Arbutus Presents New Data on AB-729, AB-836 and AB-101 at the EASL International Liver Congress™ 2022 and Provides AB-836 Clinical Update

AB-729, our RNAi therapeutic, provided robust and comparable HBsAg declines in both HBeAg+ and HBeAg- patients

50% (16 out of 32) of patients maintained HBsAg levels below 100 IU/mL 24 weeks after their last AB-729 dose

In the first five patients who discontinued both AB-729 and NA therapy after meeting stopping criteria, there has been no evidence of virologic or clinical relapse in 8-24 weeks of follow-up

Preliminary data to date have shown that AB-729 remains generally safe and well-tolerated after completing dosing in 41 patients

AB-729 continues to restore HBV-specific T-cells and decrease exhausted T-cells

AB-836, our oral capsid inhibitor, dosed at 100mg or 200mg once daily for 28 days, achieved mean declines in HBV DNA of 3.04 and 3.55 log10, respectively, however safety findings warrant further evaluation in healthy volunteers

AB-101, our oral PD-L1 inhibitor, mediates activation and reinvigoration of HBV-specific T-cells from chronic hepatitis B patients in a pre-clinical model

Conference Call and Webcast Scheduled for 8:00 AM ET, Monday, June 27, 2022

WARMINSTER, Pa., June 25, 2022 (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 the presentation of new clinical and pre-clinical data from its proprietary compounds at the European Association for the Study of the Liver (EASL) International Liver Congress™ (ILC).

The new clinical data for AB-729, our RNAi therapeutic, continues to support its development as a potential cornerstone agent for the treatment of chronic hepatitis B (cHBV) infection. In addition, when AB-729 and nucleos(t)ide analogues (NA) were discontinued in the first five patients who met stopping criteria and consented, there was no evidence of virologic or clinical relapse in at least 8-24 weeks of follow-up, which may lead to a functional cure.

AB-836, our oral capsid inhibitor, demonstrated robust antiviral activity, however, two patients in the 200 mg cohort experienced alanine aminotransferase (ALT) elevations. Based on these observations along with potentially correlated immunological findings, we plan to conduct a Phase 1 clinical trial in healthy volunteers before progressing this program.

William Collier, President and Chief Executive Officer of Arbutus, commented, “Our comprehensive AB-729 data package that has been accepted for presentation at EASL, is indicative of the continued impressive clinical safety and efficacy profile seen with AB-729 in 41 patients. Our clinical team has conducted a thorough evaluation of this compound in cHBV patients with different characteristics to identify an adequate dose and dosing schedule to move into our ongoing Phase 2a clinical trials which will support our Phase 2b clinical program. We believe that AB-729 is capable of being a cornerstone agent in the treatment regimen to provide a functional cure for patients with cHBV.”

AB-729-001 Clinical Data Poster PresentationsProfessor Man-Fung Yuen, D.Sc., M.D., Ph.D., Deputy Head of Department, Chief of Division of Gastroenterology and Hepatology, Master of Lap Chee, University of Hong Kong, and lead investigator of AB-729-001 clinical trial, presented a poster titled, “Continued suppression of viral markers observed following discontinuation of nucleos(t)ide analogue therapy in chronic hepatitis B subjects with low hepatitis B surface antigen levels after 48 weeks of treatment with AB-729”.

This presentation focused on the preliminary safety and virology data from those patients in part 3 of the AB-729-001 clinical trial who completed treatment with AB-729 and, after meeting the protocol-defined criteria, elected to stop their NA-therapy (n=9). Prof. Yuen reported on the first five of the nine patients that had between 8 and 24 weeks of data following discontinuation of all treatment.

The mean HBsAg for the five patients at baseline was 2887 IU/mL (range 1392-6765) compared to 69 IU/mL (range 4.58-150.1) at the last visit after discontinuing all treatment. All five patients remain off all treatment, and all have HBsAg levels below pre-baseline levels. None of the patients have met clinical or virologic relapse criteria. There were no adverse events (AEs) reported, no ALT elevations observed, and HBV DNA levels remain either less than the LLOQ (lower limit of quantification) or have transiently risen and subsequently decreased without intervention.