Frontline treatment of localized osteosarcoma without methotrexate: Results of the St. Jude Children's Research Hospital OS99 trial

10036 Background: Standard treatment of osteosarcoma includes cisplatin and high-dose methotrexate (HD-MTX), but both agents are associated with significant toxicity and MTX administration requires complex pharmacokinetic monitoring. In our previous OS91 trial, the combination of carboplatin and ifosfamide with doxorubicin and HD-MTX yielded outcomes comparable to those of cisplatin-based regimens with less long-term toxicity in localized osteosarcoma. Methods: Between 1999 and 2006, we conducted a multi-institutional trial (OS99) to evaluate the activity of carboplatin, ifosfamide, and doxorubicin without HD-MTX in newly-diagnosed patients with localized osteosarcoma. Treatment comprised 12 cycles of chemotherapy given every 3 weeks: 3 consecutive cycles of carboplatin (dose targeted to AUC 8 mg/ml×min on day 1) and ifosfamide (2.65 g/m2 daily for 3 days) and one cycle of doxorubicin (25 mg/m2 daily for 3 days) followed by definitive surgery (week 12) and 2 additional cycles of carboplatin/ifosfamide and...