{
  "abstract": "Background Regulatory T cells (Tregs) are correlated with poor prognosis in multiple cancer types. 1 Therapies targeting self-specific thymically derived Tregs have shown promise; however, they can lead to systemic autoimmunity and inflammation.2 RORγt+ peripherally-induced Tregs (pTregs) are potently suppressive cells that differentiate from naïve CD4+ T cells and are specific to commensal microbes.3 Recent studies have shown the importance of pTregs in solid tumors outside the gut, including pro-tumorigenic functions distinct from tTregs.4–6 We aim to target RORγt+ pTregs independently from tTregs to promote anti-tumor immunity while preserving systemic self-tolerance. We hypothesize that RORγt supports pTreg suppressive function to promote tumor growth at sites distant from the colon.Methods We utilized a mouse model that allows the conditional deletion of RORγt in Foxp3 expressing cells upon tamoxifen treatment ( Foxp3 CreERT2 Rorc fl/fl). We tracked the growth of subcutaneous MC38 colon adenocarcinoma tumors in wildtype (WT) and tamoxifen-treated mice (TregΔRORγt). We used flow cytometry and single cell RNAseq to assess immune infiltration and function of tumor infiltrating lymphocytes. Finally, we used a mixed bedding technique to homogenize the microbiomes of male and female mice to assess the role of the microbiome on tumor growth in our model.Results Deletion of RORγt in Tregs led to decreased tumor growth specifically in male mice with no signs of detrimental systemic inflammation. Overall Treg numbers were decreased and IL-10 production was reduced in the tumor. Additionally, we saw increased T cell infiltration into the tumor. These T cells were more highly activated, maintained a progenitor-like state, and had increased production of proinflammatory cytokines compared to WT mice. However, these findings were not replicated in female Treg ΔRORγt mice, indicating a role for sex in our model. Strikingly, when microbiomes were normalized between males and females, TregΔRORγt female mice harboring a male microbiome showed reduced tumor growth, suggesting that male TregΔRORγt microbiome is sufficient to induce attenuated tumor growth.Conclusions Here, we have shown that targeting pTregs can efficiently promote anti-tumor immunity without leading to systemic inflammation. Additionally, our findings have highlighted the importance of sex and microbiome composition on anti-tumor immunity and suggests an interplay between the two factors to influence tumor growth at distant sites. Overall, these findings have the potential to identify novel pTreg targets that could enhance immunotherapy efficacy without detrimental toxicities or inflammation for patients.References Tanaka A, Sakaguchi S. Targeting treg cells in cancer immunotherapy. Eur. J. Immunol. 2019;49:1140–1146.Tay C, Tanaka A, Sakaguchi S. Tumor-infiltrating regulatory T cells as targets of cancer immunotherapy. Cancer Cell 2023;41:450–465Sefik E, Geva-Zatorsky N, Oh S, Konnikova L, Zemmour D, McGuire AM, Burzyn D, Ortiz-Lopez A, Lobera M, Yang J, et al. Individual intestinal symbionts induce a distinct population of RORγ+ regulatory T cells. Science 2015;349:993–997.Blatner NR, Mulcahy MF, Dennis KL, Scholtens D, Bentrem DJ, Phillips JD, Ham S, Sandall BP, Khan MW, Mahvi DM, et al. Expression of RORγt marks a pathogenic regulatory T cell subset in human colon cancer. Sci. Transl. Med. 2012;4:164ra159.Osman A, Yan B, Li Y, Pavelko K.D, Quandt J, Saadalla A, Singh M.P, Kazemian M, Gounari F, Khazaie K. TCF-1 controls Treg cell functions that regulate inflammation, CD8+ T cell cytotoxicity and severity of colon cancer. Nat. Immunol. 2021;22:1152-1162.6.Hossain MM, King P, Hackett J, Gerard H.C, Niwinski R, Wu L, Van Kaer L, Dyson G, Gibson H, Borowsky AD, et al. Peripheral-derived regulatory T cells contribute to tumor-mediated immune suppression in a nonredundant manner. Proc Natl Acad Sci USA. 2024;121:e2404916121.",
  "authors": [
    {
      "affiliations": [
        "Hillman Cancer Center, Pittsburgh, PA, USA",
        "University of Pittsburgh, Pittsburgh, PA, USA"
      ],
      "name": "Kelsey M Ertwine"
    },
    {
      "affiliations": [
        "University of Pittsburgh, Pittsburgh, PA, USA"
      ],
      "name": "Jessica A Jana"
    },
    {
      "affiliations": [
        "University of Pittsburgh, Pittsburgh, PA, USA"
      ],
      "name": "Kristin Morder"
    },
    {
      "affiliations": [
        "University of Pittsburgh, Pittsburgh, PA, USA"
      ],
      "name": "Dipyaman Patra"
    },
    {
      "affiliations": [
        "University of Pittsburgh, Pittsburgh, PA, USA"
      ],
      "name": "Katelyn Wolfgang"
    },
    {
      "affiliations": [
        "University of Pittsburgh, Pittsburgh, PA, USA"
      ],
      "name": "Abigail E Overacre-Delgoffe"
    }
  ],
  "title": "823 A small but mighty ROR(γt): RORγt supports peripherally induced regulatory T cell function and sex-dependent tumor growth",
  "uid": "6f4cfc2c-ab8e-56d4-b018-5f6745c66ee3"
}