Prognostic significance of PD-1/PD-L1 expression in uveal melanoma: correlation with tumor-infiltrating lymphocytes and clinicopathological parameters

Singh, L.; Singh, M.K.; Kenney, M.C.; Jager, M.J.; Rizvi, M.A.; Meel, R.; Lomi, N.; Bakhshi, S.; Sen, S.; Kashyap, S.

doi:doi:10.1007/s00262-020-02773-8

BackgroundTo understand how to improve the effect of immune checkpoint inhibitors in uveal melanoma (UM), we need a better understanding of the expression of PD-1 and PD-L1, their relation with the presence of tumor-infiltrating lymphocytes (TILs), and their prognostic relevance in UM patients. Materials and methodsExpression of PD-1 and PD-L1 was assessed in 71 UM tissue samples by immunohistochemistry and quantitative real-time PCR (qRT-PCR), and further validated by western blotting. The effect of interferon gamma (IFN-gamma) on PD-1/PD-L1 expression was determined on four UM cell lines. ResultsImmunoreactivity of PD-1 was found in 30/71 cases and of PD-L1 in 44/71 UM samples. Tumor-infiltrating lymphocytes were found in 46% of UM tissues. PD-1 was expressed on TILs while tumor cells expressed PD-L1. UM with and without TILs showed expression of PD-1 in 69% and 18% cases, respectively (p=0.001). Similarly, PD-L1 was found in 75% of UM with TILs and in 50% of cases without TILs,...Show moreBackgroundTo understand how to improve the effect of immune checkpoint inhibitors in uveal melanoma (UM), we need a better understanding of the expression of PD-1 and PD-L1, their relation with the presence of tumor-infiltrating lymphocytes (TILs), and their prognostic relevance in UM patients. Materials and methodsExpression of PD-1 and PD-L1 was assessed in 71 UM tissue samples by immunohistochemistry and quantitative real-time PCR (qRT-PCR), and further validated by western blotting. The effect of interferon gamma (IFN-gamma) on PD-1/PD-L1 expression was determined on four UM cell lines. ResultsImmunoreactivity of PD-1 was found in 30/71 cases and of PD-L1 in 44/71 UM samples. Tumor-infiltrating lymphocytes were found in 46% of UM tissues. PD-1 was expressed on TILs while tumor cells expressed PD-L1. UM with and without TILs showed expression of PD-1 in 69% and 18% cases, respectively (p=0.001). Similarly, PD-L1 was found in 75% of UM with TILs and in 50% of cases without TILs, respectively (p=0.03). DFS rate were lower in patients with TILs with expression of PD-1 and PD-L1, but the rate of DFS was higher with expression of PD-L1 in patients without TILs. After treatment of UM cell lines with IFN-gamma, PD-1 expression was induced in all UM cell lines whereas PD-L1 expression was found at a lower level in untreated cells, while expression also increased following treatment with IFN-gamma .ConclusionOur study suggests that increased infiltration with TILs promotes the aggressive behavior and suppresses the immune response of UM cells, thereby inhibiting immunotherapy.Show less

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Prognostic significance of PD-1/PD-L1 expression in uveal melanoma: correlation with tumor-infiltrating lymphocytes and clinicopathological parameters