261 Synergistic antitumor effects of mouse mesothelin-directed CAR (mmeso-CAR) T cells and αCD40 in a syngeneic model of PDAC by Carl H June, John Scholler, Joseph A Fraietta, Andrew Rech, Daniel Martinez, David Mai, Omar Johnson, Khatuna Gabunia, Regina M Young, Charles-Antoine Assenmacher, Enrico Radaelli, Giulia Golinelli, Ting-Jia Fan, Jordan Reff, Zachary Ferraro, Decheng Song, Aasha Gupta, Mansi Deshmukh, He N Xu, Wesley V Wilson, Julia C Tchou, Bruce L Levine