JCCG ALL-B12: Evaluation of Intensified Therapies With Vincristine/Dexamethasone Pulses and Asparaginase and Augmented High-Dose Methotrexate for Pediatric B-ALL.

Purpose: The JCCG ALL-B12 clinical trial aimed to evaluate the effectiveness of unvalidated treatment phases for pediatric ALL and develop a safety-focused treatment framework.

Patients and methods: Patients age 1-19 years with newly diagnosed B-ALL were enrolled in this study. These patients were stratified into standard-risk (SR), intermediate-risk (IR), and high-risk (HR) groups. Randomized comparisons assessed the effectiveness of vincristine (VCR)/dexamethasone pulses in the SR group, evaluated the effects of L-asparaginase (ASP) intensification in the IR group, and compared standard consolidation including block-type treatment with experimental consolidation with high-dose methotrexate (HD-MTX) intensified with VCR and ASP in the HR group.

Results: Of 1,936 patients enrolled, 1,804 were eligible for the experimental treatment. The overall 5-year event-free survival and overall survival rates were 85.2% (95% CI, 83.5 to 86.8) and 94.3% (95% CI, 93.1 to 95.3), respectively. The cumulative incidence of relapse and postremission nonrelapse mortality was 13.2% (95% CI, 11.6 to 14.8) and 0.6% (95% CI, 0.3 to 1.0), respectively. Random assignment in the SR group showed no significant benefit from pulse therapy. In the IR group, ASP intensification had limited effects. In the HR group, standard block therapy and HD-MTX yielded equivalent outcomes.

Conclusion: The ALL-B12 trial achieved favorable outcomes in a nationwide cohort by stratifying treatment on the basis of risk and balancing treatment intensity. This study not only demonstrated that existing standard of care can be further refined but also indicated that improvement in outcomes with intensified chemotherapy has reached a plateau.