Predictive Factors for Molecular Response in Chronic Myeloid Leukemia: Reduction Ratio and Halving time of BCR::ABL1 IS Transcript Levels

• Published in: Turkish journal of haematology Vol. 39; no. 3; pp. 196 - 203
• Main Authors: Ceran, Funda, Akıncı, Sema, Uçar, Mehmet Ali, Korkmaz, Gülten, Gündüz, Mehmet, Çavdarlı, Büşranur, Bakanay, Şule Mine, Falay, Mesude, Dağdaş, Simten, Dilek, İmdat, Özet, Gülsüm
• Format: Journal Article
• Language: English
• Published: Turkey Galenos Publishing 25.08.2022
• Subjects: BCR:ABL1 IS; Chronic Myeloid Leukemia; Reduction Ratio; Halving Time; Molecular Response
• ISSN: 1300-7777; 1308-5263
• DOI: 10.4274/tjh.galenos.2022.2022-0024

Achieving an early molecular response (EMR) is crucial for improving the prognosis of patients with chronic myeloid leukemia (CML). Halving time (HT) and reduction ratio (RR) of BCR::ABL1 transcript levels have recently emerged as additional prognostic indexes to BCR::ABL1 International Scale (IS). We aimed to investigate the prognostic role of BCR::ABL1 transcript levels, HT and RR on molecular response kinetics at 3 months in patients with newly diagnosed chronic phase (CP)-CML. Forty patients with CP-CML who received first-line imatinib treatment were included in this study. BCR::ABL1 transcript levels and molecular responses at baseline, 3, 6, 12 and 24 months of treatment were evaluated retrospectively. Major molecular response(MMR) at 12 months and event-free survival (EFS) were determined as primary endpoints and the effects of treatment kinetics on these parameters were examined. Of the 40 patients, BCR::ABL1 IS was ≤10% at 3 months (EMR) in 72.5%. The event occurrence was 45.5% in patients with BCR::ABL1 IS>10%, whereas 6.9% in those with ≤10% (p=0.004). MMR was detected in 62.1% of the patients with EMR and in 9.1% of those without EMR (p=0.003). The cut-off value for achieving MMR was 24 days for HT and 0.04 for RR. Deep molecular response (DMR) at 24 months was associated with HT≤24 days and RR≤0.04. EFS was found to be significantly better in the group with BCR::ABL1 IS≤10% and HT≤24 days (p=0.001) and in the group with BCR::ABL1 IS ≤10% and RR≤0.04 (p=0.007) than the other groups. Our findings revealed that MMR could be predicted via EMR as well as by HT and RR. Also, HT≤24 days and RR≤0.04 were more important than BCR::ABL1 IS≤10% in achieving DMR at 24 months, and the combination of BCR::ABL1 IS≤10% with both HT≤24 days and RR≤0.04 has the best predictive value for EFS.