A phase II trial assessing the efficacy and safety of afatinib in extensively pretreated patients with HER2/neu-negative MBC found that afatinib had limited activity in HER2/neu-negative breast cancer (Schuler et al., 2012).Another phase II trial evaluated afatinib monotherapy in patients with HER2/neu-positive MBC after failure oftrastuzumab treatment. This evidence concerns the gene ERBB2 and breast cancer.