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

Inclusion Criteria: 1. Signed written informed consent form; 2. Age under 18 years of age; 3. Histologically confirmed GD2-positive osteogenic sarcoma, Ewing's sarcoma, soft tissue and undifferentiated sarcomas; 4. Prior to study enrollment, patients must have been treated with one or more lines of adequate chemotherapy and must have relapsed on this therapy or have refractoriness to it; 5. General satisfactory condition of the patient (Lansky scale activity 80-100% (children under 16 years of age), Karnofsky scale 80-100% (children over 16 years of age); ECOG - 0-1); 6. Sufficient cardiopulmonary reserves of the patient's organism (ECG (ELECTROCARDIOGRAPHY) data within normal limits, ventricular ejection fraction \> 75% of the upper limit of normal; 7. Adequate liver function (ALT (ALANINE AMINOTRANSFERASE) ≤ 2.5 \* VGN, AST (ASPARTATE AMINOTRANSFERASE) ≤ 2.5 \* VGN), kidney (creatinine \<1.5 \* VGN), red bone marrow (granulocytes\> 2.0 \* 109/L, platelets\> 150 \* 109/L). Six months later, two additional criteria were formulated: 8. Life expectancy at the time of initiation of therapy within the framework of the study is not less than 12 months 9. Oligometastasis disease (presence of 1 to 5 distant metastatic foci) at restaging at the time of the decision to include the patient in the study; Exclusion Criteria: 1. Withdrawal of consent by the patient or his/her parent/guardian. 2. Exclusion of the patient by the investigator for safety or ethical reasons.