EGFR and non-small cell lung carcinoma: Although there was no significant difference in the fraction of M2 macrophage between two groups, the ratio of M1/M2 was found to be markedly higher in PR group (P = 0.025; Fig. 4d), indicating the pivotal role of macrophage in determination of antitumor activity of PD-1 blockade plus chemotherapy in EGFR-mutant NSCLC.33