A Phase 1/2 Study of DS-8201a in Children, Adolescents, or Young Adults with Osteosarcoma, Wilms Tumor, and Desmoplastic Small Round Cell Tumor

The purpose of this study is to find out how well DS-8201a works in treating recurrent osteosarcoma (osteosarcoma that has come back after treatment) and what side effects is has on adolescents and young adults with HER2 positive recurrent osteosarcoma. The treatment involves giving DS-8201a through a vein (IV) once every 3 weeks. This 3 week time period is known as a cycle. You can receive up to 35 cycles (or about 24 months) of treatment as long as your tumor does not grow too much and you are not having any bad side effects.

Are you Eligible? (Inclusion Criteria)

• Patients must have a confirmed diagnosis of osteosarcoma (from either original diagnosis or recurrence).
• Patients must be between 12 years and 39 years of age.
• Patients must also meet all eligibility criteria as outlined in the study protocol.