Efficacy and safety of atezolizumab, in combination with etoposide and carboplatin regimen, in the first-line treatment of extensive-stage small-cell lung cancer: a single-center experience

Background: Patients with small-cell lung cancer (SCLC) have a dismal prognosis with limited overall survival (OS) despite a high response rate to chemotherapy. Recently, immune checkpoint inhibitors, combined with chemotherapy, as the first-line treatment for extensive-stage (ES)-SCLC have shown improvement in clinical outcomes. Patients and methods: Real-world data from 68 Korean ES-SCLC patients, treated with atezolizumab, etoposide, and carboplatin at Yonsei Cancer Center between June 2019 and November 2020, were retrospectively analyzed to determine safety and efficacy using Cox regression analysis. Results: The median follow-up was 11.6 months. The median progression-free survival was 4.6 months (95% confidence interval [CI] 4.0–5.2), and the median OS was 12.0 months (95% CI 7.4–16.6). Baseline bone metastasis, immune-related adverse events (IRAEs), and elevated LDH were related to OS (hazard ratio 2.18, 0.33, and 4.64; P = 0.05, 0.02, and 0.003, respectively). Among the 42 patients with disease progression, liver metastasis progression and baseline bone metastasis were associated with inferior OS, but without statistical significance (hazard ratio 2.47 and 1.97; P = 0.25 and 0.26, respectively). Overall, 61 (89.7%) patients experienced treatment-related adverse events (TRAEs), with hematologic toxicities as the most common grade 3–4 TRAEs. Twenty-two (32.4%) patients experienced IRAEs, with skin rash as the most common, and five (7.4%) patients had grade-3 IRAEs (pneumonitis, hyperglycemia, and aspartate aminotransferase elevation). Conclusion: Atezolizumab, combined with etoposide and carboplatin, showed efficacy and safety in our real-world data. Further studies are needed to predict the response to immunotherapy in SCLC.