Long-term Results of the Risk-adapted Treatment for Childhood B-Cell Acute Lymphoblastic Leukemia: Report From the Japan Association of Childhood Leukemia Study ALL-97 Trial

Abstract

This study was conducted as the first clinical trial by Japan Association of Childhood Leukemia Study to improve the outcome of B-cell acute lymphoblastic leukemia and explore a less toxic reinduction block. From 1997 to 2002, 563 patients with B-cell acute lymphoblastic leukemia aged 1 to 15 years were enrolled. The patients were assigned into 4 risk groups (standard, intermediate, high, or extremely high risk) and treated with regimens intensified according to the risk. Two randomized trials were conducted to compare 2 regimens with and without a 3-week reinduction therapy in the standard-risk group, and to compare the efficacy of pirarubicin with daunorubicin in the intermediate-risk and high-risk groups. Prophylactic cranial irradiation was restricted in patients with high or extremely high risk. The event-free survival (EFS) rate at 10 years for all patients was 77.0%. Those in the standard-risk to extremely high-risk groups were 79.3%, 72.5%, 71.7%, and 66.3%, respectively. The 15-week induction/consolidation not followed by reinduction produced 76.4% of the EFS at 10 years comparable with the regimen with reinduction therapy. Pirarubicin at 25 mg/m administered 11 times throughout the treatment produced the EFS comparable with daunorubicin at 30 mg/m. The trial produced high survival rates in NCI-HR patients, although the outcomes in NCI-SR patients were not satisfactory possibly due to less intensive central nervous system-directed therapy.