our patient undergoes further testing, which reveals the following:

• Her 24-hour urinary excretion of copper is 150 µg (reference value < 30)
• Slit-lamp examination is normal and shows no evidence of Kayser-Fleischer rings
• Her ratio of alkaline phosphatase to total bilirubin is 0.77 based on her initial laboratory results (Table 1)
• Her AST-ALT ratio is 3.4.

The diagnosis in our patient is acute liver failure secondary to Wilson disease.

4. What is the most appropriate next step?

• Liver biopsy
• d-penicillamine by mouth
• Trientine by mouth
• Liver transplant
• Plasmapheresis

Liver biopsy. Accumulation of copper in the liver parenchyma in patients with Wilson disease is sporadic. Therefore, qualitative copper staining on liver biopsy can be falsely negative. Quantitative copper measurement in liver tissue is the gold standard for the diagnosis of Wilson disease. However, the test is time-consuming and is not rapidly available in the context of acute liver failure.

Chelating agents such as d-pencillamine and trientine are used to treat the chronic manifestations of Wilson disease but are not useful for acute liver failure secondary to Wilson disease.

Acute liver failure secondary to Wilson disease is life-threatening, and liver transplant is considered the only definitive life-saving therapy.

Therapeutic plasmapheresis has been reported to be a successful adjunctive therapy to bridge patients with acute liver failure secondary to Wilson disease to transplant.⁷ However, liver transplant is still the only definitive treatment.

CASE CONTINUES: THE PATIENT’S SISTER SEEKS CARE

The patient undergoes liver transplantation, with no perioperative or postoperative complications.

The patient’s 18-year-old sister is now seeking medical attention in the outpatient clinic, concerned that she may have Wilson disease. She is otherwise healthy and denies any symptoms or complaints.

5. What is the next step for the patient’s sister?

• Reassurance
• Prophylaxis with trientine
• Check liver enzyme levels, serum ceruloplasmin level, and urine copper, and order a slit-lamp examination
• Genetic testing

Wilson disease can be asymptomatic in its early stages and may be diagnosed incidentally during routine blood tests that reveal abnormal liver enzyme levels. All patients with a confirmed family history of Wilson disease should be screened even if they are asymptomatic. The diagnosis of Wilson disease should be established in first-degree relatives before specific treatment for the relatives is prescribed.

Based on information in Roberts EA, Schilsky ML; American Association for Study of Liver Diseases (AASLD). Diagnosis and treatment of Wilson disease: an update. Hepatology 2008; 7:2089–2111.

The first step in screening a first-degree relative for Wilson disease is to check liver enzyme levels (specifically aminotransferases, alkaline phosphatase, and bilirubin), serum ceruloplasmin level, and 24-hour urine copper, and order an ophthalmologic slit-lamp examination. If any of these tests is abnormal, liver biopsy should be performed for histopathologic evaluation and quantitative copper measurement. Kayser-Fleischer  rings are seen in only 50% of patients with Wilson disease and hepatic involvement, but they are pathognomic. Guidelines⁸ for screening first-degree relatives of Wilson disease patients are shown in Figure 1.

Genetic analysis. ATP7B, the Wilson disease gene, is located on chromosome 13. At least 300 mutations of the gene have been described,² and the most common mutation is present in only 15% to 30% of the Wilson disease population.^8–10 Routine molecular testing of the ATP7B

CASE CONTINUES: WORKUP OF THE PATIENT’S SISTER

The patient’s sister has no symptoms and her physical examination is normal. Slit-lamp examination reveals no evidence of Kayser-Fleischer rings. Her laboratory values, including complete blood counts, complete metabolic panel, and INR, are within normal ranges. Other test results, however, are abnormal:

• Free serum copper level 27 µg/dL (normal 8–12)
• Serum ceruloplasmin 9.0 mg/dL (normal 20–50)
• 24-hour urinary copper excretion 135 µg (normal < 30).

She undergoes liver biopsy for quantitative copper measurement, and the result is very high at 1,118 µg/g dry weight (reference range 10–35). The diagnosis of Wilson disease is established.

TREATING CHRONIC WILSON DISEASE

6. Which of the following is not an appropriate next step for the patient’s sister?

• Tetrathiomolybdate
• d-penicillamine
• Trientine
• Zinc salts
• Prednisone

The goal of medical treatment of chronic Wilson disease is to improve symptoms and prevent progression of the disease.

Chelating agents and zinc salts are the most commonly used medicines in the management of Wilson disease. Chelating agents remove copper from tissue, whereas zinc blocks the intestinal absorption of copper and stimulates the synthesis of endogenous chelators such as metallothioneins. Tetrathiomolybdate is an alternative agent developed to interfere with the distribution of excess body copper to susceptible target sites by reducing free serum copper (Table 3). There are no data to support the use of prednisone in the treatment of Wilson disease.

During treatment with chelating agents, 24-hour urinary excretion of copper is routinely monitored to determine the efficacy of therapy and adherence to treatment. Once de-coppering is achieved, as evidenced by a normalization of 24-hour urine copper excretion, the chelating agent can be switched to zinc salts to prevent intestinal absorption of copper.

Clinical and biochemical stabilization is achieved typically within 2 to 6 months of the initial treatment with chelating agents.⁸ Organ meats, nuts, shellfish, and chocolate are rich in copper and should be avoided.

The patient’s sister is started on trientine 250 mg orally three times daily on an empty stomach at least 1 hour before meals. Treatment is monitored by following 24-hour urine copper measurement. A 24-hour urine copper measurement at 3 months after starting treatment has increased from 54 at baseline to 350 µg, which indicates that the copper is being removed from tissues. The plan is for early substitution of zinc for long-term maintenance once de-coppering is completed.

KEY POINTS

• Acute liver failure is severe acute liver injury characterized by coagulopathy (INR ≥ 1.5) and encephalopathy in a patient with no preexisting liver disease and with duration of symptoms less than 26 weeks.
• Acute liver failure secondary to Wilson disease is uncommon but should be excluded, particularly in young patients.
• The diagnosis of Wilson disease in the setting of acute liver failure is challenging because the serum ceruloplasmin level may be normal in acute liver failure secondary to Wilson disease, and free serum copper and 24-hour urine copper are usually elevated in all acute liver failure patients regardless of the etiology.
• A ratio of alkaline phosphatase to total bilirubin of less than 4 plus an AST-ALT ratio greater than 2.2 in a patient with acute liver failure should be regarded as Wilson disease until proven otherwise (Figure 2).
• Acute liver failure secondary to Wilson disease is usually fatal, and emergency liver transplant is a life-saving procedure.
• Screening of first-degree relatives of Wilson disease patients should include a history and physical examination, liver enzyme tests, complete blood cell count, serum ceruloplasmin level, serum free copper level, slit-lamp examination of the eyes, and 24-hour urinary copper measurement. Genetic tests are supplementary for screening but are not routinely available.

A 25-year-old woman presents to the emergency department with a 7-day history of fatigue and nausea. On presentation she denies having abdominal pain, headache, fever, chills, night sweats, vomiting, diarrhea, melena, hematochezia, or weight loss. She recalls changes in the colors of her eyes and darkening urine over the last few days. Her medical history before this is unremarkable. She takes no prescription, over-the-counter, or herbal medications. She works as a librarian and has no occupational toxic exposures. She is single and has one sister with no prior medical history. She denies recent travel, sick contacts, smoking, recreational drug use, or pets at home.

On physical examination, her vital signs are temperature 37.3°C (99.1°F), heart rate 90 beats per minute, blood pressure 125/80 mm Hg, respiration rate 14 per minute, and oxygen saturation 97% on room air. She has icteric sclera and her skin is jaundiced. Cardiac examination is normal. Lungs are clear to auscultation and percussion bilaterally. Her abdomen is soft with no visceromegaly, masses, or tenderness. Extremities are normal with no edema. She is alert and oriented, but she has mild asterixis of the outstretched hands. The neurologic examination is otherwise unremarkable.

The patient’s basic laboratory values are listed in Table 1. Shortly after admission, she develops changes in her mental status, remaining alert but becoming agitated and oriented to person only. In view of her symptoms and laboratory findings, acute liver failure is suspected.

ACUTE LIVER FAILURE

1. The diagnostic criteria for acute liver failure include all of the following except which one?

• Acute elevation of liver biochemical tests
• Presence of preexisting liver disease
• Coagulopathy, defined by an international normalized ratio (INR) of 1.5 or greater
• Encephalopathy
• Duration of symptoms less than 26 weeks

Acute liver failure is defined by acute onset of worsening liver tests, coagulopathy (INR ≥ 1.5), and encephalopathy in patients with no preexisting liver disease and with symptom duration of less than 26 weeks.¹ With a few exceptions, a history of preexisting liver disease negates the diagnosis of acute liver failure. Our patient meets the diagnostic criteria for acute liver failure.

Immediate management

Once acute liver failure is identified or suspected, the next step is to transfer the patient to the intensive care unit for close monitoring of mental status. Serial neurologic evaluations permit early detection of cerebral edema, which is considered the most common cause of death in patients with acute liver failure. Additionally, close monitoring of electrolytes and plasma glucose is necessary since these patients are susceptible to electrolyte disturbances and hypoglycemia.

Patients with acute liver failure are at increased risk of infections and should be routinely screened by obtaining urine and blood cultures.

Gastrointestinal bleeding is not uncommon in patients with acute liver failure and is usually due to gastric stress ulceration. Prophylaxis with a histamine 2 receptor antagonist or proton pump inhibitor should be considered in order to prevent gastrointestinal bleeding.

Treatment with N-acetylcysteine is beneficial, not only in patients with acute liver failure due to acetaminophen overdose, but also in those with acute liver failure from other causes.

CASE CONTINUES:
TRANSFER TO THE INTENSIVE CARE UNIT

The patient, now diagnosed with acute liver failure, is transferred to the intensive care unit. Arterial blood gas measurement shows:

• pH 7.38 (reference range 7.35–7.45)
• Pco₂ 40 mm Hg (36–46)
• Po₂ 97 mm Hg (85–95)
• Hco₃ 22 mmol/L (22–26).

A chest radiograph is obtained and is clear. Computed tomography (CT) of the brain reveals no edema. Transcranial Doppler ultrasonography does not show any intracranial fluid collections.

Blood and urine cultures are negative. Her hemoglobin level remains stable, and she does not develop signs of bleeding. She is started on a proton pump inhibitor for stress ulcer prophylaxis and is empirically given intravenous N-acetylcysteine until the cause of acute liver failure can be determined.

CAUSES OF ACUTE LIVER FAILURE

2. Which of the following can cause acute liver failure?

• Acetaminophen overdose
• Viral hepatitis
• Autoimmune hepatitis
• Wilson disease
• Alcoholic hepatitis

Drug-induced liver injury is the most common cause of acute liver failure in the United States,^2,3 and of all drugs, acetaminophen overdose is the number-one cause. In acetaminophen-induced liver injury, serum aminotransferase levels are usually elevated to more than 1,000 U/L, while serum bilirubin remains normal in the early stages. Antimicrobial agents, antiepileptic drugs, and herbal supplements have also been implicated in acute liver failure. Our patient has denied taking herbal supplements or medications, including over-the-counter ones.

Acute viral hepatitis can explain the patient’s condition. It is a common cause of acute liver failure in the United States.² Hepatitis A and E are more common in developing countries. Other viruses such as cytomegalovirus, Epstein-Barr virus, herpes simplex virus type 1 and 2, and varicella zoster virus can also cause acute liver failure. Serum aminotransferase levels may exceed 1,000 U/L in patients with viral hepatitis.

A young woman presents with acute liver failure: What is the cause? Is her sister at risk?

Autoimmune hepatitis is a rare cause of acute liver failure, but it should be considered in the differential diagnosis, particularly in middle-aged women with autoimmune disorders such as hypothyroidism. Autoimmune hepatitis can cause marked elevation in aminotransferase levels (> 1,000 U/L).

Wilson disease is an autosomal-recessive disease in which there is excessive accumulation of copper in the liver and other organs because of an inherited defect in the biliary excretion of copper. Wilson disease can cause acute liver failure and should be excluded in any patient, particularly if under age 40 with acute onset of unexplained hepatic, neurologic, or psychiatric disease.

Alcoholic hepatitis usually occurs in patients with a long-standing history of heavy alcohol use. As a result, most patients with alcoholic hepatitis have manifestations of chronic liver disease due to alcohol use. Therefore, by definition, it is not a cause of acute liver failure. Additionally, in patients with alcoholic hepatitis, the aspartate aminotransferase (AST) level is elevated but less than 300 IU/mL, and the ratio of AST to alanine aminotransferase (ALT) is usually more than 2.

CASE CONTINUES: FURTHER TESTING

The results of our patient’s serologic tests are shown in Table 2. Other test results:

• Autoimmune markers including antinuclear antibodies, antimitochondrial antibodies, antismooth muscle antibodies, and liver and kidney microsomal antibodies are negative; her immunoglobulin G (IgG) level is normal
• Serum ceruloplasmin 25 mg/dL (normal 21–45)
• Free serum copper 120 µg/dL (normal 8–12)
• Abdominal ultrasonography is unremarkable, with normal liver parenchyma and no intrahepatic or extrahepatic biliary dilatation
• Doppler ultrasonography of the liver shows patent blood vessels.

3. Based on the new data, which of the following statements is correct?

• Hepatitis B is the cause of acute liver failure in this patient
• Herpetic hepatitis cannot be excluded on the basis of the available data
• Wilson disease is most likely the diagnosis, given her elevated free serum copper
• A normal serum ceruloplasmin level is not sufficient to rule out acute liver failure secondary to Wilson disease

Hepatitis B surface antigen and hepatitis B core antibodies were negative in our patient, excluding hepatitis B virus infection. The positive hepatitis B surface antibody indicates prior immunization.

Herpetic hepatitis is an uncommon but important cause of acute liver failure because the mortality rate is high if the patient is not treated early with acyclovir. Fever, elevated aminotransferases, and leukopenia are common with herpetic hepatitis. Fewer than 50% of patients with herpetic hepatitis have vesicular rash.^4,5 The value of antibody serologic testing is limited due to high rates of false-positive and false-negative results. The gold standard diagnostic tests are viral load (detection of viral RNA by polymerase chain reaction), viral staining on liver biopsy, or both. In our patient, herpes simplex virus polymerase chain reaction testing was negative, which makes herpetic hepatitis unlikely.

Wilson disease is a genetic condition in which the ability to excrete copper in the bile is impaired, resulting in accumulation of copper in the hepatocytes. Subsequently, copper is released into the bloodstream and eventually into the urine.

However, copper excretion into the bile is impaired in patients with acute liver failure regardless of the etiology. Therefore, elevated free serum copper and 24-hour urine copper levels are not specific for the diagnosis of acute liver failure secondary to Wilson disease. Moreover, Kayser-Fleischer rings, which represent copper deposition in the limbus of the cornea, may not be apparent in the early stages of Wilson disease.

Wilson disease involves accumulation of copper in the liver and other organs as the result of a genetic defect

Since it is challenging to diagnose Wilson disease in the context of acute liver failure, Korman et al⁶ compared patients with acute liver failure secondary to Wilson disease with patients with acute liver failure secondary to other conditions. They found that alkaline phosphatase levels are frequently decreased in patients with acute liver failure secondary to Wilson disease,⁶ and that a ratio of alkaline phosphatase to total bilirubin of less than 4 is 94% sensitive and 96% specific for the diagnosis.⁶

Hemolysis is common in acute liver failure due to Wilson disease. This leads to disproportionate elevation of AST compared with ALT, since AST is present in red blood cells. Consequently, the ratio of AST to ALT is usually greater than 2.2, which provides a sensitivity of 94% and a specificity of 86% for the diagnosis.⁶ These two ratios together provide 100% sensitivity and 100% specificity for the diagnosis of Wilson disease in the context of acute liver failure.⁶

Ceruloplasmin. Patients with Wilson disease typically have a low ceruloplasmin level. However, because it is an acute-phase reaction protein, ceruloplasmin can be normal or elevated in patients with acute liver failure from Wilson disease.⁶ Therefore, a normal ceruloplasmin level is not sufficient to rule out acute liver failure secondary to Wilson disease.

CASE CONTINUES: A DEFINITIVE DIAGNOSIS

Our patient undergoes further testing, which reveals the following:

• Her 24-hour urinary excretion of copper is 150 µg (reference value < 30)
• Slit-lamp examination is normal and shows no evidence of Kayser-Fleischer rings
• Her ratio of alkaline phosphatase to total bilirubin is 0.77 based on her initial laboratory results (Table 1)
• Her AST-ALT ratio is 3.4.

The diagnosis in our patient is acute liver failure secondary to Wilson disease.

4. What is the most appropriate next step?

• Liver biopsy
• d-penicillamine by mouth
• Trientine by mouth
• Liver transplant
• Plasmapheresis

Liver biopsy. Accumulation of copper in the liver parenchyma in patients with Wilson disease is sporadic. Therefore, qualitative copper staining on liver biopsy can be falsely negative. Quantitative copper measurement in liver tissue is the gold standard for the diagnosis of Wilson disease. However, the test is time-consuming and is not rapidly available in the context of acute liver failure.

Chelating agents such as d-pencillamine and trientine are used to treat the chronic manifestations of Wilson disease but are not useful for acute liver failure secondary to Wilson disease.

Acute liver failure secondary to Wilson disease is life-threatening, and liver transplant is considered the only definitive life-saving therapy.

Therapeutic plasmapheresis has been reported to be a successful adjunctive therapy to bridge patients with acute liver failure secondary to Wilson disease to transplant.⁷ However, liver transplant is still the only definitive treatment.

CASE CONTINUES: THE PATIENT’S SISTER SEEKS CARE

The patient undergoes liver transplantation, with no perioperative or postoperative complications.

The patient’s 18-year-old sister is now seeking medical attention in the outpatient clinic, concerned that she may have Wilson disease. She is otherwise healthy and denies any symptoms or complaints.

5. What is the next step for the patient’s sister?

• Reassurance
• Prophylaxis with trientine
• Check liver enzyme levels, serum ceruloplasmin level, and urine copper, and order a slit-lamp examination
• Genetic testing

Wilson disease can be asymptomatic in its early stages and may be diagnosed incidentally during routine blood tests that reveal abnormal liver enzyme levels. All patients with a confirmed family history of Wilson disease should be screened even if they are asymptomatic. The diagnosis of Wilson disease should be established in first-degree relatives before specific treatment for the relatives is prescribed.

Based on information in Roberts EA, Schilsky ML; American Association for Study of Liver Diseases (AASLD). Diagnosis and treatment of Wilson disease: an update. Hepatology 2008; 7:2089–2111.

The first step in screening a first-degree relative for Wilson disease is to check liver enzyme levels (specifically aminotransferases, alkaline phosphatase, and bilirubin), serum ceruloplasmin level, and 24-hour urine copper, and order an ophthalmologic slit-lamp examination. If any of these tests is abnormal, liver biopsy should be performed for histopathologic evaluation and quantitative copper measurement. Kayser-Fleischer  rings are seen in only 50% of patients with Wilson disease and hepatic involvement, but they are pathognomic. Guidelines⁸ for screening first-degree relatives of Wilson disease patients are shown in Figure 1.

Genetic analysis. ATP7B, the Wilson disease gene, is located on chromosome 13. At least 300 mutations of the gene have been described,² and the most common mutation is present in only 15% to 30% of the Wilson disease population.^8–10 Routine molecular testing of the ATP7B

CASE CONTINUES: WORKUP OF THE PATIENT’S SISTER

The patient’s sister has no symptoms and her physical examination is normal. Slit-lamp examination reveals no evidence of Kayser-Fleischer rings. Her laboratory values, including complete blood counts, complete metabolic panel, and INR, are within normal ranges. Other test results, however, are abnormal:

• Free serum copper level 27 µg/dL (normal 8–12)
• Serum ceruloplasmin 9.0 mg/dL (normal 20–50)
• 24-hour urinary copper excretion 135 µg (normal < 30).

She undergoes liver biopsy for quantitative copper measurement, and the result is very high at 1,118 µg/g dry weight (reference range 10–35). The diagnosis of Wilson disease is established.

TREATING CHRONIC WILSON DISEASE

6. Which of the following is not an appropriate next step for the patient’s sister?

• Tetrathiomolybdate
• d-penicillamine
• Trientine
• Zinc salts
• Prednisone

The goal of medical treatment of chronic Wilson disease is to improve symptoms and prevent progression of the disease.

Chelating agents and zinc salts are the most commonly used medicines in the management of Wilson disease. Chelating agents remove copper from tissue, whereas zinc blocks the intestinal absorption of copper and stimulates the synthesis of endogenous chelators such as metallothioneins. Tetrathiomolybdate is an alternative agent developed to interfere with the distribution of excess body copper to susceptible target sites by reducing free serum copper (Table 3). There are no data to support the use of prednisone in the treatment of Wilson disease.

During treatment with chelating agents, 24-hour urinary excretion of copper is routinely monitored to determine the efficacy of therapy and adherence to treatment. Once de-coppering is achieved, as evidenced by a normalization of 24-hour urine copper excretion, the chelating agent can be switched to zinc salts to prevent intestinal absorption of copper.

Clinical and biochemical stabilization is achieved typically within 2 to 6 months of the initial treatment with chelating agents.⁸ Organ meats, nuts, shellfish, and chocolate are rich in copper and should be avoided.

The patient’s sister is started on trientine 250 mg orally three times daily on an empty stomach at least 1 hour before meals. Treatment is monitored by following 24-hour urine copper measurement. A 24-hour urine copper measurement at 3 months after starting treatment has increased from 54 at baseline to 350 µg, which indicates that the copper is being removed from tissues. The plan is for early substitution of zinc for long-term maintenance once de-coppering is completed.

KEY POINTS

• Acute liver failure is severe acute liver injury characterized by coagulopathy (INR ≥ 1.5) and encephalopathy in a patient with no preexisting liver disease and with duration of symptoms less than 26 weeks.
• Acute liver failure secondary to Wilson disease is uncommon but should be excluded, particularly in young patients.
• The diagnosis of Wilson disease in the setting of acute liver failure is challenging because the serum ceruloplasmin level may be normal in acute liver failure secondary to Wilson disease, and free serum copper and 24-hour urine copper are usually elevated in all acute liver failure patients regardless of the etiology.
• A ratio of alkaline phosphatase to total bilirubin of less than 4 plus an AST-ALT ratio greater than 2.2 in a patient with acute liver failure should be regarded as Wilson disease until proven otherwise (Figure 2).
• Acute liver failure secondary to Wilson disease is usually fatal, and emergency liver transplant is a life-saving procedure.
• Screening of first-degree relatives of Wilson disease patients should include a history and physical examination, liver enzyme tests, complete blood cell count, serum ceruloplasmin level, serum free copper level, slit-lamp examination of the eyes, and 24-hour urinary copper measurement. Genetic tests are supplementary for screening but are not routinely available.

What a difference a single nucleotide can make! The human genome contains more than 3 billion base pairs. Yet having a different nucleotide in only one pair can make a big difference in how we respond to a disease or its treatment.

Specifically, in hepatitis C virus infection, people born with the nucleotide cytosine (C) at location rs12979860 in both alleles of the gene that codes for interleukin 28B (the IL28B CC genotype) can count themselves luckier than those born with thymine (T) in this location in one of their alleles (the CT genotype) or both of their alleles (the TT genotype). Those with the CC genotype are more likely to clear the virus spontaneously, and even if the infection persists, it is less likely to progress to liver cancer and more likely to respond to treatment with interferon.

Here, we review the IL28B polymorphism and its implications in treating hepatitis C.

GENETIC POLYMORPHISM AND HUMAN DISEASE

Of the 3 billion base pairs of nucleotides, fewer than 1% differ between individuals, but this 1% is responsible for the diversity of human beings. Differences in genetic sequences among individuals are called genetic polymorphisms. A single-nucleotide polymorphism is a DNA sequence variation that occurs in a single nucleotide in the genome. For example, two sequenced DNA fragments from different individuals, AAGCCTA and AAGCTTA, contain a difference in a single nucleotide.

Genetic variations such as these underlie some of the differences in our susceptibility to disease, the severity of illness we develop, and our response to treatments. Therefore, identifying genetic polymorphisms may shed light on biologic pathways involved in diseases and may uncover new targets for therapy.¹

Genome-wide association studies have looked at hundreds of thousands of single-nucleotide polymorphisms to try to identify most of the common genetic differences among people and relate them to common chronic diseases such as coronary artery disease,² type 2 diabetes,³ stroke,⁴ breast cancer,⁵ rheumatoid arthritis,⁶ Alzheimer disease,⁷ and, more recently, hepatitis C virus infection.⁸

HEPATITIS C VIRUS: A MAJOR CAUSE OF LIVER DISEASE

Hepatitis C virus infection is a major cause of chronic liver disease and hepatocellular carcinoma and has become the most common indication for liver transplantation in the United States.⁹

This virus has six distinct genotypes throughout the world, with multiple subtypes in each genotype. (A genotype is a classification of a virus based on its RNA.⁹) In this review, we will focus on genotype 1; hence, “hepatitis C virus” will refer to hepatitis C virus genotype 1.

Our knowledge of the biology, pathogenesis, and treatment of hepatitis C has been advancing. Originally, fewer than 50% of patients responded to therapy with the combination of pegylated interferon and ribavirin,^10,11 but since 2011 the response rate has increased to approximately 70% with the approval of the protease inhibitors telaprevir and boceprevir, used in combination with pegylated interferon and ribavirin.^12–15

Unfortunately, interferon-based treatment is often complicated by side effects such as fatigue, influenza-like symptoms, hematologic abnormalities, and neuropsychiatric symptoms. An accurate way to predict response would help patients make informed decisions about antiviral treatment, taking into account the risk and possible benefit for individual patients.

GENETIC POLYMORPHISM AND HEPATITIS C VIRUS INFECTION

Genome-wide association studies have identified single-nucleotide polymorphisms in the IL28B gene that are associated with differences in response to hepatitis C treatment.⁸

Studying 565,759 polymorphisms in 1,137 patients, researchers at Duke University identified a single-nucleotide polymorphism at location rs12979860 in IL28B (Figure 1) that was strongly associated with response to combination therapy with pegylated interferon and ribavirin.⁸ The chance of cure with this standard treatment is twice as high in patients who are homozygous for cytosine in this location (the CC genotype) than in those who are heterozygous (CT) or homozygous for thymine in this location (the TT genotype) (Table 1).

Adding one of the new protease inhibitors, telaprevir or boceprevir, to the standard hepatitis C treatment substantially improves the cure rates in all three IL28B genotypes, but especially in people with CT or TT, in whom the response rate almost triples with the addition of one of these drugs. Those with the CC genotype (who are more likely to be cured with pegylated interferon and ribavirin alone) also achieve an increase (although minimal) in cure rates when a protease inhibitor is included in the regimen (TABLE 1).^13–15 Thus, it remains unclear if adding a protease inhibitor to pegylated interferon plus ribavirin in patients with the IL28B CC genotype translates into added effectiveness worth the additional cost of the protease inhibitor in previously untreated patients.

Additionally, the effect of the IL28B genotype on telaprevir-based triple therapy has been disputed in more recent studies. In a subgroup analysis of the results of a trial that evaluated telaprevir in the treatment of hepatitis C, researchers found that sustained virologic response rates were significantly higher in the telaprevir group, and this was similar across the different IL28B polymorphisms.¹⁶

The favorable IL28B CC genotype is associated with higher rates of rapid virologic response to antiviral therapy.^13–15 Of note, almost all patients who achieve a rapid virologic response do well, with a high rate of sustained virologic response even after a shorter duration of therapy (24 vs 48 weeks). Therefore, in addition to predicting response to interferon before starting treatment, the IL28B CC genotype may also identify patients who need only a shorter duration of therapy.

Interestingly, the C allele is much more frequent in white than in African American populations, an important observation that explains the racial difference in response to hepatitis C therapy.⁸

Two other research groups, from Asia and Australia, performed independent genome-wide association studies that identified different single-nucleotide polymorphisms (eg, rs8099917) in the same IL28B gene as predictors of response to treatment in patients with hepatitis C virus infection.^17,18 These findings may be explained by linkage disequilibrium, which means that these single-nucleotide polymorphisms are found more frequently together in the same patient due to their proximity to each other. In this review, we will focus on the rs12979860 polymorphism; hence “IL28B genotype” will refer to the single-nucleotide polymorphism at rs12979860, unless otherwise specified.

The favorable CC genotype is less common in African Americans than in patients of other ethnicities.¹⁹ Moreover, although IL28B CC is associated with a better response rate to interferon-based antiviral therapy across all ethnicities, those of African American descent with the CC genotype are less likely to achieve a sustained virologic response than white or Hispanic Americans.⁸

BIOLOGIC ASSOCIATION: IL28B POLYMORPHISM AND HEPATITIS C

The interferon lambda family consists of three cytokines:

• Interleukin 29 (interferon lambda 1)
• Interleukin 28A (interferon lambda 2)
• Interleukin 28B (interferon  lambda 3).

Production of these three molecules can be triggered by viral infection, and they induce antiviral activity through both innate and adaptive immune pathways. They signal through the IL10R-IL28R receptor complex.^20–22 This receptor activates the JAK-STAT (Janus kinase-signal transducer and activator of transcription) pathway, which regulates a large number of interferon-stimulated genes, primarily through the interferon-stimulated response element (Figure 2).

A 2013 study found that interferon-stimulated gene expression levels in patients with normal livers were highest in those with the CC genotype, intermediate with CT, and lowest with TT. Interestingly, this pattern was reversed in those with hepatitis C virus infection, indicating a relationship between the IL28B genotype and gene expression before infection.23

The mechanism underlying the association between the IL28B polymorphism and response to hepatitis C treatment is not well understood. The unfavorable TT genotype seems to lead to continuous activation of a subset of interferon-stimulated genes in the presence of intracellular hepatitis C viral RNA. But this level of expression is not sufficient to eliminate the virus from the cells. Instead, it might lead to up-regulation of interferon-inhibitory molecules that suppress JAK-STAT signaling, thereby reducing sensitivity to interferon signaling. Therefore, the hepatocyte not only cannot clear the virus by itself, but also cannot induce strong interferon-stimulated gene expression when interferon is given during therapy.^20–22

The recently identified ss469425590 polymorphism, which is located in close proximity to rs12979860 in the IL28B gene, is particularly interesting, as it suggests a possible molecular mechanism. The delta G frameshift variant creates a novel gene called IFNL4, which is transiently activated in response to hepatitis C virus infection.²⁴IFNL4 stimulates STAT1 and STAT2 phosphorylation and induces the expression of interferon-stimulated genes. Increased interferon-stimulated gene expression has been shown to be associated with decreased response to pegylated interferon-ribavirin treatment. These observations suggest that the ss469425590 delta G allele is responsible for the increased activation of interferon-stimulated genes and the lower sustained virologic response rate observed in patients who receive pegylated interferon-ribavirin treatment. It is possible that the activation of interferon-stimulated genes in patients with the ss469425590 delta G/delta G genotype reduces interferon-stimulated gene responsiveness to interferon alpha, which normally activates interferon-stimulated genes and inhibits hepatitis C progression.²⁴

IL28B POLYMORPHISM AND ACUTE HEPATITIS C VIRUS INFECTION

From 70% to 80% of acute hepatitis C virus infections persist and become chronic, while 20% to 30% spontaneously resolve. Epidemiologic, viral, and host factors have been associated with the differences in viral clearance or persistence, and studies have found that a strong host immune response against the virus favors viral clearance. Thus, variation in the genes involved in the immune response may contribute to one’s ability to clear the virus. Consistent with these observations, recent studies have shown that the polymorphism in the IL28 gene region encoding interferon lambda 3 strongly predicts spontaneous resolution of acute hepatitis C virus infection. People who have the IL28B CC genotype are three times more likely to spontaneously clear the virus than those with the CT or TT genotype (Figure 3).²⁴

IL28B POLYMORPHISM AND THE NATURAL HISTORY OF HEPATITIS C

In people in whom hepatitis C virus infection persists, up to 20% develop progressive liver fibrosis and eventually cirrhosis over 10 to 20 years.^19,25,26 The speed at which fibrosis develops in these patients is variable and unpredictable.²⁵ The relationship between IL28B polymorphisms and hepatic fibrosis in patients with chronic hepatitis C virus infection has not been clearly established, although a study indicated that in patients with a known date of infection, the IL28B genotype is not associated with progression of hepatic fibrosis.²⁷ Obstacles in this field of study are that it is difficult to determine accurately when the patient contracted the virus, and that serial liver biopsies are needed to investigate the progression of hepatic fibrosis.

Patients with chronic hepatitis C virus infection are also at higher risk of hepatocellular carcinoma compared with the general population.²⁸ An analysis of explanted livers of patients with hepatitis C found that the prevalence of hepatocellular carcinoma in those with the unfavorable TT genotype was significantly higher than with the other genotypes.²⁹ Similarly, an earlier study demonstrated that patients with hepatitis C-associated hepatocellular carcinoma carried the T allele more frequently.³⁰ As with other aspects of IL28B associations with hepatitis C, these findings indicate that the C allele confers a certain degree of protection.

An important implication of these relationships is that they may eventually help identify patients at greater risk, who therefore need earlier intervention.

IL28B POLYMORPHISM AND LIVER TRANSPLANTATION

Hepatitis C virus infection always recurs after liver transplantation, with serious consequences that include cirrhosis and liver failure. Recurrent hepatitis C virus infection has become an important reason for repeat transplantation in the United States.

Results of treatment with pegylated interferon and ribavirin for recurrent hepatitis C after liver transplantation have been disappointing, with response rates lower than 30% and significant side effects.³¹ Identifying the factors that predict the response to therapy allows for better selection of treatment candidates.

Similar to the way the IL28B genotype predicts response to antiviral therapy in the nontransplant setting, the IL28B genotypes of both the recipient and the donor are strongly and independently associated with response to interferon-based treatment in patients with hepatitis C after liver transplantation. The IL28B CC genotype in either the recipient or the donor is associated with a higher rate of response to pegylated interferon and ribavirin combination therapy after liver transplantation.^30,32 For example, the response rate to therapy after liver transplantation reaches 86% in CC-donor and CC-recipient livers, compared with 0% in TT-donor and TT-recipient livers.

Additionally, the IL28B genotype of the recipient may determine the severity of histologic recurrence of hepatitis C, as indicated by progressive hepatic fibrosis. A recipient IL28B TT genotype is associated with more severe histologic recurrence of hepatitis C.³³

These data suggest that CC donor livers might be preferentially allocated to patients with hepatitis C virus infection.

IL28B AND OTHER FACTORS IN HEPATITIS C VIRUS INFECTION

Although it is tempting to think that the IL28B polymorphism is the sole predictor of response to antiviral therapy, it is but one of several known factors in the virus and the host.

While IL28B polymorphisms are the most important predictor of sustained virologic response with an interferon-based regimen, a rapid virologic response (undetectable viral load at 4 weeks) had superior predictive value and specificity in one study.³⁴ In fact, for patients with chronic hepatitis C infection who achieved a rapid virologic response with pegylated interferon and ribavirin, the IL28B polymorphism had no effect on the rate of sustained virologic response. However, it did predict a sustained virologic response in the group who did not achieve rapid virologic response.

In a study of patients with acute hepatitis C infection,³⁵ jaundice and the IL28 rs12979860 CC genotype both predicted spontaneous clearance. The best predictor of viral persistence was the combination of the CT or TT genotype plus the absence of jaundice, which had a predictive value of 98%.

IL28B AND THE FUTURE OF HEPATITIS C VIRUS THERAPY

New oral agents were recently approved for treating hepatitis C. As of November 2014, these included simeprevir, sofosbuvir, and ledipasvir.

Simeprevir is a second-generation NS3/4A protease inhibitor approved for use in combination with pegylated interferon and ribavirin. A recent phase 3 trial evaluating simeprevir in patients who had relapsed after prior therapy found sustained virologic response rates to be higher with simeprevir than with placebo, irrespective of IL28B status.³⁶ This finding was similar to that of a trial of telaprevir.¹⁶

Sofosbuvir is a nucleotide analogue NS5B polymerase inhibitor that becomes incorporated into the growing RNA, inducing a chain termination event.³⁷ In phase 3 trials,^38,39 researchers found an initial rapid decrease in viral load for patients treated with this agent regardless of IL28B status.

In the NEUTRINO trial (Sofosbuvir With Peginterferon Alfa 2a and Ribavirin for 12 Weeks in Treatment-Naive Subjects With Chronic Genotype 1, 4, 5, or 6 HCV Infection),³⁸ which used sofusbuvir in combination with interferon and ribavirin, the rate of sustained virologic response was higher in those with the favorable CC genotype (98%) than with a non-CC genotype (87%).

In COSMOS (A Study of TMC435 in Combination With PSI-7977 [GS7977] in Chronic Hepatitis C Genotype 1-Infected Prior Null Responders to Peginterferon/Ribavirin Therapy or HCV Treatment-Naive Patients),³⁹ which used a combination of simeprevir, sofosbuvir, and ribavirin, the rate of sustained virologic response was higher in those with the CC genotype (100%) than with the TT genotype (83%; Table 1).

These new medications have radically changed the landscape of hepatitis C therapy and have also unlocked the potential for developing completely interferon-free regimens.

Other new interferon-free regimens such as ledipasvir, daclatasvir, and asunaprevir promise high rates of sustained virologic response, which makes the utility of testing for IL28B polymorphisms to predict sustained virologic response very much diminished (Table 1).^40,41 However, these new drugs are expected to be expensive, and IL28B polymorphisms may be used to identify candidates who are more likely to respond to pegylated interferon and ribavirin, particularly in resource-poor settings and in developing countries. Additionally, patients who have contraindications to these newer therapies will still likely need an interferon-based regimen, and thus the IL28B polymorphism will still be important in predicting treatment response and prognosis.

IL28B WILL STILL BE RELEVANT IN THE INTERFERON-FREE AGE

The IL28B polymorphism is a strong predictor of spontaneous clearance of hepatitis C virus and responsiveness to interferon-based therapy, and testing for it has demonstrated a great potential to improve patient care. IL28B testing has become available for clinical use and may optimize the outcome of hepatitis C treatment by helping us to select the best treatment for individual patients and minimizing the duration of therapy and the side effects associated with interferon-based antiviral medications.

As newer therapies have shifted toward interferon-free regimens that offer very high sustained virologic response rates, the usefulness of  IL28B polymorphism as a clinical test to predict the response rate to antiviral therapy is minimized substantially. It may remain clinically relevant in resource-poor settings and in developing countries, especially in light of the potentially prohibitive costs of the newer regimens, and for patients in whom these treatments are contraindicated. This does not minimize the lesson we learned from the discovery of the IL28B gene and the impact on our understanding of the pathogenesis of hepatitis C virus infection.

What a difference a single nucleotide can make! The human genome contains more than 3 billion base pairs. Yet having a different nucleotide in only one pair can make a big difference in how we respond to a disease or its treatment.

Specifically, in hepatitis C virus infection, people born with the nucleotide cytosine (C) at location rs12979860 in both alleles of the gene that codes for interleukin 28B (the IL28B CC genotype) can count themselves luckier than those born with thymine (T) in this location in one of their alleles (the CT genotype) or both of their alleles (the TT genotype). Those with the CC genotype are more likely to clear the virus spontaneously, and even if the infection persists, it is less likely to progress to liver cancer and more likely to respond to treatment with interferon.

Here, we review the IL28B polymorphism and its implications in treating hepatitis C.

GENETIC POLYMORPHISM AND HUMAN DISEASE

Of the 3 billion base pairs of nucleotides, fewer than 1% differ between individuals, but this 1% is responsible for the diversity of human beings. Differences in genetic sequences among individuals are called genetic polymorphisms. A single-nucleotide polymorphism is a DNA sequence variation that occurs in a single nucleotide in the genome. For example, two sequenced DNA fragments from different individuals, AAGCCTA and AAGCTTA, contain a difference in a single nucleotide.

Genetic variations such as these underlie some of the differences in our susceptibility to disease, the severity of illness we develop, and our response to treatments. Therefore, identifying genetic polymorphisms may shed light on biologic pathways involved in diseases and may uncover new targets for therapy.¹

Genome-wide association studies have looked at hundreds of thousands of single-nucleotide polymorphisms to try to identify most of the common genetic differences among people and relate them to common chronic diseases such as coronary artery disease,² type 2 diabetes,³ stroke,⁴ breast cancer,⁵ rheumatoid arthritis,⁶ Alzheimer disease,⁷ and, more recently, hepatitis C virus infection.⁸

HEPATITIS C VIRUS: A MAJOR CAUSE OF LIVER DISEASE

Hepatitis C virus infection is a major cause of chronic liver disease and hepatocellular carcinoma and has become the most common indication for liver transplantation in the United States.⁹

This virus has six distinct genotypes throughout the world, with multiple subtypes in each genotype. (A genotype is a classification of a virus based on its RNA.⁹) In this review, we will focus on genotype 1; hence, “hepatitis C virus” will refer to hepatitis C virus genotype 1.

Our knowledge of the biology, pathogenesis, and treatment of hepatitis C has been advancing. Originally, fewer than 50% of patients responded to therapy with the combination of pegylated interferon and ribavirin,^10,11 but since 2011 the response rate has increased to approximately 70% with the approval of the protease inhibitors telaprevir and boceprevir, used in combination with pegylated interferon and ribavirin.^12–15

Unfortunately, interferon-based treatment is often complicated by side effects such as fatigue, influenza-like symptoms, hematologic abnormalities, and neuropsychiatric symptoms. An accurate way to predict response would help patients make informed decisions about antiviral treatment, taking into account the risk and possible benefit for individual patients.

GENETIC POLYMORPHISM AND HEPATITIS C VIRUS INFECTION

Genome-wide association studies have identified single-nucleotide polymorphisms in the IL28B gene that are associated with differences in response to hepatitis C treatment.⁸

Studying 565,759 polymorphisms in 1,137 patients, researchers at Duke University identified a single-nucleotide polymorphism at location rs12979860 in IL28B (Figure 1) that was strongly associated with response to combination therapy with pegylated interferon and ribavirin.⁸ The chance of cure with this standard treatment is twice as high in patients who are homozygous for cytosine in this location (the CC genotype) than in those who are heterozygous (CT) or homozygous for thymine in this location (the TT genotype) (Table 1).

Adding one of the new protease inhibitors, telaprevir or boceprevir, to the standard hepatitis C treatment substantially improves the cure rates in all three IL28B genotypes, but especially in people with CT or TT, in whom the response rate almost triples with the addition of one of these drugs. Those with the CC genotype (who are more likely to be cured with pegylated interferon and ribavirin alone) also achieve an increase (although minimal) in cure rates when a protease inhibitor is included in the regimen (TABLE 1).^13–15 Thus, it remains unclear if adding a protease inhibitor to pegylated interferon plus ribavirin in patients with the IL28B CC genotype translates into added effectiveness worth the additional cost of the protease inhibitor in previously untreated patients.

Additionally, the effect of the IL28B genotype on telaprevir-based triple therapy has been disputed in more recent studies. In a subgroup analysis of the results of a trial that evaluated telaprevir in the treatment of hepatitis C, researchers found that sustained virologic response rates were significantly higher in the telaprevir group, and this was similar across the different IL28B polymorphisms.¹⁶

The favorable IL28B CC genotype is associated with higher rates of rapid virologic response to antiviral therapy.^13–15 Of note, almost all patients who achieve a rapid virologic response do well, with a high rate of sustained virologic response even after a shorter duration of therapy (24 vs 48 weeks). Therefore, in addition to predicting response to interferon before starting treatment, the IL28B CC genotype may also identify patients who need only a shorter duration of therapy.

Interestingly, the C allele is much more frequent in white than in African American populations, an important observation that explains the racial difference in response to hepatitis C therapy.⁸

Two other research groups, from Asia and Australia, performed independent genome-wide association studies that identified different single-nucleotide polymorphisms (eg, rs8099917) in the same IL28B gene as predictors of response to treatment in patients with hepatitis C virus infection.^17,18 These findings may be explained by linkage disequilibrium, which means that these single-nucleotide polymorphisms are found more frequently together in the same patient due to their proximity to each other. In this review, we will focus on the rs12979860 polymorphism; hence “IL28B genotype” will refer to the single-nucleotide polymorphism at rs12979860, unless otherwise specified.

The favorable CC genotype is less common in African Americans than in patients of other ethnicities.¹⁹ Moreover, although IL28B CC is associated with a better response rate to interferon-based antiviral therapy across all ethnicities, those of African American descent with the CC genotype are less likely to achieve a sustained virologic response than white or Hispanic Americans.⁸

BIOLOGIC ASSOCIATION: IL28B POLYMORPHISM AND HEPATITIS C

The interferon lambda family consists of three cytokines:

• Interleukin 29 (interferon lambda 1)
• Interleukin 28A (interferon lambda 2)
• Interleukin 28B (interferon  lambda 3).

Production of these three molecules can be triggered by viral infection, and they induce antiviral activity through both innate and adaptive immune pathways. They signal through the IL10R-IL28R receptor complex.^20–22 This receptor activates the JAK-STAT (Janus kinase-signal transducer and activator of transcription) pathway, which regulates a large number of interferon-stimulated genes, primarily through the interferon-stimulated response element (Figure 2).

A 2013 study found that interferon-stimulated gene expression levels in patients with normal livers were highest in those with the CC genotype, intermediate with CT, and lowest with TT. Interestingly, this pattern was reversed in those with hepatitis C virus infection, indicating a relationship between the IL28B genotype and gene expression before infection.23

The mechanism underlying the association between the IL28B polymorphism and response to hepatitis C treatment is not well understood. The unfavorable TT genotype seems to lead to continuous activation of a subset of interferon-stimulated genes in the presence of intracellular hepatitis C viral RNA. But this level of expression is not sufficient to eliminate the virus from the cells. Instead, it might lead to up-regulation of interferon-inhibitory molecules that suppress JAK-STAT signaling, thereby reducing sensitivity to interferon signaling. Therefore, the hepatocyte not only cannot clear the virus by itself, but also cannot induce strong interferon-stimulated gene expression when interferon is given during therapy.^20–22

The recently identified ss469425590 polymorphism, which is located in close proximity to rs12979860 in the IL28B gene, is particularly interesting, as it suggests a possible molecular mechanism. The delta G frameshift variant creates a novel gene called IFNL4, which is transiently activated in response to hepatitis C virus infection.²⁴IFNL4 stimulates STAT1 and STAT2 phosphorylation and induces the expression of interferon-stimulated genes. Increased interferon-stimulated gene expression has been shown to be associated with decreased response to pegylated interferon-ribavirin treatment. These observations suggest that the ss469425590 delta G allele is responsible for the increased activation of interferon-stimulated genes and the lower sustained virologic response rate observed in patients who receive pegylated interferon-ribavirin treatment. It is possible that the activation of interferon-stimulated genes in patients with the ss469425590 delta G/delta G genotype reduces interferon-stimulated gene responsiveness to interferon alpha, which normally activates interferon-stimulated genes and inhibits hepatitis C progression.²⁴

IL28B POLYMORPHISM AND ACUTE HEPATITIS C VIRUS INFECTION

From 70% to 80% of acute hepatitis C virus infections persist and become chronic, while 20% to 30% spontaneously resolve. Epidemiologic, viral, and host factors have been associated with the differences in viral clearance or persistence, and studies have found that a strong host immune response against the virus favors viral clearance. Thus, variation in the genes involved in the immune response may contribute to one’s ability to clear the virus. Consistent with these observations, recent studies have shown that the polymorphism in the IL28 gene region encoding interferon lambda 3 strongly predicts spontaneous resolution of acute hepatitis C virus infection. People who have the IL28B CC genotype are three times more likely to spontaneously clear the virus than those with the CT or TT genotype (Figure 3).²⁴

IL28B POLYMORPHISM AND THE NATURAL HISTORY OF HEPATITIS C

In people in whom hepatitis C virus infection persists, up to 20% develop progressive liver fibrosis and eventually cirrhosis over 10 to 20 years.^19,25,26 The speed at which fibrosis develops in these patients is variable and unpredictable.²⁵ The relationship between IL28B polymorphisms and hepatic fibrosis in patients with chronic hepatitis C virus infection has not been clearly established, although a study indicated that in patients with a known date of infection, the IL28B genotype is not associated with progression of hepatic fibrosis.²⁷ Obstacles in this field of study are that it is difficult to determine accurately when the patient contracted the virus, and that serial liver biopsies are needed to investigate the progression of hepatic fibrosis.

Patients with chronic hepatitis C virus infection are also at higher risk of hepatocellular carcinoma compared with the general population.²⁸ An analysis of explanted livers of patients with hepatitis C found that the prevalence of hepatocellular carcinoma in those with the unfavorable TT genotype was significantly higher than with the other genotypes.²⁹ Similarly, an earlier study demonstrated that patients with hepatitis C-associated hepatocellular carcinoma carried the T allele more frequently.³⁰ As with other aspects of IL28B associations with hepatitis C, these findings indicate that the C allele confers a certain degree of protection.

An important implication of these relationships is that they may eventually help identify patients at greater risk, who therefore need earlier intervention.

IL28B POLYMORPHISM AND LIVER TRANSPLANTATION

Hepatitis C virus infection always recurs after liver transplantation, with serious consequences that include cirrhosis and liver failure. Recurrent hepatitis C virus infection has become an important reason for repeat transplantation in the United States.

Results of treatment with pegylated interferon and ribavirin for recurrent hepatitis C after liver transplantation have been disappointing, with response rates lower than 30% and significant side effects.³¹ Identifying the factors that predict the response to therapy allows for better selection of treatment candidates.

Similar to the way the IL28B genotype predicts response to antiviral therapy in the nontransplant setting, the IL28B genotypes of both the recipient and the donor are strongly and independently associated with response to interferon-based treatment in patients with hepatitis C after liver transplantation. The IL28B CC genotype in either the recipient or the donor is associated with a higher rate of response to pegylated interferon and ribavirin combination therapy after liver transplantation.^30,32 For example, the response rate to therapy after liver transplantation reaches 86% in CC-donor and CC-recipient livers, compared with 0% in TT-donor and TT-recipient livers.

Additionally, the IL28B genotype of the recipient may determine the severity of histologic recurrence of hepatitis C, as indicated by progressive hepatic fibrosis. A recipient IL28B TT genotype is associated with more severe histologic recurrence of hepatitis C.³³

These data suggest that CC donor livers might be preferentially allocated to patients with hepatitis C virus infection.

IL28B AND OTHER FACTORS IN HEPATITIS C VIRUS INFECTION

Although it is tempting to think that the IL28B polymorphism is the sole predictor of response to antiviral therapy, it is but one of several known factors in the virus and the host.

While IL28B polymorphisms are the most important predictor of sustained virologic response with an interferon-based regimen, a rapid virologic response (undetectable viral load at 4 weeks) had superior predictive value and specificity in one study.³⁴ In fact, for patients with chronic hepatitis C infection who achieved a rapid virologic response with pegylated interferon and ribavirin, the IL28B polymorphism had no effect on the rate of sustained virologic response. However, it did predict a sustained virologic response in the group who did not achieve rapid virologic response.

In a study of patients with acute hepatitis C infection,³⁵ jaundice and the IL28 rs12979860 CC genotype both predicted spontaneous clearance. The best predictor of viral persistence was the combination of the CT or TT genotype plus the absence of jaundice, which had a predictive value of 98%.

IL28B AND THE FUTURE OF HEPATITIS C VIRUS THERAPY

New oral agents were recently approved for treating hepatitis C. As of November 2014, these included simeprevir, sofosbuvir, and ledipasvir.

Simeprevir is a second-generation NS3/4A protease inhibitor approved for use in combination with pegylated interferon and ribavirin. A recent phase 3 trial evaluating simeprevir in patients who had relapsed after prior therapy found sustained virologic response rates to be higher with simeprevir than with placebo, irrespective of IL28B status.³⁶ This finding was similar to that of a trial of telaprevir.¹⁶

Sofosbuvir is a nucleotide analogue NS5B polymerase inhibitor that becomes incorporated into the growing RNA, inducing a chain termination event.³⁷ In phase 3 trials,^38,39 researchers found an initial rapid decrease in viral load for patients treated with this agent regardless of IL28B status.

In the NEUTRINO trial (Sofosbuvir With Peginterferon Alfa 2a and Ribavirin for 12 Weeks in Treatment-Naive Subjects With Chronic Genotype 1, 4, 5, or 6 HCV Infection),³⁸ which used sofusbuvir in combination with interferon and ribavirin, the rate of sustained virologic response was higher in those with the favorable CC genotype (98%) than with a non-CC genotype (87%).

In COSMOS (A Study of TMC435 in Combination With PSI-7977 [GS7977] in Chronic Hepatitis C Genotype 1-Infected Prior Null Responders to Peginterferon/Ribavirin Therapy or HCV Treatment-Naive Patients),³⁹ which used a combination of simeprevir, sofosbuvir, and ribavirin, the rate of sustained virologic response was higher in those with the CC genotype (100%) than with the TT genotype (83%; Table 1).

These new medications have radically changed the landscape of hepatitis C therapy and have also unlocked the potential for developing completely interferon-free regimens.

Other new interferon-free regimens such as ledipasvir, daclatasvir, and asunaprevir promise high rates of sustained virologic response, which makes the utility of testing for IL28B polymorphisms to predict sustained virologic response very much diminished (Table 1).^40,41 However, these new drugs are expected to be expensive, and IL28B polymorphisms may be used to identify candidates who are more likely to respond to pegylated interferon and ribavirin, particularly in resource-poor settings and in developing countries. Additionally, patients who have contraindications to these newer therapies will still likely need an interferon-based regimen, and thus the IL28B polymorphism will still be important in predicting treatment response and prognosis.

IL28B WILL STILL BE RELEVANT IN THE INTERFERON-FREE AGE

The IL28B polymorphism is a strong predictor of spontaneous clearance of hepatitis C virus and responsiveness to interferon-based therapy, and testing for it has demonstrated a great potential to improve patient care. IL28B testing has become available for clinical use and may optimize the outcome of hepatitis C treatment by helping us to select the best treatment for individual patients and minimizing the duration of therapy and the side effects associated with interferon-based antiviral medications.

As newer therapies have shifted toward interferon-free regimens that offer very high sustained virologic response rates, the usefulness of  IL28B polymorphism as a clinical test to predict the response rate to antiviral therapy is minimized substantially. It may remain clinically relevant in resource-poor settings and in developing countries, especially in light of the potentially prohibitive costs of the newer regimens, and for patients in whom these treatments are contraindicated. This does not minimize the lesson we learned from the discovery of the IL28B gene and the impact on our understanding of the pathogenesis of hepatitis C virus infection.

What a difference a single nucleotide can make! The human genome contains more than 3 billion base pairs. Yet having a different nucleotide in only one pair can make a big difference in how we respond to a disease or its treatment.

Specifically, in hepatitis C virus infection, people born with the nucleotide cytosine (C) at location rs12979860 in both alleles of the gene that codes for interleukin 28B (the IL28B CC genotype) can count themselves luckier than those born with thymine (T) in this location in one of their alleles (the CT genotype) or both of their alleles (the TT genotype). Those with the CC genotype are more likely to clear the virus spontaneously, and even if the infection persists, it is less likely to progress to liver cancer and more likely to respond to treatment with interferon.

Here, we review the IL28B polymorphism and its implications in treating hepatitis C.

GENETIC POLYMORPHISM AND HUMAN DISEASE

Of the 3 billion base pairs of nucleotides, fewer than 1% differ between individuals, but this 1% is responsible for the diversity of human beings. Differences in genetic sequences among individuals are called genetic polymorphisms. A single-nucleotide polymorphism is a DNA sequence variation that occurs in a single nucleotide in the genome. For example, two sequenced DNA fragments from different individuals, AAGCCTA and AAGCTTA, contain a difference in a single nucleotide.

Genetic variations such as these underlie some of the differences in our susceptibility to disease, the severity of illness we develop, and our response to treatments. Therefore, identifying genetic polymorphisms may shed light on biologic pathways involved in diseases and may uncover new targets for therapy.¹

Genome-wide association studies have looked at hundreds of thousands of single-nucleotide polymorphisms to try to identify most of the common genetic differences among people and relate them to common chronic diseases such as coronary artery disease,² type 2 diabetes,³ stroke,⁴ breast cancer,⁵ rheumatoid arthritis,⁶ Alzheimer disease,⁷ and, more recently, hepatitis C virus infection.⁸

HEPATITIS C VIRUS: A MAJOR CAUSE OF LIVER DISEASE

Hepatitis C virus infection is a major cause of chronic liver disease and hepatocellular carcinoma and has become the most common indication for liver transplantation in the United States.⁹

This virus has six distinct genotypes throughout the world, with multiple subtypes in each genotype. (A genotype is a classification of a virus based on its RNA.⁹) In this review, we will focus on genotype 1; hence, “hepatitis C virus” will refer to hepatitis C virus genotype 1.

Our knowledge of the biology, pathogenesis, and treatment of hepatitis C has been advancing. Originally, fewer than 50% of patients responded to therapy with the combination of pegylated interferon and ribavirin,^10,11 but since 2011 the response rate has increased to approximately 70% with the approval of the protease inhibitors telaprevir and boceprevir, used in combination with pegylated interferon and ribavirin.^12–15

Unfortunately, interferon-based treatment is often complicated by side effects such as fatigue, influenza-like symptoms, hematologic abnormalities, and neuropsychiatric symptoms. An accurate way to predict response would help patients make informed decisions about antiviral treatment, taking into account the risk and possible benefit for individual patients.

GENETIC POLYMORPHISM AND HEPATITIS C VIRUS INFECTION

Genome-wide association studies have identified single-nucleotide polymorphisms in the IL28B gene that are associated with differences in response to hepatitis C treatment.⁸

Studying 565,759 polymorphisms in 1,137 patients, researchers at Duke University identified a single-nucleotide polymorphism at location rs12979860 in IL28B (Figure 1) that was strongly associated with response to combination therapy with pegylated interferon and ribavirin.⁸ The chance of cure with this standard treatment is twice as high in patients who are homozygous for cytosine in this location (the CC genotype) than in those who are heterozygous (CT) or homozygous for thymine in this location (the TT genotype) (Table 1).

Adding one of the new protease inhibitors, telaprevir or boceprevir, to the standard hepatitis C treatment substantially improves the cure rates in all three IL28B genotypes, but especially in people with CT or TT, in whom the response rate almost triples with the addition of one of these drugs. Those with the CC genotype (who are more likely to be cured with pegylated interferon and ribavirin alone) also achieve an increase (although minimal) in cure rates when a protease inhibitor is included in the regimen (TABLE 1).^13–15 Thus, it remains unclear if adding a protease inhibitor to pegylated interferon plus ribavirin in patients with the IL28B CC genotype translates into added effectiveness worth the additional cost of the protease inhibitor in previously untreated patients.

Additionally, the effect of the IL28B genotype on telaprevir-based triple therapy has been disputed in more recent studies. In a subgroup analysis of the results of a trial that evaluated telaprevir in the treatment of hepatitis C, researchers found that sustained virologic response rates were significantly higher in the telaprevir group, and this was similar across the different IL28B polymorphisms.¹⁶

The favorable IL28B CC genotype is associated with higher rates of rapid virologic response to antiviral therapy.^13–15 Of note, almost all patients who achieve a rapid virologic response do well, with a high rate of sustained virologic response even after a shorter duration of therapy (24 vs 48 weeks). Therefore, in addition to predicting response to interferon before starting treatment, the IL28B CC genotype may also identify patients who need only a shorter duration of therapy.

Interestingly, the C allele is much more frequent in white than in African American populations, an important observation that explains the racial difference in response to hepatitis C therapy.⁸

Two other research groups, from Asia and Australia, performed independent genome-wide association studies that identified different single-nucleotide polymorphisms (eg, rs8099917) in the same IL28B gene as predictors of response to treatment in patients with hepatitis C virus infection.^17,18 These findings may be explained by linkage disequilibrium, which means that these single-nucleotide polymorphisms are found more frequently together in the same patient due to their proximity to each other. In this review, we will focus on the rs12979860 polymorphism; hence “IL28B genotype” will refer to the single-nucleotide polymorphism at rs12979860, unless otherwise specified.

The favorable CC genotype is less common in African Americans than in patients of other ethnicities.¹⁹ Moreover, although IL28B CC is associated with a better response rate to interferon-based antiviral therapy across all ethnicities, those of African American descent with the CC genotype are less likely to achieve a sustained virologic response than white or Hispanic Americans.⁸

BIOLOGIC ASSOCIATION: IL28B POLYMORPHISM AND HEPATITIS C

The interferon lambda family consists of three cytokines:

• Interleukin 29 (interferon lambda 1)
• Interleukin 28A (interferon lambda 2)
• Interleukin 28B (interferon  lambda 3).

Production of these three molecules can be triggered by viral infection, and they induce antiviral activity through both innate and adaptive immune pathways. They signal through the IL10R-IL28R receptor complex.^20–22 This receptor activates the JAK-STAT (Janus kinase-signal transducer and activator of transcription) pathway, which regulates a large number of interferon-stimulated genes, primarily through the interferon-stimulated response element (Figure 2).

A 2013 study found that interferon-stimulated gene expression levels in patients with normal livers were highest in those with the CC genotype, intermediate with CT, and lowest with TT. Interestingly, this pattern was reversed in those with hepatitis C virus infection, indicating a relationship between the IL28B genotype and gene expression before infection.23

The mechanism underlying the association between the IL28B polymorphism and response to hepatitis C treatment is not well understood. The unfavorable TT genotype seems to lead to continuous activation of a subset of interferon-stimulated genes in the presence of intracellular hepatitis C viral RNA. But this level of expression is not sufficient to eliminate the virus from the cells. Instead, it might lead to up-regulation of interferon-inhibitory molecules that suppress JAK-STAT signaling, thereby reducing sensitivity to interferon signaling. Therefore, the hepatocyte not only cannot clear the virus by itself, but also cannot induce strong interferon-stimulated gene expression when interferon is given during therapy.^20–22

The recently identified ss469425590 polymorphism, which is located in close proximity to rs12979860 in the IL28B gene, is particularly interesting, as it suggests a possible molecular mechanism. The delta G frameshift variant creates a novel gene called IFNL4, which is transiently activated in response to hepatitis C virus infection.²⁴IFNL4 stimulates STAT1 and STAT2 phosphorylation and induces the expression of interferon-stimulated genes. Increased interferon-stimulated gene expression has been shown to be associated with decreased response to pegylated interferon-ribavirin treatment. These observations suggest that the ss469425590 delta G allele is responsible for the increased activation of interferon-stimulated genes and the lower sustained virologic response rate observed in patients who receive pegylated interferon-ribavirin treatment. It is possible that the activation of interferon-stimulated genes in patients with the ss469425590 delta G/delta G genotype reduces interferon-stimulated gene responsiveness to interferon alpha, which normally activates interferon-stimulated genes and inhibits hepatitis C progression.²⁴

IL28B POLYMORPHISM AND ACUTE HEPATITIS C VIRUS INFECTION

From 70% to 80% of acute hepatitis C virus infections persist and become chronic, while 20% to 30% spontaneously resolve. Epidemiologic, viral, and host factors have been associated with the differences in viral clearance or persistence, and studies have found that a strong host immune response against the virus favors viral clearance. Thus, variation in the genes involved in the immune response may contribute to one’s ability to clear the virus. Consistent with these observations, recent studies have shown that the polymorphism in the IL28 gene region encoding interferon lambda 3 strongly predicts spontaneous resolution of acute hepatitis C virus infection. People who have the IL28B CC genotype are three times more likely to spontaneously clear the virus than those with the CT or TT genotype (Figure 3).²⁴

IL28B POLYMORPHISM AND THE NATURAL HISTORY OF HEPATITIS C

In people in whom hepatitis C virus infection persists, up to 20% develop progressive liver fibrosis and eventually cirrhosis over 10 to 20 years.^19,25,26 The speed at which fibrosis develops in these patients is variable and unpredictable.²⁵ The relationship between IL28B polymorphisms and hepatic fibrosis in patients with chronic hepatitis C virus infection has not been clearly established, although a study indicated that in patients with a known date of infection, the IL28B genotype is not associated with progression of hepatic fibrosis.²⁷ Obstacles in this field of study are that it is difficult to determine accurately when the patient contracted the virus, and that serial liver biopsies are needed to investigate the progression of hepatic fibrosis.

Patients with chronic hepatitis C virus infection are also at higher risk of hepatocellular carcinoma compared with the general population.²⁸ An analysis of explanted livers of patients with hepatitis C found that the prevalence of hepatocellular carcinoma in those with the unfavorable TT genotype was significantly higher than with the other genotypes.²⁹ Similarly, an earlier study demonstrated that patients with hepatitis C-associated hepatocellular carcinoma carried the T allele more frequently.³⁰ As with other aspects of IL28B associations with hepatitis C, these findings indicate that the C allele confers a certain degree of protection.

An important implication of these relationships is that they may eventually help identify patients at greater risk, who therefore need earlier intervention.

IL28B POLYMORPHISM AND LIVER TRANSPLANTATION

Hepatitis C virus infection always recurs after liver transplantation, with serious consequences that include cirrhosis and liver failure. Recurrent hepatitis C virus infection has become an important reason for repeat transplantation in the United States.

Results of treatment with pegylated interferon and ribavirin for recurrent hepatitis C after liver transplantation have been disappointing, with response rates lower than 30% and significant side effects.³¹ Identifying the factors that predict the response to therapy allows for better selection of treatment candidates.

Similar to the way the IL28B genotype predicts response to antiviral therapy in the nontransplant setting, the IL28B genotypes of both the recipient and the donor are strongly and independently associated with response to interferon-based treatment in patients with hepatitis C after liver transplantation. The IL28B CC genotype in either the recipient or the donor is associated with a higher rate of response to pegylated interferon and ribavirin combination therapy after liver transplantation.^30,32 For example, the response rate to therapy after liver transplantation reaches 86% in CC-donor and CC-recipient livers, compared with 0% in TT-donor and TT-recipient livers.

Additionally, the IL28B genotype of the recipient may determine the severity of histologic recurrence of hepatitis C, as indicated by progressive hepatic fibrosis. A recipient IL28B TT genotype is associated with more severe histologic recurrence of hepatitis C.³³

These data suggest that CC donor livers might be preferentially allocated to patients with hepatitis C virus infection.

IL28B AND OTHER FACTORS IN HEPATITIS C VIRUS INFECTION

Although it is tempting to think that the IL28B polymorphism is the sole predictor of response to antiviral therapy, it is but one of several known factors in the virus and the host.

While IL28B polymorphisms are the most important predictor of sustained virologic response with an interferon-based regimen, a rapid virologic response (undetectable viral load at 4 weeks) had superior predictive value and specificity in one study.³⁴ In fact, for patients with chronic hepatitis C infection who achieved a rapid virologic response with pegylated interferon and ribavirin, the IL28B polymorphism had no effect on the rate of sustained virologic response. However, it did predict a sustained virologic response in the group who did not achieve rapid virologic response.

In a study of patients with acute hepatitis C infection,³⁵ jaundice and the IL28 rs12979860 CC genotype both predicted spontaneous clearance. The best predictor of viral persistence was the combination of the CT or TT genotype plus the absence of jaundice, which had a predictive value of 98%.

IL28B AND THE FUTURE OF HEPATITIS C VIRUS THERAPY

New oral agents were recently approved for treating hepatitis C. As of November 2014, these included simeprevir, sofosbuvir, and ledipasvir.

Simeprevir is a second-generation NS3/4A protease inhibitor approved for use in combination with pegylated interferon and ribavirin. A recent phase 3 trial evaluating simeprevir in patients who had relapsed after prior therapy found sustained virologic response rates to be higher with simeprevir than with placebo, irrespective of IL28B status.³⁶ This finding was similar to that of a trial of telaprevir.¹⁶

Sofosbuvir is a nucleotide analogue NS5B polymerase inhibitor that becomes incorporated into the growing RNA, inducing a chain termination event.³⁷ In phase 3 trials,^38,39 researchers found an initial rapid decrease in viral load for patients treated with this agent regardless of IL28B status.

In the NEUTRINO trial (Sofosbuvir With Peginterferon Alfa 2a and Ribavirin for 12 Weeks in Treatment-Naive Subjects With Chronic Genotype 1, 4, 5, or 6 HCV Infection),³⁸ which used sofusbuvir in combination with interferon and ribavirin, the rate of sustained virologic response was higher in those with the favorable CC genotype (98%) than with a non-CC genotype (87%).

In COSMOS (A Study of TMC435 in Combination With PSI-7977 [GS7977] in Chronic Hepatitis C Genotype 1-Infected Prior Null Responders to Peginterferon/Ribavirin Therapy or HCV Treatment-Naive Patients),³⁹ which used a combination of simeprevir, sofosbuvir, and ribavirin, the rate of sustained virologic response was higher in those with the CC genotype (100%) than with the TT genotype (83%; Table 1).

These new medications have radically changed the landscape of hepatitis C therapy and have also unlocked the potential for developing completely interferon-free regimens.

Other new interferon-free regimens such as ledipasvir, daclatasvir, and asunaprevir promise high rates of sustained virologic response, which makes the utility of testing for IL28B polymorphisms to predict sustained virologic response very much diminished (Table 1).^40,41 However, these new drugs are expected to be expensive, and IL28B polymorphisms may be used to identify candidates who are more likely to respond to pegylated interferon and ribavirin, particularly in resource-poor settings and in developing countries. Additionally, patients who have contraindications to these newer therapies will still likely need an interferon-based regimen, and thus the IL28B polymorphism will still be important in predicting treatment response and prognosis.

IL28B WILL STILL BE RELEVANT IN THE INTERFERON-FREE AGE

The IL28B polymorphism is a strong predictor of spontaneous clearance of hepatitis C virus and responsiveness to interferon-based therapy, and testing for it has demonstrated a great potential to improve patient care. IL28B testing has become available for clinical use and may optimize the outcome of hepatitis C treatment by helping us to select the best treatment for individual patients and minimizing the duration of therapy and the side effects associated with interferon-based antiviral medications.

As newer therapies have shifted toward interferon-free regimens that offer very high sustained virologic response rates, the usefulness of  IL28B polymorphism as a clinical test to predict the response rate to antiviral therapy is minimized substantially. It may remain clinically relevant in resource-poor settings and in developing countries, especially in light of the potentially prohibitive costs of the newer regimens, and for patients in whom these treatments are contraindicated. This does not minimize the lesson we learned from the discovery of the IL28B gene and the impact on our understanding of the pathogenesis of hepatitis C virus infection.

The treatment of hepatitis c virus (HCV) infection is on the brink of major changes with the recent approval of the first direct-acting antiviral agents, the protease inhibitors boceprevir (Victrelis) and telaprevir (Incivek).

Both drugs were approved by the US Food and Drug Administration (FDA) Advisory Panel for Chronic Hepatitis C in May 2011 and are believed to significantly improve treatment outcomes for patients with HCV genotype 1 infection.

A MAJOR PUBLIC HEALTH PROBLEM

HCV infection is a major public health problem. Nearly 4 million people in the United States are infected.^6,7 Most patients with acute HCV infection become chronically infected, and up to 25% eventually develop cirrhosis and its complications, making HCV infection the leading indication for liver transplantation.^8–10

Chronic HCV infection has a large global impact, with 180 million people affected across all economic and social groups.¹¹ The highest prevalence of HCV has been reported in Egypt (14%), in part due to the use of inadequately sterilized needles in mass programs to treat endemic schistosomiasis. In developed countries, hepatocellular carcinoma associated with HCV has the fastest growing cancer-related death rate.¹²

CURRENTLY, FEWER THAN 50% OF PATIENTS ARE CURED

The goal of HCV treatment is to eradicate the virus. However, most infected patients (especially in the United States and Europe) are infected with HCV genotype 1, which is the most difficult genotype to treat.

Successful treatment of HCV is defined as achieving a sustained virologic response—ie, the absence of detectable HCV RNA in the serum 24 weeks after completion of therapy. Once a sustained virologic response is achieved, lifetime “cure” of HCV infection is expected in more than 99% of patients.¹³

The current standard therapy for HCV, pegylated interferon plus ribavirin for 48 weeks, is effective in only 40% to 50% of patients with genotype 1 infection.¹⁴ Therefore, assessing predictors of response before starting treatment can help select patients who are most likely to benefit from therapy.

Viral factors associated with a sustained virologic response include HCV genotypes other than genotype 1 and a low baseline viral load.

Beneficial patient-related factors include younger age, nonblack ethnicity, low body weight (≤ 75 kg), low body mass index, absence of insulin resistance, and absence of advanced fibrosis or cirrhosis.

More recently, a single-nucleotide polymorphism near the interleukin 28B (IL28B) gene, coding for interferon lambda 3, was found to be associated with a twofold difference in the rates of sustained virologic response: patients with the favorable genotype CC were two times more likely to achieve a sustained virologic response than patients with the CT or TT genotypes.^15–17

PROTEASE INHIBITORS: MECHANISM OF ACTION

NS3/4A protease inhibitors rely on the principle of end-product inhibition, in which the cleavage product of the protease (a peptide) acts to inhibit the enzyme activity; this is why they are called peptidomimetics. The active site of the NS3/4A protease is a shallow groove composed of three highly conserved amino acid residues, which may explain why protease inhibitors display high antiviral efficacy but pose a low barrier to the development of resistance.²⁰

Protease inhibitors are prone to resistance

The development of viral resistance to protease inhibitors has been a major drawback to their use in patients with chronic HCV infection.²¹

HCV is a highly variable virus with many genetically distinct but closely related quasispecies circulating in the blood at any given time. Drug-resistant, mutated variants preexist within the patient’s quasispecies, but only in small quantities because of their lesser replication fitness compared with the wild-type virus.²² When direct-acting antiviral therapy is started, the quantity of the wild-type virus decreases and the mutated virus gains replication fitness. Using protease inhibitors as monotherapy selects resistant viral populations rapidly within a few days or weeks.

HCV subtypes 1a and 1b may have different resistance profiles. With genotype 1a, some resistance-associated amino acid substitutions require only one nucleotide change, but with genotype 1b, two nucleotide changes are needed, making resistance less frequent in patients with HCV genotype 1b.²³

BOCEPREVIR

Boceprevir is a specific inhibitor of the HCV viral protease NS3/4A.

In phase 3 clinical trials, boceprevir 800 mg three times a day was used with pegylated interferon alfa-2b (PegIntron) 1.5 μg/kg/week and ribavirin (Rebetol) 600 to 1,400 mg daily according to body weight.

Before patients started taking boceprevir, they went through a 4-week lead-in phase, during which they received pegylated interferon and ribavirin. This schedule appeared to reduce the incidence of viral breakthrough in phase 2 trials, and it produced higher rates of sustained virologic response and lower relapse rates compared with triple therapy without a lead-in phase.

Rapid virologic response was defined as undetectable HCV RNA at week 4 of boceprevir therapy (week 8 of the whole regimen).

Boceprevir in previously untreated patients with HCV genotype 1: The SPRINT-2 trial

The Serine Protease Inhibitor Therapy 2 (SPRINT-2) trial¹ included more than 1,000 previously untreated adults with HCV genotype 1 infection (938 nonblack patients and 159 black patients; two other nonblack patients did not receive any study drug and were not included in the analysis). In this double-blind trial, patients were randomized into three groups:

• The control group received the standard of care with pegylated interferon and ribavirin for 48 weeks
• The response-guided therapy group received boceprevir plus pegylated interferon and ribavirin for 24 weeks after the 4-week lead-in phase; if HCV RNA was undetectable from week 8 to week 24, treatment was considered complete, but if HCV RNA was detectable at any point from week 8 to week 24, pegylated interferon and ribavirin were continued for a total of 48 weeks.
• The fixed-duration therapy group received boceprevir, pegylated interferon, and ribavirin for 44 weeks after the lead-in period.

The rate of relapse was 8% and 9% in the boceprevir groups vs 23% in the control group. Patients in the boceprevir groups who had a decrease in HCV RNA of less than 1 log₁₀ during the lead-in phase were found to have a significantly higher rate of boceprevirresistant variants than those who achieved a decrease of HCV RNA of 1 log₁₀ or more.

Boceprevir in previously treated patients with HCV genotype 1: The RESPOND-2 trial

The Retreatment With HCV Serine Protease Inhibitor Boceprevir and PegIntron/Rebetol 2) (RESPOND-2) trial² was designed to assess the efficacy of combined boceprevir, pegylated interferon, and ribavirin for repeat treatment of patients with HCV genotype 1. These patients had previously undergone standard treatment and had a reduction of 2 log₁₀ or more in HCV RNA after 12 weeks of therapy but with detectable HCV RNA during the therapy period or had had a relapse (defined as undetectable HCV RNA at the end of a previous course of therapy with HCV RNA positivity thereafter). Importantly, null-responders (those who had a reduction of less than 2 log₁₀ in HCV RNA after 12 weeks of therapy) were excluded from this trial.

After a lead-in period of interferon-ribavirin treatment for 4 weeks, 403 patients were assigned to one of three treatment groups:

• Pegylated interferon and ribavirin for 44 weeks (the control group)
• Boceprevir, pegylated interferon, and ribavirin in a response-guided regimen
• Boceprevir, pegylated interferon, and ribavirin for 44 weeks (the fixed-duration group).

Sustained virologic response was achieved in only 21% of patients in the control group. Adding boceprevir increased the rate to 59% in the response-guided therapy group and to 67% in the fixed-duration group. Previous relapsers had better rates than partial responders (69%–75% vs 40%–52%).

Importantly, patients who had a poor response to pegylated interferon and ribavirin during the lead-in phase (defined as having less than a 1-log decrease in the virus before starting boceprevir) had significantly lower rates of sustained virologic response and higher rates of resistance-associated virus variants.

Side effects of boceprevir

Overall, boceprevir is well tolerated. The most common side effects of triple therapy are those usually seen with pegylated interferon and ribavirin, such as flulike symptoms and fatigue (Table 2). However, anemia was more frequent in the boceprevir groups in both SPRINT-2 and RESPOND-2 (45%–50% compared with 20%–29% in the control groups). Erythropoietin was allowed in these studies and was used in about 40% of patients.

The other common side effect associated with boceprevir was dysgeusia (alteration of taste). Dysgeusia was reported by approximately 40% of patients; however, most dysgeusia events were mild to moderate in intensity and did not lead to treatment cessation.

In the SPRINT-2 trial,¹ the study drugs had to be discontinued in 12% to 16% of patients in the boceprevir groups because of adverse events, which was similar to the rate (16%) in the control group. Erythropoietin was allowed in this trial, and it was used in 43% of patients in the boceprevir groups compared with 24% in the control group, with discontinuation owing to anemia occurring in 2% and 1% of cases, respectively.

TELAPREVIR

Telaprevir, the other protease NS3/4A inhibitor, has also shown efficacy over current standard therapy in phase 3 clinical trials. It was used in a dose of 750 mg three times a day with pegylated interferon alfa-2a (Pegasys) 180 μg per week and ribavirin (Copegus) 1,000 to 1,200 mg daily according to body weight. A lead-in phase with pegylated interferon and ribavirin was not applied with telaprevir, as it was in the boceprevir trials. Extended rapid virologic response was defined as an undetectable HCV RNA at weeks 4 and 12 of therapy.

Telaprevir in previously untreated patients with HCV genotype 1

The ADVANCE study³ was a double-blind randomized trial assessing the efficacy and safety of telaprevir in combination with pegylated interferon and ribavirin in more than 1,000 previously untreated patients. The three treatment groups received:

• Telaprevir, pegylated interferon, and ribavirin for 8 weeks, followed by pegylated interferon and ribavirin alone for 16 weeks in patients who achieved an extended rapid virologic response (total duration of 24 weeks) or 40 weeks in patients who did not (total duration of 48 weeks)
• Telaprevir, pegylated interferon, and ribavirin for 12 weeks, followed by pegylated interferon-ribavirin alone for 12 (total of 24 weeks) or 36 weeks (total of 48 weeks) according to extended rapid virologic response
• Standard care with pegylated interferon and ribavirin for 48 weeks.

The rate of sustained virologic response was 69% in the group that received telaprevir for 8 weeks and 75% in the group that received it for 12 weeks compared with 44% in the control group (P < .0001 for both) (Table 2). Patients infected with HCV genotype 1b had a higher sustained virologic response rate (79%) than those infected with HCV genotype 1a (71%).

Sustained virologic response rates were lower in black patients and patients with bridging fibrosis or cirrhosis, but were still significantly higher in the telaprevir groups than in the control group. The results of this subset analysis were limited by small numbers of patients in each category.

In total, 57% of those who received telaprevir for 8 weeks and 58% of those who received it for 12 weeks achieved an extended rapid virologic response and were able to cut the duration of their therapy in half (from 48 weeks to 24 weeks).

The relapse rates were 9% in the telaprevir groups and 28% in the control group.

The rate of virologic failure was lower in patients who received triple therapy than in those who received interferon-ribavirin alone (8% in the group that got telaprevir for 12 weeks and 13% in the group that got it for 8 weeks, vs 32% in the control group). The failure rate was also lower in patients with HCV genotype 1b infection than in those with genotype 1a.

The ILLUMINATE study⁴ (Illustrating the Effects of Combination Therapy With Telaprevir) investigated whether longer duration of treatment than that given in the ADVANCE trial increased the rate of sustained virologic response. Previously untreated patients received telaprevir, interferon, and ribavirin for 12 weeks, and those who achieved an extended rapid virologic response were randomized at week 20 to continue interferonribavirin treatment for 24 or 48 weeks of total treatment.

The sustained virologic response rates in patients who achieved an extended rapid virologic response were 92% in the group that received pegylated interferon and ribavirin for 12 weeks, and 88% in those who received it for 48 weeks. Thus, the results of this study support the use of response-guided therapy for telaprevir-based regimens.

In this phase 3 placebo-controlled trial,⁵ 622 patients with prior relapse, partial response, or null response were randomly allocated into one of three groups:

• Telaprevir for 12 weeks plus pegylated interferon and ribavirin for 48 weeks
• Lead-in for 4 weeks followed by 12 weeks of triple therapy and another 32 weeks of pegylated interferon and ribavirin
• Pegylated interferon and ribavirin for 48 weeks (the control group).

The overall sustained virologic response rates were 66% and 64%, respectively, in the telaprevir groups vs 17% in the control group (P < .0001). The sustained virologic response rates in the telaprevir groups were 83% to 88% in prior relapsers, 54% to 59% in partial responders, and 29% to 33% in null-responders. Of note, patients did not benefit from the lead-in phase.

This was the only trial to investigate the response to triple therapy in null-responders, a group in which treatment has been considered hopeless. A response rate of approximately 31% was encouraging, especially if we compare it with the 5% response rate achieved with the current standard of care with pegylated interferon and ribavirin.

Telaprevir side effects

As with boceprevir-based triple therapy, the most common adverse events were related to pegylated interferon (Table 2).

Nearly 50% of patients who receive telaprevir develop a skin rash that is primarily eczematous, can be managed with topical steroids, and usually resolves when telaprevir is discontinued. Severe rashes occurred in 3% to 6% of patients in the ADVANCE trial,³ and three suspected cases of Stevens-Johnson syndrome have been reported to the FDA.

Other side effects that were more frequent with telaprevir included pruritus, nausea, diarrhea, and anemia. On average, the hemoglobin level decreased by an additional 1 g/dL in the telaprevir treatment groups compared with the groups that received only pegylated interferon-ribavirin. Erythropoietin use was not allowed in the phase 3 telaprevir studies, and anemia was managed by ribavirin dose reduction.

In the ADVANCE trial,³ study drugs were discontinued owing to adverse events in 7% to 8% of the patients in the telaprevir groups compared with 4% in the control group. In the ILLUMINATE trial,⁴ 17% of patients had to permanently discontinue all study drugs due to adverse events.

FDA-APPROVED TREATMENT REGIMENS FOR BOCEPREVIR AND TELAPREVIR

For treatment algorithms, see the eFigures that accompany this article online.

Boceprevir in previously untreated patients

• Week 0—Start pegylated interferon and ribavirin
• Week 4—Add boceprevir
• Week 8—Measure HCV RNA
• Week 12—Measure HCV RNA; stop treatment if it is more than 100 IU/mL
• Week 24—Measure HCV RNA; stop treatment if it is detectable
• Week 28—Stop all treatment if HCV RNA was undetectable at weeks 8 and 24
• Week 36—Measure HCV RNA; stop boceprevir
• Week 48—Stop all treatment (eFigure 1).

Boceprevir in previously treated patients

• Week 0—Start pegylated interferon and ribavirin
• Week 4—Add boceprevir
• Week 8—Measure HCV RNA
• Week 12—Measure HCV RNA; stop treatment if it is more than 100 IU/mL
• Week 24—Measure HCV RNA; stop treatment if it is detectable
• Week 36—if HCV RNA was not detectable at week 8, stop all treatment now; if HCV RNA was detectable at week 8, stop boceprevir now but continue pegylated interferon and ribavirin
• Week 48—Stop all treatment (eFigure 2).

Telaprevir in previously untreated patients and prior relapsers

• Week 0—start telaprevir, pegylated interferon, and ribavirin
• Week 4—measure HCV RNA; stop all treatment if it is more than 1,000 IU/mL
• Week 12—Stop telaprevir; measure HCV RNA; stop all treatment if HCV RNA is more than 1,000 IU/mL
• Week 24—Stop pegylated interferon and ribavirin if HCV RNA was undetectable at week 12; measure HCV RNA and stop treatment if it is detectable; otherwise, continue pegylated interferon and ribavirin
• Week 48—Stop all treatment (eFigure 3).

Telaprevir in patients who previously achieved a partial or null response

• Week 0—Start telaprevir, pegylated interferon, and ribavirin
• Week 4—Measure HCV RNA; stop treatment if it is more than 1,000 IU/mL
• Week 12—Measure HCV RNA; stop all treatment if it is more than 1,000 IU/mL; if less than 1,000 IU/mL then stop telaprevir but continue pegylated interferon and ribavirin
• Week 24—Measure HCV RNA; stop treatment if HCV RNA is detectable
• Week 48—Stop all treatment (eFigure 4).

Drug interactions with boceprevir and telaprevir

Both boceprevir and telaprevir inhibit cytochrome P450 3A (CYP3A) and thus are contraindicated in combination with drugs highly dependent on CYP3A for clearance and with drugs for which elevated plasma concentrations are associated with serious adverse events, such as atorvastatin (Lipitor), simvastatin (Zocor), sildenafil (Viagra), midazolam (Versed), and St. John’s wort. Giving potent inducers of CYP3A with boceprevir or telaprevir may lead to lower exposure and loss of efficacy of both protease inhibitors.

EMERGING THERAPIES FOR HCV

Thanks to a better understanding of the biology of HCV infection, the effort to develop new therapeutic agents started to focus on targeting specific steps of the viral life cycle, including attachment, entry into cells, replication, and release.²⁴

Currently, more than 50 clinical trials are evaluating new direct-acting antivirals to treat HCV infection.²⁵ Monoclonal and polyclonal antibodies that target the molecular process involved in HCV attachment and entry are being developed.²⁶ The nonstructural protein NS5B (RNA polymerase) is intimately involved in viral replication and represents a promising target.²⁷ Several nucleosides and nonnucleoside protease inhibitors have already entered clinical trials.

The low fidelity of the HCV replication machinery leads to a very high mutation rate, thus enabling the virus to quickly develop mutations that resist agents targeting viral enzymes.²⁸ Therefore, a novel approach is to target host cofactors that are essential for HCV replication. An intriguing study by Lanford et al²⁹ demonstrated that antagonizing microRNA-122 (the most abundant microRNA in the liver and an essential cofactor for viral RNA replication) by the oligonucleotide SPC3649 caused marked and prolonged reduction of HCV viremia in chronically infected chimpanzees.²⁹

Although we are still in the early stages of drug development, the future holds great promise for newer drugs to improve the sustained virologic response, shorten the duration of treatment, improve tolerability with interferon-sparing regimens, and decrease viral resistance.

FUTURE PERSPECTIVES

With the introduction of the first direct-acting antiviral medications for HCV (boceprevir and telaprevir), 2011 will be marked as the year that changed hepatitis C treatment for the better. Triple therapy with pegylated interferon, ribavirin, and either boceprevir or telaprevir has the potential for increasing the rate of sustained virologic response to around 70% in previously untreated patients and 65% in previously treated patients who are infected with HCV genotype 1. The IL28B polymorphisms appear to play a role in the rate of sustained virologic response achieved with triple therapy, with preliminary data showing a better response rate in patients who have the CC genotype.¹⁷

These drugs will add up to $50,000 to the cost of treating hepatitis C virus infection, depending on the drug used and the length of treatment. However, they may be well worth it if they prevent liver failure and the need for transplantation.

Many questions remain, such as how to use these new regimens to treat special patient populations—for example, those with a recurrence of HCV infection after liver transplantation, those co-infected with HCV and human immunodeficiency virus, and those infected with HCV genotypes other than genotype 1.

Other direct-acting antiviral agents that specifically target the replication cycle of HCV are currently in clinical development. In fact, the future has already started with the release of the Interferon-Free Regimen for the Management of HCV (INFORM-1) study results.³⁰ This was the first trial to evaluate an interferon-free regimen for patients with chronic HCV infection using two direct-acting antiviral drugs (the protease inhibitor danoprevir and the polymerase inhibitor RG7128), with promising results.

The treatment of hepatitis c virus (HCV) infection is on the brink of major changes with the recent approval of the first direct-acting antiviral agents, the protease inhibitors boceprevir (Victrelis) and telaprevir (Incivek).

Both drugs were approved by the US Food and Drug Administration (FDA) Advisory Panel for Chronic Hepatitis C in May 2011 and are believed to significantly improve treatment outcomes for patients with HCV genotype 1 infection.

A MAJOR PUBLIC HEALTH PROBLEM

HCV infection is a major public health problem. Nearly 4 million people in the United States are infected.^6,7 Most patients with acute HCV infection become chronically infected, and up to 25% eventually develop cirrhosis and its complications, making HCV infection the leading indication for liver transplantation.^8–10

Chronic HCV infection has a large global impact, with 180 million people affected across all economic and social groups.¹¹ The highest prevalence of HCV has been reported in Egypt (14%), in part due to the use of inadequately sterilized needles in mass programs to treat endemic schistosomiasis. In developed countries, hepatocellular carcinoma associated with HCV has the fastest growing cancer-related death rate.¹²

CURRENTLY, FEWER THAN 50% OF PATIENTS ARE CURED

The goal of HCV treatment is to eradicate the virus. However, most infected patients (especially in the United States and Europe) are infected with HCV genotype 1, which is the most difficult genotype to treat.

Successful treatment of HCV is defined as achieving a sustained virologic response—ie, the absence of detectable HCV RNA in the serum 24 weeks after completion of therapy. Once a sustained virologic response is achieved, lifetime “cure” of HCV infection is expected in more than 99% of patients.¹³

The current standard therapy for HCV, pegylated interferon plus ribavirin for 48 weeks, is effective in only 40% to 50% of patients with genotype 1 infection.¹⁴ Therefore, assessing predictors of response before starting treatment can help select patients who are most likely to benefit from therapy.

Viral factors associated with a sustained virologic response include HCV genotypes other than genotype 1 and a low baseline viral load.

Beneficial patient-related factors include younger age, nonblack ethnicity, low body weight (≤ 75 kg), low body mass index, absence of insulin resistance, and absence of advanced fibrosis or cirrhosis.

More recently, a single-nucleotide polymorphism near the interleukin 28B (IL28B) gene, coding for interferon lambda 3, was found to be associated with a twofold difference in the rates of sustained virologic response: patients with the favorable genotype CC were two times more likely to achieve a sustained virologic response than patients with the CT or TT genotypes.^15–17

PROTEASE INHIBITORS: MECHANISM OF ACTION

NS3/4A protease inhibitors rely on the principle of end-product inhibition, in which the cleavage product of the protease (a peptide) acts to inhibit the enzyme activity; this is why they are called peptidomimetics. The active site of the NS3/4A protease is a shallow groove composed of three highly conserved amino acid residues, which may explain why protease inhibitors display high antiviral efficacy but pose a low barrier to the development of resistance.²⁰

Protease inhibitors are prone to resistance

The development of viral resistance to protease inhibitors has been a major drawback to their use in patients with chronic HCV infection.²¹

HCV is a highly variable virus with many genetically distinct but closely related quasispecies circulating in the blood at any given time. Drug-resistant, mutated variants preexist within the patient’s quasispecies, but only in small quantities because of their lesser replication fitness compared with the wild-type virus.²² When direct-acting antiviral therapy is started, the quantity of the wild-type virus decreases and the mutated virus gains replication fitness. Using protease inhibitors as monotherapy selects resistant viral populations rapidly within a few days or weeks.

HCV subtypes 1a and 1b may have different resistance profiles. With genotype 1a, some resistance-associated amino acid substitutions require only one nucleotide change, but with genotype 1b, two nucleotide changes are needed, making resistance less frequent in patients with HCV genotype 1b.²³

BOCEPREVIR

Boceprevir is a specific inhibitor of the HCV viral protease NS3/4A.

In phase 3 clinical trials, boceprevir 800 mg three times a day was used with pegylated interferon alfa-2b (PegIntron) 1.5 μg/kg/week and ribavirin (Rebetol) 600 to 1,400 mg daily according to body weight.

Before patients started taking boceprevir, they went through a 4-week lead-in phase, during which they received pegylated interferon and ribavirin. This schedule appeared to reduce the incidence of viral breakthrough in phase 2 trials, and it produced higher rates of sustained virologic response and lower relapse rates compared with triple therapy without a lead-in phase.

Rapid virologic response was defined as undetectable HCV RNA at week 4 of boceprevir therapy (week 8 of the whole regimen).

Boceprevir in previously untreated patients with HCV genotype 1: The SPRINT-2 trial

The Serine Protease Inhibitor Therapy 2 (SPRINT-2) trial¹ included more than 1,000 previously untreated adults with HCV genotype 1 infection (938 nonblack patients and 159 black patients; two other nonblack patients did not receive any study drug and were not included in the analysis). In this double-blind trial, patients were randomized into three groups:

• The control group received the standard of care with pegylated interferon and ribavirin for 48 weeks
• The response-guided therapy group received boceprevir plus pegylated interferon and ribavirin for 24 weeks after the 4-week lead-in phase; if HCV RNA was undetectable from week 8 to week 24, treatment was considered complete, but if HCV RNA was detectable at any point from week 8 to week 24, pegylated interferon and ribavirin were continued for a total of 48 weeks.
• The fixed-duration therapy group received boceprevir, pegylated interferon, and ribavirin for 44 weeks after the lead-in period.

The rate of relapse was 8% and 9% in the boceprevir groups vs 23% in the control group. Patients in the boceprevir groups who had a decrease in HCV RNA of less than 1 log₁₀ during the lead-in phase were found to have a significantly higher rate of boceprevirresistant variants than those who achieved a decrease of HCV RNA of 1 log₁₀ or more.

Boceprevir in previously treated patients with HCV genotype 1: The RESPOND-2 trial

The Retreatment With HCV Serine Protease Inhibitor Boceprevir and PegIntron/Rebetol 2) (RESPOND-2) trial² was designed to assess the efficacy of combined boceprevir, pegylated interferon, and ribavirin for repeat treatment of patients with HCV genotype 1. These patients had previously undergone standard treatment and had a reduction of 2 log₁₀ or more in HCV RNA after 12 weeks of therapy but with detectable HCV RNA during the therapy period or had had a relapse (defined as undetectable HCV RNA at the end of a previous course of therapy with HCV RNA positivity thereafter). Importantly, null-responders (those who had a reduction of less than 2 log₁₀ in HCV RNA after 12 weeks of therapy) were excluded from this trial.

After a lead-in period of interferon-ribavirin treatment for 4 weeks, 403 patients were assigned to one of three treatment groups:

• Pegylated interferon and ribavirin for 44 weeks (the control group)
• Boceprevir, pegylated interferon, and ribavirin in a response-guided regimen
• Boceprevir, pegylated interferon, and ribavirin for 44 weeks (the fixed-duration group).

Sustained virologic response was achieved in only 21% of patients in the control group. Adding boceprevir increased the rate to 59% in the response-guided therapy group and to 67% in the fixed-duration group. Previous relapsers had better rates than partial responders (69%–75% vs 40%–52%).

Importantly, patients who had a poor response to pegylated interferon and ribavirin during the lead-in phase (defined as having less than a 1-log decrease in the virus before starting boceprevir) had significantly lower rates of sustained virologic response and higher rates of resistance-associated virus variants.

Side effects of boceprevir

Overall, boceprevir is well tolerated. The most common side effects of triple therapy are those usually seen with pegylated interferon and ribavirin, such as flulike symptoms and fatigue (Table 2). However, anemia was more frequent in the boceprevir groups in both SPRINT-2 and RESPOND-2 (45%–50% compared with 20%–29% in the control groups). Erythropoietin was allowed in these studies and was used in about 40% of patients.

The other common side effect associated with boceprevir was dysgeusia (alteration of taste). Dysgeusia was reported by approximately 40% of patients; however, most dysgeusia events were mild to moderate in intensity and did not lead to treatment cessation.

In the SPRINT-2 trial,¹ the study drugs had to be discontinued in 12% to 16% of patients in the boceprevir groups because of adverse events, which was similar to the rate (16%) in the control group. Erythropoietin was allowed in this trial, and it was used in 43% of patients in the boceprevir groups compared with 24% in the control group, with discontinuation owing to anemia occurring in 2% and 1% of cases, respectively.

TELAPREVIR

Telaprevir, the other protease NS3/4A inhibitor, has also shown efficacy over current standard therapy in phase 3 clinical trials. It was used in a dose of 750 mg three times a day with pegylated interferon alfa-2a (Pegasys) 180 μg per week and ribavirin (Copegus) 1,000 to 1,200 mg daily according to body weight. A lead-in phase with pegylated interferon and ribavirin was not applied with telaprevir, as it was in the boceprevir trials. Extended rapid virologic response was defined as an undetectable HCV RNA at weeks 4 and 12 of therapy.

Telaprevir in previously untreated patients with HCV genotype 1

The ADVANCE study³ was a double-blind randomized trial assessing the efficacy and safety of telaprevir in combination with pegylated interferon and ribavirin in more than 1,000 previously untreated patients. The three treatment groups received:

• Telaprevir, pegylated interferon, and ribavirin for 8 weeks, followed by pegylated interferon and ribavirin alone for 16 weeks in patients who achieved an extended rapid virologic response (total duration of 24 weeks) or 40 weeks in patients who did not (total duration of 48 weeks)
• Telaprevir, pegylated interferon, and ribavirin for 12 weeks, followed by pegylated interferon-ribavirin alone for 12 (total of 24 weeks) or 36 weeks (total of 48 weeks) according to extended rapid virologic response
• Standard care with pegylated interferon and ribavirin for 48 weeks.

The rate of sustained virologic response was 69% in the group that received telaprevir for 8 weeks and 75% in the group that received it for 12 weeks compared with 44% in the control group (P < .0001 for both) (Table 2). Patients infected with HCV genotype 1b had a higher sustained virologic response rate (79%) than those infected with HCV genotype 1a (71%).

Sustained virologic response rates were lower in black patients and patients with bridging fibrosis or cirrhosis, but were still significantly higher in the telaprevir groups than in the control group. The results of this subset analysis were limited by small numbers of patients in each category.

In total, 57% of those who received telaprevir for 8 weeks and 58% of those who received it for 12 weeks achieved an extended rapid virologic response and were able to cut the duration of their therapy in half (from 48 weeks to 24 weeks).

The relapse rates were 9% in the telaprevir groups and 28% in the control group.

The rate of virologic failure was lower in patients who received triple therapy than in those who received interferon-ribavirin alone (8% in the group that got telaprevir for 12 weeks and 13% in the group that got it for 8 weeks, vs 32% in the control group). The failure rate was also lower in patients with HCV genotype 1b infection than in those with genotype 1a.

The ILLUMINATE study⁴ (Illustrating the Effects of Combination Therapy With Telaprevir) investigated whether longer duration of treatment than that given in the ADVANCE trial increased the rate of sustained virologic response. Previously untreated patients received telaprevir, interferon, and ribavirin for 12 weeks, and those who achieved an extended rapid virologic response were randomized at week 20 to continue interferonribavirin treatment for 24 or 48 weeks of total treatment.

The sustained virologic response rates in patients who achieved an extended rapid virologic response were 92% in the group that received pegylated interferon and ribavirin for 12 weeks, and 88% in those who received it for 48 weeks. Thus, the results of this study support the use of response-guided therapy for telaprevir-based regimens.

In this phase 3 placebo-controlled trial,⁵ 622 patients with prior relapse, partial response, or null response were randomly allocated into one of three groups:

• Telaprevir for 12 weeks plus pegylated interferon and ribavirin for 48 weeks
• Lead-in for 4 weeks followed by 12 weeks of triple therapy and another 32 weeks of pegylated interferon and ribavirin
• Pegylated interferon and ribavirin for 48 weeks (the control group).

The overall sustained virologic response rates were 66% and 64%, respectively, in the telaprevir groups vs 17% in the control group (P < .0001). The sustained virologic response rates in the telaprevir groups were 83% to 88% in prior relapsers, 54% to 59% in partial responders, and 29% to 33% in null-responders. Of note, patients did not benefit from the lead-in phase.

This was the only trial to investigate the response to triple therapy in null-responders, a group in which treatment has been considered hopeless. A response rate of approximately 31% was encouraging, especially if we compare it with the 5% response rate achieved with the current standard of care with pegylated interferon and ribavirin.

Telaprevir side effects

As with boceprevir-based triple therapy, the most common adverse events were related to pegylated interferon (Table 2).

Nearly 50% of patients who receive telaprevir develop a skin rash that is primarily eczematous, can be managed with topical steroids, and usually resolves when telaprevir is discontinued. Severe rashes occurred in 3% to 6% of patients in the ADVANCE trial,³ and three suspected cases of Stevens-Johnson syndrome have been reported to the FDA.

Other side effects that were more frequent with telaprevir included pruritus, nausea, diarrhea, and anemia. On average, the hemoglobin level decreased by an additional 1 g/dL in the telaprevir treatment groups compared with the groups that received only pegylated interferon-ribavirin. Erythropoietin use was not allowed in the phase 3 telaprevir studies, and anemia was managed by ribavirin dose reduction.

In the ADVANCE trial,³ study drugs were discontinued owing to adverse events in 7% to 8% of the patients in the telaprevir groups compared with 4% in the control group. In the ILLUMINATE trial,⁴ 17% of patients had to permanently discontinue all study drugs due to adverse events.

FDA-APPROVED TREATMENT REGIMENS FOR BOCEPREVIR AND TELAPREVIR

For treatment algorithms, see the eFigures that accompany this article online.

Boceprevir in previously untreated patients

• Week 0—Start pegylated interferon and ribavirin
• Week 4—Add boceprevir
• Week 8—Measure HCV RNA
• Week 12—Measure HCV RNA; stop treatment if it is more than 100 IU/mL
• Week 24—Measure HCV RNA; stop treatment if it is detectable
• Week 28—Stop all treatment if HCV RNA was undetectable at weeks 8 and 24
• Week 36—Measure HCV RNA; stop boceprevir
• Week 48—Stop all treatment (eFigure 1).

Boceprevir in previously treated patients

• Week 0—Start pegylated interferon and ribavirin
• Week 4—Add boceprevir
• Week 8—Measure HCV RNA
• Week 12—Measure HCV RNA; stop treatment if it is more than 100 IU/mL
• Week 24—Measure HCV RNA; stop treatment if it is detectable
• Week 36—if HCV RNA was not detectable at week 8, stop all treatment now; if HCV RNA was detectable at week 8, stop boceprevir now but continue pegylated interferon and ribavirin
• Week 48—Stop all treatment (eFigure 2).

Telaprevir in previously untreated patients and prior relapsers

• Week 0—start telaprevir, pegylated interferon, and ribavirin
• Week 4—measure HCV RNA; stop all treatment if it is more than 1,000 IU/mL
• Week 12—Stop telaprevir; measure HCV RNA; stop all treatment if HCV RNA is more than 1,000 IU/mL
• Week 24—Stop pegylated interferon and ribavirin if HCV RNA was undetectable at week 12; measure HCV RNA and stop treatment if it is detectable; otherwise, continue pegylated interferon and ribavirin
• Week 48—Stop all treatment (eFigure 3).

Telaprevir in patients who previously achieved a partial or null response

• Week 0—Start telaprevir, pegylated interferon, and ribavirin
• Week 4—Measure HCV RNA; stop treatment if it is more than 1,000 IU/mL
• Week 12—Measure HCV RNA; stop all treatment if it is more than 1,000 IU/mL; if less than 1,000 IU/mL then stop telaprevir but continue pegylated interferon and ribavirin
• Week 24—Measure HCV RNA; stop treatment if HCV RNA is detectable
• Week 48—Stop all treatment (eFigure 4).

Drug interactions with boceprevir and telaprevir

Both boceprevir and telaprevir inhibit cytochrome P450 3A (CYP3A) and thus are contraindicated in combination with drugs highly dependent on CYP3A for clearance and with drugs for which elevated plasma concentrations are associated with serious adverse events, such as atorvastatin (Lipitor), simvastatin (Zocor), sildenafil (Viagra), midazolam (Versed), and St. John’s wort. Giving potent inducers of CYP3A with boceprevir or telaprevir may lead to lower exposure and loss of efficacy of both protease inhibitors.

EMERGING THERAPIES FOR HCV

Thanks to a better understanding of the biology of HCV infection, the effort to develop new therapeutic agents started to focus on targeting specific steps of the viral life cycle, including attachment, entry into cells, replication, and release.²⁴

Currently, more than 50 clinical trials are evaluating new direct-acting antivirals to treat HCV infection.²⁵ Monoclonal and polyclonal antibodies that target the molecular process involved in HCV attachment and entry are being developed.²⁶ The nonstructural protein NS5B (RNA polymerase) is intimately involved in viral replication and represents a promising target.²⁷ Several nucleosides and nonnucleoside protease inhibitors have already entered clinical trials.

The low fidelity of the HCV replication machinery leads to a very high mutation rate, thus enabling the virus to quickly develop mutations that resist agents targeting viral enzymes.²⁸ Therefore, a novel approach is to target host cofactors that are essential for HCV replication. An intriguing study by Lanford et al²⁹ demonstrated that antagonizing microRNA-122 (the most abundant microRNA in the liver and an essential cofactor for viral RNA replication) by the oligonucleotide SPC3649 caused marked and prolonged reduction of HCV viremia in chronically infected chimpanzees.²⁹

Although we are still in the early stages of drug development, the future holds great promise for newer drugs to improve the sustained virologic response, shorten the duration of treatment, improve tolerability with interferon-sparing regimens, and decrease viral resistance.

FUTURE PERSPECTIVES

With the introduction of the first direct-acting antiviral medications for HCV (boceprevir and telaprevir), 2011 will be marked as the year that changed hepatitis C treatment for the better. Triple therapy with pegylated interferon, ribavirin, and either boceprevir or telaprevir has the potential for increasing the rate of sustained virologic response to around 70% in previously untreated patients and 65% in previously treated patients who are infected with HCV genotype 1. The IL28B polymorphisms appear to play a role in the rate of sustained virologic response achieved with triple therapy, with preliminary data showing a better response rate in patients who have the CC genotype.¹⁷

These drugs will add up to $50,000 to the cost of treating hepatitis C virus infection, depending on the drug used and the length of treatment. However, they may be well worth it if they prevent liver failure and the need for transplantation.

Many questions remain, such as how to use these new regimens to treat special patient populations—for example, those with a recurrence of HCV infection after liver transplantation, those co-infected with HCV and human immunodeficiency virus, and those infected with HCV genotypes other than genotype 1.

Other direct-acting antiviral agents that specifically target the replication cycle of HCV are currently in clinical development. In fact, the future has already started with the release of the Interferon-Free Regimen for the Management of HCV (INFORM-1) study results.³⁰ This was the first trial to evaluate an interferon-free regimen for patients with chronic HCV infection using two direct-acting antiviral drugs (the protease inhibitor danoprevir and the polymerase inhibitor RG7128), with promising results.

The treatment of hepatitis c virus (HCV) infection is on the brink of major changes with the recent approval of the first direct-acting antiviral agents, the protease inhibitors boceprevir (Victrelis) and telaprevir (Incivek).

Both drugs were approved by the US Food and Drug Administration (FDA) Advisory Panel for Chronic Hepatitis C in May 2011 and are believed to significantly improve treatment outcomes for patients with HCV genotype 1 infection.

A MAJOR PUBLIC HEALTH PROBLEM

HCV infection is a major public health problem. Nearly 4 million people in the United States are infected.^6,7 Most patients with acute HCV infection become chronically infected, and up to 25% eventually develop cirrhosis and its complications, making HCV infection the leading indication for liver transplantation.^8–10

Chronic HCV infection has a large global impact, with 180 million people affected across all economic and social groups.¹¹ The highest prevalence of HCV has been reported in Egypt (14%), in part due to the use of inadequately sterilized needles in mass programs to treat endemic schistosomiasis. In developed countries, hepatocellular carcinoma associated with HCV has the fastest growing cancer-related death rate.¹²

CURRENTLY, FEWER THAN 50% OF PATIENTS ARE CURED

The goal of HCV treatment is to eradicate the virus. However, most infected patients (especially in the United States and Europe) are infected with HCV genotype 1, which is the most difficult genotype to treat.

Successful treatment of HCV is defined as achieving a sustained virologic response—ie, the absence of detectable HCV RNA in the serum 24 weeks after completion of therapy. Once a sustained virologic response is achieved, lifetime “cure” of HCV infection is expected in more than 99% of patients.¹³

The current standard therapy for HCV, pegylated interferon plus ribavirin for 48 weeks, is effective in only 40% to 50% of patients with genotype 1 infection.¹⁴ Therefore, assessing predictors of response before starting treatment can help select patients who are most likely to benefit from therapy.

Viral factors associated with a sustained virologic response include HCV genotypes other than genotype 1 and a low baseline viral load.

Beneficial patient-related factors include younger age, nonblack ethnicity, low body weight (≤ 75 kg), low body mass index, absence of insulin resistance, and absence of advanced fibrosis or cirrhosis.

More recently, a single-nucleotide polymorphism near the interleukin 28B (IL28B) gene, coding for interferon lambda 3, was found to be associated with a twofold difference in the rates of sustained virologic response: patients with the favorable genotype CC were two times more likely to achieve a sustained virologic response than patients with the CT or TT genotypes.^15–17

PROTEASE INHIBITORS: MECHANISM OF ACTION

NS3/4A protease inhibitors rely on the principle of end-product inhibition, in which the cleavage product of the protease (a peptide) acts to inhibit the enzyme activity; this is why they are called peptidomimetics. The active site of the NS3/4A protease is a shallow groove composed of three highly conserved amino acid residues, which may explain why protease inhibitors display high antiviral efficacy but pose a low barrier to the development of resistance.²⁰

Protease inhibitors are prone to resistance

The development of viral resistance to protease inhibitors has been a major drawback to their use in patients with chronic HCV infection.²¹

HCV is a highly variable virus with many genetically distinct but closely related quasispecies circulating in the blood at any given time. Drug-resistant, mutated variants preexist within the patient’s quasispecies, but only in small quantities because of their lesser replication fitness compared with the wild-type virus.²² When direct-acting antiviral therapy is started, the quantity of the wild-type virus decreases and the mutated virus gains replication fitness. Using protease inhibitors as monotherapy selects resistant viral populations rapidly within a few days or weeks.

HCV subtypes 1a and 1b may have different resistance profiles. With genotype 1a, some resistance-associated amino acid substitutions require only one nucleotide change, but with genotype 1b, two nucleotide changes are needed, making resistance less frequent in patients with HCV genotype 1b.²³

BOCEPREVIR

Boceprevir is a specific inhibitor of the HCV viral protease NS3/4A.

In phase 3 clinical trials, boceprevir 800 mg three times a day was used with pegylated interferon alfa-2b (PegIntron) 1.5 μg/kg/week and ribavirin (Rebetol) 600 to 1,400 mg daily according to body weight.

Before patients started taking boceprevir, they went through a 4-week lead-in phase, during which they received pegylated interferon and ribavirin. This schedule appeared to reduce the incidence of viral breakthrough in phase 2 trials, and it produced higher rates of sustained virologic response and lower relapse rates compared with triple therapy without a lead-in phase.

Rapid virologic response was defined as undetectable HCV RNA at week 4 of boceprevir therapy (week 8 of the whole regimen).

Boceprevir in previously untreated patients with HCV genotype 1: The SPRINT-2 trial

The Serine Protease Inhibitor Therapy 2 (SPRINT-2) trial¹ included more than 1,000 previously untreated adults with HCV genotype 1 infection (938 nonblack patients and 159 black patients; two other nonblack patients did not receive any study drug and were not included in the analysis). In this double-blind trial, patients were randomized into three groups:

• The control group received the standard of care with pegylated interferon and ribavirin for 48 weeks
• The response-guided therapy group received boceprevir plus pegylated interferon and ribavirin for 24 weeks after the 4-week lead-in phase; if HCV RNA was undetectable from week 8 to week 24, treatment was considered complete, but if HCV RNA was detectable at any point from week 8 to week 24, pegylated interferon and ribavirin were continued for a total of 48 weeks.
• The fixed-duration therapy group received boceprevir, pegylated interferon, and ribavirin for 44 weeks after the lead-in period.

The rate of relapse was 8% and 9% in the boceprevir groups vs 23% in the control group. Patients in the boceprevir groups who had a decrease in HCV RNA of less than 1 log₁₀ during the lead-in phase were found to have a significantly higher rate of boceprevirresistant variants than those who achieved a decrease of HCV RNA of 1 log₁₀ or more.

Boceprevir in previously treated patients with HCV genotype 1: The RESPOND-2 trial

The Retreatment With HCV Serine Protease Inhibitor Boceprevir and PegIntron/Rebetol 2) (RESPOND-2) trial² was designed to assess the efficacy of combined boceprevir, pegylated interferon, and ribavirin for repeat treatment of patients with HCV genotype 1. These patients had previously undergone standard treatment and had a reduction of 2 log₁₀ or more in HCV RNA after 12 weeks of therapy but with detectable HCV RNA during the therapy period or had had a relapse (defined as undetectable HCV RNA at the end of a previous course of therapy with HCV RNA positivity thereafter). Importantly, null-responders (those who had a reduction of less than 2 log₁₀ in HCV RNA after 12 weeks of therapy) were excluded from this trial.

After a lead-in period of interferon-ribavirin treatment for 4 weeks, 403 patients were assigned to one of three treatment groups:

• Pegylated interferon and ribavirin for 44 weeks (the control group)
• Boceprevir, pegylated interferon, and ribavirin in a response-guided regimen
• Boceprevir, pegylated interferon, and ribavirin for 44 weeks (the fixed-duration group).

Sustained virologic response was achieved in only 21% of patients in the control group. Adding boceprevir increased the rate to 59% in the response-guided therapy group and to 67% in the fixed-duration group. Previous relapsers had better rates than partial responders (69%–75% vs 40%–52%).

Importantly, patients who had a poor response to pegylated interferon and ribavirin during the lead-in phase (defined as having less than a 1-log decrease in the virus before starting boceprevir) had significantly lower rates of sustained virologic response and higher rates of resistance-associated virus variants.

Side effects of boceprevir

Overall, boceprevir is well tolerated. The most common side effects of triple therapy are those usually seen with pegylated interferon and ribavirin, such as flulike symptoms and fatigue (Table 2). However, anemia was more frequent in the boceprevir groups in both SPRINT-2 and RESPOND-2 (45%–50% compared with 20%–29% in the control groups). Erythropoietin was allowed in these studies and was used in about 40% of patients.

The other common side effect associated with boceprevir was dysgeusia (alteration of taste). Dysgeusia was reported by approximately 40% of patients; however, most dysgeusia events were mild to moderate in intensity and did not lead to treatment cessation.

In the SPRINT-2 trial,¹ the study drugs had to be discontinued in 12% to 16% of patients in the boceprevir groups because of adverse events, which was similar to the rate (16%) in the control group. Erythropoietin was allowed in this trial, and it was used in 43% of patients in the boceprevir groups compared with 24% in the control group, with discontinuation owing to anemia occurring in 2% and 1% of cases, respectively.

TELAPREVIR

Telaprevir, the other protease NS3/4A inhibitor, has also shown efficacy over current standard therapy in phase 3 clinical trials. It was used in a dose of 750 mg three times a day with pegylated interferon alfa-2a (Pegasys) 180 μg per week and ribavirin (Copegus) 1,000 to 1,200 mg daily according to body weight. A lead-in phase with pegylated interferon and ribavirin was not applied with telaprevir, as it was in the boceprevir trials. Extended rapid virologic response was defined as an undetectable HCV RNA at weeks 4 and 12 of therapy.

Telaprevir in previously untreated patients with HCV genotype 1

The ADVANCE study³ was a double-blind randomized trial assessing the efficacy and safety of telaprevir in combination with pegylated interferon and ribavirin in more than 1,000 previously untreated patients. The three treatment groups received:

• Telaprevir, pegylated interferon, and ribavirin for 8 weeks, followed by pegylated interferon and ribavirin alone for 16 weeks in patients who achieved an extended rapid virologic response (total duration of 24 weeks) or 40 weeks in patients who did not (total duration of 48 weeks)
• Telaprevir, pegylated interferon, and ribavirin for 12 weeks, followed by pegylated interferon-ribavirin alone for 12 (total of 24 weeks) or 36 weeks (total of 48 weeks) according to extended rapid virologic response
• Standard care with pegylated interferon and ribavirin for 48 weeks.

The rate of sustained virologic response was 69% in the group that received telaprevir for 8 weeks and 75% in the group that received it for 12 weeks compared with 44% in the control group (P < .0001 for both) (Table 2). Patients infected with HCV genotype 1b had a higher sustained virologic response rate (79%) than those infected with HCV genotype 1a (71%).

Sustained virologic response rates were lower in black patients and patients with bridging fibrosis or cirrhosis, but were still significantly higher in the telaprevir groups than in the control group. The results of this subset analysis were limited by small numbers of patients in each category.

In total, 57% of those who received telaprevir for 8 weeks and 58% of those who received it for 12 weeks achieved an extended rapid virologic response and were able to cut the duration of their therapy in half (from 48 weeks to 24 weeks).

The relapse rates were 9% in the telaprevir groups and 28% in the control group.

The rate of virologic failure was lower in patients who received triple therapy than in those who received interferon-ribavirin alone (8% in the group that got telaprevir for 12 weeks and 13% in the group that got it for 8 weeks, vs 32% in the control group). The failure rate was also lower in patients with HCV genotype 1b infection than in those with genotype 1a.

The ILLUMINATE study⁴ (Illustrating the Effects of Combination Therapy With Telaprevir) investigated whether longer duration of treatment than that given in the ADVANCE trial increased the rate of sustained virologic response. Previously untreated patients received telaprevir, interferon, and ribavirin for 12 weeks, and those who achieved an extended rapid virologic response were randomized at week 20 to continue interferonribavirin treatment for 24 or 48 weeks of total treatment.

The sustained virologic response rates in patients who achieved an extended rapid virologic response were 92% in the group that received pegylated interferon and ribavirin for 12 weeks, and 88% in those who received it for 48 weeks. Thus, the results of this study support the use of response-guided therapy for telaprevir-based regimens.

In this phase 3 placebo-controlled trial,⁵ 622 patients with prior relapse, partial response, or null response were randomly allocated into one of three groups:

• Telaprevir for 12 weeks plus pegylated interferon and ribavirin for 48 weeks
• Lead-in for 4 weeks followed by 12 weeks of triple therapy and another 32 weeks of pegylated interferon and ribavirin
• Pegylated interferon and ribavirin for 48 weeks (the control group).

The overall sustained virologic response rates were 66% and 64%, respectively, in the telaprevir groups vs 17% in the control group (P < .0001). The sustained virologic response rates in the telaprevir groups were 83% to 88% in prior relapsers, 54% to 59% in partial responders, and 29% to 33% in null-responders. Of note, patients did not benefit from the lead-in phase.

This was the only trial to investigate the response to triple therapy in null-responders, a group in which treatment has been considered hopeless. A response rate of approximately 31% was encouraging, especially if we compare it with the 5% response rate achieved with the current standard of care with pegylated interferon and ribavirin.

Telaprevir side effects

As with boceprevir-based triple therapy, the most common adverse events were related to pegylated interferon (Table 2).

Nearly 50% of patients who receive telaprevir develop a skin rash that is primarily eczematous, can be managed with topical steroids, and usually resolves when telaprevir is discontinued. Severe rashes occurred in 3% to 6% of patients in the ADVANCE trial,³ and three suspected cases of Stevens-Johnson syndrome have been reported to the FDA.

Other side effects that were more frequent with telaprevir included pruritus, nausea, diarrhea, and anemia. On average, the hemoglobin level decreased by an additional 1 g/dL in the telaprevir treatment groups compared with the groups that received only pegylated interferon-ribavirin. Erythropoietin use was not allowed in the phase 3 telaprevir studies, and anemia was managed by ribavirin dose reduction.

In the ADVANCE trial,³ study drugs were discontinued owing to adverse events in 7% to 8% of the patients in the telaprevir groups compared with 4% in the control group. In the ILLUMINATE trial,⁴ 17% of patients had to permanently discontinue all study drugs due to adverse events.

FDA-APPROVED TREATMENT REGIMENS FOR BOCEPREVIR AND TELAPREVIR

For treatment algorithms, see the eFigures that accompany this article online.

Boceprevir in previously untreated patients

• Week 0—Start pegylated interferon and ribavirin
• Week 4—Add boceprevir
• Week 8—Measure HCV RNA
• Week 12—Measure HCV RNA; stop treatment if it is more than 100 IU/mL
• Week 24—Measure HCV RNA; stop treatment if it is detectable
• Week 28—Stop all treatment if HCV RNA was undetectable at weeks 8 and 24
• Week 36—Measure HCV RNA; stop boceprevir
• Week 48—Stop all treatment (eFigure 1).

Boceprevir in previously treated patients

• Week 0—Start pegylated interferon and ribavirin
• Week 4—Add boceprevir
• Week 8—Measure HCV RNA
• Week 12—Measure HCV RNA; stop treatment if it is more than 100 IU/mL
• Week 24—Measure HCV RNA; stop treatment if it is detectable
• Week 36—if HCV RNA was not detectable at week 8, stop all treatment now; if HCV RNA was detectable at week 8, stop boceprevir now but continue pegylated interferon and ribavirin
• Week 48—Stop all treatment (eFigure 2).

Telaprevir in previously untreated patients and prior relapsers

• Week 0—start telaprevir, pegylated interferon, and ribavirin
• Week 4—measure HCV RNA; stop all treatment if it is more than 1,000 IU/mL
• Week 12—Stop telaprevir; measure HCV RNA; stop all treatment if HCV RNA is more than 1,000 IU/mL
• Week 24—Stop pegylated interferon and ribavirin if HCV RNA was undetectable at week 12; measure HCV RNA and stop treatment if it is detectable; otherwise, continue pegylated interferon and ribavirin
• Week 48—Stop all treatment (eFigure 3).

Telaprevir in patients who previously achieved a partial or null response

• Week 0—Start telaprevir, pegylated interferon, and ribavirin
• Week 4—Measure HCV RNA; stop treatment if it is more than 1,000 IU/mL
• Week 12—Measure HCV RNA; stop all treatment if it is more than 1,000 IU/mL; if less than 1,000 IU/mL then stop telaprevir but continue pegylated interferon and ribavirin
• Week 24—Measure HCV RNA; stop treatment if HCV RNA is detectable
• Week 48—Stop all treatment (eFigure 4).

Drug interactions with boceprevir and telaprevir

Both boceprevir and telaprevir inhibit cytochrome P450 3A (CYP3A) and thus are contraindicated in combination with drugs highly dependent on CYP3A for clearance and with drugs for which elevated plasma concentrations are associated with serious adverse events, such as atorvastatin (Lipitor), simvastatin (Zocor), sildenafil (Viagra), midazolam (Versed), and St. John’s wort. Giving potent inducers of CYP3A with boceprevir or telaprevir may lead to lower exposure and loss of efficacy of both protease inhibitors.

EMERGING THERAPIES FOR HCV

Thanks to a better understanding of the biology of HCV infection, the effort to develop new therapeutic agents started to focus on targeting specific steps of the viral life cycle, including attachment, entry into cells, replication, and release.²⁴

Currently, more than 50 clinical trials are evaluating new direct-acting antivirals to treat HCV infection.²⁵ Monoclonal and polyclonal antibodies that target the molecular process involved in HCV attachment and entry are being developed.²⁶ The nonstructural protein NS5B (RNA polymerase) is intimately involved in viral replication and represents a promising target.²⁷ Several nucleosides and nonnucleoside protease inhibitors have already entered clinical trials.

The low fidelity of the HCV replication machinery leads to a very high mutation rate, thus enabling the virus to quickly develop mutations that resist agents targeting viral enzymes.²⁸ Therefore, a novel approach is to target host cofactors that are essential for HCV replication. An intriguing study by Lanford et al²⁹ demonstrated that antagonizing microRNA-122 (the most abundant microRNA in the liver and an essential cofactor for viral RNA replication) by the oligonucleotide SPC3649 caused marked and prolonged reduction of HCV viremia in chronically infected chimpanzees.²⁹

Although we are still in the early stages of drug development, the future holds great promise for newer drugs to improve the sustained virologic response, shorten the duration of treatment, improve tolerability with interferon-sparing regimens, and decrease viral resistance.

FUTURE PERSPECTIVES

With the introduction of the first direct-acting antiviral medications for HCV (boceprevir and telaprevir), 2011 will be marked as the year that changed hepatitis C treatment for the better. Triple therapy with pegylated interferon, ribavirin, and either boceprevir or telaprevir has the potential for increasing the rate of sustained virologic response to around 70% in previously untreated patients and 65% in previously treated patients who are infected with HCV genotype 1. The IL28B polymorphisms appear to play a role in the rate of sustained virologic response achieved with triple therapy, with preliminary data showing a better response rate in patients who have the CC genotype.¹⁷

These drugs will add up to $50,000 to the cost of treating hepatitis C virus infection, depending on the drug used and the length of treatment. However, they may be well worth it if they prevent liver failure and the need for transplantation.

Many questions remain, such as how to use these new regimens to treat special patient populations—for example, those with a recurrence of HCV infection after liver transplantation, those co-infected with HCV and human immunodeficiency virus, and those infected with HCV genotypes other than genotype 1.

Other direct-acting antiviral agents that specifically target the replication cycle of HCV are currently in clinical development. In fact, the future has already started with the release of the Interferon-Free Regimen for the Management of HCV (INFORM-1) study results.³⁰ This was the first trial to evaluate an interferon-free regimen for patients with chronic HCV infection using two direct-acting antiviral drugs (the protease inhibitor danoprevir and the polymerase inhibitor RG7128), with promising results.

A 25-year-old man presented to his primary care physician with generalized malaise. His symptoms started around 2 months earlier with progressive fatigue, nausea, decreased appetite, and weight loss (15 lb in 2 months). He denied having fever, chills, night sweats, abdominal pain, diarrhea, melena, or hematochezia.

His medical history was remarkable only for depression, well controlled with sertraline (Zoloft), which he started taking 3 years ago. He was not taking any other prescribed, over-the-counter, or herbal medications.

He had no family history of cancer or liver disease. He did not smoke and rarely drank alcohol. He had never used recreational drugs. He was sexually active with one female partner, used condoms for protection, and had never been diagnosed with a sexually transmitted disease. He had not traveled recently and had not been exposed to any pet.

The patient’s laboratory values on admission are shown in Table 1. Of note, his serum alkaline phosphatase level was 1,307 U/L (reference range 40–150 U/L).

LIVER TESTS CAN NARROW THE DIAGNOSIS

The most commonly used laboratory tests of the liver can be classified into those that measure either:

• Liver synthetic function (eg, the serum albumin and bilirubin concentrations and the prothrombin time) or
• Liver damage, as reflected by the serum concentrations of the enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, and gamma-glutamyltransferase (GGT).^1,2

ALT and AST are normally concentrated in the hepatocytes and thus, when present in the serum in elevated concentrations, are markers of liver cell injury. The serum levels of these enzymes start to increase within a few hours of liver cell injury as they leak out of the cells via the damaged cell membrane. AST is less liver-specific than ALT, since AST levels can be elevated not only in liver injury but also in muscle, cardiac, and red blood cell injury.^3,4

Alkaline phosphatase is actually a heterogeneous group of enzymes found mainly in liver and bone cells. Hepatic alkaline phosphatase is concentrated near the biliary canalicular membrane of the hepatocyte. Accordingly, increased levels of hepatic alkaline phosphatase are mainly seen in liver diseases that predominantly affect the biliary system.³

GGT is also concentrated in hepatic biliary epithelial cells, and thus GGT elevation is another marker of hepatobiliary disease. In fact, measuring the GGT level can help to determine whether an isolated elevation of alkaline phosphatase is due to liver injury.^2,3

Accordingly, liver diseases can be classified into two broad categories:

• Hepatocellular injury, in which the primary injury occurs to the hepatocytes
• Cholestatic injury, in which the primary injury is to the bile ducts.

In the former, elevated levels of ALT and AST predominate, while in the latter, elevated alkaline phosphatase is the main finding.³

WHAT TEST NEXT FOR OUR PATIENT?

1. What is the next most appropriate diagnostic step for our patient?

• Liver biopsy
• Ultrasonography of the liver
• Computed tomography (CT) of the liver
• Observation

Our patient has an elevated GGT level, which suggests that his elevated alkaline phosphatase is of hepatic rather than bony origin. Moreover, a serum alkaline phosphatase level that is elevated out of proportion to the aminotransferase levels reflects cholestatic liver injury.

CASE CONTINUED: ULTRASONOGRAPHY IS MOSTLY NORMAL

Ultrasonography of the right upper quadrant revealed that the liver had normal echogenicity and was mildly enlarged. There was no focal hepatic lesion. The gallbladder appeared normal, with no stones or sludge. No dilated intrahepatic or extrahepatic biliary ducts were seen. The common bile duct measured 4 mm. A small amount of ascites not amenable to paracentesis was present.

Thus, in the absence of biliary dilation on ultrasonography, we are dealing with an intrahepatic cholestatic process.

CAUSES OF CHOLESTATIC LIVER DISEASE

Viral hepatitis

Viral hepatitis most often produces a hepatocellular pattern of injury (ie, AST and ALT elevations predominate). However, in rare cases it can cause a cholestatic pattern of injury.

Our patient subsequently had serologic tests for viral hepatitis, including hepatitis A, B, and C, and the results were negative.

Autoimmune liver disease

The three most common forms of autoimmune liver disease are autoimmune hepatitis, primary biliary cirrhosis, and primary sclerosing cholangitis.

Autoimmune hepatitis is characterized by high serum ALT and AST levels, whereas primary biliary cirrhosis and primary sclerosing cholangitis are associated with predominant elevations of alkaline phosphatase, since they are cholestatic disorders.

Our patient’s alkaline phosphatase level was much higher than his ALT and AST levels, making the latter two diseases more likely.

Primary biliary cirrhosis (and autoimmune hepatitis) are associated with autoantibodies in the serum, such as antinuclear antibody, smooth muscle antibody, and antimitochondrial antibody.

Our patient subsequently was tested for these antibodies, and the results were negative.

Primary sclerosing cholangitis usually affects the extrahepatic biliary system. Thus, if it is present, abnormalities should be seen on imaging.

As mentioned previously, no dilated intrahepatic or extrahepatic biliary ducts were seen on ultrasonography in our patient. Moreover, primary sclerosing cholangitis is associated with inflammatory bowel disease, particularly ulcerative colitis, which our patient did not have.

Drug-induced liver injury

Drug-induced liver injury is a common cause of cholestatic liver disease. However, our patient was not taking any prescribed, over-the-counter, or herbal medications. Additionally, he denied heavy alcohol use.

Infiltrative disorders

Infiltrative disorders such as amyloidosis, sarcoidosis, or lymphoma should be considered in the differential diagnosis of cholestatic liver disease. A clue to a possible infiltrative process is a markedly elevated level of alkaline phosphatase with a mildly increased serum bilirubin concentration, both of which our patient had.

AFTER ULTRASONOGRAPHY, WHAT IS THE NEXT STEP?

2. Which of the following is the next most appropriate diagnostic test for our patient?

• Endoscopic retrograde cholangiopancreatography (ERCP)
• Magnetic resonance cholangiopancreatography (MRCP)
• Liver biopsy
• CT of the abdomen

Figure 1 shows a proposed algorithm for evaluating increased alkaline phosphatase levels.

If there is no biliary duct dilation on ultrasonography, then abnormal levels of alkaline phosphatase most likely represent an intrahepatic pattern of cholestatic liver injury. Therefore, additional imaging with CT or magnetic resonance imaging is of limited diagnostic value. ERCP is used today for therapy rather than diagnosis, so its use is limited to patients known to have dilated biliary ducts on imaging. Liver biopsy, however, can provide useful findings.

Case continued: He undergoes biopsy

Our patient underwent transjugular liver biopsy. During the procedure, transjugular venography showed stenosis in the right, middle, and left hepatic veins and the hepatic portion of the inferior vena cava, consistent with Budd-Chiari syndrome.

The liver biopsy specimen was positive for extensive deposition of slight eosinophilic and amorphous material in a sinusoidal pattern in the liver parenchyma, as well as in the portal tracts, with markedly atrophic hepatocytes. Congo red birefringence confirmed the diagnosis of amyloidosis. The immunohistochemical phenotype was positive for kappa light chains, which is diagnostic for primary-type amyloidosis, also called amyloidosis of light chain composition, or AL.

Bone marrow aspiration and bone marrow biopsy were performed and showed 22% plasma cells, well above the normal range (0–2%), consistent with the diagnosis of multiple myeloma.

BUDD-CHIARI SYNDROME: A CHALLENGING DIAGNOSIS

Budd-Chiari syndrome is a rare condition characterized by obstruction of venous outflow from the liver at a site that may vary from the small hepatic veins up to the inferior vena cava or even the right atrium.^5,6 Obstruction of hepatic venous outflow leads to sinusoidal congestion and hypoxic damage of the hepatocytes.⁷ Hypoxia and necrosis of the hepatocytes result in the release of free radicals. Cirrhosis can eventually occur secondary to ischemic necrosis of hepatocytes and hepatic fibrosis.⁸

The estimated incidence of this syndrome is 1 in 2.5 million persons per year.⁷ It is more prevalent in women and young adults.⁸

Heterogeneous in its causes and manifestations

Budd-Chiari syndrome is also heterogeneous in its manifestations, which depend on the extent of the occlusion, on the acuteness of the obstruction, and on whether venous collateral circulation has developed to decompress the liver sinusoids.^9,12,13 Therefore, on the basis of its clinical manifestations, it can be classified as fulminant, acute, subacute, or chronic.^12–16

The fulminant form presents with hepatic encephalopathy within 8 weeks after the development of jaundice. The subacute form, which is the most common, has a more insidious onset in which hepatic sinusoids are decompressed by portal and hepatic venous collateral circulation. The patient usually presents with abdominal pain, ascites, hepatomegaly, nausea, vomiting, and mild jaundice. Finally the chronic form presents as complications of cirrhosis.^12–16

Imaging plays an important role in diagnosing Budd-Chiari syndrome

Imaging plays an important role in detecting and classifying Budd-Chiari syndrome.

Duplex ultrasonography is useful for detecting this syndrome and has a sensitivity and specificity of 85%.⁹

CT and magnetic resonance imaging can also help in the diagnosis by showing thrombosis, obstruction, or occlusion in the hepatic vein or the inferior vena cava.⁵

Venography is the gold standard for diagnosis. However, it should be performed only if noninvasive tests are negative or nondiagnostic and there is a high clinical suspicion of this disease.¹⁷ Budd-Chiari syndrome has a characteristic pattern on venography known as “spider web,” which is due to the formation of venous collaterals to bypass the occluded hepatic veins.⁹

Liver biopsy is not necessarily required to confirm the diagnosis of Budd-Chiari syndrome, but it can help in diagnosing the acute or subacute forms and also in ruling out other causes. Histologic findings can include centrizonal congestion, loss of hepatocytes, hemorrhage, and fibrosis.^18,19 Regenerative nodules are found in about 25% of patients.¹⁹

TREATING BUDD-CHIARI SYNDROME

The primary goal of treatment is to prevent further extension of the venous thrombosis in the hepatic veins, in their collaterals, and in the intrahepatic and extrahepatic portal venous system. Resolution of hepatic congestion improves liver perfusion and preserves function of the hepatocytes.

Anticoagulation is recommended in the early stages. Heparin therapy should be initiated and subsequently switched to warfarin with the goal of achieving an international normalized ratio of the prothrombin time of 2.0 to 2.5.^8,9,19

Thrombolysis is effective in the acute form.^20,21 Recanalization, including percutaneous or transhepatic angioplasty of localized segments of the narrowed hepatic veins or inferior vena cava, has long-term patency rates of 80% to 90%.²²

If thrombolytic therapy and angioplasty are unsuccessful, a transjugular intrahepatic portosystemic shunt or a surgical procedure (side-to-side portocaval shunt, central splenorenal shunt, or mesocaval shunt) should be considered.⁹

Liver transplantation is another treatment option in those with fulminant Budd-Chiari syndrome or advanced liver cirrhosis.⁸

PROGNOSIS HAS IMPROVED

The prognosis of Budd-Chiari syndrome has improved, thanks to both earlier diagnosis and new treatments. The 1-year survival rate, which was about 60% before 1985, has increased to more than 80% in recent cohort studies.¹⁹

Studies have shown that the Child-Pugh score, which is based on a combination of serum albumin, bilirubin, prothrombin time, encephalopathy, and ascites, can be considered as an independent prognostic factor. A lower Child-Pugh score and a younger age are associated with a good prognosis.^19,23,24 (The Child-Pugh score cannot be applied to our patient because he does not have cirrhosis.)

What happened to our patient?

Our patient was started on anticoagulation for his Budd-Chiari syndrome and on bortezomib (Velcade) and dexamethasone for his multiple myeloma. He achieved remarkable improvement in his liver function tests. Follow-up duplex ultrasonography 1 month after discharge revealed that the stenosis in the hepatic veins had resolved. He is following up with the oncology clinic for management of his multiple myeloma.

A 25-year-old man presented to his primary care physician with generalized malaise. His symptoms started around 2 months earlier with progressive fatigue, nausea, decreased appetite, and weight loss (15 lb in 2 months). He denied having fever, chills, night sweats, abdominal pain, diarrhea, melena, or hematochezia.

His medical history was remarkable only for depression, well controlled with sertraline (Zoloft), which he started taking 3 years ago. He was not taking any other prescribed, over-the-counter, or herbal medications.

He had no family history of cancer or liver disease. He did not smoke and rarely drank alcohol. He had never used recreational drugs. He was sexually active with one female partner, used condoms for protection, and had never been diagnosed with a sexually transmitted disease. He had not traveled recently and had not been exposed to any pet.

The patient’s laboratory values on admission are shown in Table 1. Of note, his serum alkaline phosphatase level was 1,307 U/L (reference range 40–150 U/L).

LIVER TESTS CAN NARROW THE DIAGNOSIS

The most commonly used laboratory tests of the liver can be classified into those that measure either:

• Liver synthetic function (eg, the serum albumin and bilirubin concentrations and the prothrombin time) or
• Liver damage, as reflected by the serum concentrations of the enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, and gamma-glutamyltransferase (GGT).^1,2

ALT and AST are normally concentrated in the hepatocytes and thus, when present in the serum in elevated concentrations, are markers of liver cell injury. The serum levels of these enzymes start to increase within a few hours of liver cell injury as they leak out of the cells via the damaged cell membrane. AST is less liver-specific than ALT, since AST levels can be elevated not only in liver injury but also in muscle, cardiac, and red blood cell injury.^3,4

Alkaline phosphatase is actually a heterogeneous group of enzymes found mainly in liver and bone cells. Hepatic alkaline phosphatase is concentrated near the biliary canalicular membrane of the hepatocyte. Accordingly, increased levels of hepatic alkaline phosphatase are mainly seen in liver diseases that predominantly affect the biliary system.³

GGT is also concentrated in hepatic biliary epithelial cells, and thus GGT elevation is another marker of hepatobiliary disease. In fact, measuring the GGT level can help to determine whether an isolated elevation of alkaline phosphatase is due to liver injury.^2,3

Accordingly, liver diseases can be classified into two broad categories:

• Hepatocellular injury, in which the primary injury occurs to the hepatocytes
• Cholestatic injury, in which the primary injury is to the bile ducts.

In the former, elevated levels of ALT and AST predominate, while in the latter, elevated alkaline phosphatase is the main finding.³

WHAT TEST NEXT FOR OUR PATIENT?

1. What is the next most appropriate diagnostic step for our patient?

• Liver biopsy
• Ultrasonography of the liver
• Computed tomography (CT) of the liver
• Observation

Our patient has an elevated GGT level, which suggests that his elevated alkaline phosphatase is of hepatic rather than bony origin. Moreover, a serum alkaline phosphatase level that is elevated out of proportion to the aminotransferase levels reflects cholestatic liver injury.

CASE CONTINUED: ULTRASONOGRAPHY IS MOSTLY NORMAL

Ultrasonography of the right upper quadrant revealed that the liver had normal echogenicity and was mildly enlarged. There was no focal hepatic lesion. The gallbladder appeared normal, with no stones or sludge. No dilated intrahepatic or extrahepatic biliary ducts were seen. The common bile duct measured 4 mm. A small amount of ascites not amenable to paracentesis was present.

Thus, in the absence of biliary dilation on ultrasonography, we are dealing with an intrahepatic cholestatic process.

CAUSES OF CHOLESTATIC LIVER DISEASE

Viral hepatitis

Viral hepatitis most often produces a hepatocellular pattern of injury (ie, AST and ALT elevations predominate). However, in rare cases it can cause a cholestatic pattern of injury.

Our patient subsequently had serologic tests for viral hepatitis, including hepatitis A, B, and C, and the results were negative.

Autoimmune liver disease

The three most common forms of autoimmune liver disease are autoimmune hepatitis, primary biliary cirrhosis, and primary sclerosing cholangitis.

Autoimmune hepatitis is characterized by high serum ALT and AST levels, whereas primary biliary cirrhosis and primary sclerosing cholangitis are associated with predominant elevations of alkaline phosphatase, since they are cholestatic disorders.

Our patient’s alkaline phosphatase level was much higher than his ALT and AST levels, making the latter two diseases more likely.

Primary biliary cirrhosis (and autoimmune hepatitis) are associated with autoantibodies in the serum, such as antinuclear antibody, smooth muscle antibody, and antimitochondrial antibody.

Our patient subsequently was tested for these antibodies, and the results were negative.

Primary sclerosing cholangitis usually affects the extrahepatic biliary system. Thus, if it is present, abnormalities should be seen on imaging.

As mentioned previously, no dilated intrahepatic or extrahepatic biliary ducts were seen on ultrasonography in our patient. Moreover, primary sclerosing cholangitis is associated with inflammatory bowel disease, particularly ulcerative colitis, which our patient did not have.

Drug-induced liver injury

Drug-induced liver injury is a common cause of cholestatic liver disease. However, our patient was not taking any prescribed, over-the-counter, or herbal medications. Additionally, he denied heavy alcohol use.

Infiltrative disorders

Infiltrative disorders such as amyloidosis, sarcoidosis, or lymphoma should be considered in the differential diagnosis of cholestatic liver disease. A clue to a possible infiltrative process is a markedly elevated level of alkaline phosphatase with a mildly increased serum bilirubin concentration, both of which our patient had.

AFTER ULTRASONOGRAPHY, WHAT IS THE NEXT STEP?

2. Which of the following is the next most appropriate diagnostic test for our patient?

• Endoscopic retrograde cholangiopancreatography (ERCP)
• Magnetic resonance cholangiopancreatography (MRCP)
• Liver biopsy
• CT of the abdomen

Figure 1 shows a proposed algorithm for evaluating increased alkaline phosphatase levels.

If there is no biliary duct dilation on ultrasonography, then abnormal levels of alkaline phosphatase most likely represent an intrahepatic pattern of cholestatic liver injury. Therefore, additional imaging with CT or magnetic resonance imaging is of limited diagnostic value. ERCP is used today for therapy rather than diagnosis, so its use is limited to patients known to have dilated biliary ducts on imaging. Liver biopsy, however, can provide useful findings.

Case continued: He undergoes biopsy

Our patient underwent transjugular liver biopsy. During the procedure, transjugular venography showed stenosis in the right, middle, and left hepatic veins and the hepatic portion of the inferior vena cava, consistent with Budd-Chiari syndrome.

The liver biopsy specimen was positive for extensive deposition of slight eosinophilic and amorphous material in a sinusoidal pattern in the liver parenchyma, as well as in the portal tracts, with markedly atrophic hepatocytes. Congo red birefringence confirmed the diagnosis of amyloidosis. The immunohistochemical phenotype was positive for kappa light chains, which is diagnostic for primary-type amyloidosis, also called amyloidosis of light chain composition, or AL.

Bone marrow aspiration and bone marrow biopsy were performed and showed 22% plasma cells, well above the normal range (0–2%), consistent with the diagnosis of multiple myeloma.

BUDD-CHIARI SYNDROME: A CHALLENGING DIAGNOSIS

Budd-Chiari syndrome is a rare condition characterized by obstruction of venous outflow from the liver at a site that may vary from the small hepatic veins up to the inferior vena cava or even the right atrium.^5,6 Obstruction of hepatic venous outflow leads to sinusoidal congestion and hypoxic damage of the hepatocytes.⁷ Hypoxia and necrosis of the hepatocytes result in the release of free radicals. Cirrhosis can eventually occur secondary to ischemic necrosis of hepatocytes and hepatic fibrosis.⁸

The estimated incidence of this syndrome is 1 in 2.5 million persons per year.⁷ It is more prevalent in women and young adults.⁸

Heterogeneous in its causes and manifestations

Budd-Chiari syndrome is also heterogeneous in its manifestations, which depend on the extent of the occlusion, on the acuteness of the obstruction, and on whether venous collateral circulation has developed to decompress the liver sinusoids.^9,12,13 Therefore, on the basis of its clinical manifestations, it can be classified as fulminant, acute, subacute, or chronic.^12–16

The fulminant form presents with hepatic encephalopathy within 8 weeks after the development of jaundice. The subacute form, which is the most common, has a more insidious onset in which hepatic sinusoids are decompressed by portal and hepatic venous collateral circulation. The patient usually presents with abdominal pain, ascites, hepatomegaly, nausea, vomiting, and mild jaundice. Finally the chronic form presents as complications of cirrhosis.^12–16

Imaging plays an important role in diagnosing Budd-Chiari syndrome

Imaging plays an important role in detecting and classifying Budd-Chiari syndrome.

Duplex ultrasonography is useful for detecting this syndrome and has a sensitivity and specificity of 85%.⁹

CT and magnetic resonance imaging can also help in the diagnosis by showing thrombosis, obstruction, or occlusion in the hepatic vein or the inferior vena cava.⁵

Venography is the gold standard for diagnosis. However, it should be performed only if noninvasive tests are negative or nondiagnostic and there is a high clinical suspicion of this disease.¹⁷ Budd-Chiari syndrome has a characteristic pattern on venography known as “spider web,” which is due to the formation of venous collaterals to bypass the occluded hepatic veins.⁹

Liver biopsy is not necessarily required to confirm the diagnosis of Budd-Chiari syndrome, but it can help in diagnosing the acute or subacute forms and also in ruling out other causes. Histologic findings can include centrizonal congestion, loss of hepatocytes, hemorrhage, and fibrosis.^18,19 Regenerative nodules are found in about 25% of patients.¹⁹

TREATING BUDD-CHIARI SYNDROME

The primary goal of treatment is to prevent further extension of the venous thrombosis in the hepatic veins, in their collaterals, and in the intrahepatic and extrahepatic portal venous system. Resolution of hepatic congestion improves liver perfusion and preserves function of the hepatocytes.

Anticoagulation is recommended in the early stages. Heparin therapy should be initiated and subsequently switched to warfarin with the goal of achieving an international normalized ratio of the prothrombin time of 2.0 to 2.5.^8,9,19

Thrombolysis is effective in the acute form.^20,21 Recanalization, including percutaneous or transhepatic angioplasty of localized segments of the narrowed hepatic veins or inferior vena cava, has long-term patency rates of 80% to 90%.²²

If thrombolytic therapy and angioplasty are unsuccessful, a transjugular intrahepatic portosystemic shunt or a surgical procedure (side-to-side portocaval shunt, central splenorenal shunt, or mesocaval shunt) should be considered.⁹

Liver transplantation is another treatment option in those with fulminant Budd-Chiari syndrome or advanced liver cirrhosis.⁸

PROGNOSIS HAS IMPROVED

The prognosis of Budd-Chiari syndrome has improved, thanks to both earlier diagnosis and new treatments. The 1-year survival rate, which was about 60% before 1985, has increased to more than 80% in recent cohort studies.¹⁹

Studies have shown that the Child-Pugh score, which is based on a combination of serum albumin, bilirubin, prothrombin time, encephalopathy, and ascites, can be considered as an independent prognostic factor. A lower Child-Pugh score and a younger age are associated with a good prognosis.^19,23,24 (The Child-Pugh score cannot be applied to our patient because he does not have cirrhosis.)

What happened to our patient?

Our patient was started on anticoagulation for his Budd-Chiari syndrome and on bortezomib (Velcade) and dexamethasone for his multiple myeloma. He achieved remarkable improvement in his liver function tests. Follow-up duplex ultrasonography 1 month after discharge revealed that the stenosis in the hepatic veins had resolved. He is following up with the oncology clinic for management of his multiple myeloma.

A 25-year-old man presented to his primary care physician with generalized malaise. His symptoms started around 2 months earlier with progressive fatigue, nausea, decreased appetite, and weight loss (15 lb in 2 months). He denied having fever, chills, night sweats, abdominal pain, diarrhea, melena, or hematochezia.

His medical history was remarkable only for depression, well controlled with sertraline (Zoloft), which he started taking 3 years ago. He was not taking any other prescribed, over-the-counter, or herbal medications.

He had no family history of cancer or liver disease. He did not smoke and rarely drank alcohol. He had never used recreational drugs. He was sexually active with one female partner, used condoms for protection, and had never been diagnosed with a sexually transmitted disease. He had not traveled recently and had not been exposed to any pet.

The patient’s laboratory values on admission are shown in Table 1. Of note, his serum alkaline phosphatase level was 1,307 U/L (reference range 40–150 U/L).

LIVER TESTS CAN NARROW THE DIAGNOSIS

The most commonly used laboratory tests of the liver can be classified into those that measure either:

• Liver synthetic function (eg, the serum albumin and bilirubin concentrations and the prothrombin time) or
• Liver damage, as reflected by the serum concentrations of the enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, and gamma-glutamyltransferase (GGT).^1,2

ALT and AST are normally concentrated in the hepatocytes and thus, when present in the serum in elevated concentrations, are markers of liver cell injury. The serum levels of these enzymes start to increase within a few hours of liver cell injury as they leak out of the cells via the damaged cell membrane. AST is less liver-specific than ALT, since AST levels can be elevated not only in liver injury but also in muscle, cardiac, and red blood cell injury.^3,4

Alkaline phosphatase is actually a heterogeneous group of enzymes found mainly in liver and bone cells. Hepatic alkaline phosphatase is concentrated near the biliary canalicular membrane of the hepatocyte. Accordingly, increased levels of hepatic alkaline phosphatase are mainly seen in liver diseases that predominantly affect the biliary system.³

GGT is also concentrated in hepatic biliary epithelial cells, and thus GGT elevation is another marker of hepatobiliary disease. In fact, measuring the GGT level can help to determine whether an isolated elevation of alkaline phosphatase is due to liver injury.^2,3

Accordingly, liver diseases can be classified into two broad categories:

• Hepatocellular injury, in which the primary injury occurs to the hepatocytes
• Cholestatic injury, in which the primary injury is to the bile ducts.

In the former, elevated levels of ALT and AST predominate, while in the latter, elevated alkaline phosphatase is the main finding.³

WHAT TEST NEXT FOR OUR PATIENT?

1. What is the next most appropriate diagnostic step for our patient?

• Liver biopsy
• Ultrasonography of the liver
• Computed tomography (CT) of the liver
• Observation

Our patient has an elevated GGT level, which suggests that his elevated alkaline phosphatase is of hepatic rather than bony origin. Moreover, a serum alkaline phosphatase level that is elevated out of proportion to the aminotransferase levels reflects cholestatic liver injury.

CASE CONTINUED: ULTRASONOGRAPHY IS MOSTLY NORMAL

Ultrasonography of the right upper quadrant revealed that the liver had normal echogenicity and was mildly enlarged. There was no focal hepatic lesion. The gallbladder appeared normal, with no stones or sludge. No dilated intrahepatic or extrahepatic biliary ducts were seen. The common bile duct measured 4 mm. A small amount of ascites not amenable to paracentesis was present.

Thus, in the absence of biliary dilation on ultrasonography, we are dealing with an intrahepatic cholestatic process.

CAUSES OF CHOLESTATIC LIVER DISEASE

Viral hepatitis

Viral hepatitis most often produces a hepatocellular pattern of injury (ie, AST and ALT elevations predominate). However, in rare cases it can cause a cholestatic pattern of injury.

Our patient subsequently had serologic tests for viral hepatitis, including hepatitis A, B, and C, and the results were negative.

Autoimmune liver disease

The three most common forms of autoimmune liver disease are autoimmune hepatitis, primary biliary cirrhosis, and primary sclerosing cholangitis.

Autoimmune hepatitis is characterized by high serum ALT and AST levels, whereas primary biliary cirrhosis and primary sclerosing cholangitis are associated with predominant elevations of alkaline phosphatase, since they are cholestatic disorders.

Our patient’s alkaline phosphatase level was much higher than his ALT and AST levels, making the latter two diseases more likely.

Primary biliary cirrhosis (and autoimmune hepatitis) are associated with autoantibodies in the serum, such as antinuclear antibody, smooth muscle antibody, and antimitochondrial antibody.

Our patient subsequently was tested for these antibodies, and the results were negative.

Primary sclerosing cholangitis usually affects the extrahepatic biliary system. Thus, if it is present, abnormalities should be seen on imaging.

As mentioned previously, no dilated intrahepatic or extrahepatic biliary ducts were seen on ultrasonography in our patient. Moreover, primary sclerosing cholangitis is associated with inflammatory bowel disease, particularly ulcerative colitis, which our patient did not have.

Drug-induced liver injury

Drug-induced liver injury is a common cause of cholestatic liver disease. However, our patient was not taking any prescribed, over-the-counter, or herbal medications. Additionally, he denied heavy alcohol use.

Infiltrative disorders

Infiltrative disorders such as amyloidosis, sarcoidosis, or lymphoma should be considered in the differential diagnosis of cholestatic liver disease. A clue to a possible infiltrative process is a markedly elevated level of alkaline phosphatase with a mildly increased serum bilirubin concentration, both of which our patient had.

AFTER ULTRASONOGRAPHY, WHAT IS THE NEXT STEP?

2. Which of the following is the next most appropriate diagnostic test for our patient?

• Endoscopic retrograde cholangiopancreatography (ERCP)
• Magnetic resonance cholangiopancreatography (MRCP)
• Liver biopsy
• CT of the abdomen

Figure 1 shows a proposed algorithm for evaluating increased alkaline phosphatase levels.

If there is no biliary duct dilation on ultrasonography, then abnormal levels of alkaline phosphatase most likely represent an intrahepatic pattern of cholestatic liver injury. Therefore, additional imaging with CT or magnetic resonance imaging is of limited diagnostic value. ERCP is used today for therapy rather than diagnosis, so its use is limited to patients known to have dilated biliary ducts on imaging. Liver biopsy, however, can provide useful findings.

Case continued: He undergoes biopsy

Our patient underwent transjugular liver biopsy. During the procedure, transjugular venography showed stenosis in the right, middle, and left hepatic veins and the hepatic portion of the inferior vena cava, consistent with Budd-Chiari syndrome.

The liver biopsy specimen was positive for extensive deposition of slight eosinophilic and amorphous material in a sinusoidal pattern in the liver parenchyma, as well as in the portal tracts, with markedly atrophic hepatocytes. Congo red birefringence confirmed the diagnosis of amyloidosis. The immunohistochemical phenotype was positive for kappa light chains, which is diagnostic for primary-type amyloidosis, also called amyloidosis of light chain composition, or AL.

Bone marrow aspiration and bone marrow biopsy were performed and showed 22% plasma cells, well above the normal range (0–2%), consistent with the diagnosis of multiple myeloma.

BUDD-CHIARI SYNDROME: A CHALLENGING DIAGNOSIS

Budd-Chiari syndrome is a rare condition characterized by obstruction of venous outflow from the liver at a site that may vary from the small hepatic veins up to the inferior vena cava or even the right atrium.^5,6 Obstruction of hepatic venous outflow leads to sinusoidal congestion and hypoxic damage of the hepatocytes.⁷ Hypoxia and necrosis of the hepatocytes result in the release of free radicals. Cirrhosis can eventually occur secondary to ischemic necrosis of hepatocytes and hepatic fibrosis.⁸

The estimated incidence of this syndrome is 1 in 2.5 million persons per year.⁷ It is more prevalent in women and young adults.⁸

Heterogeneous in its causes and manifestations

Budd-Chiari syndrome is also heterogeneous in its manifestations, which depend on the extent of the occlusion, on the acuteness of the obstruction, and on whether venous collateral circulation has developed to decompress the liver sinusoids.^9,12,13 Therefore, on the basis of its clinical manifestations, it can be classified as fulminant, acute, subacute, or chronic.^12–16

The fulminant form presents with hepatic encephalopathy within 8 weeks after the development of jaundice. The subacute form, which is the most common, has a more insidious onset in which hepatic sinusoids are decompressed by portal and hepatic venous collateral circulation. The patient usually presents with abdominal pain, ascites, hepatomegaly, nausea, vomiting, and mild jaundice. Finally the chronic form presents as complications of cirrhosis.^12–16

Imaging plays an important role in diagnosing Budd-Chiari syndrome

Imaging plays an important role in detecting and classifying Budd-Chiari syndrome.

Duplex ultrasonography is useful for detecting this syndrome and has a sensitivity and specificity of 85%.⁹

CT and magnetic resonance imaging can also help in the diagnosis by showing thrombosis, obstruction, or occlusion in the hepatic vein or the inferior vena cava.⁵

Venography is the gold standard for diagnosis. However, it should be performed only if noninvasive tests are negative or nondiagnostic and there is a high clinical suspicion of this disease.¹⁷ Budd-Chiari syndrome has a characteristic pattern on venography known as “spider web,” which is due to the formation of venous collaterals to bypass the occluded hepatic veins.⁹

Liver biopsy is not necessarily required to confirm the diagnosis of Budd-Chiari syndrome, but it can help in diagnosing the acute or subacute forms and also in ruling out other causes. Histologic findings can include centrizonal congestion, loss of hepatocytes, hemorrhage, and fibrosis.^18,19 Regenerative nodules are found in about 25% of patients.¹⁹

TREATING BUDD-CHIARI SYNDROME

The primary goal of treatment is to prevent further extension of the venous thrombosis in the hepatic veins, in their collaterals, and in the intrahepatic and extrahepatic portal venous system. Resolution of hepatic congestion improves liver perfusion and preserves function of the hepatocytes.

Anticoagulation is recommended in the early stages. Heparin therapy should be initiated and subsequently switched to warfarin with the goal of achieving an international normalized ratio of the prothrombin time of 2.0 to 2.5.^8,9,19

Thrombolysis is effective in the acute form.^20,21 Recanalization, including percutaneous or transhepatic angioplasty of localized segments of the narrowed hepatic veins or inferior vena cava, has long-term patency rates of 80% to 90%.²²

If thrombolytic therapy and angioplasty are unsuccessful, a transjugular intrahepatic portosystemic shunt or a surgical procedure (side-to-side portocaval shunt, central splenorenal shunt, or mesocaval shunt) should be considered.⁹

Liver transplantation is another treatment option in those with fulminant Budd-Chiari syndrome or advanced liver cirrhosis.⁸

PROGNOSIS HAS IMPROVED

The prognosis of Budd-Chiari syndrome has improved, thanks to both earlier diagnosis and new treatments. The 1-year survival rate, which was about 60% before 1985, has increased to more than 80% in recent cohort studies.¹⁹

Studies have shown that the Child-Pugh score, which is based on a combination of serum albumin, bilirubin, prothrombin time, encephalopathy, and ascites, can be considered as an independent prognostic factor. A lower Child-Pugh score and a younger age are associated with a good prognosis.^19,23,24 (The Child-Pugh score cannot be applied to our patient because he does not have cirrhosis.)

What happened to our patient?

Our patient was started on anticoagulation for his Budd-Chiari syndrome and on bortezomib (Velcade) and dexamethasone for his multiple myeloma. He achieved remarkable improvement in his liver function tests. Follow-up duplex ultrasonography 1 month after discharge revealed that the stenosis in the hepatic veins had resolved. He is following up with the oncology clinic for management of his multiple myeloma.