Chemo-immunotherapy in Patients Under 18 Years of Age With Bone and Soft Tissue Sarcomas

Data from 40 patients are planned to be included in the study to randomize approximately 10 patients. This study involves patients with advanced/metastatic GD2-positive rhabdomyosarcoma after progression on 1st line of chemotherapy, advanced/metastatic GD2-positive Ewing sarcoma after progression on 1st line of chemotherapy and advanced/metastatic GD2-positive osteosarcoma after progression on 1st line of chemotherapy. All patients will receive therapy until disease progression (a total of 6 courses of immunotherapy). The primary objective of the study is to determine the efficacy and safety of dinutuximab beta with investigator's choice of chemotherapy.