Sept 25 (Reuters) - U.S. regulators strengthened the warninglabels on two cancer drugs - GlaxoSmithKline Plc's Arzerra, and Rituxan, made by Biogen Idec Inc and RocheHolding AG - to reflect the risk that they canreactivate the hepatitis B virus in patients previously infectedwith it.
The U.S. Food and Drug Administration said the risk isalready described in the warnings and precautions section of thelabel for both drugs. Now the information will be placed in ablack box, indicating the most serious type of risk.