Gilead’s Hepcludex (bulevirtide-gmod) cleared the FDA on May 22, landing accelerated approval under 21 CFR 601.41 as the first treatment for chronic hepatitis delta virus in the US. The Phase 3 MYR301 trial showed 48% of patients hit a combined virologic and biochemical response at Week 48, against 2% in the delayed-treatment arm.
That efficacy gap doesn’t explain the four-year gap in US approval. Gilead received a Complete Response Letter in October 2022, citing manufacturing and product delivery concerns only, with no new clinical data requested. The EU had greenlit bulevirtide under the same brand in 2020, six years before US patients got access.
HDV infects only people with active hepatitis B; FDA estimates 40,000 to 80,000 Americans carry it. With no US competition in the indication, Gilead sets both the floor and the ceiling.
Approval comes under the accelerated pathway, tied to surrogate endpoints (HDV RNA reduction and ALT normalization), so continued marketing depends on a confirmatory trial establishing clinical benefit. The label carries a boxed warning: discontinuation can trigger severe acute exacerbations of both HDV and hepatitis B.
I read the MYR301 protocol this week. It’s the 96-week off-treatment follow-up built into the design that’ll determine whether accelerated converts to standard. Worth watching when Gilead submits those data.
Rebecca Lauren