OBJECTIVETo investigate cytogenetic features and outcome of chromosomal abnormalities in Philadelphia negative cells (Ph(-)CAs) of chronic myelogenous leukemia (CML) patients treated with tyrosine kinase inhibitors.

METHODSClinical and laboratory data of 15 CML patients in which Ph(-)CAs occurred after tyrosine kinase inhibitors therapy were collected and analyzed.

RESULTSOf 15 cases with Ph(-)CAs, 12 patients were treated with imatinib, 2 were treated with dasatinib and 1 was treated with bosutinib. + 8 was the most common abnormality in Ph(-)CAs, which accounted for 46.7% of all. Ph(-)CAs usually occurred when Ph(+)cells decreased or disappeared due to tyrosine kinase inhibitors therapy. The average time for the appearance of Ph(-)CAs was 11.1 months (1-28 months). In 7 patients, the Ph(-)CAs have disappeared in 10.9 months (3-24 months). In such patients, no myelodysplastic syndrome or acute leukemia was observed. One patient has progressed to acute monocytic leukemia with Ph(+)cells. All remaining patients have achieved bone morrow remission, among which 11 patients achieved complete cytogenic response and 4 patients even achieved complete molecular response.

CONCLUSIONThe majority of Ph(-)CAs developed in CML patients are transient in nature. They may develop following imatinib, dasatinib or bosutinib therapy but do not interfere with the therapeutic effects of tyrosine kinase inhibitors.