[Halving Time of BCR-ABL Transcripts as a Precise Predictor for Deep Molecular Response in Patients with Chronic Myeloid Leukemia Treated with TKI].

Objective: To investigate the early predictive value of halving time (HT) of BCR-ABL^IS for deep molecular response (DMR) in patients with chronic myeloid leukemia (CML) treated with tyrosine kinase inhibitor (TKI).

Methods: The continuous data of newly diagnosed CML patients with complete case data and first-line imatinib treatment admitted to the Affiliated Hospital of Inner Mongolia Medical University from January 2014 to June 2022 were retrospectively analyzed. Combined with the clinical characteristics of the patients and the efficacy analysis at each time point, a logistic regression model was used to explore the independent influencing factors of DMR, and combined HT of BCR-ABL^IS with BCR-ABL^IS level at 3 months to predict DMR of the patients.

Results: Univariate and multivariate analyses showed that HT and 3-month BCR-ABL^IS levels were independent influencing factors for MR4, MR4.5, and stable MR4.5 ( P < 0.05). ROC curve analysis determined that the best cut-off value of HT was 28 days. Compared with patients with HT>28 d, patients with HT≤28 d were more likely to obtain DMR at 2, 3, and 5 years, respectively (74.2% vs 27.3%, 71.2% vs 22.7%, and 63.6% vs 25.0%, all P < 0.001). The patients were divided into 4 groups according to BCR-ABL^IS levels at 3 months and HT. Kaplan-Meier analysis showed that the patients in the BCR-ABL^IS≤10% and HT≤28 d group had a higher probability of obtaining cumulative MR4 and MR4.5 than those in the BCR-ABL^IS≤10% and HT>28 d group (P < ＜0.05); Patients in the BCR-ABL^IS>10% and HT≤28 d group had a higher probability of obtaining cumulative MR4 and MR4.5 than those in the BCR-ABL^IS＞10% and HT>28 d group ( P < 0.05).

Conclusion: In addition to BCR-ABL^IS level, HT of BCR-ABL^IS can be used as another important predictor of treatment efficacy in CML patients. The combination of BCR-ABL^IS level and HT has a more accurate predictive value for long-term molecular response of CML patients after TKI treatment.