Retraction: Targeting Neural-Restrictive Silencer Factor Sensitizes Tumor Cells to Antibody-Based Cancer Immunotherapy In Vitro via Multiple Mechanisms

Aims and Background Dendritic cell (DC)-tumor fusion hybrid vaccinees that facilitate antigen presentation represent a novel powerful strategy in cancer immunotherapy. Preclinical studies have demonstrated that IL-12 promotes specific antitumor immunity mediated by T cells in several types of tumors. In the present study, we investigated the antitumor immunity derived from vaccination of fusion hybrids between DCs and engineered J558/IL-12 myeloma cells secreting Th1 cytokine IL-12. Methods The expression vector pcDNA-IL-12 was generated and transfected into J558 myeloma cells and then bone marrow-derived DCs were fused with engineered J558/IL-12 cells. The antitumor immunity derived from vaccination of the fusion hybrid DC/J558/IL-12 was evaluated in vitro and in vivo. Results DC/J558/IL-12 cells secreted recombinant IL-12 (1.6 ng/mL), and inoculation of BALB/c mice with DC/J558/IL-12 hybrid induced a Th1 dominant immune response and resulted in tumor regression. Immunization of mice with engineered DC/J558/IL-12 hybrid elicited stronger J558 tumor-specific cytotoxic T lymphocyte (CTL) responses in vitro as well as more potent protective immunity against J558 tumor challenge in vivo than immunization with the mixture of DCs and J558/IL-12, J558/IL-12 and J558, respectively. Furthermore, the antitumor immunity mediated by DC/J558/1L-12 tumor cell vaccination in vivo appeared to be dependent on CD8+ CTL. Conclusions These results demonstrate that the engineered fusion hybrid vaccines that combine Th1 cytokine gene-modified tumor cells with DCs may be an attractive strategy for cancer immunotherapy.

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Antibody:CD47 ratio regulates macrophage phagocytosis through competitive receptor phosphorylation

10.1101/2020.07.31.231779 ◽

2020 ◽

Cited By ~ 1

Author(s):

Emily C. Suter ◽

Eva M. Schmid ◽

Erik Voets ◽

Brian Francica ◽

Daniel A. Fletcher

Keyword(s):

Immune Responses ◽

Cancer Immunotherapy ◽

Tumor Cells ◽

Effector Function ◽

Fc Gamma Receptors ◽

Chimeric Receptors ◽

Macrophage Phagocytosis ◽

Cancer Immunotherapies ◽

Blocking Antibodies

ABSTRACTCancer immunotherapies often modulate macrophage effector function by introducing either targeting antibodies that activate Fc gamma receptors or blocking antibodies that disrupt inhibitory SIRPα-CD47 engagement. Yet how these competing signals are integrated is poorly understood mechanistically, raising questions about how to effectively titrate immune responses. Here we find that macrophage phagocytic decisions are regulated by the ratio of activating ligand to inhibitory ligand on targets over a broad range of absolute molecular densities. Using endogenous as well as chimeric receptors, we show that activating:inhibitory ligand ratios of at least 10:1 are required to promote phagocytosis of model antibody-opsonized CD47-inhibited targets and that lowering this ratio reduces FcγR phosphorylation due to inhibitory phosphatases recruited to CD47-bound SIRPα. We demonstrate that ratiometric signaling is critical for phagocytosis of tumor cells and can be modified by blocking SIRPα in vitro, indicating that balancing targeting and blocking antibodies may be important for controlling macrophage phagocytosis in cancer immunotherapy.

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693 APX601, a Novel TNFR2 antagonist antibody for cancer immunotherapy

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2020-sitc2020.0693 ◽

2020 ◽

Vol 8 (Suppl 3) ◽

pp. A735-A735

Author(s):

Erin Filbert ◽

Sushma Krishnan ◽

Ryan Alvarado ◽

George Huang ◽

Francis Bahjat ◽

...

Keyword(s):

Cancer Immunotherapy ◽

Tumor Cells ◽

Immune Suppression ◽

Xenograft Model ◽

Mechanisms Of Action ◽

Healthy Human ◽

Immunosuppressive Cell ◽

Promising Therapeutic Approach ◽

Tnf Α

BackgroundA key barrier to effective immunotherapy for cancer is the immunosuppressive tumor microenvironment (TME) characterized by infiltrating regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSC). While depletion of immune-suppressive cells is a promising cancer immunotherapy strategy, current approaches are ineffective due to lack of specificity and safety concerns. Tumor Necrosis Factor Receptor 2 (TNFR2) is emerging as a novel, selective target to overcome immunosuppression in TME. TNFR2 expression is generally restricted to highly immunosuppressive cell populations in the TME and the TNFR2-TNF-α pathway plays an important role in the generation and survival of these cells. TNFR2 is also an oncogene upregulated on certain tumors and can enhance tumor cell survival. Thus, targeting TNFR2 is a promising therapeutic approach with multiple potential mechanisms of action.MethodsA diverse panel of antibodies to TNFR2 was created using APXiMAB™, Apexigen’s proprietary rabbit monoclonal antibody technology. A robust assessment of over 100 antibody candidates for TNFR2 binding, TNF-α blockade and functional assays yielded APX601, a humanized IgG1 antibody, as the lead therapeutic candidate. The ability of APX601 to reverse immune suppression was assessed in Treg and MDSC suppression assays. In addition, the ability of APX601 to deplete TNFR2-expressing Treg and tumor cells was assessed both in vitro and in vivo using the mouse Colo205 xenograft model.ResultsAPX601 binds specifically to human TNFR2 with high affinity (Kd = 47 pM) and recognizes a unique epitope in the CRD1 domain of TNFR2. APX601 is a potent antagonist that blocks the TNFR2-TNF-α interaction in cell-based ligand binding assays (IC50 = 0.149 nM). APX601 is capable of reversing immune suppression via two mechanisms: 1) significant blockade of the immunosuppressive functions of both Tregs and MDSCs by inhibiting the binding of TNFR2 to its ligand TNF-α and 2) depletion of TNFR2-expressing Tregs, MDSC and tumor cells via antibody-dependent cell cytotoxicity (ADCC) (EC50 = 1.14 nM) and ADCP (EC50 = 0.71 nM) effector functions.ConclusionsAPX601 is a potent TNFR2 antagonist antibody that reverses immune suppression by targeting TNFR2-expressing Treg and MDSC, and induces killing of tumor cells. Our data support the further development of APX601, a promising immunotherapeutic antibody with multiple potential mechanisms of action, for the treatment of a variety of solid tumors.Ethics ApprovalHealthy human blood samples were obtained from Stanford Blood Center (Palo Alto, CA) from consenting donors under an approved protocol.

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CBLB ablation with CRISPR/Cas9 enhances cytotoxicity of human placental stem cell-derived NK cells for cancer immunotherapy

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2020-001975 ◽

2021 ◽

Vol 9 (3) ◽

pp. e001975

Author(s):

Xuan Guo ◽

Tanel Mahlakõiv ◽

Qian Ye ◽

Srinivas Somanchi ◽

Shuyang He ◽

...

Keyword(s):

Antitumor Activity ◽

Nk Cells ◽

Cancer Immunotherapy ◽

Tumor Cells ◽

Nk Cell ◽

Cell Activity ◽

Negative Regulator ◽

Hematopoietic Stem ◽

Nsg Mice

BackgroundTumors often develop resistance to surveillance by endogenous immune cells, which include natural killer (NK) cells. Ex vivo activated and/or expanded NK cells demonstrate cytotoxicity against various tumor cells and are promising therapeutics for adoptive cancer immunotherapy. Genetic modification can further enhance NK effector cell activity or activation sensitization. Here, we evaluated the effect of the genetic deletion of ubiquitin ligase Casitas B-lineage lymphoma pro-oncogene-b (CBLB), a negative regulator of lymphocyte activity, on placental CD34+ cell-derived NK (PNK) cell cytotoxicity against tumor cells.MethodsUsing CRISPR/Cas9 technology, CBLB was knocked out in placenta-derived CD34+ hematopoietic stem cells, followed by differentiation into PNK cells. Cell expansion, phenotype and cytotoxicity against tumor cells were characterized in vitro. The antitumor efficacy of CBLB knockout (KO) PNK cells was tested in an acute myeloid leukemia (HL-60) tumor model in NOD-scid IL2R gammanull (NSG) mice. PNK cell persistence, biodistribution, proliferation, phenotype and antitumor activity were evaluated.Results94% of CBLB KO efficacy was achieved using CRISPR/Cas9 gene editing technology. CBLB KO placental CD34+ cells differentiated into PNK cells with high cell yield and >90% purity determined by CD56+ CD3− cell identity. Ablation of CBLB did not impact cell proliferation, NK cell differentiation or phenotypical characteristics of PNK cells. When compared with the unmodified PNK control, CBLB KO PNK cells exhibited higher cytotoxicity against a range of liquid and solid tumor cell lines in vitro. On infusion into busulfan-conditioned NSG mice, CBLB KO PNK cells showed in vivo proliferation and maturation as evidenced by increased expression of CD16, killer Ig-like receptors and NKG2A over 3 weeks. Additionally, CBLB KO PNK cells showed greater antitumor activity in a disseminated HL60-luciferase mouse model compared with unmodified PNK cells.ConclusionCBLB ablation increased PNK cell effector function and proliferative capacity compared with non-modified PNK cells. These data suggest that targeting CBLB may offer therapeutic advantages via enhancing antitumor activities of NK cell therapies.

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Targeting Neural-Restrictive Silencer Factor Sensitizes Tumor Cells to Antibody-Based Cancer Immunotherapy In Vitro via Multiple Mechanisms

The Journal of Immunology ◽

10.4049/jimmunol.1000045 ◽

2010 ◽

Vol 184 (11) ◽

pp. 6035-6042 ◽

Cited By ~ 4

Author(s):

Martin V. Kolev ◽

Marieta M. Ruseva ◽

B. Paul Morgan ◽

Rossen M. Donev

Keyword(s):

Cancer Immunotherapy ◽

Tumor Cells

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In vitro and in vivo suppression of growth of rat liver epithelial tumor cells by antisense oligonucleotide against protein kinase C-alpha

Journal of Hepatology ◽

10.1034/j.1600-0641.2000.033004601.x ◽

2000 ◽

Vol 33 (4) ◽

pp. 601-608 ◽

Cited By ~ 8

Author(s):

Shwu-Bin Lin ◽

Li-Ching Wu ◽

Siao-Ling Huang ◽

Hui-Lun Hsu ◽

Sung-Hwa Hsieh ◽

...

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Tumor Cells ◽

Rat Liver ◽

Antisense Oligonucleotide ◽

Epithelial Tumor ◽

Kinase C ◽

Epithelial Tumor Cells

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Melatonin modifies tumor hypoxia and metabolism by inhibiting HIF-1α and energy metabolic pathway in the in vitro and in vivo models of breast cancer

Melatonin Research ◽

10.32794/mr11250042 ◽

2019 ◽

Vol 2 (4) ◽

pp. 83-98 ◽

Cited By ~ 2

Author(s):

André De Lima Mota ◽

Bruna Vitorasso Jardim-Perassi ◽

Tialfi Bergamin De Castro ◽

Jucimara Colombo ◽

Nathália Martins Sonehara ◽

...

Keyword(s):

Breast Cancer ◽

Glucose Metabolism ◽

Tumor Growth ◽

Tumor Cells ◽

Carbonic Anhydrases ◽

In Vivo Models ◽

Ca Ix ◽

Gene And Protein Expression

Breast cancer is the most common cancer among women and has a high mortality rate. Adverse conditions in the tumor microenvironment, such as hypoxia and acidosis, may exert selective pressure on the tumor, selecting subpopulations of tumor cells with advantages for survival in this environment. In this context, therapeutic agents that can modify these conditions, and consequently the intratumoral heterogeneity need to be explored. Melatonin, in addition to its physiological effects, exhibits important anti-tumor actions which may associate with modification of hypoxia and Warburg effect. In this study, we have evaluated the action of melatonin on tumor growth and tumor metabolism by different markers of hypoxia and glucose metabolism (HIF-1α, glucose transporters GLUT1 and GLUT3 and carbonic anhydrases CA-IX and CA-XII) in triple negative breast cancer model. In an in vitro study, gene and protein expressions of these markers were evaluated by quantitative real-time PCR and immunocytochemistry, respectively. The effects of melatonin were also tested in a MDA-MB-231 xenograft animal model. Results showed that melatonin treatment reduced the viability of MDA-MB-231 cells and tumor growth in Balb/c nude mice (p <0.05). The treatment significantly decreased HIF-1α gene and protein expression concomitantly with the expression of GLUT1, GLUT3, CA-IX and CA-XII (p <0.05). These results strongly suggest that melatonin down-regulates HIF-1α expression and regulates glucose metabolism in breast tumor cells, therefore, controlling hypoxia and tumor progression.

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