Atezolizumab plus chemotherapy for Asian vs. non-Asian patients with extensive-stage small-cell lung cancer: A propensity score matched pooled analysis of four phase 3 trials

Introduction Differences in tumor biology and microenvironment and immunological landscape mean race can impact cancer outcomes. We compared the efficacy and safety of first-line atezolizumab plus chemotherapy in Asian and non-Asian patients with extensive-stage small-cell lung cancer (ES-SCLC). Materials and Methods Data for patients who received ≥ 1 atezolizumab dose plus chemotherapy (carboplatin + etoposide) in IMpower133, SKYSCRAPER-02, SKYSCRAPER-02C, and BEAT-SC were pooled. Propensity score matching estimation by race (Asian, non-Asian) was the response variable. Endpoints included overall survival (OS), progression-free survival (PFS), and safety. Results There were 363 Asian and 344 non-Asian patients. Before matching, the Asian cohort had more males, never-smokers, and patients with Eastern Cooperative Oncology Group performance status 1; lower body mass index; and fewer patients with liver metastases. Median (95% confidence interval [CI]) OS for Asians and non-Asians was 15.3 (13.8, 16.6) and 12.2 (10.6, 13.5) months, respectively (hazard ratio [HR] [95% CI] 0.80 [0.67, 0.94]; p = 0.008). After matching, median (95% CI) OS and PFS for Asian versus non-Asian patients (both n = 169) were 16.4 (14.6, 18.8) versus 11.3 (9.6, 13.1) and 4.8 (4.3, 5.6) versus 5.1 (4.3, 5.6) months, respectively. Asian patients had longer OS (HR [95% CI], 0.70 [0.55, 0.89]; p = 0.004). Most patients had ≥ 1 adverse event (AE) (Asians, 98.8% and non-Asians, 100%), 82.8% and 60.9% had grade 3–4 AEs, and 0.6% and 4.7% had grade 5 AEs. Conclusion This analysis demonstrates the utility of atezolizumab plus chemotherapy for ES-SCLC and longer OS for Asian patients.