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.

MDNA11 is a long-acting IL-2 superkine that potentiates durable immune response in mouse tumor models and non-human primates.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. e14546-e14546
Author(s):  
Minh D. To ◽  
Fahar Merchant ◽  
Nina Merchant
Keyword(s):  
T Cells ◽  
Cd8 T Cells ◽  
Cell Activation ◽  
Single Agent ◽  
Mouse Tumor ◽  
Tumor Models ◽  
Toxicology Study ◽  
Long Acting ◽  
Mouse Tumor Models

e14546 Background: The efficacy and safety of recombinant human IL-2 (rhIL-2; Proleukin) to treat certain cancers is limited by a short half-life, marked toxicity and selective high affinity binding to IL2Ra over IL2Rb, resulting in preferential activation of suppressive Tregs. In contrast, MDNA11 has been engineered as a long-acting IL-2 superkine with high affinity IL2Rb receptor selectivity, resulting in preferential anti-cancer effector immune cell activation. Methods: MDNA11 was characterized in both in vitro and in vivo studies including assessment of receptor binding kinetics using BLI/Octet, receptor-mediated signaling in human PMBCs, efficacy in syngeneic mouse tumor models including memory response, as well as safety and PK/PD assessments in non-human primates (NHP). Results: Unlike rhIL-2, MDNA11 does not bind to human IL2Ra but demonstrates a 30-fold higher affinity binding to human IL2Rb. This selectivity resulted in enhanced in vitro STAT5 signaling in human NK and resting CD8 T cells with diminished signaling in Tregs; validation studies in humanized mice are ongoing. In CT26 and MC38 syngeneic tumor models, MDNA11 demonstrates potent and durable efficacy as monotherapy following a Q1W dose schedule for 2 weeks. Synergy with anti-PD1 and anti-CTLA4 immune checkpoint inhibitors (ICIs) was observed and a robust immune memory response developed in all mice with complete tumor clearance. These mice were protected against relapse and tumor re-challenges for up to 8 months without any further treatment, and showed the presence of antigen-specific CD8 T cells. In binding studies with IL-2 receptors of different species, MDNA11 showed highly similar affinity towards human and cynomolgus IL2Rb, confirming the latter as a highly relevant model for toxicology study. MDNA11 was well tolerated in cynomolgus monkeys up to 0.6 mg/kg, while inducing durable (≥10 days) proliferation and expansion of NK and CD8 T cells. Effects on Tregs were minimal and there was no eosinophilia and hypotension (associated with vascular leak syndrome). At high doses of MDNA11, the most common clinical observations were transient loss of appetite and diarrhea. There was modest increase in levels of IFNg and TNFa, but no sign of cytokine release syndrome. Dosing did not trigger development of anti-drug antibodies or histopathologic evidence of pulmonary edema (a major IL-2 induced toxicity). Conclusions: MDNA11 is a long-acting IL-2 superkine that exhibits robust efficacy in mouse tumor models as a single agent and was synergistic in combination with ICIs (anti-CTLA4 and anti-PD1). In NHP, MDNA11 demonstrates selective immune effector cell activation and a favorable safety profile. These data constitute a strong framework for the design of a pivotal GLP toxicology study to further support the planned clinical study of MDNA11 either as a single agent or in combination with ICIs.

Role of the immunoglobulin constant region in the antitumor activity of antibodies to cytotoxic T-lymphocyte antigen-4 (CTLA-4).

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 9055-9055
Author(s):  
Alan J. Korman ◽  
John Engelhardt ◽  
Vafa Shahabi ◽  
Roumyana Yordanova ◽  
Karla Henning ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Antitumor Activity ◽  
Phase Iii ◽  
Mouse Tumor ◽  
Constant Region ◽  
Tumor Site ◽  
Tumor Models ◽  
Mouse Tumor Models

9055 Background: Anti-CTLA-4 therapy enhances antitumor T-cell responses by both cell-intrinsic and cell-extrinsic mechanisms. Effector T-cell (Teff) activation is increased directly by interfering with CTLA-4-B7 interactions that negatively regulate T cells and by interfering with CTLA-4 expressed on regulatory T cells (Tregs), which function to inhibit immune responses. To analyze in greater detail the mechanism of action of anti-CTLA-4 antibodies (Abs), we examined the role of the immunoglobulin constant region in the antitumor activity of anti-CTLA-4 Abs in mouse tumor models. Methods: The activity of anti-CTLA-4 Abs with different mouse IgG constant regions were compared in several mouse tumor models, and intratumoral and peripheral T cells were analyzed by FACS. DNA samples from 488 patients with metastatic melanoma who received ipilimumab in a phase III clinical trial, MDX010-20, were analyzed for polymorphisms in the IgG fragment c receptor (FcR) at FCGR3A (V158F) and FCGR2A (H131R) loci. Results: In subcutaneous MC38 and CT26 colon tumor models, an anti-CTLA-4 Ab containing the mouse IgG2a constant region exhibited enhanced antitumor activity compared to an anti-CTLA-4 Ab containing the IgG2b constant region, while anti-CTLA-4 Abs containing mouse IgG1 or a mutated mouse IgG1 D265A constant region showed no activity. Anti-CTLA-4-IgG2a caused a dramatic reduction of Tregs at the tumor site that resulted in a greater Teff/Treg ratio. In contrast, all isotypes resulted in expansion of Tregs in the periphery. These results point to an important role for FcR in the action of anti-CTLA-4 Abs. In patients from study MDX010-20, there was no association between the 2 FcR polymorphisms (FCGR3A and FCGR2A) and overall survival. Conclusions: These preclinical studies reveal a novel dual activity of anti-CTLA-4 Abs consisting of intratumoral reduction of Tregs together with activation of Teff cells. This effect is mediated by the constant region and is presumably due to antibody-dependent cellular cytotoxicity. The data suggest that FcR-bearing cells at the tumor site, as well as the presence of intratumoral Tregs, may be important factors in the antitumor activity of anti-CTLA-4 Abs.

scholarly journals 708 Novel ways to exploit IL-21 to augment adoptive T cell transfer therapy against tumors

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A737-A737
Author(s):  
Anna Cole ◽  
Guillermo Rangel RIvera ◽  
Aubrey Smith ◽  
Megan Wyatt ◽  
Brandon Ware ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Immune Cells ◽  
Striking Difference ◽  
T Cell Therapy ◽  
Cell Immunity ◽  
Emory University

BackgroundIL-21 enhances the anti-tumor capacity of adoptively transferred CD8+ T cells, while IL-2 and IL-15 impair T cell immunity by driving their expansion to a more differentiated status. Yet, these cytokines can act on many different immune cells. Given the potency of IL-21, we tested if this cytokine directly augments T cells or rather if it enhances other immune cells in the culture that indirectly improves T cell therapy.MethodsTo test this question, splenocytes from pmel-1 transgenic mice were used, as all CD8+ T cells express a transgenic TCR specific for tumor-antigen gp10025–33 overexpressed on melanoma. We then peptide activated naïve CD8+ T cells enriched or not from the spleen of pmel-1 mice and expanded them in the presence of IL-21 or IL-2 (10 ng/mL) for four days. Expanded pmel-1 from these various cultures were then restimulated with irradiated splenocytes pulsed with gp10025–33 and grown an additional seven days with IL-2 (10 ng/mL), irrespective of their initial cytokine condition. The in vitro memory phenotype, exhaustion profile, and cytokine secretion of these cultures were then assayed. Furthermore, mice bearing B16KVP melanoma tumors were infused with pmel-1 T cells expanded via these various approaches and compared for their relative capacity to engraft, persist, and regress tumor in vivo.ResultsInterestingly, we discovered that IL-21-treated T cells generated from bulk splenocytes are phenotypically and functionally distinct from IL-21-treated isolated T cells. Upon restimulation, IL-21-treated T cells from bulk splenocytes exhibited an exhausted phenotype that was like anergic IL-2-treated T cells. Moreover, few cells expressed CD62L but expressed heightened markers of suppression, including TIM3, PD-1, and EOMES. Moreover, they produced more effector molecules, including granzyme B and IFN-gamma. In vivo IL-21-treated T cells expanded from bulk splenocytes engrafted and persisted poorly, in turn mediating suboptimal regression of melanoma. Conversely, IL-21 dramatically bolstered the engraftment and antitumor activity of T cells only if they were first isolated from the spleen prior to their expansion and infusion into the animal.ConclusionsCollectively, our data shows that IL-21 may improve ACT therapy best when used directly on antitumor CD8+ T cells. Further studies will illuminate the mechanism behind this striking difference and determine whether other cell subsets reactive to IL-21 cause T cell dysfunction and/or reduced bioavailability. These findings are important for defining the best culture conditions in which to use IL-21 for ACT.AcknowledgementsWe would like to acknowledge Emory University, The Winship Cancer Institute, and the Pediatrics/Winship Flow Cytometry Core.Ethics ApprovalAll animal procedures were approved by the Institutional Animal Care and Use Committee of Emory University, protocol number 201900225.

scholarly journals Nicotinamide combined with gemcitabine is an immunomodulatory therapy that restrains pancreatic cancer in mice

2020 ◽  
Vol 8 (2) ◽  
pp. e001250
Author(s):  
Benson Chellakkan Selvanesan ◽  
Kiran Meena ◽  
Amanda Beck ◽  
Lydie Meheus ◽  
Olaya Lara ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Immune Cells ◽  
Mouse Tumor ◽  
Epitope Spreading ◽  
Stromal Compartment ◽  
Positive Effects

BackgroundTreatments for pancreatic ductal adenocarcinoma are poorly effective, at least partly due to the tumor’s immune-suppressive stromal compartment. New evidence of positive effects on immune responses in the tumor microenvironment (TME), compelled us to test the combination of gemcitabine (GEM), a standard chemotherapeutic for pancreatic cancer, with nicotinamide (NAM), the amide form of niacin (vitamin B3), in mice with pancreatic cancer.MethodsVarious mouse tumor models of pancreatic cancer, that is, orthotopic Panc-02 and KPC (KrasG12D, p53R172H, Pdx1-Cre) grafts, were treated alternately with NAM and GEM for 2 weeks, and the effects on efficacy, survival, stromal architecture and tumor-infiltrating immune cells was examined by immunohistochemistry (IHC), flow cytometry, Enzyme-linked immunospot (ELISPOT), T cell depletions in vivo, Nanostring analysis and RNAscope.ResultsA significant reduction in tumor weight and number of metastases was found, as well as a significant improved survival of the NAM+GEM group compared with all control groups. IHC and flow cytometry showed a significant decrease in tumor-associated macrophages and myeloid-derived suppressor cells in the tumors of NAM+GEM-treated mice. This correlated with a significant increase in the number of CD4 and CD8 T cells of NAM+GEM-treated tumors, and CD4 and CD8 T cell responses to tumor-associated antigen survivin, most likely through epitope spreading. In vivo depletions of T cells demonstrated the involvement of CD4 T cells in the eradication of the tumor by NAM+GEM treatment. In addition, remodeling of the tumor stroma was observed with decreased collagen I and lower expression of hyaluronic acid binding protein, reorganization of the immune cells into lymph node like structures and CD31 positive vessels. Expression profiling for a panel of immuno-oncology genes revealed significant changes in genes involved in migration and activation of T cells, attraction of dendritic cells and epitope spreading.ConclusionThis study highlights the potential of NAM+GEM as immunotherapy for advanced pancreatic cancer.

A novel method to identify and monitor endogenous tumor-reactive T cells by high expression of CD11a (LFA-1) and PD-1 (CD279) as immunologic readout for evaluating the efficacy of PD-1 blockade.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 3037-3037
Author(s):  
Haidong Dong ◽  
Svetomir Markovic ◽  
Christopher J Krco ◽  
Eugene D. Kwon
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Stage Iv ◽  
High Expression ◽  
Mouse Tumor ◽  
Cytotoxic Lymphocytes ◽  
Phenotypic Analysis ◽  
Activated T Cells ◽  
Cell Immunity

3037 Background: Tumor immunotherapies directed towards enhancing natural or endogenous anti-tumor T-cell immunity in patients with advanced malignancies are currently being implemented in clinic with promising results. In order to optimize therapeutic protocols and monitor the effectiveness of such therapies, a reliable T-cell marker is needed. Methods: We utilized CD11a (LFA-1, lymphocyte functional-associated antigen 1), an integrin up-regulated on effector and memory CD8 T-cells, and PD-1 (programmed death-1), an immunoregulatory receptor expressed by activated T cells, as biomarkers to identify, quantitate and monitor endogenous tumor-reactive cytotoxic lymphocytes (CTLs) in two mouse tumor models and the peripheral blood (PB) of 12 patients with stage IV melanoma. Results: High expression of CD11a and PD-1 was identified among CD8 T-cells residing within primary and metastatic murine tumor sites, as well as in spontaneous murine breast cancer tissues. In the PB of melanoma patients, tumor antigen-specific CD8 T cells were associated with a population of CD11a high CD8 T-cells which co-expressed high levels of PD-1, as opposed to eleven healthy donors who had a much lower frequency of PD-1+ CD11a high CD8 T-cells (p <0.0001). Phenotypic analysis showed that CD11a high CD8 T-cells are proliferating (Ki67 positive) activated (CD62L low, CD69 high) T-cells. Increased CD11a high CD8 T-cells and delayed tumor growth were observed in PD-1 deficient mice, suggesting that the antitumor effector function of CD8 T cells is compromised by co-expression of elevated levels of PD-1. Conclusions: CD11a high CD8 T-cell population expresses high levels of PD-1 and is likely the cellular target of PD-1 blockade therapy. High expression of CD11a (LFA-1) and PD-1 (CD279) by CD8 T-cells may represent a novel biomarker to identify and monitor endogenous tumor-reactive CTLs. This may not only provide an immunological readout for evaluating the efficacy of therapy, but also contribute to the selection of patients with solid malignancies likely to benefit from anti-PD-1 therapy.

Nonclinical evaluation of the combination of mouse IL-21 and anti- mouse CTLA-4 or PD-1 blocking antibodies in mouse tumor models.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 3019-3019 ◽  
Author(s):  
Maria Jure-Kunkel ◽  
Mark Selby ◽  
Katherine Lewis ◽  
Gregg Masters ◽  
Jose Valle ◽  
...  
Keyword(s):  
T Cell ◽  
Antitumor Activity ◽  
Nk Cell ◽  
Phase Iii ◽  
Tumor Growth Inhibition ◽  
Clinical Activity ◽  
Mouse Tumor ◽  
Synergistic Activity ◽  
Tumor Models ◽  
Mouse Tumor Models

3019 Background: Interleukin 21 (IL-21), a γc chain family cytokine, is produced primarily by CD4+ T cells and has many effects on immune cells, including enhancing CD8+ T cell and NK cell proliferation and cytotoxicity. Recombinant IL-21 (rIL-21) therapy resulted in objective responses in ~20% of melanoma and renal cell carcinoma patients. In mouse models, monoclonal antibody (mAb) blockade of CTLA-4 prolongs antigen-specific T cell responses, while blockade of programmed death 1 (PD-1) reverses tumor induced T cell suppression. Ipilimumab, a CTLA-4 blocking mAb, significantly improved overall survival in patients with metastatic melanoma in 2 phase III trials, and in phase I studies a PD-1 blocking mAb (nivolumab) has antitumor activity in various cancers. Side effect profiles for each mAb have been related to their mechanism and are generally manageable. It was hypothesized that combination of IL-21 plus CTLA-4 or PD-1 blockade may enhance antitumor responses, potentially leading to improved clinical activity. Methods: Preclinical studies were conducted to test the antitumor activity of mouse IL-21 (mIL-21) in combination with an anti-mouse PD-1 (mPD-1) mAb (4H2-IgG1) or with an anti-mCTLA-4 blocking mAb (9D9-IgG2b) in syngeneic mouse tumor models, including MC38, CT-26, EMT-6, and B16F10. mIL-21 was tested at doses ranging from 50-200 μg/dose, administered up to 3d/wk. mCTLA-4 mAb or mPD-1 mAb were administered 3-4x total at 200-300 μg/dose. Results: Combination treatments produced enhanced antitumor activity vs. monotherapy. In the MC38 model, mIL-21 treatment led to 30% median tumor growth inhibition (TGI) by d29, while mPD-1 mAb produced 60% median TGI and 1/10 tumor-free mice. Combination of both agents led to synergistic antitumor activity, with complete regressions (CR) in 7/10 mice and 99.9% median TGI (p=0.046). CTLA-4 mAb + mIL-21 also produced synergistic activity in the MC38 model. By d21, mIL-21 monotherapy induced 34% TGI while CTLA-4 mAb resulted in 28% TGI, with no CR in either group. Combination resulted in 6/8 mice with CR and 86% TGI (p<0.05). Conclusions: These results support the use of rIL-21+nivolumab and rIL-21+ipilimumab in recently initiated clinical trials.

scholarly journals 778 Modulating tumor microenvironment with arginase-1 specific T cells

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A813-A813
Author(s):  
Evelina Martinenaite ◽  
Mia Aaboe Jørgensen ◽  
Rasmus Erik Johansson Mortensen ◽  
Shamaila Munir Ahmad ◽  
Stine Emilie Weis-Banke ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Microenvironment ◽  
Memory T Cells ◽  
Ethics Committee ◽  
Mouse Tumor ◽  
Immune Modulators ◽  
Arginase 1 ◽  
Mouse Tumor Models

BackgroundIO112 is an immune modulatory cancer therapy under preclinical development to target arginase-1-expressing tumor cells and immune inhibitory myeloid cells, such as myeloid derived suppressor cells (MDSCs), and tumor associated macrophages (TAMs). Arginase-1 acts as a metabolic immune regulator at the tumor site by reducing availability of L-arginine to the infiltrating immune cells thus reducing T cell functionality and proliferation. Previously, we demonstrated that IO112 triggers activation of spontaneous CD4+ and CD8+ T-cell responses against arginase-1, found in both cancer patients and healthy individuals.1 These T cells are present in the memory T cell compartment, and are activated in arginase-1 inducing conditions, such as presence of TH2 cytokines IL-4 or IL-13 in vitro.2 3 In this study we aimed to explore the role of arginase-1-specific T cells as immune modulators in immune homeostasis and tumor microenvironment for the development of IO112 immunomodulatory therapy.MethodsHuman arginase-1-specific T cells were isolated and expanded for functional characterization of reactivity against arginase-1 expressing target cells as well as subsequent phenotyping of the targeted arginase-1 positive cells. Syngeneic C57BL/6 mouse tumor models were used to assess the therapeutic efficacy of IO112.ResultsWe show that arginase-1-specific memory T cells specifically recognize arginase-1 expressing cells, such as mRNA transfected autologous dendritic cells (DCs) and B cells as well as M2 polarized macrophages in vitro. In addition, activated arginase-1-specific T cells produce pro-inflammatory cytokines IFNγ and TNFα. Secretion of TH1 cytokines by these T cells suggests that they may act as potent immune modulators in the tumor microenvironment, since many arginase-1 expressing myeloid cells are not terminally differentiated and they can be re-polarized to an immunostimulatory, M1-like phenotype. We also observed that targeting of M2-polarized arginase-1 expressing monocytic leukemia cell line THP-1 with arginase-1-specific CD4+ T cells induces upregulation of PD-L1 on the THP-1 cells. Furthermore, we demonstrate anti-tumor activity of IO112 in syngeneic mouse tumor models (B16 and MC38), both as monotherapy and in combination with anti-PD-1 treatment. The therapeutic effect was associated with increased immune infiltration in the IO112-treated mice compared to the control.ConclusionsWe demonstrate that arginase-1 specific T cells can influence the polarization of arginase-1-expressing immune cells. Our study provides evidence that IO112 immune therapy against arginase-1 is an attractive way of modulating the immune suppressive tumor microenvironment for therapeutic benefit. With this rationale, we are currently undertaking Investigational New Drug (IND) application enabling studies to explore this approach in a clinical setting.ReferencesMartinenaite E, Mortensen REJ, Hansen M, Holmström MO, Ahmad SM, Jørgensen NGD, Met Ö, Donia M, Svane IM, Andersen MH. Frequent adaptive immune responses against arginase-1. Oncoimmunology 2018;7(3):e1404215.Martinenaite E, Ahmad SM, Svane IM, Andersen MH. Peripheral memory T cells specific for Arginase-1. Cell Mol Immunol 2019;16(8):718–719.Martinenaite E, Ahmad SM, Bendtsen SK, Jørgensen MA, Weis-Banke SE, Svane IM, Andersen MH. Arginase-1-based vaccination against the tumor microenvironment: the identification of an optimal T-cell epitope. Cancer Immunol Immunother 2019;68(11):1901–1907.Ethics ApprovalThis study was approved by the Scientific Ethics Committee for The Capital Region of Denmark and Danish Ethics Committee on experimental animal welfare.

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.

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