Dynamic Changes in Blood PD-L1 Expression Predict the Efficacy and Overall Survival of Immune Checkpoint Inhibitor Treatment in Non-Small-Cell Lung Cancer Patients

Abstract Background Immune checkpoint inhibitors (ICIs) have become a high-profile treatment regimen for malignancy in recent years. However, only a small piece of patients obtain benefit. How to use reasonable biomarkers to optimally select suitable patients is currently a research hot topic.Methods Paired tissue samples and blood samples from 51 patients with various malignancies were collected for correlation analysis. Dynamic changes in bPD-L1 expression, including PD-L1 mRNA, soluble PD-L1 (sPD-L1) and exosomal PD-L1 (exoPD-L1) protein, were detected in non-small-cell lung cancer (NSCLC) patients treated with ICIs. The best cutoff values for progression-free survival (PFS) and OS of all three biomarkers were calculated with R software.Results In 51 malignancies patients, those with positive tPD-L1 expression had significantly higher PD-L1 mRNA expression than those with negative tPD-L1 expression. For sPD-L1 expression, only the TC1~2/IC1~2 group had higher expression than the TC0/IC0 group. In 40 NSCLC patients, those with a fold change (2 months compared to baseline) of PD-L1 mRNA over 2.03 had a better PFS, a better OS and the best objective response (bOR) rate. In addition, a fold change of exoPD-L1 over 1.85 was also found to be associated with better efficacy and OS in a small cohort. Furthermore, the combination of the biomarkers could better screen patients who could benefit from ICI treatment.Conclusion Blood PD-L1 expression was positively correlated with tPD-L1 expression. Increased expression of exoPD-L1, PD-L1 mRNA, or both during early treatment could serve as biomarkers for predicting efficacy and OS in NSCLC patients treated with ICIs.