Are the Secondary Chromosome Abnormalities Seen in Chronic Myeloid Leukemia (CML) Cells Induced to Ph-Chromosome Negativity by Imatinib a Result of Chromosome Instability or a Side Effect of the Therapy - a Study in GIST (Gastrointestinal Stromal Cell Tumors) Patients Treated With Imatinib.

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by the presence of the Philadelphia (Ph) chromosome - a t(9:22) translocation that results in the production of a BCR/ABL fusion protein with Abl kinase activity.

Imatinib mesylate (Gleevec) specifically targets a limited set of protein tyrosine kinases - ABL, Arg (Abl-related gene), c-Kit, platelet-derived growth factor receptor (PDGF-R) - and their oncogenic forms, most notably BCR/ABL Imatinib is also a potent inhibitor of a receptor-type c-Kit tyrosine kinase. Therefore imatinib was examined for therapeutic efficacy against malignant gastro-intestinal stromal tumors (GIST) Recent articles have drawn attention to the development of new Ph-negative, cytogenetically unrelated clones after therapy of Ph-positive CML with imatinib. Trisomy 8 and monosomy 7 are the most frequent defects, but other aberrations have also been reported. Some of these cytogenetic abnormalities are associated with acute myeloid leukemia and MDS.