This study is a FIH dose escalation clinical study, with single arm, open label and design, in order to observe the preliminary safety and Pharmacokinetic of SNC115 Injection in participants with Recurrent/refractory small cell lung cancer and Lung large cell neuroendocrine carcinoma.

The study will enroll at most 35 participants diagnosed with Recurrent/refractory small cell lung cancer or Lung large cell neuroendocrine carcinoma.

There will be about 5 preset dose groups in this clinical trial, Participants will be enrolled from low dose group to high dose group. Dose escalation will be decided by the SRC (Safety Review Committee). There will be expanded cases in the aim dose group.

The protocol will be performed into Screening period (-30+ days), Mononuclear cells acquisition, Lymphodepletion (-5~-3 days), SNC115 Injection infusion and DLT observation period (day 0~28days), and follow-up period (1-5 years). According to the administration strategy, we will start from single administration.

Inclusion Criteria:

1. Age ≥ 18 years old, regardless of gender;
2. Histological or cytological diagnosis of SCLC or pulmonary LCNEC (WHO 2021)
3. Relapse or refractory after receiving at least first-line standard therapy, or inability to tolerate first-line standard therapy
4. Eastern Cooperative Oncology Group score 0-1;
5. At least one measurable tumor lesion (other than brain metastases) according to solid tumor response criteria 1.1 (RECIST1.1)
6. Measurable lesions with an expected survival of more than 3 months;
7. Expected survival ≥12 weeks.
8. Adequate organ and bone marrow function.
9. The subjects agreed to use reliable contraceptive methods for contraception within 1 year from the signing of informed consent to reinfusion.
10. Voluntarily participate in clinical trials and sign informed consent.

Exclusion Criteria:

1. Known allergic reaction, hypersensitivity, intolerance or contraindication to SNC115 Injection or any component of drugs that may be used in the study (including fludarabine, cyclophosphamide and Tocilizumab).
2. Have received any previous CAR-T therapy or other gene-modified cell therapy.
3. Have received any previous treatment targeting DLL3.
4. Uncontrolled pleural effusion, pericardial effusion, and ascites (uncontrolled refers to repeated drainage).
5. Untreated (including new lesions or progression after previous treatment) or symptomatic brain metastases.
6. Have medical history of study excluded thrombosis, Systemic autoimmune disease, cardiopathy, cancer, infection disease and so on.