Clinical and Molecular Predictors of PD-L1 Expression in Non-Small-Cell Lung Cancer: Systematic Review and Meta-analysis.

Clinicopathologic and molecular characteristics of non-small-cell lung cancers (NSCLCs) associated with a strong expression of programmed death ligand 1 (PD-L1 in > 5% of cells) have not been well elucidated. Expression of PD-L1 is a poor prognostic factor, but NSCLCs with higher levels of PD-L1 have greater benefit when treated with immunotherapy. We have performed a systematic review to synthesize the available evidence regarding clinicopathologic and molecular variables associated with PD-L1 expression in NSCLC.