Given that the complex biology of TAMs and their involved role in tumor proliferation, angiogenesis, EMT, metastasis, immune suppression, TAMs have a multichannel inhibitory effect on anti-PD-1/PD-L1 immunotherapy (Weiskopf and Weissman, 2015; Villanueva, 2017), so that a single ICI (Immune checkpoint inhibitor) cannot effectively activate the immune response. The gene discussed is PDCD1; the disease is neoplasm.