Vir Biotechnology Reports 96-Week Phase 2 Hepatitis Delta Data for Tobevibart and Elebsiran Combination

Vir Biotechnology announced that complete 96-week data from its Phase 2 SOLSTICE clinical trial evaluating the combination of tobevibart and elebsiran in chronic hepatitis delta virus (HDV) infection will be presented at the European Association for the Study of the Liver (EASL) Congress 2026.¹

According to the company, the investigational combination demonstrated sustained virologic response rates and improvements in liver function biomarkers through nearly two years of treatment in patients with chronic HDV.¹ The findings add to growing industry efforts to develop finite and functionally curative treatment approaches for HDV, a severe form of viral hepatitis associated with accelerated liver disease progression and limited therapeutic options.²

Could combination therapy improve long-term hepatitis delta outcomes?

The SOLSTICE Phase 2 trial evaluated Vir’s dual-mechanism regimen combining tobevibart, an investigational neutralizing monoclonal antibody targeting hepatitis B surface antigen (HBsAg), with elebsiran, a small interfering RNA (siRNA) therapeutic designed to suppress HBsAg production.¹

According to the company, 100% of participants receiving the regimen achieved HDV RNA suppression below the lower limit of quantification at Week 96.¹ Investigators also reported sustained alanine aminotransferase normalization and reductions in hepatitis B surface antigen levels.¹

Vir stated that the treatment combination was generally well tolerated, with no new safety signals identified during the extended follow-up period.¹

“These complete 96-week data continue to support the potential of tobevibart and elebsiran as a combination regimen capable of delivering sustained antiviral activity in chronic hepatitis delta,” said Mark Eisner, executive vice president and chief medical officer of Vir Biotechnology, in the company’s press release.¹

HDV infection occurs only in individuals co-infected with hepatitis B virus (HBV) and is considered the most severe form of chronic viral hepatitis because of its association with rapid progression to cirrhosis, liver failure, and hepatocellular carcinoma.²

Why are functional cure strategies becoming central in hepatitis research?

The investigational regimen reflects a broader industry shift toward combination-based functional cure strategies in chronic viral hepatitis, particularly as developers pursue multi-targeted approaches for HDV infection.³

Tobevibart is designed to neutralize circulating hepatitis B surface antigen particles and potentially engage immune effector mechanisms, while elebsiran aims to reduce antigen production through RNA interference technology.^1,3

The companies developing next-generation HBV and HDV therapies are increasingly pursuing multi-targeted regimens combining siRNA agents, monoclonal antibodies, capsid inhibitors, and immune modulators.³

Vir noted that additional analyses from the SOLSTICE program presented at EASL will include long-term virologic outcomes, liver biomarker assessments, and subgroup evaluations.¹

What challenges remain in developing durable HDV therapies?

Despite recent progress in hepatitis delta research, significant unmet needs remain for patients living with chronic HDV infection. Current treatment approaches have historically been limited by modest response rates, lengthy treatment durations, and challenges maintaining long-term viral suppression.² Researchers continue to investigate whether combination regimens that target multiple stages of the viral lifecycle may offer more durable disease control while also reducing the risk of liver disease progression.

Long-term management remains especially important because chronic HDV infection is associated with rapid progression to cirrhosis, hepatic decompensation, and liver cancer.² As additional clinical data emerge, investigators will likely focus not only on virologic suppression, but also on broader clinical outcomes such as liver function improvement, fibrosis reduction, and durability of response after treatment discontinuation. The growing number of combination therapy programs entering development reflects increasing industry interest in potentially finite treatment strategies for chronic viral hepatitis.

References

1. Vir Biotechnology to Present Complete Week 96 Data from Phase 2 SOLSTICE Clinical Trial in Hepatitis Delta at the European Association for the Study of the Liver (EASL) Congress 2026. (2026 May 27). Vir Biotechnology. Accessed May 27, 2026. https://www.biospace.com/press-releases/vir-biotechnology-to-present-complete-week-96-data-from-phase-2-solstice-clinical-trial-in-hepatitis-delta-at-the-european-association-for-the-study-of-the-liver-easl-congress-2026
2. Hepatitis D Fact Sheet. (2025 Jul 25). World Health Organization. https://www.who.int/news-room/fact-sheets/detail/hepatitis-d
3. Brunetto, M. R., Ricco, G., Negro, F., et al. (2023). EASL Clinical Practice Guidelines on hepatitis delta virus. Journal of Hepatology. https://www.sciencedirect.com/science/article/pii/S0168827823003173