Celecoxib not only hinders the proliferation and metastasis of tumor cells by inhibiting COX-2 synthesis, but also inhibits the intratumoral infiltration of regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) and activates cytotoxic T cells, thereby reshaping the inhibitory immune microenvironment. The gene discussed is PTGS2; the disease is neoplasm.