BCR and chronic myelogenous leukemia, BCR-ABL1 positive: However, cancer researchers clearly recognise the importance of these events, especially as they led to the development of two early successfully targeted cancer therapies, Herceptin (Genentech, Inc, South San Francisco, CA, USA) (based initially on amplification of ERBB2 in breast cancer) (Park et al, 2008) and Gleevec (Druker, 2008), based on BCR–ABL translocation in chronic myelogenous leukaemia.