Chronic Myeloid Leukemia: Long-Term Experience of Target Therapy

Background & Aims. Interpretation of key aspects of pathogenesis of chronic myeloid leukemia (CML) and development and introduction of target therapy have changed the prognosis of this once fatal disease dramatically. Results of numerous clinical trials demonstrated substantial superiority of tyrosine kinase inhibitors over previous therapy techniques. At the same time, clinical trials had limitations in patient enrollment, as well as treatment conditions and duration. The analysis of our clinical experience in CML target therapy (over the period from 2003 till 2015) is an important argument for introduction of novel drugs into routine clinical practice. The aim of the study is to analyze our own experience in CML target therapy and to compare our results with clinical trials data. Methods. Outpatient’s cards and case histories of CML patients treated in the Russian Scientific Research Institute of Hematology and Transfusiology over last 12 years were analyzed in this work. Published results of multi-center clinical trials evaluating the use of tyrosine kinase inhibitors in CML were used for a comparative analysis. The primary morbidity rate and the prevalence of CML, results of first and subsequent treatment lines were studied with assessment of survival rates, adverse events, and the nature of the response (hematologic, cytogenetic and molecular). Results. The experience in treatment of 208 CML patients was analyzed. The use of imatinib led to clinical and hematological remission (complete hematologic response) was achieved in 95 % of patients. The frequency of complete cytogenetic responses (CCyR) was 69 %, and that of major molecular responses (MMR) was 58 %. The overall 5-year survival (OS) was 86.4 %, the 10-years OS was 67.5 %. The use of nilotinib during the second line permitted to achieve CCyR in 61 % of patients, and the MMR in 55 % of cases. The two-year OS was 96 % and the 5-year OS was 68 %. CCyR and MMR were achieved in 50 % patients treated with dasatinib during the second line. As for the third line, CCyR was achieved in 50 % of patients and MMR in 25 %. In case of previous imatinib and nilotinib resistance, CCyR was observed only in 36 % of patients and MMR in 18 % of cases. During second-line dasatinib treatment, the 2-year OS was 85 %, and the 5-year OS was 51 %; as for the third line, the results were 75 % and 50 %, respectively. The range and rates of adverse events of the therapy, in general, corresponded to results of clinical trials. Conclusion. The use of tyrosine kinase inhibitors in treatment of CML permits to prolong patient’s life span and quality of life significantly. The use of nilotinib and dazatinib (in case of nilotinib intolerance and/or resistance) could be effective in most patients