Towards a mechanistic understanding of response to SBRT by patients with borderline resectable pancreatic cancer

Five year survival rates for pancreatic cancer remain low, around 11%. We assessed differential gene expression between SBRT responders and non-responders as well as expression pre and post SBRT. Samples were obtained from the University of Colorado biorepository. All patients had borderline resectable pancreatic cancer, treated with neoadjuvant chemotherapy followed by restaging, and treatment with 30–33.6 Gy SBRT to pancreatic tumors, followed by pancreaticoduodenectomy and adjuvant chemotherapy. We observed increases in PDL1, PD1, CD25, and a decrease in CD122 expression following RT. Furthermore, we found that responders to SBRT exhibit decrased CD25 expression with increased CD122 and CD132 expression compared to non-responders. Using GSEA of responders vs. non-responders, we found responders to SBRT exhibit enrichment of inflammatory response, IFN signaling, and IL2/STAT5 signaling. Tumor tissue collected from patients at the time of initial biopsy (fine needle aspirate) and at time of surgery (post SBRT) were used for RNAs sequencing.