This Study is an Open-lable, Early Study to Evaluate the Safety, Feasibility, Cytokinetics, and Preliminary Efficacy of GC511B in DLL3+ Relapsed/Refractory Small Cell Lung Cancer.

Inclusion Criteria: * 1.Trial articipant must be ≥ 18 years and ≤75 years of age at the time of signing the ICF. Type of Subjects and Disease Characteristics * 2.ECOG performance status 0-2. * 3.Life expectancy ≥ 12 weeks. * 4.At least 1 TL meeting RECIST v1.1 at screening. Tumor assessment by CT scan or MRI must be performed within 28 days prior to apheresis. 1. A lesion can be considered TL if the lesion previously subjected to radiotherapy has a clear boundary, is measurable as per RECIST v1.1, and has clear progression during or after the latest treatment; 2. If a fresh biopsy sample is selected at screening from a tumor lesion, the tumor lesion should not be selected as a TL unless imaging is performed at least approximately 2 weeks after the biopsy to allow time for healing. In a case where there is only one measurable TL, caution should be taken when obtaining biopsy tissues during the treatment period. * 5.Archival or freshly biopsied tumor tissue for assessment of DLL3 expression levels can be provided. * 6.Adequate organ function: a.Blood function: i.Hemoglobin ≥ 9 g/dL (without transfusion or erythropoietin therapy within 2 weeks prior to screening assessment); ii.Absolute neutrophil count ≥ 1.5×10\^9/L and absolute lymphocyte count ≥ 0.6×10\^9/L (without G-CSF use within 2 weeks prior to screening assessment);iii.Platelet count ≥ 75×10\^9/L (without platelet transfusion or recombinant human thrombopoietin within 2 weeks prior to screening assessment). b.Hepatic function (based on normal values as defined by the clinical study site):i.Serum TBL ≤ 1.5 ×ULN;ii.ALT or AST ≤ 2.5×ULN in the absence of liver metastases; ALT and AST ≤ 5×ULN in the presence of liver metastases. c.Renal function (based on normal values as defined by the clinical study site): i.Serum creatinine ≤ 1.5 × ULN, or creatinine clearance ≥ 60 mL/minute calculated using the Cockcroft-Gault formula, or creatinine clearance ≥ 60 mL/minute calculated using 24-hour urine.ii.Urine protein \<++. For trial participants with proteinuria ≥ ++ on urine test paper at baseline, 24-hour urine must be collected and the content of protein in urine within 24 hours must be \< 1 g. d.Coagulation function (based on normal values as defined by the clinical study site):i.PT≤1.5×ULN；ii.Thrombin time ≤ 1.5×ULN;iii.aPTT≤1.5×ULN。 e.Cardiac function:i.New York Heart Association classification \< class 3;ii.LVEF ≥ 50%. * 7.Able to establish venous access and, in the judgment of the investigator, suitable for PBMC collection. * 8.Women of childbearing potential must be non-lactating, and women of childbearing potential must have a negative result of highly sensitive serum pregnancy test during screening. * 9.All trial participants of childbearing age (including women of childbearing age and males with partners) must agree to take medically acceptable effective contraception measures as mentioned in Appendix F throughout the treatment period and for 2 years after the last CAR-T product reinfusion or until a negative CAR copy test, whichever occurs later. * 10.Male trial participants must agree not to donate sperm and female trial participants must agree not to donate eggs throughout the treatment period and for 2 years after the last CAR-T product reinfusion or until a negative CAR copy test, whichever occurs later. * 11.Capable of signing ICF (as mentioned in Appendix A), which includes compliance with the requirements and restrictions listed in the ICF and in the protocol. * 12.The trial participant has provided ICF before starting any study-specific activity/procedure. * 13.Able to communicate well with the investigator, and willing to comply with the study plan and able to complete the study as required. Exclusion Criteria: * 1.Pregnant or breastfeeding females, or female trial participants with a positive pregnancy test result during the screening period (females not of childbearing potential are not required to receive a pregnancy test, such as metrectomy and/or bilateral oophorectomy, or amenorrhea for ≥ 12 months). * 2\. Trial participants who have received a live vaccine within 4 weeks prior to initiation of apheresis or who plan to receive any vaccine (other than coronavirus disease 2019 vaccine) during the study. * 3.Trial participants has a history of other acquired or congenital immunodeficiency; trial participants received organ transplant or bone marrow transplant. * 4.The trial participants has a serious arterial/venous thromboembolic event or cerebrovascular accident within 6 months before apheresis, such as deep venous thrombosis (excluding asymptomatic and untreated muscle venous thrombosis), pulmonary embolism, cerebral infarction, cerebral hemorrhage and except for myocardial infarction that is asymptomatic and does not require clinical intervention. * 5.The trial participant has hereditary or acquired haemorrhage and thrombophilia (e.g., hemophilia, coagulation disorder, splenomegaly); * 6.The trial participant has a QTc interval \> 450 ms (males) or \> 470 ms (females) during the screening period; the trial participant has a family or personal history of long or short QT syndrome;The trial participants had a history of unstable angina pectoris, severe arrhythmia, severe non-ischemic cardiomyopathy, or had undergone myocardial infarction or cardiovascular surgery within 6 months. * 7.The trial participant has other diseases that may seriously endanger the safety of the trial participant or affect the completion of the study, such as peptic ulcer, intestinal obstruction, intestinal paralysis, pulmonary fibrosis, renal failure, and uncontrolled diabetes. * 8.The trial participants has an active or ongoing infection requiring systemic intravenous treatment (the trial participant may start study treatment 2 weeks after completion of anti-infective therapy). * 9.History of any autoimmune nervous system disorder, including but not limited to: multiple sclerosis, neuromyelitis optica spectrum disorde