Gilead Sciences turned its Foster City campus into celebration mode last Friday, after the FDA cleared Hepcludex as the first U.S. treatment for chronic hepatitis D. The decision hands physicians a long-awaited, regulated option for a hard-to-treat, fast-moving liver infection just as two Bay Area biotechs push their own candidates toward late-stage readouts. For local researchers and patient groups, the approval opens new clinical pathways even as it sharpens questions about access, safety monitoring and how fierce the coming competition will get.
According to the U.S. Food and Drug Administration, the agency granted accelerated approval to Hepcludex (bulevirtide-gmod) last Friday, for adults with chronic HDV who do not have decompensated cirrhosis. The FDA cited MYR301 Phase 3 data showing a combined virologic and biochemical response of roughly 48% at week 48 and cautioned that stopping therapy can trigger severe hepatitis B and D flares.
Gilead is pitching the clearance as a milestone for an underserved patient population and says it will continue to run confirmatory studies while helping clinicians navigate coverage and access through company support programs. Gilead notes that Hepcludex is supplied as a once daily subcutaneous injection and that continued approval may hinge on longer-term outcome data.
Bay Area Rivals Line Up Their Own HDV Shots
Close behind, Foster City-based Mirum Pharmaceuticals reported that its monoclonal antibody brelovitug hit the primary endpoint in the Phase 2b portion of AZURE-1, showing strong virologic responses and ALT normalization that the company plans to present at EASL. Mirum says topline Phase 3 results for AZURE-1 and AZURE-4 are expected later this year.
San Francisco's Vir Biotechnology is also moving forward. The company says its SOLSTICE Phase 2 combination of tobevibart plus elebsiran produced high rates of viral suppression in longer follow-up and will present Week 96 data at EASL later this month. Vir Biotechnology reported that 77% of participants had an HDV RNA target not detected status by Week 72 and that a Week 96 subset showed an 88% rate.
The FDA's accelerated pathway shortens the time to availability but demands confirmatory evidence of clinical benefit, and industry watchers say the Hepcludex decision shifts the question from whether a U.S. therapy will exist to how fast competitors can match or beat its results. The agency approved Hepcludex on virologic and biochemical endpoints, and Gilead has committed to longer-term studies.
Estimates of the U.S. HDV population vary, but statements from both regulators and drugmakers place the figure in the tens of thousands, roughly 40,000 to 80,000 people, making the market small but clinically urgent. The U.S. Food and Drug Administration emphasizes close HBV co-management and post-treatment monitoring because abrupt discontinuation can provoke severe flares.
What To Watch Next
Investors, hepatologists and patient advocates will be watching pricing, insurance coverage and how quickly clinics embrace a daily injectable that comes with boxed warning guidance, while Mirum and Vir press toward registrational readouts that could reset standards of care. As the San Francisco Business Times reported, the Bay Area, home to Gilead, Mirum and Vir, may turn into the epicenter of HDV drug development over the coming year.
