Prevention of HBV reactivation in patients treated with biologic agents.

Owing to the sensitive equilibrium between the hepatitis B virus (HBV) and the host's immune system in infected and exposed individuals, the immunosuppression caused by biologic treatment has been strongly linked to HBV reactivation (HBVr). HBVr in the setting of biologic therapy is a cause of considerable morbidity, hospitalization, interruption of treatment and mortality. However, recent literature has established that this is a largely preventable problem. Thus, it is essential for clinicians using biologic agents to be aware of HBVr potential and screen all susceptible patients. The risk for HBVr may vary depending on the host's HBV infection status and the potency of immunosuppression. The appropriate pre-emptive antiviral prophylaxis or monitoring for individuals at risk is emphasized in the latest evidence-based guidelines, but a number of unanswered questions remain.