PDCD1 and neoplasm: In recent years, M2-type TAMs have also been shown to be strongly associated with weaker immunotherapeutic efficacy and other adverse clinical outcomes, such as drug resistance in patients during anti-PD-1/PD-L1 immunotherapy.267 Therefore, the activation of M1-type TAMs with antitumor activity, or the promotion of TAM polarization to the antitumor type, can enhance the ability of TAMs to phagocytose and kill tumor cells.