Arbutus Announces Additional Robust HBsAg Decline Data with AB-729 in Chronic Hepatitis B Subjects

Data released today expands on November 15, 2020 AASLD presentation

Repeat dosing of 60 mg AB-729 every 4 weeks resulted in robust and continuous mean declines in HBsAg decline at week 20 (-1.71 log10IU/mL, N=7) and further reductions continued beyond week 20 (-1.84 log10 IU/mL, N=3)

In HBV DNA positive subjects, a single 90 mg AB-729 dose resulted in robust mean declines in HBsAg (-1.02 log10 IU/mL), HBV DNA (-1.53 log10 IU/mL), HBV RNA and HBcrAg at week 12

Results support advancement into Phase 2 combination clinical trials with AB-729 dosing as infrequently as every 8 or 12 weeks

Conference Call and Webcast Scheduled Today at 8:00 am ET

WARMINSTER, Pa., Nov. 16, 2020 (GLOBE NEWSWIRE) --  Arbutus Biopharma Corporation (Nasdaq: ABUS), a clinical-stage biopharmaceutical company primarily focused on developing a cure for people with chronic hepatitis B virus (HBV) infection as well as therapies to treat coronaviruses (including COVID-19), today announced additional clinical data from an ongoing Phase 1a/1b clinical trial (AB-729-001) with AB-729, its proprietary GalNAc delivered RNAi compound.

The new data described today expands on the presentation entitled Safety and pharmacodynamics of the GalNAc-siRNA AB-729 in subjects with chronic hepatitis B infection, recorded on October 14, 2020 and presented on November 15, 2020 by Professor Man-Fung Yuen, D.Sc., M.D., Ph.D., from the University of Hong Kong at The Liver Meeting Digital Experience^TM, The American Association for the Study of Liver Diseases (AASLD) Meeting.

The new data summarized below include HBsAg data for the complete 60 mg every 4 weeks multi-dose cohort (N=7) at week 20, and the first results for the AB-729 90 mg single-dose cohort of HBV DNA positive subjects (N=5).

William Collier, President and Chief Executive Officer of Arbutus, stated, “The positive data described today, together with the strong safety and efficacy results presented by Professor Yuen at AASLD yesterday, are encouraging and continue to support our confidence in the therapeutic value of AB-729 as we plan to move into Phase 2 clinical trials.”

Summary of new data

Repeat dosing of AB-729 60 mg every 4 weeks results in continuous declines in mean HBsAg through week 20 (Cohort E)

	Mean (SE) Week 16 N=7	Mean (SE) Week 20 N=7	Mean (SE) Week 24 N=3
Δlog10 HBsAg (IU/mL)	-1.44 (0.18)	-1.71 (0.18)	-1.84 (0.10)

Dr. Gaston Picchio, Chief Development Officer at Arbutus stated, “Further follow up of the 60 mg every 4 weeks multi-dose cohort confirmed continuous reductions in mean HBsAg at week 20 (N=7), and in a subset of subjects (N=3) beyond this time point, while being generally safe and well tolerated. Additionally, the mean HBsAg declines and slopes of declines are similar between single doses and repeat doses of AB-729 up to week 12. Importantly, this suggests that dosing AB-729 as frequently as every 4 weeks may not be necessary, and that AB-729 has the potential to be dosed every 8 weeks or even every 12 weeks. This dosing strategy is being investigated in other cohorts of the trial with results from the 60 mg every 8 week cohort expected before the end of 2020.”