PDCD1 and colorectal carcinoma: Interestingly, in early-stage pMMR colon cancer patients, high CD8+PD-1+ T cell infiltration in preoperative biopsies was a predictive factor for neoadjuvant immune checkpoint inhibitor treatment response [23] suggesting that a possible sub-group for immune checkpoint inhibitor treatment in pMMR CRC patients might lie in those with high T-cell infiltration.