Predictive Factors for Molecular Response in Chronic Myeloid Leukemia: Reduction Ratio and Halving Time of IS Transcript Levels.

OBJECTIVE

Achieving an early molecular response (EMR) is crucial for improving the prognosis of patients with chronic myeloid leukemia (CML). The halving time (HT) and reduction ratio (RR) of transcript levels have recently emerged as additional prognostic indexes besides the International Scale (IS). We aimed to investigate the prognostic role of transcript levels, HT, and RR on molecular response kinetics at 3 months in patients with newly diagnosed chronic-phase (CP)-CML.

MATERIALS AND METHODS

Forty patients with CP-CML who received first-line imatinib treatment were included in this study. transcript levels and molecular responses at baseline and at 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.

RESULTS

Of the 40 patients, IS was ≤10% at 3 months in 72.5%, representing EMR. The rate of event occurrence was 45.5% in patients with IS of >10%, whereas it was 6.9% in those with IS of ≤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 of ≤24 days and RR of ≤0.04. EFS was found to be significantly better in the group with IS of ≤10% and HT of ≤24 days (p=0.001) and in the group with IS of ≤10% and RR of ≤0.04 (p=0.007) compared to others.

CONCLUSION

Our findings revealed that MMR could be predicted via EMR as well as by HT and RR. Additionally, HT of ≤24 days and RR of ≤0.04 were more important than IS of ≤10% in achieving DMR at 24 months, and the combination of IS of ≤10% with both HT of ≤24 days and RR of ≤0.04 has the best predictive value for EFS.