An Observational Study for CML Patients Who Discontinued Tyrosine Kinase Inhibitors Intentionally After Achieving a Deep Molecular Response

Treatment of Chronic Myeloid Leukemia (CML) has been revolutionized by the use of tyrosine kinase inhibitors including imatinib mesylate (Gleevec, Novartis Laboratories). Two other inhibitors of the BCR-ABL kinase are currently on the market in France, nilotinib (Tasigna®, Novartis Laboratories) in the first and second-line treatment and dasatinib (SPRYCEL®, Bristol-Myers Squibb Laboratories) in second line. Achieving a complete molecular response (CMR) in patients with Chronic Myeloid Leukemia (CML) treated with tyrosine kinase inhibitors may be currently regarded as the ultimate level of reduction of residual disease. The pilot Stop Imatinib study has opened the way for a french prospective study of stopping imatinib, the STIM study. The results of the STIM study showed that almost 60% of patients exhibited molecular relapse, most frequently within the first 6 months after discontinuation. The parameters that are statistically associated with the loss of complete molecular response are the Sokal score at diagnosis and the total duration of treatment with imatinib. Criteria to define molecular relapse in treatment free remission patients are not well defined and validated. The aim of the study is to validate the loss of major molecular response as a robust criteria for TKI resumption. The patient's population will be CML patients who are offered to discontinue therapy outside the STIM strial.