This study aimed to validate previously associated major histocompatibility complex ( MHC ) variants as predictors of risk of liver injury by using a large , randomized , placebo-controlled trial of lapatinib in human epidermal growth factor receptor 2-positive , early-stage breast cancer ( Tykerb Evaluation After Chemotherapy [ TEACH ] : Lapatinib Versus Placebo In Women With Early-Stage Breast Cancer ) .