Arbutus Biopharma shares rise 15.9% after-hours on positive hepatitis B treatment data from imdusiran.

Arbutus Biopharma surged 15.91% in after-hours trading following the release of encouraging clinical data for its hepatitis B treatment, imdusiran. The data showed that 46% of Phase 2a patients met criteria to discontinue all treatment, and 94% of long-term follow-up patients remained treatment-free for over two years, while Phase 1b patients achieved undetectable HBV DNA levels after 18 weeks of therapy. These results, highlighted in the company’s third-quarter update, overshadowed earlier news of the European Patent Office revoking a key patent and mixed financial performance, driving investor optimism about the drug’s potential to advance toward regulatory approval.