Abstract 2696: Targeting SLC7A11 creates a favorable immune microenvironment in colorectal cancer

Abstract Background: Cysteine is a key immunoregulatory nutrient in colorectal cancer (CRC). Cystine uptake is primarily mediated by the cystine/glutamate transporter SLC7A11, which consists of 12 transmembrane α-helices that forming a channel through the cell membrane. Given SLC7A11’s role in both metabolic competition and resistance to ferroptosis, we aim to explore whether SLC7A11 can be effectively targeted with monoclonal antibodies as a therapeutic strategy for colorectal cancer. Methods: Using a cell-based in vivo immunoassay and standard hybridoma technology, we generated a human SLC7A11-specific murine monoclonal antibody, designated 1A4. Subcutaneous and orthotopic colorectal cancer models in mice, as well as an AOM/DSS-induced colitis-associated colorectal cancer model was established. We evaluated the effects of the SLC7A11 antibody on the immune microenvironment of colorectal cancer by multicolor immunofluorescence and flow cytometry. Furthermore, single-cell sequencing was employed to analyze alterations in immune cell subpopulations and to investigate the impact of the SLC7A11 antibody on immune cell metabolism and intercellular interactions within the tumor microenvironment. Flow cytometry was further utilized to validate the differential effects of the SLC7A11 antibody on CD4+ and CD8+ T cells. Results: Subcutaneous and orthotopic cancer model of colon cancer showed that treatment with 1A4 significantly reduced tumor volume. Multiplex immunofluorescence analysis showed that both duel immune checkpoint blockade and 1A4 increased the number of infiltrating CD8+ T cells and the CD8+T/Treg ratio in tumor tissues, with a more pronounced increase observed in tumors treated with 1A4. Single-cell sequencing results demonstrated that 1A4 modulated the tumor immune microenvironment by increasing the infiltration of T cells, B cells, and NK cells within the tumor tissue. RNA sequencing on CD4+ T cells exhibited more pronounced alterations in metabolic pathways. The flow cytometry results showed that treatment of CD8+ T cells with 1A4 enhanced stemness and a reduction in the proportion of exhausted CD8+ T cells. Conclusions: This study developed an antibody targeting the SLC7A11 and validated its anti-tumor effects in colorectal cancer. Targeting SLC7A11 potently creates a favorable immune microenvironment through inhibiting the activation of Tregs and increasing the stemness of CD8+ T cells. Citation Format: Jichang Li, Xiaoxue Pan, Kang Xia, Zeruo Yang, Xiaojing Yang, Pengyuan Wang, Shanwen Chen. Targeting SLC7A11 creates a favorable immune microenvironment in colorectal cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 2696.