Preclinical development of TAK-754, a high-performance AAV8-based vector expressing coagulation factor VIII

This report concerns the preclinical development of TAK-754, an AAV8-based human factor VIII (FVIII) vector designed to deliver a codon-optimized and CpG-depleted B domain-deleted <i>F8</i> transgene under the control of a liver-specific promoter for gene therapy in patients with hemophilia A. A dose-dependent increase in plasma FVIII activity was detected in FVIII knockout mice at a dose of 1.0 × 10¹² TAK-754 capsid particles (CP)/kg or higher. This increase was shown to be in accordance with a dose-dependent decrease in blood loss in a hemostatic efficacy assay. TAK-754 (3.1 × 10¹² CP/kg) mediated long-term and stable FVIII expression in immunologically tolerant transgenic human FVIII mice. Toxicology and biodistribution assessments with a single administration of TAK-754 ranging between 1.9 × 10¹² and 5.0 × 10¹³ CP/kg were conducted in male C57BL/6J mice. The highest TAK-754 dose occurred without TAK-754-related adverse clinical signs. Biodistribution profiling showed predominant detection in the liver with a low occurrence of vector DNA in other tissues. Integration site analysis revealed minimal vector integration, with no observations of clonal outgrowth or preferred integrations in genes previously implicated in hepatocellular carcinoma formation within the observation period. These preclinical studies demonstrate a good safety and efficacy profile for TAK-754.