Real-World Long-Term Efficacy of Chemoimmunotherapy in Advanced Stage Small-Cell Lung Cancer

INTRODUCTION: Since IMpower133 and CASPIAN phase 3 trials, chemoimmunotherapy has become the first-line systemic treatment for advanced-stage small-cell lung carcinoma (SCLC). We conducted a study on the long-term efficacy. METHODS: A retrospective cohort study was performed on advanced-stage SCLC patients who initiated treatment with first-line carboplatin-etoposide-atezolizumab between January 2018 and December 2022 at the University Hospitals Leuven. Follow-up data were collected until February 2025. The Kaplan-Meier method was used for estimating survival outcomes, and Cox regression models were used to assess the association between baseline clinical characteristics (age, ECOG Performance Status, metastatic sites, s-albumin, s-lactate dehydrogenase, s-C-reactive protein, s-NSE, neutrophil-lymphocyte ratio [NLR], modified Glasgow Prognostic Score [mGPS], and Lung Immune Prognostic Index [LIPI] score) and survival outcomes. RESULTS: A total of 74 patients were included. The median progression-free survival (PFS) was 4.8 months (95% CI: 4.5-5.0), and median overall survival (OS) was 11.5 months (95% CI: 8.9-14.6). The 1-, 2-, and 5-year PFS and OS rates were 16.2% (95% CI: 8.9-25.5), 9.5% (95% CI: 4.2-17.4), and 8.1% (95% CI: 3.3-15.7) and 47.3% (95% CI: 35.6-58.1), 18.9% (95% CI: 11.0-28.5), and 8.9% (95% CI: 3.2-18.2%), respectively. In multivariable analysis, bone metastasis (HR 2.21; 95% CI: 1.26-3.87), age (+1 year, HR 1.03; 95% CI: 1.00-1.07), s-NSE >250 μg/L (HR 4.55; 95% CI: 2.13-9.72), and s-albumin ≥35 g/dL (HR 0.49; 95% CI: 0.25-0.99) were significantly associated with OS. During induction phase, chemotherapy dose reduction and discontinuation occurred in 31% and 8%, respectively. Overall, immune-related adverse events occurred in 21 patients (28%), leading to discontinuation of atezolizumab in 7 patients (10%). CONCLUSION: Our study provides long-term safety and efficacy outcomes of first-line chemoimmunotherapy in a real-world cohort of advanced-stage SCLC. In multivariable analysis, we found that baseline conventional biomarkers (age, bone metastasis, s-albumin, and s-NSE) did significantly predict OS, while systemic inflammation scores (NLR, mGPS, and LIPI) did not.