Programmed death 1 (PD-1) lymphocytes and ligand (PD-L1) in colorectal cancer and their relationship to microsatellite instability status


Zoran Gatalica, Carrie L. Snyder, Kimberly Yeatts, Nianqing Xiao, Daniel Holterman and Henry T. Lynch


PD-1 activation by its ligands (PD-L1 and PD-L2) inhibits T-cell activation and plays a role in cancer progression. PD-L1 is widely expressed in many cell types in tumor microenvironment. In contrast, expression of PD-1 is restricted to a small subset of T-lymphocytes. Inhibition of PD-1/PD-L1 interaction showed no benefit in a small number of colorectal cancers studied in clinical trials. We investigated tumor infiltrating PD-1+lymphosytes and PD-L1 expressing cells in CRC to gain insight in their role as biomarkers.

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