Vir pressures Gilead with hepatitis D cocktail showing early efficacy in phase 2

Vir Biotechnology's hepatitis D combination therapy has shown early efficacy in results from a phase 2 trial, suggesting the drug cocktail may pose a threat to Gilead Sciences' stuttering attempt to capture the market.

Hepatitis D can only infect people if the hepatitis B virus is present. Compared to people with hepatitis B alone, people living with both viruses have a higher risk of irreversible liver damage and life-threatening complications. No treatments are approved in the U.S. Vir wants to change that with a drug combination designed to inhibit viral entry, neutralize virus particles and otherwise impede the pathogens.

Vir shared early evidence it is on the right track Wednesday. The first six participants received tobevibart or elebsiran, the hepatitis D candidates, as a monotherapy before starting combination treatment. Two of the five people who spent 48 weeks on combination therapy met a combined endpoint that looked for signs of efficacy including undetectable hepatitis D RNA and normal levels of a liver damage marker.

The biotech also shared data on 27 patients who started on the monthly drug combination. Twelve of the patients met the combined endpoint after 12 weeks of treatment. Vir only has 24-week data on 11 participants in the de novo combination cohort. The response rate was higher at 24 weeks, when seven of the subjects met the criteria. 

Vir saw similar response rates in patients who received tobevibart as a single agent. Fewer people on the monotherapy met the threshold for virologic response, but the effect on the liver damage marker was as good as in the combination arm, resulting in similar figures on the combined endpoint.

The results suggest Vir may have an edge over Gilead’s bulevirtide, which has not been shown to lead to hepatitis D clearance and is injected daily. The next clinical trial could more clearly show how the rival treatments compare, as Carey Hwang, M.D., Ph.D., senior vice president of clinical research at Vir, said on a conference call with investors to discuss the data. 

“We are eager to engage with regulatory authorities in Q3 of this year to discuss the next steps for the development program. We anticipate that the next trial will use bulevirtide as comparator, and we look forward to aligning the clinical development plan with health authorities. Additionally, we will explore all available acceleration pathways,” Hwang said.

However fast Vir moves, Gilead could still get to the U.S. market first. The FDA knocked back a request for approval of bulevirtide in 2022, but Gilead has submitted a filing intended to fix the manufacturing and delivery concerns raised in the complete response letter. Bulevirtide, which Gilead acquired in its MYR acquisition, is already available in Europe.