Trastuzumab, an anti-HER2 monoclonal antibody, and imatinib, a small molecule tyrosine kinase inhibitor targeting the BCR-ABL fusion-mediated aberrantly activated ABL kinase, were developed and clinically approved in 1998 and 2001 for treatment of HER2-positive breast cancer and Philadelphia chromosome-positive chronic myelogenous leukemia, respectively14,17–19. This evidence concerns the gene BCR and chronic myelogenous leukemia, BCR-ABL1 positive.