Journal Articles

Loss of the autoimmune risk gene TREX1 reveals a convergence of mechanisms promoting immune tolerance loss and antitumor immunity

As certain irAEs correlate with clinical efficacy following checkpoint inhibitor therapy, Lim and Williams et al. investigated the relationship between autoimmunity and antitumor immunity. Loss of TREX1, an autoimmune risk gene and key negative regulator of the STING and type I IFN pathways promoted antitumor immunity in mice, and shared pathways with successful cancer immunotherapy. Like in PDCD1-/- and CTLA4-/- mice, constitutive TREX1 loss resulted in multiorgan CD8+ T cell influx, autoimmunity, and myocarditis. Conditional systemic TREX1 ablation was well tolerated and promoted effective CD8+ T cell-driven antitumor immunity, suggesting a new opportunity for immunotherapy.

Contributed by Katherine Turner

As certain irAEs correlate with clinical efficacy following checkpoint inhibitor therapy, Lim and Williams et al. investigated the relationship between autoimmunity and antitumor immunity. Loss of TREX1, an autoimmune risk gene and key negative regulator of the STING and type I IFN pathways promoted antitumor immunity in mice, and shared pathways with successful cancer immunotherapy. Like in PDCD1-/- and CTLA4-/- mice, constitutive TREX1 loss resulted in multiorgan CD8+ T cell influx, autoimmunity, and myocarditis. Conditional systemic TREX1 ablation was well tolerated and promoted effective CD8+ T cell-driven antitumor immunity, suggesting a new opportunity for immunotherapy.

Contributed by Katherine Turner

ABSTRACT: Checkpoint inhibitors targeting PD-1 and CTLA-4 have transformed cancer therapy. Both are genetically associated with autoimmune disorders. Moreover, certain immune-related adverse events and autoimmune risk variants are linked to the clinical efficacy of checkpoint inhibition. These associations suggest common principles governing successful cancer immunotherapy and autoimmune susceptibility. Here, we show that ablation of the cytosolic DNA exonuclease TREX1 predisposes mice to autoimmunity while promoting robust antitumor immunity. Constitutive TREX1 loss leads to early onset autoimmunity, characterized by multiorgan CD8+ T cell infiltration, myocarditis, and Sjgren's syndrome-like disease. In contrast, induced systemic TREX1 ablation is well tolerated and promotes effective CD8+ T cell-driven antitumor immunity. Detailed phenotypic studies revealed a notable overlap between productive antitumor and pathogenic autoimmune CD8+ T cell responses. Collectively, we provide mechanistic evidence for interrelated mechanisms underlying autoimmunity and successful cancer immunotherapy, uncover key parallels between adaptive T cell and innate immune checkpoints, and suggest that targeting autoimmune risk genes represents a promising future avenue for cancer immunotherapy.

Author Info: 1Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.

Author Info: 1Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.

Tumors hijack immune-privileging regulons via distinct cell types to confer T cell desertion and immunotherapy resistance across various cancers

Lawal et al. identified an immune-privileging regulon signature (IMPREG) from tumor samples of patients who were non-responsive to ICB. IMPREG mirrors transcriptional programs of immune-privileged organs. Transcriptomics revealed that IMPREG was activated via three compartments: immature neuronal-like malignant cells, myofibroblastic CAFs, or endothelial cells, forming niches devoid of effector T cells and enriched for TGFβ3, CXCL12, and IL-34-driven suppressive circuits. High IMPREG scores predicted ICB resistance in 14 cancer types, and was associated with increased sensitivity to EGFR inhibitors and anti-angiogenic therapies.

Contributed by Shishir Pant

Lawal et al. identified an immune-privileging regulon signature (IMPREG) from tumor samples of patients who were non-responsive to ICB. IMPREG mirrors transcriptional programs of immune-privileged organs. Transcriptomics revealed that IMPREG was activated via three compartments: immature neuronal-like malignant cells, myofibroblastic CAFs, or endothelial cells, forming niches devoid of effector T cells and enriched for TGFβ3, CXCL12, and IL-34-driven suppressive circuits. High IMPREG scores predicted ICB resistance in 14 cancer types, and was associated with increased sensitivity to EGFR inhibitors and anti-angiogenic therapies.

Contributed by Shishir Pant

ABSTRACT: Immune checkpoint blockade (ICB) has transformed oncology, yet most patients fail to respond, suffer from hyper-progressive disease, or face severe immune-related toxicities, underscoring the urgent need for biomarkers that identify non-responders. Here we show that tumors co-opt an immune-privileging regulon signature (IMPREG) mirroring transcriptional programs of immune-privileged organs - to enforce T-cell desertion and ICB resistance across solid tumor types. Single-cell and spatial transcriptomic analyses reveal that tumors activate IMPREG through three distinct cellular routes: malignant cells adopting immature neuronal states, cancer-associated fibroblasts assuming myofibroblast identities, or endothelial cells - each creating localized niches of immune suppression and antigen-presentation collapse. Across 4 discovery and 36 validation clinical datasets, IMPREG consistently predicts immunotherapy resistance in 14 distinct cancer types, functioning as an orthogonal marker independent of established biomarkers. Crucially, IMPREG-expressing tumors show enhanced sensitivity to EGFR inhibitors or anti-angiogenic therapies in specific tumor entities. These findings suggest IMPREG as a dual-utility predictive biomarker for personalized treatment stratification.

Author Info: 1UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA. 2Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA. 3Magee-Womens Hospital of UPMC,

Author Info: 1UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA. 2Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA. 3Magee-Womens Hospital of UPMC, Pittsburgh, PA, USA. 4UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA. xiaosongw@pitt.edu. 5Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA. xiaosongw@pitt.edu.

CD39+CD49a+CD103+ cytotoxic tissue-resident natural killer cells infiltrate and control solid epithelial tumor growth in mice

Two recent papers phenotyped tumoral NK cell subsets. Lozada et al. detected a tissue-resident (TR) adaptive subset that was IFNG-driven, associated with better clinical outcomes and response to checkpoint blockade, while canonical NK cells expressed high TGFB1 and were suppressive. Horowitz, Mahammad, Ho Shin et al. also found that tissue-resident CD49a+CD103+ NK cells (trNK cells) can have suppressive or cytotoxic functions. A cytotoxic trNK population expressing CD39 had the highest cytolytic antitumor activity and could be differentiated and expanded ex vivo for adoptive transfer.

Two recent papers phenotyped tumoral NK cell subsets. Lozada et al. detected a tissue-resident (TR) adaptive subset that was IFNG-driven, associated with better clinical outcomes and response to checkpoint blockade, while canonical NK cells expressed high TGFB1 and were suppressive. Horowitz, Mahammad, Ho Shin et al. also found that tissue-resident CD49a+CD103+ NK cells (trNK cells) can have suppressive or cytotoxic functions. A cytotoxic trNK population expressing CD39 had the highest cytolytic antitumor activity and could be differentiated and expanded ex vivo for adoptive transfer.

ABSTRACT: Human tissue-resident natural killer (NK) cells (trNK cells), broadly defined by markers of tissue residency, such as CD49a [integrin α1 (ITGA1)] and CD103 [integrin αE (ITGAE)], are increasingly recognized for their immunoregulatory role in host control of infection, malignancy, and autoimmunity. Although the importance of transforming growth factor-β in trNK cell differentiation has been demonstrated, the context in which the differentiation of CD49a+CD103+ trNK cells occurs can result in either an immunosuppressive phenotype (e.g., decidual NK cells) or a highly cytotoxic one (e.g., some tumor trNK subsets). To understand this dichotomy better, we used a multiomic approach to molecularly characterize these cells. We identified a cytotoxic trNK (ctrNK) cell population, characterized by the expression of CD39. These ctrNK cells exhibited superior cytolytic activity against tumor target cells, enhanced capacity to infiltrate into solid tumor microenvironments, and augmented ability to control solid tumor growth in vivo compared with conventionally activated peripheral NK cells. This heightened cytolytic and infiltrative functionality of ctrNK cells appeared to be conferred, in part, by the expression of CD103 and by avidity for tumor targets. Because adoptive immune cell therapy of solid tumor malignancies has been challenged by the inefficiency of ex vivo expanded immune cells to infiltrate immunosuppressive solid tumor microenvironments, our observations that ctrNK cells can be differentiated and expanded ex vivo present a potential platform for adoptive cell therapy of solid tumor malignancies.

Author Info: 1Department of Otolaryngology-Head & Neck Surgery, Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA. 2Department of Bioengineering, Stanfo

Author Info: 1Department of Otolaryngology-Head & Neck Surgery, Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA 94305, USA. 2Department of Bioengineering, Stanford University, Stanford, CA 94305, USA. 3Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA. 4Department of Pathology, Stanford University School of Medicine, Stanford, CA 94305, USA. 5Pelotonia Institute for Immuno-Oncology, Ohio State University Comprehensive Cancer Center-the James, Columbus, OH 43210, USA. 6Department of Molecular Medicine and Therapeutics, College of Medicine, Ohio State University, Columbus, OH 43210, USA. 7Department of Biochemistry, Stanford University, Stanford, CA 94305, USA. 8Division of Infectious Diseases, Department of Medicine, Stanford University School of Medicine, Stanford, CA 94305, USA. 9Section of Computational Biology, Division of Oncology, Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110, USA. 10Siteman Cancer Center at WashU Medicine, St. Louis, MO 63110, USA.

Integrated Single-Cell Profiling Reveals Dichotomous NK Cell Populations Associated with Immunosuppression in Solid Tumors

Two recent papers phenotyped tumoral NK cell subsets. Lozada et al. detected a tissue-resident (TR) adaptive subset that was IFNG-driven, associated with better clinical outcomes and response to checkpoint blockade, while canonical NK cells expressed high TGFB1 and were suppressive. Horowitz, Mahammad, Ho Shin et al. also found that tissue-resident CD49a+CD103+ NK cells (trNK cells) can have suppressive or cytotoxic functions. A cytotoxic trNK population expressing CD39 had the highest cytolytic antitumor activity and could be differentiated and expanded ex vivo for adoptive transfer.

Two recent papers phenotyped tumoral NK cell subsets. Lozada et al. detected a tissue-resident (TR) adaptive subset that was IFNG-driven, associated with better clinical outcomes and response to checkpoint blockade, while canonical NK cells expressed high TGFB1 and were suppressive. Horowitz, Mahammad, Ho Shin et al. also found that tissue-resident CD49a+CD103+ NK cells (trNK cells) can have suppressive or cytotoxic functions. A cytotoxic trNK population expressing CD39 had the highest cytolytic antitumor activity and could be differentiated and expanded ex vivo for adoptive transfer.

ABSTRACT: Natural killer (NK) cells represent key effectors of antitumor immunity, yet emerging evidence highlights populations with distinct roles in cancer. Despite such expanded diversity within the NK cell repertoire, we lack an understanding of how this heterogeneity impacts immune responses and downstream clinical outcomes. Using single-cell RNA-sequencing (scRNA-seq), we systematically profiled NK cells across cancer and uncovered a dichotomous phenotypic and functional landscape of tumor-infiltrating NK cells shaped by opposing intrinsic signaling programs that drive the expression of IFNG or TGFB1. These divergent programs are associated with distinct transcription factor circuits that integrate cues within the tumor microenvironment and skew NK cells towards pro-inflammatory or suppressive functions. We found that the capacity for NK cells to engage in either functional direction is intrinsically linked to their phenotypic identity. Canonical NK cells recruited from circulation predominantly directed suppressive TGFB1 signals towards effector CD8+ T cells in tumors. Of note, these subsets exhibited higher TGFB1 expression than intratumoral myeloid cells across tumor types. In contrast, a tissue-resident adaptive subset exhibited exclusively pro-inflammatory IFNG-driven profiles and was associated with prolonged survival in both primary and metastatic tumor settings. Moreover, these tissue-resident adaptive NK cells, but not other subsets, were linked to response to immune checkpoint blockade. Collectively, our study reveals a previously unrecognized regulatory axis in NK cells that shapes NK cell diversity and augments broader antitumor immune responses.

Author Info: 1University of Minnesota Minneapolis United States. 2Caris Life Sciences (United States) Irving, Texas United States. 3University of Minnesota Cancer Center Minneapolis United Stat

Author Info: 1University of Minnesota Minneapolis United States. 2Caris Life Sciences (United States) Irving, Texas United States. 3University of Minnesota Cancer Center Minneapolis United States. 4Caris Life Sciences (United States) Phoenix, AZ United States. 5University of Minnesota Minnesota, MN United States. 6University of Minnesota Minneapolis, Minnesota United States. 7Mayo Clinic Rochester, MN United States. 8University of Chicago Chicago, IL United States. 9Caris Life Sciences (United States) Los Angeles, CA United States. 10University of Minnesota Minneapolis, MN United States.

Polymer-mRNA complexes for monocyte-trafficked, lymph node-targeted cancer vaccination

To improve mRNA vaccine delivery to lymph nodes, Ren, Zhao, and Zhou et al. developed a DTC-modified, PEI-based, transferrin receptor-associating polyplex (TRAP) that enters cells by binding to TfR1, which is highly expressed on monocytes. In mice, s.c. TRAPs induced local inflammation, leading to monocyte recruitment, and effectively bound to and were taken up by TfR1high monocytes, inducing both differentiation into mo-DCs and HEV-mediated trafficking to draining lymph nodes, where mRNA translation and antigen presentation occurred. In tumor models, TRAP-mRNA vaccines elicited strong, antigen-specific, cytotoxic T cell responses, and reduced tumor progression.

Contributed by Lauren Hitchings

To improve mRNA vaccine delivery to lymph nodes, Ren, Zhao, and Zhou et al. developed a DTC-modified, PEI-based, transferrin receptor-associating polyplex (TRAP) that enters cells by binding to TfR1, which is highly expressed on monocytes. In mice, s.c. TRAPs induced local inflammation, leading to monocyte recruitment, and effectively bound to and were taken up by TfR1high monocytes, inducing both differentiation into mo-DCs and HEV-mediated trafficking to draining lymph nodes, where mRNA translation and antigen presentation occurred. In tumor models, TRAP-mRNA vaccines elicited strong, antigen-specific, cytotoxic T cell responses, and reduced tumor progression.

Contributed by Lauren Hitchings

ABSTRACT: Lymph nodes are the primary sites where adaptive immunity is initiated, yet most messenger RNA cancer vaccines reach them inefficiently and instead accumulate in organs such as the liver, limiting therapeutic potency and increasing systemic toxicity. Here we developed a transferrin receptor-associating polyplex formed by electrostatic complexation of mRNA with low-molecular-weight polyethylenimine that had been chemically modified with cyclic disulfide monomers to enhance nucleic acid binding stability, enable thiol-based transferrin receptor engagement and reduce off-target liver uptake. After subcutaneous administration, these polyplexes activated innate immunity, rapidly recruited monocytes with high transferrin receptor expression and bound these cells through cyclic disulfide-mediated interactions. Monocytes then trafficked the vaccine to draining lymph nodes, where mRNA translation and antigen presentation occurred. Delivery of ovalbumin and interleukin 12 mRNA elicited strong antigen-specific cytotoxic T cell responses and inhibited melanoma progression and metastatic disease. Studies using Survivin and human papillomavirus antigens in distinct tumour models demonstrated broad applicability. This monocyte-driven lymph node-targeting strategy enables potent and selective delivery of mRNA cancer vaccines.

Author Info: 1Biomedical Polymers Laboratory, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, P. R. China. 2Institutes of Biology and Medical Scien

Author Info: 1Biomedical Polymers Laboratory, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, P. R. China. 2Institutes of Biology and Medical Science, Soochow University, Suzhou, P. R. China. 3Catug Biotechnology Co. Ltd, Suzhou, P. R. China. 4Department of Biosciences and Bioinformatics, School of Science, Xi'an Jiaotong-Liverpool University, Suzhou, P. R. China. 5School of Pharmacy, Shanghai Jiao Tong University, Shanghai, P. R. China. 6College of Pharmaceutical Sciences, Soochow University, Suzhou, P. R. China. 7Suzhou Abogen Biosciences Co. Ltd, Suzhou, P. R. China. 8Institutes of Biology and Medical Science, Soochow University, Suzhou, P. R. China. zhoufangfang@suda.edu.cn. 9Biomedical Polymers Laboratory, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, P. R. China. xucc@suda.edu.cn. 10College of Pharmaceutical Sciences, Soochow University, Suzhou, P. R. China. xucc@suda.edu.cn. 11International College of Pharmaceutical Innovation, Soochow University, Suzhou, P. R. China. xucc@suda.edu.cn. 12Biomedical Polymers Laboratory, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, P. R. China. zyzhong@suda.edu.cn. 13College of Pharmaceutical Sciences, Soochow University, Suzhou, P. R. China. zyzhong@suda.edu.cn. 14International College of Pharmaceutical Innovation, Soochow University, Suzhou, P. R. China. zyzhong@suda.edu.cn. #Contributed equally.

Ferroptosis-armed dendritic cell vaccines for glioma immunotherapy

A prophylactic DC vaccine loaded with ferroptotic (iron-dependent cell death) glioma cell line lysates protected against glioma growth in mice, superior to immunogenic cell death (ICD) or freeze/thaw (non-ICD) lysates. The vaccine also mediated therapeutic efficacy, induced antigen-specific CTL responses in SLOs, and increased i.t. CTLs (particularly CD39+ effector-memory cells) compared to controls. Ferroptosis induced ICD markers on glioma cells, and blocking calreticulin or ATP, but not HMGB1, abrogated vaccine efficacy. Ferroptotic lysates activated DCs and displayed a unique proteomic profile, potentially presenting novel TAAs.

Contributed by Alex Najibi

A prophylactic DC vaccine loaded with ferroptotic (iron-dependent cell death) glioma cell line lysates protected against glioma growth in mice, superior to immunogenic cell death (ICD) or freeze/thaw (non-ICD) lysates. The vaccine also mediated therapeutic efficacy, induced antigen-specific CTL responses in SLOs, and increased i.t. CTLs (particularly CD39+ effector-memory cells) compared to controls. Ferroptosis induced ICD markers on glioma cells, and blocking calreticulin or ATP, but not HMGB1, abrogated vaccine efficacy. Ferroptotic lysates activated DCs and displayed a unique proteomic profile, potentially presenting novel TAAs.

Contributed by Alex Najibi

ABSTRACT: The type of cell death has proven to play a crucial role in cancer immunotherapy efficacy. Immunogenic cell death (ICD) enhances tumor adjuvanticity and antigenicity by releasing danger signals and altering the immune peptidome. The immunogenicity of ferroptosis, an iron-dependent form of cell death, remains uncertain. Here, we show that dendritic cell (DC) vaccines loaded with ferroptotic lysates protect mice against glioma growth, inducing IFN-_ production, and promoting robust CD8_ T cell infiltration, activation, and effector memory formation in the tumor microenvironment. The intrinsic immunogenicity of ferroptosis was independent of the glioma type and the ferroptosis inducer. Instead, it critically required the presence of the damage-associated molecular patterns calreticulin and ATP, rather than involving HMGB1-TLR4 signaling. However, supplementing these DAMPs into DC vaccines loaded with non-ICD lysates did not restore efficacy to the level of the ferroptosis-based DC vaccine, suggesting a more complex mechanism beyond a purely DAMP-mediated effect. These findings demonstrate that ferroptosis-loaded DC vaccines elicit a potent, tumor-specific immune response, capable of eradicating intracranial gliomas in mice, which highlights their potential in cancer immunotherapy.

Author Info: 1Cell Death Investigation and Therapy (CDIT) Laboratory, Anatomy and Embryology Unit, Department of Human Structure and Repair, Faculty of Medicine and Health Sciences, Ghent Unive

Author Info: 1Cell Death Investigation and Therapy (CDIT) Laboratory, Anatomy and Embryology Unit, Department of Human Structure and Repair, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium. 2Cancer Research Institute Ghent, Ghent, Belgium. 3Institute of Neurosciences, National Research Lobachevsky State University of Nizhny Novgorod, Nizhny, Russia. 4Thoracic Tumor Immunology Laboratory (TTIL), Department of Internal Medicine and Pediatrics, Faculty of Medicine and Health Science, Ghent University, Ghent, Belgium. 5VIB Proteomics Core, VIB, Ghent, Belgium. 6VIB-UGent Center for Medical Biotechnology, VIB, Ghent, Belgium. 7Department of Biomolecular Medicine, Ghent University, Ghent, Belgium. 8myNEO Therapeutics, Ghent, Belgium. 9IBiTech-MEDISIP-Infinity Laboratory, Department of Electronics and Information Systems, Faculty of Engineering and Architecture, Ghent University, Ghent, Belgium. 10Clinical Cooperation Unit (CCU) Neuroimmunology and Brain Tumor Immunology, German Cancer Research Center (DKFZ), Heidelberg, Germany. 11Neurology Clinic, Medical Faculty Mannheim, University Heidelberg, Mannheim, Germany. 12Université Paris Cité, INSERM, CNRS, Institut Necker Enfants Malades, Paris, France. 13Service Immunologie Biologique, AP-HP, Hôpital Universitaire Necker-Enfants Malades, Paris, France. 144Brain, Department of Head and Skin, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium. 15Institute of Biology and Biomedicine, National Research Lobachevsky State University of Nizhny Novgorod, Nizhny, Russia. 16VIB Center for Inflammation Research, Ghent, Belgium. 17Department of Biomedical Molecular Biology, Faculty of Sciences, Ghent University, Ghent, Belgium. 18Cell Death Investigation and Therapy (CDIT) Laboratory, Anatomy and Embryology Unit, Department of Human Structure and Repair, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium. elena.catanzaro@ugent.be. 19Cancer Research Institute Ghent, Ghent, Belgium. elena.catanzaro@ugent.be. #Contributed equally.

Intermetallic nanoassemblies potentiate systemic STING activation

Zhou, and Ling et al. engineered CRYSTAL, a crystal-like STING-activating nanoassembly, to stabilize a STING agonist and enhance STING signaling at lower doses. Intravenous CRYSTAL activated myeloid cells, remodeled immunosuppressive tumor microenvironments, and primed host STING-dependent CD8+ T cell responses, driving durable tumor regression in advanced murine and rabbit models. Across mice, dogs, and non-human primates, CRYSTAL induced potent, but transient interferon responses, without cytokine release syndrome. Ex vivo treatment of human head and neck cancer biopsies triggered strong interferon signaling.

Contributed by Shishir Pant

Zhou, and Ling et al. engineered CRYSTAL, a crystal-like STING-activating nanoassembly, to stabilize a STING agonist and enhance STING signaling at lower doses. Intravenous CRYSTAL activated myeloid cells, remodeled immunosuppressive tumor microenvironments, and primed host STING-dependent CD8+ T cell responses, driving durable tumor regression in advanced murine and rabbit models. Across mice, dogs, and non-human primates, CRYSTAL induced potent, but transient interferon responses, without cytokine release syndrome. Ex vivo treatment of human head and neck cancer biopsies triggered strong interferon signaling.

Contributed by Shishir Pant

ABSTRACT: Natural systems use metal ions to form ordered structures that regulate biological processes, inspiring the rational design of nanotherapeutics. The cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) pathway drives antitumor immunity but has been difficult to activate systemically owing to poor pharmacology and toxicity. Here, we report CRYSTAL, a structurally ordered intermetallic nanoparticle for potent systemic STING activation. CRYSTAL self-assembles from manganese ions intercalated with cyclic dinucleotides, enabling precise structural control. At an ultralow intravenous dose (0.003 milligrams per kilogram), CRYSTAL activated STING in mice, dogs, and nonhuman primates without cytokine release syndrome. CRYSTAL induced robust tumor regression in advanced murine and rabbit models, remodeled immunosuppressive environments, and promoted host STING-dependent CD8(+) T cell priming. CRYSTAL activated interferon responses in human head and neck squamous cell carcinoma biopsies, underscoring its translational potential for cancer immunotherapy.

Author Info: 1Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, MI, USA. 2Biointerfaces Institute, University of Michigan, Ann Arbor, MI, USA. 3Department of Chemical En

Author Info: 1Department of Pharmaceutical Sciences, University of Michigan, Ann Arbor, MI, USA. 2Biointerfaces Institute, University of Michigan, Ann Arbor, MI, USA. 3Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, USA. 4Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan Medical Center, University of Michigan Medical School, Ann Arbor, MI, USA. 5Department of Head and Neck Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX, USA. 6Department of Microbiology, Genetics, and Immunology, Michigan State University, East Lansing, MI, USA. 7Department of Small Animal Clinical Sciences, Michigan State University, East Lansing, MI, USA. 8Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, MI, USA. 9Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA. 10Rogel Cancer Center, University of Michigan, Ann Arbor, MI, USA. #Contributed equally.

In vivo reprogramming of cytotoxic effector CD8+ T cells via fractalkine-conjugated mRNA-LNP

Corrigan et al. developed and tested mRNA lipid nanoparticles (mRNA-LNP) conjugated with fractalkine (CX3CL1) and found that they were able to specifically target CX3CR1+ cells – primarily effector T cells and NK cells – inducing transient expression of the payload mRNA. Administration of fraktalkine-conjugated mRNA-LNPs could be used to induce secretion of IL-2 or cell membrane expression of CD62L in target cells in vivo, with detectable expression of payload expression in up to 95% and 100% of Teff in the peripheral blood of mice and rhesus macaques, respectively. CD62L expression may have enabled lymph node trafficking of CX3CR1+ Teff cells.

Contributed by Lauren Hitchings

Corrigan et al. developed and tested mRNA lipid nanoparticles (mRNA-LNP) conjugated with fractalkine (CX3CL1) and found that they were able to specifically target CX3CR1+ cells – primarily effector T cells and NK cells – inducing transient expression of the payload mRNA. Administration of fraktalkine-conjugated mRNA-LNPs could be used to induce secretion of IL-2 or cell membrane expression of CD62L in target cells in vivo, with detectable expression of payload expression in up to 95% and 100% of Teff in the peripheral blood of mice and rhesus macaques, respectively. CD62L expression may have enabled lymph node trafficking of CX3CR1+ Teff cells.

Contributed by Lauren Hitchings

ABSTRACT: Selective in vivo reprogramming of cytotoxic effector CD8 T (Teff) cells holds tremendous promise as a therapeutic tool but has not yet been accomplished. Here, we demonstrate that fractalkine-conjugated mRNA lipid nanoparticles (mRNA-LNPs) can specifically target and deliver mRNA to CX3CR1+ Teff cells in vitro and in vivo. In mice, fractalkine-conjugated mRNA-LNPs targeted up to 95% of blood and splenic Teff cells. In addition, delivery of IL-2-encoding mRNA and human CD62L-encoding mRNA to mouse Teff cells enabled robust exogenous IL-2 secretion and CD62L expression. In rhesus macaques, fractalkine-conjugated mRNA-LNPs targeted up to ~100% of peripheral blood Teff cells, and delivery of human CD62L-encoding mRNA enabled cell-surface human CD62L expression on peripheral blood Teff cells and detection of human CD62L+ Teff cells in lymphoid tissue. Collectively, these data demonstrate the potential of natural receptor ligand-based targeting of mRNA-LNPs for rapid, efficient, and transient in vivo modification of Teff cells.

Author Info: 1Department of Microbiology, University of Pennsylvania, Philadelphia, PA, USA. 2Institute for Immunology and Immune Health, Perelman School of Medicine, University of Pennsylvania

Author Info: 1Department of Microbiology, University of Pennsylvania, Philadelphia, PA, USA. 2Institute for Immunology and Immune Health, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. 3Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. 4Parker Institute for Cancer Immunotherapy, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. 5Division of Microbiology and Immunology, Emory National Primate Research Center, Emory University, Atlanta, GA, USA. 6Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA. 7Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA. 8Division of Animal Resources, Emory National Primate Research Center, Emory University, Atlanta, GA, USA. 9Acuitas Therapeutics, Vancouver, Canada. 10Vaccine and Immunotherapy Center, Wistar Institute, Philadelphia, PA, USA. 11Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA, USA. 12Center for AIDS Research, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.

mRNA vaccine immunity is enhanced by hepatocyte detargeting and not dependent on dendritic cell expression Spotlight 

To study how cell type-specific expression on mRNA-encoded proteins influences immunity, Marks and Siu et al. incorporated synthetic microRNA target sites into the mRNA. LNP-delivered mRNA did not need to be directly expressed in professional APCs (pAPCs), and expression in muscle cells was sufficient or stronger in immune response induction than pAPCs. mRNA expression in hepatocytes dampened the CD8+ T cell response and reduced mRNA vaccine control of tumor growth. Silencing mRNA expression in hepatocytes reversed these effects and, when mRNA vaccines were used to expand transferred T cells, reduced liver T cell infiltration and toxicity.

Contributed by Ute Burkhardt

To study how cell type-specific expression on mRNA-encoded proteins influences immunity, Marks and Siu et al. incorporated synthetic microRNA target sites into the mRNA. LNP-delivered mRNA did not need to be directly expressed in professional APCs (pAPCs), and expression in muscle cells was sufficient or stronger in immune response induction than pAPCs. mRNA expression in hepatocytes dampened the CD8+ T cell response and reduced mRNA vaccine control of tumor growth. Silencing mRNA expression in hepatocytes reversed these effects and, when mRNA vaccines were used to expand transferred T cells, reduced liver T cell infiltration and toxicity.

Contributed by Ute Burkhardt

ABSTRACT: Proteins encoded by mRNA vaccines can be expressed by a diversity of transfected cell types but how cell-type-specific expression influences immunity is poorly understood. To investigate this, we incorporated synthetic microRNA target sites (miRT) into lipid nanoparticle (LNP)-delivered mRNA vaccines to silence mRNA expression specifically in professional antigen-presenting cells (pAPCs), hepatocytes or myocytes. We found that mRNA expression in pAPCs was dispensable for priming antigen-specific T cells, whereas mRNA expression in myocytes induced similar or stronger immune responses, including for SARS-CoV-2, suggesting that antigen cross-presentation or cross-dressing may be more impactful than direct mRNA expression in pAPCs. In contrast, mRNA expression in hepatocytes suppressed the antigen-specific T cell response, partly through PD1/PDL1. In mice bearing tumor-associated antigen (TAA)-expressing lymphoma cells, miRT-mediated hepatocyte-silenced TAA mRNA vaccine enhanced immune response and reduced tumor burden. Thus, non-pAPC expression shapes immunity to mRNA-encoded protein and inclusion of miRTs can boost or blunt mRNA-LNP immunogenicity.

Author Info: (1) Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA

Author Info: (1) Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Immunology and Immunotherapy, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (2) Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Immunology and Immunotherapy, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (3) Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Immunology and Immunotherapy, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (4) Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Immunology and Immunotherapy, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (5) Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (6) Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (7) Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (8) Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Immunology and Immunotherapy, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (9) Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Biomedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (10) Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Biomedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (11) Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Immunology and Immunotherapy, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (12) Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Immunology and Immunotherapy, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (13) Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Immunology and Immunotherapy, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (14) Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Immunology and Immunotherapy, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (15) Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Department of Immunology and Immunotherapy, Icahn School of Medicine at Mount Sinai, New York, NY, USA. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. (16) Icahn Genomics Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. brian.brown@mssm.edu. Precision Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. brian.brown@mssm.edu. Department of Immunology and Immunotherapy, Icahn School of Medicine at Mount Sinai, New York, NY, USA. brian.brown@mssm.edu. Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA. brian.brown@mssm.edu.

Dendritic cell redundancy enables priming of anti-tumor CD4+ T cells in pancreatic cancer

Spotlight 

Kureshi et al. showed that localized STING agonist combined with anti-CTLA-4 and anti-PD-1 induced durable tumor remission and memory in poorly immunogenic subcutaneous and orthotopic PDAC models, including β2m-/- tumors. Triple therapy increased activated cDC2-to-cDC1 ratios and cDC2 accumulation. Tumor control required tumor antigen-loaded cDC2 priming of IFNγ-producing Th1 CD4+ T cells in tumor-draining lymph nodes, but was independent of cDC1s, CD8+ T cells, and tumor cell MHC-I. In multiagent chemotherapy-treated PDAC patients, CD4+ T cells and cDC2s persisted, even after treatment.

Contributed by Shishir Pant

Kureshi et al. showed that localized STING agonist combined with anti-CTLA-4 and anti-PD-1 induced durable tumor remission and memory in poorly immunogenic subcutaneous and orthotopic PDAC models, including β2m-/- tumors. Triple therapy increased activated cDC2-to-cDC1 ratios and cDC2 accumulation. Tumor control required tumor antigen-loaded cDC2 priming of IFNγ-producing Th1 CD4+ T cells in tumor-draining lymph nodes, but was independent of cDC1s, CD8+ T cells, and tumor cell MHC-I. In multiagent chemotherapy-treated PDAC patients, CD4+ T cells and cDC2s persisted, even after treatment.

Contributed by Shishir Pant

ABSTRACT: Pancreatic ductal adenocarcinoma (PDAC) is resistant to current immunotherapies and lacks effective anti-tumor CD8(+) T cells, which is potentially due to insufficient cross-presentation by cDC1s. Here, we combine a STING agonist with anti-CTLA-4 and anti-PD-1 to achieve durable remissions and immunologic memory in multiple mouse models of poorly immunogenic PDAC. We find that tumor control does not depend on CD8(+) T cells or tumor cell MHC expression but instead requires IFN_-producing CD4(+) T cells (Th1s) that are primed by dendritic cells in lymph nodes. The triple combination immunotherapy induces an accumulation of activated cDC2s carrying tumor antigen into tumor-draining lymph nodes; cDC2s are required for orthotopic tumor clearance. Intratumoral CD4(+) T cells and cDC2s remain present in treatment-naive and chemotherapy-exposed human PDAC. In chemotherapy-exposed patients' blood, cDC2s outnumber cDC1s by 10-fold. Therefore, therapeutic targeting of the cDC2-CD4(+) T cell-IFN_ axis could be efficacious in PDAC.

Author Info: (1) Harvard Medical School Program in Immunology, Boston, MA, USA; Massachusetts General Hospital, Department of Medicine, Division of Gastroenterology, Boston, MA, USA; Dana-Farbe

Author Info: (1) Harvard Medical School Program in Immunology, Boston, MA, USA; Massachusetts General Hospital, Department of Medicine, Division of Gastroenterology, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Cancer Immunology & Virology, Boston, MA, USA. (2) Massachusetts General Hospital, Department of Medicine, Division of Gastroenterology, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Cancer Immunology & Virology, Boston, MA, USA; Harvard Medical School Program in Virology, Boston, MA, USA. (3) Harvard Medical School Program in Immunology, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Cancer Immunology & Virology, Boston, MA, USA. (4) Dana-Farber Cancer Institute, Department of Cancer Immunology & Virology, Boston, MA, USA; Harvard Medical School, Boston, MA, USA. (5) Dana-Farber Cancer Institute, Department of Cancer Immunology & Virology, Boston, MA, USA. (6) Massachusetts General Hospital, Department of Medicine, Division of Gastroenterology, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Cancer Immunology & Virology, Boston, MA, USA; Harvard Medical School, Boston, MA, USA. (7) Brookline High School, Brookline, MA, USA. (8) Dana-Farber Cancer Institute, Department of Cancer Immunology & Virology, Boston, MA, USA; Harvard Medical School, Boston, MA, USA. (9) Dana-Farber Cancer Institute, Department of Cancer Immunology & Virology, Boston, MA, USA; Harvard Medical School, Boston, MA, USA. (10) Dana-Farber Cancer Institute, Department of Cancer Immunology & Virology, Boston, MA, USA; Harvard Medical School, Boston, MA, USA. (11) Harvard Medical School Program in Immunology, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Cancer Immunology & Virology, Boston, MA, USA. (12) Dana-Farber Cancer Institute, Department of Cancer Immunology & Virology, Boston, MA, USA. (13) Dana-Farber Cancer Institute, Department of Cancer Immunology & Virology, Boston, MA, USA. (14) Dana-Farber Cancer Institute, Department of Medical Oncology, Boston, MA, USA. (15) Dana-Farber Cancer Institute, Department of Medical Oncology, Boston, MA, USA. (16) Harvard Medical School, Boston, MA, USA; Brigham and Women's Hospital, Division of Surgical Oncology, Boston, MA, USA. (17) Harvard Medical School, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Medical Oncology, Boston, MA, USA. (18) Harvard Medical School, Boston, MA, USA; Brigham and Women's Hospital, Department of Pathology, Boston, MA, USA. (19) Harvard Medical School, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Medical Oncology, Boston, MA, USA. (20) Harvard Medical School, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Radiation Oncology, Boston, MA, USA. (21) Harvard Medical School, Boston, MA, USA; Brigham and Women's Hospital, Division of Surgical Oncology, Boston, MA, USA. (22) Harvard Medical School, Boston, MA, USA; Brigham and Women's Hospital, Division of Surgical Oncology, Boston, MA, USA. (23) Harvard Medical School, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Medical Oncology, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Oncologic Pathology, Boston, MA, USA. (24) Harvard Medical School, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Medical Oncology, Boston, MA, USA. (25) Harvard Medical School, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Medical Oncology, Boston, MA, USA. (26) Harvard Medical School, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Medical Oncology, Boston, MA, USA. (27) Harvard Medical School, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Radiation Oncology, Boston, MA, USA. (28) Harvard Medical School, Boston, MA, USA; Brigham and Women's Hospital, Division of Surgical Oncology, Boston, MA, USA. (29) Harvard Medical School, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Medical Oncology, Boston, MA, USA. (30) Harvard Medical School, Boston, MA, USA; Brigham and Women's Hospital, Department of Pathology, Boston, MA, USA. (31) Bristol Myers Squibb, Princeton, NJ, USA. (32) Bristol Myers Squibb, Princeton, NJ, USA. (33) Bristol Myers Squibb, Princeton, NJ, USA. (34) Harvard Medical School, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Medical Oncology, Boston, MA, USA. (35) Harvard Medical School Program in Immunology, Boston, MA, USA; Massachusetts General Hospital, Department of Medicine, Division of Gastroenterology, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Cancer Immunology & Virology, Boston, MA, USA. (36) Harvard Medical School Program in Immunology, Boston, MA, USA; Dana-Farber Cancer Institute, Department of Cancer Immunology & Virology, Boston, MA, USA. Electronic address: stephanie_dougan@dfci.harvard.edu.

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