The US Food and Drug Administration (FDA) is alerting physicians and patients that individuals undergoing treatment with immune-suppressing ofatumumab or rituximab have an increased risk of reactivating hepatitis B virus (HBV). The alerts, in the form of boxed warnings, the strongest warnings issued by the FDA, were issued September 25.
Ofatumumab, approved in 2009, is used to treat chronic lymphocytic leukemia in patients with further disease after treatment with the anticancer drugs fludarabine and alemtuzumab. Rituximab, approved in 1997, is used to treat non-Hodgkin lymphoma and chronic lymphocytic leukemia, as well as rheumatoid arthritis, granulomatosis with polyangiitis, and microscopic polyangiitis. Both drugs are classified as anti–CD20-directed monoclonal antibodies.