Arbutus Biopharma Corporation (Nasdaq: ABUS) has announced its corporate objectives for 2025, highlighting the planned initiation of a Phase 2b clinical trial for its RNAi therapeutic, imdusiran, in combination with interferon and nucleos(t)ide analogue (NA) therapy, for chronic hepatitis B virus (cHBV) infection. The trial is set to begin in the first half of 2025, building on promising Phase 2a results.
Imdusiran Phase 2b Trial Design
The planned placebo-controlled Phase 2b trial aims to enroll approximately 170 HBeAg-negative cHBV patients with baseline HBsAg levels ≤1000 IU/mL, subject to regulatory approval. This trial follows the IM-PROVE I Phase 2a clinical trial, which demonstrated a 50% functional cure rate (3/6) in HBeAg-negative patients with similar baseline HBsAg levels treated with six doses of imdusiran and 24 weeks of pegylated interferon alfa-2α (IFN), added to ongoing NA therapy. An overall functional cure rate of 25% (3/12) was observed in the broader study population. Patients achieving functional cure also seroconverted with high anti-HBs antibody levels. The combination therapy was generally safe and well-tolerated.
Michael J. McElhaugh, Interim President and Chief Executive Officer of Arbutus, stated, "The data we reported late last year from our IM-PROVE I Phase 2a clinical trial showed a meaningful functional cure rate and immune activation in cHBV patients… These data support our belief that imdusiran is differentiated from other RNAi therapeutics in development for HBV."
AB-101 Clinical Development
Arbutus is also progressing with the clinical development of AB-101, an oral PD-L1 inhibitor. The AB-101-001 Phase 1a/1b trial is evaluating the safety, tolerability, pharmacokinetics, and pharmacodynamics of single- and multiple-ascending doses of AB-101 in healthy subjects and cHBV patients. Part 3 of the trial, evaluating repeat doses of AB-101 for 28 days in cHBV patients, is underway. Data from the 10 mg cohort is expected in the first half of 2025. Arbutus will determine the next steps for AB-101 after evaluating data from Part 3 of this clinical trial.
Financial Position
Arbutus reported a strong financial position with approximately $123 million in cash, cash equivalents, and investments in marketable securities as of December 31, 2024 (unaudited). The company anticipates reducing its net cash burn in 2025 to a range of $47 to $50 million, compared to approximately $65 million in 2024 (unaudited). Arbutus believes its current resources and anticipated contractual milestones from Qilu Pharmaceutical will fund operations through the first quarter of 2028, including the imdusiran Phase 2b clinical trial.
