Follow-up of the Persistence of the Complete Molecular Remission After Stopping Imatinib Chronic Myeloid Leukemia

Chronic myeloid leukemia (CML) is an hematopoietic stem cell disorder in which a t (9;22) (q34;q11) reciprocal chromosomal translocation gives rise to Philadelphia chromosome (Ph) and generates the BCR-ABL1 fusion gene encoding a constitutively activated protein tyrosine kinases (PTK). Tyrosine kinase Inibitors (TKIs) such as imatinib, by blocking BCR-ABL1 kinase activity, selectively eradicate CML cells and induce durable responses and prolong survival. CML patients treated with TKI are monitored by BCR-ABL1 RT-qPCR (Reverse Transcription real-time quantitative Polymerase Chain Reaction) performed from peripheral blood samples. A first multicenter study entitled STIM trial demonstrated that imatinib could be safely discontinued in patients with complete molecular remission (CMR) for at least 2 years (undetectable BCR-ABL1 transcript by RT-qPCR). Around 40% of these patients remain in a prolonged treatment-free remission (TFR) after treatment cessation. All molecular relapsing patients were sensitive when imatinib was re-challenged. The purpose of this STIM-FU study is to follow all the patients included in the STIM trial in order to evaluate their molecular status, vital status and ongoing treatment in patient with a first molecular relapse. This long term follow up will allow us to predict if a constant long term control of the disease is possible and to better define the clinical and biological CML-related factors predictive for a molecular relapse after TKI discontinuation.