Abstract B039: T cell recruitment dynamics at different stages of primary and metastatic colorectal cancer

Abstract

Abstract Colorectal cancer (CRC) is the fourth deadliest cancer worldwide, primarily due to metastasis. The current standard therapy for patients with CRC includes neoadjuvant therapies combined with surgery, often resulting in severe complications that affect patients’ lifestyles. Hence, there is a critical need to improve our understanding of the tumor microenvironment to improve the current therapeutics for metastatic CRC. We characterized T cell dynamics in response to tumors at early (1-2 weeks) versus late stages (6-7 weeks) of CRC development in different colon compartments (tumor, epithelium, lamina propria), as well as in colon-draining lymph nodes and the liver as potential metastasis sites. To achieve this, we injected by colonoscopy tumor AKP mouse organoids (mutations in APC, Kras, and P53 genes) or metastatic AKP mouse organoids in the colon walls of a novel fate-mapping strain (iSell-tomato). This model allows for the labelling of peripheral T cells that are recruited to the tissue or tumor sites. Our initial data showed an enhanced recruitment of CD4 and CD8ab T cells to the colon epithelium in early stage AKP (non-metastatic) tumor models compared to late-stage AKP and metastatic-AKP models at both stages. These recruited cells exhibited an enhanced anti-tumorigenic profile characterized by the production of IFNg and reduced frequency of FoxP3+ CD4 regulatory T cells (Tregs). In contrast, T cells recruited to early stage metastatic-AKP tumors and late-stage tumors of the colon and liver exhibited enhanced exhaustion characterized by an increased frequency of PD1+ CD4 and CD8ab T cells. These data suggest a time- and aggressiveness-dependent effect of tumors on immune cell infiltrates that, in turn, affect tumor progression and metastasis. Citation Format: Marwa A Saad, Angelina Bilate, Daniel Mucida. T cell recruitment dynamics at different stages of primary and metastatic colorectal cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr B039.