Emergence of clonal chromosomal abnormalities in Philadelphia negative hematopoiesis in chronic myeloid leukemia patients treated with nilotinib after failure of imatinib therapy

Clonal cytogenetic abnormalities (CAs) in Philadelphia negative (Ph−) metaphases have been widely observed during imatinib treatment in patients with chronic myeloid leukemia (CML) [1,2]. Recently, the appearance of such abnormalities in some CML patients, treated with dasatinib after imatinib failure, has been described [3,4]. To the best of our knowledge, only one patient has been reported to develop a cytogenetic abnormality in Ph− clone during nilotinib treatment, following imatinib [5]. The incidence and consequences of CAs in Ph− cells during treatment with second generation tyrosine kinase inhibitors (TKIs) should be extensively investigated; this issue, deserves a particular attention, since these new drugs put a far higher pressure on the leukemic and the residual normal hematopoiesis than imatinib.