1473 Prostaglandin E2 and the tumor microenvironment: unleashing the potential of cancer immunotherapy through rational combination therapies by Anais Elewaut, Guillem Estivill, Maria Novatchkova, Felix Bayerl, Lisa Hoffmann-Haas, Francesco Andreatta, Trung Nguyen, Milica Vulin, Jan Boettcher, Anna Obenauf