PDCD1 and colonic neoplasm: Furthermore, an in vivo study using a murine colon cancer model (MC38 cells stably expressing human CEA; MC38.CEA) showed that PEG-MP7 effectively inhibited PD-1: PD-L1 interaction, showing efficacy equal to anti-PD-1 antibody in suppressing PD-L1+ carcinoma cell growth.