Assembly Bio reports Phase 1a safety win for NTCP inhibitor ABI-6250
Assembly Biosciences has disclosed positive Phase 1a results for ABI-6250, its investigational oral inhibitor of the sodium taurocholate co-transporting polypeptide (NTCP), ahead of presentations at the American Association for the Study of Liver Diseases annual meeting in Denver in November 2026.
The randomised, blinded study in healthy participants found ABI-6250 to be well tolerated across doses evaluated, with no serious adverse events reported. The compound produced dose-dependent, reversible increases in total and conjugated bile acids, a pharmacodynamic signature the company says is consistent with on-target NTCP inhibition. The pharmacodynamic analysis has been designated a Poster of Distinction at the conference, an honour awarded to a subset of submissions judged of particular scientific merit.
Clinical path
On the basis of these findings, Assembly Bio intends to initiate a Phase 2 study in patients with chronic hepatitis delta virus (HDV) infection in the fourth quarter of 2026, followed by a Phase 2 programme in cholestatic liver diseases, specifically primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC), in the first quarter of 2027.
Anuj Gaggar, chief medical officer, said the results "support ABI-6250's safety profile and demonstrate potent target engagement," adding that the company looks forward to sharing the data with the hepatology community as it readies its Phase 2 plans.
NTCP serves a dual function: it transports bile acids into hepatocytes and acts as the entry receptor for both HBV and HDV. Blocking NTCP is a clinically validated mechanism for preventing HDV infection, and inhibiting bile acid uptake is a plausible strategy in cholestatic conditions where bile acid accumulation drives hepatic inflammation and injury. ABI-6250's oral bioavailability distinguishes it from some earlier entrants in the NTCP space, which have included injectable candidates.
Market context
HDV is a satellite virus requiring HBV co-infection to replicate, affecting an estimated 15 to 20 million people globally. Until recently, treatment options were limited to interferon-based regimens with modest efficacy and significant tolerability burdens. Bulevirtide, approved in the EU in 2020 and now carrying full EMA approval, established proof of concept for entry inhibition at NTCP and provides a reference point against which ABI-6250 will ultimately need to demonstrate differentiation, whether on dosing convenience, potency, or breadth of liver disease utility.
The cholestatic disease angle broadens ABI-6250's potential commercial footprint considerably. PBC and PSC are chronic, progressive conditions with significant unmet need; approved therapies in PBC have expanded in recent years but the market remains active for new mechanisms. Assembly Bio's dual development programme in viral and non-viral liver indications is a notable strategic choice, concentrating risk in the hepatology space while potentially creating synergies in patient access and clinical infrastructure.
Assembly Bio has previously disclosed a collaboration with Gilead Sciences, which is referenced in the company's standard forward-looking statement boilerplate. The press release does not describe any Gilead involvement in the ABI-6250 programme specifically; editors may wish to seek clarification on how that collaboration intersects with the current development timeline.
Both posters are scheduled for presentation on 7 November 2026 and will be made available on Assembly Bio's website after the conference.