Increased tumor burden in patients with chronic myeloid leukemia after 36 months of imatinib discontinuation

TO THE EDITOR: The Imatinib Suspension and Validation (ISAV) study1 is a multicenter trial of imatinib discontinuation (ID) among patients with chronic myeloid leukemia (CML) in undetectable deep molecular remission (U-DMR). After 12 months of follow-up, 48% of patients relapsed (total n = 107), with the majority of relapses occurring within the first 9 months. An inverse relationship between patient age and risk of relapse was also observed at this timepoint. Here we report the final results of ISAV after a median follow-up of 49 months, as well as the dynamics of leukemic tumor load as determined by digital polymerase chain reaction (dPCR) in nonrelapsed patients. This trial is registered at www.clinicaltrials.gov (NCT01578213). Eligible patients were 18 years and older and had CML, either in chronic or accelerated phase, with U-DMR of at least 18 months’ duration and at least...