rAAV8 encapsidated HMR-001/z enables high efficiency hepatic transduction and restores hemostasis in hemophilic mice.

Abstract

Hemophilia A (HA), an X-linked bleeding disorder caused by factor VIII (FVIII) deficiency, is primarily managed with exogenous therapeutic agents; however, this treatment approach remains burdensome and fails to provide durable hemostatic control. Adeno-associated viral (AAV) vectors enabling endogenous FVIII expression have emerged as promising alternatives to address these limitations, but existing vectors show limited transduction efficiency and declining activity over time. Here, we report the development and preclinical evaluation of two bioengineered AAV8 vectors, HMR-001 and its codon-optimized variant HMR-001z, designed to enhance genome integrity, hepatocellular delivery, and translational efficiency. In hemophilia A mice, intravenous administration of HMR-001 induced dose-dependent and sustained FVIII expression, achieving substantial hemostatic improvement at the highest investigated dose (2 × 10¹³ vg/kg), with blood loss reduced to levels comparable to Xyntha prophylaxis. High-order triple-linkage ddPCR quantification revealed dose-dependent increases in full-length vector genome abundance, reaching 3.74, 21.55, and 48.52 copies per diploid genome at doses of 2 × 10¹², 8 × 10¹², and 2 × 10¹³ vg/kg, respectively. Building on these markedly improved genome delivery and preservation profiles, HMR-001z achieved complete hemostatic correction at a dose of 1 × 10¹³ vg/kg, exhibiting approximately 30-fold higher FVIII expression than HMR-001 and reaching ~400 IU/dL. Collectively, these findings demonstrate that genome-level optimization combined with codon-usage refinement synergistically enhances AAV8-mediated FVIII expression, establishing HMR-001z as a durable and translationally advanced gene therapy candidate for hemophilia A.