Adebrelimab and Concurrent Radiochemotherapy as First-line Treatment for Extensive-stage Small-cell Lung Cancer

Inclusion Criteria: 1. Aged 18-75 years; 2. Histologically confirmed ES-SCLC (per the Veterans Administration Lung Study Group \[VALG\] staging system) ; 3. Must sign a written informed consent form prior to any study specific procedures; 4. No prior treatment for ES-SCLC; 5. No more than 5 lesions (including metastases),and at least one measurable lesion that meets RECIST 1.1 evaluation criteria; 6. Life expectancy more than 3 months; 7. ECOG PS 0-1 Exclusion Criteria: 1. Previous treatment with radiochemotherapy for limited-stage small cell lung cancer; 2. Subjects who previously received systemic antitumor or Immune checkpoint inhibitor therapy ; 3. Active autoimmune disease that has required systemic treatment in the past 2 years (i.e. with use of disease modifying agents, corticosteroids or immunosuppressive drugs); replacement therapy (e.g., thyroxine, insulin, or physiologic corticosteroid replacement therapy for adrenal or pituitary insufficiency, etc.) is not considered a form of systemic treatment; 4. Active brain metastases, Leptomeningeal metastasis(untreated central nervous system (CNS) metastases unless asymptomatic and lesion size\<1cm; 5. Patients with spinal cord compression; 6. Patients with multiple liver metastases(except isolated lesion and lesion size\<2cm); 7. Uncontrollable third cavity effusion (e.g. a large amount of pleural effusion, ascites, or pericardial effusion, etc.) requiring repeated drainage, which was judged by the investigator to be unsuitable for study; 8. The investigator judges that there are any patients who endanger the patient's safety, interfere with the study assessment, and have poor compliance.