Arbutus Biopharma Secures FDA Fast Track for Imdusiran After 10 HBV Functional Cures
The FDA granted Fast Track designation to Arbutus’s RNAi candidate imdusiran for chronic hepatitis B, enabling earlier meetings, rolling review, and potential accelerated approval. Phase 2a trials reported 10 functional cures and 41 patients off nucleos(t)ide analogues for over 48 weeks, with two additional long-term follow-up cures, underscoring imdusiran’s durability.
1. FDA Fast Track Designation
Arbutus’s investigational RNAi therapy imdusiran has been granted Fast Track status by the FDA for chronic hepatitis B, a designation intended to expedite the drug’s development and review. This status allows for more frequent interactions with regulators and potential eligibility for accelerated approval pathways.
2. Phase 2a Trial Outcomes
In Phase 2a studies, imdusiran achieved functional cure in 10 patients and enabled 41 individuals to discontinue nucleos(t)ide analogue therapy for at least 48 weeks. Two additional participants in long-term follow-up also reached sustained cure benchmarks, defined by HBsAg seroclearance and undetectable HBV DNA.
3. Durability and Safety Profile
Clinical data indicate imdusiran is generally safe and well-tolerated, with meaningful reductions in hepatitis B surface antigen and viral DNA. The durability of these responses over two years suggests a potentially transformative treatment for the estimated 250 million people living with chronic hepatitis B worldwide.
4. Regulatory and Commercial Outlook
Fast Track designation could shorten the pathway to market by enabling rolling submission of data and priority review of a Biologics License Application. Successful acceleration of imdusiran’s approval would position Arbutus to capture significant market share in a space with substantial unmet medical need.