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 orrelapsed/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:

7. Liver function: ALT ≤ 5 times the upper limit of normal for the correspondingage, and bilirubin ≤ 2.0 mg/dL, except for patients with Gilbert-Meulengrachtsyndrome. Patients with Gilbert-Meulengracht syndrome who have bilirubin ≤ 3.0times the upper limit of normal and direct bilirubin ≤ 1.5 times the upperlimit of normal may be included;

8. Renal function: Plasma creatinine ≤ 1.5 times the upper limit of normal, orestimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73m²;

9. Pulmonary function: Oxygen saturation ≥ 95% in room air;

10. Cardiac function: Left ventricular ejection fraction (LVEF) ≥ 45%;

11. Patients using the following medications must meet the following conditions: Steroids: Steroid treatment doses must be stopped at least 2 weeks before CAR-Tinfusion. However, physiological replacement doses of steroids are allowed;Immunosuppressants: Any immunosuppressive drugs must be stopped at least 4 weeksbefore enrollment; Anti-proliferative treatments other than lymphodepletingchemotherapy within two weeks before infusion; CNS disease prophylaxis must bestopped 1 week prior to CAR-T infusion (e.g., intrathecal methotrexate injection);

12. Patients of childbearing potential (both male and female) must agree to use reliablecontraception methods (hormonal or barrier methods or abstinence) with their partneruntil at least 12 months after CAR-T cell infusion, and until two consecutive flowcytometry or PCR tests show no CAR-T cells in the body;

13. If the subject cannot provide suitable T cells for CAR-T preparation, T cells from ahealthy 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 hepatitisC (HCV RNA positive);

4. HIV-positive patients or patients with a positive syphilis test;

5. Patients with uncontrolled acute life-threatening bacterial, viral, or fungalinfections (e.g., positive blood cultures within ≤72 hours before infusion);

6. Patients with unstable angina and/or myocardial infarction within 6 monthsprior to screening;

7. Patients with a history of or concurrent malignancies, except for the followingconditions:

8. Basal cell carcinoma or squamous cell carcinoma that has been adequatelytreated (sufficient wound healing required before study enrollment);

9. Carcinoma in situ of the cervix or breast that has been cured, with nosigns of recurrence for at least 3 years before the study;

10. Primary malignant tumors that have been completely resected and have beenin complete remission for ≥5 years;

11. Pregnant or breastfeeding female patients;

12. Patients with uncontrolled arrhythmias that have not been managed medically;

13. Patients who need oral anticoagulation therapy within 1 week before CAR-T cellinfusion;

14. Patients with active neuroautoimmune or inflammatory diseases (e.g.,Guillain-Barré syndrome, amyotrophic lateral sclerosis);

15. Other conditions deemed inappropriate for participation in the clinical studyby the investigator.

Patients enrolled in the clinical study must meet the inclusion criteria and not meet the exclusion criteria.