Clinical outcomes of atezolizumab in combination with etoposide/platinum for treatment of extensive-stage small cell lung cancer: A real-world, multicenter, retrospective, controlled study in China

Objective: Atezolizumab along with chemotherapy has prolonged the survival of patients with extensive-stage small-cell lung cancer (ES-SCLC) worldwide, although real-world (RW) data are lacking in China. This study was designed to evaluate the efficacy and clinical outcomes of atezolizumab plus etoposide/platinum (EP). Methods: EP alone, we primarily evaluated progression-free survival (PFS); other efficacy indicators, including overall survival (OS), objective response rate (ORR), and patterns of SCLC progression and adverse events (AEs) were assessed. Results: The primary analysis included data from 225 patients, of whom 133 received EP along with atezolizumab (atezolizumab group) and 92 received EP alone (EP group). The PFS duration of the atezolizumab group [7.10 months; 95% confidence interval (95% CI), 6.53-9.00] exceeded that of the EP group (6.50 months; 95% CI, 4.83-7.53). Overall, the hazard ratio (HR) was 0.69 (95% CI, 0.49-0.97) (P=0.029); particularly, the HR was 0.54 (95% CI, 0.36-0.80) among patients undergoing ≥4 chemotherapy cycles and 0.33 (95% CI, 0.20-0.56) among individuals with atezolizumab maintenance. The ORR and disease-control rate (DCR) were similar between the two groups. Because of incomplete OS data, the median OS was not determined for either group. Bone marrow suppression was the most common AE detected (58.6%) in the atezolizumab group. Immune-related AEs occurred in 19 patients in the atezolizumab group (14.3%), with only one case of grade 3 encephalitis. Conclusions: This RW study in China demonstrated improved clinical outcomes of atezolizumab along with EP for ES-SCLC, particularly in the chemosensitive population. These results align with the results of the IMpower133 study, although the impact of this treatment modality on OS warrants additional follow-up studies.