PD-L1 expression and Tumor mutation burden as Pathological response biomarkers of Neoadjuvant immunotherapy for Early-stage Non-small cell lung cancer: A systematic review and meta-analysis.

To date, there is no approved biomarker for predicting pathological response in neoadjuvant programmed cell death (ligand) 1 (PD-(L)1) blockades treated early-stage non-small cell lung cancer (NSCLC). Databases including PubMed, Embase, ClinicalTrials.gov, and Conference abstracts were searched for clinical trials of neoadjuvant PD-1/PD-L1 blockades for resectable NSCLC. Data regarding major pathological response (MPR), pathological complete response (pCR) in patients with high/low pretreatment PD-L1 expression, and tumor mutation burden (TMB) were synthesized using fixed-model meta-analysis and evaluated by odds ratio with 95 % confidence interval. This analysis included 10 studies involving 461 NSCLC patients. Compared with PD-L1 expression <1%, PD-L1 expression ≥1% is associated with a higher rate of MPR and pCR. High-TMB associated with MPR and pCR. Similar findings were observed in subgroup analyses despite mono-PD-1/PD-L1 blockade or their combination with chemotherapy. Notably, 50 % as the cutoff value for PD-L1 expression demonstrated better prediction efficacy for MPR than that of 1%.