Adaptive Phase 1/2 Study of Dual-Target CAR-NK Cells in Relapsed/Refractory Small Cell Lung Cancer (SCLC)

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.