CD4 and metastatic malignant neoplasm: Previously, increased TNF‐α and IFN‐γ levels by PDT had been confirmed to create an immunogenic microenvironment against metastatic cancer.25 In addition, CD4+CD8+ double positive T lymphocytes were correlated with enhanced TNF‐α and IFN‐γ production.26 In contrary to CAH (+), PD‐1 induced an enhancement in IFN‐γ secretion but not TNF‐α.