Adeno-associated virus (AAV) vectors are a leading platform for gene-based therapies for both monogenic and complex acquired disorders. The success of AAV gene transfer highlights the need to answer ...outstanding clinical questions of safety, durability, and the nature of the human immune response to AAV vectors. Here, we present longitudinal follow-up data of subjects who participated in the first trial of a systemically delivered AAV vector. Adult males (n = 7) with severe hemophilia B received an AAV2 vector at doses ranging from 8 × 1010 to 2 × 1012 vg/kg to target hepatocyte-specific expression of coagulation factor IX; a subset (n = 4) was followed for 12–15 years post-vector administration. No major safety concerns were observed. There was no evidence of sustained hepatic toxicity or development of hepatocellular carcinoma as assessed by liver transaminase values, serum α-fetoprotein, and liver ultrasound. Subjects demonstrated persistent, increased AAV neutralizing antibodies (NAbs) to the infused AAV serotype 2 (AAV2) as well as all other AAV serotypes tested (AAV5 and AAV8) for the duration of follow-up. These data represent the longest available longitudinal follow-up data of subjects who received intravascular AAV and support the preliminary safety of intravascular AAV administration at the doses tested in adults. Data demonstrate, for the first time, the persistence of high-titer, multi-serotype cross-reactive AAV NAbs for up to 15 years post- AAV vector administration. Our observations are broadly applicable to the development of AAV-mediated gene therapy.
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Presented here are the longest available longitudinal follow-ups of human subjects following intravascular adeno-associated virus (AAV) vector administration. These data support the preliminary long-term safety of systemic AAV delivery and demonstrate the persistence of high-titer, multi-serotype, cross-reactive AAV NAbs for up to 15 years after vector infusion.
Endogenous and exogenous hormones have significant effects on coagulation and may tip the hemostatic balance toward thrombosis. The endogenous hormonal changes in pregnancy and polycystic ovary ...syndrome, and exogenous hormonal contraception, menopause replacement, and transgender cross-hormone replacement may increase thromboembolism risk. Using the lowest effective dose is critical for prevention, but once thrombosis occurs, anticoagulation may be required, in some, long term. We review the relative risk of thrombosis in these conditions, risk factors, and anticoagulation treatment and prevention. Implementation of lowest effective hormonal therapies, thrombosis reduction strategies, and current anticoagulation management are critical for optimal patient outcomes.
The goal of gene therapy for patients with hemophilia A is to safely impart long-term stable factor VIII expression that predictably ameliorates bleeding with the use of the lowest possible vector ...dose.
In this phase 1-2 trial, we infused an investigational adeno-associated viral (AAV) vector (SPK-8011) for hepatocyte expression of factor VIII in 18 men with hemophilia A. Four dose cohorts were enrolled; the lowest-dose cohort received a dose of 5 × 10
vector genomes (vg) per kilogram of body weight, and the highest-dose cohort received 2 × 10
vg per kilogram. Some participants received glucocorticoids within 52 weeks after vector administration either to prevent or to treat a presumed AAV capsid immune response. Trial objectives included evaluation of the safety and preliminary efficacy of SPK-8011 and of the expression and durability of factor VIII.
The median safety observation period was 36.6 months (range, 5.5 to 50.3). A total of 33 treatment-related adverse events occurred in 8 participants; 17 events were vector-related, including 1 serious adverse event, and 16 were glucocorticoid-related. Two participants lost all factor VIII expression because of an anti-AAV capsid cellular immune response that was not sensitive to immune suppression. In the remaining 16 participants, factor VIII expression was maintained; 12 of these participants were followed for more than 2 years, and a one-stage factor VIII assay showed no apparent decrease in factor VIII activity over time (mean ±SD factor VIII activity, 12.9±6.9% of the normal value at 26 to 52 weeks when the participants were not receiving glucocorticoids vs. 12.0±7.1% of the normal value at >52 weeks after vector administration; 95% confidence interval CI, -2.4 to 0.6 for the difference between matched pairs). The participants had a 91.5% reduction (95% CI, 88.8 to 94.1) in the annualized bleeding rate (median rate, 8.5 events per year range, 0 to 43.0 before vector administration vs. 0.3 events per year range, 0 to 6.5 after vector administration).
Sustained factor VIII expression in 16 of 18 participants who received SPK-8011 permitted discontinuation of prophylaxis and a reduction in bleeding episodes. No major safety concerns were reported. (Funded by Spark Therapeutics and the National Heart, Lung, and Blood Institute; ClinicalTrials.gov numbers, NCT03003533 and NCT03432520.).
Background
Fitusiran, an investigational small interfering RNA therapy, reduces antithrombin production to rebalance hemostasis in people with hemophilia A or B, with or without inhibitors.
...Objectives
To evaluate the safety and efficacy of fitusiran treatment for people with moderate/severe hemophilia A or B with inhibitors.
Patients/Methods
In this open‐label phase 1, part D study, 17 males with hemophilia A or B with inhibitors received three once‐monthly subcutaneous injections of fitusiran 50 mg (n = 6) or 80 mg (n = 11); followed for up to 112 days. Endpoints included safety (primary), pharmacokinetics/pharmacodynamics (secondary), annualized bleeding rate, and patient‐reported outcomes (exploratory).
Results
The most common adverse event was injection site erythema (n = 8). No thrombotic events were reported. At nadir, mean (standard error of the mean SEM) antithrombin activity decreased from baseline by 82.0% (2.2) and 87.4% (0.7) in the 50 mg and 80 mg groups, respectively. Antithrombin reduction was associated with increased thrombin generation. 11/17 (64.7%) participants had no bleeds during the observation period (mean standard deviation 69.4 16.3 days). Mean (SEM) changes from baseline in Haemophilia Quality of Life Questionnaire for Adults total (−9.2 2.9) and physical health (−12.3 3.9) domain scores suggested clinically meaningful improvement.
Conclusions
Monthly fitusiran was generally well tolerated, lowered antithrombin levels from baseline, and resulted in improved thrombin generation. These preliminary results suggest that monthly fitusiran treatment may reduce bleeding episodes and improve quality of life in participants with hemophilia A or B with inhibitors.
Hemophilia A (Factor VIII Deficiency) Seaman, Craig D; Xavier, Frederico; Ragni, Margaret V
Hematology/oncology clinics of North America,
12/2021, Volume:
35, Issue:
6
Journal Article
Peer reviewed
Remarkable changes are occurring in the diagnosis and management of individuals with hemophilia A. Genetic testing, including next-generation sequencing, enables family planning, carrier testing, and ...prenatal diagnosis. Musculoskeletal ultrasound examination facilitates the early detection of acute bleeds and joint disease in clinic, enabling more rapid bleed resolution and treatment planning. Novel therapies offer simpler weekly or monthly administration, some by subcutaneous injection, with better compliance and quality of life, as well as fewer bleeds. Gene therapy provides a 1-time phenotypic "cure" that is cost effective, but may be complicated by waning levels, vector immune responses, and hepatotoxicity.
WFH Guidelines for the Management of Hemophilia, 3rd edition Srivastava, Alok; Santagostino, Elena; Dougall, Alison ...
Haemophilia : the official journal of the World Federation of Hemophilia,
August 2020, 2020-08-00, 20200801, 2020-08-01, Volume:
26, Issue:
S6
Journal Article
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