OC 11.5 - Lipid nanoparticles encapsulating FVIII transgene as re-dosable and safe gene therapy in hemophilia A

Background: Current hemophilia gene therapy, using viral vectors, confronts limitations such as safety risks and the inability to re-administration due to neutralizing antibodies. Non-viral gene therapy, employing lipid nanoparticles (LNPs), presents a promising new strategy with re-dosable potential and improved safety.

Aims: Explore whether the administration of LNPs encapsulating plasmid can achieve sustained and therapeutic level of FVIII in a re-dosable manner in preclinical animal models.

Methods: Two types of LNPs were generated using either the FDA-approved lipid, MC3, or a biodegradable cationic lipid (LipidA). These LNPs encapsulated plasmids comprising a CAG promoter and either secreted luciferase (LNP-scLuc) or FVIII-X10 variant (LNP-FVIII). Expression of scLuc and FVIII were detected in LNP injected C57BL/6 mice and HA-NSG mice, respectively. Hepatotoxicity was evaluated by measuring alanine transaminase (ALT) level in plasma.

Results: Mice injected with LipidA-LNP-scLuc exhibited significantly higher scLuc expression compared to MC3-LNP-scLuc at days 1 and 7, targeting 84.4% of hepatocytes in the liver. HA-NSG mice injected with LNP-FVIII at doses of 0.5 µg/g and 1 µg/g displayed approximately 11.8% and 23.0% FVIII activity, respectively. Re-administration of LNP-FVIII resulted in peak FVIII expression around 39.1% two weeks post-second injection. Sustained and detectable levels of FVIII expression was observed for more than 3 months. Moreover, no significant increase of plasma ALT level was detected in LNP-FVIII treated HA-NSG mice over initial 2 weeks suggesting no obvious hepatotoxicity.

Conclusion(s): Our findings illustrate the potential of LNPs to deliver FVIII transgene efficiently and safely as a non-viral gene therapy for hemophilia A, bypassing the risks associated with viral gene therapy. Moreover, the LNP platform allows re-administration to achieve sustained therapeutic FVIII expression.