A novel t(6;7)(p24;q21) in a chronic myelocytic leuckemia in complete cytogenetic remission after therapy with imatinib mesylate

Emergence of additional cytogenetic clones in chronic myelocytic leukemia (CML) patients who become Philadelphia chromosome-negative (Ph-) after α-interferon therapy (or more recently with imatinib mesylate) have been described. We report here a case of a novel t(6;7)(p21;q23) that developed in a CML patient in complete cytogenetic remission during imatinib therapy. In this case, fluorescence in situ hybridization and reverse transcriptase polymerase chain reaction showed a normal pattern for BCR and ABL genes, suggesting that a different and unrelated clone developed after the disappearance of the Ph chromosome. © 2004 Elsevier Inc. All rights reserved. Indications:1 patient with chronic myelocytic leukemia. Patients:1 patient, a man aged 72 years at time of diagnosis. Duration of follow-up is 28 months. TypeofStudy:Development of a novel translocation is reported in a patient with chronic myelocytic leukemia in complete cytogenetic remission during Glivec therapy. Case report. DosageDuration:400 mg daily. Duration: 28 months; therapy continues at time of report. Results:Patient achieved a complete cytogenetic response after 3 months of Glivec therapy which was maintained after 28 months of follow up. Bone marrow examination at month 28 of Glivec therapy showed the karyotype 46,XY,t(6;7)(p24;q21[2]/46,XY[20] had developed; prior to this the karyotype was 46,XY[20]. FISH analysis on this sample showed a normal 2R2G pattern of BCR/ABL signals in 300 interphase cells and in 10 metaphase cells examined. RT-PCR did not detect the BCR/ABL fusion transcript. At time of report, patient is in hematologic and cytogenetic remission; the bone marrow examination shows no sign of dysplasia. AdverseEffects:No adverse events were mentioned. AuthorsConclusions:In conclusion, it is possible that the development of Ph-clones supports a multistep model for CML transformation, but the exact meaning is still unclear, and further studies are warranted. FreeText:At presentation, hypercellular bone marrow with a variant t(9;22;19)(q34;q11;p13)[20] after cytogenetic analysis indicated a Philadelphia positive chronic myelocytic leukemia in chronic phase. A b2a2 BCR/ABL fusion transcript was detected by RT-PCR. Patient initially received hydroxyurea for 6 months, then interferon for 12 months, with no cytogenetic remission. Glivec therapy was then started. Tests: cytogenetic analysis of bone marrow aspirates, karyotype, fluorescence in situ hybridization (FISH), reverse transcriptase polymerase chain reaction (RT-PCR), Ph+ cells.