Arbutus Biopharma Corporation announced on October 22, 2026, that the U.S. Food and Drug Administration (FDA) has removed the clinical hold on its Investigational New Drug (IND) application for AB-101. The company stated that it has been notified by the FDA that the hold has been lifted, allowing the company to proceed with additional clinical development for AB-101 in the United States.
AB-101 is a proprietary oral PD-L1 inhibitor designed to activate a patient’s hepatitis B virus (HBV)-specific immune response by inhibiting PD-L1. The candidate is intended to allow for controlled checkpoint blockade while minimizing systemic safety issues typically associated with checkpoint antibody therapies.
The company reported that AB-101 has completed a Phase 1a/1b clinical trial (AB-101-001). This trial evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of single- and multiple-ascending oral doses in healthy subjects and patients with chronic HBV infection. According to the filing, data from healthy subjects in Parts 1 and 2 and cHBV patients in Part 3 showed that AB-101 was generally well-tolerated. The data included evidence of high receptor occupancy in seven cHBV patients and a decline in hepatitis B surface antigen in two cHBV patients at the 30mg dose.
Arbutus is currently evaluating next steps for the continued development of AB-101. The company is also developing imdusiran (AB-729) for the treatment of cHBV infection. Additionally, Arbutus is consulting with its exclusive licensee, Genevant Sciences, regarding intellectual property matters related to its LNP technology, which is the subject of ongoing lawsuits against Pfizer Inc. and BioNTech SE.
