It is known that a tumor at least has two well documented immune escape mechanisms to become resistant to anti-PD1 treatment: lack of CD8+ T-cell infiltration and CD8+ T-cell dysfunction (Sharma et al., 2017; Sade-Feldman et al., 2019; Yost et al., 2019; Wu et al., 2020). Here, PDCD1 is linked to neoplasm.