Immunologic alterations in the pancreatic cancer microenvironment of patients treated with neoadjuvant chemo- and radiotherapy.

Pancreatic ductal adenocarcinoma (PDAC) has dismal S-year survival (<9%). We hypothesize that exposure of tumors to conventional therapies may preferentially modulate immune biomarkers in the tumor microenvironment in PDAC. PDAC patients who underwent upfront surgical resection or who received neoadjuvant FOLFIRINOX with or without neoadjuvant radiotherapy followed by surgical resection were selected for study. Total expression of immunologically relevant transcripts and spatially resolved expression of immunologically relevant proteins was quantitated using multiplexed methods (NanoString nCounter and GeoMX platforms). This analysis identified numerous differentially expressed transcripts associated with the type of neoadjuvant therapy received. Moreover, we identified significant alterations in the expression and/or spatial distribution of immunologically relevant proteins in different regions (tumor cell rich, immune cell rich, stromal cell rich) of the tumor microenvironment. These data provide insight into the immunological effects of clinically relevant neoadjuvant therapy for resectable/borderline-resectable PDAC by describing significant differences in the expression of key immunologic biomarkers within the PDAC microenvironment that were associated with the type of treatment patients received prior to surgical resection. This represents a comprehensive analysis of numerous biomarkers conducted on the PDAC microenvironment. This work may guide strategic new combination therapies for pancreatic cancer.