Safety labeling revision for GlaxoSmithKline’s Tykerb (lapatinib tablets) that includes a boxed warning about the risk of hepatotoxicity has been approved by the U.S. Food and Drug Administration. Hepatotoxicity cases have been reported during clinical trials, some of them being severe. The FDA has noted that the onset of the disease has taken place within a few months from initiation of the therapy. Tests for liver functioning should be taken before starting and during lapatinib treatment, every month. Lapatinib is a kinase inhibitor to be used along with capecitabine in the treatment of advanced breast cancer in patients who did not benefit from a therapy earlier.