Early prediction of stable MR4.5 by depth of molecular response at 6 months in patients with chronic myeloid leukemia treated with frontline imatinib

Abstract

Treatment-free remission is achievable in approximately half of patients with chronic myeloid leukemia who attain a sustained, deep molecular response with tyrosine-kinase inhibitor (TKI) therapy. We aimed to identify potential predictors of future achievement of stable MR4.5, defined as a sustained 4.5-log reduction in BCR-ABL1 transcripts for a minimum of 2 years, in 593 patients treated with imatinib as first-line TKI therapy. In multivariable analyses of patient and disease variables including baseline blood counts, disease phase, additional cytogenetic abnormalities, prior therapy, depth and rapidity of molecular response, the only predictor for future achievement of stable MR4.5 was molecular response at 6 months. In this study, patients failing to attain a molecular response of BCR-ABL1≤ 0.16%IS after 6 months of imatinib therapy were unlikely to subsequently achieve stable MR4.5 with imatinib. Our data suggest that achievement of BCR-ABL1≤ 0.16%IS at 6 months is predictive of future stable MR4.5.