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Efficacy and safety of PD-1/PD-L1 antibody combined with chemotherapy as second-line or third-line treatment for metastatic small cell lung cancer.

e20574 Background: For a small subset of patients, immune checkpoint blockade heralds a promising strategy for achieving disease control in small cell lung cancer (SCLC). Nivolumab or pembrolizumab monotherapy has been granted accelerated approval for treatment of patients with extensive-stage SCLC with disease progression after platinum-based chemotherapy and at least one other line of therapy. Moreover, Based on IMpower133 and CASPIAN data, addition of PD-L1 antibody such as atezolizumab or durvalumab to first-line platinum-based chemotherapy prolongs overall survival over chemotherapy alone. However, it remains exclusive that whether PD-1/PD-L1 antibody combined with chemotherapy is effective against extensive-stage SCLC when progressed on previous chemotherapy. Methods: We reviewed patients with extensive-stage SCLC who have failed in first-line or beyond chemotherapy and received PD-1/PD-L1 antibodies with chemotherapy in a single institute. The efficacy and safety were evaluated. The primary end point was the objective response rate according to Response Evaluation Criteria in Solid Tumors, version 1.1. Results: A total of 11 patients were included in this retrospective cohort study. The median age was 46 years (range from 29 to 62). Seven patients were male. Four were current or former smokers. Six received two prior therapies. Nine had previously received radiation therapy. PD-1 and PD-L1 inhibitors were administrated in 5 and 6 patients, respectively. No patient had a complete response. 2 patients had a partial response, and the objective response rate was 18.2%. 5 patients were evaluated as stable disease with a disease control rate of 63.6%. The median overall survival and progression-free survival was 3.0 months and 2.3 months, respectively. A patient with partial response had a long duration of response of 5.2 months. The most common grade 3 or 4 treatment-related were neutropenia, anemia, and decreased neutrophil count. Most immune-related adverse events were grade 1 or 2, with rash, pruritus and hypothyroidism being the most common, and 1 patient had grade 3 pneumonia. Conclusions: Immunotherapy plus chemotherapy could be beneficial for a subgroup of extensive-stage SCLC patients who have progressed after previous chemotherapy. Further prospective, randomized studies are warranted.