Sudden blast crisis in a chronic myeloid leukemia patient during imatinib therapy

Imatinib mesilate (IM) is the first line therapy for chronic myeloid leukemia (CML) patients in chronic phase. Although it offers a complete cytogenetic response (CCyR) in a majority of patients, there still are some rare cases in which a sudden blast crisis (SBC) evolves. The mechanism of this unexpected event is not yet completely understood. We present the case of a female patient who developed a SBC while being under IM therapy. We do not know for sure which is the role of IM in this event, but current available data suggest that this drug may have a permissive effect on the evolution of some aggressive subclones in the context of restored normal cell population.