ABSTRACT
Immune checkpoint inhibitors (ICI) have transformed the treatment landscape of advanced non-small cell lung cancer (NSCLC). Biomarkers are essential for guiding precision immunotherapy. Tissue-based programmed death ligand 1 (PD-L1) expression and tumor mutational burden (TMB) are currently widely used biomarkers for selecting patients for immunotherapy. However, tissue specimens are often difficult to reach and couldn't overcome spatial and temporal heterogeneity. Blood biomarkers offer an alternative non-invasive solution that could provide a complete insight on patient's immune status and tumor as well, and show their potential in predicting the outcome as well as in monitoring response to immunotherapy. In this article, we summarize current knowledge on blood biomarkers in NSCLC patients treated with ICI, and we hope to provide more references for development of novel biomarkers. .