Low-Dose Radiotherapy Plus Adebrelimab and Chemotherapy for Extensive-Stage Small Cell Lung Cancer

This is a phase II study evaluating a novel combination therapy for untreated extensive-stage small cell lung cancer. The treatment involves an initial induction phase with the drug Adebrelimab plus standard chemotherapy and low-dose radiotherapy, followed by an Adebrelimab maintenance phase. The primary objective is to assess the efficacy of this approach in prolonging overall survival (OS) and to evaluate its safety in approximately 25 patients.

Inclusion Criteria: * 1\. Patients with pathologically confirmed extensive-stage small cell lung cancer (ES-SCLC) according to VALG staging. 2\. No prior systemic therapy for extensive-stage small cell lung cancer. 3. Presence of measurable lesions as defined by RECIST 1.1. A previously irradiated lesion may be considered measurable only if clear progression occurs after radiotherapy and this previously irradiated lesion is not the only lesion. 4\. Aged 18-75 years. 5. ECOG performance status: 0-2. 6. Expected survival ≥3 months. 7. Adequate hematological and organ function, i.e., meeting the following criteria: a) Hematology (no blood transfusion or blood products and no use of G-CSF or other hematopoietic growth factors for correction within 14 days): i. Absolute neutrophil count (ANC) ≥1.5×10\^9/L (1,500/mm\^3); ii. Platelet count (PLT) ≥100×10\^9/L (100,000/mm\^3); iii. Hemoglobin (HB) ≥80 g/L. b) Renal: i. Calculated creatinine clearance (CrCl) ≥50 mL/min; ii. Urine protein \