CD8A and lung cancer: Tregs are believed to play an important role in tumor progression by maintaining an immune‐tolerant microenvironment and regulating T‐cell cytotoxicity.[33] High proportions of tumor‐infiltrating Tregs are recognized as negative prognostic factors in lung cancers,[34] while decreased ratios of CD8+ T cells/Treg cells are correlated with poor prognoses in patients with breast and gastric cancers.[35, 36] Thus, Treg regulatory pathways might provide novel treatment opportunities.