Cell-mediated Antitumor Immunity Research Articles

Inhibition of O-GlcNAc transferase activates type I interferon-dependent antitumor immunity by bridging cGAS-STING pathway.

The O-GlcNAc transferase (OGT) is an essential enzyme that mediates protein O-GlcNAcylation, a unique form of posttranslational modification of many nuclear and cytosolic proteins. Recent studies observed increased OGT and O-GlcNAcylation levels in a broad range of human cancer tissues compared to adjacent normal tissues, indicating a universal effect of OGT in promoting tumorigenesis. Here, we show that OGT is essential for tumor growth in immunocompetent hosts by repressing the cyclic GMP-AMP synthase (cGAS)-dependent DNA sensing pathway. We found that deletion of OGT (Ogt -/- ) caused a marked reduction in tumor growth in both syngeneic tumor models and a genetic colorectal cancer (CRC) model induced by mutation of the Apc gene (Apc min ). Pharmacological inhibition or genetic deletion of OGT induced a robust genomic instability (GIN), leading to cGAS-dependent production of the type I interferon (IFN-I) and IFN-stimulated genes (ISGs). As a result, deletion of Cgas or Sting from Ogt -/- cancer cells restored tumor growth, and this correlated with impaired CD8+ T cell-mediated antitumor immunity. Mechanistically, we found that OGT-dependent cleavage of host cell factor C1 (HCF-1) is required for the avoidance of GIN and IFN-I production in tumors. In summary, our results identify OGT-mediated genomic stability and activate cGAS-STING pathway as an important tumor cell-intrinsic mechanism to repress antitumor immunity.

A phase 1/2 study of BDC-3042, a novel dectin-2 agonistic antibody, in patients with advanced cancers.

TPS2695 Background: Tumor-associated macrophages (TAMs) are a major component of the immune infiltrate in most cancers and play a key role in establishing the immunosuppressive tumor microenvironment (TME) that enables tumor progression. However, TAMs are phenotypically plastic and have the potential to be reprogrammed into immunostimulatory cells that enhance innate and adaptive anti-tumor immunity. BDC-3042 is a novel agonistic antibody targeting an immune-activating receptor expressed on TAMs known as Dectin-2 ( CLEC6A) [1]. Dectin-2 is a C-type lectin receptor best known for its role in pathogen recognition and induction of protective immune responses against fungi and other microbes. We have previously demonstrated that Dectin-2 agonism stimulates pro-inflammatory cytokine secretion and antigen presentation by TAMs, resulting in robust CD8+ T cell-mediated anti-tumor immunity in syngeneic mouse models [2]. Elevated gene expression of Dectin-2 has been found in a wide range of solid tumor types compared to non-malignant tissues. Nonclinical studies with BDC-3042 have demonstrated its potential to reprogram TAMs and elicit anti-tumor activity as a novel immunotherapeutic approach for diverse human cancers [2]. A phase 1/2, first-in-human, dose-escalation and dose-expansion study of BDC-3042 as a single agent and in combination with a cemiplimab in subjects with advanced cancers has been initiated. Methods: This study is enrolling up to 185 patients with advanced cancers, including non-small cell lung cancer, melanoma, triple-negative breast cancer, renal cell carcinoma, colon cancer, head and neck cancer, and ovarian cancer. Primary objectives of the dose-escalation phase are to define safety and tolerability and to determine the recommended phase 2 dose (RP2D) of BDC-3042 as a monotherapy (Part 1) and in combination with cemiplimab (Part 2). The dose-expansion phase will evaluate preliminary anti-tumor activity of BDC-3042 monotherapy (Part 3) and with cemiplimab (Part 4). Secondary objectives will evaluate pharmacokinetic parameters and pharmacodynamic biomarkers in tumor tissue and in peripheral blood associated with drug exposure. Exploratory analyses will also be conducted to assess BDC-3042’s ability to reprogram TAMs and identify biomarkers associated with BDC-3042 biological activity and with cemiplimab. This study is being conducted in the US and is currently recruiting patients. 1. Kenkel J, et al. Cancer Res. 2023. 2. Kenkel J, et al. J Immunother Cancer. 2021. Clinical trial information: NCT06052852 .

Ganoderma lucidum Polysaccharide Supplementation Significantly Activates T-Cell-Mediated Antitumor Immunity and Enhances Anti-PD-1 Immunotherapy Efficacy in Colorectal Cancer.

Ganoderma lucidum polysaccharide (GLP) is a prebiotic with immunomodulatory effects. However, the therapeutic potential of GLP in tumor immunotherapy has not been fully explored, especially in T cell-mediated antitumor immunity. In this study, we found that GLP significantly inhibited tumor growth and activated antitumor immunity in colorectal cancer (CRC). In the spleens and tumor tissues, the proportion of cytotoxic CD8+T cells and Th1 helper cells increased, while immunosuppressive Tregs decreased. Additionally, microbiota dysbiosis was alleviated by GLP, and short-chain fatty acid production was increased. Meanwhile, GLP decreased the ratio of kynurenine and tryptophan (Kyn/Trp) in the serum, which contributed to antitumor immunity of T cells. More importantly, the combination of GLP and the immune checkpoint inhibitor anti-PD-1 monoclonal antibody further enhanced the efficacy of anti-PD-1 immunotherapy. Thus, GLP as a prebiotic has the potential to be used in tumor immunotherapy.

TIM-3 Expression on Dendritic Cells in Colorectal Cancer.

TIM-3 was originally identified as a negative regulator of helper T cells and is expressed on dendritic cells (DCs). Since the inhibition of TIM-3 on DCs has been suggested to enhance T cell-mediated anti-tumor immunity, we examined its expression on DCs within the tumor microenvironment (TME) in colorectal cancer (CRC) using transcriptomic data from a public database (n = 592) and immunohistochemical evaluations from our cohorts of CRC (n = 115). The expression of TIM-3 on DCs in vitro was examined by flow cytometry, while the expression of its related molecules, cGAS and STING, on immature and mature DCs was assessed by Western blotting. The expression of HAVCR2 (TIM-3) was strongly associated with the infiltration of DCs within the TME of CRC. Immunohistochemical staining of clinical tissue samples revealed that tumor-infiltrating DCs expressed TIM-3; however, their number at the tumor-invasive front significantly decreased with stage progression. TIM-3 expression was higher on immature DCs than on mature DCs from several different donors (n = 6). Western blot analyses showed that the expression of STING was higher on mature DCs than on immature DCs, which was opposite to that of TIM-3. We demonstrated that TIM-3 was highly expressed on tumor-infiltrating DCs of CRC and that its expression was higher on immature DCs than on mature DCs.

EGC enhances tumor antigen presentation and CD8+ T cell-mediated antitumor immunity via targeting oncoprotein SND1

The Staphylococcal nuclease and Tudor domain containing 1 (SND1) has been identified as an oncoprotein. Our previous study demonstrated that SND1 impedes the major histocompatibility complex class I (MHC-I) assembly by hijacking the nascent heavy chain of MHC-I to endoplasmic reticulum-associated degradation. Herein, we aimed to identify inhibitors to block SND1-MHC-I binding, to facilitate the MHC-I presentation and tumor immunotherapy. Our findings validated the importance of the K490-containing sites in SND1-MHC-I complex. Through structure-based virtual screening and docking analysis, (−)-Epigallocatechin (EGC) exhibited the highest docking score to prevent the binding of MHC-I to SND1 by altering the spatial conformation of SND1. Additionally, EGC treatment resulted in increased expression levels of membrane-presented MHC-I in tumor cells. The C57BL/6J murine orthotopic melanoma model validated that EGC increases infiltration and activity of CD8+ T cells in both the tumor and spleen. Furthermore, the combination of EGC with programmed death-1 (PD-1) antibody demonstrated a superior antitumor effect. In summary, we identified EGC as a novel inhibitor of SND1-MHC-I interaction, prompting MHC-I presentation to improve CD8+ T cell response within the tumor microenvironment. This discovery presents a promising immunotherapeutic candidate for tumors.

Abstract PO2-25-02: The microbial metabolite trimethylamine N-oxide promotes antitumor immunity in triple-negative breast cancer

Abstract Immunotherapy has achieved limited success in patients with triple-negative breast cancer (TNBC), an aggressive disease with a poor prognosis. Commensal microbiota have been proven to colonize the mammary gland, but whether and how they modulate the tumor microenvironment remains elusive. We performed a multiomics analysis of a cohort of patients with TNBC (n = 360) and found genera under Clostridiales, and the related metabolite trimethylamine N-oxide (TMAO) was more abundant in tumors with an activated immune microenvironment. Patients with higher plasma TMAO achieved better responses to immunotherapy. Mechanistically, TMAO induced pyroptosis in tumor cells by activating the endoplasmic reticulum stress kinase PERK and thus enhanced CD8+ T cell-mediated antitumor immunity in TNBC in vivo. Collectively, our findings offer new insights into microbiota-metabolite-immune crosstalk and indicate that microbial metabolites, such as TMAO or its precursor choline, may represent a novel therapeutic strategy to promote the efficacy of immunotherapy in TNBC. Citation Format: Hai Wang. The microbial metabolite trimethylamine N-oxide promotes antitumor immunity in triple-negative breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-25-02.

Dose escalation study of a personalized peptide-based neoantigen vaccine (EVX-01) in patients with metastatic melanoma

BackgroundNeoantigens can serve as targets for T cell-mediated antitumor immunity via personalized neopeptide vaccines. Interim data from our clinical study NCT03715985 showed that the personalized peptide-based neoantigen vaccine EVX-01, formulated...

YTHDF2 promotes tumor immune evasion by inhibiting CD8+ T cell-mediated anti-tumor immunity

YTHDF2 promotes tumor immune evasion by inhibiting CD8+ T cell-mediated anti-tumor immunity

Mechanisms of TREM2 mediated immunosuppression and regulation of cancer progression.

Cancer immunotherapy has recently emerged as a key strategy for cancer treatment. TREM2, a key target for regulating the tumor immune microenvironment, is important in cancer treatment and progression. TREM2 is an immune signaling hub that regulates multiple pathological pathways. It not only suppresses anti-tumor immune responses by inhibiting T cell-mediated immune responses, but it also influences tumorigenesis by affecting NK cell-mediated anti-tumor immunity. Noticeably, TREM2 expression levels also vary significantly among different tumor cells, and it can regulate tumor progression by modulating various signaling pathways. Above all, by summarizing the role of TREM2 in cancer immunotherapy and the mechanism by which TREM2 regulates tumor progression, this paper clarifies TREM2's role in both tumor progression and cancer therapy, identifying a new therapeutic target for oncology diseases.

D-mannose targets PD-1 to lysosomal degradation and enhances T cell-mediated anti-tumor immunity

High expression of programmed cell death protein 1 (PD-1), a typical immune checkpoint, results in dysfunction of T cells in tumor microenvironment. Antibodies and inhibitors against PD-1 or its ligand (PD-L1) have been widely used in various malignant tumors. However, the mechanisms by which PD-1 is regulated are not fully understood. Here, we report a mechanism of PD-1 degradation triggered by d-mannose and the universality of this mechanism in anti-tumor immunity. We show that d-mannose inactivates GSK3β via promoting phosphorylation of GSK3β at Ser9, thereby leading to TFE3 translocation to nucleus and subsequent PD-1 proteolysis induced by enhanced lysosome biogenesis. Notably, combination of d-mannose and PD-1 blockade exhibits remarkable tumor growth suppression attributed to elevated cytotoxicity activity of T cells in vivo. Furthermore, d-mannose treatment dramatically improves the therapeutic efficacy of MEK inhibitor (MEKi) trametinib in vivo. Our findings unveil a universally unrecognized anti-tumor mechanism of d-mannose by destabilizing PD-1 and provide strategies to enhance the efficacy of both immune checkpoint blockade (ICB) and MEKi -based therapies.

DLD is a potential therapeutic target for COVID-19 infection in diffuse large B-cell lymphoma patients

Since the discovery of copper induces cell death(cuprotosis) in 2022, it has been one of the biggest research hotspots. cuprotosis related genes (CRGs) has been demonstrated to be a potential therapeutic target for cancer, however, the molecular mechanism of CRGs in coronavirus disease 2019 (COVID-19) infected in DLBCL patients has not been reported yet. Therefore, our research objective is first to elucidate the mechanism and role of CRGs in COVID-19. Secondly, we conducted univariate and multivariate analysis and machine learning to screen for CRGs with common expression differences in COVID-19 and DLBCL. Finally, the functional role and immune mechanism of genes in DLBCL were confirmed through cell experiments and immune analysis. The research results show that CRGs play an important role in the occurrence and development of COVID-19. Univariate analysis and machine learning confirm that dihydrolipoamide dehydrogenase (DLD) is the common key gene of COVID-19 and DLBCL. Inhibiting the expression of DLD can significantly inhibit the cycle progression and promote cell apoptosis of DLBCL cells and can target positive regulation of Lysine-specific demethylase 1 (LSD1, also known as KDM1A) to inhibit the proliferation of DLBCL cells and promote cell apoptosis. The immune analysis results show that high-expression of DLD may reduce T cell-mediated anti-tumor immunity by regulating immune infiltration of CD8 + T cells and positively regulating immune checkpoints LAG3 and CD276. Reducing the expression of DLD can effectively enhance T cell-mediated anti-tumor immunity, thereby clearing cancer cells and preventing cancer growth. In conclusion, DLD may be a potential therapeutic target for COVID-19 infection in DLBCL patients. Our research provides a theoretical basis for improving the clinical treatment of COVID-19 infection in DLBCL.

Enhancement of antitumor response of staphylococcal enterotoxin C2 mutant 2M-118 by promoting cell-mediated antitumor immunity

BackgroundStaphylococcal enterotoxin C2 (SEC2) is used as an immunotherapeutic drug in China. However, SEC2 are limited due to its immunosuppressive and toxic effects. A SEC2 2M-118 (H118A/T20L/G22E) mutant generated by site-directed mutagenesis was studied to elucidate the underlying antitumor mechanism. MethodsThe effects of 2M-118 on mouse fibrosarcoma (Meth-A) cells and cytokine responses were tested in vitro using a transwell assay and ELISA, respectively. 2M-118 effect on immune function in tumor-bearing mice was tested. Cytokine levels and antitumor responses were measured using ELISA and flow cytometry, respectively. TUNEL staining and immunohistochemistry were employed to detect the tumor apoptosis and CD4+ and CD8+ tumor infiltrating lymphocytes (TILs) in tumor tissue. Results2M-118 demonstrated the growth inhibition on tumor cells, increase of cytokines production (IL-2, IFN-γ, and TNF-α) and splenocyte proliferation in vitro. 2M-118 effectively inhibited tumor development and increased lymphocytes and cytokines in a tumor-bearing mouse model. Additionally, 2M-118 regulated the tumormicroenvironment by reducing the number of myeloid-derived suppressor cells (MDSCs), increasing the number of TILs, and inducing tumorcell apoptosis. Conclusion2M-118 promotes immune function and enhances antitumor response. This indicates that 2M-118 could potentially be developed as a novel anti-tumor drug with-highefficiencyandlowtoxicity.

Abstract 5307: Preclinical evaluation of a potential FIC 4-1BB/CD24 bispecific antibody IBD0333

Abstract Background: This study demonstrates the preclinical evaluation of a novel 4-1BB/CD24 bispecific antibody IBD0333. 4-1BB’s activation triggers a signaling cascade that activates both innate and adaptive immune systems. Due to the hepatotoxicity of current anti-4-1BB monoclonal antibodies, tumor-associated antigens (TAA) targeting to specifically activate immune cells in the tumor microenvironment (TME) is expected to enhance its safety profile. CD24 is highly expressed in many cancers, such as ovarian and breast cancer and its high expression is often related to poor prognosis. The signaling pathway of CD24/Siglec-10 triggers a “don’t eat me” signal that facilitates immune escape of tumor cells. Therefore, IBD0333 was designed to target CD24 overexpressed tumor cells and activate CD8+ T cells to induce T cell mediated antitumor immunity in TME of the targeted tumor tissue. To further reduce the toxicity risk, the anti-4-1BB moiety is designed to activate the signaling pathway only when IBD0333 binds to the tumor cells that overexpress CD24. Methods: For CD24 terminus, we applied virus like particle (VLP) as antigen for immunization to obtain functional CD24 antibodies. For 4-1BB terminus, competitive ELISA/FACS analysis as well as amino acid point mutation binding ability analysis based on the receptor crystal structure were performed to characterize the binding epitope. The in vivo mice efficacy and toxicity study, as well as cynomolgus monkey toxicity study were also conducted to describe the anti-tumor activity and safety profile. For IBD0333, we verified binding affinity by FACS to cancer cells and the 4-1BB activity in reporter-gene assay. IL2 and INF-γ secretion assay were performed to evaluate the PBMC activation. C57BL/6J-h4-1BB humanized mice bearing MC38-hCD24 colon cancer cells were used to validate the anti-tumor efficacy of IBD0333. Preclinical PK and toxicity study was also performed in cynomolgus monkeys to describe the safety profile of IBD0333. Results: IBD0333 showed excellent binding and PBMC stimulation activities. In toxicology studies of IBD0333, no obvious abnormality in mice or cynomolgus monkeys administered with IBD0333 was observed. The MTD was estimated to be greater than 200 mg/kg with no severe side effects observed in the study, showing that IBD0333 has great potential to achieve significantly improved safety profile. As to efficacy, IBD0333 showed excellent tumor inhibition activities in mice model with 99% tumor growth inhibition at 1 mg/kg and 100% at 3 mg/kg. Conclusion: IBD0333 is a clinical stage, potential first-in-class, 4-1BB/CD24 bsAb that simultaneously stimulates both innate and adaptive immunity to achieve strong synergistic effects with reduced hepatotoxicity. The IND approvals from the FDA and the NMPA have been obtained and the Phase I clinical trial of IBD0333 in locally advanced/metastatic solid tumors or non-Hodgkin’s lymphoma is currently on-going. Citation Format: Xiaoling Jiang, Chongbing Wu, Zi Chen, Liusong Yin. Preclinical evaluation of a potential FIC 4-1BB/CD24 bispecific antibody IBD0333 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5307.

Abstract 1393: Tumor-infiltrating monocyte-like cells create metastasis-promoting immunosuppressive microenvironment via THBS1 production in aggressive colorectal cancer

Abstract Mesenchymal subtype of colorectal cancer (CRC) is characterized by high metastatic potential, poor prognosis and an immunosuppressive tumor microenvironment (TME). Although tumor-infiltrating myeloid cells constitute the primary population of immune components in the TME, targeting myeloid cells remains highly challenging owing to the developmental and functional heterogeneity of their subsets. Thus, a deeper understanding of how tumor-infiltrating myeloid cells contribute to the creation of a tumor-promoting TME is needed to identify rational strategies against CRCs with aggressive phenotypes. Recent studies have revealed that multiple inflammatory signatures are elevated in mesenchymal CRCs, suggesting a strong association between inflammation and stromal activation. In this study, we focus on thrombospondin-1 (THBS1), which is a matricellular protein, typically expressed in inflammatory processes. Immunostaining and RNA in situ hybridization on human CRC samples revealed a clear localization of THBS1 expression in tumor stroma. Analyses of the cancer genome atlas (TCGA) and tissue microarray of human CRCs show a positive correlation between increased expression of THBS1 and the mesenchymal phenotype, immunosuppression, and poor prognosis in human CRCs. Utilizing immunocompetent orthotopic implantation systems with aggressive mouse tumor organoids (MTO) on wild-type and Thbs1 knockout (Thbs1−/−) mice, we demonstrated that loss of THBS1 in the TME suppressed metastatic formation accompanied by an increased infiltration of tumor-infiltrating CD8+ T cells. Depletion of CD8+ T cells by neutralizing antibody restored metastases in MTO-bearing Thbs1−/− mice, indicating that THBS1 promotes metastatic formation by suppressing CD8+ T cell-mediated anti-tumor immunity. Analyses of single cell RNA sequencing data of human CRCs and orthotopic MTO tumors revealed that bone marrow (BM)-derived monocyte-like cells are the primary source of THBS1. This notion was further supported by analyzing the orthotopic MTO tumors in chimeric mice generated by bone marrow transplantation. Finally, we identified stroma-derived CXCL12 as a key chemokine for the recruitment of THBS1-producing monocyte-like cells by analyzing orthotopic MTO tumors treated with CXCL12 inhibitor. Our study contributes to a better understanding of the processes underlying THBS1 production by monocyte-like cells that mediates immune evasion that confer aggressive features to CRCs. These findings provide insights for the treatment of this poor-prognosis malignancy. Citation Format: Mayuki Omatsu, Yuki Nakanishi, Kosuke Iwane, Naoki Aoyama, Takahisa Maruno, Hiroaki Kasashima, Masakazu Yashiro, Akihisa Fukuda, Hiroshi Seno. Tumor-infiltrating monocyte-like cells create metastasis-promoting immunosuppressive microenvironment via THBS1 production in aggressive colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1393.

Abstract 1358: Elucidating the contribution of T cell-intrinsic VISTA to the suppression of antitumor T cell immunity

Abstract Immune checkpoint receptors (ICRs) negatively regulate antitumor immune responses. While significant advances have been made in understanding the mechanisms of well-established ICRs such as PD-1 and CTLA-4, other checkpoint proteins remain incompletely characterized and may be targeted to synergistically boost antitumor immunity. One such protein is V-domain immunoglobulin suppressor of T-cell activation (VISTA), an ICR whose expression curtails the function of several lymphoid and myeloid lineages, including tumor-reactive cytotoxic T cells. Globally blocking VISTA elicits potent T cell-mediated antitumor immunity and systemic myeloid cell-mediated inflammatory responses. Mechanistically, VISTA has been shown to inhibit T cell activation by acting as an inhibitory ligand on antigen-presenting cells. However, the impact of T cell-intrinsic VISTA on modulating tumor-reactive T cell responses has not been thoroughly investigated, and it remains unclear whether blocking T cell-specific VISTA is adequate for revitalizing T cell-mediated tumor control. In this study, we utilized VISTA conditional knockout mice models to examine the relative contribution of T cell-intrinsic VISTA versus myeloid-derived VISTA in the regulation of antitumor immunity. We present evidence that blocking VISTA on T cells alone is insufficient to induce strong antitumor immune responses, whereas blocking VISTA on myeloid cells counteracts its dominant role in orchestrating T cell suppression. Citation Format: Sachin Patnaik, Elizabeth Delaney, Cassandra Gilmour, Keman Zhang, Amin Zakeri, Hieu M. Ta, Prerana B. Parthasarathy, Tyler Alban, Timothy Chan, Li Lily Wang. Elucidating the contribution of T cell-intrinsic VISTA to the suppression of antitumor T cell immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1358.

Fatostatin promotes anti-tumor immunity by reducing SREBP2 mediated cholesterol metabolism in tumor-infiltrating T lymphocytes

Aberrant lipid metabolism impacts intratumoral T cell-mediated immune response and tumor growth. Fatostatin functions as an inhibitor of sterol regulatory element binding protein (SREBP) activation. However, the complex effects of fatostatin on cholesterol metabolism in the tumor microenvironment (TME) and its influence on T cell anti-tumor immunity remain unclear. In this study, fatostatin effectively suppressed B16 melanoma, MC38 colon cancer, and Lewis lung cancer (LLC) transplanted tumor growth in immunocompetent mice by reducing SREBPs-mediated lipid metabolism, especially cholesterol levels. Mechanistically, fatostatin decreased intracellular cholesterol accumulation and inhibited X-box binding protein 1 (XBP1)-mediated endoplasmic reticulum (ER) stress, reducing Treg cells and alleviating CD8+ T cell exhaustion in the TME, exerting anti-tumor activity. Nevertheless， this effect was impaired in immunodeficient nude mice, suggesting fatostatin's anti-tumor efficacy in transplanted tumors partly relies on T cell-mediated anti-tumor immunity. Our study highlights SREBP2-mediated cholesterol metabolism as a potential strategy for anti-tumor immunotherapy, and confirms fatostatin's promise in tumor immunotherapy.

Abstract 5629: MEF2D regulates T cell function via the CD70-CD27 signaling axis and promotes immune escape in hepatocellular carcinomas

Abstract Background: Immune escape remains a challenge in the treatment of hepatocellular carcinoma (HCC), one of the most common and deadly cancers in the world. The transcription factor, myocyte enhancer factor 2D (MEF2D), is important in the regulation of differentiation and adaptive responses in many cancers, such that we tested its role in HCC. Methods: We knocked down MEF2D in HCC cell lines and analyzed HCC tissues and cell lines by RNA sequencing, Western blot and immunohistochemistry. MEF2D protein acetylation and proteins that interact with MEF2D were identified by coimmunoprecipitation assay. Chromatin immunoprecipitation was used to analyze the regulation of CD70 transcription by MEF2D. H22 cells, with MEF2D knockout or without (controls), were injected into the livers of syngeneic BALB/c mice. Flow cytometry was used to analyze the function of T cells in tumors, spleens, and lymph nodes. Results: Through database searches, we noted that MEF2D and CD70 were upregulated in HCC and associated with shorter patient survival times. Compared to WT tumors, injection of MEF2D-knockdown HCC cells into immunocompetent mice led to smaller tumors with increased T cell infiltration, activation, and impaired T-regulatory (Treg) cell suppressive function. Mechanistically, we found that MEF2D binds to the promoter region of CD70 gene and activates its transcription. Moreover, acetylation of MEF2D enhances the binding of MEF2D to the CD70 promoter and further promotes its transcription. CD70 blocking antibody inhibited activation of the CD70-CD27 signaling axis in murine HCC tumors, leading to impaired immunosuppressive function of Tregs and enhanced T cell-mediated anti-tumor immune responses. Thus, regulation of the CD70-CD27 signaling axis by MEF2D affects the numbers and functions of Treg cells and thereby controls T cell infiltration. Conclusions: MEF2D in HCC cells increases the expression of CD70 and blocks T cell-mediated anti-tumor immunity via the CD70-CD27 signaling axis. Strategies to manipulate this pathway might increase the efficacy of immune therapies for HCC. Citation Format: Fanhua Kong, Liqing Wang, Qifa Ye, Yan Xiong, Wayne W. Hancock. MEF2D regulates T cell function via the CD70-CD27 signaling axis and promotes immune escape in hepatocellular carcinomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5629.

Abstract 3595: A retrospective analysis of the clinical characteristics of metastastic solid cancer patients with cytokine-induced killer cells combined immune checkpoint inhibitor immunotherapy

Abstract Background: Cytokine-induced killer cells (CIKs), obtained through ex vivo expasion from peripheral blood mononuclear cells, are phenotypically and functionally shared with both T and NK cells. Within the T cell group, it can be classified into a group that simultaneously expresses CD3 and CD56 molecules (range: 30% to 70%) and a group representing CD3+ CD56- phenotype (range: 20% to 60%). It also contains a small population (< 30%) of CD3 CD56+ NK cells. They can exhibit potent MHC-unrestricted cytotoxicity for both hematologic and solid tumors, but they are not harmful in hematopoietic precursors and normal tissues. Anti-programmed death-1 (PD-1) antibodies reinvigorate T cell-mediated antitumor immunity. PD-1 blockade antibody might significantly increase the cytotoxic potency of CIK cells via increasing proliferative capacity and IFN-r secretion. This retrospective study is the first to combine CIK cells with PD-1/PD-L1/CTLA-4 blockade(Immune checkpoint inhibitors, ICIs) in patients with metastatic solid cancers. Methods: We analyzed 225 heavily treated metastastic solid cancer patients receiving CIK cell (Immunecell-LC, GC cell inc provide.) and with ICIs. Blood Sampling for CIK cells production was performed after 3 days after ICIs administration. Patients received a single intravenous infusion of activated autologous CIK cells every 2 weeks. ICIs was administered according to the protocol of each drug regardless of the CIK cells administration date. The primary end points were safety and adverse event (AE) profiles. Objective responses, overall survival (OS), progression-free survival (PFS), and diseae control rate were secondary end points. Results: Treatment-related AEs occurred in 154/225 patients. Grade 3 or 4 toxicities, including fever and chills, were observed in 28 patients. All treatment-related AEs were tolerable and no death due to autoimmune disease. When administration ICIs, CIK cells exhibited excellent antitumor properties and increased IFN-γ secretion. Objective responses (complete or partial responses) were observed in 67 of the 225 patients. One patients with hepatocellular carcionma had complete response. In most patients who showed an objective response, the effectiveness was maintained for more than 6 months. The overall disease control rate in the patients was 58.9%. At the time of this report, the median OS and PFS were 18.6 and 7.1 months in hepatocellular carcinoma patients and were 13.1 and 6.5 months in triple negative breast cancer patients, respectively. Conclusion: Treatment with activated autologous CIK cells and ICIs was safe and exerted encouraging antitumor activity in metastastic solid cancers. Phase 2 clinical studies for each tumor type will be conducted. Keywords: Cytokine-induced killer cells, Immune check inhibitors, Safety, Objective response Citation Format: Jonggwon Choi, Jong Yeup Kim, Dong Won Yang, Gun He Nam. A retrospective analysis of the clinical characteristics of metastastic solid cancer patients with cytokine-induced killer cells combined immune checkpoint inhibitor immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3595.

Abstract 6531: Anti-tumor immune function of NR2F6, an orphan nuclear receptor, in stromal cells

Abstract Growing evidence points to the importance of the tumor microenvironment (TME) in tumor growth control, progression, and therapy response. Among those is the greater understanding of immune system components within the TME as mediators of tumor growth control. NR2F6 is an orphan nuclear receptor, which was shown to serve as an immune intrinsic checkpoint component and has been suggested to elicit tumor-intrinsic suppression of anti-tumor immunity. Correspondingly, genetic depletion of NR2F6 in CD8 T cells abrogates the immune-activating cytokines (e.g., IL-2, IFNg). In addition, genetic ablation of NR2F6 in melanoma cells activates CD8 T cell-mediated anti-tumor immunity partly by suppressing the expression of tumor-intrinsic immune repressors NACC1 and FKBP10. Notably, combined genetic ablation of tumor cells (NR2F6 KO melanoma) and stroma cells (NR2F6 KO mouse) resulted in a more pronounced inhibition of tumor growth compared with ablation of either tumor cells or TME. The latter provides the foundation for screening NR2F6 inhibitors, which are expected to have a strong systemic (tumor inhibition and immune cell activation) effect on tumor growth. Interestingly, single-cell transcriptomic data from human tumors identified high expression of NR2F6 in stroma cells, cancer-associated fibroblasts (CAFs), and tumor-associated endothelial cells (TAEs). Consistent with these, scRNAseq analysis of mouse melanoma revealed higher expression of NR2F6 in SMA+ immune suppressive myo-CAFs than in immune activating CAFs. Studies that directly reveal the role of stromal NR2F6 in anti-tumor immunity and tumor growth and the state of NR2F6 inhibitors will be discussed. Citation Format: Hyungsoo Kim, Yongmei Feng, Marria Radaeva, Eduard Sergienko, Artem Cherkasov, Ze'ev A. Ronai. Anti-tumor immune function of NR2F6, an orphan nuclear receptor, in stromal cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6531.

HSP90 inhibition suppresses tumor glycolytic flux to potentiate the therapeutic efficacy of radiotherapy for head and neck cancer.

Glycolytic metabolism may account for antitumor immunity failure. Pyruvate kinase M2 (PKM2) and platelet phosphofructokinase (PFKP), two key enzymes involved in the glycolytic pathway, are hyperactivated in head and neck squamous cell carcinoma (HNSCC). Using ganetespib as a drug model for heat shock protein 90 (HSP90) inhibition and combining results from clinical trials and animal treatment, we demonstrated that HSP90 inhibition leads to a blockade of glycolytic flux in HNSCC cells by simultaneously suppressing PKM2 and PFKP at both the transcriptional and posttranslational levels. Down-regulation of tumor glycolysis facilitates tumor infiltration of cytotoxic T cells via suppression of glycolysis-dependent interleukin-8 signaling. The addition of ganetespib to radiation attenuates radiation-induced up-regulation of PKM2 and PFKP and potentiates T cell-mediated antitumor immunity, resulting in a more potent antitumor effect than either treatment alone, providing a molecular basis for exploring the combination of HSP90 inhibitors with radiotherapy to improve outcomes for patients with HNSCC.