On September 25, 2013, the Food and Drug Administration (FDA) issued a Drug Safety Communication announcing that the FDA has approved changes to the prescribing information of the immune-suppressing and anti-cancer drugs Arzerra (ofatumumab) and Rituxan (rituximab) to add new Boxed Warning information about the risk of reactivation of hepatitis B virus (HBV) infection. The revised labels also will include additional recommendations for screening, monitoring, and managing patients on these drugs to decrease this risk. Both Arzerra and Rituxan are used to treat certain cancers of the blood and lymph system. Rituxan is also approved to treat other medical conditions, including rheumatoid arthritis. Both drugs suppress the body’s immune system.
In patients with prior HBV infection, HBV reactivation may occur when the body’s immune system is impaired. This infection can cause serious liver problems, including liver failure and death. Reactivation can occur in patients who previously had HBV infection that was clinically resolved, but who later require therapy for a condition such as cancer. When a treatment is given that can impair the body’s immune system, the previous HBV infection can again become an active infection. The initial HBV infection may occur without obvious signs of liver disease, and it may remain dormant in liver tissue. Therefore, screening for evidence of prior [HBV] exposure is necessary to reliably assess the risk of HBV reactivation.