Inclusion Criteria:

• patients >=2 years of age;
• progressive, recurrent or refractory Ewing's sarcoma, or recurrent or refractory osteosarcoma, synovial sarcoma, rhabdomyosarcoma, or other sarcomas of the following sub-types: alveolar soft part sarcoma, desmoplastic small round cell tumor, extraskeletal myxoid chondrosarcoma, clear cell sarcoma and myxoid liposarcoma.

Exclusion Criteria:

• clinically significant unrelated systemic illness which would compromise the patient's ability to tolerate the investigational agent, or interfere with the study procedures or results;
• known hypersensitivity to any of the components of R1507 or prior hypersensitivity reactions to monoclonal antibodies;
• current or previous treatment (within last 6 months) with chronic pharmacological doses of corticosteroids, immunosuppressive agents or medications that inactivate or may interfere with the pharmacological activity of R1507;
• current or prior therapy with IGF inhibitor (monoclonal or specific kinase inhibitor);
• history of solid organ transplant;
• other malignant disease diagnosed within the previous 5 years, excluding intra-epithelial cervical neoplasia or non-melanoma skin cancer.