In-depth characterization of NK cell markers from CML patients who discontinued tyrosine kinase inhibitor therapy

Introduction Treatment-free remission (TFR) in patients with chronic myeloid leukemia phase is considered a safe option if suitable molecular monitoring available. However, the question arises as to which factors can contribute maintenance of TFR, and immunologic surveillance remaining leukemic cells believed be one them. Argentina Stop Trial an open-label, single-arm, multicenter trial assessing TFR after tyrosine kinase inhibitors interruption, that more than 4 years showed successful rate 63%. Methods In this context, we set up immunological study by flow cytometry order analyze specific NK cell subsets from peripheral blood patient samples both at time discontinuation well during subsequent months. Results At discontinuation, show mature phenotype, probably associated TKI treatment. 3 months significant changes several receptors occurred. Patients higher proportion CD56dim PD-1+ better chances survival. More interestingly, non-relapsing also presented subpopulation features expansion cytomegalovirus infection (expression CD57+NKG2C+), NKp30 NKp46 natural cytotoxicity receptors, resulted greater degranulation survival (p<0.0001). Discussion This subset could have protective role who do not relapse, thus further characterization useful for sustained deep response.