Denver, CO – Virion Therapeutics today announced promising results from its Phase 1b study of VRON-0200, an immunotherapy designed to address chronic Hepatitis B virus (HBV) infection. Presented at the 33rd Conference on Retroviruses and Opportunistic Infections (CROI), the data indicate that a single intramuscular dose of VRON-0200 induced broad and sustained anti-HBV immunity in the majority of patients, with declines in Hepatitis B surface antigen (HBsAg) observed for up to 360 days.
The study, led by Dr. Sue Currie, PhD, of Virion Therapeutics, involved chronically HBV-infected patients. Results showed that VRON-0200 was able to “spark” and re-awaken durable HBV-specific immunity in these individuals. The findings also highlighted the drug’s favorable safety profile and its synergistic effect when used in combination with antiviral agents that lower antigen levels.
“We are now at a pivotal point in the development of potential functional cures for chronic HBV, with exciting progress being made, with different classes of HBV treatments,” Dr. Currie stated. “These treatments, however, are limited by their inability to restore a patient’s own immune responses against the virus. Once treatment is discontinued, viral rebound typically occurs in a large proportion of patients. The field now believes that immune modulators are necessary to mitigate this virological rebound.”
VRON-0200 is a first-in-class immunotherapy that utilizes checkpoint modifiers to address the exhaustion of HBV-specific CD8+ T cells, which limits their ability to control the virus. According to Virion Therapeutics, the drug aims to provide a functional cure for chronic HBV infection by stimulating the expansion of new functional CD8+ T cells and restoring immune control. The company notes that current antiviral therapies rarely achieve a functional cure and often require lifelong treatment.
Recent data presented at AASLD’s The Liver Meeting® 2025, as reported in November 2025, further demonstrated sustained HBsAg declines up to one year after a single VRON-0200 dose. In 83% of patients (19 out of 23), the drug induced anti-HBV immune activation and restoration, with HBsAg declines beginning as early as Day 28. A combination of VRON-0200 with investigational antivirals resulted in rapid and profound HBsAg declines in all patients tested (n=7), with complete HBsAg loss observed in three of six patients at Week 20.
Virion Therapeutics describes a “Spark and Fan” model, where VRON-0200 acts as an initial “spark” to prime the anti-HBV immune response, which is then “fanned” or boosted by antiviral regimens that reduce the viral load. The company believes this approach has the potential to prevent the need for rescue medications after HBV treatment discontinuation and improve overall functional cure rates.
The Phase 1b study reported no serious treatment-related adverse events, treatment discontinuations, or clinical laboratory abnormalities. Virion Therapeutics is currently evaluating the potential of VRON-0200 as a key component in combination HBV functional cure regimens.
