[Comparative analysis of long-term efficacy between the CCCG-ALL-2015 and CCLG-ALL-2008 protocols in adolescents with...

Objective: To compare the long-term efficacy and safety of the CCCG-ALL-2015 and CCLG-ALL-2008 protocols in treating adolescents and older children (aged ≥10 years) with acute lymphoblastic leukemia (ALL) and explore the key factors affecting prognosis. Methods: A retrospective analysis was conducted on the clinical data of patients aged 10-18 years who were admitted to the Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences between January 2008 and October 2020. The patients were treated with either the CCCG-ALL-2015 (Group Ⅰ) protocol or the CCLG-ALL-2008 (Group Ⅱ) protocol. The Kaplan-Meier analysis was used to evaluate the overall survival (OS) and event-free survival (EFS) rates, and for univariate analysis. Multivariate analysis was performed using the Cox proportional-hazards regression model. Results: Altogether, 355 patients were enrolled, including 210 in Group Ⅰ and 145 in Group Ⅱ. There were 214 men and 141 women; 286 and 69 had B-ALL and T-ALL, respectively. The complete remission rate after induction therapy in Group Ⅰ was 99.5%, which was higher than the in Group Ⅱ at 91.7% (P<0.001, χ(2)=14.596). The median follow-up time was 84 (range: 2-206) months. A total of 89 patients (25.1%) relapsed, and 73 (20.6%) died. The predicted 10-year EFS and OS rates for all 355 patients were (65.9 ± 2.6) % and (79.1 ± 2.2) %, respectively. The predicted 10-year EFS and OS rates for Group Ⅰ were (68.3 ± 3.3) % and (80.7 ± 2.7) %, respectively, whereas those for Group Ⅱ were (62.6 ± 4.0) % and (76.8 ± 3.5) %, respectively, showing no significant difference (P(EFS)=0.201, P(OS)=0.305). The rates of infectious events (54.3% vs 69.7%, P=0.004) and asparaginase allergy (0.9% vs 9.0%, P<0.001) were significantly lower in Group Ⅰ than in Group Ⅱ. Multivariate analysis identified an initial WBC ≥50×10(9)/L (HR=1.583, 95% CI:1.060-2.365, P=0.025) and minimal residual disease (MRD) value ≥0.01% at the end of induction therapy (HR=1.300, 95% CI: 1.174-1.439, P<0.001) as the independent risk factors for EFS. MLL rearrangement (HR=3.144, 95%CI: 1.093-9.046, P=0.034) and MRD value ≥0.01% at the end of the induction therapy (HR=1.310, 95%CI: 1.152-1.488, P<0.001) were the independent risk factors for OS. Conclusion: By incorporating MRD-guided dynamic risk stratification and optimized drug regimens, the CCCG-ALL-2015 protocol significantly improved the quality of induction remission, reduced adverse events, and improved the long-term survival in adolescents (aged 10-18 years) with ALL. The MRD status at the end of induction therapy is a critical prognostic indicator and provides important guidance for individualized therapy.