Assembly Biosciences and Arbutus Biopharma Initiate Phase 2 Clinical Trial of Triple Combination Therapy for the Treatment of Chronic Hepatitis B Virus

Trial will evaluate Assembly’s core inhibitor candidate, vebicorvir, with Arbutus’ RNAi therapeutic candidate, AB-729, and standard-of-care NrtI therapy

SOUTH SAN FRANCISCO, Calif., and WARMINSTER, Pa., Feb. 26, 2021 (GLOBE NEWSWIRE) -- Assembly Biosciences, Inc. (Nasdaq: ASMB) and Arbutus Biopharma Corporation (Nasdaq: ABUS) today announced the initiation of a Phase 2 clinical trial of Assembly Bio’s investigational hepatitis B virus (HBV) core inhibitor candidate, also known as a capsid inhibitor, vebicorvir (VBR), in combination with Arbutus’ proprietary GalNAc delivered RNAi therapeutic candidate, AB-729, and standard-of-care nucleos(t)ide reverse transcriptase inhibitor (NrtI) therapy for the treatment of patients with chronic HBV infection. The companies announced a clinical collaboration agreement in August 2020.

The randomized, multi-center, open-label Phase 2 clinical trial will evaluate the safety, pharmacokinetics, and antiviral activity of the triple combination of VBR, AB-729 and an NrtI compared to the double combinations of VBR with an NrtI and AB-729 with an NrtI. Approximately 60 virologically-suppressed patients with HBeAg negative chronic HBV are expected to be enrolled across these three treatment arms. Patients will be dosed for 48 weeks with VBR 300 mg orally once daily and AB-729 60 mg subcutaneously every 8 weeks, with a 48-week follow-up period. The primary objective of the trial is to evaluate the safety and tolerability of the triple combination, while secondary objectives of the trial include evaluating the effect of the triple combination in reducing HBV viral biomarkers such as HBV DNA, HBV pgRNA and HBsAg. Additional cohorts may be added in the future to evaluate other patient populations and/or combinations.

“We are excited to move forward with our collaborators in this proof-of-concept Phase 2 clinical trial designed to evaluate multiple complementary mechanisms of action. Importantly, this trial supports our long-standing belief that multi-drug combinations will be needed to provide patients with chronic hepatitis B a much needed and durable functional cure,” stated Gaston Picchio, PhD, Chief Development Officer at Arbutus. “We believe reducing HBsAg will be a key component of future HBV curative therapies. AB-729, Arbutus’ lead HBV asset, has demonstrated competitive HBsAg reductions and a favorable safety and tolerability profile in an ongoing Phase 1b clinical trial, and we are gratified to have it progress in this combination trial.”