PD-L1 expression in colorectal cancer and its relationship with TLR-4 expression.

Purpose: Expression of programmed death ligand-1 (PD-L1) is related to the prognosis of many solid tumors, but the prognostic value of PD-L1 expression in colorectal cancer (CRC) remains unclear. The aim of this study was to clarify the role of PD-L1 expression in predicting prognosis, and then provide further insight into the relation between PD-L1 and toll like receptor-4 (TLR-4) in CRC progression. Methods: The expression of PD-L1 and TLR-4 in patients with resected CRC was analyzed using immunohistochemistry (IHC). The biological relation of PD-L1 and TLR-4 in CRC was explored using gene set enrichment analysis (GSEA). Results: Positive PD-L1 and TLR-4 expression in tumor cells were observed in 12.7% and 41.2% respectively. High PD-L1 and TLR-4 expression levels were significantly correlated with poor disease-free survival. PD-L1 expression was closely associated with TLR-4 expression. Multivariate analyses further confirmed that increased expression levels of PD-L1 are unfavorable prognostic factors for operable CRC. Conclusion: High PD-L1 expression can be used as a prognostic indicator for patients with operable CRC. PD-L1 expression is associated with TLR-4 expression, thereby providing a theoretical basis for the combined use of PD-1/PD-L1 inhibitors and TLR agonists.