<i>In Vivo</i> panCAR-Mediated Depletion of B Cells in Non-Human Primates Using a Circular (oRNA®) Anti-CD20 CAR

While traditional ex vivo-generated chimeric antigen receptor (CAR) T cell therapies have had tremendous success in the clinic, manufacturing, safety, and accessibility challenges remain. The prospect of an in vivo CAR therapy without the need for patient cell isolation and culture and the safety risks associated with conditioning regimens remains a therapeutic goal. Orna Therapeutic's panCAR™ combines a synthetic, circular coding RNA platform (oRNA®) and proprietary immunotropic lipid nanoparticle (LNP) to drive CAR expression on the surface of immune effector cells (e.g. T cells, NK cells) after in vivo administration, promising a transient, re-dosable, and scalable immune cell therapy without the need for preconditioning lymphodepletion. Orna's panCAR technology leverages both a high-throughput LNP discovery engine, capable of unlocking LNP-mediated RNA delivery to extra-hepatic tissues, with a proprietary FoRCE platform capable of identifying oRNA-required IRES sequences that initiate protein translation in target cells. Our lead immunotropic LNP, LNP-6, delivers RNA cargo to 60% of splenic and 84% of peripheral blood T cells in non-human primates (NHP) using a reporter RNA cargo. When paired with an oRNA cargo, LNP-6 demonstrated up to ~70% delivery of an anti-CD20 CAR to NHP T cells and human T cells in vitro, maintaining expression over 72 hours. In cytotoxicity assays, both an anti-CD20 CAR and anti-CD19 CAR construct were able to kill human B lymphoblast cell lines in vitro. Using a humanized mouse model, an LNP-6-delivered anti-CD20 CAR oRNA showed significant B cell depletion in peripheral blood, spleen, and bone marrow at 24 hours (75-80% reduction) and sustained B cell depletion 7 days after dosing in the peripheral blood and bone marrow compartments. In NHPs, LNP-6 delivery of an anti-CD20 CAR oRNA resulted in a 95% reduction in B cells with sustained depletion (82%) 7 days after a single dose. These data support the opportunity for exploration of in vivo CAR therapies in oncologic disease settings.