Preventing Nephrotoxicity and Ototoxicity From Osteosarcoma Therapy

0.3 mg/kg IV over 15 min immediately prior to cisplatin as a loading dose on days 1 \& 2 followed by 1.3 mg/kg IV infused over 4 h concurrent with the 4 h cisplatin infusion on days 1 \& 2 of treatment Cycles 1 \& 2 (Treatment Arms 1, 3) OR Cycles 3 \& 4 (Treatment Arms 2, 4)

High-dose methotrexate (12 g/sq m, maximum dose 20 g) will be infused over 4 hours or 12 hours