Abstract 712: Immune checkpoint inhibitor induced tumor gene expression changes in murine syngeneic colon cancer models

Abstract

Abstract The success of immune checkpoint therapy with anti-PD-1 and anti-CTLA-4 antibodies has generated broad interest in immuno-based interventions for oncology. Preclinical efficacy assessment of these novel immune-oncology therapies requires a functional immune system and therefore is frequently performed in murine syngeneic tumor models. In addition to tumor growth inhibition, syngeneic tumor models provide a platform to investigate the mechanism of action for a given novel therapeutic target. Characterization and mechanism of action for immune-based cancer therapies in murine syngeneic tumor models is often assessed by flow cytometry; measuring changes in tumor infiltrating leukocyte (TIL) populations following treatment induction. We assessed whether transcriptomic gene expression analysis could identify additional relevant biomarkers for immunotherapy response. Mice bearing subcutaneous syngeneic colon cancer tumors were dosed intraperitoneally with either vehicle alone, anti-CTLA-4, anti-PD-1, or a combination of the two immune checkpoint inhibitors on days 1, 4, and 8. Tumors were harvested on day 9 and half from each group were assessed for TIL population composition by flow cytometry and half by Clariom D mouse transcriptome array analysis. We identified a number of immune cell-related genes with differential expression that correlated to the therapeutic response and were consistent with changes identified in TIL populations by flow cytometry. These results provide an additional metric for assessing immunotherapy response in vivo. In addition, these data suggest that a smaller, defined panel of gene targets may be developed as biomarkers for specific immune system responses to immune checkpoint therapies in murine syngeneic models. Citation Format: Patrick Fadden, Douglas Weitzel, Kelli Davis, Thi Bui, David Hurtado, Hannah Haines, Rhiannon Roark, Ashleigh Derrick, Beverly Godfrey, Ian Belle, Katherine Krontz, Cristina Sokolowski, Aidan Synnott, Edgar Wood. Immune checkpoint inhibitor induced tumor gene expression changes in murine syngeneic colon cancer models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 712.