Mouse T-cell Research Articles

A single-dose intranasal live-attenuated codon deoptimized vaccine provides broad protection against SARS-CoV-2 and its variants

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) continues its significant health and economic impact globally. Despite the success of spike-protein vaccines in preventing severe disease, long-lasting protection against emerging variants and the prevention of breakthrough infections and transmission remain elusive. We generate an intranasal live-attenuated SARS-CoV-2 vaccine, CDO-7N-1, using codon deoptimization. CDO-7N-1 shows highly attenuated replication and minimal or no lung pathology in vivo over multiple passages. It induces robust mucosal and systemic neutralizing antibody and T-cell subset responses, in mice (female K18-hACE2 and male HFH4-hACE2 mice), hamsters, and macaques triggered by a single immunization. Mice and hamsters vaccinated with CDO-7N-1 are protected from challenge with wild-type (WT) SARS-CoV-2 and other variants of concern. Serum from vaccinated animals neutralizes WT SARS-CoV-2, variants of concern (beta and delta), variants of interest (omicron XBB.1.5) and SARS-CoV-1. Antibody responses are sustained and enhanced by repeated immunization or infection with WT SARS-CoV-2. Immunity against all SARS-CoV-2 proteins by CDO-7N-1 should improve efficacy against future SARS-CoV-2 variants.

Advancing vaccine development: Evaluation of a mannose-modified lipid nanoparticle-based candidate for African swine fever p30 mRNA vaccine eliciting robust immune response in mice

The African swine fever virus (ASFV) continues to pose significant economic and pandemic risks. Consequently, discovering new, efficient vaccines is crucial. Messenger RNA (mRNA) vaccines have emerged as promising candidates, providing minimal risk of insertional mutagenesis, high safety profiles, effectiveness, rapid scalability in production, and cost-effectiveness. In this study, we have developed an ASF p30 mRNA vaccine candidate (mRNA/Man-LNP) employing mannose-modified lipid nanoparticles (LNPs). The mRNA/Man-LNP exhibited effective antigen presentation and facilitated dendritic cells (DCs) maturation. Notably, it elicited strong IgG titers and activated CD4+ and CD8+ T-cells in immunized mice, all while adhering to stringent biosafety standards. This investigation demonstrates that mRNA/Man-LNP can trigger both humoral and cellular immune responses, suggesting its potential as a potent and promising vaccine candidate for controlling African swine fever (ASF).

Abstract B006: GSTT2 modulates immune activation and impacts response to BCG immunotherapy in bladder cancer

Abstract Whilst M. bovis Bacillus Calmette-Guérin (BCG) therapy is the gold-standard for treating high risk non-muscle invasive bladder cancer (NMIBC), 30-40% of patients fail therapy, resulting in disease recurrence and progression. Loss of glutathione-S-transferase theta 2 (GSTT2) expression resulting from a promoter deletion, has been associated with modulation of intracellular ROS and BCG survival in BC cells. Retrospective analysis of NMIBC patients revealed that patients with the promoter deletion responded better to fewer instillations of BCG. To understand these responses, wildtype (WT) and GSTT2-knockout (KO) mice were implanted with MB49-PSA BC cells, either subcutaneously or orthotopically, and treated with weekly BCG instillations. Subcutaneous tumors were harvested after 3 BCG instillations for flow cytometry analysis, or after 4 BCG instillations for immunofluorescence (IF) imaging and gene expression analysis. Bladders (orthotopic model) were harvested after 4 BCG instillations for single-cell RNA sequencing. Splenocytes from WT and KO male mice were also stimulated in-vitro with TLR agonists, for 48h, to assess immune responses. In the subcutaneous model, in male mice, the cure rate was higher in WT mice (57%) compared to KO mice (0%). Flow cytometry analysis showed significantly higher numbers of tumor-associated CD8+ T-cells in BCG-treated KO males compared to WT males; however, IF imaging revealed higher penetration of CD8+ T-cells in tumors from WT males. In female mice, the cure rate was similar in WT (25%) and GSTT2-KO (38%) mice. IF imaging showed higher penetration of CD8+ T-cells in KO females. Quantitative real-time PCR (q-PCR) analysis of BCG-treated subcutaneous tumors from female mice revealed lower expression of the immune exhaustion markers, PD-L1 and CTLA-4, in KO mice compared to WT mice. Similarly, in the orthotopic model (female mice), q-PCR analysis of bladders also showed lower expression of PD-L1 and CTLA-4 in KO mice compared to WT mice. Single-cell RNA sequencing of bladders from BCG-treated mice revealed differences in the expression of genes such as Peak1, Hmga2, Scl2a1, Kras, Ahank, Gsta4, Mecom and Sh3gl2, of which Gsta4, Mecom, Sh3gl2, Hmga2 and Peak1 were validated using q-PCR. In-vitro analysis of splenocytes from male mice revealed higher levels of IL-6, IL-1β and IFN-α, after stimulation with TLR7/8 and TLR9 agonists, in KO splenocytes relative to WT splenocytes. Despite the higher levels of cytokine production by splenocytes and higher proportion of tumor-associated CD8+ T-cells in KO male mice, these mice fared poorly, which could be explained by immune exhaustion or lack of immune penetration into the tumor. In females, lower expression of immune exhaustion markers in KO mice did not yield better responses; however, single-cell data showed differences in expression of genes associated with pro- and anti-tumorigenic pathways, which could influence response. Thus, loss of GSTT2 may influence the response to BCG therapy, through modulating downstream signaling pathways and immune responses. Citation Format: Mugdha Vijay Patwardhan, Kane Toh, Edmund Chiong, Ratha Mahendran. GSTT2 modulates immune activation and impacts response to BCG immunotherapy in bladder cancer [abstract]. In: Proceedings of the AACR Special Conference on Bladder Cancer: Transforming the Field; 2024 May 17-20; Charlotte, NC. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(10_Suppl):Abstract nr B006.

Abstract 6593: Rejuvenation of tumor-infiltrating lymphocytes (TIL): A novel strategy to revitalize TIL antitumor function for cell therapy

Abstract TIL therapy is a promising approach for the treatment of metastatic solid tumors, but its efficacy is limited by T-cell exhaustion and terminal differentiation. In addition, recent studies have underscored the adverse effects of aging on T cells. Reprogramming T cells into induced pluripotent stem cells (iPSC) and differentiating them back to the T-cell lineage has proven to be complex and time-consuming. In particular for TIL applications, de novo T cell production via iPSCs requires each TCR in the final product to be derived from an independently established iPSC clone. To overcome these barriers, we developed a novel technology called Rejuvenation, which bypasses the need for reprogramming of T cells into iPSCs. Rejuvenated TIL products retain their TCR diversity while offering several significant advantages, including reduced T-cell epigenetic age, improved expansion capacity, stem cell-like phenotype, and enhanced secretion of cytokines upon activation by target antigens. In this study, we used TIL derived from patients with melanoma and NSCLC. Rejuvenated TIL were generated by the transient expression of transcription factors in a process called ‘Partial Reprogramming’ and returned back to a T-cell lineage phenotype by a process called ‘Redirection’. Partially reprogrammed TIL showed an altered morphology resembling adherent stromal cells and down-regulated conventional T-cell markers including CD3, CD4, and CD8. Redirected T cells reacquired a conventional CD4/CD8 phenotype including morphology, surface markers and function, and demonstrated decreased epigenetic age (>7 years younger, N=3). We also observed a higher proliferative capacity, improved metabolic state, and increased expression of biomarkers associated with T-cell stemness, including CCR7 and CD62L, when compared with untreated TIL. Rejuvenated TIL demonstrated improved cytokine secretion, including IFNγ, TNFα and IL-2 in functional assays. Immune repertoire analysis revealed a significant polyclonal population of putative tumor-reactive TCRs. In vivo functionality was also evaluated using a xenograft model of engineered A375 melanoma cell line that agonizes T-cells in hIL2-NOG mice. Adoptive transfer of rejuvenated TIL resulted in significantly improved suppression of tumor growth and prolonged survival compared with TIL expanded by conventional methods. These results were also confirmed in other surrogate models, including rejuvenated PBMC, TCR and CAR T cells, demonstrating the broad applicability of Rejuvenation technology. Our results indicate TIL Rejuvenation enhances the functionality and antitumor characteristics of T cells, while preserving a broad TCR repertoire. This technology holds substantial promise and may pave the way for the development of the first rejuvenated autologous polyclonal TIL therapy for treatment of advanced solid tumors. Citation Format: Raul Vizcardo, Yin Huang, Jessica Fioravanti, Takuya Maeda, Naritaka Tamaoki, Yasuhiro Yamazaki, Burak Kutlu, Kriti Bahl, Biao Wang, Zheng Zhong, Shobha Potluri, Nicholas P. Restifo, Gary Lee. Rejuvenation of tumor-infiltrating lymphocytes (TIL): A novel strategy to revitalize TIL antitumor function for cell therapy [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 6593.

Abstract 3969: Alzheimer's disease-associated amyloid precursor protein improves anti-tumor immunity by inhibiting ceramide-mediated lethal mitophagy and restoring mitochondrial fumarate metabolism in aging T-cells

Abstract The association between Alzheimer’s disease (AD) and lower cancer incidence has been observed in several epidemiological studies without much mechanistic insight. We aimed to understand this cancer resistance mechanism linked to AD and exploit it for broader cancer therapies. A hallmark of AD is the accumulation of amyloid precursor protein (APP) in neuronal mitochondria, inhibiting mitophagy, abrogating the clearance of dysfunctional mitochondria, and contributing to AD pathology. In addition to neurons, mitophagy plays an important role in T-cells, where excessive ceramide-dependent mitophagy in aging T-cells inhibits their energy metabolism and limits their anti-tumor functions. Thus, attenuation of ceramide-dependent mitophagy plays a favorable role in enhancing aging T-cell anti-tumor function. Given that APP is also processed in T-cells, we hypothesized that APP accumulates aberrantly in aging Alzheimer’s T-cells, inhibiting mitophagy and enhancing T-cell anti-tumor activity. Employing techniques of lipidomics, metabolomics, imaging, molecular biology, and genetic models, we show that AD T-cells from a mouse model and human patients are protected against aging-associated ceramide-dependent mitophagy, which enhanced their secretion of inflammatory anti-tumor cytokines. The excessive localization of APP to the T-cell mitochondria, where it inhibits the accumulation of ceramide synthase 6 (CerS6) and C14/C16-ceramides, attenuated the levels of mitophagy and protected the Alzheimer’s T-cells from metabolic defects observed in aging, namely protecting against the exhaustion of fumarate pools. Both in vitro and in vivo re-supplementation of fumarate to aging WT mouse T-cells effectively rescued their viability, cytokine production, and tumor killing capacity both in vitro and in adoptive T-cell transfers to mice with melanoma, functionally mimicking the AD phenotype. The fumarate supplementation also led to a decrease in ceramide-dependent mitophagy in the WT aging T-cells, indicating an interplay between ceramide-dependent mitophagy and fumarate metabolism which contributes to the protection of the anti-tumor function in aging AD T-cells. Moreover, we show that Alzheimer’s mice that express APP in the brain and T-cells, but not AD mice that express APP only in the brain, are protected against the growth of both carcinogen-induced and allografted tumors. Finally, transfer of mitochondria from AD T-cells to aging WT T-cells improved their metabolic fitness and anti-cancer functions. In summary, we show that AD-associated APP improves anti-tumor immunity of aging T-cells by inhibiting ceramide-mediated lethal mitophagy and restoring mitochondrial fumarate metabolism. These data provide a novel mechanism to explain reduced cancer incidences in AD patients. Citation Format: Mohamed Faisal Kassir, Han G. Lee, Natalia Oleinik, Wyatt Wofford, Chase Walton, F. Cansu Atilgan, Paramita Chakraborty, Kubra Calisir, Ozgur Sahin, Shikhar Mehrotra, Besim Ogretmen. Alzheimer's disease-associated amyloid precursor protein improves anti-tumor immunity by inhibiting ceramide-mediated lethal mitophagy and restoring mitochondrial fumarate metabolism in aging T-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 3969.

Deletion of MyD88 in T Cells Improves Antitumor Activity in Melanoma

Cytotoxic CD8+ T cells are central to the antitumor immune response by releasing cytotoxic granules that kill tumor cells. They are activated by antigen-presenting cells, which become activated by DAMPs (damage associated molecular patterns) through MyD88. However, the suppressive tumor microenvironment promotes T-cell tolerance to tumor antigens, in part by enhancing the activity of immune checkpoint molecules that prevent CD8+ T-cell activation and cytotoxicity. MyD88 limits CD4+ T-cell activation during cardiac adaptation to stress. A similar mechanism is hypothesized to exist in CD8+ T cells that could be modulated to improve antitumor immunity. Herein, adoptive transfer of MyD88-/- CD8+ T cells in melanoma-bearing T-cell-deficient mice resulted in slower tumor growth, greater intratumoral T-cell accumulation, and higher melanoma cell death compared with transfer of wild-type CD8+ T cells. These findings were also observed in T-cell-specific MyD88-/- mice compared with wild-type littermates implanted with melanoma. Mechanistically, deletion of MyD88 enhanced CD8+ T-cell activation and survival, and T-cell receptor induced degranulation of cytotoxic molecules, overall improving the killing of melanoma cells. This enhanced cytotoxicity was retained in mice bearing tumors expressing the specific antigen for which cytotoxic T-cells were restricted. This study's results demonstrate a conserved mechanism for MyD88 in modulating CD8+ T-cell activation and represent a novel target in improving cancer immunotherapy.

A Dual Role of SOX11 Expression in the Formation of T-Cell Acute Lymphoblastic Leukemia in Mouse Models

Introduction: T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy that accounts for 10%-15% of pediatric and 25% of adult ALL cases. Intensified chemotherapy and bone marrow transplants have improved the survival of T-ALL patients. However, around 20% of patients still suffer from primary resistant or relapsed T-ALL. Therefore, improving our knowledge of T-ALL biology and developing precision oncology therapeutics is essential for further progress in T-ALL treatment. SRY-related HMG-box 11 (SOX11) is a transcription factor that regulates the development and survival of multiple embryonic tissues and is crucial for the nervous system. SOX11 is expressed in a multitude of tumor types, where it has been associated with either increased or decreased cell proliferation, metastatic potential, and with either good or bad prognosis, depending on cancer type. Despite being absent in the T-cell lineage, SOX11 is expressed in a subset of T-ALLs, where it plays an unknown role. Based on having a malignantly restricted expression, we hypothesize that SOX11 might be oncogenic in T-ALL. Aim: Identify the role of aberrant SOX11 expression in (pre)leukemic T-cells. Methods: Using a conditional Rosa26-SOX11 overexpression mouse model, we generated mice with T-cell specific (using Lck-cre) SOX11 expression (SOX11 Lck). To assess the self-renewal potential of SOX11 Lck thymocytes, we performed thymic transplantations on sublethally irradiated mice expressing a different allele of CD45. To study SOX11 in a leukemic context, we crossed the SOX11 Lck mice with two established T-ALL mouse models that are either driven by the overexpression of Lmo2 (SOX11 Lck-Lmo2 CD2) or by the loss of the tumor suppressor Pten (SOX11/Pten Lck). An aging cohort of these T-ALL models was followed, and tumor samples were collected. Thymi of 8-weeks old mice were used to study the impact of SOX11 in a pre-leukemic context, and T-cell tumors arising in these models were also used for RNA-sequencing. Using a retroviral strategy, we overexpressed SOX11 in human cord blood stem cells, which we differentiated towards the T-cell lineage ex vivo by co-culturing them on OP9 stromal cells expressing Delta-like Notch ligand 4. Furthermore, we transduced Jurkat cells with a SOX11 expression vector, or with an empty vector, and injected the cells into immunocompromised mice to assess the effect of SOX11 on tumor growth in vivo. Results: In SOX11 Lck mice, we found a significant increase in the immature double-negative 3 (DN3) thymic fraction, with a concomitant decrease in the amount of more mature double-positive CD4 +CD8 + (DP) thymocytes (Fig. A). A possible explanation for this phenotype would be the establishment of a stem-like self-renewal program similar to the one driven by Lmo2. However, by performing thymic transplantations into sublethally irradiated mice, we concluded that SOX11 does not confer self-renewal properties to thymocytes. Additionally, we aged a cohort of SOX11 Lck mice and did not observe formation of T-cell malignancies up to 500 days of age. Given that the expression of SOX11 does not suffice to produce T-cell tumors, we generated the SOX11 Lck-Lmo2 CD2 and SOX11/Pten Lck T-ALL mouse models. In SOX11 Lck-Lmo2 CD2 mice, we found a synergistic effect of the co-expression of both genes on the expansion of DN3 thymocytes (Fig. A), which led to accelerated leukemia formation (Fig. B). By sequencing the RNA of pre-leukemic and leukemic DN3 cells, we observed that SOX11 is mostly regulating cell adhesion, morphology, and cell-cell interactions to promote this oncogenic phenotype in Lmo2-driven T-ALL. On the other hand, SOX11/Pten Lck mice suffered from delayed leukemogenesis (Fig. B), and this tumor suppressor role might be associated with the decrease in DP cells observed in the pre-leukemic stage. Lastly, we set out to validate these findings in a human context. The ex vivo differentiation of human hematopoietic stem cells toward the T-cell lineage showed that SOX11 strongly accelerates early commitment to double-negative T-cell precursors. Also, we observed that Jurkat T-ALL cells engraft faster in immunocompromised mice when expressing SOX11. Conclusions: By generating multiple models of SOX11 expression in the T-cell lineage, we showed that SOX11 impacts T-cell differentiation, both in mice and humans, and that it can promote or hinder T-ALL formation depending on the oncogenic driver.

Clonality, trafficking, and molecular alterations among Hprt mutant T lymphocytes isolated from control mice versus mice treated with N-ethyl-N-nitrosourea.

Mutations in T lymphocytes (T-cells) are informative quantitative markers for environmental mutagen exposures, but risk extrapolations from rodent models to humans also require an understanding of how T-cell development and proliferation kinetics impact mutagenic outcomes. Rodent studies have shown that patterns in chemical-induced mutations in the hypoxanthine-guanine phosphoribosyltransferase (Hprt) gene of T-cells differ between lymphoid organs. The current work was performed to obtain knowledge of the relationships between maturation events during T-cell development and changes in chemical-induced mutant frequencies over time in differing immune compartments of a mouse model. A novel reverse transcriptase-polymerase chain reaction based method was developed to determine the specific T-cell receptor beta (Tcrb) gene mRNA expressed in mouse T-cell isolates, enabling sequence analysis of the PCR product that then identifies the specific hypervariable CDR3 junctional region of the expressed Tcrb gene for individual isolates. Characterization of spontaneous Hprt mutant isolates from the thymus, spleen, and lymph nodes of control mice for their Tcrb gene expression found evidence of in vivo clonal amplifications of Hprt mutants and their trafficking between tissues in the same animal. Concurrent analyses of Hprt mutations and Tcrb gene rearrangements in different lymphoid tissues of control versus N-ethyl-N-nitrosourea-exposed mice permitted elucidation of the localization and timing of mutational events in T-cells, establishing that mutagenesis occurs primarily in the pre-rearrangement replicative period in pre-thymic/thymic populations. These findings demonstrate that chemical-induced mutagenic burden is determined by the combination of mutagenesis and T-cell clonal expansion, processes with roles in immune function and in the pathogenesis of autoimmune disease and cancer.

Anticancer effect of metformin alone and in combination with 2-deoxy-D-glucose on mouse T cell lymphoma EL4 cells

Metformin is a treatment used widely for non-insulin-dependent diabetes mellitus with few side effects and acts by inhibiting hepatic gluconeogenesis and glucose absorption from the gastrointestinal tract. Lymphoma is one of the most common hematological malignancies in dogs. Chemotherapy is used mainly on lymphoma, but further research on developing anticancer drugs for lymphoma is needed because of its severe side effects. This study examined the anticancer effects of metformin alone and in combination with 2-deoxy-D-glucose (2-DG), a glucose analog, on EL4 cells (mouse T-cell lymphoma). Metformin reduced the metabolic activity of EL4 cells and showed an additive effect when combined with 2-DG. In addition, cell death was confirmed using a trypan blue exclusion test, Hochest 33342/propidium iodide (PI) staining, and Annexin V/PI staining. An analysis of the cell cycle and mitochondria membrane potential (MMP) to investigate the mechanism of action showed that metformin stopped the G2/M phase of EL4 cells, and metformin + 2-DG decreased MMP. Metformin exhibited anticancer effects as a G2/M phase arrest mechanism in EL4 cells and showed additive effects when combined with 2-DG via MMP reduction. Unlike cytotoxic chemotherapeutic anticancer drugs, metformin and 2-DG are related to cellular glucose metabolism and have little toxicity. Therefore, metformin and 2-DG can be an alternative to reduce the toxicity caused by chemotherapeutic anticancer drugs. Nevertheless, research is needed to verify the in vivo efficacy of metformin and 2-DG before they can be used in lymphoma treatments.

Correlative CD4 and CD8 T-cell immunodominance in humans and mice: Implications for preclinical testing

Antigen-specific T-cell recognition is restricted by Major Histocompatibility Complex (MHC) molecules, and differences between CD4 and CD8 immunogenicity in humans and animal species used in preclinical vaccine testing are yet to be fully understood. In this study, we addressed this matter by analyzing experimentally identified epitopes based on published data curated in the Immune Epitopes DataBase (IEDB) database. We first analyzed SARS-CoV-2 spike (S) and nucleoprotein (N), which are two common targets of the immune response and well studied in both human and mouse systems. We observed a weak but statistically significant correlation between human and H-2b mouse T-cell responses (CD8 S specific (r = 0.206, p = 1.37 × 10−13); CD4 S specific (r = 0.118, p = 2.63 × 10−5) and N specific (r = 0.179, p = 2.55 × 10−4)). Due to intrinsic differences in MHC molecules across species, we also investigated the association between the immunodominance of common Human Leukocyte Antigen (HLA) alleles for which HLA transgenic mice are available, namely, A*02:01, B*07:02, DRB1*01:01, and DRB1*04:01, and found higher significant correlations for both CD8 and CD4 (maximum r = 0.702, p = 1.36 × 10−31 and r = 0.594, p = 3.04−122, respectively). Our results further indicated that some regions are commonly immunogenic between humans and mice (either H-2b or HLA transgenic) but that others are human specific. Finally, we noted a significant correlation between CD8 and CD4 S- (r = 0.258, p = 7.33 × 1021) and N-specific (r = 0.369, p = 2.43 × 1014) responses, suggesting that discrete protein subregions can be simultaneously recognized by T cells. These findings were confirmed in other viral systems, providing general guidance for the use of murine models to test T-cell immunogenicity of viral antigens destined for human use.

A novel retinoic acid receptor-γ agonist antagonizes immune checkpoint resistance in lung cancers by altering the tumor immune microenvironment

All-trans-retinoic acid (ATRA), the retinoic acid receptors (RARs) agonist, regulates cell growth, differentiation, immunity, and survival. We report that ATRA-treatment repressed cancer growth in syngeneic immunocompetent, but not immunodeficient mice. The tumor microenvironment was implicated: CD8+ T cell depletion antagonized ATRA’s anti-tumorigenic effects in syngeneic mice. ATRA-treatment with checkpoint blockade did not cooperatively inhibit murine lung cancer growth. To augment ATRA’s anti-tumorigenicity without promoting its pro-tumorigenic potential, an RARγ agonist (IRX4647) was used since it regulates T cell biology. Treating with IRX4647 in combination with an immune checkpoint (anti-PD-L1) inhibitor resulted in a statistically significant suppression of syngeneic 344SQ lung cancers in mice—a model known for its resistance to checkpoints and characterized by low basal T cell and PD-L1 expression. This combined treatment notably elevated CD4+ T-cell presence within the tumor microenvironment and increased IL-5 and IL-13 tumor levels, while simultaneously decreasing CD38 in the tumor stroma. IL-5 and/or IL-13 treatments increased CD4+ more than CD8+ T-cells in mice. IRX4647-treatment did not appreciably affect in vitro lung cancer growth, despite RARγ expression. Pharmacokinetic analysis found IRX4647 plasma half-life was 6 h in mice. Yet, RARα antagonist (IRX6696)-treatment with anti-PD-L1 did not repress syngeneic lung cancer growth. Together, these findings provide a rationale for a clinical trial investigating an RARγ agonist to augment check point blockade response in cancers.

Local blockade of tacrolimus promotes T-cell-mediated tumor regression in systemically immunosuppressed hosts

BackgroundImmunosuppressive drugs such as tacrolimus have revolutionized our ability to transplant organs between individuals. Tacrolimus acts systemically to suppress the activity of T-cells within and around transplanted organs. However, tacrolimus...

Autologous CD19-Targeted Chimeric Antigen Receptor (CAR)T-Cells as the Future of Systemic Lupus Erythematosus Treatment.

Systemic lupus erythematosus (SLE) is a chronic autoimmune illness with an unclear etiology and a range of clinical manifestations. The therapeutic results of current conventional treatments are frequently unsatisfactory. Many B-cell-directed immunotherapies have recently been discovered, as B cells play a key role in the pathogenesis of SLE. However, large-scale rituximab trials found that the antibody against CD20 was no better than a placebo. Autologous CAR T-cell therapy has garnered considerable interest and is considered a potential treatment option for SLE. CD19+CD20- B cells are thought to play an essential role in the onset and progression of SLE. CD19-targeted CAR T-cells destroy B cells without requiring an accessory cell type, thereby decreasing B cells more efficiently. Preclinical trials of CAR T-cells in mice have shown promising results against SLE. The review aimed to shed light on autologous CD19-targeted CAR T-cells as a potential treatment for SLE.

206-OR: A Human Gut Commensal, Parabacteroides distasonis, Stimulates an Inflammatory Response Specific to the Pancreas but Not to the Intestines, and Induces Type 1 Diabetes

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by the destruction of pancreatic β-cells, resulting in insulin deficiency and hyperglycemia. Previous studies have shown that the gut microbiome is associated with the development and incidence of diabetes, however, the main trigger of T1D is unknown. Insulin protein epitopes are the primary targets of the T-cells, stimulating an autoimmune response against β-cells. We previously identified and characterized a bacterial peptide mimic of insulin B-chain 9-23 epitope (insB:9-23) in P. distasonis, a human gut commensal. This bacterial mimic, hprt4-18, is identified in the N-terminal of the hypoxanthine-guanine phosphoribosyltransferase protein. It activates both human T-cell clones and nonobese diabetic (NOD) mice T-cell hybridomas specific to insB:9-23. Reanalysis of DIABIMMUNE data confirms that exposure to hprt-4:18 in the first three years of life increases the risk of seropositivity. The colonization of female NOD mice's gut microbiome with P. distasonis accelerated the infiltration of T-cells into the islets and increased the incidence of T1D. In addition, P. distasonis colonization increased splenic CD4+ and CD8+ T-cells and decreased FoxP3+ Treg cells. Because the first interaction between the host immune system and gut microbes occurs in the intestines, we determined the direct effects of P. distasonis colonization on intestinal intraepithelial lymphocyte (IELs) composition. Notably, P. distasonis colonization decreased CD4+, CD4+ CD62L+ (Naïve), CD8+CD44+ (Effector), CD4+CD44+CD62L+ (Central) T-cell and B-cell populations. Taken together, these results support our molecular mimicry mechanism hypothesis as P. distasonis decrease inflammation in the intestines, however, induce an autoimmune response specific to pancreatic β-cells resulting in accelerated diabetes incidence in female NOD mice. Disclosure K.Girdhar: None. A.Raisingani: None. E.Altindis: None. Funding JDRF T1D (5112731); Mathers Foundation

Discovery of Potent, Dual-Inhibitors of Diacylglycerol Kinases Alpha and Zeta Guided by Phenotypic Optimization.

We describe a phenotypic screening and optimization strategy to discover compounds that block intracellular checkpoint signaling in T-cells. We identified dual DGKα and ζ inhibitors notwithstanding the modest similarity between α and ζ relative to other DGK isoforms. Optimized compounds produced cytokine release and T-cell proliferation consistent with DGK inhibition and potentiated an immune response in human and mouse T-cells. Additionally, lead inhibitor BMS-502 demonstrated dose-dependent immune stimulation in the mouse OT-1 model, setting the stage for a drug discovery program.

Phase 1b multicenter study to evaluate CHM 1101 in patients with recurrent or progressive glioblastoma.

TPS2086 Background: Glioblastoma multiforme (GBM) is the most common and most aggressive primary brain tumor. More than 300,000 new cases are diagnosed globally with over 250,000 deaths each year (Sung H, et al. CA Cancer J Clin. 2021). Patients with recurrent GBM have a poor prognosis, with limited treatment options and a median survival of less than 1 year (Gallego. Curr Oncol, 2015). While prior attempts to treat GBM with chimeric antigen receptor (CAR) T-cells have been limited by tumor heterogeneity, chlorotoxin (CLTX)-directed CAR T-cells in mice demonstrated broad anti-tumor activity and prolonged survival with no off-tumor toxicity or antigen escape (Wang, et al. Sci Transl Med, 2020). CLTX, a 36–amino acid peptide identified in scorpion venom, selectively binds to malignant glioma cells through matrix metalloproteinase-2 (MMP2) and clinical administration of CLTX-based biologics has been well tolerated in patients (Mamelak, et al. J Clin Oncol, 2005, Patil, et al. Neurosurgery, 2019). CHM 1101 is the first CAR T to utilize CLTX as its tumor targeting domain for autologous CAR T-cell therapy. A single-center first-in-human phase 1 study of CHM 1101 in patients with recurrent GBM is ongoing. Methods: Clinical Trial NCT05627323 is a phase 1b, multi-center study of CHM 1101 in adult subjects with MMP2+ recurrent or progressive GBM after standard therapy. After leukapheresis and tumor resection, pts will receive CHM 1101 at Dose Level 1 (240 × 106 CAR T cells) or Dose Level 2 (440 x 106d CAR T-cells), divided across 3 once-weekly intracranial (intracavitary and intraventricular) administrations; after disease assessment at 28 days, additional doses of CHM 1101 can be administered on a weekly schedule. Eligible subjects have a prior histologically confirmed diagnosis of a grade 4 GBM, a grade 2 or 3 malignant glioma with radiographic progression consistent with a grade 4 GBM (IDH wild type), grade 4 diffuse astrocytoma (IDH mutant), or a unifocal relapse of GBM. MMP2+ tumor expression is confirmed by IHC (≥20% moderate/high MMP2 score [2+ or 3+]). The primary endpoint is safety; key secondary endpoints include feasibility, progression-free survival, overall survival, response rate (RANO criteria), and cellular kinetics. Recruitment is ongoing. Clinical trial information: NCT05627323 .

Abstract ND04: BAY 2965501: A highly selective DGK- ζ inhibitor for cancer immuno-therapy with first-in-class potential

Abstract The second messenger diacyl glycerol (DAG) plays a key role in T cell receptor downstream signaling and thereby in T-cell activation. Diacylglycerol kinase zeta (DGK-ζ) is a lipid kinase that can down-modulate T-cell activation by catalyzing the conversion of DAG to phosphatidic acid, thereby acting as a ligand independent, intracellular immune checkpoint. Inhibition of DGK- ζ offers the potential to enhance T cell priming against suboptimal tumor antigens and to overcome multiple immune-suppressive mechanisms in the tumor microenvironment. Bayer AG in collaboration with the German Cancer Research Center (DKFZ) have developed BAY 2965501, a highly selective, orally available DGK-ζ inhibitor which shows a unique binding mode and good DMPK profile. The compound enhances the reactivity of human and mouse T-cells, both in the priming and the effector phase, and overcomes the inhibitory impact of suppressive factors, such as adenosine and prostaglandin E2. Oral dosing of BAY 2965501 shows T cell dependent efficacy in syngeneic, murine tumor models. Furthermore, this results in reactivation of exhausted T cells in vivo. Preclinical safety studies showed only mild findings, so that good clinical tolerability is expected. Collectively, the preclinical data support first in human (FiH) phase I testing of therapeutic potential. A FiH trial with BAY 2965501 in patients with advanced solid tumors including NSCLC, gastric/GEJ AdCa, ccRCC, and melanoma patients, is currently enrolling patients (NCT05614102). This study will evaluate the safety, tolerability, maximum tolerated or administered dose, pharmacokinetics, pharmacodynamics, and tumor response profile of BAY 2965501. Citation Format: Rienk Offringa, Catherine Olesch, Frederik Cichon, Mareike Grees, Norbert Schmees, Ulrike Roehn, Florian Prinz, Judith Guenther, Detlef Stoeckigt, Michael Erkelenz, Thi Thanh Uyen Nguyen, Ulf Boemer, Nicolas Werbeck, Marc Kunze, Kirstin Petersen, Dennis Kirchhoff. BAY 2965501: A highly selective DGK- ζ inhibitor for cancer immuno-therapy with first-in-class potential [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr ND04.

Abstract 2867: Ceramide-dependent mitophagy leads to metabolic reprogramming in aging T-cells associated with reduced anti-tumor T-cell functions

Abstract Changes in mitochondrial bioenergetics in aging T-cells play a key role in the decrease in T-cell function and tumor resistance with aging. The bioactive sphingolipid ceramide, induced by aging stress, is a major player in these changes, as its accumulation at the mitochondrial membranes of both mouse and human aging T-cells induces ceramide-dependent mitophagy, which decreases T-cell viability, cytokine secretion, and anti-tumor activity. Using knock-out mouse models and pharmacological inhibition, we show that C14-ceramide accumulation in the mitochondria and mitophagy in the T-cells of aging mice are dependent on Ceramide Synthase 6 (CerS6), an enzyme responsible for C14/C16-ceramide synthesis. Interestingly, sphingosine kinase 2 (SphK2), another enzyme involved in ceramide metabolism inhibits HDAC1/2 function in aging T-cells, epigenetically inducing CerS6 expression and the resultant ceramide-dependent mitophagy, which ultimately decreases T-cell anti-tumor function. Both CerS6-/- and SphK2-/- aging T-cells were protected from the reduction in T-cell function, and their anti-tumor function was maintained in adoptive-cell transfer experiments to mice with melanoma. Besides lipid signaling, other metabolic changes associated with this aging-induced process have not been explored, and the utility of correcting these metabolic changes to restore T-cell function has not been evaluated. We studied the total hydrophilic metabolome of aging T-cells undergoing ceramide-dependent mitophagy to assess the metabolic changes occurring in these cells. Our findings show a general depletion of tricarboxylic acid cycle (TCA) metabolites in aging T-cells, with pools of fumarate, malate, and argininosuccinate significantly decreasing in both mouse and human aging T-cells. Interestingly, these changes were mirrored by similar changes in human cancer cells undergoing ceramide-dependent mitophagy, suggesting that these changes might constitute a general metabolic signature for this specific mitophagy process with deleterious effects on anti-tumor functions of aging T-cells. Both in vitro and in vivo supplementation of fumarate to mouse T-cells seemed to correct some of the functional defects observed in aging, with a protection of T-cell viability, cytokine production, and tumor killing capacity in co-cultures with tumor cells. The fumarate supplementation also led to a decrease in ceramide-dependent mitophagy in the aging T-cells, indicating an interplay between ceramide-dependent mitophagy and fumarate metabolism. Overall, these studies help explain the mechanisms behind aging-related dysregulation of T-cell anti-tumor activity, which can be restored by inhibiting ceramide-dependent mitophagy by pharmacological and genetic tools or by reprogramming fumarate metabolism in aging T cells. Citation Format: Mohamed Faisal Kassir, Han Gyul Lee, Natalia Oleinik, Paramita Chakraborty, John J. Lemasters, Zdzislaw Szulc, Xue-Zhong Yu, Shikhar Mehrotra, Besim Ogretmen. Ceramide-dependent mitophagy leads to metabolic reprogramming in aging T-cells associated with reduced anti-tumor T-cell functions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2867.

Human lymphocytes mobilized with exercise have an anti-tumor transcriptomic profile and exert enhanced graft-versus-leukemia effects in xenogeneic mice.

Every bout of exercise mobilizes and redistributes large numbers of effector lymphocytes with a cytotoxic and tissue migration phenotype. The frequent redistribution of these cells is purported to increase immune surveillance and play a mechanistic role in reducing cancer risk and slowing tumor progression in physically active cancer survivors. Our aim was to provide the first detailed single cell transcriptomic analysis of exercise-mobilized lymphocytes and test their effectiveness as a donor lymphocyte infusion (DLI) in xenogeneic mice engrafted with human leukemia. Peripheral blood mononuclear cells (PBMCs) were collected from healthy volunteers at rest and at the end of an acute bout of cycling exercise. Flow cytometry and single-cell RNA sequencing was performed to identify phenotypic and transcriptomic differences between resting and exercise-mobilized cells using a targeted gene expression panel curated for human immunology. PBMCs were injected into the tail vein of xenogeneic NSG-IL-15 mice and subsequently challenged with a luciferase tagged chronic myelogenous leukemia cell line (K562). Tumor growth (bioluminescence) and xenogeneic graft-versus-host disease (GvHD) were monitored bi-weekly for 40-days. Exercise preferentially mobilized NK-cell, CD8+ T-cell and monocyte subtypes with a differentiated and effector phenotype, without significantly mobilizing CD4+ regulatory T-cells. Mobilized effector lymphocytes, particularly effector-memory CD8+ T-cells and NK-cells, displayed differentially expressed genes and enriched gene sets associated with anti-tumor activity, including cytotoxicity, migration/chemotaxis, antigen binding, cytokine responsiveness and alloreactivity (e.g. graft-versus-host/leukemia). Mice receiving exercise-mobilized PBMCs had lower tumor burden and higher overall survival (4.14E+08 photons/s and 47%, respectively) at day 40 compared to mice receiving resting PBMCs (12.1E+08 photons/s and 22%, respectively) from the same donors (p<0.05). Human immune cell engraftment was similar for resting and exercise-mobilized DLI. However, when compared to non-tumor bearing mice, K562 increased the expansion of NK-cell and CD3+/CD4-/CD8- T-cells in mice receiving exercise-mobilized but not resting lymphocytes, 1-2 weeks after DLI. No differences in GvHD or GvHD-free survival was observed between groups either with or without K562 challenge. Exercise in humans mobilizes effector lymphocytes with an anti-tumor transcriptomic profile and their use as DLI extends survival and enhances the graft-versus-leukemia (GvL) effect without exacerbating GvHD in human leukemia bearing xenogeneic mice. Exercise may serve as an effective and economical adjuvant to increase the GvL effects of allogeneic cell therapies without intensifying GvHD.

457 CD39 Expression in the Glioblastoma Microenvironment does not Affect T Cell Exhaustion or Survival

INTRODUCTION: Glioblastoma (GBM), the most common malignant brain tumor, is notable for its dysfunctional T-cells. The initial optimism of Immune checkpoint inhibitors has been tempered as these agents have not been successful in treating GBM. CD39 is the first enzyme in the breakdown of ATP to adenosine and is highly upregulated in GBM. CD39 is also thought to contribute to T-cell exhaustion. However, inhibiting the CD39 ATP breakdown pathway did not improve survival in mice, even with PD-1 inhibition, leading to uncertainty about whether non-enzymatic functions of CD39 give it a role in T-cell exhaustion in GBM. METHODS: We performed intracranial injections of SB28 and GL261 GBM cell lines into CD39 global nulls (KO) and C57BL/6J (WT) mice and measured survival. Another cohort of mice were similarly injected and sacrificed after 2 weeks. These tumors were analyzed for T-cell exhaustion markers using flow cytometry. RESULTS: There was no survival benefit seen in either cell line when compared to wild type mice. The immune cell profile was not found to be statistically different between KO and WT mice. Next, expression of known exhaustion markers such as PD-1, TIM3, and LAG3 on tumor infiltrating lymphocytes (TILs) were analyzed. Expression of TIM3 and 2B4 were found to be increased in CD39KO TILs compared to WT (p &lt; 0.01). Additionally, numerous exhaustion markers such as LAG3, TIGIT, and CTLA4 were decreased on TILs compared to peripheral blood T-cells in tumor-bearing mice (p &lt; 0.01). CONCLUSIONS: These results suggest that CD39 lacks a direct impact on GBM outcomes but may affect the expression of other exhaustion markers. Further studies will continue to investigate the interaction between immune checkpoint molecules in GBM.