Arbutus Provides AB-729 Clinical Data and AB-161 Preclinical Data as Oral Presentations at the Global Hepatitis Summit 2023

Seven patients with cHBV remain off all treatment and continue to maintain low levels of HBV DNA and HBsAg for at least one and half years post- AB-729 treatment

AB-161 provides robust anti-HBV activity including suppression of HBV RNA and HBsAg production in preclinical models                

WARMINSTER, Pa., April 27, 2023 (GLOBE NEWSWIRE) -- Arbutus Biopharma Corporation (Nasdaq: ABUS), a clinical-stage biopharmaceutical company leveraging its extensive virology expertise to develop novel therapeutics that target specific viral diseases, today announced that clinical data for AB-729, an RNAi therapeutic, and preclinical data for AB-161, a next-generation oral HBV specific RNA destabilizer, were presented as late-breaker oral presentations at the Global Hepatitis Summit 2023 in Paris.

Man-Fung Yuen, D.Sc., M.D., Ph.D., Chief of Division of Gastroenterology and Hepatology, Department of Medicine, The University of Hong Kong and principal investigator for the AB-729-001 clinical trial, presented data on nine patients with chronic hepatitis B virus infection (cHBV) who completed 48 weeks of treatment with AB-729, and 24 weeks later met protocol-defined criteria to also stop nucleos(t)ide analogue (NA) therapy. Two patients have restarted therapy – one at the investigator’s request after the week 20 visit which was previously presented at AASLD in November 2022, and one that met the protocol-defined HBV DNA criteria to restart NA therapy after the week 36 visit. In the 78% of patients (7 of 9) that remain off NA therapy for 44-64 weeks (over 1.5 years since last AB-729 dose), HBV DNA remains low and HBsAg remains below baseline (-0.8 to -1.6 log10 IU/mL). No adverse effects or ALT flares have occurred in these patients during follow-up.

“These data are extremely encouraging, especially the low levels of HBsAg and HBV DNA in most patients persisting for at least a year and a half after their last dose of AB-729. Furthermore, the lack of ALT flares experienced by these patients suggests that the host immune system is controlling the virus,” commented Professor Yuen. “AB-729 has a differentiated clinical profile compared to current treatment options for patients with cHBV, which include 48 weeks of interferon treatment or life-long NA therapy to keep HBV DNA levels suppressed. We look forward to continuing to monitor these patients for functional cure.”

Professor Yuen also presented post-treatment follow-up data for the seven HBV DNA negative, HBeAg positive patients (Cohort K) enrolled in the same trial. The mean log10 change from baseline in HBsAg was -2.57 IU/mL at week 48 (n=5) and -1.86 IU/mL at follow-up week 48 (n=5). Mean log decline in HBeAg was >1.0 log10 at the last follow up visit, even though HBeAg was low at baseline in some patients. One patient achieved both HBsAg and HBeAg less than the lower limit of quantitation (LLOQ = 0.07 IU/mL and = 0.11 IU/mL, respectively) with detectable anti-HBs antibodies. Two other patients achieved either HBsAg or HBeAg