Despite their cytotoxic capacity, neutrophils are often co-opted by cancers to promote immunosuppression, tumor growth, and metastasis. Consequently, these cells have received little attention as ...potential cancer immunotherapeutic agents. Here, we demonstrate in mouse models that neutrophils can be harnessed to induce eradication of tumors and reduce metastatic seeding through the combined actions of tumor necrosis factor, CD40 agonist, and tumor-binding antibody. The same combination activates human neutrophils in vitro, enabling their lysis of human tumor cells. Mechanistically, this therapy induces rapid mobilization and tumor infiltration of neutrophils along with complement activation in tumors. Complement component C5a activates neutrophils to produce leukotriene B4, which stimulates reactive oxygen species production via xanthine oxidase, resulting in oxidative damage and T cell-independent clearance of multiple tumor types. These data establish neutrophils as potent anti-tumor immune mediators and define an inflammatory pathway that can be harnessed to drive neutrophil-mediated eradication of cancer.
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•Therapeutically activated neutrophils infiltrate and eradicate multiple tumor types•Intratumoral TNF + anti-CD40 + anti-tumor antibodies induce an inflammatory cascade•Neutrophil C5AR1 signaling stimulates LTB4 release, driving ROS production via XO•Neutrophil-mediated oxidative damage drives T cell-independent tumor clearance
Linde et al. describe a cancer therapy that activates neutrophils to infiltrate and eradicate tumors and reduce metastatic seeding. The authors elucidate the responsible mechanism, which involves complement component C5a, leukotriene B4, and reactive oxygen species, and demonstrate the potential of harnessing neutrophils through inflammatory activation to drive tumor clearance.
The period between “successful” treatment of localized breast cancer and the onset of distant metastasis can last many years, representing an unexploited window to eradicate disseminated disease and ...prevent metastases. We find that the source of recurrence—disseminated tumor cells (DTCs) —evade endogenous immunity directed against tumor neoantigens. Although DTCs downregulate major histocompatibility complex I, this does not preclude recognition by conventional T cells. Instead, the scarcity of interactions between two relatively rare populations—DTCs and endogenous antigen-specific T cells—underlies DTC persistence. This scarcity is overcome by any one of three immunotherapies that increase the number of tumor-specific T cells: T cell-based vaccination, or adoptive transfer of T cell receptor or chimeric antigen receptor T cells. Each approach achieves robust DTC elimination, motivating discovery of MHC-restricted and -unrestricted DTC antigens that can be targeted with T cell-based immunotherapies to eliminate the reservoir of metastasis-initiating cells in patients.
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•We describe a phenomenon called “relative scarcity” that underlies DTC immunoevasion•DTCs and antigen-specific T cells interact too infrequently to clear DTCs•Boosting the frequency of these interactions results in DTC eradication•This can be accomplished by vaccination or by adoptive transfer of engineered T cells
Dormant disseminated tumor cells (DTCs) persist despite anti-tumor immunity. How these cells evade immunosurveillance is unknown. Goddard et al. reveal a previously unappreciated form of immunoevasion called “relative scarcity” that underlies DTC persistence. T cell-based immunotherapies increase interaction frequency between DTCs and antigen-specific T cells, leading to DTC depletion.
Patients with relapsed pediatric solid tumors and CNS malignancies have few therapeutic options and frequently die of their disease. Chimeric antigen receptor (CAR) T cells have shown tremendous ...success in treating relapsed pediatric acute lymphoblastic leukemia, but this has not yet translated to treating solid tumors. This is partially due to a paucity of differentially expressed cell surface molecules on solid tumors that can be safely targeted. Here, we present B7-H3 (CD276) as a putative target for CAR T-cell therapy of pediatric solid tumors, including those arising in the central nervous system.
We developed a novel B7-H3 CAR whose binder is derived from a mAb that has been shown to preferentially bind tumor tissues and has been safely used in humans in early-phase clinical trials. We tested B7-H3 CAR T cells in a variety of pediatric cancer models.
B7-H3 CAR T cells mediate significant antitumor activity
, causing regression of established solid tumors in xenograft models including osteosarcoma, medulloblastoma, and Ewing sarcoma. We demonstrate that B7-H3 CAR T-cell efficacy is largely dependent upon high surface target antigen density on tumor tissues and that activity is greatly diminished against target cells that express low levels of antigen, thus providing a possible therapeutic window despite low-level normal tissue expression of B7-H3.
B7-H3 CAR T cells could represent an exciting therapeutic option for patients with certain lethal relapsed or refractory pediatric malignancies, and should be tested in carefully designed clinical trials.
Therapeutic cancer vaccination seeks to elicit activation of tumor-reactive T cells capable of recognizing tumor-associated antigens (TAA) and eradicating malignant cells. Here, we present a cancer ...vaccination approach utilizing myeloid-lineage reprogramming to directly convert cancer cells into tumor-reprogrammed antigen-presenting cells (TR-APC). Using syngeneic murine leukemia models, we demonstrate that TR-APCs acquire both myeloid phenotype and function, process and present endogenous TAAs, and potently stimulate TAA-specific CD4+ and CD8+ T cells. In vivo TR-APC induction elicits clonal expansion of cancer-specific T cells, establishes cancer-specific immune memory, and ultimately promotes leukemia eradication. We further show that both hematologic cancers and solid tumors, including sarcomas and carcinomas, are amenable to myeloid-lineage reprogramming into TR-APCs. Finally, we demonstrate the clinical applicability of this approach by generating TR-APCs from primary clinical specimens and stimulating autologous patient-derived T cells. Thus, TR-APCs represent a cancer vaccination therapeutic strategy with broad implications for clinical immuno-oncology.
Despite recent advances, the clinical benefit provided by cancer vaccination remains limited. We present a cancer vaccination approach leveraging myeloid-lineage reprogramming of cancer cells into APCs, which subsequently activate anticancer immunity through presentation of self-derived cancer antigens. Both hematologic and solid malignancies derive significant therapeutic benefit from reprogramming-based immunotherapy. This article is highlighted in the In This Issue feature, p. 1027.
The disialoganglioside GD2 is overexpressed on several solid tumors, and monoclonal antibodies targeting GD2 have substantially improved outcomes for children with high-risk neuroblastoma. However, ...approximately 40% of patients with neuroblastoma still relapse, and anti-GD2 has not mediated significant clinical activity in any other GD2
malignancy. Macrophages are important mediators of anti-tumor immunity, but tumors resist macrophage phagocytosis through expression of the checkpoint molecule CD47, a so-called 'Don't eat me' signal. In this study, we establish potent synergy for the combination of anti-GD2 and anti-CD47 in syngeneic and xenograft mouse models of neuroblastoma, where the combination eradicates tumors, as well as osteosarcoma and small-cell lung cancer, where the combination significantly reduces tumor burden and extends survival. This synergy is driven by two GD2-specific factors that reorient the balance of macrophage activity. Ligation of GD2 on tumor cells (a) causes upregulation of surface calreticulin, a pro-phagocytic 'Eat me' signal that primes cells for removal and (b) interrupts the interaction of GD2 with its newly identified ligand, the inhibitory immunoreceptor Siglec-7. This work credentials the combination of anti-GD2 and anti-CD47 for clinical translation and suggests that CD47 blockade will be most efficacious in combination with monoclonal antibodies that alter additional pro- and anti-phagocytic signals within the tumor microenvironment.
Natural killer (NK) cells are effector cells of the innate immune system involved in defense against virus-infected and transformed cells. The effector function of NK cells is linked to their ability ...to migrate to sites of inflammation or damage. Therefore, understanding the factors regulating NK cell migration is of substantial interest. Here, we show that in the absence of aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, NK cells have reduced capacity to migrate and infiltrate tumors
. Analysis of differentially expressed genes revealed that ankyrin repeat and SOCS Box containing 2 (
) expression was dramatically decreased in
NK cells and that AhR ligands modulated its expression. Further, AhR directly regulated the promoter region of the
gene. Similar to what was observed with murine
NK cells,
knockdown inhibited the migration of human NK cells. Activation of AHR by its agonist FICZ induced ASB2-dependent filamin A degradation in NK cells; conversely, knockdown of endogenous
inhibited filamin A degradation. Reduction of filamin A increased the migration of primary NK cells and restored the invasion capacity of AHR-deficient NK cells. Our study introduces AHR as a new regulator of NK cell migration, through an AHR-ASB2-filamin A axis and provides insight into a potential therapeutic target for NK cell-based immunotherapies.
Ageing is characterized by the development of persistent pro-inflammatory responses that contribute to atherosclerosis, metabolic syndrome, cancer and frailty
. The ageing brain is also vulnerable to ...inflammation, as demonstrated by the high prevalence of age-associated cognitive decline and Alzheimer's disease
. Systemically, circulating pro-inflammatory factors can promote cognitive decline
, and in the brain, microglia lose the ability to clear misfolded proteins that are associated with neurodegeneration
. However, the underlying mechanisms that initiate and sustain maladaptive inflammation with ageing are not well defined. Here we show that in ageing mice myeloid cell bioenergetics are suppressed in response to increased signalling by the lipid messenger prostaglandin E
(PGE
), a major modulator of inflammation
. In ageing macrophages and microglia, PGE
signalling through its EP2 receptor promotes the sequestration of glucose into glycogen, reducing glucose flux and mitochondrial respiration. This energy-deficient state, which drives maladaptive pro-inflammatory responses, is further augmented by a dependence of aged myeloid cells on glucose as a principal fuel source. In aged mice, inhibition of myeloid EP2 signalling rejuvenates cellular bioenergetics, systemic and brain inflammatory states, hippocampal synaptic plasticity and spatial memory. Moreover, blockade of peripheral myeloid EP2 signalling is sufficient to restore cognition in aged mice. Our study suggests that cognitive ageing is not a static or irrevocable condition but can be reversed by reprogramming myeloid glucose metabolism to restore youthful immune functions.
Clinical, cytogenetic, and gene-based studies have been used to inform biology and improve prognostication for patients with acute myeloid leukemia (AML). Candidate gene and whole genome studies have ...identified recurrent somatic mutations in AML patients including TET2, DNMT3A, ASXL1, IDH1/2 and cohesin complex mutations. We have also investigated the role of epigenetic regulator mutations in AML pathogenesis, and shown these mutations cooperate with other disease alleles to induce leukemic transformation and to alter gene regulatory networks which impact self-renewal and differentiation. In addition, Recent studies of clonal hematopoiesis (CH) discovered a subset of AML disease alleles, most commonly in epigenetic modifiers, while other alleles are only observed in overt hematologic malignancies. These observations suggest an important pathogenetic role for the chronology of mutational acquisition. We will present novel data showing how sequential acquisition of somatic mutation dysregulates hematopoietic stem/progenitor cells in order to drive transformation and that these mutations have biologic, prognostic, and therapeutic relevance.
Acute myeloid leukemia (AML) is characterized by aberrant expansion of dysregulated myeloid progenitor cells. Genomic studies have identified somatic mutations with variable variant allele ...frequencies (VAF), suggestive of sequential clonal evolution with “newer”, low VAF, mutations altering the fitness of antecedent clones. Our single cell DNA-sequencing studies have shown that mutations in NPM1, NRAS and FLT3 are rarely found as mono-allelic clones and consistent with a late role in leukemic transformation and propagation. These studies revealed clonal evolutionary trajectories to AML, where NPM1c was present in the entire leukemic clone and FLT3-ITD mutations were subclonal. Despite being a late event, FLT3 mutations portend a poor prognosis particularly when co-mutant with DNMT3A and NPM1. Preclinical FLT3 mutant models have employed constitutive expression or retroviral overexpression precluding evaluation of FLT3 mutations in the context observed in AML patients. Here, we report the development of a Flpo-inducible Flt3-ITD allele which allows somatic mutation acquisition subsequent to antecedent disease alleles. Activation of Flt3-ITD induced marked myeloproliferation in vivo. In competitive transplantation studies Flt3-ITD-mutant cells initiated disease at the expense of wild-type HSPCs. Despite these findings, disease was incapable of transplanting into secondary recipients, consistent with the observed depletion of SLAM+ LSK cells. This suggests the FLlt3-ITD cannot propagate disease in self-renewing stem cells. By contrast, acquisition of the Flt3-ITD in NPM1 or DNMT3A mutant HPSCs induced fully penetrant, transplantable AML with immunophenotypic characteristics seen in human AML with these same genotypes. These studies provide mechanistic insights into FLT3-mutant leukemogenesis and offer a preclinical platform for testing novel AML therapies.
Approximately 200 BRAF mutant alleles have been identified in human tumours. Activating BRAF mutants cause feedback inhibition of GTP-bound RAS, are RAS-independent and signal either as active ...monomers (class 1) or constitutively active dimers (class 2). Here we characterize a third class of BRAF mutants-those that have impaired kinase activity or are kinase-dead. These mutants are sensitive to ERK-mediated feedback and their activation of signalling is RAS-dependent. The mutants bind more tightly than wild-type BRAF to RAS-GTP, and their binding to and activation of wild-type CRAF is enhanced, leading to increased ERK signalling. The model suggests that dysregulation of signalling by these mutants in tumours requires coexistent mechanisms for maintaining RAS activation despite ERK-dependent feedback. Consistent with this hypothesis, melanomas with these class 3 BRAF mutations also harbour RAS mutations or NF1 deletions. By contrast, in lung and colorectal cancers with class 3 BRAF mutants, RAS is typically activated by receptor tyrosine kinase signalling. These tumours are sensitive to the inhibition of RAS activation by inhibitors of receptor tyrosine kinases. We have thus defined three distinct functional classes of BRAF mutants in human tumours. The mutants activate ERK signalling by different mechanisms that dictate their sensitivity to therapeutic inhibitors of the pathway.
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