ASSEMBLY BIOSCIENCES, INC. 8-K

What Happened

• On May 22, 2026, Assembly Biosciences announced plans to broaden development of ABI-6250, its oral NTCP inhibitor originally being developed for chronic hepatitis delta virus (HDV), into cholestatic liver diseases—specifically primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC).
• ABI-6250 completed a Phase 1a study in healthy participants showing target engagement (dose-dependent increases in plasma total bile acids). The company completed chronic toxicology studies and says these support longer-term dosing in planned Phase 2 trials. A pre-IND meeting with the FDA was held and described as constructive.

Key Details

• Press release/8-K dated May 22, 2026 (Exhibit 99.1).
• ABI-6250 Phase 1a: completed in healthy volunteers; demonstrated pharmacodynamic signal consistent with NTCP inhibition.
• Planned clinical timeline: Phase 2 in HDV expected to start Q4 2026; Phase 2 basket study in PBC and PSC expected in Q1 2027, subject to regulatory feedback.
• Mechanism: ABI-6250 is an oral small-molecule inhibitor of the sodium taurocholate co-transporting polypeptide (NTCP), which blocks bile acid uptake into hepatocytes—a mechanism relevant to cholestatic diseases.

Why It Matters

• For investors, the move expands the potential addressable market for ABI-6250 beyond HDV into PBC and PSC. PBC has existing therapies but unmet needs for many patients; PSC currently has no approved treatments, representing a meaningful unmet medical need.
• The program has early supporting data (Phase 1a PD signal and completed chronic toxicology), but ABI-6250 remains investigational and its safety and efficacy in these diseases are not established. Timelines and trial starts are subject to regulatory feedback and clinical outcomes, so upcoming catalysts include the planned Phase 2 starts (HDV in Q4 2026; PBC/PSC basket in Q1 2027).