This figure explains the St. Jude (SJ) risk stratification used in this study and shows how it compares with NCI risk stratification. SJ classifies patients as low risk, standard risk, or high risk. Patients with B-ALL who were ≥1 year but <10 years of age with a white blood cell (WBC) count of <50 × 10⁹/L at presentation (equivalent to NCI standard risk), in addition to those who had the ETV6::RUNX1 fusion or a DNA index ≥1.16, were classified as provisional low risk. Patients with BCR::ABL1 were considered high risk. The remaining patients, including those with TCF3::PBX1, hypodiploidy (<44 chromosomes), central nervous system-3 status (≥5 leukocytes/μL of cerebrospinal fluid with blasts or cranial palsy), or testicular leukemia at diagnosis, were considered provisional standard risk, which category includes most NCI high-risk patients who are not classified as provisional SJ low risk or high risk. In SJ trials, MRD levels were evaluated by flow cytometry in bone marrow samples collected on day 19 (in Total XV) or day 15 (in Total XVI) and at the end of remission induction and were used for final risk classification. Provisional low-risk patients with MRD ≥ 1% on day 15 or day 19 of induction or MRD of 0.01% to <1% at the end of induction were classified as standard risk. Patients with MRD ≥1% at the end of induction or persistent MRD during the consolidation phase were classified as high risk. EOI, end of induction.