We show here that COX2 expression at the tumor margin limits CD8+ T-cell infiltration into the tumor core, which involves at least in part reduced cytokine and chemokine expression (IRF8, CLEC9a, CXCL9, CXCL10, CXCL11, and IL27) that promotes directional immune cell migration. This evidence concerns the gene IL27 and neoplasm.