PTGS2 and Patent ductus arteriosus: Targeting MDSCs along with a cancer antigen greatly improves the efficacy of the cancer vaccine (46, 47) and in this regard, we have previously reported that simultaneous targeting of MUC1 and COX-2 in a spontaneous model of PDA was highly effective in stalling the progression of PanIN lesions to adenocarcinomas and in inhibiting invasive disease (48).