Background  As a key strategy for immunotherapy, anti-PD-L1 therapy holds promise for the treatment of patients with small cell lung cancer (SCLC), but there is a relative paucity of data on its use in the real world.

  Objective  To analyze the efficacy and safety of SCLC patients treated with anti-PD-L1 therapy and explore the factors influencing efficacy.

  Methods  Clinical data about SCLC patients treated with PD-L1 inhibitor from January 1, 2018 to June 30, 2021 in the First Medical Center of Chinese PLA General Hospital were retrospectively analyzed. Univariate and multivariate Cox regression analyses were used to analyze the association between different factors and prognosis. Survival rates were calculated by the Kaplan-Meier method, and the differences in survival curves were evaluated using the log-rank test.

  Results  A total of 100 patients were enrolled, including 87 males and 13 females. The median age was 61.0 years. There were 31 cases in the limited stage (LS) and 69 cases in the extensive stage (ES). All of them received treatment with atelelizumab 1200 mg intravenous infusion (Ⅳ) once every 3 weeks or dulvalizumab 1 500 mg Ⅳ once every 3 weeks. Among the 100 cases, 1 case achieved complete response (CR), 69 cases achieved partial response (PR), 24 cases maintained stable (SD), and 6 cases progressed (PD). The median progression-free survival (PFS) of these 100 patients was 5.2 months. Multifactorial Cox regression analysis suggested that ECOG PS score of 0 (95% CI: 0.011-0.219, P＜0.001), limited stage (95% CI: 0.223-0.976, P=0.043) and first-line treatment using PD-L1 inhibitor (95% CI : 0.111-0.652, P =0.004) were associated with longer PFS. PFS was longer in patients receiving anti-PD-L1 therapy combined with chemotherapy compared with those receiving anti-PD-L1 therapy alone (95% CI: 0.041-0.892, P=0.035) and anti-PD-L1 therapy combined with anti-angiogenic therapy (95% CI: 0.035-0.575, P=0.006). In terms of safety, the incidence of general adverse reactions was less than or equal to 35%, and most of them were leukopenia, nausea and vomiting, and abnormal liver function. The incidence of immune-related adverse reactions was less than 10%, including pneumonia, hypothyroidism and rash. Grade 3/4 general adverse reactions was less than or equal to 13%, grade 3/4 immune-related adverse reactions was less than or equal to 2%, and no death-related adverse events occurred.

  Conclusion  Immunotherapy with PD-L1 inhibitors is a promising treatment for SCLC, with high efficacy and tolerable safety. It is recommended to use immunotherapy with PD-L1 inhibitors combined with chemotherapy in the first-line treatment as early as possible. Preliminary analysis finds that among the multiple treatment options for SCLC, immunotherapy combined with anti-angiogenic therapy is inferior to immunotherapy combined with chemotherapy, whereas immunotherapy combined with chemotherapy plus anti-angiogenic therapy is not superior to immunotherapy combined with chemotherapy.