Glucarpidase After High-Dose Methotrexate in Patients With Osteosarcoma

PRIMARY OBJECTIVE: I. To determine the rate of completion of 4 planned high dose methotrexate (HDMTX) doses when glucarpidase is administered after each dose. SECONDARY OBJECTIVES: I. To assess the length of hospital stay (LOS) associated with methotrexate (MTX) clearance following administration of glucarpidase 24 hours after HDMTX. II. To assess the LOS associated with all causes following administration of glucarpidase 24 hours after HDMTX. III. To assess the impact of glucarpidase administration on HDMTX efficacy. IV. To assess the safety and tolerability of 4 doses of HDMTX administered with glucarpidase in an adult osteosarcoma population. V. To assess the efficacy of glucarpidase flat dose of 1,000 units. OUTLINE: Patients receive standard of care HDMTX intravenously (IV) over 4 hours on day 1 of weeks 4, 5, 9, and 10. After 24 and 48 hours after the start of each HDMTX infusion, patients also receive glucarpidase IV over 5 minutes in the absence of disease progression or unacceptable toxicity. Additionally, patients undergo blood sample collection throughout the study. After completion of study treatment, patients are followed up for 32 weeks.