Kaplan-Meier estimates of RFS using the combined gene expression classifiers for RFS and MRD in an independent cohort of 84 children with high-risk ALL. (A) The gene expression classifier for RFS separates children into low- and high-risk groups in an independent cohort of 84 children with high-risk ALL treated on COG Trial 1961.^14,16  (B) Application of the combined gene expression classifiers for RFS and MRD shows significant separation of 3 risk groups: low (47 of 84, 56%), intermediate (22 of 84, 26%), and high (15 of 84, 18%), similar to our initial cohort (Figure 3C).