BACKGROUNDValoctocogene roxaparvovec (AAV5-hFVIII-SQ) is an adeno-associated virus 5 (AAV5)-based gene-therapy vector containing a coagulation factor VIII complementary DNA driven by a liver-selective promoter. The efficacy and safety of the therapy were previously evaluated in men with severe hemophilia A in a phase 1-2 dose-escalation study. METHODSWe conducted an open-label, single-group, multicenter, phase 3 study to evaluate the efficacy and safety of valoctocogene roxaparvovec in men with severe hemophilia A, defined as a factor VIII level of 1 IU per deciliter or lower. Participants who were at least 18 years of age and did not have preexisting anti-AAV5 antibodies or a history of development of factor VIII inhibitors and who had been receiving prophylaxis with factor VIII concentrate received a single infusion of 6×10 13 vector genomes of valoctocogene roxaparvovec per kilogram of body weight. The primary end point was the change from baseline in factor VIII activity (measured with a chromogenic substrate assay) during weeks 49 through 52 after infusion. Secondary end points included the change in annualized factor VIII concentrate use and bleeding rates. Safety was assessed as adverse events and laboratory test results. RESULTSOverall, 134 participants received an infusion and completed more than 51 weeks of follow-up. Among the 132 human immunodeficiency virus-negative participants, the mean factor VIII activity level at weeks 49 through 52 had increased by 41.9 IU per deciliter (95% confidence interval [CI], 34.1 to 49.7; P<0.001; median change, 22.9 IU per deciliter; interquartile range, 10.9 to 61.3). Among the 112 participants enrolled from a prospective noninterventional study, the mean annualized rates of factor VIII concentrate use and treated bleeding after week 4 had decreased after infusion by 98.6% and 83.8%, respectively (P<0.001 for both comparisons). All the participants had at least one adverse event; 22 of 134 (16.4%) reported serious adverse events. Elevations in alanine aminotransferase levels occurred in 115 of 134 participants (85.8%) and were managed with immune suppressants. The other most common adverse events were headache (38.1%), nausea (37.3%), and elevations in aspartate aminotransferase levels (35.1%). No development of factor VIII inhibitors or thrombosis occurred in any of the participants. CONCLUSIONSIn patients with severe hemophilia A, valoctocogene roxaparvovec treatment provided endogenous factor VIII production and significantly reduced bleeding and factor VIII concentrate use relative to factor VIII prophylaxis. (Funded by BioMarin Pharmaceutical; GENEr8-1 ClinicalTrials.gov number, NCT03370913.

BackgroundBAY 81-8973 is a new full-length human recombinant factor VIII product manufactured with technologies to improve consistency in glycosylation and expression to optimize clinical performance.ObjectivesTo demonstrate superiority of prophylaxis vs. on-demand therapy with BAY 81-8973 in patients with severe hemophilia A.Patients/MethodsIn this multinational, randomized, open-label crossover study (LEOPOLD II; ClinicalTrials.gov identifier: NCT01233258), males aged 12–65 years with severe hemophilia A were randomized to twice-weekly prophylaxis (20–30 IU kg−1), 3-times-weekly prophylaxis (30–40 IU kg−1), or on-demand treatment with BAY 81-8973. Potency labeling for BAY 81-8973 was based on the chromogenic substrate assay or adjusted to the one-stage assay. Primary efficacy endpoint was annualized number of all bleeds (ABR). Adverse events (AEs) and immunogenicity were also assessed.ResultsEighty patients (on demand, n = 21; twice-weekly prophylaxis, n = 28; 3-times-weekly prophylaxis, n = 31) were treated and analyzed. Mean ± SD ABR was significantly lower with prophylaxis (twice-weekly, 5.7 ± 7.2; 3-times-weekly, 4.3 ± 6.5; combined, 4.9 ± 6.8) vs. on-demand treatment (57.7 ± 24.6; P < 0.0001, anova). Median ABR was reduced by 97% with prophylaxis (twice-weekly, 4.0; 3-times-weekly, 2.0; combined, 2.0) vs. on-demand treatment (60.0). Median ABR was higher with twice-weekly vs. 3-times-weekly prophylaxis during the first 6-month treatment period (4.1 vs. 2.0) but was comparable in the second 6-month period (1.1 vs. 2.0). Few patients reported treatment-related AEs (4%); no treatment-related serious AEs or inhibitors were reported.ConclusionsTwice-weekly or 3-times-weekly prophylaxis with BAY 81-8973 reduced median ABR by 97% compared with on-demand therapy, confirming the superiority of prophylaxis. Treatment with BAY 81-8973 was well tolerated.

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Neutralizing antibodies (inhibitors) to replacement Factor-VIII impair the effective management of hemophilia-A1. Individuals with hemophilia-A due to major F8 gene disruptions lack antigenically cross-reactive material in their plasma (CRM-negative) and prevalence of inhibitors is >60%. Conversely, subjects with missense mutations are CRM-positive and the prevalence of inhibitors is <10%2. Individuals with the intron-22-inversion (~50% of individuals with severe hemophilia-A) should be in the former group based on the genetic defect. Although these individuals are CRM-negative, only 20% of them develop inhibitors3. Here we demonstrate the presence of comparable levels of F8 mRNA and intracellular Factor-VIII protein in B-lymphoblastoid cells and liver biopsies from healthy controls and subjects with the intron-22-inversion. These results support the hypothesis that most individuals with the intron-22-inversion are tolerized to Factor-VIII and thus do not develop inhibitors. Furthermore we developed a pharmacogenetic algorithm that permits the stratification of inhibitor risk for sub-populations by predicting immunogenicity using, as input, the number of putative T-cell epitopes in the infused FVIII and the competence of MHC-Class-II molecules to present such epitopes. The algorithm exhibited significant accuracy in predicting inhibitors in 25 unrelated individuals with the intron-22-inversion (AUC = 0.890; P = 0.001).