Propensity score matched pooled analysis of four phase 3 trials of atezolizumab plus chemotherapy for ES-SCLC in Asian versus non-Asian patients

Differences in tumor biology and microenvironment and immunological landscape could cause race-based differences in cancer outcomes. Pooled analysis of four phase 3 trials (IMpower133, SKYSCRAPER-02, SKYSCRAPER-02C, and BEAT-SC) investigated first-line atezolizumab plus chemotherapy (carboplatin plus etoposide) for extensive-stage small cell lung cancer (ES-SCLC) in Asian and non-Asian patients. Endpoints were overall survival (OS), progression-free survival (PFS), and safety. There were 363 Asian and 344 non-Asian patients. Before matching, the Asian cohort had more males, never-smokers, and patients with ECOG performance status 1; lower body mass index; and fewer patients with liver metastases. Median OS was 15.3 months among Asian patients and 12.2 months among non-Asian patients (HR 0.80; p=0.008). After matching, in two groups of 169 patients each, median OS was 16.4 months among Asian patients and 11.3 months among non-Asian patients (HR 0.70; p=0.004), whereas median PFS was 4.8 versus 5.1 months. Most patients had at least one adverse event: Asians 98.8% versus non-Asians 100%; grade 3-4: 82.8% versus 60.9%, and grade 5: 0.6% versus 4.7%. The authors conclude that this analysis demonstrates longer OS with first-line atezolizumab plus chemotherapy for ES-SCLC in Asian versus non-Asian patients.