Therefore, our findings showing enrichment of M2 macrophages in PD tumors, especially those expressing PD-L1, provide novel insights into the immune evasion mechanism of tumors associated with resistance to cetuximab-based treatments based on the differential dynamic features of tumors that eventually progress during cetuximab-based treatment and those maintaining anti-tumor activity (i.e., SD or PR). The gene discussed is CD274; the disease is neoplasm.