Outcomes according to MRD response at the end of reinduction treatment block 1. EFS probabilities for pediatric patients with first isolated or combined BM relapses of B-lymphoblastic leukemia in morphological CR2. (A) 5-year EFS probabilities in all patients according to MRD response using flow cytometry–based assays (negative < 0.01%; positive ≥ 0.01%). (B) Analysis includes patients with early BM relapses (< 36 months from diagnosis) only. (C) Analysis includes patients with late BM relapses (≥ 36 months from diagnosis) only (unpublished data).