Inclusion Criteria:

• Age 18 to 75 years at the time of consent.
• Histologically or cytologically confirmed small cell lung cancer (SCLC) that is metastatic, extensive-stage, or unresectable, and relapsed or refractory after at least 1 prior systemic regimen (must include a platinum-based regimen unless contraindicated).
• At least one measurable lesion per RECIST v1.1.
• ECOG performance status 0 to 1.
• Adequate organ function (hematologic, renal, hepatic, and cardiac) as defined in the protocol (examples: ANC >= 1.0 x10^9/L, platelets >= 75 x10^9/L, creatinine clearance >= 50 mL/min, AST/ALT <= 3 x ULN, total bilirubin <= 1.5 x ULN).
• Life expectancy >= 12 weeks.
• Tumor tissue available (archival or fresh) for antigen profiling (DLL3, CD56/NCAM1, GD2).
• Negative pregnancy test for persons of childbearing potential; agreement to use effective contraception for the protocol-defined duration.

Exclusion Criteria:

• Active or uncontrolled CNS metastases or leptomeningeal disease (treated/stable CNS metastases may be allowed per protocol).
• Prior treatment with CAR-T, CAR-NK, or other gene-modified cellular therapy within 6 months (or any prior therapy directed against the investigational target antigens if it would confound safety/efficacy assessment).
• Allogeneic hematopoietic stem cell transplant within 6 months or active graft-versus-host disease.
• Active uncontrolled infection, including uncontrolled HIV, active hepatitis B or C with viremia, or active tuberculosis.
• Clinically significant cardiovascular disease (e.g., recent myocardial infarction within 6 months, uncontrolled arrhythmia, LVEF < 45%).
• Active autoimmune disease requiring systemic immunosuppression; chronic systemic corticosteroid use > 10 mg/day prednisone equivalent (unless for physiologic replacement).
• Concurrent malignancy requiring active treatment (exceptions may apply for certain non-melanoma skin cancers or in situ cancers).
• Pregnant or breastfeeding.
• Any condition that, in the investigator's opinion, would make participation unsafe or interfere with compliance.