Post‐progression survival after atezolizumab plus carboplatin and etoposide as first‐line chemotherapy in small cell lung cancer has a significant impact on overall survival

BACKGROUND: The effect of first‐line chemotherapy on overall survival (OS) may be significantly influenced by subsequent therapy for patients with extensive disease small cell lung cancer (ED‐SCLC). Therefore, we evaluated the relationship between progression‐free survival (PFS), post‐progression survival (PPS), and OS of ED‐SCLC patients treated with atezolizumab plus carboplatin and etoposide as first‐line therapy. METHODS: We analyzed the data of 57 patients with relapsed ED‐SCLC treated with atezolizumab plus carboplatin and etoposide (AteCE) as first‐line chemotherapy between August 2019 and September 2020. The respective correlations between PFS‐OS and PPS‐OS following first‐line AteCE treatment were examined at the individual patient level. RESULTS: Spearman's rank correlation analysis and linear regression analysis showed that PPS strongly correlated with OS (r = 0.93, p < 0.05, R ( 2 ) = 0.85) and that PFS moderately correlated with OS (r = 0.55, p < 0.05, R ( 2 ) = 0.28). Performance status at relapse (0–1/≥2), number of cycles of atezolizumab maintenance therapy (<3/≥3), and platinum rechallenge chemotherapy all significantly positively correlated with PPS (p < 0.05). CONCLUSIONS: Upon comparing OS‐PFS and OS‐PPS in this patient population, OS and PPS were found to have a stronger correlation. These results suggest that performance status at relapse, atezolizumab maintenance, or chemotherapy rechallenge could affect PPS.