Investigation of [6R] 5,10-methylenetetrahydrofolate as Rescue Therapy for Osteosarcoma Patients Treated With HDMTX.

An Open-Label, Multicenter, Phase I/II Clinical Trial to Identify the [6R] 5,10-methylenetetrahydrofolate Dose with Most Favorable Safety Prospect and Confirmed Ability to Mitigate High-Dose Methotrexate Induced Toxicity during Treatment of Osteosarcoma Patients