Summary/Abstract Hemophilia is an inherited bleeding disorder caused by a deficiency of the functional clotting factor FVIII (hemophilia A) or FIX (hemophilia B) in the contact activation pathway of the coagulation cascade. Current treatment by protein replacement therapy is constrained by the short half-life of the clotting factors, requiring repeated infusions at relatively large doses. The development of inhibitors (alloantibodies to clotting factors) remains the single most important obstacle to managing hemophilia with protein therapy. Approximately 20–30% of patients with hemophilia A and 5% of patients with hemophilia B develop inhibitors after protein replacement therapy. In patients with inhibitors, the administration of clotting factors is ineffective, and poor control of hemorrhagic episodes increases complications associated with the disease. Bispecific Factor IXa and X-directed antibodies can be given to hemophilia A patients with or without inhibitors and are an improvement over infusions. However, 47% of patients still require infusions for breakthrough bleeds. Hemophilia A gene therapies in development for non-inhibitor patients have demonstrated limited durability of effect after a single infusion. To date there have been no approved AAV based gene therapies in development for hemophilia patients with inhibitors. GeneVentiv is directly addressing this critical unmet need through the development of GENV-HEM, the first universal gene therapy for all hemophilias and the first designed to treat inhibitor patients. GENV-HEM is an AAV8 vector encoding human FVa (hFVa) driven by a liver-specific promoter. Within the coagulation pathway, FVa functions downstream as a co-factor of activated Factor X (FXa) to amplify thrombin generation. FVa acts in the common coagulation pathway and can generate thrombin via the prothrombinase complex without FVIII or Factor IX. GENV-HEM offers a potential platform therapy that can treat multiple types of hemophilia including hemophilia A and B with or without inhibitors and FV deficiency, including multi-year durability of effect. We have demonstrated proof-of-concept in mouse models of hemophilia. The next major steps to allow commercialization of this innovative technology are encompassed in the following Specific Aims: (1) Optimization of lead GENV- HEM candidate in a mouse model of hemophilia with a reduced minimum effective dose; (2) Manufacture GLP- grade GENV-HEM for IND-enabling studies; (3) Demonstrate efficacy of GENV-HEM in a canine model of hemophilia; and (4) Develop bioanalytical methods in nonhuman primates in preparation for IND-enabling pharmacology/toxicology studies. This data resulting from these studies will be used to inform IND-enabling studies in dog and NHPs and predict starting doses for Phase 1 clinical trials. The successful outcome of this Direct to Phase II project will support the commercialization of a technology that bypasses missing factors VIII or IX and any inhibitors,...