In Vivo pan CAR therapy utilizing circular RNA for treatment of multiple myeloma

Abstract Recently, traditional ex vivo-generated chimeric antigen receptor T (CAR-T) cell therapies have shown success in the clinic for oncology indications, specifically multiple myeloma. However, manufacturing, safety, and accessibility remain potential challenges in the ex vivo CAR-T approach to treat oncology patients. The prospect of an in vivo CAR-T cell therapy without the need for patient cell isolation and culture or the safety risks associated with preconditioning regimens remains a therapeutic goal. Orna Therapeutics' panCAR™ combines a synthetic, circular, coding RNA platform (oRNA®) and a proprietary immunotropic lipid nanoparticle (LNP) to drive CAR expression on the surface of immune effector cells after in vivo administration, with the potential to provide a transient, re-dosable, and scalable immune cell therapy without the need for preconditioning lymphodepletion. Utilizing a human and cynomolgus cross-reactive anti- B-cell maturation antigen (BCMA) panCAR in an immunotropic LNP, high surface expression of anti-BCMA panCAR was observed in a dose-dependent manner on human and cynomolgus immune cells and was maintained over at least 72hours in vitro. Additionally, expression of anti-BCMA panCAR was highly effective at killing BCMA-expressing target cells in in vitro killing assays. In an in vivo humanized mouse model engrafted with BCMA-expressing tumor cells, three weekly doses of 0.1 mg/kg anti-BCMA panCAR eliminated tumor for at least 30 days. Notably, in this setting, the anti-BCMA panCAR functionally outperformed both a panCAR containing a and a linear mRNA-LNP. In non-human primates (NHP), targeted ablation of over 95% of cynomolgus plasma cells was observed as early as 24 hours after a single dose of anti-BCMA panCAR. Depletion further increased to 98% at 48 hours and was sustained out to at least 72 hours. This targeted and durable depletion of plasma cells was consistent with a 100-fold decrease of plasma cell specific J-chain transcripts compared to a control arm at 48 and 72 hours. Critically, a significant impact on the overall B cell repertoire was not observed, highlighting the selectivity of anti-BCMA panCAR. Orna Therapeutics' platform provides a non-viral, transient, tunable, and scalable approach without the need for preconditioning lymphodepletion that shows robust activity in vitro and in vivo. Collectively, this pre-clinical data demonstrates the potential of Orna's in vivo oRNA panCAR therapy to treat a variety of plasma cell or BCMA related diseases including multiple myeloma.