Gilead Sciences Inc (NASDAQ:GILD) saw its stock climb 2.5% on Friday after the U.S. Food and Drug Administration approved Hepcludex (bulevirtide-gmod) injection for the treatment of chronic hepatitis delta virus infection in adults without cirrhosis or those with compensated cirrhosis.
Bulevirtide is the first therapy to receive FDA approval specifically for chronic HDV infection. HDV is a serious viral illness that can accelerate liver damage, potentially leading to rapid progression of fibrosis, liver cancer, liver failure, and death. The infection only appears in individuals who are also infected with hepatitis B virus.
The FDA approval is supported by results from a multicenter, randomized, open-label, parallel-arm phase 3 clinical trial, designated Trial MYR301. In that study, participants were randomized to either immediate treatment with Hepcludex 8.5 mg once daily for a planned 144 weeks or to a delayed-treatment arm consisting of a 48-week observational period followed by Hepcludex 8.5 mg once daily for 96 weeks.
The trial's primary efficacy endpoint was a combined response assessed at week 48. That combined response required either undetectable HDV RNA or at least a 2 log10 IU/mL decline from baseline, together with normalization of aminotransferase levels. At week 48, the combined response rate was 48% in the group receiving Hepcludex immediately compared with 2% in the delayed-treatment group.
Key virologic outcomes included the rate of undetectable HDV RNA. At week 48, 20% of patients in the Hepcludex arm had undetectable HDV RNA versus 0% in the delayed group. Continued treatment was associated with higher rates of undetectable HDV RNA over time, with 36% of Hepcludex-treated patients reaching undetectable levels by week 96 and 50% by week 144.
Safety information in the prescribing label lists possible adverse reactions such as hypersensitivity reactions, including anaphylaxis, injection site reactions, headache, abdominal pain, fatigue, and pruritus. The label also contains a boxed warning noting that discontinuation of Hepcludex may result in severe acute exacerbations of both HDV and hepatitis B virus infections.
Regulatory designations granted to Hepcludex included Breakthrough Therapy Designation and Orphan-Drug Designation from the FDA. The application underwent priority review and the approval was granted under the Accelerated Approval pathway.
This report summarizes the regulatory decision, the clinical trial evidence cited in the approval, and the safety information included in the product labeling.