Patterns of clonal evolution in transformed chronic myelogenous leukemia.

Chronic myelogenous leukemia (CML) is an initially indolent disease which transforms into an acute leukemia about 2-5 years after diagnosis. We report a series of 75 patients, from a total of 125 patients with CML, who underwent acute blastic transformation. These included four unclassified, 10 lymphoid, and 61 non-lymphoid acute leukemias, including 54 myeloblastic, three promyelocytic, one myelomonocytic, one erythroblastic, and two megakaryoblastic leukemias. Fifty-two patients developed new cytogenetic abnormalities in addition to being Ph positive. These included trisomies of chromosomes 8, 19, and 21, isochromosome of the long arm of chromosome 17 (i(17q)), double and triple Ph, as well as other translocations, deletions, and additions. The overall median survival once the diagnosis of acute blast crisis was made was 61 days.