Assembly disassembles again

What happens when your back-up plan fails? The hepatitis B specialist Assembly Biosciences, already in the doldrums after its lead project disappointed last year, has now discontinued its next-in-line core inhibitor ABI-H2158 after seeing liver toxicity in a phase 2 study. The latest misstep raises more questions about the group’s clinical pipeline, which consists solely of core inhibitors. Assembly says its next-gen candidates, ABI-H3733 and ABI-4334, are “structurally distinct” from ABI-H2158, being built on a different chemical scaffold. But if core inhibitors are not the way forward in hep B Assembly now looks very exposed. The group has preclinical programmes against two undisclosed targets, plus a collaboration with Door Pharma covering core protein modulators. Meanwhile, Assembly’s lead asset, vebicorvir, is still in play, with data expected next year from two mid-stage triple combination studies. Still, expectations are not high for a project once expected to sell $1.6bn in 2026, according to Evaluate Pharma sellside consensus. Investors will now have to wait until 2023 for meaningful results from the next-gen core inhibitors, Leerink analysts noted. Assembly, whose shares opened down 17% this morning, has a cash runway to mid-2023.

Assembly Biosciences' core inhibitor pipeline*
Project Status
Vebicorvir (ABI-H0731) Failed ph2 Study 211; ph2s ongoing + ETV + peg-IFNα and + Nrtl + Arbutus's AB-729 
ABI-H2158 Discontinued following liver signal in ph2
ABI-H3733 Completed ph1a, data at upcoming meeting
ABI-4334 Clinical trials to start 2022
Note: *all for hep B; ETV= entecavir; Nrtl=nucleos(t)ide analogues; peg-IFNα=pegylated interferon alpha. Source: Evaluate Pharma & clinicaltrials.gov.

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