Relapse-free survival in adolescent and adult patients with ALL according to immunophenotypic MRD level at day +14 of induction therapy. Median RFS not reached for patients with low MRD levels (< 0.5%; n = 21; gray line) versus 16 months for patients with high MRD levels (≥ 0.5%; n = 42; black line) (P = .0008).