Definition of a new blood cell count (BCT) score for early survival prediction for non-small cell lung cancer patients treated with atezolizumab: Integrated analysis of 4 multicenter clinical trials

Introduction Immune checkpoint inhibitor (ICI) therapy is a major breakthrough in non-small cell lung cancer (NSCLC) treatment. However, valid predictive biomarkers are lacking. Blood cell count test (BCT) provides a direct quantification of various types of immune cells (ICs) to reveal the immune landscape to predict ICI treatment. Methods This study analyzed four international, multi-center clinical trials (OAK, BIRCH, POPLAR and FIR trials) to conduct post-hoc analyses of NSCLC patients undergoing atezolizumab (anti-PD-L1) single-agent treatment (n = 1,479) or docetaxel single-agent treatment (n = 707). BCT was conducted at three timepoints: pre-treatment (T1), the first day of treatment cycle 3 (T2), and first day of treatment cycle 5 (T3). Univariate and multivariate Cox regression analyses were conducted to identify early BCT biomarkers to predict atezolizumab treatment outcomes in NSCLC patients. Results The BCT biomarkers of neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) at timepoint T3 and neutrophil-to-monocyte ratio (NMR) at timepoint T2 were identified as strong predictive biomarkers for atezolizumab (Ate)-treated NSCLC patients in comparison to docetaxel (Dtx)-treated patients regarding overall survival (OS) (BCTscore low-risk: HR Ate vs Dtx = 1.54 (95% CI: 1.04-2.27), P = 0.036; high-risk: HR Ate vs Dtx = 0.84 (95% CI: 0.62-1.12), P = 0.236). This identified BCTscore model showed better OS AUC in the OAK (AUC 12month =0.696), BIRCH (AUC 12month =0.672) and POPLAR+FIR studies (AUC 12month =0.727) than that of each of the three single BCT biomarkers. Conclusion The BCTscore model is a valid predictive and prognostic biomarker for atezolizumab-treated NSCLC patients.