The US Food and Drug Administration today issued a new black-box warning for the immunosuppressant rituximab (Rituxan), boosting the level of vigilance for the risk of liver damage and death due to reactivation of prior hepatitis B infection among patients taking the drug. Rituximab is approved for rheumatologic conditions such as rheumatoid arthritis and vasculitis as well as for forms of lymphoma.
The Agency has also revised its guidance to doctors issuing new prescriptions for rituximab, recommending that they:
• Screen all patients by hepatitis B surface antigen (HBsAg) and hepatitis B core antibody (anti-HBc) before prescribing rituximab.
• When screening identifies evidence of prior HBV infection, consult with hepatitis experts about monitoring and use of HBV antiviral therapy.
• Monitor patients with evidence of prior HBV infection for clinical and laboratory signs of hepatitis B or HBV reactivation during rituximab treatment and for several months after it is withdrawn. Reactivations have occurred after completion of therapy, the FDA reports.
• Immediately discontinue the drug if reactivation of HBV develops. The advisory says there is insufficient data to make any recommendation about resuming the drug for patients with hepatitis due to HBV reactivation after that condition is resolved.
The FDA warning also applies to the anti-cancer agent ofatumumab (Arzerra).
Both drugs are monoclonal antibodies that target the B-lymphocyte antigen CD20. Although a warning about the risk of HBV reactivation already existed on product packing, the FDA decided to strengthen the warning because cases of reactivation continued to arise.