The HIV antiretrovirals Viread (tenofovir) and Emtriva (emtricitabine), which are typically combined as Truvada, can suppress hepatitis B virus (HBV) in three-quarters of those with “immune-tolerant” infection. This is a stage of the disease during which treatment usually isn't recommended, but which may represent an important window of opportunity for preventing both liver cancer and transmission of the virus.

Participants in the study had a 76 percent viral suppression rate after four years on Viread and Emtriva, which was a significantly greater rate than the 55 percent who achieved viral suppression by taking Viread by itself. However, only a few participants became “immune-active”—indicating they had the robust immune response needed to force the infection into an inactive chronic carrier state. Furthermore, those who stopped treatment saw their viral load rebound.

Hailing this as a “very important study,” Fabien Zoulim, MD, PhD, of Hôtel Dieu Hospital in Lyons, France, who was not involved in the research, notes, “Not all patients achieved viral suppression during the trial. It is therefore important to understand why—Insufficient antiviral potency? Antiviral drug resistance?—and what were the predictive factors for this failure.”

According to Zoulim, more research is needed to understand whether Truvada can indeed prevent or delay liver cancer. Note: Truvada is not FDA approved for use in people with hep B; however, physicians may still prescribe it off-label.