Especially, elevated Wnt signaling has been implicated in immunosuppressive phenotypes, including insufficient tumor infiltration of immune cells, upon which clinical response to CTLA-4 and PD-1/programmed cell death-ligand 1 (PD-L1) immune checkpoint inhibitors (e.g., ipilimumab and pembrolizumab) is dependent.17–20 Recent reports have shown that combining Wnt inhibitors with immuno-oncology (IO) therapies may have synergistic effects in preventing cancer progression.12 Here, PDCD1 is linked to cancer.