BCR and chronic myelogenous leukemia, BCR-ABL1 positive: Indeed, signal transduction inhibitor 571 (STI571) emerged as a fastidious BCR-ABL antagonist (Druker et al, 1996) inducing remarkable haematological and cytogenetic remissions in interferon-intolerant, -refractory or -resistant CML patients in the stable chronic phase of the disease (Druker et al, 2001).