Gilead Sciences, Inc. and Vir Biotechnology, Inc. announced that the companies have entered into a clinical collaboration to evaluate novel therapeutic combination strategies aimed at developing a functional cure for chronic hepatitis B virus (HBV). The companies plan to initiate a Phase 2 trial evaluating combination therapy for both treatment-experienced and treatment-naïve people living with HBV. The multi-arm trial will evaluate different combinations of selgantolimod, Gilead's investigational TLR-8 agonist; VIR-2218, Vir's investigational small interfering ribonucleic acid (siRNA); and a commercially-sourced, marketed PD-1 antagonist.

People in the trial with HBV treatment experience may also receive Gilead's Vemlidy (tenofovir alafenamide fumarate, TAF). The primary outcome of the study will be the proportion of patients achieving a functional cure, defined as an off-therapy loss of hepatitis B surface antigen (HBsAg) and HBV DNA from the serum. Both companies retain full rights to their individual product candidates and will discuss the potential path forward for any future combination studies based on the outcome of the Phase 2 trial.

HBV affects more than 290 million people worldwide. Globally, HBV is a leading cause of liver cancer and each year it is estimated that more than 800,000 people die of HBV-related liver disease. While current antiviral therapies result in sustained HBV viral suppression, they rarely completely clear the virus and therefore people with HBV require lifelong therapy.

The safety and efficacy of selgantolimod and VIR-2218 have not been established. They are investigational compounds, not approved by the U.S. Food and Drug Administration (FDA) or any other regulatory authority.