NTCP inhibitor pivoting from HDV into PBC/PSC on Phase 1a biomarker data only — Phase 2 initiation tests whether target engagement translates to clinical benefit

Assembly Biosciences is a clinical-stage company developing an oral targeted therapy for hepatitis delta virus infection and cholestatic liver diseases, not yet approved.

Assembly Bio rebuilt around ABI-6250, an oral NTCP inhibitor targeting hepatitis delta virus and cholestatic liver diseases, after Gilead passed on its HBV asset and absorbed the herpes program. The thesis resolves on whether ABI-6250 Phase 2 data in HDV or PBC/PSC demonstrates clinical efficacy, not merely target engagement. The lead risk is that registrational programs rest entirely on Phase 1a biomarker signals, a thin foundation for two separate disease expansions simultaneously.