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. 6 cycles of treatment with dinutuximab beta are provided in combination with 6-8 cycles of chemotherapy during the induction therapy phase. Switching from one chemotherapy regimen to another is not allowed. Dinutuximab beta should be administered as a slow intravenous infusion through a separate catheter using an infusion pump. All patients will receive therapy until disease progression (a total of 6 courses of immunotherapy). Treatment response will be assessed by the investigator after 2, 4 cycles of treatment and at the end of the reinduction therapy period (i.e., after 6 cycles of dinutuximab beta treatment and 6 - 8 cycles of polychemotherapy). Treatment response will be assessed by tumor response according to the criteria for response assessment in the treatment of solid tumors (RECIST 1.1). After discontinuation of therapy, all patients will be followed up for 6 months. All patients should be followed up to assess survival unless consent is withdrawn. Long-term follow-up/survival assessment visits will be performed monthly until death, withdrawal of consent, or study termination, whichever occurs first.