PDCD1 and neoplasm: Huang et al observed that although the immune system responds with a PD-1+ CD8+ T-cell infiltration and an inflammatory response after a single dose of anti-PD-1 ICIs, the tumor develops resistance mechanisms of immune suppression and tumor evolution in response to treatment.39 Furthermore, it is likely that the role of these molecules is complex and depending on the cell environment, as it is the case for IL-10, an established immunosuppressive protein that has been demonstrated to induce a strong antitumor T-cell response in mice and humans.43 44