Efficacy of carboplatin-etoposide rechallenge after first-line chemo-immunotherapy in ES-SCLC: an international multicentric analysis.

Background and objectives: Second-line treatment for small-cell lung cancer (SCLC) is primarily guided by the time elapsed since the last platinum dose. Rechallenge with carboplatin and etoposide has demonstrated superior outcomes compared to topotecan if the platinum-free interval (PFI) is longer than 90 days and is considered the standard of care. However, these findings predate the chemo-immunotherapy era. This study investigates the effectiveness of the rechallenge strategy after chemo-immunotherapy in a real-world setting. Design and methods: We retrospectively reviewed patients with the extensive stage (ES)-SCLC who received rechallenge with carboplatin and etoposide after first-line chemoimmunotherapy between September 2020 and August 2023 in nine European centres. Demographic and clinical data were collected and analysed. Results: A total of 93 patients were included. Sixty-six (71%) patients had a PFI between 3 and 6 months. Consolidation thoracic radiotherapy and prophylactic cranial irradiation had been administered in 31 (33.3%) patients and 20 (21.5%) patients, respectively. Overall response rate was 59.1%. Median progression-free survival (PFS) was 5 months (95% confidence interval (CI) 4.3-5.7) and median overall survival (OS) was 7 months (95% CI 5.7-8.3). Notably, PFS and OS were not different according to PFI (3-6 m vs > 6 m). Conclusion: Rechallenge with carboplatin and etoposide is a valid second-line option in patients with ES-SCLC whose disease progresses after first-line chemoimmunotherapy. Our analysis shows similar results to previous studies. Furthermore, outcomes were consistent across patients with different PFIs, confirming its efficacy in patients with a PFI longer than 3 months.