Liposomal Irinotecan Combination Regimen for First-line Treatment of Small Cell Lung Cancer

Inclusion Criteria:

* Patients fully understand the study, voluntarily participate and sign an informed consent form (ICF)；
* Age ≥18 years；
* Patients with pathologically or histologically confirmed extensive stage small cell Lung cancer (according to the Veterans Administration Lung Study Group, VALG staging system)；
* The patient had not previously received any form of antitumor therapy；
* According to RECIST1.1 criteria, the patient had at least one measurable target lesion；
* Eastern Cooperative Oncology Group（ECOG）Physical status score: 0-2；
* The expected survival time is ≥3 months；
* Absolute neutrophil count (ANC) ≥1.5×10\^9/L, platelets ≥100×10\^9/L, and hemoglobin ≥90 g/L (no blood transfusion, blood products, correction with granulocyte colony stimulating factor or other hematopoietic stimulating factor within 14 days prior to laboratory examination)；
* Serum creatinine ≤1.5 times the upper limit of normal value; AST and ALT ≤2.5 times the upper limit of normal (≤5 times the upper limit of normal for patients with liver invasion); Total bilirubin ≤1.5 times the upper limit of normal (≤3 times the upper limit of normal for patients with liver invasion)；
* Women of childbearing age must have had a pregnancy test (serological) negative within 7 days prior to enrollment and be willing to use an appropriate method of contraception during the trial period and for 6 months after the last dose of the test drug.

Exclusion Criteria:

* Patients with large cell neuroendocrine tumor and mixed small cell carcinoma；
* Patients with active brain metastases or central nervous system invasion； confirmed by imaging evaluation and/or biopsy (prednisone equivalent dose ≥10mg)；
* Allergic reaction to any investigational drug or its ingredients；
* The patient has previously received other antibodies/drugs that target immune checkpoints, such as PD-1, PD-L1, CTLA4, etc；
* Serious, uncontrolled comorbidities that could affect the study results, including but not limited to serious infections, diabetes, or cardiovascular and cerebrovascular disease, were identified；
* Imaging confirmed intestinal obstruction；
* It has uncontrollable ascites, abdominal infection and pyloric obstruction；
* Cardiac function and disease: a history of myocardial infarction, unstable angina pectoris, severe unstable ventricular arrhythmia or any other arrhythmia requiring treatment, a history of clinically serious pericardial disease, or electrocardiographic evidence of acute ischemic or active conduction system abnormalities in the 6 months prior to recruitment；
* Hepatitis B, hepatitis C active infection (hepatitis B surface antigen positive and hepatitis B DNA more than 1x103 copies /mL; more than 1x103 copies /mL of HCV RNA)；
* Human immunodeficiency virus (HIV) infection (HIV antibody positive);
* Previous or current co-occurrence of other malignancies (in addition to non-melanoma basal cell carcinoma of the skin that is effectively controlled, breast/cervical carcinoma in situ, and other malignancies that have been effectively controlled without treatment within the past five years);
* Pregnant and lactating women and patients of childbearing age who do not want to use contraception;
* The investigators determined that patients were not suitable to participate in this study.