scholarly journals Interleukin-15 after Near-Infrared Photoimmunotherapy (NIR-PIT) Enhances T Cell Response against Syngeneic Mouse Tumors

Cancers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2575 ◽  
Author(s):  
Yasuhiro Maruoka ◽  
Aki Furusawa ◽  
Ryuhei Okada ◽  
Fuyuki Inagaki ◽  
Hiroaki Wakiyama ◽  
...  
Keyword(s):  
T Cells ◽  
Tumor Growth ◽  
Cancer Cell ◽  
Near Infrared ◽  
Single Agent ◽  
T Cell Response ◽  
Host Immunity ◽  
Mouse Tumor ◽  
Syngeneic Mouse ◽  
Interleukin 15

Near infrared photoimmunotherapy (NIR-PIT) is a newly developed and highly selective cancer treatment that employs a monoclonal antibody (mAb) conjugated to a photo-absorber dye, IRDye700DX, which is activated by 690 nm light. Cancer cell-targeted NIR-PIT induces rapid necrotic/immunogenic cell death (ICD) that induces antitumor host immunity including re-priming and proliferation of T cells. Interleukin-15 (IL-15) is a cytokine that activates natural killer (NK)-, B- and T-cells while having minimal effect on regulatory T cells (Tregs) that lack the IL-15 receptor. Here, we hypothesized that IL-15 administration with cancer cell-targeted NIR-PIT could further inhibit tumor growth by increasing antitumor host immunity. Three syngeneic mouse tumor models, MC38-luc, LL/2, and MOC1, underwent combined CD44-targeted NIR-PIT and short-term IL-15 administration with appropriate controls. Comparing with the single-agent therapy, the combination therapy of IL-15 after NIR-PIT inhibited tumor growth, prolonged survival, and increased tumor infiltrating CD8+ T cells more efficiently in tumor-bearing mice. IL-15 appears to enhance the therapeutic effect of cancer-targeted NIR-PIT.

scholarly journals Checkpoint blockade accelerates a novel switch from an NKT-driven TNFα response toward a T cell driven IFN-γ response within the tumor microenvironment

2021 ◽  
Vol 9 (6) ◽  
pp. e002269
Author(s):  
Shota Aoyama ◽  
Ryosuke Nakagawa ◽  
Satoshi Nemoto ◽  
Patricio Perez-Villarroel ◽  
James J Mulé ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Ex Vivo ◽  
T Cell Response ◽  
Effector Function ◽  
Checkpoint Blockade ◽  
Necrosis Factor Alpha ◽  
Ifn Γ

BackgroundThe temporal response to checkpoint blockade (CB) is incompletely understood. Here, we profiled the tumor infiltrating lymphocyte (TIL) landscape in response to combination checkpoint blockade at two distinct timepoints of solid tumor growth.MethodsC57BL/6 mice bearing subcutaneous MC38 tumors were treated with anti-PD-1 and/or anti-CTLA-4 antibodies. At 11 or 21 days, TIL phenotype and effector function were analyzed in excised tumor digests using high parameter flow cytometry. The contributions of major TIL populations toward overall response were then assessed using ex vivo cytotoxicity and in vivo tumor growth assays.ResultsThe distribution and effector function among 37 distinct TIL populations shifted dramatically between early and late MC38 growth. At 11 days, the immune response was dominated by Tumor necrosis factor alpha (TNFα)-producing NKT, representing over half of all TIL. These were accompanied by modest frequencies of natural killer (NK), CD4+, or CD8+ T cells, producing low levels of IFN-γ. At 21 days, NKT populations were reduced to a combined 20% of TIL, giving way to increased NK, CD4+, and CD8+ T cells, with increased IFN-γ production. Treatment with CB accelerated this switch. At day 11, CB reduced NKT to less than 20% of all TIL, downregulated TNFα across NKT and CD4+ T cell populations, increased CD4+ and CD8+ TIL frequencies, and significantly upregulated IFN-γ production. Degranulation was largely associated with NK and NKT TIL. Blockade of H-2kb and/or CD1d during ex vivo cytotoxicity assays revealed NKT has limited direct cytotoxicity against parent MC38. However, forced CD1d overexpression in MC38 cells significantly diminished tumor growth, suggesting NKT TIL exerts indirect control over MC38 growth.ConclusionsDespite an indirect benefit of early NKT activity, CB accelerates a switch from TNFα, NKT-driven immune response toward an IFN-γ driven CD4+/CD8+ T cell response in MC38 tumors. These results uncover a novel NKT/T cell switch that may be a key feature of CB response in CD1d+ tumors.

scholarly journals 843 Development and engineering of human sialidase for degradation of immunosuppressive sialoglycans to treat cancer

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A884-A884
Author(s):  
Li Peng ◽  
Lizhi Cao ◽  
Sujata Nerle ◽  
Robert LeBlanc ◽  
Abhishek Das ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Cells ◽  
First Generation ◽  
Single Agent ◽  
Mouse Tumor ◽  
Cytokine Release ◽  
Tumor Models ◽  
Cell Immunity ◽  
Mouse Tumor Models

BackgroundSialoglycans, a type of glycans with a terminal sialic acid, have emerged as a critical glyco-immune checkpoint that impairs antitumor response by inhibiting innate and adaptive immunity. Upregulation of sialoglycans on tumors has been observed for decades and correlates with poor clinical outcomes across many tumor types. We previously showed that targeted desialylation of tumors using a bifunctional sialidase x antibody molecule, consisting of sialidase and a tumor-associated antigen (TAA)-targeting antibody, has led to robust single-agent efficacy in mouse tumor models. In addition to tumor cells, most immune cells present substantially more abundant sialoglycans than non-hematological healthy cells, which may also contribute to immunosuppression. Therefore, we studied the impact of immune cell desialylation and evaluated the therapeutic potential of a newly developed sialidase-Fc fusion (Bi-Sialidase), which lacks a TAA-targeting moiety and consists of engineered human neuraminidase 2 (Neu2) and human IgG1 Fc region, in preclinical mouse tumor models.MethodsThe first generation Neu2 variant was further optimized to improve titers and stability to constructed Bi-Sialidase. Bi-Sialidase’s desialylation potency and impact on immune responses were studied in vitro using various human immune functional assays, including T-cell activation, allogeneic mixed lymphocyte reaction, antibody-dependent cellular cytotoxicity, macrophages polarization/activation, neutrophil activation, and peripheral blood mononuclear cell (PBMC) cytokine release assays. We evaluated its antitumor efficacy in mouse tumor models. Bi-Sialidase’s safety profile was characterized by conducting rat and non-human primate (NHP) toxicology studies.ResultsThe optimized Bi-Sialidase achieved a titer of 2.5 g/L from a 15-day fed-batch Chinese hamster ovary cell culture; in contrast, the wild-type and first-generation Neu2 had no production or a low titer (<0.1 g/L) under similar conditions, respectively. We demonstrated that Bi-Sialidase led to dose-dependent desialylation of immune cells and potentiated T-cell immunity, without impacting NK, macrophage, or neutrophil activation by desialylating immune cells. Activated and exhausted T cells upregulated surface sialoglycans and Bi-Sialidase-mediated desialylation reinvigorated exhausted-like T cells as measured by IFNg production. Bi-Sialidase treatment also enhanced DC priming and activation of naïve T cells by desialylating both T cells and DCs. Furthermore, Bi-Sialidase showed single-agent antitumor activity in multiple mouse tumor models, including MC38, CT26, A20, and B16F10. Importantly, Bi-Sialidase did not cause cytokine release in human PBMC assays and was tolerated to up to 100 mg/kg in rats and NHPs, demonstrating a wide safety margin.ConclusionsBi-Sialidase with an optimized Neu2 offers a novel immunomodulatory approach to enhancing T-cell immunity by desialylating immunosuppressive sialoglycans for cancer treatment.

scholarly journals 769 A single dose of intratumoral TransCon™ TLR7/8 agonist monotherapy promoted sustained activation of antigen presenting cells resulting in CD4+ and CD8+ T cell activation and tumor growth inhibition

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A804-A804
Author(s):  
Luis Zuniga ◽  
Karan Uppal ◽  
Kathy Bang ◽  
Enping Hong ◽  
Simran Sabharwal ◽  
...  
Keyword(s):  
T Cells ◽  
Tumor Growth ◽  
Growth Inhibition ◽  
Tumor Antigen ◽  
Tumor Growth Inhibition ◽  
Tlr Agonists ◽  
Syngeneic Mouse ◽  
Antigen Presenting ◽  
Anti Tumor Activity ◽  
Dose Dependent

BackgroundThe use of pattern recognition receptor agonists (PRRAs) such as Toll-like receptor (TLR) agonists is an attractive approach for cancer immunotherapy. TLR agonism elicits anti-tumor activity by activating antigen presenting cells (APCs) to promote a proinflammatory microenvironment and anti-tumor immunity. Local delivery of TLR agonists has shown encouraging preclinical and clinical anti-tumor benefit. However, intratumoral (IT) delivery of naked PRRAs may lead to rapid effusion from the tumor microenvironment, potentially impacting their effectiveness in inducing local inflammation and may promote systemic cytokine release, increasing the risk of adverse effects.MethodsTransConTM TLR7/8 Agonist was designed to address the current limitations of PRRA therapies and IT delivery through sustained and controlled release of resiquimod, a potent TLR7/8 agonist, following IT administration of a hydrogel depot.ResultsA single IT injection of TransCon TLR7/8 Agonist induced potent tumor growth inhibition in a dose-dependent manner in syngeneic mouse CT26 tumors. Following IT TransCon TLR7/8 Agonist treatment, acute and sustained upregulation of cell surface markers indicative of activation of APCs, such as CD54, CD69, and CD86, in the tumor was observed by fluorescence activated flow cytometry (FACs). Additionally, TransCon TLR7/8 Agonist treatment was associated with an increase in the frequency of APCs with an activated phenotype in tumor draining lymph nodes (LNs). Further, a concomitant potentiation in the frequency of activated CD4 and CD8 T cells in tumor draining LNs following IT TransCon TLR7/8 Agonist treatment was observed, as demonstrated by increased expression of Ki67, ICOS, or granzyme B.ConclusionsThese data support that a single IT dose of TransCon TLR7/8 Agonist can mediate robust anti-tumor activity as a monotherapy in the CT26 syngeneic mouse tumor model while promoting local activation of intratumoral APCs. Such activation may promote tumor antigen uptake and migration to tumor-associated lymphoid tissue, as evidenced by an increase in APCs with an activated phenotype in tumor draining LNs following TransCon TLR7/8 Agonist treatment. Activated tumor antigen-bearing APCs can promote the priming and activation of tumor-specific T cells in the tumor-draining LNs. Consistently, a dose-dependent increase in the frequency of T cells with an activated effector phenotype in tumor draining LNs following administration of TransCon TLR7/8 Agonist was observed. These preclinical data further support TransCon TLR7/8 Agonist as a novel and potentially efficacious PRRA therapy. A clinical trial to evaluate safety and efficacy of TransCon TLR7/8 Agonist as monotherapy, and in combination with pembrolizumab, in cancer patients has been initiated (transcendIT-101; NCT04799054).Ethics ApprovalThe animal studies performed described were performed in accordance with the “Guide for the Care and Use of Laboratory Animals: Eighth Edition” and approved by the institutional animal care and use committee (IACUC).

scholarly journals Peptide vaccination directed against IDO1-expressing immune cells elicits CD8+ and CD4+ T-cell-mediated antitumor immunity and enhanced anti-PD1 responses

2020 ◽  
Vol 8 (2) ◽  
pp. e000605
Author(s):  
Souvik Dey ◽  
Erika Sutanto-Ward ◽  
Katharina L Kopp ◽  
James DuHadaway ◽  
Arpita Mondal ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Mhc Class I ◽  
Adoptive Transfer ◽  
Immune Cells ◽  
Class Ii ◽  
T Cell Response ◽  
Class I ◽  
Antitumor Effects

BackgroundThe tryptophan-catabolizing enzyme indoleamine 2,3-dioxygenase 1 (IDO1), which subverts T-cell immunity at multiple levels, is itself subject to inherent T-cell reactivity. This intriguing deviation from central tolerance has been interpreted as counterbalancing IDO1-mediated immunosuppression. Based on this hypothesis, clinical studies employing an IDO1 peptide-based vaccine approach for cancer treatment have been initiated, but there remains a pressing need to further investigate the immunological ramifications of stimulating the anti-IDO1 T-cell response in this manner.MethodsCT26 colon carcinoma tumors were evaluated for expression of IDO1 protein by western blot analysis, immunofluorescence microscopy and flow cytometry. Mouse IDO1-derived peptides, predicted to bind either major histocompatibility complex (MHC) class I or II of the H2d BALB/c strain, were emulsified in 50% Montanide for prophylactic or therapeutic vaccine treatment of CT26 tumor-bearing mice initiated either 7 days prior to or following tumor cell injection, respectively. In some therapeutic treatment experiments, administration of programmed cell death protein 1-binding antibody (anti-PD1 antibody) or epacadostat was concurrently initiated. Tumor size was determined by caliper measurements and comparative tumor growth suppression was assessed by longitudinal analyses of tumor growth data. For adoptive transfer, T cells from complete responder animals were isolated using paramagnetic beads and fluorescence-activated cell sorting.ResultsThis study identifies mouse MHC class I-directed and II-directed, IDO1-derived peptides capable of eliciting antitumor responses, despite finding IDO1 expressed exclusively in tumor-infiltrating immune cells. Treatment of established tumors with anti-PD1 antibody and class I-directed but not class II-directed IDO1 peptide vaccines produced an enhanced antitumor response. Likewise, class I-directed and II-directed IDO1 peptides elicited an enhanced combinatorial response, suggesting distinct mechanisms of action. Consistent with this interpretation, adoptive transfer of isolated CD8+ T cells from class I and CD4+ T cells from class II peptide-vaccinated responder mice delayed tumor growth. The class II-directed response was completely IDO1-dependent while the class I-directed response included an IDO1-independent component consistent with antigen spread.ConclusionsThe in vivo antitumor effects demonstrated with IDO1-based vaccines via targeting of the tumor microenvironment highlight the utility of mouse models for further exploration and refinement of this novel vaccine-based approach to IDO1-directed cancer therapy and its potential to improve patient response rates to anti-PD1 therapy.

scholarly journals Interleukin 1-induced, T cell-mediated regression of immunogenic murine tumors. Requirement for an adequate level of already acquired host concomitant immunity.

1988 ◽  
Vol 168 (6) ◽  
pp. 2031-2043 ◽  
Author(s):  
R J North ◽  
R H Neubauer ◽  
J J Huang ◽  
R C Newton ◽  
S E Loveless
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Tumor Regression ◽  
Interleukin 1 ◽  
Host Immunity ◽  
Antitumor Action ◽  
Complete Regression ◽  
Subtherapeutic Level

Intraperitoneal injection of human rIL-1 in a dose of 0.5 microgram daily for 5 d, or 1 microgram daily for 3 d, was capable of causing complete regression of immunogenic SA1 sarcoma growing subcutaneously in syngeneic or semisyngeneic mice. Higher doses of IL-1 were not more therapeutic against the SA1 sarcoma, but needed to be given to cause complete regression of the immunogenic L5178Y lymphoma. On the other hand, the P815 mastocytoma was much less responsive to IL-1 therapy, in that it failed to undergo complete regression in response to doses of IL-1 capable of causing regression of the L5178Y lymphoma. IL-1 caused regression of the SA1 sarcoma when given on days 6-8 of tumor growth, but not when given on days 1-3. This refractoriness of a small tumor to IL-1 therapy suggests that the antitumor action of IL-1 is based on an underlying host-immune response that is not generated until after day 3 of tumor growth. Direct evidence for the participation of host immunity in IL-1-induced tumor regression was supplied by results showing that IL-1 was not therapeutic against the SA1 sarcoma growing in T cell-deficient (TXB) mice, unless these mice were first infused with Ly-2+ and L3T4+ T cells from donor mice bearing an established SA1 sarcoma. In contrast, normal T cells, or T cells from donor mice bearing a YAC-1 lymphoma, failed to provide TXB recipients with the ability to cause regression of their SA-1 sarcoma in response to IL-1 treatment. The results are in keeping with the interpretation that exogenous IL-1, by augmenting the production of tumor-sensitized T cells, converts a subtherapeutic level of host immunity to a therapeutic level. The results suggest, in addition, that IL-1 only stimulates the replication of T cells that are already engaged in the antitumor immune response.

Effect of MMP9 inhibition on effector T-cell responses in a PD1-axis refractory model.

2017 ◽  
Vol 35 (7_suppl) ◽  
pp. 104-104
Author(s):  
Victoria Smith ◽  
Vladi Juric ◽  
Amanda Mikels-Vigdal ◽  
Chris O'Sullivan ◽  
Maria Kovalenko ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Cell Activation ◽  
Immune Cell ◽  
Single Agent ◽  
Fold Increase ◽  
Cytotoxic T Cell

104 Background: Matrix metalloproteinase 9 (MMP9) acts via diverse mechanisms to promote tumor growth and metastasis, and is a key component of the immune-suppressive myeloid inflammatory milieu. We developed a monoclonal antibody (AB0046) that inhibits murine MMP9 and assessed its mechanism of action in immunocompetent mice as a single agent, or in combination with a murine anti-PDL1 antibody. Methods: An orthotopic, syngeneic tumor model (NeuT), which models MMP9-positive myeloid infiltrate, was utilized for efficacy and pharmacodynamic studies involving RNA and T cell receptor (TCR) sequencing, and flow cytometry. Enzymatic analyses were performed on T cell chemoattractant CXCR3 ligands (CXCL9, CXCL10, and CXCL11) which were subsequently evaluated in chemotaxis assays. Results: Anti-MMP9 treatment alone or in combination with an anti-PDL1 antibody decreased primary tumor growth as compared to IgG control-treated animals (56% vs 335% tumor growth increase, p = 0.0005) or anti-PDL1 alone. Profiling of tumors by RNA sequencing revealed that inhibition of MMP9 resulted in elevated expression of genes associated with immune cell activation pathways (Hallmark Interferon Gamma Response, FDR p < 0.001). Treatment with anti-MMP9 and anti-PDL1 antibodies decreased TCR clonality, with evidence of a more diverse TCR repertoire (p = 0.005). Immunophenotyping of tumor-associated T cells by flow cytometry showed that anti-MMP9 and anti-PDL1 co-treatment promoted a 2.8-fold increase in CD3+ cells in tumors (p = 0.01), which was associated with an increase in CD4+ T cells (3.2-fold increase; p = 0.006) and CD8+ T cells (2.8-fold increase; p = 0.013). In contrast, anti-MMP9 and combination treatment resulted in a decrease in tumor-associated regulatory T cells (CD25+ FoxP3+ cells, p = 0.04). MMP9 cleavage of T cell chemoattractant ligands in vitro rendered them functionally inactive for recruitment of activated primary human effector T cells. Conclusions: Inhibition of MMP9 reduces tumor burden and promotes cytotoxic T cell infiltration in a PD1-axis refractory mouse model. The combination of nivolumab and GS-5745, a humanized anti-MMP9 inhibitory antibody, is currently being evaluated in gastric cancer (NCT02864381).

scholarly journals 884 Engineered toxin body mediated depletion of TIGIT expressing immune cells for cancer immunotherapy

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A926-A926
Author(s):  
Elizabeth Saputra ◽  
Garrett Cornelison ◽  
Jennifer Mitchell ◽  
Karia Williams ◽  
Andrea Mendiola ◽  
...  
Keyword(s):  
T Cells ◽  
Immune Cells ◽  
Immune Cell ◽  
Single Agent ◽  
Antibody Fragment ◽  
Cell Surface Receptor ◽  
Mouse Tumor ◽  
List Type ◽  
Proof Of Concept

BackgroundTIGIT (T cell immunoreceptor with Ig and ITIM domains) is an exciting novel target for immuno-oncology which functions as an immune checkpoint on multiple immune cell types including memory CD8+, CD4+ Treg, and memory CD4+ cells. TIGIT upregulation on tumor infiltrating lymphocytes (TILs) has been observed in multiple cancer types and contributes to an immunosuppressive tumor microenvironment (TME). Interestingly, TIGIT is commonly co-expressed with PD-1 on Tregs in the TME, tumor antigen specific CD8+ T cells and CD8+ TILs, leading to weakened anti-tumor immune responses.1–2 To date, TIGIT inhibiting monoclonal antibodies (mAb) have shown little activity as a monotherapy in clinical and preclinical studies. 3–4 Therefore, current clinical trials are now focused on combining TIGIT mAbs with known commercial PD-1 or PD-L1 mAbs. A TIGIT-specific engineered toxin body (ETB) represents a wholly new approach to targeting TIGIT expressing cells including those co-expressing TIGIT and PD-1.MethodsETBs targeting TIGIT were designed to deplete TIGIT-expressing TILs, including Tregs, directly in the TME. ETBs are proteins that consist of an antibody fragment genetically fused to a proprietary de-immunized (DI) form of the Shiga-like toxin A subunit (SLTA). These proteins are specific for a cell surface receptor, and function through triggering rapid internalization upon binding, followed by an enzymatic and irreversible termination of ribosomal protein synthesis resulting in cellular apoptosis. Here we provide proof of concept for ETBs as a novel modality for the depletion of TIGIT-expressing immune cells.ResultsTIGIT-targeting ETBs exhibit potent in vitro cytotoxicity of TIGIT over-expressing cell lines (IC50<1nM). These ETBs also lead to apoptotic depletion of ex vivo TIGIT-expressing regulatory T cells (Tregs) from healthy donors. In mixed culture assays, TIGIT ETBs increase the proliferation of TIGIT negative T cells by depleting TIGIT-expressing T cells.ConclusionsStudies to assess pharmacodynamics and efficacy of TIGIT targeting ETBs using a double knock-in (TIGIT and PD-1) mouse tumor model are ongoing, but these early proof of concept in vitro data support the hypothesis that ETBs can deplete TIGIT positive immune cell populations including those co-expressing PD-1. It is possible that targeted TIGIT inhibition through ETB-induced cell death could tip the balance towards tumor regression by eliminating this novel checkpoint (and TIGIT/PD-1 co-expression) at the level of the TME.ReferencesJinhua X, Ji W, Shouliang C, Liangfeng Z. Expression of immune checkpoints in T cells of esophageal cancer patients. Oncotarget 2016;7(39):1–10.Blessin NC, Simon R, Kluth M, Fischer K, et al. Patterns of TIGIT expression in lymphatic tissue, inflammation and cancer. Dis Markers 2019;2019:1–13.Johnston RJ, Comps-Agrar L, Hackney J, Yu X, et al. The immunoreceptor TIGIT regulates anti-tumor and antiviral CD8(+) T effector function. Cancer Cell 2014;26(6):923–927.Bendell JC, Bedrad P, Bang Y-J, LoRusso P, et al. Phase Ia/Ib dose-escalation study of the anti-TIGIT antibody Tiragolumab as a single agent and in combination with atezolizumab in patients with advanced solid tumors. Proceedings: AACR Annual Meeting 2020; April 27–28, 2020 and June 22–24, 2020; Philadelphia, PA.

scholarly journals VLM catecholaminergic neurons control tumor growth by regulating CD8+ T cells

2021 ◽  
Vol 118 (28) ◽  
pp. e2103505118
Author(s):  
Ze Zhang ◽  
Yehua Li ◽  
Xueyuan Lv ◽  
Linlin Zhao ◽  
Xiaodong Wang
Keyword(s):  
T Cells ◽  
Nervous System ◽  
Tumor Growth ◽  
Mouse Brain ◽  
Adaptive Immune System ◽  
Ventrolateral Medulla ◽  
Mouse Tumor ◽  
Control Tumor Growth ◽  
The Central Nervous System ◽  
Control Tumor

It is known that tumor growth can be influenced by the nervous system. It is not known, however, if tumors communicate directly with the central nervous system (CNS) or if such interactions may impact tumor growth. Here, we report that ventrolateral medulla (VLM) catecholaminergic (CA) neurons in the mouse brain are activated in tumor-bearing mice and the activity of these neurons significantly alter tumor growth in multiple syngeneic and spontaneous mouse tumor models. Specific ablation of VLM CA neurons by a dopamine-β-hydroxylase (DBH) promotor-activated apoptosis-promoting caspase-3 in Dbh-Cre mice as well as inhibition of these neurons by a chemogenetic method slowed tumor progression. Consistently, chemogenetic activation of VLM CA neurons promoted tumor growth. The tumor inhibition effect of VLM CA neuron ablation is mitigated in Dbh-Cre;Rag1−/− mice, indicating that this regulatory effect is mediated by the adaptive immune system. Specific depletion of CD8+ T cells using an anti-CD8+ antibody also mitigated the tumor suppression resulting from the VLM CA neuron ablation. Finally, we showed that the VLM CA neuronal ablation had an additive antitumor effect with paclitaxel treatment. Collectively, our study uncovered the role of VLM CA neurons in the mouse brain in controlling tumor growth in the mouse body.

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