2. Consolidation Treatment (8 weeks) High Dose Methotrexate (HDMTX) 2.5 gm/ (low risk), or targeted 65 μM (std/high-risk) days 1, 15, 29 and 43. Mercaptopurine 50 mg/m2/day Days 1 to 56. All patients will receive triple intrathecal therapy every other week for four doses on Days 1, 15, 29, and 43. Dose is age dependent.