Cytogenetic evolution in two Ph⁺ chronic myeloproliferative disorders patients during treatment with imatinib

The Philadelphia (Ph) chromosome is the typical cytogenetic abnormality of chronic myeloid leukaemia (CML). Imatinib mesilate (IM) is a new drug which inhibits the tyrosine kinase, the product of the fusion gene, bcr-abl, on Ph chromosome. So, by inhibiting the tyrosine kinase, the expansion of the myeloid lineage is stopped. Cytogenetetic evolution occurs either during disease progression or during treatment of CML. Lately, more multiple complex chromosomal changes, which are untypical for known CML cytogenetic evolution, were linked to IM treatment. We describe two more cases.