The hepatitis D therapeutic landscape is experiencing unprecedented momentum with multiple breakthrough designations and promising clinical results emerging from leading pharmaceutical companies. This surge in development activity addresses a critical unmet medical need for patients with hepatitis D virus (HDV) infection, considered the most severe form of viral hepatitis.
Breakthrough Therapy Designations Signal Regulatory Confidence
In January 2025, the U.S. FDA granted Breakthrough Therapy designation to brelovitug, an investigational hepatitis D treatment developed by Bluejay Therapeutics. This designation is reserved for therapies that demonstrate significant potential in addressing serious conditions and show promising results in early clinical trials, with the aim of accelerating development and approval processes.
The regulatory momentum continued with Vir Biotechnology's experimental treatment combination receiving dual recognition. In December 2024, tobevibart and elebsiran for chronic hepatitis D received both Breakthrough Therapy designation from the U.S. FDA and PRIME designation from the European Medicines Agency (EMA).
Phase 3 Trial Demonstrates Exceptional Efficacy
Vir Biotechnology announced positive findings from the SOLSTICE Phase 2 trial in November 2024, evaluating tobevibart alone or in combination with elebsiran in individuals with chronic hepatitis delta (CHD). The investigational monoclonal antibody and siRNA combination, administered monthly, achieved a remarkable 100% virologic response with rapid suppression of hepatitis delta virus (HDV) RNA.
The trial results showed progressive improvement over time: by Week 24, 41% (13/32) of participants had HDV RNA below the lower limit of quantification (LLOQ) with target not detected (TND), increasing to 64% (14/22) by Week 36. Among participants who reached Week 60, an impressive 80% (4/5) achieved HDV RNA TND, demonstrating sustained antiviral activity.
Robust Pipeline Addresses Critical Medical Need
According to DelveInsight's assessment, the global hepatitis D pipeline constitutes over 8 key companies continuously working toward developing more than 10 hepatitis D treatment therapies. The pipeline includes companies such as Vir Biotechnology, Bluejay Therapeutics, Ribocure Pharmaceuticals AB, Assembly Biosciences, Shanghai HEP Pharmaceutical, and others.
Hepatitis D virus infection represents a serious liver condition that only occurs in individuals already infected with hepatitis B virus (HBV). The condition leads to increased chances of liver cirrhosis, liver failure, and liver cancer compared to HBV infection alone, making it a critical therapeutic target.
Diverse Therapeutic Approaches in Development
The pipeline encompasses various therapeutic modalities and mechanisms of action. Tobevibart is an investigational broadly neutralizing monoclonal antibody targeting the hepatitis B surface antigen, designed to inhibit viral entry into hepatocytes and reduce circulating viral particles. Elebsiran is an investigational siRNA designed to degrade hepatitis B virus RNA transcripts and limit hepatitis B surface antigen production.
Brelovitug represents another promising approach as a highly potent, pan-genotypic, fully human IgG1 monoclonal antibody targeting anti-HBsAg on both HDV and HBV. The drug is designed to neutralize and remove hepatitis B and hepatitis D virions while depleting HBsAg-containing subviral particles.
Clinical Trial Activity Accelerates
Recent clinical developments include Ribocure Pharmaceuticals AB's announcement in June 2025 of a clinical trial for RBD1016, a GalNAc-siRNA drug targeting the X gene of hepatitis B virus. The study will evaluate both efficacy and safety in treating chronic hepatitis D virus infection in adults, with participants randomly allocated to active treatment and deferred active groups.
Vir Biotechnology also initiated a Phase 3 clinical study in June 2025 to evaluate the efficacy and safety of tobevibart plus elebsiran combination therapy for chronic hepatitis delta compared to delayed treatment.
Market Drivers and Challenges
The hepatitis D market is being driven by rising prevalence, advancements in antiviral therapies, growing awareness and screening programs, government and non-profit support, emerging targeted therapies, and strategic collaborations and investments.
However, significant barriers remain, including limited treatment options, high therapy costs, low awareness and diagnosis rates, regulatory challenges, co-infection with HBV complications, and limited healthcare access in developing regions.
The current treatment landscape for hepatitis D virus infection remains limited, with interferon-based therapies offering only modest success rates. This limitation underscores the critical importance of the emerging pipeline therapies, which represent potential paradigm shifts in hepatitis D management and patient outcomes.
