CTLA4 and cancer: Given the immunosuppressive role of PGE2 in cancer progression, a series of researches have provided evidence on the clinical beneficial of NSAIDs which inhibit increased COX activity and PGE2 production on tumor progression, particularly in a remarkable synergy between NSAIDs and CTLA-4 or PD-1 blockade immunotherapy results in tumor eradication [20, 26, 27].