CD4 and neoplasm: Pretreatment tumor tissues from female patients had markedly lower tumor mutation and neoantigen burden, but significantly higher CD4, CD4/FOXP3, and CD4/FOXP3/PD‐L1 expression level than male patients, suggesting sex‐based neoantigen burden and immune microenvironmental feature heterogeneity would orchestrate the response to first‐line PD‐1 blockade plus chemotherapy in advanced NSCLC.