Treatment schema.

Patients with newly diagnosed ALL were randomized to 1 of 3 treatments: intravenous MP (1 g/m²) over 6 hours (MP); oral MTX (30 mg/m² every 6 hours, 6 doses) followed at 24 hours by intravenous MP (1 g/m²) over 6 hours (LDMTX plus MP); or intravenous MTX (1 g/m²) over 24 hours followed by intravenous MP (1 g/m²) over 6 hours (HDMTX plus MP). DNPS rates were measured in leukemia cells from bone marrow (BM) aspirates obtained at diagnosis and at 20 hours after the start of MP infusion (corresponding to 44 hours after the start of MTX therapy). MTXPG concentrations were measured in bone marrow leukemia cells obtained at 44 hours after initiation of chemotherapy in patients randomized to MTX plus MP.