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

Rationale: SCLC is characterized by rapid progression, early relapse after platinum-based therapy, and antigen heterogeneity. DLL3, CD56 (NCAM1), and GD2 are frequently evaluated SCLC-associated surface targets. Dual-target CAR designs may reduce antigen-escape risk compared with single-target approaches. Investigational products: Three off-the-shelf allogeneic CAR-NK cell products are evaluated. Each product is manufactured from healthy-donor NK cells and engineered to express a dual-target CAR plus a safety switch (e.g., inducible caspase-9) and a persistence support element (e.g., IL-15 support). The exact construct features can be adapted to the sponsor's platform. Study schema: (1) Screening and biomarker assessment, including tumor antigen profiling for DLL3, CD56, and GD2 by immunohistochemistry (IHC) or validated equivalent assay. (2) Phase 1 dose escalation in up to three parallel arms (one arm per dual-target construct) using a modified 3+3 design to determine MTD and/or RP2D. (3) Interim construct selection based on a composite of safety (DLT rate), manufacturability/feasibility, in vivo expansion/persistence, and preliminary efficacy. (4) Phase 2 expansion cohort treated with the selected construct at RP2D to further characterize safety and estimate antitumor activity. Conditioning and dosing: Participants receive lymphodepleting chemotherapy (e.g., fludarabine and cyclophosphamide) followed by CAR-NK infusion(s). Because NK-cell persistence can be limited, repeat dosing within a cycle is permitted (e.g., Day 0, Day 7, Day 14), and a second cycle may be allowed in responders without prohibitive toxicity. Safety monitoring: Participants are monitored for cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), infusion reactions, cytopenias, infections, and other adverse events. An independent safety monitoring committee reviews cumulative safety at each dose level and prior to construct selection. Follow-up: Clinical follow-up continues for 24 months for efficacy and late toxicity. Long-term follow-up for gene-modified cell products (up to 15 years) may be conducted per local regulatory requirements to monitor delayed adverse events.

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.