Day 15 MRD > or equal to 5% (excluding MLL+ infants) Cyclophosphamide† 300 mg/m2 IV/ q12 hrs on Days 22-23 Cytarabine 75 mg/m2/dose IV Days 23-26, 30-33 Thioguanine [Mercaptopurine (TPMT HET/deficient patients only) 60 mg/m2/dose PO Days 22-35 Dasatinib‡ (Ph+ participants only) 40 mg/m2 b.i.d Daily Starting Day 22 of induction to continue until end of treatment