Treg Suppression Research Articles

Abstract 5306: PTPN22 targeting partners with 41BB/OX40 costimulation to overcome anti-PD1 resistance in pancreatic ductal adenocarcinoma

Abstract Background: The pancreatic ductal adenocarcinoma (PDAC) tumor microenvironment (TME) is notable for a scarcity of cytotoxic T cells and an overabundance of immunosuppressive myeloid and regulatory T cells. Checkpoint immunotherapies targeting PD/L1 or CTLA4 have shown efficacy in immunogenic cancers but remain ineffective in PDAC, highlighting a need for novel approaches. Abrogating protein tyrosine phosphatase non-receptor type 22 (PTPN22), a phosphatase in the TCR signaling cascade, has been shown to modulate multiple mechanisms of immune resistance. Furthermore, 41BB costimulatory pathway has recently been investigated as a potential strategy to enhance immunotherapy against PDAC. Using immune-resistant murine models of PDAC, we investigated PTPN22 as an immunotherapeutic target in combination with 41BB co-stimulation and PD1 inhibition against PDAC. Methods: We employed a well-characterized murine PDAC cell line expressing mutant KrasG12D and Trp53R172H under the Pdx1-cre promoter (KPCY 6419c5). This tumor line is resistant to combination immuno- and chemotherapies. To determine treatment efficacy, PTPN22 deficient mice (KO) were inoculated with KPCY6419c5 cells either subcutaneously or orthotopically into the pancreas. To extend the translatability of PTPN22 targeting, we also injected PTPN22 competent mice with the same tumor cells and treated them with our novel PTPN22 inhibitor L1. Harvested tumors were processed for FFPE and mass cytometry (CyTOF) analysis to track changes in the immune compartment. Results: When PTPN22 was abrogated, treatment with anti-PD1 and 41BB agonism led to a 10-day delay in substantial tumor formation and roughly 75% reduction in tumor volume by 21-days post treatment. These tumors showed elevated levels of OX40 and OX40L primarily in the setting of PTPN22 KO/PD1/41BB therapy. In a subsequent in vivo experiment using an OX40L neutralizing antibody, we found that OX40 signaling is essential for the efficacy of PTPN22 KO/PD1/41BB therapy. Furthermore, combining OX40 agonist with anti-PD1 in PTPN22 KO sufficiently mimicked the efficacy seen with the anti-PD-1 and 41BB combination. CyTOF analysis indicated that OX40 expression is enriched in Tregs and OX40L is enriched in myeloid derived suppressor cells (MDSCs). Moreover, combination therapy efficacy was reproduced using the PTPN22 inhibitor L1. Conclusions: PTPN22 abrogation enhances the success of PD-1 inhibition given with either OX-40 or 41BB agonist therapies. In addition, PTPN22 abrogation together with PD1 inhibition and 41BB costimulation reduces MDSC and Treg suppression of effector T cells via the OX40L-OX40 axis. Finally, PTPN22 can be blocked by a small molecule inhibitor strengthening its candidacy as a therapeutic target. Citation Format: Soren Charmsaz, Nicole E. Gross, Jae W. Lee, Jianping Lin, Alexei G. Hernandez, Erin M. Coyne, Sarah M. Shin, Courtney Cannon, Xuan Yuan, Zhong-Yin Zhang, Elizabeth M. Jaffee, Won Jin Ho. PTPN22 targeting partners with 41BB/OX40 costimulation to overcome anti-PD1 resistance in pancreatic ductal adenocarcinoma [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 5306.

Abstract 90: In vitro functional evaluation of immuno-oncology drug candidates in customized bioassays

Abstract Increased understanding of the complex tumor microenvironment and its interactors has boosted therapeutic interest and highlighted the importance of the development of innovative in vitro bioassays to represent all the players of the cancer immune response and thereby potentially provide pivotal information on the functional dynamics of candidate therapeutics. Regulatory T cells play an important role by downregulating the anti-tumor response. Their regulation mechanisms constitute an important target for new therapeutics. To study these mechanisms in a human model, suppressive Treg bioassays, mimicking the suppressive action of these cells, were developed and optimized. We further highlight the study of neutrophil function in vitro using flow-cytometry or the Incucyte® live imaging system to monitor neutrophil functions such as antibody-dependent cell-mediated cytotoxicity (ADCC), Neutrophil Extracellular Traps (NETs) formation and the release of Reactive Oxygen Species (ROS). Additionally, multiplex cytokine and peroxidase enzyme analysis after activation and stimulation of neutrophils can be evaluated using ELISA or Luminex technology. Moreover, to refine/reduce non-human primate (NHP) usage, we aimed to develop cost-effective NHP in vitro assays with predictive value for in vivo studies. We isolated Cynomolgus Macaque monocytes and successfully differentiated/polarized them into M0- and M2-like macrophages with a cell surface phenotype comparable to that of their human counterparts. We further developed a Cynomolgus Macaque PBMC x human dendritic cell (DC) mixed lymphocyte reaction (MLR) assay for functional evaluation of test compounds, effectively generated Cynomolgus Macaque immature DCs and implemented Cynomolgus Macaque cytokine release assays.Using high quality primary human immune cells from our own biobank, in vitro bioassays have been developed with superior robustness and reproducibility to screen candidate Immuno-Oncology therapeutics. Citation Format: Martijn Vlaming, Emmanuelle Sidot, Jezabel Lefèvre, Ellen Boelen, Sofie Pattyn. In vitro functional evaluation of immuno-oncology drug candidates in customized bioassays [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 90.

Abstract 4512: Discovery of highly potent, selective, and orally bioavailable IKZF2 degrader and its anti-tumor activity in syngeneic mouse models

Abstract Molecular glue degraders (MGDs) are emerging as innovative therapeutic modalities, owing to their efficacy in targeting previously undruggable targets. MGDs induce close proximity between the target protein and E3 ligase, resulting in the degradation of the target protein. In the wake of the remarkable success of PD-1/PD-L1 inhibitors, various approaches to modulate the activity of regulatory T cells (Tregs) activity have been explored. Tregs represent the primary immune suppressor and significantly impede antitumor immune responses. IKZF2, a marker of stable suppressive Treg, is essential for maintaining the stable Treg cell phenotype. Depletion of IKZF2 can induce a transition from Treg to effector T cell (Teff) phenotypes, thereby enhancing anti-tumor responses. Leveraging an Immunomodulatory drug (IMiD), Novartis has developed the IKZF2 degrader DKY709, which is currently undergoing Phase I clinical trials, both as a monotherapy and in combination with a PD-1 immune checkpoint inhibitor. In this presentation, we present the preclinical results of the best-in-class IKZF2 degrader, PRT-101. PRT-101 elicits rapid and robust degradation of IKZF2, demonstrating subnanomolar DC50 and achieving 100% Dmax in a proteasome- and CRBN-dependent manner. However, PRT-101 does not induce the degradation of well-known neosubstrates, including IKZF1, IKZF3, SALL4, and CK1a. Global proteomic analysis reveals that PRT-101 exclusively facilitates IKZF2 degradation. The degradation of IKZF2 by PRT-101results in an increase in IL-2 secretion, a marker of T effector function. Furthermore, oral administration of PRT-101 exhibits excellent pharmacokinetics, concurrent with IKZF2 degradation, yielding superior anti-tumor effects compared to DKY709 in the MC38 mouse syngeneic model. In conclusion, our findings underscore the potential of the novel IKZF2 degrader as a promising immuno-oncology target for the treatment of solid tumors. Citation Format: Seulki Park, Jeong Hee Moon, Gaseul Lee, Hyun Jin Kim, Jeong-Hoon Kim, Jong Yeon Hwang. Discovery of highly potent, selective, and orally bioavailable IKZF2 degrader and its anti-tumor activity in syngeneic mouse models [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 4512.

Abstract 6860: Fluorescent tracking reveals that radiation therapy influences the migration and plasticity of Tregs within the tumor microenvironment

Abstract Radiation therapy (RT) has long been a cornerstone in cancer treatment, yet the mechanisms underlying its impact on the immune system remain incompletely understood. RT is recognized for its ability to induce DNA damage within cancer cells, leading to cancer cell death. For those cancer cells that do not die as a result of radiation, tumor infiltration by immune cells is closely associated with treatment outcomes. T cell infiltration is a dynamic process, with subsets taking up residence in the tumor while the majority recirculate through lymph nodes into the peripheral blood. T regulatory cells (Tregs) have been recognized as potent suppressors of anti-tumor immune responses, dampening immune-mediated clearance of cancer cells. While RT can initially contribute to an improved anti-tumor immune response, this beneficial effect is often counterbalanced by the presence of suppressive Tregs. Tregs can infiltrate the tumor microenvironment, ultimately impeding and overwhelming the immune response generated by RT. Our objective was to gain insights into the migratory patterns of Tregs to and from tumor sites and to elucidate how RT influences the dynamics of Treg recirculation. Utilizing the established photoconvertible Kaede mouse model we can track photoconverted cells following RT. Following photoconversion, photoconverted T cells were observable within the tumor and subsequently moved to the TdLN and on to other NdLN at later time points. In the TdLN of mice bearing MC38, Moc1, and Moc2 tumors, Tregs represented a significantly higher proportion of photoconverted cells compared to non-Treg CD4 or CD8 T cells. To validate their active departure from the tumor site, mice underwent FTY720 treatment, resulting in a reduction in both photoconverted Treg and non-Treg migration to the TdLN. When RT was administered to the tumor, there was a decrease in photoconverted Treg and non-Treg CD4 T cells within the TdLN, consistent with the expected cytotoxic effects on the irradiated tumor upstream. To focus on recruitment back from the TdLN, mice were analyzed after photoconversion of the TdLN. This revealed that a majority of TdLN Tregs exhibited a preference for relocating to the tumor, with only a minority migrating to the NdLN. The newly entered Tregs were analyzed in the tumor, at D1 and D3 post RT, and we found that these Tregs exhibited increased expression of CCR8, CD69, KLRG1 and Ly6C as compared to those in non-irradiated tumors, suggesting that these are recent entrants with limited suppressive capacity. These findings illuminate the intricate dynamics between RT, Tregs, and the use of site-specific photoconversion to track immune cell movement and changes over time to understand treatment responses. Our ongoing studies focus on the interplay between the Treg and the tumor environment that dictates the success of CD8 T cell mediated control of residual cancer cells following RT. Citation Format: David J. Friedman, Tiffany Blair, Gwen Kramer, Aanchal Preet Kaur, Jason Baird, Alejandro Alice, Megan Potuznik, Marka R. Crittenden, Michael J. Gough. Fluorescent tracking reveals that radiation therapy influences the migration and plasticity of Tregs within the tumor microenvironment [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 6860.

Targeting tumor-infiltrating tregs for improved antitumor responses.

Immunotherapies have revolutionized the landscape of cancer treatment. Regulatory T cells (Tregs), as crucial components of the tumor immune environment, has great therapeutic potential. However, nonspecific inhibition of Tregs in therapies may not lead to enhanced antitumor responses, but could also trigger autoimmune reactions in patients, resulting in intolerable treatment side effects. Hence, the precision targeting and inhibition of tumor-infiltrating Tregs is of paramount importance. In this overview, we summarize the characteristics and subpopulations of Tregs within tumor microenvironment and their inhibitory mechanisms in antitumor responses. Furthermore, we discuss the current major strategies targeting regulatory T cells, weighing their advantages and limitations, and summarize representative clinical trials targeting Tregs in cancer treatment. We believe that developing therapies that specifically target and suppress tumor-infiltrating Tregs holds great promise for advancing immune-based therapies.

Adjuvant Novel Nanocarrier-Based Targeted Therapy for Lung Cancer.

Lung cancer has the lowest survival rate due to its late-stage diagnosis, poor prognosis, and intra-tumoral heterogeneity. These factors decrease the effectiveness of treatment. They release chemokines and cytokines from the tumor microenvironment (TME). To improve the effectiveness of treatment, researchers emphasize personalized adjuvant therapies along with conventional ones. Targeted chemotherapeutic drug delivery systems and specific pathway-blocking agents using nanocarriers are a few of them. This study explored the nanocarrier roles and strategies to improve the treatment profile's effectiveness by striving for TME. A biofunctionalized nanocarrier stimulates biosystem interaction, cellular uptake, immune system escape, and vascular changes for penetration into the TME. Inorganic metal compounds scavenge reactive oxygen species (ROS) through their photothermal effect. Stroma, hypoxia, pH, and immunity-modulating agents conjugated or modified nanocarriers co-administered with pathway-blocking or condition-modulating agents can regulate extracellular matrix (ECM), Cancer-associated fibroblasts (CAF),Tyro3, Axl, and Mertk receptors (TAM) regulation, regulatory T-cell (Treg) inhibition, and myeloid-derived suppressor cells (MDSC) inhibition. Again, biomimetic conjugation or the surface modification of nanocarriers using ligands can enhance active targeting efficacy by bypassing the TME. A carrier system with biofunctionalized inorganic metal compounds and organic compound complex-loaded drugs is convenient for NSCLC-targeted therapy.

Calycosin enhances Treg differentiation for alleviating skin inflammation in atopic dermatitis

Ethnopharmacological relevanceAtopic dermatitis (AD) is a prevalent chronic inflammatory skin disorder that poses a significant global health challenge. There is a lack of safe and effective medications to treat AD. Astragalus membranaceous is a traditional Chinese medicine widely used in clinical treatment of skin diseases. Calycosin (CA), derived from the root of Astragalus membranaceous, exhibits dual attributes of anti-inflammatory and antioxidant properties, suggesting its promise for addressing cutaneous inflammation. Nonetheless, the precise mechanisms underlying CA's therapeutic actions in AD remain elusive. Aim of the studyThis study aimed to evaluate the efficacy and safety of CA in treating AD while also delving into the mechanistic underpinnings of CA's action in AD. Materials and methodsThe cell viability and anti-inflammatory impacts of CA in vitro were first gauged using CCK-8 and RT-qPCR. The potential mechanisms of CA were then probed using modular pharmacology. Flow cytometry was employed to ascertain the differentiation of Treg and Th17 cells derived from naïve T cells, as well as the proportions and mean fluorescence intensity (MFI) of human iTreg cells. The expressions of IL-10 and TGF-β1 were measured and Treg suppression assay was performed. The in vivo therapeutic efficacy of topical CA application was assessed using a calcipotriol (MC903)-induced AD mouse model. The expression metrics of inflammatory cytokines, IL-17A, FOXP3, and RORγt were authenticated via immunohistochemistry, RT-qPCR, Western blot, and ELISA. ResultsCA exhibited a favorable safety profile and reduced the mRNA expressions of Th2 inflammatory cytokines in HaCaT cells. Modular pharmacology analysis pinpointed Th17 differentiation as the pivotal mechanism behind CA's therapeutic effect on AD. In vitro, CA fostered the differentiation of naïve T cells into Tregs while inhibiting their differentiation into Th17 cells. Furthermore, CA augmented the proliferation of human iTregs. In vivo, CA alleviated skin manifestations and decreased the levels of inflammatory mediators (IL-4, IL-5, IL-13, TSLP, and NF-κB related cytokines) in AD-like mouse models. Simultaneously, it regulated Treg/Th17 balance through suppressing IL-17A and RORγt expressions and bolstering FOXP3 expression. ConclusionsThe study provides insights into the mechanistic pathways through which CA exerts its anti-inflammatory effects, particularly through promoting Treg cell differentiation and inhibiting Th17 cell differentiation. Furthermore, CA emerges as an alternative or adjunctive treatment strategy for managing AD.

β-Carotene accelerates the resolution of atherosclerosis in mice

β-Carotene oxygenase 1 (BCO1) catalyzes the cleavage of β-carotene to form vitamin A. Besides its role in vision, vitamin A regulates the expression of genes involved in lipid metabolism and immune cell differentiation. BCO1 activity is associated with the reduction of plasma cholesterol in humans and mice, while dietary β-carotene reduces hepatic lipid secretion and delays atherosclerosis progression in various experimental models. Here we show that β-carotene also accelerates atherosclerosis resolution in two independent murine models, independently of changes in body weight gain or plasma lipid profile. Experiments in Bco1-/- mice implicate vitamin A production in the effects of β-carotene on atherosclerosis resolution. To explore the direct implication of dietary β-carotene on regulatory T cells (Tregs) differentiation, we utilized anti-CD25 monoclonal antibody infusions. Our data show that β-carotene favors Treg expansion in the plaque, and that the partial inhibition of Tregs mitigates the effect of β-carotene on atherosclerosis resolution. Our data highlight the potential of β-carotene and BCO1 activity in the resolution of atherosclerotic cardiovascular disease.

β-Carotene accelerates the resolution of atherosclerosis in mice.

β-Carotene oxygenase 1 (BCO1) catalyzes the cleavage of β-carotene to form vitamin A. Besides its role in vision, vitamin A regulates the expression of genes involved in lipid metabolism and immune cell differentiation. BCO1 activity is associated with the reduction of plasma cholesterol in humans and mice, while dietary β-carotene reduces hepatic lipid secretion and delays atherosclerosis progression in various experimental models. Here we show that β-carotene also accelerates atherosclerosis resolution in two independent murine models, independently of changes in body weight gain or plasma lipid profile. Experiments in Bco1-/- mice implicate vitamin A production in the effects of β-carotene on atherosclerosis resolution. To explore the direct implication of dietary β-carotene on regulatory T cells (Tregs) differentiation, we utilized anti-CD25 monoclonal antibody infusions. Our data show that β-carotene favors Treg expansion in the plaque, and that the partial inhibition of Tregs mitigates the effect of β-carotene on atherosclerosis resolution. Our data highlight the potential of β-carotene and BCO1 activity in the resolution of atherosclerotic cardiovascular disease.

Regulatory T cells suppress myeloma-specific immunity during autologous stem cell mobilization and transplantation

AbstractAutologous stem cell transplantation (ASCT) is the standard of care consolidation therapy for eligible patients with myeloma but most patients eventually progress, an event associated with features of immune escape. Novel approaches to enhance antimyeloma immunity after ASCT represent a major unmet need. Here, we demonstrate that patient-mobilized stem cell grafts contain high numbers of effector CD8 T cells and immunosuppressive regulatory T cells (Tregs). We showed that bone marrow (BM)-residing T cells are efficiently mobilized during stem cell mobilization (SCM) and hypothesized that mobilized and highly suppressive BM-derived Tregs might limit antimyeloma immunity during SCM. Thus, we performed ASCT in a preclinical myeloma model with or without stringent Treg depletion during SCM. Treg depletion generated SCM grafts containing polyfunctional CD8 T effector memory cells, which dramatically enhanced myeloma control after ASCT. Thus, we explored clinically tractable translational approaches to mimic this scenario. Antibody-based approaches resulted in only partial Treg depletion and were inadequate to recapitulate this effect. In contrast, a synthetic interleukin-2 (IL-2)/IL-15 mimetic that stimulates the IL-2 receptor on CD8 T cells without binding to the high-affinity IL-2Ra used by Tregs efficiently expanded polyfunctional CD8 T cells in mobilized grafts and protected recipients from myeloma progression after ASCT. We confirmed that Treg depletion during stem cell mobilization can mitigate constraints on tumor immunity and result in profound myeloma control after ASCT. Direct and selective cytokine signaling of CD8 T cells can recapitulate this effect and represent a clinically testable strategy to improve responses after ASCT.

P1223 Lactobacillus rhamnosus GG/p40 encapsuled cationic host defense peptide play protective roles on immune-related colitis by inducing differentiation and immune suppression of regulatory T cells

Abstract Background The immune-related colitis (IRC) is the most prominent in immune-related adverse events (irAE). The association between gut microbiota and IRC development has been revealed. Our study aimed to explore the protective effect and mechanism of the probiotic Lactobacillus rhamnosus GG (LGG) and its secretory protein p40 on IRC. The self-assembled cationic host defense peptide (CHDP) hydrogel was applied to protect oral p40 protein from digestive damage and target enriched the site of colitis. Methods The IRC model mice were intervened with LGG by gavage (i.g.), p40 by enema (en.), or p40 encapsuled by CHDP (i.g.). The T cell phenotype of colonic lamina propria mononuclear cells (LPMC) was measured by flow cytometry. The indocyanine green (ICG) encapsuled by CHDP was gavage in IRC model mice, the distribution of CHDP was monitored by fluorescence signals imaging via IVIS, to assess the adhesive effect of CHDP in mice colitis. In vitro, the proportion of regulatory T cells (Treg) differentiated was measured by LGG supernatant co-cultured with CD4+ naïve T cells, and the division index of CD4+T cells was measured by LGG supernatant co-cultured with CD4+T cells and Treg (CD4+T cells: Treg=1:1) by carboxyfluorescein succinimidyl ester (CFSE) staining test. Results Compared with DSS+anti-PD-1+anti-CTLA-4 IRC model group, LGG (i.g.) group had lower weight loss, DAI score, histopathological score, relative IL-6 and TNF-α mRNA level, IL-6 and TNF-α concentration and higher colon length (P<0.05) (Fig.1A-L). P40 (en.) group had lower weight loss, DAI score, histopathological score and higher colon length (P<0.05) (Fig.1M-T). CHDP+p40 (i.g.) group had lower weight loss, DAI score, histopathological score, relative IL-6 and TNF-α mRNA level, IL-6 concentration and higher colon length (P<0.05) (Fig.1M-W). The percentages of CD25+FoxP3+Treg/CD4+T cells of colonic LPMC in LGG, p40 (en.), and CHDP+p40 (i.g.) group were significantly higher than IRC model group (P<0.05) (Fig.1X-Z, α). The average 28hr-residual rate of fluorescence imaging radiance in IRC-CHDP+ICG group was higher than both NC-CHDP+ICG and IRC-ICG group (Fig.2β-δ), and the average radiance of colon in IRC-CHDP+ICG group was also the highest (P<0.05) (Fig.2ε-ζ). In vitro, LGG 107 CFU/mL, 108 CFU/mL and 5 × 108 CFU/mL (P<0.05) could significantly promote Treg differentiation with concentration dependent manner (Fig.2η-ι), and the suppression of Treg on CD4+T cells with lower division index compared with control group (Fig.2κ). Conclusion LGG/p40 played protective role by promoting the differentiation and immune suppression of Treg cells in IRC. CHDP hydrogel could protect p40 protein from the digestive damage, and target enriched the inflamed lesion to improve the efficacy.

Targeting the activin receptor 1C on CD4+ T cells for cancer immunotherapy

ABSTRACT Activins, members of the TGF-beta superfamily, have been isolated and identified in the endocrine system, but have not been substantially investigated in the context of the immune system and endocrine-unrelated cancers. Here, we demonstrated that tumor-bearing mice had elevated systemic activin levels, which correlated directly with tumor burden. Likewise, cancer patients have elevated plasma activin levels compared to healthy controls. We observed that both tumor and immune cells could be sources of activins. Importantly, our in vitro studies suggest that activins promote differentiation of naïve CD4+ cells into Foxp3-expressing induced regulatory T cells (Tregs), particularly when TGF-beta was limited in the culture medium. Database and qRT-PCR analysis of sorted major immune cell subsets in mice revealed that activin receptor 1c (ActRIC) was uniquely expressed on Tregs and that both ActRIC and ActRIIB (activin receptor 2b) were highly upregulated during iTreg differentiation. ActRIC-deficient naïve CD4+ cells were found to be defective in iTreg generation both in vitro and in vivo. Treg suppression assays were also performed, and ActRIC deficiency did not change the function or stability of iTregs. Mice lacking ActRIC or mice treated with monoclonal anti-ActRIC antibody were more resistant to tumor progression than wild-type controls. This phenotype was correlated with reduced expression of Foxp3 in CD4+ cells in the tumor microenvironment. In light of the information presented above, blocking activin-ActRIC signaling is a promising and disease-specific strategy to impede the accumulation of immunosuppressive iTregs in cancer. Therefore, it is a potential candidate for cancer immunotherapy.

Blocking tumor-platelet crosstalk to prevent tumor metastasis via reprograming glycolysis using biomimetic membrane-hybridized liposomes

Activated platelets promote tumor progression and metastasis through active interactions with cancer cells, especially in promoting epithelial-mesenchymal transition (EMT) of tumor cells and shedding tumor cells into the blood. Blocking platelet-tumor cell interactions can be a potential strategy to inhibit tumor metastasis. Platelet activation requires energy produced from aerobic glycolysis. Based on this, we propose a platelet suppression strategy by reprogramming glucose metabolism of platelets, which has an advantage over conventional antiplatelet treatment that has a risk of serious hemorrhage. We develop a biomimetic delivery system using platelet membrane-hybridized liposomes (PM-Lipo) for codelivery of quercetin and shikonin to simultaneously inhibit lactate transporter MCT-4 and a glycolytic enzyme PKM2 for achieving metabolic reprogramming of platelets and suppressing platelet activation. Notably, PM-Lipo can also inhibit glycolysis in cancer cells, which actually takes “two-birds-one-stone” action. Consequently, the platelet-tumor cell interactions are inhibited. Moreover, PM-Lipo can bind with circulating tumor cells and reduce their seeding in the premetastatic microenvironment. The in vivo studies further demonstrated that PM-Lipo can effectively suppress primary tumor growth and reduce lung metastasis without affecting inherited functions of platelets. Reprogramming glycolysis of platelets can remodel the tumor immune microenvironment, including suppression of Treg and stimulation of CTLs.

Downregulation of TCF7 and LEF1 is a key determinant of tumor-infiltrating regulatory T-cell function.

Forkhead box P3 (Foxp3)-expressing regulatory T (Treg) cells play essential roles in immune homeostasis but also contribute to establish a favorable environment for tumor growth by suppressing anti-tumor immune responses. It is thus necessary to specifically target tumor-infiltrating Treg cells to minimize effects on immune homeostasis in cancer immunotherapy. However, molecular features that distinguish tumor-infiltrating Treg cells from those in secondary lymphoid organs remain unknown. Here we characterize distinct features of tumor-infiltrating Treg cells by global analyses of the transcriptome and chromatin landscape. They exhibited activated phenotypes with enhanced Foxp3-dependent transcriptional regulation, yet being distinct from activated Treg cells in secondary lymphoid organs. Such differences may be attributed to the extensive clonal expansion of tumor-infiltrating Treg cells. Moreover, we found that TCF7 and LEF1 were specifically downregulated in tumor-infiltrating Treg cells both in mice and humans. These factors and Foxp3 co-occupied Treg suppressive function-related gene loci in secondary lymphoid organ Treg cells, whereas the absence of TCF7 and LEF1 accompanied altered gene expression and chromatin status at these gene loci in tumor-infiltrating Treg cells. Functionally, overexpression of TCF7 and LEF1 in Treg cells inhibited the enhancement of Treg suppressive function upon activation. Our results thus show the downregulation of TCF7 and LEF1 as markers of highly suppressive Treg cells in tumors and suggest that their absence controls the augmentation of Treg suppressive function in tumors. These molecules may be potential targets for novel cancer immunotherapy with minimum effects on immune homeostasis.

Targets specific to certain Treg cell types in the TME of pancreatic cancer

The increased content of Treg cells in the pancreatic cancer TME shows the development of pancreatic cancer is largely influenced by treg cells. Regulatory T cells (Treg) have a powerful immune suppression function, under normal circumstances, have the function of maintaining autoimmune tolerance. When Treg cells expressing abnormally in tumor tissue, they can inhibit normal anti-tumor immune response, accelerate the immune escape in tumor cells, promote tumor growth. Meanwhile, Treg can also inhibit tumor growth through anti-inflammatory and anti-angiogenesis routes. Blind killing and inhibition of Treg will destroy the maintenance of the body's self-immune tolerance and cause some damage. In this paper, the duality of Treg cells is summarized through two aspects, including the summary analysis of specific targets on different types of Treg cells in TME to find the targets that can specifically kill immunosuppressive Treg cells; discuss the interactions between Treg cells and their surrounding cells, and their relationship with the duality of Treg cells, in order to provide the basis for reducing damage and optimizing immunotherapy during immunotherapy.

Interferon regulatory factor 4 plays a pivotal role in the development of aGVHD-associated colitis

ABSTRACT Interferon regulatory factor 4 (IRF4) is a master transcription factor that regulates T helper cell (Th) differentiation. It interacts with the Basic leucine zipper transcription factor, ATF-like (BATF), depletion of which in CD4+ T cells abrogates acute graft-versus-host disease (aGVHD)-induced colitis. Here, we investigated the immune-regulatory role of Irf4 in a mouse model of MHC-mismatched bone marrow transplantation. We found that recipients of allogenic Irf4 -/- CD4+ T cells developed less GVHD-related symptoms. Transcriptome analysis of re-isolated donor Irf4 -/- CD4+ T helper (Th) cells, revealed gene expression profiles consistent with loss of effector T helper cell signatures and enrichment of a regulatory T cell (Treg) gene expression signature. In line with these findings, we observed a high expression of the transcription factor BTB and CNC homolog 2; (BACH2) in Irf4 -/- T cells, which is associated with the formation of Treg cells and suppression of Th subset differentiation. We also found an association between BACH2 expression and Treg differentiation in patients with intestinal GVHD. Finally, our results indicate that IRF4 and BACH2 act as counterparts in Th cell polarization and immune homeostasis during GVHD. In conclusion, targeting the BACH2/IRF4-axis could help to develop novel therapeutic approaches against GVHD.

CD4+ T-Cell Legumain Deficiency Attenuates Hypertensive Damage via Preservation of TRAF6.

T cells are central to the immune responses contributing to hypertension. LGMN (legumain) is highly expressed in T cells; however, its role in the pathogenesis of hypertension remains unclear. Peripheral blood samples were collected from patients with hypertension, and cluster of differentiation (CD)4+ T cells were sorted for gene expression and Western blotting analysis. TLGMNKO (T cell-specific LGMN-knockout) mice (Lgmnf/f/CD4Cre), regulatory T cell (Treg)-specific LGMN-knockout mice (Lgmnf/f/Foxp3YFP Cre), and RR-11a (LGMN inhibitor)-treated C57BL/6 mice were infused with Ang II (angiotensin II) or deoxycorticosterone acetate/salt to establish hypertensive animal models. Flow cytometry, 4-dimensional label-free proteomics, coimmunoprecipitation, Treg suppression, and in vivo Treg depletion or adoptive transfer were used to delineate the functional importance of T-cell LGMN in hypertension development. LGMN mRNA expression was increased in CD4+ T cells isolated from hypertensive patients and mice, was positively correlated with both systolic and diastolic blood pressure, and was negatively correlated with serum IL (interleukin)-10 levels. TLGMNKO mice exhibited reduced Ang II-induced or deoxycorticosterone acetate/salt-induced hypertension and target organ damage relative to wild-type (WT) mice. Genetic and pharmacological inhibition of LGMN blocked Ang II-induced or deoxycorticosterone acetate/salt-induced immunoinhibitory Treg reduction in the kidneys and blood. Anti-CD25 antibody depletion of Tregs abolished the protective effects against Ang II-induced hypertension in TLGMNKO mice, and LGMN deletion in Tregs prevented Ang II-induced hypertension in mice. Mechanistically, endogenous LGMN impaired Treg differentiation and function by directly interacting with and facilitating the degradation of TRAF6 (tumor necrosis factor receptor-associated factor 6) via chaperone-mediated autophagy, thereby inhibiting NF-κB (nuclear factor kappa B) activation. Adoptive transfer of LGMN-deficient Tregs reversed Ang II-induced hypertension, whereas depletion of TRAF6 in LGMN-deficient Tregs blocked the protective effects. LGMN deficiency in T cells prevents hypertension and its complications by promoting Treg differentiation and function. Specifically targeting LGMN in Tregs may be an innovative approach for hypertension treatment.

Abstract C064: Combination of D3L-002, an anti-TIGIT/PVRIG bispecific antibody, with D3S-001, a KRAS G12C inhibitor, transformed tumor microenvironment from “cold” to “hot” and achieved durable tumor remission in preclinical models

Abstract KRAS G12C inhibitors have demonstrated encouraging clinical benefit in patients with solid tumors harboring KRAS G12C mutation. However, the overall response rate and duration of response remain to be improved. Though combining KRAS G12C inhibitors with anti-PD-1 antibodies showed enhanced preclinical efficacy, clinical benefit for this regimen was compromised by treatment-related toxicities. While the mechanisms underlining these toxicities are being actively investigated, combination strategies incorporating other immunotherapies into KRAS G12C inhibition may provide an alternative to anti-PD-1 combination. We have discovered a new bispecific antibody (BsAb), D3L-002, targeting the TIGIT and PVRIG immune checkpoint molecules that are expressed on activated T and NK cells and mediate inhibitory signaling to counteract the immune stimulatory DNAM-1 pathway. To assess the combination effect of D3L-002 with KRAS G12C inhibitors, the anti-tumor efficacies of KRAS G12C inhibitor D3S-001, a murine surrogate anti-TIGITxPVRIG BsAb (mTxP BsAb), a murine anti-PD-1 antibody (mPD-1 Ab), the combination of D3S-001 with mTxP BsAb and with mPD-1 Ab were evaluated in CT-26 KRAS G12C syngeneic mouse tumor models. Tumor microenvironment (TME) profiling was analyzed by flow cytometry, immunohistology and single cell sequencing. In this study, D3S-001 monotherapy inhibited tumor growth with a 50% complete remission (CR) rate. While mTxP BsAb alone was not effective in this immune “cold” model, combination of D3S-001 with mTxP BsAb resulted in a 70% CR rate, comparable to that of the combination of D3S-001 with the mPD-1 Ab. TME profiling indicated that D3S-001 remodeled the TME from “cold” to “hot” by reducing M2 macrophages and MDSCs while increasing T cells in the tumor. Interestingly, D3S-001 treatment led to increased expression of DNAM-1 on T cells, which has been implicated in augmenting T cell sensitivity towards environmental stimulation. The expression of TIGIT and PD-1 was also upregulated on T cells after D3S-001 treatment, correlating with enhanced T cell activation and anti-tumor efficacy in the combination group of mTxP BsAb and D3S-001 or mPD-1 Ab and D3S-001, respectively. In single cell analysis, mTxP BsAb demonstrated a distinctive effect in regulating immune suppressive Treg population from that of the mPD-1 Ab. While Treg population was increased in D3S-001 or the combination of D3S-001 with mPD-1 Ab group, it was decreased in mTxP BsAb monotherapy or D3S-001 and mTxP BsAb combination group. Collectively, these data showed that D3S-L002’s surrogate mTxP BsAb synergized with D3S-001 in achieving enhanced and durable anti-tumor effect in KRAS G12C-mutant tumors. The combination treatment transformed TME from “cold” to “hot” and inhibited Treg population. These results provide a strong rationale for combining D3L-002 with D3S-001 in clinic trials, which may lead to an alternative treatment option, with differentiated mechanisms and potentially better tolerability, from current strategy in combining anti-PD-1 antibodies with KRAS G12C inhibitors. Citation Format: George Chen, Jing Zhang, Haopeng Rui, Xiaofeng Yang, Tienan Wang. Combination of D3L-002, an anti-TIGIT/PVRIG bispecific antibody, with D3S-001, a KRAS G12C inhibitor, transformed tumor microenvironment from “cold” to “hot” and achieved durable tumor remission in preclinical models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C064.

Spatial multimodal analysis revealed tertiary lymphoid structures as a risk stratification indicator in combined hepatocellular-cholangiocarcinoma

The microenvironment created by tertiary lymphoid structures (TLSs) can support and regulate immune responses, affecting the prognosis and immune treatment of patients. Nevertheless, the actual importance of TLSs for predicting the prognosis of combined hepatocellular-cholangiocarcinoma (cHCC-CCA) patients remains unclear. Herein, using spatial transcriptomic analysis, we revealed that a gene signature of TLSs specific to cHCC-CCA was associated with high-intensity immune infiltration. Then, a novel scoring system was developed to evaluate the distribution and frequency of TLSs in intra-tumoral and extra-tumoral regions (iTLS and eTLS scores) in 146 cHCC-CCA patients. iTLS score was positively associated with promising prognosis, likely due to the decreased frequency of suppressive immune cell like Tregs, and the ratio of CD163+ macrophages to macrophages in intra-tumoral TLSs via imaging mass cytometry, while improved prognosis is not necessarily indicated by a higher eTLS score. Overall, this study highlights the potential of TLSs as a prognostic factor and an indicator of immune therapy in cHCC-CCA.

Temporal changes in regulatory T cell subsets defined by the transcription factor Helios in stroke and their potential role in stroke-associated infection: a prospective case–control study

BackgroundRegulatory T cells (Tregs) are involved in the systemic immune response after ischemic stroke. However, their role remains unclear, and the effect appears to be both neuroprotective and detrimental. Treg suppressor function may result in immunodepression and promote stroke-associated infection (SAI). Thus we assume that the bidirectional effects of Tregs may be in part attributed to the intracellular transcription factor Helios. Tregs with Helios expression (H+ Tregs) constitute 70–90% of all Treg cells and more frequently than Helios-negative Tregs (H− Tregs) express molecules recognized as markers of Tregs with suppressor abilities.Methods and resultsWe prospectively assessed the circulating Treg population with flow cytometry in 52 subjects on days 1, 3, 10 and 90 after ischemic stroke and we compared the results with those obtained in concurrent age-, sex- and vascular risk factor-matched controls. At all studied time points the percentage of H+ Tregs decreased in stroke subjects—D1: 69.1% p < 0.0001; D3: 62.5% (49.6–76.6), p < 0.0001; D10: 60.9% (56.5–72.9), p < 0.0001; D90: 79.2% (50.2–91.7), p = 0.014 vs. controls: 92.7% (81.9–97.0) and the percentage of H− Tregs increased accordingly. In patients with SAI the percentage of pro-suppressor H+ Tregs on post-stroke day 3 was higher than in those without infection (p = 0.03). After adjustment for confounders, the percentage of H+ Tregs on day 3 independently correlated with SAI [OR 1.29; CI 95%: 1.08–1.27); p = 0.02]. Although the percentage of H+ Tregs on day 3 correlated positively with NIHSS score on day 90 (rS = 0.62; p < 0.01) and the infarct volume at day 90 (rS = 0.58; p < 0.05), in regression analysis it was not an independent risk factor.ConclusionsOn the first day after stroke the proportion of H+ vs. H− Tregs changes in favor of pro-inflammatory H− Tregs, and this shift continues toward normalization when assessed on day 90. A higher percentage of pro-suppressive H+ Tregs on day 3 independently correlates with SAI and is associated positively with NIHSS score, but it does not independently affect the outcome and stroke area in the convalescent phase of stroke.