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Immune checkpoint blockade (ICB) has demonstrated clinical success in 'inflamed' tumors with substantial T cell infiltrates, but tumors with an immune-desert tumor microenvironment (TME) fail to benefit. The tumor cell-intrinsic molecular mechanisms of the immune-desert phenotype remain poorly understood. Here, we demonstrated that inactivation of the polycomb-repressive complex 2 (PRC2) core components embryonic ectoderm development (EED) or suppressor of zeste 12 homolog (SUZ12), a prevalent genetic event in malignant peripheral nerve sheath tumors (MPNSTs) and sporadically in other cancers, drove a context-dependent immune-desert TME. PRC2 inactivation reprogramed the chromatin landscape that led to a cell-autonomous shift from primed baseline signaling-dependent cellular responses (e.g., IFN-[gamma] signaling) to PRC2regulated developmental and cellular differentiation transcriptional programs. Further, PRC2 inactivation led to diminished tumor immune infiltrates through reduced chemokine production and impaired antigen presentation and T cell priming, resulting in primary resistance to ICB. Intratumoral delivery of inactivated modified vaccinia virus Ankara (MVA) enhanced tumor immune infiltrates and sensitized PRC2-loss tumors to ICB. Our results identify molecular mechanisms of PRC2 inactivation-mediated, context-dependent epigenetic reprogramming that underline the immune-desert phenotype in cancer. Our studies also point to intratumoral delivery of immunogenic viruses as an initial therapeutic strategy to modulate the immune-desert TME and capitalize on the clinical benefit of ICB., Introduction Polycomb-repressive complex 2 (PRC2), consisting of core components of enhancer of zeste homolog 1/-2 (EZH1/2), embryonic ectoderm development (EED), and suppressor of zeste 12 homolog (SUZ12), establishes and maintains [...]

Stroke is a leading cause of death and long-term disability. T cells have been extensively studied for their dual role in regulating immunity and inflammation following stroke. In this issue of the JCI, Cai, Shi, et al. demonstrated that [CD8.sup.+] regulatory-like T cells ([CD8.sup.+] TRLs) are one of the earliest lymphocyte subtypes to enter the brain after experimental ischemic stroke. Using a mouse model of stroke and comprehensive experimental approaches, the authors found that [CD8.sup.+] TRLs reduced both brain damage and functional deficits in both young and aged mice. These unique early responding regulatory T cells may also play a role in a wide array of other T cell-mediated neurological disorders., T cell immunology in stroke Stroke is a leading cause of disability and death (1). Ischemic stroke is the predominant form of stroke, primarily caused by thrombosis or embolism that [...]

Stimulating an immune response against cancer through adoptive transfer of tumor-targeting lymphocytes has shown great promise in hematological malignancies, but clinical efficacy against many common solid epithelial cancers remains low. Targeting 'neoantigens'--the somatic mutations expressed only by tumor cells--might enable tumor destruction without causing undue damage to vital healthy tissues. Major challenges to targeting neoantigens with T cells include heterogeneity and variability in antigen processing and presentation of targets by tumors, and an incomplete understanding of which T cell qualities are essential for clinically effective therapies. Finally, the prospect of targeting somatic tumor mutations to promote T cell destruction of cancer must contend with the biology that not all tumor-expressed 'neoepitopes' actually generate neoantigens that can be functionally recognized and provoke an effective immune response. In this Review, we discuss the promise, progress and challenges for improving neoantigen-targeted T cell-based immunotherapies for cancer. This Review examines the promise, progress and challenges for developing personal T cell-based immunotherapies for cancer., Author(s): Tori N. Yamamoto [sup.1] [sup.2] [sup.3] , Rigel J. Kishton [sup.1] [sup.2] , Nicholas P. Restifo [sup.1] [sup.2] [sup.4] Author Affiliations: (1) Center for Cancer Research, National Cancer Institute [...]

Somatic mutations together with immunoediting drive extensive heterogeneity within non-small-cell lung cancer (NSCLC). Herein we examine heterogeneity of the T cell antigen receptor (TCR) repertoire. The number of TCR sequences selectively expanded in tumors varies within and between tumors and correlates with the number of nonsynonymous mutations. Expanded TCRs can be subdivided into TCRs found in all tumor regions (ubiquitous) and those present in a subset of regions (regional). The number of ubiquitous and regional TCRs correlates with the number of ubiquitous and regional nonsynonymous mutations, respectively. Expanded TCRs form part of clusters of TCRs of similar sequence, suggestive of a spatially constrained antigen-driven process. CD8.sup.+ tumor-infiltrating lymphocytes harboring ubiquitous TCRs display a dysfunctional tissue-resident phenotype. Ubiquitous TCRs are preferentially detected in the blood at the time of tumor resection as compared to routine follow-up. These findings highlight a noninvasive method to identify and track relevant tumor-reactive TCRs for use in adoptive T cell immunotherapy. A survey of T cell repertoire evolution in the tumors, healthy tissue and blood of patients with early-stage untreated lung cancer offers an opportunity to monitor and identify neoantigen-specific T cells for personalized immunotherapy., Author(s): Kroopa Joshi [sup.1] [sup.2] , Marc Robert de Massy [sup.1] , Mazlina Ismail [sup.3] , James L. Reading [sup.1] , Imran Uddin [sup.3] , Annemarie Woolston [sup.3] , Emine [...]

Atherosclerosis is driven by multifaceted contributions of the immune system within the circulation and at vascular focal sites. However, specific characteristics of dysregulated immune cells within atherosclerotic lesions that lead to clinical events such as ischemic stroke or myocardial infarction are poorly understood. Here, using single-cell proteomic and transcriptomic analyses, we uncovered distinct features of both T cells and macrophages in carotid artery plaques of patients with clinically symptomatic disease (recent stroke or transient ischemic attack) compared to asymptomatic disease (no recent stroke). Plaques from symptomatic patients were characterized by a distinct subset of CD4.sup.+ T cells and by T cells that were activated and differentiated. Moreover, some T cell subsets in these plaques presented markers of T cell exhaustion. Additionally, macrophages from these plaques contained alternatively activated phenotypes, including subsets associated with plaque vulnerability. In plaques from asymptomatic patients, T cells and macrophages were activated and displayed evidence of interleukin-1[beta] signaling. The identification of specific features of innate and adaptive immune cells in plaques that are associated with cerebrovascular events may enable the design of more precisely tailored cardiovascular immunotherapies. Single-cell proteomic and transcriptional profiling of atherosclerotic lesions from human carotid arteries reveals specific features of lesional T cells and macrophages associated with symptomatic disease., Author(s): Dawn M. Fernandez [sup.1] , Adeeb H. Rahman [sup.2] [sup.3] [sup.4] , Nicolas F. Fernandez [sup.3] , Aleksey Chudnovskiy [sup.2] , El-ad David Amir [sup.3] , Letizia Amadori [sup.4] [...]

Immunotherapies that block inhibitory checkpoint receptors on T cells have transformed the clinical care of patients with cancer.sup.1. However, whether the T cell response to checkpoint blockade relies on reinvigoration of pre-existing tumor-infiltrating lymphocytes or on recruitment of novel T cells remains unclear.sup.2-4. Here we performed paired single-cell RNA and T cell receptor sequencing on 79,046 cells from site-matched tumors from patients with basal or squamous cell carcinoma before and after anti-PD-1 therapy. Tracking T cell receptor clones and transcriptional phenotypes revealed coupling of tumor recognition, clonal expansion and T cell dysfunction marked by clonal expansion of CD8.sup.+CD39.sup.+ T cells, which co-expressed markers of chronic T cell activation and exhaustion. However, the expansion of T cell clones did not derive from pre-existing tumor-infiltrating T lymphocytes; instead, the expanded clones consisted of novel clonotypes that had not previously been observed in the same tumor. Clonal replacement of T cells was preferentially observed in exhausted CD8.sup.+ T cells and evident in patients with basal or squamous cell carcinoma. These results demonstrate that pre-existing tumor-specific T cells may have limited reinvigoration capacity, and that the T cell response to checkpoint blockade derives from a distinct repertoire of T cell clones that may have just recently entered the tumor. Following anti-PD-1 therapy in patients with basal or squamous cell carcinoma, the CD8.sup.+ T cell response largely consists of an expanded and exhausted repertoire of new T cell clones., Author(s): Kathryn E. Yost [sup.1] , Ansuman T. Satpathy [sup.1] [sup.2] [sup.3] , Daniel K. Wells [sup.3] , Yanyan Qi [sup.1] , Chunlin Wang [sup.4] , Robin Kageyama [sup.3] , [...]

A key mechanism of tumor resistance to immune cells is mediated by expression of peptide-loaded HLA class I molecule (HLA-E) in tumor cells, which suppresses NK cell activity via ligation of the NK inhibitory receptor CD94/NK group 2 member A (NKG2A). Gene expression data from approximately 10,000 tumor samples showed widespread HLAE expression, with levels correlating with those of KLRC1 (NKG2A) and KLRD1 (CD94). To bypass HLA-E inhibition, we developed a way to generate highly functional NK cells lacking NKG2A. Constructs containing a single-chain variable fragment derived from an anti-NKG2A antibody were linked to endoplasmic reticulum-retention domains. After retroviral transduction in human peripheral blood NK cells, these NKG2A protein expression blockers (PEBLs) abrogated NKG2A expression. The resulting [NKG2A.sup.null] NK cells had higher cytotoxicity against HLA-E-expressing tumor cells. Transduction of anti-NKG2A PEBL produced more potent cytotoxicity than interference with an anti-NKG2A antibody and prevented de novo NKG2A expression without affecting NK cell proliferation. In immunodeficient mice, [NKG2A.sup.null] NK cells were substantially more powerful than [NKG2A.sup.+] NK cells against HLA-E-expressing tumors. Thus, NKG2A downregulation evades the HLA-E cancer immune checkpoint and increases the antitumor activity of NK cell infusions. Because this strategy is easily adaptable to current protocols for clinicalgrade immune cell processing, its clinical testing is feasible and warranted., Introduction Immunotherapy has become a mainstay of contemporary oncology. Major clinical responses achieved with T cell immune-checkpoint inhibitors and chimeric antigen receptor-directed (CAR-directed) T lymphocytes (1, 2) encourage the evaluation [...]

BACKGROUND. Recent genomic and bioinformatic technological advances have made it possible to dissect the immune response to personalized neoantigens encoded by tumor-specific mutations. However, timely and efficient identification of neoantigens is still a major obstacle to personalized neoantigen-based cancer immunotherapy. METHODS. Two different pipelines of neoantigen identification were established in this study: (a) Clinical-grade targeted sequencing was performed in patients with refractory solid tumor, and mutant peptides with high variant allele frequency and predicted high HLA-binding affinity were synthesized de novo. (b) An inventory-shared neoantigen peptide library of common solid tumors was constructed, and patients' hotspot mutations were matched to the neoantigen peptide library. The candidate neoepitopes were identified by recalling memory T cell responses in vitro. Subsequently, neoantigen-loaded dendritic cell vaccines and neoantigen-reactive T cells were generated for personalized immunotherapy in 6 patients. RESULTS. Immunogenic neoepitopes were recognized by autologous T cells in 3 of 4 patients who used the de novo synthesis mode and in 6 of 13 patients who used the shared neoantigen peptide library. A metastatic thymoma patient achieved a complete and durable response beyond 29 months after treatment. Immune-related partial response was observed in another patient with metastatic pancreatic cancer. The remaining 4 patients achieved prolonged stabilization of disease with a median progression-free survival of 8.6 months. CONCLUSION. The current study provides feasible pipelines for neoantigen identification. Implementing these strategies to individually tailor neoantigens could facilitate neoantigen-based translational immunotherapy research. TRIAL REGISTRATION. ChiCTR.org ChiCTR-OIC-16010092, ChiCTR-OIC-17011275, ChiCTR-OIC-17011913; ClinicalTrials.gov NCT03171220. FUNDING. This work was funded by grants from the National Key Research and Development Program of China (2017YFC1308900), the National Major Projects for 'Major New Drugs Innovation and Development' (2018ZX09301048-003), the National Natural Science Foundation of China (81672367, 81572329, 81572601), and the Key Research and Development Program of Jiangsu Province (BE2017607)., Introduction T cell-based immunotherapy has been successfully used to treat many human solid cancers (1). Administering autologous tumorinfiltrating T lymphocytes (TILs) can lead to complete, durable tumor regressions in patients [...]

The serine/threonine kinases BRAF and CRAF are critical components of the MAPK signaling pathway that is activated in many cancer types. In approximately 1% of melanomas, BRAF or CRAF is activated through structural arrangements. We describe a metastatic melanoma with a GOLGA4-RAF1 fusion and pathogenic variants in catenin [beta]1 (CTNNB1) and cyclin-dependent kinase inhibitor 2A (CDKN2A). Anti-cytotoxic T-lymphocyte-associated protein 4/anti-programmed cell death 1 (anti-CTLA4/anti-PD-1) combination immunotherapy failed to control tumor progression. In the absence of other actionable variants, the patient was administered MEK inhibitor therapy on the basis of its potential action against RAF1 fusions. This resulted in a profound and clinically significant response. We demonstrated that GOLGA4-RAF1 expression was associated with ERK activation, elevated expression of the RAS/RAF downstream coeffector ETV5, and a high Ki67 index. These findings provide a rationale for the dramatic response to targeted therapy. This study shows that molecular characterization of treatment-resistant cancers can identify therapeutic targets and personalize therapy management, leading to improved patient outcomes., Introduction MAPK pathway activation is a hallmark of many cancers. Many genes in this pathway, including RAS, RAF (encoding the serine/ threonine kinases BRAF and CRAF), and MEK can contain [...]

Gastrointestinal stromal tumor (GIST) is the most common human sarcoma, frequently characterized by an oncogenic mutation in the KIT or PDGFRA gene. We performed RNA sequencing of 75 human GIST tumors from 75 patients, comprising what we believe to be the largest cohort of GISTs sequenced to date, in order to discover differences in the immune infiltrates of KIT- and PDGFRA-mutant GIST. Through bioinformatics, immunohistochemistry, and flow cytometry, we found that in PDGFRA-mutant GISTs, immune cells were more numerous and had higher cytolytic activity than in KIT-mutant GISTs. PDGFRA-mutant GISTs expressed many chemokines, such as CXCL14, at a significantly higher level when compared with KIT-mutant GISTs and exhibited more diverse driver-derived neoepitope:HLA binding, both of which may contribute to PDGFRA-mutant GIST immunogenicity. Through machine learning, we generated gene expression-based immune profiles capable of differentiating KIT- and PDGFRA-mutant GISTs, and identified additional immune features of high-PD-1and -PD-L1-expressing tumors across all GIST mutational subtypes, which may provide insight into immunotherapeutic opportunities and limitations in GIST., Introduction Gastrointestinal stromal tumor (GIST) is the most common sarcoma (1), often originating in the stomach or the small intestine. GIST is a paradigm for targeted molecular therapy, since the [...]

Across clinical trials, T cell expansion and persistence following adoptive cell transfer (ACT) have correlated with superior patient outcomes. Herein, we undertook a pan-cancer analysis to identify actionable ligand-receptor pairs capable of compromising T cell durability following ACT. We discovered that FASLG, the gene encoding the apoptosis-inducing ligand FasL, is overexpressed within the majority of human tumor microenvironments (TMEs). Further, we uncovered that Fas, the receptor for FasL, is highly expressed on patient-derived T cells used for clinical ACT. We hypothesized that a cognate Fas-FasL interaction within the TME might limit both T cell persistence and antitumor efficacy. We discovered that genetic engineering of Fas variants impaired in the ability to bind FADD functioned as dominant negative receptors (DNRs), preventing FasL-induced apoptosis in Fas-competent T cells. T cells coengineered with a Fas DNR and either a T cell receptor or chimeric antigen receptor exhibited enhanced persistence following ACT, resulting in superior antitumor efficacy against established solid and hematologic cancers. Despite increased longevity, Fas DNR-engineered T cells did not undergo aberrant expansion or mediate autoimmunity. Thus, T cell-intrinsic disruption of Fas signaling through genetic engineering represents a potentially universal strategy to enhance ACT efficacy across a broad range of human malignancies., Introduction Adoptive cell transfer (ACT) using genetically engineered T cells has entered the standard of care for patients with refractory B cell malignancies, including pediatric acute lymphoblastic leukemia (ALL) (1) [...]

The rising prevalence of allergies represents an increasing socioeconomic burden. A detailed understanding of the immunological mechanisms that underlie the development of allergic disease, as well as the processes that drive immune tolerance to allergens, will be instrumental in designing therapeutic strategies to treat and prevent allergic disease. Improved characterization of individual patients through the use of specific biomarkers and improved definitions of disease endotypes are paving the way for the use of targeted therapeutic approaches for personalized treatment. Allergen-specific immunotherapy and biologic therapies that target key molecules driving the Th2 response are already used in the clinic, and a wave of novel drug candidates are under development. In-depth analysis of the cells and tissues of patients treated with such targeted interventions provides a wealth of information on the mechanisms that drive allergies and tolerance to allergens. Here, we aim to deliver an overview of the current state of specific inhibitors used in the treatment of allergy, with a particular focus on asthma and atopic dermatitis, and provide insights into the roles of these molecules in immunological mechanisms of allergic disease., Immunological mechanisms of allergy and tolerance Allergic sensitization and type I and IV hypersensitivity reactions. Allergies develop as a result of an immune response to distinct environmental protein antigens, called [...]

Immune checkpoint inhibitors and adoptive transfer of gene-engineered T cells have emerged as novel therapeutic modalities for hard-to-treat solid tumors; however, many patients are refractory to these immunotherapies, and the mechanisms underlying tumor immune resistance have not been fully elucidated. By comparing the tumor microenvironment of checkpoint inhibition-sensitive and -resistant murine solid tumors, we observed that the resistant tumors had low immunogenicity. We identified antigen presentation by [CD11b.sup.+][F4/80.sup.+] tumor-associated macrophages (TAMs) as a key factor correlated with immune resistance. In the resistant tumors, TAMs remained inactive and did not exert antigen-presenting activity. Targeted delivery of a long peptide antigen to TAMs by using a nano- sized hydrogel (nanogel) in the presence of a TLR agonist activated TAMs, induced their antigen-presenting activity, and thereby transformed the resistant tumors into tumors sensitive to adaptive immune responses such as adoptive transfer of tumor-specific T cell receptor-engineered T cells. These results indicate that the status and function of TAMs have a significant impact on tumor immune sensitivity and that manipulation of TAM functions would be an effective approach for improving the efficacy of immunotherapies., Introduction Accumulating preclinical and clinical evidence has shown that inhibition of immune checkpoint proteins, such as cytotoxic lymphocyte- associated protein 4 (CTLA-4), programmed cell death receptor 1 (PD-1), and programmed [...]

The most frequent subtype of acute myeloid leukemia (AML) is defined by mutations in the nucleophosmin 1 (NPM1) gene. Mutated NPM1 ([DELTA]NPM1) is an attractive target for immunotherapy, since it is an essential driver gene and 4 bp frameshift insertions occur in the same hotspot in 30%-35% of AMLs, resulting in a C-terminal alternative reading frame of 11 aa. By searching the HLA class I ligandome of primary AMLs, we identified multiple [DELTA]NPM1-derived peptides. For one of these peptides, HLA-A*02:01-binding CLAVEEVSL, we searched for specific T cells in healthy individuals using peptide-HLA tetramers. Tetramer-positive [CD8.sup.+] T cells were isolated and analyzed for reactivity against primary AMLs. From one clone with superior antitumor reactivity, we isolated the T cell receptor (TCR) and demonstrated specific recognition and lysis of HLA-A*02:01-positive [DELTA]NPM1 AML after retroviral transfer to [CD8.sup.+] and [CD4.sup.+] T cells. Antitumor efficacy of TCR-transduced T cells was confirmed in immunodeficient mice engrafted with a human AML cell line expressing [DELTA]NPM1. In conclusion, the data show that [DELTA]NPM1-derived peptides are presented on AML and that CLAVEEVSL is a neoantigen that can be efficiently targeted on AML by [DELTA]NPM1 TCR gene transfer. Immunotherapy targeting [DELTA]NPM1 may therefore contribute to treatment of AML., Introduction Acute myeloid leukemia (AML) is characterized by accumulation of malignant myeloid precursor cells that are arrested in differentiation in the bone marrow. Standard therapy of AML consists of induction [...]

Despite its success in treating melanoma and hematological malignancies, adoptive cell therapy (ACT) has had only limited effects in solid tumors. This is due in part to a lack of specific antigen targets, poor trafficking and infiltration, and immunosuppression in the tumor microenvironment. In this study, we combined ACT with oncolytic virus vaccines (OVVs) to drive expansion and tumor infiltration of transferred antigen-specific T cells and demonstrated that the combination is highly potent for the eradication of established solid tumors. Consistent with other successful immunotherapies, this approach elicited severe autoimmune consequences when the antigen targeted was a self-protein. However, modulation of IFN-[alpha]/-[beta] signaling, either by functional blockade or rational selection of an OVV backbone, ameliorated autoimmune side effects without compromising antitumor efficacy. Our study uncovers a pathogenic role for IFN-[alpha]/-[beta] in facilitating autoimmune toxicity during cancer immunotherapy and presents a safe and powerful combinatorial regimen with immediate translational applications., Introduction Immunotherapy has become a powerful therapeutic paradigm in cancer treatment. [CD8.sup.+] T cells play a prominent role in tumor clearance, given their ability to selectively recognize tumor antigens and [...]

While immune checkpoint blockade leads to potent antitumor efficacy, it also leads to immune-related adverse events in cancer patients. These toxicities stem from systemic immune activation resulting in inflammation of multiple organs, including the gastrointestinal tract, lung, and endocrine organs. We developed a dual variable domain immunoglobulin of anti-CTLA4 antibody (anti-CTLA4 DVD, where CTLA4 is defined as cytotoxic T lymphocyte-associated antigen-4) possessing an outer tumor-specific antigen-binding site engineered to shield the inner anti-CTLA4-binding domain. Upon reaching the tumor, the outer domain was cleaved by membrane type-serine protease 1 (MT-SP1) present in the tumor microenvironment, leading to enhanced localization of CTLA4 blockade. Anti-CTLA4 DVD markedly reduced multiorgan immune toxicity by preserving tissue-resident Tregs in [Rag1.sup.-/-] mice that received naive donor [CD4.sup.+] T cells from WT C57BL/6j mice. Moreover, anti-CTLA4 DVD induced potent antitumor effects by decreasing tumor-infiltrating Tregs and increasing the infiltration of antigen-specific [CD8.sup.+] T lymphocytes in TRAMP-C2-bearing C57BL/6j mice. Treg depletion was mediated through the antibody-dependent cellular cytotoxicity (ADCC) mechanism, as anti-CTLA4 without the Fc[gamma]R-binding portion (anti- CTLA4 DANA) spared Tregs, preventing treatment-induced toxicities. In summary, our results demonstrate an approach to anti-CTLA4 blockade that depletes tumor-infiltrating, but not tissue-resident, Tregs, preserving antitumor effects while minimizing toxicity. Thus, our tumor-conditional anti-CTLA4 DVD provides an avenue for uncoupling antitumor efficacy from immunotherapy-induced toxicities., IntroductionImmune checkpoint inhibition (CPI) has demonstrated promising results in both preclinical models (1, 2) and in the clinic (3). Yet several issues remain and severely hinder the clinical benefits, including [...]

Lymphocyte immunotherapy (LIT) to treat recurrent miscarriage involves receipt of lymphocytes to a patient from a donor, usually the patient's male partner. Although the European Society of Human Reproduction and [...]

Tumor-associated myeloid cells maintain immunosuppressive microenvironments within tumors. Identification of myeloidspecific receptors to modulate tumor-associated macrophage and myeloid-derived suppressor cell (MDSC) functions remains challenging. The leukocyte immunoglobulin-like receptor B (LILRB) family members are negative regulators of myeloid cell activation. We investigated how LILRB targeting could modulate tumor-associated myeloid cell function. LILRB2 antagonism inhibited receptor-mediated activation of SHP1/2 and enhanced proinflammatory responses. LILRB2 antagonism also inhibited AKT and STAT6 activation in the presence of M-CSF and IL-4. Transcriptome analysis revealed that LILRB2 antagonism altered genes involved in cell cytoskeleton remodeling, lipid/cholesterol metabolism, and endosomal sorting pathways, as well as changed differentiation gene networks associated with inflammatory myeloid cells as opposed to their alternatively activated phenotype. LILRB2 blockade effectively suppressed granulocytic MDSC and Treg infiltration and significantly promoted in vivo antitumor effects of T cell immune checkpoint inhibitors. Furthermore, LILRB2 blockade polarized tumor-infiltrating myeloid cells from non-small cell lung carcinoma tumor tissues toward an inflammatory phenotype. Our studies suggest that LILRB2 can potentially act as a myeloid immune checkpoint by reprogramming tumor-associated myeloid cells and provoking antitumor immunity., IntroductionMacrophages not only mediate inflammation during infection but also suppress immunity during inflammation resolution (1) and promote immune escape within tumor microenvironments (2). The functional plasticity of macrophage phenotypes is [...]

Despite breakthroughs in immune checkpoint inhibitor (ICI) immunotherapy, not all human cancers respond to ICI immunotherapy and a large fraction of patients with the responsive types of cancers do not respond to current ICI immunotherapy. This clinical conundrum suggests that additional immune checkpoints exist. We report here that interferon regulatory factor 8 (IRF8) deficiency led to impairment of cytotoxic T lymphocyte (CTL) activation and allograft tumor tolerance. However, analysis of chimera mice with competitive reconstitution of WT and IRF8-KO bone marrow cells as well as mice with IRF8 deficiency only in T cells indicated that IRF8 plays no intrinsic role in CTL activation. Instead, IRF8 functioned as a repressor of osteopontin (OPN), the physiological ligand for CD44 on T cells, in [CD11b.sup.+][Ly6C.sup.lo] [Ly6G.sup.+] myeloid cells and OPN acted as a potent T cell suppressor. IRF8 bound to the Spp1 promoter to repress OPN expression in colon epithelial cells, and colon carcinoma exhibited decreased IRF8 and increased OPN expression. The elevated expression of OPN in human colon carcinoma was correlated with decreased patient survival. Our data indicate that myeloid and tumor cell-expressed OPN acts as an immune checkpoint to suppress T cell activation and confer host tumor immune tolerance., Introduction[CD8.sup.+] cytotoxic T lymphocytes (CTLs) are the central component of the host adaptive immune system. A typical [CD8.sup.+] T cell immune response starts from T cell receptor (TCR) recognition of [...]

The accrual of myeloid-derived suppressor cells (MDSCs) represents a major obstacle to effective immunotherapy in cancer patients, but the mechanisms underlying this process in the human setting remain elusive. Here, we describe a set of microRNAs (miR-146a, miR-155, miR-125b, miR-100, let-7e, miR-125a, miR-146b, miR-99b) that are associated with MDSCs and resistance to treatment with immune checkpoint inhibitors in melanoma patients. The miRs were identified by transcriptional analyses as being responsible for the conversion of monocytes into MDSCs ([CD14.sup.+][HLA-DR.sup.neg] cells) mediated by melanoma extracellular vesicles (EVs) and were shown to recreate MDSC features upon transfection. In melanoma patients, these miRs were increased in circulating [CD14.sup.+] monocytes, plasma, and tumor samples, where they correlated with the myeloid cell infiltrate. In plasma, their baseline levels clustered with the clinical efficacy of CTLA-4 or programmed cell death protein 1 (PD-1) blockade. Hence, MDSC-related miRs represent an indicator of MDSC activity in cancer patients and a potential blood marker of a poor immunotherapy outcome., IntroductionImmunotherapy with immune checkpoint inhibitors (ICIs) has achieved a remarkable improvement in overall survival (OS) in different tumor histologies, albeit the majority of patients display intrinsic resistance (1). The response [...]

Cancer cells evade the immune system through a variety of different mechanisms, including the inhibition of antitumor effector T cells via checkpoint ligand-receptor interaction. Moreover, studies have shown that blocking these checkpoint pathways can reinvigorate the antitumor immunity, thereby prompting the development of numerous checkpoint immunotherapies, several of which are now being approved to treat multiple types of cancer. However, only a fraction of patients achieves promising long-term outcomes in response to checkpoint inhibition, suggesting the existence of additional unknown tumor-induced immunosuppressive pathways. In this issue of theJCI, Klement and colleagues describe an additional pathway of T cell inhibition in cancer. Specifically, the authors demonstrate that downregulation of IRF8, a molecular determinant of apoptotic resistance, in tumor cells aborts repression of osteopontin, which in turn binds to its physiological receptor CD44 on activated T cells and suppresses their activation. These results suggest that osteopontin may act as another immune checkpoint and may serve as a target to expand the number of patients who respond to immune checkpoint inhibitor therapy., How do tumors escape immunological surveillance?The immune system plays a crucial role in destroying cancerous cells. However, cancer cells also evolve and gain the ability to escape immunological elimination. Mechanisms [...]

The disease remains highly lethal but advances in immunotherapy and targeted drugs bring a flicker of hope. The disease remains highly lethal but advances in immunotherapy and targeted drugs bring a flicker of hope., Author(s): Michael Eisenstein Author Affiliations: New lung-cancer drugs extend survival times Credit: Daniel Stolle Rather than using numbers, Tony Mok prefers a more anecdotal indicator to describe the shift in [...]

Cancer treatment by immune checkpoint blockade (ICB) can bring long-lasting clinical benefits, but only a fraction of patients respond to treatment. To predict ICB response, we developed TIDE, a computational method to model two primary mechanisms of tumor immune evasion: the induction of T cell dysfunction in tumors with high infiltration of cytotoxic T lymphocytes (CTL) and the prevention of T cell infiltration in tumors with low CTL level. We identified signatures of T cell dysfunction from large tumor cohorts by testing how the expression of each gene in tumors interacts with the CTL infiltration level to influence patient survival. We also modeled factors that exclude T cell infiltration into tumors using expression signatures from immunosuppressive cells. Using this framework and pre-treatment RNA-Seq or NanoString tumor expression profiles, TIDE predicted the outcome of melanoma patients treated with first-line anti-PD1 or anti-CTLA4 more accurately than other biomarkers such as PD-L1 level and mutation load. TIDE also revealed new candidate ICB resistance regulators, such as SERPINB9, demonstrating utility for immunotherapy research. An algorithm-selected gene signature focused on tumor immune evasion and suppression predicts response to immune checkpoint blockade in melanoma, exceeding the accuracy of current clinical biomarkers., Author(s): Peng Jiang [sup.1] [sup.2] , Shengqing Gu [sup.3] , Deng Pan [sup.4] [sup.5] , Jingxin Fu [sup.6] , Avinash Sahu [sup.1] [sup.2] , Xihao Hu [sup.1] [sup.2] , Ziyi [...]