Cellular localization of PD-L1 expression in mismatch-repair-deficient and proficient colorectal carcinomas.
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ABSTRACT: Blockade of the interaction between PD-1 and its ligands PD-L1 has shown clinical efficacy across several tumor types, especially in mismatch-repair-deficient colorectal carcinoma. The aim of this study was to examine the pattern and cellular localization of PD-L1 expression in the different molecular subtypes of mismatch-repair-deficient colorectal cancers vs. their mismatch-repair-proficient counterparts. PD-L1/SATB2 double-antibody-immunohistochemistry was utilized to distinguish tumor cell from immune cell staining. We observed in our series of 129 colorectal adenocarcinomas that PD-L1 expression occurred primarily in tumor-associated-immune cells and most prominently at the tumor-stroma-interface of the invasive front. The level of invasive front immune cell staining was significantly higher in mismatch-repair-deficient tumors compared to mismatch-repair-proficient tumors (p?=50% of the tumor). These findings may serve to inform further efforts aiming to evaluate PD-L1 immunohistochemistry vis-à-vis molecular sub-classification as predictive biomarkers in the treatment of colorectal carcinoma.
SUBMITTER: Liu S
PROVIDER: S-EPMC6309293 | biostudies-literature | 2019 Jan
REPOSITORIES: biostudies-literature
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