PDCD1 and neoplasm: In line with this notion, a PI3Kγ inhibitor (TG100‐15) markedly enhances the tumour suppressive effects of anti‐PD1 antibody in a mouse model of head and neck squamous carcinoma.46 In the mammary tumours developed in polyoma middle T oncogene (PyMT) transgenic mice, a selective class IIa histone deacetylase inhibitor (TMP195) alters predominant macrophage populations in the tumour from TAM to highly phagocytic macrophages.