Written informed consent from patient or parent/guardian Diagnosis of high grade osteosarcoma, localised or metastatic or high grade osteosarcoma as a second malignancy or spindle cell sarcoma of bone or relapsed high grade osteosarcoma Ability to comply with study and follow up procedures (WHO performance scale 0-2) No concomitant anti-cancer or investigational drugs during the study and complete resolution of toxicity related to previous treatment Life expectancy of at least 3 months Haematopoietic function: Absolute neutrophil count ≥1 x109/L, Platelets ≥75 x109/L Hepatic function: Bilirubin ≤1.5 x ULN Renal function: Glomerular Filtration Rate (radioisotope) ≥ 70 ml/min/1.73m2