Abstract IA23: Immune landscape of human pancreatic cancer

Abstract

Abstract Survival rates for pancreatic ductal adenocarcinoma (PDA) remain dismal. Immunotherapy has the potential to improve outcomes, but clinical trial results – particularly those employing single-agent CTLA4 or PD1/PD-L1 inhibition – have thus far been disappointing. We stratified human PDA based on a signature of cytolytic T-cell activity. Differences in cytolytic index correlated with defined PDA subtypes and distinct mutational events. Specifically, PDA tumors with low cytolytic activity exhibited increased genomic structural variation, including reproducible copy number alterations in MYC, FGFR1, NOTCH2, and CDKN2. In contrast to other tumors such as kidney cancer or melanoma, PDA tumors with a high cytolytic index lacked an increased mutation or neo-epitope load. Tumors with high cytolytic activity exhibited increased expression of several immune checkpoint genes, but PD-L1 expression was uniformly low. These data establish a link between genomic alterations and immune activation in PDA and suggest that immune checkpoints other than PD-L1/PD-1 may be attractive therapeutic targets in this lethal disease. Citation Format: David Balli, Andrew J. Rech, Ben Z. Stanger, Robert H. Vonderheide.{Authors}. Immune landscape of human pancreatic cancer. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr IA23.