Arbutus Biopharma Inc. announced clinical development milestones to advance its HBV pipeline. AB-729-201 is a Phase 2a clinical trial that is evaluating the safety, tolerability and antiviral activity of the combination of imdusiran, nucleos(t)ide analogue (NA) therapy and pegylated interferon alfa-2a (IFN) in patients with cHBV. Preliminary data presented at the EASL Congress in June 2023 suggest that the addition of IFN to imdusiran was generally well-tolerated and appears to result in continued HBsAg declines in some patients.

Arbutus plans to announce end-of-treatment data from this trial in the first half of 2024. AB-729-202 is a Phase 2a clinical trial that is evaluating the safety and immunogenicity of imdusiran, NA therapy and Barinthus Bio?s (formerly Vaccitech plc) VTP-300, an HBV antigen-specific immunotherapy. Preliminary data presented at AASLD ?

The Liver Meeting in November 2023 showed that the combination of imdusiran and VTP-300 provided a meaningful reduction of HBsAg levels that are maintained well below baseline. In addition, a subset of patients given imdusiran and then VTP-300 showed early signs of immune activation. Arbutus plans to announce end-of-treatment data from this portion of the trial in the first half of 2024.

AB-729-202 was amended to include an additional cohort of 20 patients who will receive imdusiran plus NA therapy for 24 weeks followed by VTP-300 plus up to two low doses of nivolumab, an approved anti-PD-1 monoclonal antibody. Enrollment is complete in this additional cohort with preliminary data expected in the second half of 2024. AB-729-203 is a Phase 2a clinical trial that will initiate in the first half of 2024 and will evaluate the safety, tolerability and antiviral activity of intermittent low doses of durvalumab, an approved PD-L1 monoclonal antibody in combination with imdusiran and NA therapy.