A novel immunotherapy, VRON-0200, is showing promise in the fight against chronic hepatitis B virus (HBV) infection. Data presented at the , 33rd Conference on Retroviruses and Opportunistic Infections (CROI) in Denver, Colorado, suggest that a single dose of VRON-0200 can reawaken the immune system’s ability to fight the virus, with sustained effects observed for up to .
Chronic HBV infection affects millions worldwide and can lead to serious liver disease, including cirrhosis and liver cancer. Current treatments, primarily antiviral medications, can suppress the virus but rarely eliminate it completely. Often, viral rebound occurs when treatment is stopped, necessitating long-term therapy. This highlights the need for therapies that can establish a “functional cure” – a state where the virus is controlled by the patient’s own immune system, even without ongoing medication.
VRON-0200, developed by Virion Therapeutics, is a first-in-class immunotherapy designed to address this challenge. It functions as a checkpoint modifier, meaning it works by releasing brakes on the immune system, allowing T cells – critical components of the immune response – to more effectively recognize and attack HBV-infected cells. The Phase 1b study results indicate that VRON-0200 can “spark” and re-awaken durable HBV-specific immunity in the majority of patients.
The data presented at CROI 2026 focused on patients with chronic HBV infection who were already receiving nucleos(t)ide antiviral therapy – standard treatment to lower viral load. A single intramuscular dose of VRON-0200 led to declines in hepatitis B surface antigen (HBsAg), a marker of active infection, that were either sustained or continued to deepen through . This suggests a lasting immune response triggered by the immunotherapy.
“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,” said Dr. Sue Currie, PhD, of Virion Therapeutics. “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.”
Importantly, VRON-0200 demonstrated a favorable safety and tolerability profile in the Phase 1b study. The drug was well-tolerated, and no serious adverse events were reported. The immunotherapy showed rapid and profound synergy when combined with agents that lower antigen levels – another strategy for controlling HBV infection.
Virion Therapeutics is building on these promising results with a Phase 2b trial, dubbed SPARK-B, which will evaluate VRON-0200 in combination with investigational antivirals. This trial will utilize a “Spark and Fan” approach, aiming to both initiate an immune response (the “Spark”) and then sustain it over time (the “Fan”).
Prior to the data presented at CROI 2026, Virion Therapeutics had already completed enrollment of the first two cohorts of its Phase 1b chronic hepatitis B trial, dosing patients with VRON-0200. These earlier cohorts evaluated both single and boosted doses of the immunotherapy. Results from these initial cohorts showed that VRON-0200 was safe and well-tolerated and capable of inducing immune responses and anti-HBV activity, even in patients with impaired HBV immunity. A third cohort, investigating VRON-0200 in combination with other anti-HBV agents, is currently underway.
Initial safety data from an earlier presentation in at the 33rd Annual Meeting of APASL (The Asian Pacific Association for the Study of the Liver) in Kyoto, Japan, showed that VRON-0200 was well-tolerated in the first chronically HBV-infected patients who received a single, low dose intramuscular injection. No serious adverse events were observed, and there were no clinically relevant abnormalities in standard laboratory tests.
While these findings are encouraging, it’s important to remember that VRON-0200 is still under investigation. The Phase 1b study was designed primarily to assess safety and initial immune responses. The Phase 2b SPARK-B trial will be crucial in determining the efficacy of VRON-0200 in achieving a functional cure for chronic HBV infection. Further research will also be needed to identify which patients are most likely to benefit from this immunotherapy and to optimize treatment regimens.
The development of VRON-0200 represents a significant step forward in the pursuit of more effective and durable treatments for chronic HBV. By harnessing the power of the immune system, this immunotherapy offers the potential to transform the lives of millions living with this challenging infection.
