WARMINSTER, PA — Arbutus Biopharma Corporation (Nasdaq: ABUS) has received clearance from the U.S. Food and Drug Administration to resume clinical development of its experimental hepatitis B treatment AB-101 in the United States, removing a regulatory restriction on the company’s oral immunotherapy program.
The Warminster-based biotechnology company said the FDA lifted the clinical hold on the drug’s Investigational New Drug application, allowing additional clinical testing to proceed.
Arbutus is evaluating its next development steps but has not specified when new trials might begin.
AB-101 is an experimental oral inhibitor of programmed death-ligand 1, or PD-L1, a protein involved in regulating immune responses.
The treatment is designed to block PD-L1 activity and potentially restore immune responses against hepatitis B virus in patients with chronic infection.
Arbutus previously completed a Phase 1a/1b clinical trial evaluating the drug’s safety, tolerability, pharmacokinetics and pharmacodynamics in healthy volunteers and patients with chronic hepatitis B.
The study examined single and multiple ascending oral doses to assess how the drug behaves in the body and affects its intended biological target.
According to the company, AB-101 was generally well tolerated in the completed trial.
Among patients with chronic hepatitis B, researchers observed high receptor occupancy in seven participants, indicating that the drug engaged its intended target.
Two patients receiving the 30-milligram dose also experienced declines in hepatitis B surface antigen, a marker associated with viral infection.
Those early findings suggest biological activity but do not establish that AB-101 can produce sustained viral control or a functional cure.
The removal of the clinical hold eliminates a regulatory barrier to further U.S. testing. It does not constitute FDA approval of the treatment or establish its clinical effectiveness.
Arbutus has not detailed the circumstances that led to the hold or the conditions surrounding its removal.
The company’s next decision will determine whether and how AB-101 advances beyond its completed early-stage study as a potential treatment for chronic hepatitis B.
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