Activation Of Myeloid Cells Research Articles

Payload-delivering engineered γδ T cells display enhanced cytotoxicity, persistence, and efficacy in preclinical models of osteosarcoma.

T cell-based cancer immunotherapy has typically relied on membrane-bound cytotoxicity enhancers such as chimeric antigen receptors expressed in autologous αβ T cells. These approaches are limited by tonic signaling of synthetic constructs and costs associated with manufacturing. γδ T cells are an emerging alternative for cellular therapy, having innate antitumor activity, potent antibody-dependent cellular cytotoxicity, and minimal alloreactivity. We present an immunotherapeutic platform technology built around the innate properties of the Vγ9Vδ2 T cell, harnessing specific characteristics of this cell type and offering an allocompatible cellular therapy that recruits bystander immunity. We engineered γδ T cells to secrete synthetic tumor-targeting opsonins in the form of an scFv-Fc fusion protein and a mitogenic IL-15Rα-IL-15 fusion protein (stIL15). Using GD2 as a model antigen, we show that GD2-specific opsonin-secreting Vγ9Vδ2 T cells (stIL15-OPS-γδ T cells) have enhanced cytotoxicity and promote bystander activity of other lymphoid and myeloid cells. Secretion of stIL-15 abrogated the need for exogenous cytokine supplementation and further mediated activation of bystander natural killer cells. Compared with unmodified γδ T cells, stIL15-OPS-γδ T cells exhibited superior in vivo control of subcutaneous tumors and persistence in the blood. Moreover, stIL15-OPS-γδ T cells were efficacious against patient-derived osteosarcomas in animal models and in vitro, where efficacy could be boosted with the addition of zoledronic acid. Together, the data identify stIL15-OPS-γδ T cells as a candidate allogeneic cell therapy platform combining direct cytolysis with bystander activation to promote tumor control.

Platelet microparticles influence gene expression and modulate biological activities of chronic myeloid leukemia cells (K562).

The current understanding emphasizes the intricate interplay between the Leukemic cell and its environment. Platelet-derived microparticles play a crucial role in facilitating intercellular communication and contribute to the complex landscape of cancer pathology. This study aimed to investigate the influence of platelet-derived microparticles on cell proliferation, apoptosis, and the expression of key genes, including P53, P21, Cyclin D1, Bax, and Bcl-2, within the context of a chronic myeloid leukemia cell line (K562). Platelet-derived microparticles were obtained through centrifugation at various speeds, and their concentration was quantified using the BCA assay. To determine the size and immunophenotypic characteristics of the PMPs, both the DLS technique and flow cytometry were employed. Cell proliferation was assessed using the MTT assay and hemocytometer, and cell cycle analysis was conducted through DNA content evaluation. Real-time PCR was utilized for gene expression analysis of Bax, Bcl-2, Cyclin D1, P53, and P21. Flow cytometry was employed to examine cell apoptosis. The findings revealed that platelet-derived microparticles have the ability to decrease proliferation of the K562 cell line, while not exerting an impact on apoptosis and cell cycle progression. Analysis through real-time PCR indicated an upregulation in the gene expression of P53, P21, and Bcl-2, accompanied by a downregulation in Bax and Cyclin D1. This investigation sheds light on the intricate relationship between chronic myeloid leukemia and its microenvironment, particularly the involvement of platelet-derived microparticles. The study underscores the potential of platelet-derived microparticles to influence cell behavior and gene expression, providing a deeper understanding of their role in CML and its therapeutic implications.

Erratum for the Research Article: "TREM2 inhibition triggers antitumor cell activity of myeloid cells in glioblastoma" by Sun et al.

Erratum for the Research Article: "TREM2 inhibition triggers antitumor cell activity of myeloid cells in glioblastoma" by Sun et al.

Myeloid-specific ferritin light chain deletion does not exacerbate sepsis-associated AKI.

Sepsis-associated acute kidney injury (SA-AKI) is a key contributor to the life-threatening sequelae attributed to sepsis. Mechanistically, SA-AKI is a consequence of unabated myeloid cell activation and oxidative stress that induces tubular injury. Iron mediates inflammatory pathways directly and through regulating the expression of myeloid-derived ferritin, an iron storage protein comprising ferritin light (FtL) and ferritin heavy chain (FtH) subunits. Previous work revealed that myeloid FtH deletion leads to a compensatory increase in intracellular and circulating FtL and is associated with amelioration of SA-AKI. We designed this study to test the hypothesis that loss of myeloid FtL and subsequently, circulating FtL will exacerbate the sepsis-induced inflammatory response and worsen SA-AKI. We generated a novel myeloid-specific FtL knockout mouse (FtLLysM-/-) and induced sepsis via cecal ligation and puncture or lipopolysaccharide endotoxemia. As expected, serum ferritin levels were significantly lower in the knockout mice, suggesting that myeloid cells dominantly contribute to circulating ferritin. Interestingly, although sepsis induction led to a marked production of pro- and anti-inflammatory cytokines, there was no statistical difference between the genotypes. There was a similar loss of kidney function, as evidenced by a rise in serum creatinine and cystatin C and renal injury identified by expression of kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin. Finally, RNA sequencing revealed upregulation of pathways for cell cycle arrest and autophagy postsepsis, but no significant differences were observed between genotypes, including in key genes associated with ferroptosis, an iron-mediated form of cell death. The loss of FtL did not impact sepsis-mediated activation of NF-κB or HIF-1a signaling, key inflammatory pathways associated with dysregulated host response. Taken together, while FtL overexpression was shown to be protective against sepsis, the loss of FtL did not influence sepsis pathogenesis.NEW & NOTEWORTHY Hyperferritinemia in sepsis is often associated with a proinflammatory phenotype and poor prognosis. We previously showed the myeloid deletion of FtH results in a compensatory increase in FtL and is associated with reduced circulating cytokines and decreased rates of SA-AKI in animal sepsis models. Here, we show that myeloid deletion of FtL does not impact the severity of SA-AKI following CLP or LPS, suggesting that FtH plays the predominant role in propagating myeloid-induced proinflammatory pathways.

CCR2+ monocytes promote white matter injury and cognitive dysfunction after myocardial infarction

Survivors of myocardial infarction are at increased risk for vascular dementia. Neuroinflammation has been implicated in the pathogenesis of vascular dementia, yet little is known about the cellular and molecular mediators of neuroinflammation after myocardial infarction. Using a mouse model of myocardial infarction coupled with flow cytometric analyses and immunohistochemistry, we discovered increased monocyte abundance in the brain after myocardial infarction, which was associated with increases in brain-resident perivascular macrophages and microglia. Myeloid cell recruitment and activation was also observed in post-mortem brains of humans that died after myocardial infarction. Spatial and single cell transcriptomic profiling of brain-resident myeloid cells after experimental myocardial infarction revealed increased expression of monocyte chemoattractant proteins. In parallel, myocardial infarction increased crosstalk between brain-resident myeloid cells and oligodendrocytes, leading to neuroinflammation, white matter injury, and cognitive dysfunction. Inhibition of monocyte recruitment preserved white matter integrity and cognitive function, linking monocytes to neurodegeneration after myocardial infarction. Together, these preclinical and clinical results demonstrate that monocyte infiltration into the brain after myocardial infarction initiate neuropathological events that lead to vascular dementia.

Abstract PO2-04-08: Translational insights from a phase 1, first-in-human (FIH) clinical trial of the anti-HER2 CAR macrophage CT-0508 in participants with HER2 positive metastatic breast cancer and other HER2 overexpressing solid tumors

Abstract Background: In pre-clinical studies, CAR macrophages (CAR-M) phagocytose tumor cells, activate the tumor microenvironment (TME), recruit T cells, and induce anti-tumor T cell immunity. CT-0508 is a first-in-class CAR-M product comprised of autologous monocyte-derived macrophages expressing an anti-HER2 CAR. In pre-clinical models, anti-HER2 CAR-M was able to control the growth of syngeneic metastatic HER2+ breast cancer. Here we present preliminary clinical results and translational data from Group 1 of the CT-0508 Phase 1 FIH study. Methods: This multi-center, open-label study is evaluating CT-0508’s safety, tolerability, and manufacturing feasibility in 18 participants with advanced solid tumors overexpressing HER2 with progression on prior therapies. Monocytes are isolated from mobilized apheresis products, differentiated into macrophages, and engineered with an anti-HER2 CAR. Group 1 participants (n = 9) receive a fractionated dose on days 1, 3, 5 and Group 2 participants (n = 9) receive the full dose on day 1. CT-0508 is administered without preparative chemotherapy. Serial blood samples and biopsies (baseline and 2 post-treatment) are collected to investigate safety, pharmacokinetics, and mechanism of action. AU565 and 4T1-HER2 cell lines were utilized to model human and murine breast cancer, respectively, in vitro and in vivo. Results: Nine participants (6F/3M) have been treated in Group 1, comprising breast (4), esophageal (2), cholangiocarcinoma, ovarian, and parotid gland cancers, with a median age of 58. Participants had received a median of 3 (range, 2-11) prior lines of therapy; 8 had received prior anti-HER2 therapy. CT-0508 was successfully manufactured and well tolerated with no dose-limiting toxicities. Three related SAEs occurred in 2 participants: grade 1 CRS with hospitalization for monitoring and grade 2 infusion reaction that resolved within 1 hour were reported in one participant. Grade 2 CRS with fever and hypoxia occurred in another participant and resolved within ~ 72 hours. Five additional participants experienced Grade 1-2 CRS and/or infusion reactions with rapid resolution. There were no cases of Grade 3 or 4 CRS. There were no major organ toxicities. Post-infusion cytokines were transiently elevated in most participants enrolled in group 1 and were self-limiting. Four of the 7 participants evaluated had stable disease. CT-0508 was transiently detectable in the blood and was detected in the TME of 8/9 participants. CT-0508 modulated the TME, leading to myeloid cell activation, effector T cell infiltration, activation, and proliferation. TCR sequencing demonstrated newly expanding T cell clones in the blood post-treatment that accumulated within the TME, suggesting expansion of tumor-reactive T cells upon CT-0508 infusion. Data from participants enrolled in Group 1 will be presented. Most of these patients were breast cancer patients with HER2 overexpressing metastatic disease. Conclusions: CT-0508 was feasible to manufacture and had acceptable safety and tolerability. Early correlative data demonstrate trafficking, TME modulation, and induction of anti-tumor T cell immunity in participants with HER2 overexpressing solid tumors including metastatic breast cancer. The study is actively enrolling (NCT04660929). Citation Format: Yara Abdou, Joanne Mortimer, Paula Pohlmann, Melissa Johnson, Richard Maziarz, Jennifer M. Specht, Claire Dees, Naoto Ueno, Yuan Yuan, Mathew Angelos, Saar Gill, Olga Shestova, Jonathon Serody, Saul Priceman, Rehman Qureshi, Poonam Sonawane, Stefano Pierini, Maria Cecilia Oliveira-Nunes, Daniel Cushing, Michael Klichinsky, Thomas Condamine, Ramona Swaby, Kim Reiss. Translational insights from a phase 1, first-in-human (FIH) clinical trial of the anti-HER2 CAR macrophage CT-0508 in participants with HER2 positive metastatic breast cancer and other HER2 overexpressing solid tumors [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 PO2-04-08.

Altered transcriptomic immune responses of maintenance hemodialysis patients to the COVID-19 mRNA vaccine.

End-stage renal disease (ESRD) patients experience immune compromise characterized by complex alterations of both innate and adaptive immunity, and results in higher susceptibility to infection and lower response to vaccination. This immune compromise, coupled with greater risk of exposure to infectious disease at hemodialysis (HD) centers, underscores the need for examination of the immune response to the COVID-19 mRNA-based vaccines. The immune response to the COVID-19 BNT162b2 mRNA vaccine was assessed in 20 HD patients and cohort-matched controls. RNA sequencing of peripheral blood mononuclear cells was performed longitudinally before and after each vaccination dose for a total of six time points per subject. Anti-spike antibody levels were quantified prior to the first vaccination dose (V1D0) and 7 d after the second dose (V2D7) using anti-spike IgG titers and antibody neutralization assays. Anti-spike IgG titers were additionally quantified 6 mo after initial vaccination. Clinical history and lab values in HD patients were obtained to identify predictors of vaccination response. Transcriptomic analyses demonstrated differing time courses of immune responses, with prolonged myeloid cell activity in HD at 1 wk after the first vaccination dose. HD also demonstrated decreased metabolic activity and decreased antigen presentation compared to controls after the second vaccination dose. Anti-spike IgG titers and neutralizing function were substantially elevated in both controls and HD at V2D7, with a small but significant reduction in titers in HD groups (p<0.05). Anti-spike IgG remained elevated above baseline at 6 mo in both subject groups. Anti-spike IgG titers at V2D7 were highly predictive of 6-month titer levels. Transcriptomic biomarkers after the second vaccination dose and clinical biomarkers including ferritin levels were found to be predictive of antibody development. Overall, we demonstrate differing time courses of immune responses to the BTN162b2 mRNA COVID-19 vaccination in maintenance HD subjects comparable to healthy controls and identify transcriptomic and clinical predictors of anti-spike IgG titers in HD. Analyzing vaccination as an in vivo perturbation, our results warrant further characterization of the immune dysregulation of ESRD. F30HD102093, F30HL151182, T32HL144909, R01HL138628. This research has been funded by the University of Illinois at Chicago Center for Clinical and Translational Science (CCTS) award UL1TR002003.

Combining multi-mode thermal therapy with IL-6 and IL-17A neutralization amplifies antitumor immunity to facilitate long-term survival in LLC1-bearing mice

Non-small cell lung cancer (NSCLC) is known for rapid development and chronic inflammation-induced immunosuppression. IL-6 and IL-17A are the essential cytokines that facilitate NSCLC progression and myeloid-derived suppressive cell (MDSC)-mediated evasion. IL-6 or IL-17A targeting, especially IL-6, shown outstanding efficacy in patient NSCLC controlling, but failed to completely eradicate tumor. The local tumor multi-mode thermal therapy developed in our prior research was demonstrated to stimulate systemic and durable tumor-specific immune response thereby promoting long-term tumor-free survival of mice and prolong the progression-free survival of patients, although the therapeutic efficacy was still affected by high-level preoperative MDSCs. To further improve the efficacy, in this study, IL-6 and IL-17A neutralization were combined with multi-mode thermal therapy in mouse LLC1 NSCLC model. Study revealed that combined with single cytokine neutralization only prolonged the survival time while triple combination therapy efficiently improved the survival rate. Additionally, triple combination therapy reduced the accumulation of MDSCs but promoted their maturation with strengthened activation and function of myeloid cells, thereby triggering a Th1-dominant-CD4+ T cell-response and enhancing the malignant cell-killing capacity of immune cells. Our study highlights the extraordinary efficacy of combining multi-mode thermal therapy with IL-6 and IL-17A neutralization, revealing a new strategy for refractory NSCLC patients.Graphical

Abstract 3920: BND-35, a novel anti-ILT3 antibody for remodulation of the tumor microenvironment

Abstract Background: ILT3 (LILRB4) is expressed in various suppressive myeloid cells including tumor associated macrophages (TAM), myeloid derived suppressor cells (MDSCs) and tolerogenic dendritic cells (DCtol). The binding of ILT3 to its ligands induces an immunosuppressive phenotype in myeloid cells, mediates the inhibition of T cells activity and generates an immunosuppressive tumor microenvironment (TME) which supports tumor growth. The inhibition of ILT3 can restore the anti-tumor activity of myeloid cells and T cells, and thus remodulate the TME from immunosuppressive to pro-inflammatory. Here we describe preclinical characterization of BND-35, a humanized IgG4, ILT3 antagonist antibody developed for the treatment of solid tumors. Methods: BND-35 binding to ILT3 was evaluated by flow cytometry, ELISA and surface plasmon resonance. We investigated the ability of BND-35 to block ILT3 interactions with APOE and fibronectin, to enhance the pro inflammatory activity of various myeloid cells and reverse ILT3-mediated immune suppression of T cells by different suppressive myeloid cells using ELISA and in vitro and ex vivo cell-based assays. The anti-tumor activity of BND-35 was also evaluated in vivo in hILT3 transgenic mouse tumor models as well as in tumoroid systems generated from cancer patients. Results: BND-35 binds ILT3, but not other ILT-family receptors, with low nanomolar affinity and blocks its interaction with APOE and fibronectin in a concentration-dependent manner. ILT3 blockade with BND-35 restored the pro-inflammatory activity of FcR-stimulated DCs and THP1 cells inhibited by fibronectin. BND-35 was also shown to restore an M1 phenotype in cancer patients’ derived monocytes differentiated in the presence of autologous tumor cells. In addition, BND-35 restored T cell activity (both, CD4 and CD8 T cells) inhibited by either DCtol, MDSCs or M2 cells as a single agent and in combination with anti PD-1. BND-35 enhanced immune activity in a unique system of patient-derived tumoroids as evidenced by the secretion of pro-inflammatory cytokines. In vivo, blocking ILT3 activity with BND-35 resulted in decreased tumor growth and induced a pro-inflammatory phenotype in tumor resident T cells and myeloid cells populations as a single agent and in combination with anti PD-1. Conclusions: BND-35 is an anti-ILT3 antagonist antibody that was shown to induce potent pro inflammatory activity of myeloid cells and enhance T cells activity inhibited by ILT3 expressing myeloid suppressive cells in multiple in vitro, ex vivo and in vivo models. By doing so, BND-35 can lead to TME remodelling from immunosuppressive to proinflammatory. Safety, tolerability, and anti-tumor activity of BND-35 will be explored in a first-in-human clinical trial in cancer patients with solid tumors. Citation Format: Tsuri Peretz, Yoav Pizem, Liat Iancovici, Ella Peled, Motti Hakim, Sharon Hashmueli, Ilana Mandel, Yair Sapir, Tehila Ben Moshe. BND-35, a novel anti-ILT3 antibody for remodulation of 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 3920.

Abstract 2478: Inhibition of CD39 by AB598 increases extracellular ATP resulting in activation of myeloid cells and T cells to enhance anti-tumor immunity

Abstract Extracellular ATP (eATP) is a potent immunostimulatory signal in the tumor microenvironment (TME), but it is rapidly degraded into AMP and immunosuppressive adenosine. Therefore, ATP metabolism is an attractive anti-tumor target. Several enzymes are involved in the immunosuppressive process used by the TME to convert ATP to AMP and adenosine. Among them, CD39 (gene: ENTPD1), an extracellular ATPase, is a promising target. Analyzing mRNA expression from the TCGA, we show that CD39 is consistently expressed at high levels in comparison to the other extracellular ATP-converting enzymes, ENPP1 and TNAP. We further demonstrate that CD39 has greater enzymatic activity at the slightly acidic physiological pH (pH = 6.8) of the TME than either ENPP1 or TNAP. Flow cytometry profiling of dissociated primary human gastric tumors showed that CD39 was highly expressed on both myeloid and lymphoid cells, including several populations of T cells present in the tumors. This is distinct from findings in healthy primary human PBMCs that show high expression of CD39 on myeloid subsets and relatively few subsets of T cells with high CD39 expression. AB598 is a novel, humanized, Fc-silent anti-CD39 therapeutic antibody that potently binds to CD39 and inhibits its enzymatic activity with sub-nanomolar potency. Treatment of dissociated primary human gastric tumor cells with AB598 resulted in a decrease in the rate of ATP degradation, indicating both the effectiveness of AB598 and the relevance of CD39 as a main contributor to the ATPase activity of the TME. Although eATP is low in healthy tissues, high levels of ATP can be released when cancer cells are treated with immunogenic cell death (ICD)-inducing agents, increasing the eATP in the TME, providing a rationale for the combination of ICD-inducing chemotherapy and AB598. Thus, cancer cells were co-cultured with monocyte-derived dendritic cells (moDCs) and treated with chemotherapy and AB598 to preserve the eATP released by dying cancer cells. The increased expression of CD83 and CD86 on moDCs demonstrated that the combination treatment enhanced the maturation of moDCs, compared to single or no treatment. To further elucidate the anti-tumor effects of the combination treatment, autogenous T cells were introduced into this system. AB598 significantly enhanced T cell activation in the presence of chemotherapy. These data demonstrate that using AB598 results in elevated eATP, which boosts immune cell activation to promote anti-tumor immunity. Citation Format: Ke Jin, Julie Clor, Kaustubh Parashar, Rebecca Fuchs, LC Stetson, Sean Cho, Matthew J. Walters, Ester Fernandez-Salas, Christine E. Bowman. Inhibition of CD39 by AB598 increases extracellular ATP resulting in activation of myeloid cells and T cells to enhance anti-tumor 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 2478.

Abstract 6687: Evaluation of a new co-cultured microbiome ecosystem therapy candidate (MaaT034) for clinical testing as adjuvant/neoadjuvant to immune checkpoint inhibitors in solid tumors

Abstract Background: Increasing evidence suggests that gut microbiome composition modulates tumor response to therapies, including immune checkpoint inhibitors (ICI). Clinical proofs of concept were obtained in pilot studies using healthy or ICI-responder donor-derived fecal matter transplants to modulate the gut microbiome of non-responding cancer patients and improve their response to ICI. These results support the development of Microbiome Ecosystem TherapiesTM (MET) replicating at large industrial scale the effects of ICI-responders gut microbiome. MaaT Pharma, a clinical-stage biotech, has developed a unique, ground-breaking, patented co-culture process (MET-C). MaaT034, the first-in-class co-cultured microbiome product, has been selected for optimizing intestinal homeostasis and to activate immune functions alone and in combination with an ICI treatment. Method: We combined metagenomic analysis, metabolite quantification by LC-MRM/MS, Caco-2/THP-1 leaky gut model, PBMC assay and mixed lymphocyte reaction (MLR) to assess the impact of MaaT034 on gut homeostasis and immune activation. Results: Metagenomic analysis demonstrates that MaaT034 replicates the richness and diversity of native-based microbiome ecosystems. Metabolite quantification also revealed that MaaT034 microbes secrete anti-inflammatory metabolites such as short chain fatty acids and indoles, as well as metabolites associated with ICI response such as secondary biliary acids. Using a Caco-2/THP-1 leaky gut model, we then demonstrate that MaaT034 conditioned medium was able to restore the integrity of a THP-1-induced damaged gut barrier. This was associated with and a reduction of inflammatory signals. We further performed a human PBMC assay to evaluate the impact of MaaT034 on immune cell activation. We observed the secretion of immunostimulatory cytokines associated with myeloid cell activation in response to MaaT034 conditioned medium. Notably, anti-CD3 mediated T-cells activation was further increased in response to MaaT034 conditioned medium as evidenced by increased IFNγ release associated with increased Granzyme B and CD25. Finally, MLR was performed to determine the immunomodulatory potential of MaaT034 through the interaction between T-cells and monocytes-derived dendritic cells (moDC). Interestingly, MaaT034 conditioned medium improved moDC maturation as well as moDC-induced T-cell activation. MaaT034 conditioned medium further increased anti-PD-1 mediated T-cell activation, as evidenced by IFNγ release. Conclusion: Altogether, these results highlight the potential of MaaT034 to produce metabolites involved in the restoration of gut barrier integrity and stimulation of immune cell response to ICI therapy, with potential benefit for solid tumors treatment. Citation Format: Bastien Laperrousaz, Julie Reygner, Cyrielle Gasc, Charlotte Petitjean, Aurore Duquenoy, Lora Martin, Vincent Bonnaud, Marianne Robin, Sophie Declomesnil, Carole Schwintner, Nathalie Corvaïa. Evaluation of a new co-cultured microbiome ecosystem therapy candidate (MaaT034) for clinical testing as adjuvant/neoadjuvant to immune checkpoint inhibitors in solid tumors [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 6687.

Abstract 5562: Altered tumor microenvironment in animal model of concomitant GBM and Alzheimer's pathology

Abstract Glioblastoma (GBM) and Alzheimer’s disease (AD) are two devastating central nervous system diagnoses with no known cure. Both diseases are associated with advanced age. The majority of GBM tumors form in the frontal and temporal lobes, two of the brain regions most impacted by amyloid and tau pathology in AD. Females have a higher risk of AD, while males have a higher risk of GBM. Several large case series have established epidemiological evidence that the two diseases are inversely correlated. Nevertheless, it remains unknown whether presence of subclinical amyloid or tau pathology antagonizes the establishment or progression of GBM. The present study sought to characterize GBM growth, progression, and immune response in the setting of concomitant AD pathology using the syngeneic murine GL261 tumor model. To further understand the tumor cell changes that occur in the presence or absence of AD pathology, we engineered GL261 with a dual-tagged vector consisting of RiboTag (to allow for full-length mRNA profiling) and TurboID (to allow for proteomic profiling). GL261 cells were injected intracranially into APPNL-G-F/NL-G-F - MAPThuman/human, APPNL-G-F/+ - MAPThuman/+, and wildtype C57BL/6J mice. Tumors in both wildtype and AD conditions contained ~50% intratumoral myeloid cells (Iba+, P2RY12-). Differential activation of intratumoral myeloid cells will be assessed with immunohistochemistry. Microgliosis (IBA1, P2RY12) and astrogliosis (GFAP) around the tumor in the setting of Alzheimer’s pathology versus normal conditions will be compared. Invasiveness, proliferation, DNA damage (pH2AX), and apoptosis (cleaved PARP, cleaved Caspase 3) will be compared. Tumor cell-specific changes unique to tumors in the AD microenvironment will be assessed transcriptionally with RiboTag profiling as well as proteomically with TurboID purifications. Our preliminary data suggests that the presence of concomitant AD pathology affects GBM growth and progression as well as the immune response to the tumor, and warrants further investigation. Citation Format: David Nascari, Ryan Eghlimi, Angad Beniwal, Drake Alton, John Fryer, Nhan L. Tran. Altered tumor microenvironment in animal model of concomitant GBM and Alzheimer's pathology [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 5562.

Abstract 7628: Pharmacodynamic biomarkers for Rac and Cdc42 inhibitor efficacy

Abstract Metastatic disease drastically reduces clinical prognosis, and remains the primary cause of mortality from solid cancers, such as breast and pancreatic cancer. Since targeted therapeutic options are limited, we developed small molecule compounds to block activation (GTP loading) of the Rho GTPases Rac and Cdc42. Rac and Cdc42 are ideal molecular targets due to their regulation of cell migration, proliferation, invasion, and signaling in cancer and immunosuppressive cells in the tumor microenvironment. Our lead compound MBQ-167 is a dual Rac and Cdc42 inhibitor with IC50 of ~100 nM for inhibition of Rac/Cdc42 activation and the phosphorylation of their common downstream effector p21-activated kinase (PAK). MBQ-167 is highly effective in mouse models of breast cancer metastasis and is currently undergoing a Phase I clinical trial in advanced breast cancer patients. The purpose of this study is to investigate potential target molecules that can be used as biomarkers predictive of Rac/Cdc42 inhibitor efficacy. We recently published that in addition to inhibiting the growth and migration of breast and pancreatic cancer cells, MBQ-167 inhibits macrophage cell migration, immunosuppressive myeloid cell activation and release of interleukin-6 (IL-6), a pro-inflammatory cytokine associated with cancer. Transcriptomic data of tumors from mice treated with vehicle or MBQ-167 identified a number of immunomodulatory pathways downregulated by MBQ-167, including IL-6 and S100A family signaling, and Chitinase 3-like (CHI3L1/CHI4L1) genes coding for the human YKL-40 protein. We tested for the activation status of PAK (phospho (p)-PAK) as a diagnostic marker for Rac/Cdc42 inhibitor efficacy using breast cancer patient tissue in ex vivo culture treated with vehicle or MBQ-167 and found decreased p-PAK staining following immunohistochemistry of MBQ-167-treated tissue. From flow cytometry, using Alexa-488-tagged anti p-PAK antibody, we found that p-PAK was reduced from peripheral blood mononuclear cells (PBMCs) following MBQ-167. ELISA assays for YKL-40/CHI3L1 proteins after treatment of pancreatic cancer cell lines and macrophage-like cells with Rac/Cdc42 inhibitors show that MBQ-167 and the derivative MBQ-168 reduced CHI3L1 levels from conditioned media. These results demonstrate the potential of p-PAK and YKL-40/CHI3L1 from blood as biomarkers for Rac/Cdc42 inhibitor efficacy. This study impacts pharmacodynamic biomarker design for the planned Phase 2 clinical trials for MBQ-167 in breast and pancreatic cancer. Citation Format: Anamaris Torres-Sanchez, Ailed M. Cruz-Collazo, Michael Rivera-Robles, Olga Katsara, Stephanie Dorta-Estremera, Viviana Negron, Victor P. Carlo, Robert J. Schneider, Suranganie Dharmawardhane. Pharmacodynamic biomarkers for Rac and Cdc42 inhibitor efficacy [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 7628.

Abstract 1364: Characterization of CHS-1000, an Fc-modified anti-ILT4 monoclonal antibody for reprogramming suppressive myeloid cells in solid tumors

Abstract Tumor resident immunosuppressive myeloid cells play a significant role in inducing resistance to cancer immunotherapy and are associated with poor prognosis in several solid tumors. The leukocyte immunoglobulin-like receptor B2 (LILRB2), also known as ILT4, is primarily expressed on myeloid cells and is a negative regulator of myeloid cell activation. ILT4 and its primary ligands (HLA-G, HLA-A) are widely expressed in various solid tumors and are associated with disease progression, tumor metastasis and poor clinical outcome. Abrogating inhibitory signals mediated through ILT4 and its ligands is a promising strategy to reprogram suppressive myeloid cells and enhance efficacy of immune checkpoint therapies. Here we report IND-enabling preclinical characterization of CHS-1000, a novel recombinant humanized Fc-modified IgG1 antibody with attenuated Fc-gamma receptor (FcγR) binding, that specifically targets immunoglobulin-like transcript 4 (ILT4). CHS-1000 selectively binds to human ILT4 with high affinity and potently blocks ILT4 interactions with its primary ligands (HLA-A, HLA-G). Functionally, CHS-1000 promotes re-polarization of suppressive myeloid cells to a pro-inflammatory phenotype and enhances activation of dendritic cells and T cells. Combinations of CHS-1000 with PD-1 inhibitors or other immunotherapy agents hold particular promise for enhanced anti-tumor activity. These preclinical characterization data support clinical development of CHS-1000 in combination with toripalimab (a commercial stage anti-PD-1 antibody) as an immunotherapy treatment for patients with solid tumors. Citation Format: Narendiran Rajasekaran, Xiaoguang Wang, Scott Klakamp, Sruthi Ravindranathan, Suzanna Tatarewicz, Julia Du, Brian Nguyen, Kate Widmann, Nessa Hawkins, Daniel J. Chin, Theresa LaVallee, Varun Kapoor. Characterization of CHS-1000, an Fc-modified anti-ILT4 monoclonal antibody for reprogramming suppressive myeloid cells in solid tumors [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 1364.

Abstract 2377: HER2-ADC efficacy is rooted in its induction of immunogenic cell death with FcGR activation and a systemic bystander effect

Abstract Background: T-DXd is an antibody-drug conjugate (ADC) targeting HER2 that has demonstrated superior clinical efficacy over previous HER2-targeting agent Trastuzumab emtansine (T-DM1). Notably, T-Dxd is clinically effective in breast cancers (BC) with a range of HER2 expression. While its purported mechanism of action (MOA) involves its cleavable linker leading to bystander killing, it remains unclear how this potential MOA accounts for efficacy in HER2-low cancers or the role FCGR-mediated signaling and immune induction plays in its clinical efficacy. Method: In vitro studies utilized co-culture, internalization, FCGR activation, ADCP, flow cytometry, and gene expression by QRT-PCR and ELISA assays. Assessments of tumor antigen-specific T cell stimulation involved JEDI T cells. In vivo studies were conducted using in vivo implantation of HER2+ and HER2- cells, PK assessments of T-Dxd/DM1 and therapeutic effects determined using an endogenous HER2 transgenic mouse model that measured HER2-specific adaptive immune responses, in combination with immune checkpoint blockade anti-CD47. Results: T-Dxd elicited a systemic bystander effect that was only partially dependent on HER2 expression, mediated by specific cathepsins in the extracellular TME. Notably, T-Dxd cytotoxicity induced immunogenic cell death (ICD), while also retaining the ability to engage FCGRs to promote ADCP and innate immune activation. ICD was mediated by secretion of specific Dxd driven DAMPs (HMGB1 and eATP), resulting in TLR4/STING activation. ICD and FCGR activation along with antigen ADCP together elicited myeloid cell activation (CD80, CD40) and antigen presentation, resulting in effective expansion of tumor antigen-specific T cells responses, demonstrated by co-culture assays using EGFP/HER2+ BC cells and CD8+ JEDI T cells. T cell activation required TLR4 and STING pathways while in vivo, T-Dxd anti-tumor responses associated with augmented HER2-specific T and B cell responses. However, T-Dxd also induced CD47 to limit phagocytosis. But, the use of CD47/SIRPa blocking antibodies dramatically enhanced CD8+ T cell expansion in vitro and anti-tumor efficacy in vivo upon T-Dxd treatment. Conclusion: Our study demonstrates that T-Dxd is cleavable in HER2 negative BC in vivo, which permits more widespread Dxd activity against HER2 low BC. Critically, Dxd elicits ICD, resulting in innate immune stimulation of myeloid cells, which when combined with FCGR activation and ADCP, leads to a striking induction of tumor-specific adaptive immunity. This combination was unique to T-Dxd, which may underlie its clinical superior efficacy. However, T-Dxd activity also elicits suppressive CD47 expression which could be negated using CD47/SIRPA blockade. We found that this combination dramatically enhanced T-Dxd resulted therapeutic efficacy, thus supporting clinical exploration of these combinations. Citation Format: Li-Chung Tsao, Xingru Ma, John S. Wang, Timothy N. Trotter, Tao Wang, Jun-Ping Wei, Gang-jun Lei, Jason McBane, Ping Fan, Ivan Spasojevic, Zachary C. Hartman. HER2-ADC efficacy is rooted in its induction of immunogenic cell death with FcGR activation and a systemic bystander effect [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 2377.

Abstract 3641: Pharmacodynamic and predictive biomarker results from the phase I dose escalation study of NGM707, an ILT2/ILT4 dual antagonist antibody, in patients with advanced solid tumors

Abstract Background: NGM707 is a dual antagonist antibody that binds a shared epitope of the immune inhibitory receptors ILT2 (LILRB1) and ILT4 (LILRB2). In preclinical studies, NGM707 reprogrammed suppressive myeloid cells via blockade of ILT2/ILT4 and enhanced NK and CD8+ T cell activity via blockade of ILT2; furthermore, NGM707 and pembrolizumab acted additively in vitro to enhance CD4+ T cell activation in mixed lymphocyte reactions. NGM707-IO-101 (NCT04913337) is a first-in-human Phase 1/2 clinical trial of NGM707 monotherapy and combination with pembrolizumab. Here we report pharmacodynamic and predictive biomarker data from NGM707-IO-101 monotherapy and combination dose escalation cohorts. Methods: Eligible patients with advanced or metastatic solid tumors were enrolled into escalating dose cohorts from 6 to 1800 mg NGM707, alone or in combination with 200 mg pembrolizumab, administered Q3W iv. Biomarker assessments of tumors comprised RNA-sequencing and immunohistochemistry (including ILT2, ILT4, CD163) of archival/baseline (N= 41 IHC, 47 RNA) and paired on-treatment tumor biopsies (N=13 IHC, 21 RNA). Peripheral blood biomarker samples were collected on days 1, 4, 8, and 15 of cycle 1 and prior to dosing at each subsequent cycle. Blood biomarker assessments included circulating cytokines/chemokines, PBMC RNA-sequencing, and flow cytometry immunophenotyping. Baseline biomarkers were associated with anti-tumor activity per RECIST v1.1. Results: Pre-treatment biopsies from patients with disease control (DC) showed higher expression of genes in the 18-gene tumor inflammation signature (TIS) than patients with progressive disease (PD). A composite gene signature incorporating gene sets related to TIS, NK cell activity, and tumor cell proliferation had a statistically stronger association with DC than TIS genes alone. Baseline ILT2/ILT4 target expression (≥1% of tumor area) was observed in 31 (75.6%) patients, with similar levels observed in patients with DC and PD. Pharmacodynamic changes were observed in tumor samples following treatment, including increased expression of gene signatures that reflect myeloid cell activation and a proinflammatory tumor microenvironment. Decreased protein expression of the immunosuppressive myeloid marker CD163 was observed following treatment in both blood and tumor for a subset of patients. Proinflammatory chemokines including CXCL9 increased in serum following treatment. Conclusion: Baseline gene expression signatures have shown an encouraging association with clinical benefit from NGM707 and merit further investigation as promising predictive biomarkers. Protein and gene expression changes reflecting the expected modes of action of NGM707 and pembrolizumab were observed in both peripheral blood and tumor biopsies following treatment. Citation Format: Lisa K. Blum, Hung-I H. Chen, Anushka De Costa, Anjushree Iyer, Geoffrey W. Stone, Nicole D. Galicia, Jerry Chan, Brenda Dampier, Katherine Wu, Ursula Jeffry, Kefei Zhou, Joanne Sloan-Lancaster, Dhiraj Abhayankar, Vladimir Hanes, Hsiao D. Lieu, Daniel D. Kaplan, Julie M. Roda. Pharmacodynamic and predictive biomarker results from the phase I dose escalation study of NGM707, an ILT2/ILT4 dual antagonist antibody, in patients with advanced solid tumors [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 3641.

SOCS3 regulates pathological retinal angiogenesis through modulating SPP1 expression in microglia and macrophages

Pathological ocular angiogenesis has long been associated with myeloid cell activation. However, the precise cellular and molecular mechanisms governing the intricate crosstalk between the immune system and vascular changes during ocular neovascularization formation remain elusive. In this study, we demonstrated that the absence of the suppressor of cytokine signaling 3 (SOCS3) in myeloid cells led to a substantial accumulation of microglia and macrophage subsets during the neovascularization process. Our single-cell RNA sequencing data analysis revealed a remarkable increase in the expression of the secreted phosphoprotein 1 (Spp1) gene within these microglia and macrophages, identifying subsets of Spp1-expressing microglia and macrophages during neovascularization formation in angiogenesis mouse models. Notably, the number of Spp1-expressing microglia and macrophages exhibited further elevation during neovascularization in mice lacking myeloid SOCS3. Moreover, our investigation unveiled the Spp1 gene as a direct transcriptional target gene of signal transducer and activator of transcription 3. Importantly, pharmaceutical activation of SOCS3 or blocking of SPP1 resulted in a significant reduction in pathological neovascularization. In conclusion, our study highlights the pivotal role of the SOCS3/STAT3/SPP1 axis in the regulation of pathological retinal angiogenesis.

B cell depletion with anti-CD20 promotes neuroprotection in a BAFF-dependent manner in mice and humans.

Anti-CD20 therapy to deplete B cells is highly efficacious in preventing new white matter lesions in patients with relapsing-remitting multiple sclerosis (RRMS), but its protective capacity against gray matter injury and axonal damage is unclear. In a passive experimental autoimmune encephalomyelitis (EAE) model whereby TH17 cells promote brain leptomeningeal immune cell aggregates, we found that anti-CD20 treatment effectively spared myelin content and prevented myeloid cell activation, oxidative damage, and mitochondrial stress in the subpial gray matter. Anti-CD20 treatment increased B cell survival factor (BAFF) in the serum, cerebrospinal fluid, and leptomeninges of mice with EAE. Although anti-CD20 prevented gray matter demyelination, axonal loss, and neuronal atrophy, co-treatment with anti-BAFF abrogated these benefits. Consistent with the murine studies, we observed that elevated BAFF concentrations after anti-CD20 treatment in patients with RRMS were associated with better clinical outcomes. Moreover, BAFF promoted survival of human neurons in vitro. Together, our data demonstrate that BAFF exerts beneficial functions in MS and EAE in the context of anti-CD20 treatment.

Abstract B086: Novel myeloid activation therapy promotes regression of metastatic ovarian cancer

Abstract Significance: Most ovarian cancer (OC) patients ultimately succumb to drug-resistant intraperitoneal metastases. There is an unmet need to develop novel therapies against metastatic OC. Whether activating myeloid cells can promote OC regression has not been explored extensively. The purpose of this study is to develop a novel immunotherapy that activates myeloid cells with the goal of eradicating metastatic OC. Methods: In this study, we mainly relied on syngeneic mouse models of metastatic OC. To model metastatic OC in mice, we performed intraperitoneal injection of clinically relevant murine OC cell lines that were recently established by Dr. Robert Weinberg’s group, including homologous recombination (HR)-proficient KPCA cells (KRASG12VTrp53R172HCcne1OEAkt2OE ) and HR-deficient BPPNM cells (Brca1−/−Trp53R172HPten−/− Nf1−/−MycOE ). To activate myeloid cells, we used b-glucan and interferon (IFN) γ. b-glucan is a yeast cell wall polysaccharide that is currently in clinical trials to treat multiple cancers (NCT05159778). It canonically activates myeloid cells through the Dectin-1-spleen tyrosine kinase (SYK) pathway and induces infiltration of monocytes and neutrophils. IFNγ activates macrophages to an anti-tumor status. We investigated whether and how b-glucan affects metastatic OC with or without IFNγ using bioluminescence imaging, confocal imaging, flow cytometry, and single-cell RNA sequencing (scRNA seq). Finally, we tested whether combining myeloid cell activation with carboplatin could eradicate metastatic OC.Results: First, we found that b-glucan alone was highly efficient in clearing ascites. b-glucan captured free-floating OC cells into solid nodules within 5 hours after its injection through two non-redundant and equally important pathways: (1) an unexpected Dectin-1-SYK-independent, heparin-sensitive pathway that was mediated by resident macrophages in the peritoneal fluid; (2) a Dectin-1-SYK-PAD4-dependent pathway that was mediated by neutrophil extracellular traps in the omentum. Second, we found that combining b-glucan with IFNγ (b-glucan/IFNγ) not only cleared ascites but also reduced total metastases compared to PBS-, b-glucan-, or IFNγ-treated mice. This anti-tumor immunity required T cells and non-tumor IFNγ signaling in the host. Third, using scRNA seq, we found that b-glucan/IFNγ induced the enrichment of unique subsets of tumoricidal neutrophils and macrophages compared to other groups. Interestingly, the novel macrophage subset selectively expressed an interleukin (IL)-12 family cytokine, IL-27. We found that blocking IL-27 significantly impaired the anti-tumor response. Finally, combining b-glucan/IFNγ with carboplatin nearly eradicated chemoresistant KPCA tumors and chemosensitive BPPNM tumors. Patients with high expression of the genes identified in the novel myeloid cell subsets correlate with better overall survival. Conclusion: We have identified a novel combination therapy of myeloid activation and chemotherapy that could potentially transform treatments against metastatic OC. Citation Format: Brennah Murphy, Taito Miyamoto, Bryan Manning, Toshitha Kannan, Anastasia Ghilkovsky, Yulia Nefedova, Daniel Claiborne, Rugang Zhang, Andrew Kossenkov, Nan Zhang. Novel myeloid activation therapy promotes regression of metastatic ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B086.

ILT4 facilitates angiogenesis in non-small cell lung cancer.

Antiangiogenic therapy targeting VEGF-A has become the standard of first-line therapy for non-small cell lung cancer (NSCLC). However, its clinical response rate is still less than 50%, and most patients eventually develop resistance, even when using combination therapy with chemotherapy. The major cause of resistance is the activation of complex bypass signals that induce angiogenesis and tumor progression. Therefore, exploring novel proangiogenic mechanisms and developing promising targets for combination therapy are crucial for improving the efficacy of antiangiogenic therapy. Immunoglobulin-like transcript (ILT) 4 is a classic immunosuppressive molecule that inhibits myeloid cell activation. Recent studies have shown that tumor cell-derived ILT4 drives tumor progression via the induction of malignant biologies and creation of an immunosuppressive microenvironment. However, whether and how ILT4 participates in NSCLC angiogenesis remain elusive. Herein, we found that enriched ILT4 in NSCLC is positively correlated with high microvessel density, advanced disease, and poor overall survival. Tumor cell-derived ILT4 induced angiogenesis both invitro and invivo and tumor progression and metastasis invivo. Mechanistically, ILT4 was upregulated by its ligand angiopoietin-like protein 2 (ANGPTL2). Their interaction subsequently activated the ERK1/2 signaling pathway to increase the secretion of the proangiogenic factors VEGF-A and MMP-9, which are responsible for NSCLC angiogenesis. Our study explored a novel mechanism for ILT4-induced tumor progression and provided a potential target for antiangiogenic therapy in NSCLC.