Safety and Efficacy of CAR-T Cell Therapy for Relapsed/refractory Neuroblastoma and Desmoplastic Small Round Cell Tumors: a Single-arm, Open-label Trial.

Inclusion Criteria: 1. Patients who are diagnosed as relapsed/refractory neuroblastoma or relapsed/refractory desmoplastic small round cell tumors; 2. Age 1-50 years, any gender; 3. Agree to participate in the trial and sign a written informed consent form; 4. Expected survival of ≥12 weeks; 5. Karnofsky performance status (for patients ≥16 years) or Lansky performance status (for patients \<16 years) (Appendix 1) must be at least 50; 6. Good function of major organs: 1. Liver function: ALT ≤ 5 times the upper limit of normal for the corresponding age, and bilirubin ≤ 2.0 mg/dL, except for patients with Gilbert-Meulengracht syndrome. Patients with Gilbert-Meulengracht syndrome who have bilirubin ≤ 3.0 times the upper limit of normal and direct bilirubin ≤ 1.5 times the upper limit of normal may be included; 2. Renal function: Plasma creatinine ≤ 1.5 times the upper limit of normal, or estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73m²; 3. Pulmonary function: Oxygen saturation ≥ 95% in room air; 4. Cardiac function: Left ventricular ejection fraction (LVEF) ≥ 45%; 7. Patients using the following medications must meet the following conditions: Steroids: Steroid treatment doses must be stopped at least 2 weeks before CAR-T infusion. However, physiological replacement doses of steroids are allowed; Immunosuppressants: Any immunosuppressive drugs must be stopped at least 4 weeks before enrollment; Anti-proliferative treatments other than lymphodepleting chemotherapy within two weeks before infusion; CNS disease prophylaxis must be stopped 1 week prior to CAR-T infusion (e.g., intrathecal methotrexate injection); 8. Patients of childbearing potential (both male and female) must agree to use reliable contraception methods (hormonal or barrier methods or abstinence) with their partner until at least 12 months after CAR-T cell infusion, and until two consecutive flow cytometry or PCR tests show no CAR-T cells in the body; 9. If the subject cannot provide suitable T cells for CAR-T preparation, T cells from a healthy donor may be collected for preparation. Exclusion Criteria: * Patients with any of the following items will not be enrolled in this study: 1. Patients with increased intracranial pressure or altered consciousness; 2. Patients who have received radiation therapy within 2 weeks prior to infusion; 3. Patients with active hepatitis B (defined as HBV DNA \> 500 IU/mL) or hepatitis C (HCV RNA positive); 4. HIV-positive patients or patients with a positive syphilis test; 5. Patients with uncontrolled acute life-threatening bacterial, viral, or fungal infections (e.g., positive blood cultures within ≤72 hours before infusion); 6. Patients with unstable angina and/or myocardial infarction within 6 months prior to screening; 7. Patients with a history of or concurrent malignancies, except for the following conditions: 1. Basal cell carcinoma or squamous cell carcinoma that has been adequately treated (sufficient wound healing required before study enrollment); 2. Carcinoma in situ of the cervix or breast that has been cured, with no signs of recurrence for at least 3 years before the study; 3. Primary malignant tumors that have been completely resected and have been in complete remission for ≥5 years; 8. Pregnant or breastfeeding female patients; 9. Patients with uncontrolled arrhythmias that have not been managed medically; 10. Patients who need oral anticoagulation therapy within 1 week before CAR-T cell infusion; 11. Patients with active neuroautoimmune or inflammatory diseases (e.g., Guillain-Barré syndrome, amyotrophic lateral sclerosis); 12. Other conditions deemed inappropriate for participation in the clinical study by the investigator. Patients enrolled in the clinical study must meet the inclusion criteria and not meet the exclusion criteria.