[Expert consensus on PD-L1 expression testing in non-small-cell lung cancer in China]

Cancer immunotherapy, especially the programmed death 1 (PD-1) and (or) programmed death ligand 1 (PD-L1) checkpoint inhibitors, has ushered in the modern oncology era and has achieved impressive success in the treatment of different tumors, including non-small-cell lung cancer (NSCLC). Yet, only a subset of patients achieved clinical benefit. Therefore, how to effectively screen the potential beneficiaries of PD-1 and (or) PD-L1 inhibitors has become a new challenge in the era of cancer immunotherapy. Clinical studies have shown that the expression level of PD-L1 in NSCLC is positively correlated with the efficacy of PD-1 and (or) PD-L1 inhibitors, and is one of the important predictive biomarkers. However, there are many challenges in PD-L1 testing. With the approving of various PD-1 and (or) PD-L1 inhibitors for immunotherapy setting of NSCLC, expert consensus of important issues regarding clinical significance of PD-L1 testing, testing time-point, as well as the standardization of PD-L1 testing procedure, including the PD-L1 testing operation steps, results' interpretation, quality control and so on, is of great significance for improving the accuracy of detection and reducing the difference between laboratories. On account to the practical questions of PD-L1 testing, this consensus was finally reached, which is based on the combination of literature, expert experience and internal discussion among committee members, in the hope of providing the guide for standardizing the PD-L1 testing and providing accurate and reliable result to screen the potential patients and predict clinical efficacy. It must be pointed out that in view of the existence of objective and complex factors of PD-L1 testing and the fact that the clinical application of PD-L1 testing is still at the early stage in China, there are still many issues need to be updated in near future based on further practice experience and research data.