Regulatory agency commitment fulfilled.

This study is an observational safety surveillance study designed to prospectively assess patients with high-grade osteosarcoma who are candidates for treatment with mifamurtide within the context of prevailing standard oncology practice

Inclusion Criteria

Each patient must meet all of the following inclusion criteria to be enrolled in the study:

• Male or female aged 2 to 40 years
• Confirmed pathological diagnosis of newly-diagnosed, nonmetastatic, resectable, primary, high-grade osteosarcoma
• Have completed definitive surgery (or other local ablation technique)
• Have a treatment regimen that includes mifamurtide and a minimum of 2 recognized chemotherapy agents in the treatment of osteosarcoma (cisplatin, doxorubicin, high-dose methotrexate or ifosfamide)
• Organ function deemed satisfactory to receive planned chemotherapy containing at minimum 2 of the recognized chemotherapy agents in the treatment of osteosarcoma
• Voluntary Written Consent

Exclusion Criteria

Patients meeting any of the following exclusion criteria are not to be enrolled in the study:

• Female patients who are lactating and breastfeeding or have a positive serum pregnancy test during the screening period
• History of pericarditis or pleuritis
• Have low-grade osteosarcoma or parosteal or periosteal sarcoma
• Have osteosarcoma associated with Paget's disease
• Current treatment with any anticancer investigational products at the time of enrollment in this study

The study population consists of patients with high-grade osteosarcoma who are candidates for treatment with mifamurtide within the context of prevailing standard oncology practice.