T cells and natural killer (NK) cells have complementary roles in tumor immunity, and dual T cell and NK cell attack thus offers opportunities to deepen the impact of immunotherapy. Recent work has ...also shown that NK cells play an important role in recruiting dendritic cells to tumors and thus enhance induction of CD8 T cell responses, while IL-2 secreted by T cells activates NK cells. Targeting of immune evasion mechanisms from the activating NKG2D receptor and its MICA and MICB ligands on tumor cells offers opportunities for therapeutic intervention. Interestingly, T cells and NK cells share several important inhibitory and activating receptors that can be targeted to enhance T cell- and NK cell-mediated immunity. These inhibitory receptor-ligand systems include CD161-CLEC2D, TIGIT-CD155, and NKG2A CD94-HLA-E. We also discuss emerging therapeutic strategies based on inhibitory and activating cytokines that profoundly impact the function of both lymphocyte populations within tumors.
Interest in harnessing natural killer (NK) cells for cancer immunotherapy is rapidly growing. However, efficacy of NK cell-based immunotherapy remains limited in most trials. Strategies to augment ...the killing efficacy of NK cells are thus much needed. In the current study, we found that mitochondrial apoptosis (mtApoptosis) pathway is essential for efficient NK killing, especially at physiologically relevant effector-to-target ratios. Furthermore, NK cells can prime cancer cells for mtApoptosis and mitochondrial priming status affects cancer-cell susceptibility to NK-mediated killing. Interestingly, pre-activating NK cells confers on them resistance to BH3 mimetics. Combining BH3 mimetics with NK cells synergistically kills cancer cells in vitro and suppresses tumor growth in vivo. The ideal BH3 mimetic to use in such an approach can be predicted by BH3 profiling. We herein report a rational and precision strategy to augment NK-based immunotherapy, which may be adaptable to T cell-based immunotherapies as well.
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•Mitochondrial readiness for apoptosis affects cancer cell sensitivity to NK cells•Pre-activated NK cells acquire resistance to BCL-2, MCL-1, and BCL-XL inhibitors•BH3 mimetics and NK cells synergize in killing cancer cells in vitro and in vivo•BH3 profiling of cancer cells identifies which BH3 mimetic augments NK killing
NK cells are an attractive option for cell-based therapy but require optimization. BH3 mimetics chosen by BH3 profiling synergized with NK cell therapy to enhance cancer-cell killing by NK cells in an approach that could also be used for other cell therapy platforms.
During the past decade, immunotherapies have made a major impact on the treatment of diverse types of cancer. Inflammatory toxicities are not only a major concern for Food and Drug Administration ...(FDA)-approved checkpoint blockade and chimeric antigen receptor (CAR) T cell therapies, but also limit the development and use of combination therapies. Fundamentally, these adverse events highlight the intricate balance of pro- and anti-inflammatory pathways that regulate protective immune responses. Here, we discuss the cellular and molecular mechanisms of inflammatory adverse events, current approaches to treatment, as well as opportunities for the design of immunotherapies that limit such inflammatory toxicities while preserving anti-tumor efficacy.
Inflammatory toxicities are critical challenges hindering the success of immunotherapy in revolutionizing oncology care. Understanding the biology of inflammatory adverse events will fuel the effort of advancing immunotherapy design that curbs toxicities without sacrificing anti-tumor efficacy.
Checkpoint blockade with antibodies specific for the PD-1 and CTLA-4 inhibitory receptors can induce durable responses in a wide range of human cancers. However, the immunological mechanisms ...responsible for severe inflammatory side effects remain poorly understood. Here we report a comprehensive single-cell analysis of immune cell populations in colitis, a common and severe side effect of checkpoint blockade. We observed a striking accumulation of CD8 T cells with highly cytotoxic and proliferative states and no evidence of regulatory T cell depletion. T cell receptor (TCR) sequence analysis demonstrated that a substantial fraction of colitis-associated CD8 T cells originated from tissue-resident populations, explaining the frequently early onset of colitis symptoms following treatment initiation. Our analysis also identified cytokines, chemokines, and surface receptors that could serve as therapeutic targets for colitis and potentially other inflammatory side effects of checkpoint blockade.
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•Mechanisms of inflammatory adverse events induced by checkpoint blockade•Colitis-associated differentiation of CD8 Trm cells to cytotoxic effector cells•Persistence and expansion of CTLA-4+ Treg cells•Inflammatory pathways provide opportunities for therapeutic intervention
Single-cell analyses of immune checkpoint blockade-associated colitis patient samples reveal enrichment of regulatory T cells in colitic lesions and nominate inflammatory pathways for potential therapeutic intervention.
Targeted delivery of compounds to particular cell subsets can enhance therapeutic index by concentrating their action on the cells of interest. Because attempts to target tumors directly have yielded ...limited benefit, we instead target endogenous immune cell subsets in the circulation that can migrate actively into tumors. We describe antibody-targeted nanoparticles that bind to CD8
T cells in the blood, lymphoid tissues, and tumors of mice. PD-1
T cells are successfully targeted in the circulation and tumor. The delivery of an inhibitor of TGFβ signaling to PD-1-expressing cells extends the survival of tumor-bearing mice, whereas free drugs have no effect at such doses. This modular platform also enables PD-1-targeted delivery of a TLR7/8 agonist to the tumor microenvironment, increasing the proportion of tumor-infiltrating CD8
T cells and sensitizing tumors to subsequent anti-PD-1. Targeted delivery of immunotherapy to defined subsets of endogenous leukocytes may be superior to administration of free drugs.
HLA-DR molecules bind microbial peptides in an endosomal compartment and present them on the cell surface for CD4 T cell surveillance. HLA-DM plays a critical role in the endosomal peptide selection ...process. The structure of the HLA-DM–HLA-DR complex shows major rearrangements of the HLA-DR peptide-binding groove. Flipping of a tryptophan away from the HLA-DR1 P1 pocket enables major conformational changes that position hydrophobic HLA-DR residues into the P1 pocket. These conformational changes accelerate peptide dissociation and stabilize the empty HLA-DR peptide-binding groove. Initially, incoming peptides have access to only part of the HLA-DR groove and need to compete with HLA-DR residues for access to the P2 site and the hydrophobic P1 pocket. This energetic barrier creates a rapid and stringent selection process for the highest-affinity binders. Insertion of peptide residues into the P2 and P1 sites reverses the conformational changes, terminating selection through DM dissociation.
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► Structure of HLA-DM-HLA-DR1 complex identifies key steps in antigen presentation ► Two aromatic HLA-DR residues move in and stabilize the hydrophobic P1 pocket ► Occlusion of P1 pocket enables rapid selection of high-affinity peptides ► Only peptides that successfully compete for the P1 pocket are stably bound
HLA-DM catalyzes the binding of microbial peptides to the MHC class II cell surface receptor HLA-DR, which then presents the antigen to T cells. Crystal structures of the HLA-DM-HLA-DR complex reveal how DM changes the conformation of DR so that it can very rapidly distinguish high- from low-affinity peptides.
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.
In order to survey a universe of major histocompatibility complex (MHC)-presented peptide antigens whose numbers greatly exceed the diversity of the T cell repertoire, T cell receptors (TCRs) are ...thought to be cross-reactive. However, the nature and extent of TCR cross-reactivity has not been conclusively measured experimentally. We developed a system to identify MHC-presented peptide ligands by combining TCR selection of highly diverse yeast-displayed peptide-MHC libraries with deep sequencing. Although we identified hundreds of peptides reactive with each of five different mouse and human TCRs, the selected peptides possessed TCR recognition motifs that bore a close resemblance to their known antigens. This structural conservation of the TCR interaction surface allowed us to exploit deep-sequencing information to computationally identify activating microbial and self-ligands for human autoimmune TCRs. The mechanistic basis of TCR cross-reactivity described here enables effective surveillance of diverse self and foreign antigens without necessitating degenerate recognition of nonhomologous peptides.
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•Deep sequencing peptide-MHC libraries finds hundreds of TCR-reactive peptides•TCRs exhibit limited cross-reactivity for contact residues in peptide antigens•Structures show linkages between distantly related peptide sequences•Novel strategy for identification of naturally occurring TCR ligands
Combinatorial pMHC libraries mated with deep-sequencing analysis reveal that peptide antigens recognized by a given T cell receptor are surprisingly homologous and show that it is possible to predict naturally occurring peptide ligands for TCRs of interest.
The mesenchymal subtype of glioblastoma is thought to be determined by both cancer cell-intrinsic alterations and extrinsic cellular interactions, but remains poorly understood. Here, we dissect ...glioblastoma-to-microenvironment interactions by single-cell RNA sequencing analysis of human tumors and model systems, combined with functional experiments. We demonstrate that macrophages induce a transition of glioblastoma cells into mesenchymal-like (MES-like) states. This effect is mediated, both in vitro and in vivo, by macrophage-derived oncostatin M (OSM) that interacts with its receptors (OSMR or LIFR) in complex with GP130 on glioblastoma cells and activates STAT3. We show that MES-like glioblastoma states are also associated with increased expression of a mesenchymal program in macrophages and with increased cytotoxicity of T cells, highlighting extensive alterations of the immune microenvironment with potential therapeutic implications.
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•Macrophages induce the MES-like state of glioblastoma cells•Induction is mediated by macrophage-derived OSM interacting with OSMR/LIFR-GP130•Subsets of glioblastoma-associated macrophages express a related MES-like program•The MES-like state in glioblastoma is associated with cytotoxic T cells programs
Hara et al. combine single-cell RNA sequencing and functional experiments to explore the crosstalk between glioblastoma and the microenvironment, revealing that macrophage-derived OSM induces the mesenchymal-like state of glioblastoma, a state associated with upregulation of major histocompatibility complex genes, and with potential implications for immunotherapy.
Gliomas with histone H3 lysine27-to-methionine mutations (H3K27M-glioma) arise primarily in the midline of the central nervous system of young children, suggesting a cooperation between genetics and ...cellular context in tumorigenesis. Although the genetics of H3K27M-glioma are well characterized, their cellular architecture remains uncharted. We performed single-cell RNA sequencing in 3321 cells from six primary H3K27M-glioma and matched models. We found that H3K27M-glioma primarily contain cells that resemble oligodendrocyte precursor cells (OPC-like), whereas more differentiated malignant cells are a minority. OPC-like cells exhibit greater proliferation and tumor-propagating potential than their more differentiated counterparts and are at least in part sustained by
signaling. Our study characterizes oncogenic and developmental programs in H3K27M-glioma at single-cell resolution and across genetic subclones, suggesting potential therapeutic targets in this disease.
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