Arbutus Biopharma

Arbutus Biopharma Corporation (NASDAQ: ABUS) is a clinical-stage biopharmaceutical company headquartered in Warminster, Pennsylvania developing a curative regimen for chronic hepatitis B virus (HBV) infection. The company employs a three-pronged strategy — suppress viral antigens, reduce HBV DNA, and boost the host immune system — using a combination of its lead RNAi therapeutic imdusiran (AB-729) with immunomodulators including AB-101, an oral PD-L1 inhibitor. As of July 2026 the company's lead program (IM-PROVE I and IM-PROVE II combination trials) is in Phase 2a and the company's mRNA delivery technology is also the subject of active patent litigation against Moderna and Pfizer/BioNTech over COVID-19 vaccine IP. Arbutus was originally incorporated in 2005 as OnCore BioPharma before merging with Tekmira Pharmaceuticals in 2015 and adopting the Arbutus name.