Abstract: Small cell lung cancer (SCLC) is a highly aggressive neuroendocrine tumour with a poor prognosis. For decades, combination chemotherapy based on etoposide plus platinum (EP) constitutes the cornerstone of clinical treatment for SCLC. Although SCLC is highly sensitive to chemotherapy and radiotherapy, patients often develop resistance within a short period, leading to disease recurrence and progression. In recent years, immune checkpoint inhibitors targeting programmed death-1 (PD-1) and its ligand, when combined with chemotherapy, have significantly transformed the treatment landscape for SCLC, establishing a new standard for first-line therapeutic approaches. Numerous high-level clinical studies from global sources have extensively demonstrated that combined immunotherapy and chemotherapy can serve as a first-line treatment, providing significant overall survival (OS) benefits for patients with extensive-stage small cell lung cancer (ES-SCLC). However, challenges such as immunotherapy resistance, the lack of effective predictive biomarkers, and the management of immune-related adverse events persist in current research and clinical practice. This article aims to systematically review the current status and latest advances in first-line immunotherapy for ES-SCLC, focusing on the efficacy and safety of various immunotherapy combination regimens to provide guidance for clinical practice and future research.
Keywords: extensive-stage small cell lung cancer; first-line treatment; immune checkpoint inhibitor; immunotherapy; combination therapy
（Acta Laser Biology Sinica, 2026, 35(4): 289-297）