Participants with resectable osteosarcoma will be randomized to one of two dose levels of robatumumab to be given intravenously. These participants will first receive robatumumab according to randomized treatment, and have surgery performed 10 to 14 days after initial dosing. Participants will be allowed to recover from surgery four to six weeks prior to additional robatumumab administration at their randomized dose level. robatumumab will then be administered on the same calendar day once every two weeks. Participants will continue to receive robatumumab until disease recurrence, or until completing a year of dosing at the same dose level assigned, whichever occurs first.~Participants with unresectable osteosarcoma or Ewing Sarcoma will be assigned treatment to robatumumab IV administered once every two weeks and will continue to receive robatumumab until disease progression. Participants who achieve a CR or PR after tumor evaluations may undergo surgical resection. After surgery, participants are eligible to receive 10 mg/kg robatumumab until disease recurrence/progression or one year of total dosing, whichever occurs first.
Participants with relapsed osteosarcoma that can be treated with surgery will be randomized to robatumumab administered intravenously (IV) at one of two dose levels. These participants will first receive robatumumab, have surgery performed, and continue to receive treatment every two weeks until a year of dosing, or until disease progression.~Participants with unresectable osteosarcoma or Ewing Sarcoma will receive robatumumab IV once every two weeks until disease progression. Participants who achieve a complete response (CR) or partial response (PR) after tumor evaluations may undergo surgical resection. After surgery, participants are eligible to receive 10 mg/kg robatumumab until disease recurrence/progression or one year of total dosing, whichever occurs first.