Efficacy and Biomarkers of the Second-line Treatment of Adebelizumab Combined With Irinotecan Liposome in Advanced Small Cell Lung Cancer

Inclusion Criteria: * 1\. Age: 18-75 years old; 2. Small cell lung cancer diagnosed by histology; Compound small cell lung cancer is not allowed; 3. Progress in receiving first-line chemotherapy combined with immunotherapy (including PD-1 inhibitor and PD-L1 inhibitor); 4. According to RECIST 1.1 standard, there is at least one measurable objective lesion; 5.ECOG score 0-1; 6. The functions of important organs meet the following requirements:Bone marrow function: neutrophils ≥1.5×109/L, platelets ≥100×109/L, hemoglobin concentration ≥ 90g/L;Liver function: bilirubin ≤ 1.5× ULN; Aspartate aminotransferase and glutamate aminotransferase ≤2.5×ULN, and AST and ALT ≤ 5× ULN in case of liver metastasis; Total bilirubin ≤1.5 times the upper limit of normal value;Renal function: serum creatinine ≤1.5×ULN, or creatinine clearance rate (CCR) ≥ 60 ml/min; 7. Expected survival \> 12 weeks;Patients have good compliance with the planned treatment, can understand the research process of this study and sign a written informed consent. Exclusion Criteria: 1\. Irinotecan liposome or Irinotecan has been used before; 2. Severe heart and lung diseases, new york Heart Association (NYHA) scores that patients with heart diseases above Grade II (including Grade II); 3. Patients with severe systemic infection or other serious diseases; 4. Patients who are known to be allergic or intolerant to chemotherapy drugs or their accessories; 5. Other malignant tumors have appeared in the past 5 years, except cured cervical carcinoma in situ and non-melanoma skin cancer; 6. Patients of childbearing age during pregnancy or lactation, and those who refused to take appropriate contraceptive measures during this experiment; 7. Have participated in clinical studies of other drugs within 21 days before the first dose of the study drug is given; 8. Combined with active autoimmune diseases and inflammatory diseases; 9. Grade 3-4 immune-related adverse reactions occurred during previous immunotherapy; 10. Symptomatic brain metastasis and meningeal metastasis; 11. Before the first administration, you are receiving long-term systemic corticosteroid therapy with prednisone \> 10mg/d or equivalent anti-inflammatory active drugs or any form of immunosuppressive therapy. Subjects who need bronchodilators, inhaled or topical steroids or local steroid injections can be included in this study; 12. Patients with a large amount of serous cavity effusion, or serous cavity effusion with symptoms, or poor control of serous cavity effusion (poor control is defined as: puncture and drainage are needed twice or more in one month);The researcher judges the patients who are not suitable to participate in this study. \-