This study investigates the effects of different chemotherapy combinations on patients with non-metastatic extracranial Ewing sarcoma. Ewing sarcoma is a type of cancer that occurs in bones or in the soft tissue around the bones. The purpose of this study is to compare the standard chemotherapy treatment with a new combination that includes an investigational medication.

Participants will receive either the standard chemotherapy treatment or the standard treatment plus an investigational medication. This study will help determine if adding the investigational medication improves event-free and overall survival in children and young adults. Participants will be randomly assigned to one of the study arms and will receive their treatment accordingly.

• Who can participate: Children and young adults diagnosed with non-metastatic extracranial Ewing sarcoma may be eligible to participate. Specific eligibility criteria will be provided upon inquiry.
• Study details: Participants will be randomly assigned to receive either the standard chemotherapy or the standard chemotherapy with an investigational medication. The investigational medication is being tested to see if it improves survival outcomes.