PDCD1 and neoplasm: Approximately 80% of the recurrent/metastatic HNSCCs are resistant to ICI targeting the anti-PD-1/programmed death-ligand 1 (PD-L1) axis.4 5 There are many ways for the tumor to escape from antitumor immunity, such as directly suppressing antitumor immunity, hindering immune cell trafficking, hampering immune recognition by downregulating major histocompatibility complex class I molecules, or orchestrating a suppressive TIME.49 50 Protumorigenic macrophages play a central role in the latter.