PTGS2 and colon carcinoma: This has also been demonstrated in experimental models of ovarian and colon carcinomas, which showed that the COX-2/PGE2 axis excludes T cells from the tumor milieu and that blockade of COX-2 or PGE2 increases the number and the cytotoxic effects of CD8+ T cells, which boosted the efficacy of anti-PD-1 therapy [97,98].