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Study finds no link between platelet count, surgery bleed risk in cirrhosis
The findings raise questions about current recommendations that call for transfusing platelet concentrates to reduce bleeding risk during surgery in cirrhosis patients with extremely low platelet counts, Gian Marco Podda, MD, PhD, said at the International Society on Thrombosis and Haemostasis virtual congress.
The overall rate of perioperative bleeding was 8.9% in 996 patients who underwent excision of hepatocellular carcinoma by resection (42%) or radiofrequency ablation (58%) without platelet transfusion between 1998 and 2018. The rates were slightly higher among 65 patients with platelet count of fewer than 50 × 109/L indicating severe thrombocytopenia, and in 292 patients with counts of 50-100 × 109/L, indicating moderate thrombocytopenia (10.8% and 10.2%, respectively), compared with those with a platelet count of higher than 100 × 109/L (8.1%), but the differences were not statistically significant, said Dr. Podda of the University of Milan (Italy).
The corresponding rates among those who underwent radiofrequency ablation were 8.6%, 5.9%, and 5%, and among those who underwent resection, they were 18.8%, 17.7%, and 15.9%.
On multivariate analysis, factors associated with an increased incidence of major bleeding were low hemoglobin level (odds ratio, 0.57), age over 65 years (OR, 1.19), aspartate aminotransferase level greater than twice the upper limit of normal (OR, 2.12), hepatitis B or C cirrhosis versus cryptogenic cirrhosis (OR, 0.08), and resection versus radiofrequency ablation (OR, 3.74), he noted. Logistic regression analysis showed no significant association between platelet count and major bleeding events.
Mortality, a secondary outcome measure, was significantly higher among those with moderate or severe thrombocytopenia (rate of 5.5% for each), compared with those with mild or no thrombocytopenia (2.4%), Dr. Podda said.
Factors associated with mortality on multivariate analysis were severe liver dysfunction as demonstrated by Model for End-Stage Liver Disease score of 10 or greater versus less than 10 (OR, 3.13) and Child-Pugh B and C score versus Child-Pugh A score (OR, 16.72), advanced tumor status as measured by Barcelona-Clínic Liver Cancer staging greater than A4 versus A1 (OR, 5.78), major bleeding (OR, 4.59), and resection versus radiofrequency ablation (OR, 3.31).
“Low platelet count was associated with an increased risk of mortality at 3 months. However, this association disappeared at the multivariate analysis, which took into account markers of severity of liver cirrhosis,” he said.
Dr. Podda and his colleagues conducted the study in light of a recommendation from a consensus conference of the Italian Association for the Study of Liver Disease and the Italian Society of Internal Medicine that called for increasing platelet count by platelet transfusions in patients with cirrhosis who undergo an invasive procedure and who have a platelet count lower than 50 × 109/L.
“This recommendation mostly stemmed from consideration of biological plausibility prospects rather than being based on hard experimental evidence,” he explained, noting that such severe thrombocytopenia affects about 10% of patients with liver cirrhosis.
Based on the findings of this study, the practice is not supported, he concluded.
Dr. Podda reported honoraria from Sanofi, Boehringer Ingelheim.
SOURCE: Ronca V et al. ISTH 2020, Abstract OC 13.4.
The findings raise questions about current recommendations that call for transfusing platelet concentrates to reduce bleeding risk during surgery in cirrhosis patients with extremely low platelet counts, Gian Marco Podda, MD, PhD, said at the International Society on Thrombosis and Haemostasis virtual congress.
The overall rate of perioperative bleeding was 8.9% in 996 patients who underwent excision of hepatocellular carcinoma by resection (42%) or radiofrequency ablation (58%) without platelet transfusion between 1998 and 2018. The rates were slightly higher among 65 patients with platelet count of fewer than 50 × 109/L indicating severe thrombocytopenia, and in 292 patients with counts of 50-100 × 109/L, indicating moderate thrombocytopenia (10.8% and 10.2%, respectively), compared with those with a platelet count of higher than 100 × 109/L (8.1%), but the differences were not statistically significant, said Dr. Podda of the University of Milan (Italy).
The corresponding rates among those who underwent radiofrequency ablation were 8.6%, 5.9%, and 5%, and among those who underwent resection, they were 18.8%, 17.7%, and 15.9%.
On multivariate analysis, factors associated with an increased incidence of major bleeding were low hemoglobin level (odds ratio, 0.57), age over 65 years (OR, 1.19), aspartate aminotransferase level greater than twice the upper limit of normal (OR, 2.12), hepatitis B or C cirrhosis versus cryptogenic cirrhosis (OR, 0.08), and resection versus radiofrequency ablation (OR, 3.74), he noted. Logistic regression analysis showed no significant association between platelet count and major bleeding events.
Mortality, a secondary outcome measure, was significantly higher among those with moderate or severe thrombocytopenia (rate of 5.5% for each), compared with those with mild or no thrombocytopenia (2.4%), Dr. Podda said.
Factors associated with mortality on multivariate analysis were severe liver dysfunction as demonstrated by Model for End-Stage Liver Disease score of 10 or greater versus less than 10 (OR, 3.13) and Child-Pugh B and C score versus Child-Pugh A score (OR, 16.72), advanced tumor status as measured by Barcelona-Clínic Liver Cancer staging greater than A4 versus A1 (OR, 5.78), major bleeding (OR, 4.59), and resection versus radiofrequency ablation (OR, 3.31).
“Low platelet count was associated with an increased risk of mortality at 3 months. However, this association disappeared at the multivariate analysis, which took into account markers of severity of liver cirrhosis,” he said.
Dr. Podda and his colleagues conducted the study in light of a recommendation from a consensus conference of the Italian Association for the Study of Liver Disease and the Italian Society of Internal Medicine that called for increasing platelet count by platelet transfusions in patients with cirrhosis who undergo an invasive procedure and who have a platelet count lower than 50 × 109/L.
“This recommendation mostly stemmed from consideration of biological plausibility prospects rather than being based on hard experimental evidence,” he explained, noting that such severe thrombocytopenia affects about 10% of patients with liver cirrhosis.
Based on the findings of this study, the practice is not supported, he concluded.
Dr. Podda reported honoraria from Sanofi, Boehringer Ingelheim.
SOURCE: Ronca V et al. ISTH 2020, Abstract OC 13.4.
The findings raise questions about current recommendations that call for transfusing platelet concentrates to reduce bleeding risk during surgery in cirrhosis patients with extremely low platelet counts, Gian Marco Podda, MD, PhD, said at the International Society on Thrombosis and Haemostasis virtual congress.
The overall rate of perioperative bleeding was 8.9% in 996 patients who underwent excision of hepatocellular carcinoma by resection (42%) or radiofrequency ablation (58%) without platelet transfusion between 1998 and 2018. The rates were slightly higher among 65 patients with platelet count of fewer than 50 × 109/L indicating severe thrombocytopenia, and in 292 patients with counts of 50-100 × 109/L, indicating moderate thrombocytopenia (10.8% and 10.2%, respectively), compared with those with a platelet count of higher than 100 × 109/L (8.1%), but the differences were not statistically significant, said Dr. Podda of the University of Milan (Italy).
The corresponding rates among those who underwent radiofrequency ablation were 8.6%, 5.9%, and 5%, and among those who underwent resection, they were 18.8%, 17.7%, and 15.9%.
On multivariate analysis, factors associated with an increased incidence of major bleeding were low hemoglobin level (odds ratio, 0.57), age over 65 years (OR, 1.19), aspartate aminotransferase level greater than twice the upper limit of normal (OR, 2.12), hepatitis B or C cirrhosis versus cryptogenic cirrhosis (OR, 0.08), and resection versus radiofrequency ablation (OR, 3.74), he noted. Logistic regression analysis showed no significant association between platelet count and major bleeding events.
Mortality, a secondary outcome measure, was significantly higher among those with moderate or severe thrombocytopenia (rate of 5.5% for each), compared with those with mild or no thrombocytopenia (2.4%), Dr. Podda said.
Factors associated with mortality on multivariate analysis were severe liver dysfunction as demonstrated by Model for End-Stage Liver Disease score of 10 or greater versus less than 10 (OR, 3.13) and Child-Pugh B and C score versus Child-Pugh A score (OR, 16.72), advanced tumor status as measured by Barcelona-Clínic Liver Cancer staging greater than A4 versus A1 (OR, 5.78), major bleeding (OR, 4.59), and resection versus radiofrequency ablation (OR, 3.31).
“Low platelet count was associated with an increased risk of mortality at 3 months. However, this association disappeared at the multivariate analysis, which took into account markers of severity of liver cirrhosis,” he said.
Dr. Podda and his colleagues conducted the study in light of a recommendation from a consensus conference of the Italian Association for the Study of Liver Disease and the Italian Society of Internal Medicine that called for increasing platelet count by platelet transfusions in patients with cirrhosis who undergo an invasive procedure and who have a platelet count lower than 50 × 109/L.
“This recommendation mostly stemmed from consideration of biological plausibility prospects rather than being based on hard experimental evidence,” he explained, noting that such severe thrombocytopenia affects about 10% of patients with liver cirrhosis.
Based on the findings of this study, the practice is not supported, he concluded.
Dr. Podda reported honoraria from Sanofi, Boehringer Ingelheim.
SOURCE: Ronca V et al. ISTH 2020, Abstract OC 13.4.
REPORTING FROM THE 2020 ISTH CONGRESS
Large cohort study: Bevacizumab safe, effective for severe HHT bleeds
Systemic bevacizumab is safe and highly effective for the management of chronic bleeding and anemia in patients with hereditary hemorrhagic telangiectasia (HHT), according to findings from an international observational study.
In 238 patients from 12 international centers who were treated with bevacizumab for a median of 12 months, mean hemoglobin levels increased by 3.2 g/dL (mean pre- and posttreatment levels, 8.6 vs. 11.8 g/dL), and epistaxis severity scores (ESS) decreased by a mean of 3.4 points (pre- and posttreatment scores, 6.8 vs. 3.4 points), Hanny Al-Samkari, MD, reported at the International Society on Thrombosis and Haemostasis virtual congress.
As established in prior studies, the minimal clinically important difference in the ESS, a well-validated 10-point bleeding score in HHT, is 0.71 points; the mean reduction seen in this study was 4.75 times that, noted Dr. Al-Samkari, a clinical investigator and hematologist at Massachusetts General Hospital, Boston.
Further, the median number of red blood cell units transfused during the first year of treatment decreased by 82%, compared with the 6 months prior to treatment (9.0 vs. 0 units), and median iron infusions decreased by 70% during the same period (8.0 vs. 2.0 infusions), he said, adding that these improvements occurred within the first 6 months of treatment and were maintained through 12 months.
Study subjects were adults with a mean age of 63 years who were treated with systemic bevacizumab, a vascular endothelial growth factor receptor (VEGF) monoclonal antibody, between 2011 and 2019 for the primary indication of moderate to severe chronic HHT-related bleeding and anemia. Treatment involved four to eight induction infusions – typically at a dose of 5 mg/kg and given 4 weeks apart – followed by bevacizumab maintenance, either as continuous or scheduled maintenance at 4-, 8-, or 12-week intervals regardless of symptoms, or on an as-needed basis, with 2-6 infusions for signs or symptoms of rebleeding.
Patients received a median of 11 infusions, and 181 received maintenance treatment, including continuous or scheduled maintenance in 136 patients and as-needed maintenance in 45 patients, Dr. Al-Samkari said.
The treatment was generally well tolerated; the most common adverse events during 344 patient-years of treatment were hypertension, fatigue, and proteinuria. No fatal treatment-related adverse events occurred, and no increase in adverse events occurred with longer treatment, he noted
Venous thromboembolism occurred in five patients, including two patients who had “provoked events immediately following joint replacement surgery,” he said.
Thirteen patients (5%) discontinued treatment – 11 for inadequate effect and 2 for side effects, he noted.
Subgroup analyses showed that outcomes were similar regardless of underlying pathogenic mutation, but among those receiving bevacizumab maintenance, the continuous approach, compared with as-needed maintenance, was associated with greater improvement in hemoglobin (10.8 vs. 12.3 g/dL) and ESS (mean, 4.96 vs. 2.88) during months 7-12 of treatment, “which is the time most reflective of the effect of maintenance,” he said.
HHT, also known as Osler-Weber-Rendu disease, is a “rare, genetic, progressive, multisystem bleeding disorder resulting from disorder of angiogenesis,” Dr. Al-Samkari explained, adding that the condition is characterized by severe, recurrent epistaxis and chronic gastrointestinal bleeding.
“Bleeding frequently leads to iron deficiency anemia, which may be severe and dependent on regular iron infusions and/or blood transfusions,” he said.
Though rare, it is the second most common bleeding disorder worldwide, with a prevalence about twice that of hemophilia A and six times that of hemophilia B.
“Despite this, it has no FDA-approved therapies,” he said. “The current mainstay of care is surgical or procedural local hemostatic intervention – which is usually temporizing – and hematological support in the form of blood and iron.”
However, given that the underlying genetic defects that cause HHT result in elevations in VEGF, targeting VEGF with existing antiangiogenic agents is a promising approach.
In fact, several centers have been using bevacizumab for several years as an off-label treatment for bleeding in this setting, and while scattered case reports and small case series suggest efficacy, no “large or definitive studies” have been conducted, and safety hasn’t been carefully evaluated, he said.
To that end, the International Hereditary Hemorrhagic Telangiectasia Intravenous Bevacizumab Investigative Team (InHIBIT) was formed. The current report, “the largest study of antiangiogenic therapy to date in HHT,” represents the results of the InHIBIT-Bleed study, the first completed by the team. The next study will address bevacizumab for the treatment of high-output cardiac failure in HHT (the InHIBIT-HF study), Dr. Al-Samkari said.
Though limited by its retrospective nature and lack of a unified treatment protocol, the InHIBIT-Bleed study provides important information and is strengthened by the large cohort size, especially given that HHT is a rare disease, and by other factors, such as the substantial number of patient-years of treatment.
“Bevacizumab was effective in the management of severe HHT-related epistaxis and GI bleeds,” he said, noting the “significant and striking improvements” on a variety of measures.
Questioned about the durability of treatment effects after treatment discontinuation, Dr. Al-Samkari said outcomes are variable, “highly patient dependent,” and “something that we really need to investigate thoroughly.”
As for the potential for anti-VEGF therapy for bleeding in certain non-HHT settings, session moderator Michael Makris, MD, professor of haemostasis and thrombosis at the University of Sheffield, England, said the possibilities are intriguing.
“I work with lots of patients with von Willebrand disease and angiodysplasia,” he said, adding that angiodysplasia-related bleeding in type 2A von Willebrand disease is a major issue.
Dr. Al-Samkari agreed that the possibility is worth exploring.
“We have looked at this in a small number of patients, and the jury is still out,” he said. “But there is a publication in Gastroenterology – Albitar et al. – that evaluated bevacizumab in patients without HHT [who had] angiodysplasias from other causes – not specifically in type 2 von Willebrand syndrome ... and did find that it was effective at causing the angiodysplasias to regress, hemoglobin to improve.
“So the non-HHT use of this agent is certainly an important one [and] we do have retrospective evidence in a small group of patients who don’t have HHT, who do have angiodysplasias and bleeding, that it may be effective as well.”
Dr. Al-Samkari reported receiving research support and/or consulting fees from Agios, Amgen, and Dova.
SOURCE: Al-Samkari H et al. ISTH 2020, Abstract OC 09.2.
Systemic bevacizumab is safe and highly effective for the management of chronic bleeding and anemia in patients with hereditary hemorrhagic telangiectasia (HHT), according to findings from an international observational study.
In 238 patients from 12 international centers who were treated with bevacizumab for a median of 12 months, mean hemoglobin levels increased by 3.2 g/dL (mean pre- and posttreatment levels, 8.6 vs. 11.8 g/dL), and epistaxis severity scores (ESS) decreased by a mean of 3.4 points (pre- and posttreatment scores, 6.8 vs. 3.4 points), Hanny Al-Samkari, MD, reported at the International Society on Thrombosis and Haemostasis virtual congress.
As established in prior studies, the minimal clinically important difference in the ESS, a well-validated 10-point bleeding score in HHT, is 0.71 points; the mean reduction seen in this study was 4.75 times that, noted Dr. Al-Samkari, a clinical investigator and hematologist at Massachusetts General Hospital, Boston.
Further, the median number of red blood cell units transfused during the first year of treatment decreased by 82%, compared with the 6 months prior to treatment (9.0 vs. 0 units), and median iron infusions decreased by 70% during the same period (8.0 vs. 2.0 infusions), he said, adding that these improvements occurred within the first 6 months of treatment and were maintained through 12 months.
Study subjects were adults with a mean age of 63 years who were treated with systemic bevacizumab, a vascular endothelial growth factor receptor (VEGF) monoclonal antibody, between 2011 and 2019 for the primary indication of moderate to severe chronic HHT-related bleeding and anemia. Treatment involved four to eight induction infusions – typically at a dose of 5 mg/kg and given 4 weeks apart – followed by bevacizumab maintenance, either as continuous or scheduled maintenance at 4-, 8-, or 12-week intervals regardless of symptoms, or on an as-needed basis, with 2-6 infusions for signs or symptoms of rebleeding.
Patients received a median of 11 infusions, and 181 received maintenance treatment, including continuous or scheduled maintenance in 136 patients and as-needed maintenance in 45 patients, Dr. Al-Samkari said.
The treatment was generally well tolerated; the most common adverse events during 344 patient-years of treatment were hypertension, fatigue, and proteinuria. No fatal treatment-related adverse events occurred, and no increase in adverse events occurred with longer treatment, he noted
Venous thromboembolism occurred in five patients, including two patients who had “provoked events immediately following joint replacement surgery,” he said.
Thirteen patients (5%) discontinued treatment – 11 for inadequate effect and 2 for side effects, he noted.
Subgroup analyses showed that outcomes were similar regardless of underlying pathogenic mutation, but among those receiving bevacizumab maintenance, the continuous approach, compared with as-needed maintenance, was associated with greater improvement in hemoglobin (10.8 vs. 12.3 g/dL) and ESS (mean, 4.96 vs. 2.88) during months 7-12 of treatment, “which is the time most reflective of the effect of maintenance,” he said.
HHT, also known as Osler-Weber-Rendu disease, is a “rare, genetic, progressive, multisystem bleeding disorder resulting from disorder of angiogenesis,” Dr. Al-Samkari explained, adding that the condition is characterized by severe, recurrent epistaxis and chronic gastrointestinal bleeding.
“Bleeding frequently leads to iron deficiency anemia, which may be severe and dependent on regular iron infusions and/or blood transfusions,” he said.
Though rare, it is the second most common bleeding disorder worldwide, with a prevalence about twice that of hemophilia A and six times that of hemophilia B.
“Despite this, it has no FDA-approved therapies,” he said. “The current mainstay of care is surgical or procedural local hemostatic intervention – which is usually temporizing – and hematological support in the form of blood and iron.”
However, given that the underlying genetic defects that cause HHT result in elevations in VEGF, targeting VEGF with existing antiangiogenic agents is a promising approach.
In fact, several centers have been using bevacizumab for several years as an off-label treatment for bleeding in this setting, and while scattered case reports and small case series suggest efficacy, no “large or definitive studies” have been conducted, and safety hasn’t been carefully evaluated, he said.
To that end, the International Hereditary Hemorrhagic Telangiectasia Intravenous Bevacizumab Investigative Team (InHIBIT) was formed. The current report, “the largest study of antiangiogenic therapy to date in HHT,” represents the results of the InHIBIT-Bleed study, the first completed by the team. The next study will address bevacizumab for the treatment of high-output cardiac failure in HHT (the InHIBIT-HF study), Dr. Al-Samkari said.
Though limited by its retrospective nature and lack of a unified treatment protocol, the InHIBIT-Bleed study provides important information and is strengthened by the large cohort size, especially given that HHT is a rare disease, and by other factors, such as the substantial number of patient-years of treatment.
“Bevacizumab was effective in the management of severe HHT-related epistaxis and GI bleeds,” he said, noting the “significant and striking improvements” on a variety of measures.
Questioned about the durability of treatment effects after treatment discontinuation, Dr. Al-Samkari said outcomes are variable, “highly patient dependent,” and “something that we really need to investigate thoroughly.”
As for the potential for anti-VEGF therapy for bleeding in certain non-HHT settings, session moderator Michael Makris, MD, professor of haemostasis and thrombosis at the University of Sheffield, England, said the possibilities are intriguing.
“I work with lots of patients with von Willebrand disease and angiodysplasia,” he said, adding that angiodysplasia-related bleeding in type 2A von Willebrand disease is a major issue.
Dr. Al-Samkari agreed that the possibility is worth exploring.
“We have looked at this in a small number of patients, and the jury is still out,” he said. “But there is a publication in Gastroenterology – Albitar et al. – that evaluated bevacizumab in patients without HHT [who had] angiodysplasias from other causes – not specifically in type 2 von Willebrand syndrome ... and did find that it was effective at causing the angiodysplasias to regress, hemoglobin to improve.
“So the non-HHT use of this agent is certainly an important one [and] we do have retrospective evidence in a small group of patients who don’t have HHT, who do have angiodysplasias and bleeding, that it may be effective as well.”
Dr. Al-Samkari reported receiving research support and/or consulting fees from Agios, Amgen, and Dova.
SOURCE: Al-Samkari H et al. ISTH 2020, Abstract OC 09.2.
Systemic bevacizumab is safe and highly effective for the management of chronic bleeding and anemia in patients with hereditary hemorrhagic telangiectasia (HHT), according to findings from an international observational study.
In 238 patients from 12 international centers who were treated with bevacizumab for a median of 12 months, mean hemoglobin levels increased by 3.2 g/dL (mean pre- and posttreatment levels, 8.6 vs. 11.8 g/dL), and epistaxis severity scores (ESS) decreased by a mean of 3.4 points (pre- and posttreatment scores, 6.8 vs. 3.4 points), Hanny Al-Samkari, MD, reported at the International Society on Thrombosis and Haemostasis virtual congress.
As established in prior studies, the minimal clinically important difference in the ESS, a well-validated 10-point bleeding score in HHT, is 0.71 points; the mean reduction seen in this study was 4.75 times that, noted Dr. Al-Samkari, a clinical investigator and hematologist at Massachusetts General Hospital, Boston.
Further, the median number of red blood cell units transfused during the first year of treatment decreased by 82%, compared with the 6 months prior to treatment (9.0 vs. 0 units), and median iron infusions decreased by 70% during the same period (8.0 vs. 2.0 infusions), he said, adding that these improvements occurred within the first 6 months of treatment and were maintained through 12 months.
Study subjects were adults with a mean age of 63 years who were treated with systemic bevacizumab, a vascular endothelial growth factor receptor (VEGF) monoclonal antibody, between 2011 and 2019 for the primary indication of moderate to severe chronic HHT-related bleeding and anemia. Treatment involved four to eight induction infusions – typically at a dose of 5 mg/kg and given 4 weeks apart – followed by bevacizumab maintenance, either as continuous or scheduled maintenance at 4-, 8-, or 12-week intervals regardless of symptoms, or on an as-needed basis, with 2-6 infusions for signs or symptoms of rebleeding.
Patients received a median of 11 infusions, and 181 received maintenance treatment, including continuous or scheduled maintenance in 136 patients and as-needed maintenance in 45 patients, Dr. Al-Samkari said.
The treatment was generally well tolerated; the most common adverse events during 344 patient-years of treatment were hypertension, fatigue, and proteinuria. No fatal treatment-related adverse events occurred, and no increase in adverse events occurred with longer treatment, he noted
Venous thromboembolism occurred in five patients, including two patients who had “provoked events immediately following joint replacement surgery,” he said.
Thirteen patients (5%) discontinued treatment – 11 for inadequate effect and 2 for side effects, he noted.
Subgroup analyses showed that outcomes were similar regardless of underlying pathogenic mutation, but among those receiving bevacizumab maintenance, the continuous approach, compared with as-needed maintenance, was associated with greater improvement in hemoglobin (10.8 vs. 12.3 g/dL) and ESS (mean, 4.96 vs. 2.88) during months 7-12 of treatment, “which is the time most reflective of the effect of maintenance,” he said.
HHT, also known as Osler-Weber-Rendu disease, is a “rare, genetic, progressive, multisystem bleeding disorder resulting from disorder of angiogenesis,” Dr. Al-Samkari explained, adding that the condition is characterized by severe, recurrent epistaxis and chronic gastrointestinal bleeding.
“Bleeding frequently leads to iron deficiency anemia, which may be severe and dependent on regular iron infusions and/or blood transfusions,” he said.
Though rare, it is the second most common bleeding disorder worldwide, with a prevalence about twice that of hemophilia A and six times that of hemophilia B.
“Despite this, it has no FDA-approved therapies,” he said. “The current mainstay of care is surgical or procedural local hemostatic intervention – which is usually temporizing – and hematological support in the form of blood and iron.”
However, given that the underlying genetic defects that cause HHT result in elevations in VEGF, targeting VEGF with existing antiangiogenic agents is a promising approach.
In fact, several centers have been using bevacizumab for several years as an off-label treatment for bleeding in this setting, and while scattered case reports and small case series suggest efficacy, no “large or definitive studies” have been conducted, and safety hasn’t been carefully evaluated, he said.
To that end, the International Hereditary Hemorrhagic Telangiectasia Intravenous Bevacizumab Investigative Team (InHIBIT) was formed. The current report, “the largest study of antiangiogenic therapy to date in HHT,” represents the results of the InHIBIT-Bleed study, the first completed by the team. The next study will address bevacizumab for the treatment of high-output cardiac failure in HHT (the InHIBIT-HF study), Dr. Al-Samkari said.
Though limited by its retrospective nature and lack of a unified treatment protocol, the InHIBIT-Bleed study provides important information and is strengthened by the large cohort size, especially given that HHT is a rare disease, and by other factors, such as the substantial number of patient-years of treatment.
“Bevacizumab was effective in the management of severe HHT-related epistaxis and GI bleeds,” he said, noting the “significant and striking improvements” on a variety of measures.
Questioned about the durability of treatment effects after treatment discontinuation, Dr. Al-Samkari said outcomes are variable, “highly patient dependent,” and “something that we really need to investigate thoroughly.”
As for the potential for anti-VEGF therapy for bleeding in certain non-HHT settings, session moderator Michael Makris, MD, professor of haemostasis and thrombosis at the University of Sheffield, England, said the possibilities are intriguing.
“I work with lots of patients with von Willebrand disease and angiodysplasia,” he said, adding that angiodysplasia-related bleeding in type 2A von Willebrand disease is a major issue.
Dr. Al-Samkari agreed that the possibility is worth exploring.
“We have looked at this in a small number of patients, and the jury is still out,” he said. “But there is a publication in Gastroenterology – Albitar et al. – that evaluated bevacizumab in patients without HHT [who had] angiodysplasias from other causes – not specifically in type 2 von Willebrand syndrome ... and did find that it was effective at causing the angiodysplasias to regress, hemoglobin to improve.
“So the non-HHT use of this agent is certainly an important one [and] we do have retrospective evidence in a small group of patients who don’t have HHT, who do have angiodysplasias and bleeding, that it may be effective as well.”
Dr. Al-Samkari reported receiving research support and/or consulting fees from Agios, Amgen, and Dova.
SOURCE: Al-Samkari H et al. ISTH 2020, Abstract OC 09.2.
FROM THE 2020 ISTH CONGRESS
SPK-8011 AAV-mediated hemophilia A therapy shows stability, durability
SPK-8011, an investigational adeno-associated virus (AAV)–mediated gene therapy for hemophilia A, provides stable and durable factor VIII expression with no major safety concerns, according to findings at least 2 years after a single treatment in patients from a phase 1/2 trial.
The first 5 of 14 adult men with hemophilia A and who had factor VIII (FVIII) activity of 2% or less before treatment with SPK-8011 (at single doses of either 5 × 1011 or 1 × 1012 vg/kg), showed no development of FVIII inhibitors or evidence of FVIII cellular immune response at 106-142 weeks’ follow-up after vector infusion, according to Lindsey A. George, MD, at the International Society of Thrombosis and Haemostasis 2020 virtual congress.
At follow-up, the two who had received a 5 × 1011 vg/kg dose had FVIII activity of 6.9%-8.4%, and the three in the 1 × 1012 vg/kg cohort had FVIII activity of 5.2%-19.8%, said Dr. George, of the Children’s Hospital of Philadelphia.
Overall, 12 of the 14 patients in the study had sustained FVIII expression, including 7 of 9 who received the highest SPK-8011 dose of 2 × 1012 vg/kg. In the 12 with sustained expression, a “remarkable” 91% reduction in the annualized bleeding rate from the year prior to vs. the year after vector infusion was observed, she said.
“Similarly, looking at number of factor infusions before vector infusion relative to the number of factor infusions after vector infusion ... [there was] evidence of remarkable preliminary efficacy,” she added, noting a 96% reduction in factor consumption.
The findings are of note because, while clinical studies of Spark Therapeutic’s SPK-8011 product in hemophilia B and preclinical models in hemophilia A showed promising reductions in bleeds and stable, durable levels of FVIII expression after therapy, the first successful clinical trial of an AAV-mediated gene therapy in hemophilia A – the BioMarin AAV serotype 5 human FVIII-SQ (valoctocogene roxaparvovec) – showed an unexpected decline in FVIII expression at 1, 2, 3, and 4 years.
“This may be particularly relevant in the context of development of multi-serotype AAV neutralizing antibodies (NAb) following AAV vector administration,” Dr. George said, referencing a small study in which she and her colleagues showed long-term persistence of cross-reactive AAV NAb. The findings of that study, which is currently in press in Molecular Therapy, “suggest that repeat AAV vector infusion is unlikely to be possible with current methods.”
Initial results from the SPK-8011 study were presented at the 2018 American Society of Hematology annual meeting. No major safety issues have emerged since those data were presented at ASH; no deaths have occurred, and none of the patients developed FVIII inhibitors.
Treatment-related adverse events were limited to an infusion reaction in one patient, which resolved completely, and liver enzyme elevations in three patients, which also resolved. One serious adverse event – a grade 2 transaminitis that resulted in elective hospitalization for intravenous steroid administration, also resolved.
With respect to vector clearance, there was “no evidence of vector in either saliva, semen, serum, urine, or peripheral blood mononuclear cells by 6 weeks after vector infusion,” Dr. George said.
One-stage assay determination of FVIII activity showed that activity greater than 10% permits an absolute bleeding rate (ABR) of less than 1%, which is consistent with hemophilia natural history studies. Therefore “these data support that FVIII activity that is approximately greater than 10% “may be adequate to either eliminate or achieve an ABR of less than 1,” she said.
“With respect to assay discrepancy, our data at least preliminarily support that the one-stage assay determinant of hepatocyte-derived FVIII correlates with clinical phenotype,” she added.
The findings in the first five patients demonstrate preliminary stability of FVIII expression at follow up between 2 and 3.3 years, she said.
Further, of the nine patients who received the 2 × 1012 vg/kg dose, seven had sustained FVIII expression at about 1.5 years, five of the seven had no bleeds, and two lost FVIII expression and returned to prophylaxis uneventfully, she noted.
“The future directions of this work are ultimately to explore the optimal vector dose and immunosuppression regimens to achieve predictable, safe, efficacious, and durable FVIII expression,” she said.
Asked during a question and answer period about potential reasons for the differences in durability seen with SBK-8011 versus valoctocogene roxaparvovec, Dr. George said they remain unclear but could be related to differences in vector doses and manufacturing platforms.
Emerging data may allow for better comparisons, she added.
Session moderator Sebastien Lacroix-Desmazes, MD, of Centre de Recherche des Cordeliers, Paris, further asked about plans to optimize the immunosuppression regimen.
Plans are indeed in the works to identify the optimal immunosuppression regimen and to optimize immunosuppression in this trial, Dr. George said, noting that Spark Therapeutics “has outlined a plan to further investigate this in phase 1/2 trial before progressing into phase 3 study.”
Spark Therapeutic sponsored the SPK-8011 study. Dr. George disclosed consulting and/or data safety monitoring board activity for Pfizer and AvroBio.
SOURCE: George L et al. 2020 ISTH Congress, Abstract OC 03.5.
SPK-8011, an investigational adeno-associated virus (AAV)–mediated gene therapy for hemophilia A, provides stable and durable factor VIII expression with no major safety concerns, according to findings at least 2 years after a single treatment in patients from a phase 1/2 trial.
The first 5 of 14 adult men with hemophilia A and who had factor VIII (FVIII) activity of 2% or less before treatment with SPK-8011 (at single doses of either 5 × 1011 or 1 × 1012 vg/kg), showed no development of FVIII inhibitors or evidence of FVIII cellular immune response at 106-142 weeks’ follow-up after vector infusion, according to Lindsey A. George, MD, at the International Society of Thrombosis and Haemostasis 2020 virtual congress.
At follow-up, the two who had received a 5 × 1011 vg/kg dose had FVIII activity of 6.9%-8.4%, and the three in the 1 × 1012 vg/kg cohort had FVIII activity of 5.2%-19.8%, said Dr. George, of the Children’s Hospital of Philadelphia.
Overall, 12 of the 14 patients in the study had sustained FVIII expression, including 7 of 9 who received the highest SPK-8011 dose of 2 × 1012 vg/kg. In the 12 with sustained expression, a “remarkable” 91% reduction in the annualized bleeding rate from the year prior to vs. the year after vector infusion was observed, she said.
“Similarly, looking at number of factor infusions before vector infusion relative to the number of factor infusions after vector infusion ... [there was] evidence of remarkable preliminary efficacy,” she added, noting a 96% reduction in factor consumption.
The findings are of note because, while clinical studies of Spark Therapeutic’s SPK-8011 product in hemophilia B and preclinical models in hemophilia A showed promising reductions in bleeds and stable, durable levels of FVIII expression after therapy, the first successful clinical trial of an AAV-mediated gene therapy in hemophilia A – the BioMarin AAV serotype 5 human FVIII-SQ (valoctocogene roxaparvovec) – showed an unexpected decline in FVIII expression at 1, 2, 3, and 4 years.
“This may be particularly relevant in the context of development of multi-serotype AAV neutralizing antibodies (NAb) following AAV vector administration,” Dr. George said, referencing a small study in which she and her colleagues showed long-term persistence of cross-reactive AAV NAb. The findings of that study, which is currently in press in Molecular Therapy, “suggest that repeat AAV vector infusion is unlikely to be possible with current methods.”
Initial results from the SPK-8011 study were presented at the 2018 American Society of Hematology annual meeting. No major safety issues have emerged since those data were presented at ASH; no deaths have occurred, and none of the patients developed FVIII inhibitors.
Treatment-related adverse events were limited to an infusion reaction in one patient, which resolved completely, and liver enzyme elevations in three patients, which also resolved. One serious adverse event – a grade 2 transaminitis that resulted in elective hospitalization for intravenous steroid administration, also resolved.
With respect to vector clearance, there was “no evidence of vector in either saliva, semen, serum, urine, or peripheral blood mononuclear cells by 6 weeks after vector infusion,” Dr. George said.
One-stage assay determination of FVIII activity showed that activity greater than 10% permits an absolute bleeding rate (ABR) of less than 1%, which is consistent with hemophilia natural history studies. Therefore “these data support that FVIII activity that is approximately greater than 10% “may be adequate to either eliminate or achieve an ABR of less than 1,” she said.
“With respect to assay discrepancy, our data at least preliminarily support that the one-stage assay determinant of hepatocyte-derived FVIII correlates with clinical phenotype,” she added.
The findings in the first five patients demonstrate preliminary stability of FVIII expression at follow up between 2 and 3.3 years, she said.
Further, of the nine patients who received the 2 × 1012 vg/kg dose, seven had sustained FVIII expression at about 1.5 years, five of the seven had no bleeds, and two lost FVIII expression and returned to prophylaxis uneventfully, she noted.
“The future directions of this work are ultimately to explore the optimal vector dose and immunosuppression regimens to achieve predictable, safe, efficacious, and durable FVIII expression,” she said.
Asked during a question and answer period about potential reasons for the differences in durability seen with SBK-8011 versus valoctocogene roxaparvovec, Dr. George said they remain unclear but could be related to differences in vector doses and manufacturing platforms.
Emerging data may allow for better comparisons, she added.
Session moderator Sebastien Lacroix-Desmazes, MD, of Centre de Recherche des Cordeliers, Paris, further asked about plans to optimize the immunosuppression regimen.
Plans are indeed in the works to identify the optimal immunosuppression regimen and to optimize immunosuppression in this trial, Dr. George said, noting that Spark Therapeutics “has outlined a plan to further investigate this in phase 1/2 trial before progressing into phase 3 study.”
Spark Therapeutic sponsored the SPK-8011 study. Dr. George disclosed consulting and/or data safety monitoring board activity for Pfizer and AvroBio.
SOURCE: George L et al. 2020 ISTH Congress, Abstract OC 03.5.
SPK-8011, an investigational adeno-associated virus (AAV)–mediated gene therapy for hemophilia A, provides stable and durable factor VIII expression with no major safety concerns, according to findings at least 2 years after a single treatment in patients from a phase 1/2 trial.
The first 5 of 14 adult men with hemophilia A and who had factor VIII (FVIII) activity of 2% or less before treatment with SPK-8011 (at single doses of either 5 × 1011 or 1 × 1012 vg/kg), showed no development of FVIII inhibitors or evidence of FVIII cellular immune response at 106-142 weeks’ follow-up after vector infusion, according to Lindsey A. George, MD, at the International Society of Thrombosis and Haemostasis 2020 virtual congress.
At follow-up, the two who had received a 5 × 1011 vg/kg dose had FVIII activity of 6.9%-8.4%, and the three in the 1 × 1012 vg/kg cohort had FVIII activity of 5.2%-19.8%, said Dr. George, of the Children’s Hospital of Philadelphia.
Overall, 12 of the 14 patients in the study had sustained FVIII expression, including 7 of 9 who received the highest SPK-8011 dose of 2 × 1012 vg/kg. In the 12 with sustained expression, a “remarkable” 91% reduction in the annualized bleeding rate from the year prior to vs. the year after vector infusion was observed, she said.
“Similarly, looking at number of factor infusions before vector infusion relative to the number of factor infusions after vector infusion ... [there was] evidence of remarkable preliminary efficacy,” she added, noting a 96% reduction in factor consumption.
The findings are of note because, while clinical studies of Spark Therapeutic’s SPK-8011 product in hemophilia B and preclinical models in hemophilia A showed promising reductions in bleeds and stable, durable levels of FVIII expression after therapy, the first successful clinical trial of an AAV-mediated gene therapy in hemophilia A – the BioMarin AAV serotype 5 human FVIII-SQ (valoctocogene roxaparvovec) – showed an unexpected decline in FVIII expression at 1, 2, 3, and 4 years.
“This may be particularly relevant in the context of development of multi-serotype AAV neutralizing antibodies (NAb) following AAV vector administration,” Dr. George said, referencing a small study in which she and her colleagues showed long-term persistence of cross-reactive AAV NAb. The findings of that study, which is currently in press in Molecular Therapy, “suggest that repeat AAV vector infusion is unlikely to be possible with current methods.”
Initial results from the SPK-8011 study were presented at the 2018 American Society of Hematology annual meeting. No major safety issues have emerged since those data were presented at ASH; no deaths have occurred, and none of the patients developed FVIII inhibitors.
Treatment-related adverse events were limited to an infusion reaction in one patient, which resolved completely, and liver enzyme elevations in three patients, which also resolved. One serious adverse event – a grade 2 transaminitis that resulted in elective hospitalization for intravenous steroid administration, also resolved.
With respect to vector clearance, there was “no evidence of vector in either saliva, semen, serum, urine, or peripheral blood mononuclear cells by 6 weeks after vector infusion,” Dr. George said.
One-stage assay determination of FVIII activity showed that activity greater than 10% permits an absolute bleeding rate (ABR) of less than 1%, which is consistent with hemophilia natural history studies. Therefore “these data support that FVIII activity that is approximately greater than 10% “may be adequate to either eliminate or achieve an ABR of less than 1,” she said.
“With respect to assay discrepancy, our data at least preliminarily support that the one-stage assay determinant of hepatocyte-derived FVIII correlates with clinical phenotype,” she added.
The findings in the first five patients demonstrate preliminary stability of FVIII expression at follow up between 2 and 3.3 years, she said.
Further, of the nine patients who received the 2 × 1012 vg/kg dose, seven had sustained FVIII expression at about 1.5 years, five of the seven had no bleeds, and two lost FVIII expression and returned to prophylaxis uneventfully, she noted.
“The future directions of this work are ultimately to explore the optimal vector dose and immunosuppression regimens to achieve predictable, safe, efficacious, and durable FVIII expression,” she said.
Asked during a question and answer period about potential reasons for the differences in durability seen with SBK-8011 versus valoctocogene roxaparvovec, Dr. George said they remain unclear but could be related to differences in vector doses and manufacturing platforms.
Emerging data may allow for better comparisons, she added.
Session moderator Sebastien Lacroix-Desmazes, MD, of Centre de Recherche des Cordeliers, Paris, further asked about plans to optimize the immunosuppression regimen.
Plans are indeed in the works to identify the optimal immunosuppression regimen and to optimize immunosuppression in this trial, Dr. George said, noting that Spark Therapeutics “has outlined a plan to further investigate this in phase 1/2 trial before progressing into phase 3 study.”
Spark Therapeutic sponsored the SPK-8011 study. Dr. George disclosed consulting and/or data safety monitoring board activity for Pfizer and AvroBio.
SOURCE: George L et al. 2020 ISTH Congress, Abstract OC 03.5.
FROM THE 2020 ISTH CONGRESS
Liver biopsies show persistent FVIII after gene therapy for hemophilia A
Factor VIII expression was detected on liver biopsies at more than 2 years after a single infusion of adeno-associated virus (AAV) gene therapy for hemophilia A in two patients who were part of a recent phase 1/2 study and who participated in an optional liver biopsy substudy.
The persistent factor VIII (FVIII) expression seen in the two patients was consistent with the presence of circularized, full-length human FVIII-SQ DNA in the biopsy samples and was observed in one patients at week 201 after infusion with 6 x 1012 vg/kg of the AAV serotype 5 human FVIII-SQ gene therapy(valoctocogene roxaparvovec) and in another at week 140 after infusion with 4×1013 vg/kg, Sylvia Fong, PhD, reported during the International Society of Thrombosis and Haemostasis virtual congress.
The first patient had no FVIII detected in the plasma at the time of biopsy. The second had 28.4% of normal FVIII activity detected at the time of biopsy, said Dr. Fong of BioMarin Pharmaceutical, noting that alanine aminotransferase levels were normal at the time of biopsy for both subjects.
“Valoctocogene roxaparvovec is currently being evaluated in a phase 3 clinical study,” Dr. Fong said. “Data from the phase 1/2 trial have demonstrated preliminary proof of concept that valoctocogene roxaparvovec treatment, in many cases, eliminated spontaneous bleeds and the need for prophylactic factor VIII replacement.
“In addition, an acceptable safety profile was observed.”
Data from that trial were presented at the World Federation of Hemophilia virtual summit in June.
Liver biopsy for factor VIII expression
The current exploratory liver biopsy substudy – the first-in-human liver biopsy study after gene therapy for hemophilia A – was open to all phase 1/2 study participants and was initiated in September 2019 with multiple aims, including improved understanding of the durability and variability of AAV gene therapy, she explained.
Histopathological examination revealed normal liver architecture with mild steatosis and no evidence of steatohepatitis or significant inflammation in either participant. In the 6×1012 vg/kg– and 4×1013 vg/kg–treated participants, a dose-dependent increase was seen in the percentage of hepatocytes that stained positive for vector genomes (1.3% and 32%, respectively), she said.
“This was very exciting to see,” she said, referring to the 32% stain-positive rate in the patient who received the 4x1013 vg/kg dose. “Not only were we able to detect vector genomes more than 2 years post-dose, there seems to be quite a bit of signals in this patient sample.”
The findings were similar to those seen in preclinical nonhuman primate models, she noted.
liver hFVIII-SQ RNA levels were 7.67×102 copies/mcg and 6.77×104 copies/µg in the 6×1012 vg/kg–treated participant the 4×1013 vg/kg–treated participant, respectively.
The circularized genomes were present as monomers and concatemers in both participants, and “were presumably associated with long-term expression,” Dr. Fong said.
Both participants are clinically stable with no long-term hepatic issues, she said, noting that analyses of results from additional participants in the substudy will be shared as they become available.
To date, because of “precious small amounts” of tissue available from the biopsy samples, Dr. Fong said she and her colleagues had not looked for degradation of the vectors.
Session moderator Sebastien Lacroix-Desmazes, MD, of Centre de recherche des Cordeliers, Paris, asked: “Is there a plan [to do so] or not, because I guess it’s a very important point,” to which Dr. Fong said that it is a possibility if adequate samples become available.
Dr. Fong is an employee of BioMarin Pharmaceuticals.
SOURCE: Fong S. 2020 ISTH Congress, Abstract OC 03.4.
Factor VIII expression was detected on liver biopsies at more than 2 years after a single infusion of adeno-associated virus (AAV) gene therapy for hemophilia A in two patients who were part of a recent phase 1/2 study and who participated in an optional liver biopsy substudy.
The persistent factor VIII (FVIII) expression seen in the two patients was consistent with the presence of circularized, full-length human FVIII-SQ DNA in the biopsy samples and was observed in one patients at week 201 after infusion with 6 x 1012 vg/kg of the AAV serotype 5 human FVIII-SQ gene therapy(valoctocogene roxaparvovec) and in another at week 140 after infusion with 4×1013 vg/kg, Sylvia Fong, PhD, reported during the International Society of Thrombosis and Haemostasis virtual congress.
The first patient had no FVIII detected in the plasma at the time of biopsy. The second had 28.4% of normal FVIII activity detected at the time of biopsy, said Dr. Fong of BioMarin Pharmaceutical, noting that alanine aminotransferase levels were normal at the time of biopsy for both subjects.
“Valoctocogene roxaparvovec is currently being evaluated in a phase 3 clinical study,” Dr. Fong said. “Data from the phase 1/2 trial have demonstrated preliminary proof of concept that valoctocogene roxaparvovec treatment, in many cases, eliminated spontaneous bleeds and the need for prophylactic factor VIII replacement.
“In addition, an acceptable safety profile was observed.”
Data from that trial were presented at the World Federation of Hemophilia virtual summit in June.
Liver biopsy for factor VIII expression
The current exploratory liver biopsy substudy – the first-in-human liver biopsy study after gene therapy for hemophilia A – was open to all phase 1/2 study participants and was initiated in September 2019 with multiple aims, including improved understanding of the durability and variability of AAV gene therapy, she explained.
Histopathological examination revealed normal liver architecture with mild steatosis and no evidence of steatohepatitis or significant inflammation in either participant. In the 6×1012 vg/kg– and 4×1013 vg/kg–treated participants, a dose-dependent increase was seen in the percentage of hepatocytes that stained positive for vector genomes (1.3% and 32%, respectively), she said.
“This was very exciting to see,” she said, referring to the 32% stain-positive rate in the patient who received the 4x1013 vg/kg dose. “Not only were we able to detect vector genomes more than 2 years post-dose, there seems to be quite a bit of signals in this patient sample.”
The findings were similar to those seen in preclinical nonhuman primate models, she noted.
liver hFVIII-SQ RNA levels were 7.67×102 copies/mcg and 6.77×104 copies/µg in the 6×1012 vg/kg–treated participant the 4×1013 vg/kg–treated participant, respectively.
The circularized genomes were present as monomers and concatemers in both participants, and “were presumably associated with long-term expression,” Dr. Fong said.
Both participants are clinically stable with no long-term hepatic issues, she said, noting that analyses of results from additional participants in the substudy will be shared as they become available.
To date, because of “precious small amounts” of tissue available from the biopsy samples, Dr. Fong said she and her colleagues had not looked for degradation of the vectors.
Session moderator Sebastien Lacroix-Desmazes, MD, of Centre de recherche des Cordeliers, Paris, asked: “Is there a plan [to do so] or not, because I guess it’s a very important point,” to which Dr. Fong said that it is a possibility if adequate samples become available.
Dr. Fong is an employee of BioMarin Pharmaceuticals.
SOURCE: Fong S. 2020 ISTH Congress, Abstract OC 03.4.
Factor VIII expression was detected on liver biopsies at more than 2 years after a single infusion of adeno-associated virus (AAV) gene therapy for hemophilia A in two patients who were part of a recent phase 1/2 study and who participated in an optional liver biopsy substudy.
The persistent factor VIII (FVIII) expression seen in the two patients was consistent with the presence of circularized, full-length human FVIII-SQ DNA in the biopsy samples and was observed in one patients at week 201 after infusion with 6 x 1012 vg/kg of the AAV serotype 5 human FVIII-SQ gene therapy(valoctocogene roxaparvovec) and in another at week 140 after infusion with 4×1013 vg/kg, Sylvia Fong, PhD, reported during the International Society of Thrombosis and Haemostasis virtual congress.
The first patient had no FVIII detected in the plasma at the time of biopsy. The second had 28.4% of normal FVIII activity detected at the time of biopsy, said Dr. Fong of BioMarin Pharmaceutical, noting that alanine aminotransferase levels were normal at the time of biopsy for both subjects.
“Valoctocogene roxaparvovec is currently being evaluated in a phase 3 clinical study,” Dr. Fong said. “Data from the phase 1/2 trial have demonstrated preliminary proof of concept that valoctocogene roxaparvovec treatment, in many cases, eliminated spontaneous bleeds and the need for prophylactic factor VIII replacement.
“In addition, an acceptable safety profile was observed.”
Data from that trial were presented at the World Federation of Hemophilia virtual summit in June.
Liver biopsy for factor VIII expression
The current exploratory liver biopsy substudy – the first-in-human liver biopsy study after gene therapy for hemophilia A – was open to all phase 1/2 study participants and was initiated in September 2019 with multiple aims, including improved understanding of the durability and variability of AAV gene therapy, she explained.
Histopathological examination revealed normal liver architecture with mild steatosis and no evidence of steatohepatitis or significant inflammation in either participant. In the 6×1012 vg/kg– and 4×1013 vg/kg–treated participants, a dose-dependent increase was seen in the percentage of hepatocytes that stained positive for vector genomes (1.3% and 32%, respectively), she said.
“This was very exciting to see,” she said, referring to the 32% stain-positive rate in the patient who received the 4x1013 vg/kg dose. “Not only were we able to detect vector genomes more than 2 years post-dose, there seems to be quite a bit of signals in this patient sample.”
The findings were similar to those seen in preclinical nonhuman primate models, she noted.
liver hFVIII-SQ RNA levels were 7.67×102 copies/mcg and 6.77×104 copies/µg in the 6×1012 vg/kg–treated participant the 4×1013 vg/kg–treated participant, respectively.
The circularized genomes were present as monomers and concatemers in both participants, and “were presumably associated with long-term expression,” Dr. Fong said.
Both participants are clinically stable with no long-term hepatic issues, she said, noting that analyses of results from additional participants in the substudy will be shared as they become available.
To date, because of “precious small amounts” of tissue available from the biopsy samples, Dr. Fong said she and her colleagues had not looked for degradation of the vectors.
Session moderator Sebastien Lacroix-Desmazes, MD, of Centre de recherche des Cordeliers, Paris, asked: “Is there a plan [to do so] or not, because I guess it’s a very important point,” to which Dr. Fong said that it is a possibility if adequate samples become available.
Dr. Fong is an employee of BioMarin Pharmaceuticals.
SOURCE: Fong S. 2020 ISTH Congress, Abstract OC 03.4.
REPORTING FROM THE 2020 ISTH CONGRESS