Current intensive treatment of pediatric T-cell acute lymphoblastic leukemia (T-ALL) has substantial side-effects, highlighting a need for novel biomarkers to improve risk stratification. Canonical biomarkers such as genetics and immunophenotype are largely not used in pediatric T-ALL stratification. This study aimed to validate the prognostic relevance of DNA methylation CpG island methylator phenotype (CIMP) risk stratification in two pediatric T-ALL patient cohorts: the Nordic NOPHO …