BioMarin Pharmaceutical Inc. announced new data for valoctocogene roxaparvovec, an investigational gene therapy for the treatment of adults with severe hemophilia A, in its positive pivotal study, GENEr8-1, during an oral presentation at the International Society on Thrombosis and Haemostasis (ISTH) 2021 Virtual Congress. The pivotal study demonstrated superiority to Factor VIII prophylaxis in key clinical efficacy endpoints. With 134 participants, this is the large global Phase 3 study to date for gene therapy in hemophilia. All participants in the study received a single dose of valoctocogene roxaparvovec and completed a year or more of follow-up. Top-line one-year results from this study were previously communicated in January 2021. New data presented at ISTH include more details on annualized bleeding rate (ABR) in all study participants and annualized Factor VIII utilization rate, in terms of international units per kilogram per year (IU/kg/year) of replacement Factor VIII. Over 90% (N=134) of all participants in the GENEr8-1 study had an annualized bleed rate (ABR) of zero or a lower bleed rate than baseline after week 4 after treatment with valoctocogene roxaparvovec. New data presented at ISTH also include information on Factor VIII utilization after treatment with valoctocogene roxaparvovec. Mean annualized Factor VIII utilization rate, among a pre-specified group of prior participants in a non-interventional baseline observational study (rollover population; N=112) decreased from baseline on Factor VIII prophylaxis by 99% from 3961.2 (median 3754.4) to 56.9 (median 0) IU/kg/year after week 4 after treatment with valoctocogene roxaparvovec (p-value GENEr8-1 Study Description. The global Phase 3 GENEr8-1 study evaluates superiority of valoctocogene roxaparvovec at the 6e13 vg/kg dose compared to FVIII prophylactic therapy. All study participants had severe hemophilia A at baseline, defined as less than or equal to 1 IU/dL of Factor VIII activity. The study included 134 total participants, all of whom had a minimum of 12 months of follow-up at the time of the data cut. The first 22 participants were directly enrolled into the Phase 3 study, 17 of whom were HIV-negative and dosed at least 2 years prior to the data cut date (referred to as the subset). The remaining 112 participants (rollover population) completed at least six months in a separate non-interventional study to prospectively assess bleeding episodes, Factor VIII use, and health-related quality of life while receiving Factor VIII prophylaxis prior to rolling over to receive a single infusion of valoctocogene roxaparvovec in the GENEr8-1 study.