SEL-399

SEL-399 is a **Phase 1 human proof-of-concept co-administration regimen** developed by Selecta Biosciences and AskBio to evaluate immune tolerance induction against adeno-associated virus serotype 8. It combines **EMC-101**, an empty AAV8 capsid containing no DNA or transgene, with **ImmTOR**, a biodegradable nanoparticle formulation that encapsulates rapamycin. Rapamycin-mediated inhibition of mTOR is intended to induce antigen-specific immune tolerance to the co-administered AAV8 capsid, reducing formation of anti-AAV8 neutralizing antibodies and potentially enabling repeat dosing of AAV gene therapies. The study was conducted in healthy volunteers rather than patients with a specific disease.