Abstract 2873: Neurotensin suppresses anti-tumor immunity and is associated with poor prognosis in colorectal cancer

Abstract Introduction. Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide with substantial heterogeneity in patient outcomes. Neurotensin (NTS) and its high-affinity receptor (NTSR1) have been implicated in CRC progression, particularly in modulating tumor metabolism and immune responses. NTS secretion increases under psychological stress and high-fat intake. Given the widespread expression of NTSR1 on immune cells, we hypothesized that NTS modulates anti-tumor immunity in CRC. The purpose of our current study was to integrate clinical, in vivo, and functional evidence to delineate the impact of NTS on immune responses and patient outcomes. Methods. (i) Clinical survival: Overall survival (OS) was analyzed in a single-institution CRC cohort (University of Kentucky; n=196) stratified by tumor NTS expression, and findings were validated using KMplot (n=1,061). (ii) Transcriptomic correlation: Correlations between NTS and immunosuppressive genes (e.g., IL10, ENTPD1) were assessed utilizing publicly available datasets (GEPIA/TCGA). (iii) In vivo: Murine CRC cells (MC38) were implanted subcutaneously into NTS wild-type (NTSWT) and NTS knockout (NTSKO) mice to compare tumor growth. Tumor-infiltrating immune cells and granzyme B (GZMB) expression were quantified by immunohistochemistry (IHC) and flow cytometry. (iv) In vitro cytotoxicity: MC38 cells were co-cultured with spleen-derived CD8+ T cells from MC38-primed mice, with or without NTS treatment, and cytotoxicity was measured by LDH release. Results. (i) High NTS expression was associated with shorter OS in the institutional cohort (P<0.05) and was validated in the KMplot dataset (n=1,061; P<0.001). (ii) NTS expression showed significant positive correlations with multiple immunosuppressive genes, including IL10 (P=0.0038) and ENTPD1 (P=0.046). (iii) In vivo, NTSKO mice exhibited markedly slower tumor growth, with increased immune-cell infiltration and higher intratumoral GZMB expression. (iv) In vitro, NTS treatment significantly reduced CD8+ T-cell cytotoxicity against MC38 cells, as indicated by decreased LDH release, supporting a direct suppressive effect of NTS on effector T-cell function. Conclusions. High NTS expression identifies CRC patients with poorer prognosis and functionally suppresses anti-tumor immunity by limiting CD8+ T-cell infiltration and cytotoxic activity. Interventions that lower NTS (e.g., stress reduction and dietary optimization) may improve responses to immunotherapy and clinical outcomes. These findings provide a biological rationale for targeting the NTS/NTSR1 axis in combination with immunotherapeutic strategies. Citation Format: Haoming Wu, Yang Wang, Dana Napier, Hong Jiang, Dong Li, Jing Li, B. Mark Evers, . Neurotensin suppresses anti-tumor immunity and is associated with poor prognosis in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 2873.