569 Targeting IL-15 delivery to PD-L1 expressing tumors with an Anti-PD-L1-IL-15 cytokine fusion IgM to enhance T Cell and NK Cell Mediated tumor cytotoxicity

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A603-A603
Author(s):  
Angus Sinclair ◽  
Thierry Giffon ◽  
Dean Ng ◽  
Poonam Yakkundi ◽  
Hope Lancero ◽  
...  
Keyword(s):  
T Cells ◽  
Mouse Models ◽  
Heavy Chain ◽  
Cd8 T Cells ◽  
High Avidity ◽  
Human Pbmcs ◽  
High Affinity ◽  
J Chain ◽  
Complete Tumor

BackgroundTherapeutic antibodies inhibiting PD-1/PD-L1 have demonstrated clinical efficacy though only a fraction of patients respond. Combinations are being explored to enhance responses including anti-PD-1/PD-L1 IgG antibodies with IL-15-pathway stimulating agents to remove PD-1 immunosuppressive signaling and enhance anti-tumor NK and memory CD8 T cell expansion and survival. We have engineered an anti-PD-L1 pentameric high affinity, high avidity IgM, to target low PD-L1 expressing tumors, with an IL-15 superagonist fused to the joining (J) chain.MethodsAn anti-PD-L1 IgM was generated by grafting heavy chain variable regions of a high affinity IgG onto the IgM heavy chain framework and co-expressed with the light chains. The IL-15 superagonist fused to the J chain generated PDL1-ISA. Anti-PD-L1 binding was performed using recombinant antigen ELISAs and on cells by FACS. Reporter assays and PBMCs were used for potency testing. Cytokines were evaluated by CBA assays. In vitro cytotoxicity assays used luciferase tagged MDA-MB-231 cells with PBMCs, NK or CD8 T cells. Pharmacodynamic and efficacy studies were conducted in syngeneic and humanized mouse models.ResultsThe parental anti-PD-L1 IgM antibody bound recombinant and cellular PD-L1 more potently than an IgG antibody with the same binding domain. In functional PD-L1 and PD-1 blocking studies the anti-PD-L1 IgM was as efficacious as the IgG. PDL1-ISA provided a potent proliferation signal to primary human NK and CD8 T cells in vitro with little/no impact on regulatory or CD4 T cells. Limited cytokines were detected following 3–4 days culture with human PBMCs. PDL1-ISA had similar potencies for both human and cynomolgus CD8 T cells, and a 2–3-fold lower potency for mouse cells. Pharmacodynamic studies in humanized and BALB/c mice showed transient and dose-dependent increases in circulating NK and CD8 T cells. PDL1-ISA enhanced in vitro killing of PD-L1 positive MDA-MB-231-Luc cells by human PBMCs, CD8 T and NK cells compared to the anti-PD-L1 IgM (no IL-15). PDL1-ISA also demonstrated efficacy in a hPD-L1-CT26 HuCELL mouse model, with most treated animals having complete tumor regressions. Durable anti-tumor immune memory responses were observed upon tumor re-challenge.ConclusionsWe have engineered an IL-15 immunostimulatory anti-PD-L1 IgM antibody that binds PD-L1 more potently than an IgG, stimulates NK and CD8 expansion in vitro and in vivo and induces complete tumor regressions in mouse models. This approach may enhance tumor localization of immunostimulatory cytokine IL-15 though the high affinity and high avidity binding to PD-L1 to improve anti-tumor responses and minimize toxicity.

scholarly journals 711 IGM-7354 is an anti-PD-L1 IgM antibody and IL-15 cytokine fusion that enhances NK and CD8+ T cell proliferation and tumor cytotoxicity plus potently reverses T cell exhaustion

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A740-A740
Author(s):  
Thierry Giffon ◽  
Melanie Desbois ◽  
Dean Ng ◽  
Poonam Yakkundi ◽  
Marigold Manlusoc ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Cynomolgus Monkey ◽  
Cd8 T Cell ◽  
High Avidity ◽  
T Cell Exhaustion ◽  
Cell Exhaustion ◽  
High Affinity

BackgroundWhile approved PD-1/PD-L1 inhibitory antibodies have demonstrated clinical efficacy in certain cancer patients, relapse following a primary response is often observed. Enhancing anti-tumor immune responses with an immunostimulatory cytokine, IL-15 is an attractive combination strategy to enhance anti-tumor NK and memory CD8+ T cell expansion and survival. We have developed IGM-7354, a high affinity, high avidity anti-PD-L1 pentameric IgM antibody with an IL-15Rα chain and IL-15 fused to the joining (J) chain, designed to deliver IL-15 to PD-L1 expressing tumors for enhancing anti-tumor immune responses.MethodsIGM-7354 was generated by grafting heavy chain variable regions of a high affinity humanized anti-PD-L1 IgG onto the IgM heavy chain framework, co-expressed with the light chain and the J chain which included a single IL-15Rα and IL-15 fusion. Binding ELISAs were performed using recombinant antigens. Human and cynomolgus monkey PBMCs were used for potency testing. Reversal of T cell exhaustion was tested using in vitro MLR. In vitro cytotoxicity assays were performed with luciferase-tagged MDA-MB-231 cells and PBMCs. In vivo pharmacodynamic studies were conducted in mice and cynomolgus monkeys.ResultsIGM-7354 bound human and cynomolgus monkey PD-L1 with the same affinity but did not bind to rat or mouse PD-L1. In addition, the IL-15 component of IGM-7354 bound to human and cynomolgus β chain of the trimeric IL-15 receptor with similar affinities, but with weaker binding affinity to rodent IL-15Rβ. Using in vitro assays with PBMCs, IGM-7354 dose dependently enhanced the proliferation of human and cynomolgus monkey NK and CD8+ T cells. Furthermore, IGM-7354 was able to reverse T cell exhaustion in an in vitro MLR beyond that of an IL-15/IL15Rα complex or anti-PD-L1 IgM or IgG alone, as demonstrated by an increase in activation and effector cytokine secretion. IGM-7354 also enhanced in vitro killing of PD-L1-expressing MDA-MB-231 breast cancer cells by human PBMCs. Pharmacodynamic studies in an MDA-MB-231 xenograft mouse model showed dose-dependent increases in circulating NK and CD8+ T cells and tumor infiltrating lymphocytes, which correlated with tumor regression. In cynomolgus monkeys, intravenous administration of IGM-7354 was well tolerated and dose dependently induced the proliferation of NK and CD8+ T cells.ConclusionsIGM-7354 stimulates NK and CD8+ T cell expansion in vitro and in vivo plus induces tumor regressions in mouse tumor models. This approach may enhance tumor localization of the immunostimulatory cytokine IL-15 through high affinity and high avidity binding to PD-L1 thereby improving anti-tumor responses and minimizing toxicity.Ethics ApprovalAll animal studies were conducted according to approved Institutional Animal Care and Use Committee (IACUC) protocols of the testing facilities.

Use of Gene-Modified T-Cells as Antigen Presenting Cells (T-APC) for Vaccination Against Myeloma Antigens.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2758-2758
Author(s):  
Larry D. Anderson ◽  
Danielle R. Cook ◽  
Carolina Berger ◽  
David G. Maloney ◽  
Stanley R. Riddell
Keyword(s):  
T Cells ◽  
T Cell ◽  
Transgenic Mouse ◽  
Cd8 T Cells ◽  
Genetically Modified ◽  
Patient Specific ◽  
High Avidity ◽  
Vaccine Strategy ◽  
Myeloma Cells

Abstract Multiple myeloma is incurable with currently available standard treatments, and novel therapies with lower toxicity, including immunological therapies, are needed. Myeloma cells express class I MHC molecules and several potentially immunogenic proteins. Candidate target antigens, other than the patient-specific immunoglobulin idiotype, include cancer-testis antigens, such as MAGE-C1 (CT-7), and tissue differentiation antigens, such as B-Cell Maturation Antigen (BCMA). We have isolated, from normal donors, CD8+ T-cells that are CT-7 and BCMA peptide-specific, suggesting that immunologic tolerance to these proteins is incomplete. A subset of these CD8+ T-cells with the highest avidity are capable of recognizing myeloma cells. However, the frequency of T-cells recognizing these peptides is very low. Vaccination offers a potential approach for augmenting the frequency of tumor-reactive T-cells, provided that a vaccine strategy can be developed that elicits high-avidity T-cells. We have previously shown that adoptive transfer of autologous gene-modified T-cells leads to the rapid development of potent CD8+ T-cell immunity against transgene products expressed in the transferred T-cells. The aims of this study were to determine if vaccination with T-cells modified to express the CT-7 or BCMA genes (T-APC) could induce anti-myeloma immunity in an HLA-A2 transgenic mouse model, and to map additional immunogenic epitopes of these proteins presented by HLA-A2. To address this we genetically modified HLA-A2 transgenic mouse T-cells with retroviral vectors encoding the candidate myeloma antigens CT-7 and BCMA, or with a control vector encoding green fluorescent protein (GFP). The gene-modified T-APC were injected intravenously into HLA-A2 transgenic mice, and ELISPOT and cytotoxicity assays were performed on splenocytes from immunized mice to evaluate T-cell recognition of target cells expressing CT-7 or BCMA (including human myeloma cell lines). T-cell responses specific for CT-7, BCMA, and control antigens were elicited following gene-modified T-APC immunization, and in some cases these T-cells were capable of recognizing human myeloma cells. Furthermore, responses to CT-7 have been mapped to two different dominant CT-7 peptides. CD8+ T-cells from some normal A2+ donors also recognized these two epitopes after in vitro peptide stimulation, suggesting that these epitopes may be applicable to human myeloma therapy. Characterization of the BCMA target peptide(s) is ongoing. The ease with which T-cells can be obtained, genetically-modified, and expanded in vitro, together with data showing potent immunogenicity, suggests that T-APC vaccination should be evaluated as an alternative cell based vaccine strategy for human cancer therapy.

Gene Therapy With a High-Affinity Single-Chain p53-Specific TCR Mediates Potent Anti-Tumor Response Without Inducing Gvhd In Vivo

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1657-1657
Author(s):  
Hakim Echchannaoui ◽  
Jutta Petschenka ◽  
Edite Antunes ◽  
Matthias Theobald
Keyword(s):  
T Cells ◽  
Gene Transfer ◽  
Mouse Models ◽  
Adoptive Transfer ◽  
High Avidity ◽  
Single Chain ◽  
High Affinity ◽  
Tumor Associated Antigen ◽  
Human T Cells

Abstract The adoptive transfer of tumor-reactive cells is a promising approach in the treatment of human malignancies, but the challenge of isolating T cells with high-avidity for tumor antigens in each patient has limited its widespread application. Using HLA-A2.1 transgenic mice, we have demonstrated the feasibility of T-cell receptor (TCR) gene transfer into T cells to circumvent self-tolerance to the widely expressed human p53(264-272) tumor-associated antigen and developed approaches to generate high-affinity CD8-independent TCR. However, a safety concern of TCR gene transfer is the risk of pairing between introduced and the naturally expressed endogenous TCR chains, resulting in the generation of self-reactive T cells (off-target autoimmunity). We first genetically modified p53TCR constructs to minimize mispairing and improve correct pairing of the introduced TCR. We and others have shown that, cysteine modifications are able to increase the expression of the introduced TCR but fail to prevent mispairing formation in mouse and human T cells. To further enhance preferential TCR pairing, cell surface expression and TCR function, we introduced additional cysteine residues into the TCR α and β chain constant domains along with codon-optimization of the TCR sequences and cloning of the TCR constructs into one single 2A-based retroviral vector. To overcome TCR mispairing formation, we designed a single chain (sc) TCR by connecting the variable TCRa domain to the TCRb chain via a short peptide linker co-expressed with a truncated constant TCR a domain. Beside off-target toxicity, adoptive transfer of high-avidity T cells may potentially cause severe on-target toxicity for normal cells expressing low level of antigens. In this respect, pre-clinical in vivo studies are still missing. Here, we evaluated the safety issues raised by the risk of p53TCR gene transfer-associated on/off-target toxicities in relevant mouse models of adoptive transfer. In vitro studies showed that, scTCR-modified CD4+ and CD8+ T cells displayed similar high-avidity compared to the full-length TCR, as determined by peptide titration in cytotoxicity assays and were able to mediate specific lysis of p53 mutant A2.1+ tumor cells. Though, genetic modifications preserved the antigen specificity of these TCRs, the full-length version of the TCR could not prevent mispairing-mediated lethal off-target autoimmunity in vivo. In sharp contrast, T cells engrafted with the modified scTCR did not induce graft-versus-host disease (GVHD) following adoptive transfer. We next assessed the potential of scTCR-modified T cells to cause on-target autoimmunity in vivo, using mice which express the human wild type p53 and A2.1Kb (Hupki-A2.1Kb). We found that lymphodepleting preconditioning regimens plus vaccination-induced expansion of transferred TCR-specific T cells did not result in a depletion of hematopoietic cells, as mice recovered normal white blood cell counts, including lymphocytes and monocytes and survived without any sign of toxicity. Importantly, our study demonstrated that high-avidity scTCR-engineered human T cells were able to eradicate established tumors and persist for more than 6 months after infusion without inducing xeno-GVHD in NodScid IL-2R gamma chain-null mice. Taken together, our study provided evidence that an optimized high-affinity scTCR-specific for the broadly expressed tumor-associated antigen p53(264-272) can eradicate p53+A2.1+ tumor cells in vivo without inducing off-target or self-directed toxicities in humanized mouse models of adoptive T-cell transfer. These data strongly support the improved safety and therapeutic efficacy of high-affinity scp53TCR for TCR-based immunotherapy of p53-associated malignancies. Disclosures: No relevant conflicts of interest to declare.

High Avidity Leukemia-Associated Antigen-Specific CD8+ T Cells Preferentially Localize to the Bone Marrow in Patients with Myeloid Malignancies.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2763-2763
Author(s):  
J. Jopseph Melenhorst ◽  
Phillip Scheinberg ◽  
Pratip K. Chattopadhyay ◽  
Emma Gostick ◽  
Mario Roederer ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
Heavy Chain ◽  
Cd8 T Cells ◽  
Cd8 T Cell ◽  
Effector Memory ◽  
Cell Populations ◽  
High Avidity ◽  
Myeloid Malignancies

Abstract Both acute and chronic myeloid leukemias (AML and CML) and myelodysplastic syndromes (MDS) over-express and present self-antigens such as the HLA-A*0201-restricted proteinase 3 (PR1) and Wilm’s tumor-1 (WT1) epitopes, making these leukemia-associated antigens selectively amenable to immunotherapeutic intervention. Here, we examined the antigen avidity properties of circulating and bone marrow-resident CD8+ T cells specific for PR1 and WT1 in patients with AML (n=11), CML (n=10) and MDS (n=3). A total of 19 bone marrow (BM) samples and 27 peripheral blood (PB) samples were studied both prior to and following stem cell transplantation (SCT). Cognate HLA-A*0201 tetramers with identical TCR docking platforms were produced using three distinct monomeric HLA-A*0201 complexes with differential coreceptor binding properties to dissect the avidity of antigen binding directly ex vivo: “CD8-null” tetramers, which contain a compound D227K/T228A mutation in the a3 domain of the heavy chain that abrogates CD8 binding; wildtype tetramers; and, “CD8-enhanced” tetramers, which contain a Q115E mutation in the a2 domain of the heavy chain that moderately increases CD8 binding. We have shown previously that CD8-null tetramers engage only high avidity antigen-specific CD8+ T cells; in contrast, CD8-enhanced tetramers can engage populations of antigen-specific CD8+ T cells with low avidities that fall below the threshold for detection with wildtype tetramers. Using these reagents, we developed a polychromatic flow cytometric panel that enabled the simultaneous assessment of phenotype, function and avidity within antigen-specific CD8+ T cell populations. Either PR1- and/or WT1-specific CD8+ T cells were identified in 12/19 BM samples and 6/27 PB samples. Notably, one of the pre-SCT samples contained only low avidity leukemia-associated antigen-specific CD8+ T cells; in contrast, all of the specific populations identified in the post-SCT samples engaged their cognate antigen with high avidity. In 5/7 patients, analysis of paired BM/PB samples revealed the presence of high avidity PR1- and/or WT1-specific CD8+ T cells confined almost exclusively to the BM. Phenotypic analysis demonstrated a mixture of central and effector memory cells in all cases, thereby confirming that these PR1- and WT1-specific CD8+ T cell populations were antigen-experienced. Thus, high avidity CD8+ T cells specific for leukemia-associated antigens are present in vivo and preferentially localize to BM in myeloid malignancies.

scholarly journals Bromodomain and Extraterminal (BET) Domain Inhibition with PLX51107 and PLX2853 Improves Survival and Decreases Acute GVHD Severity in Murine Models

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4429-4429
Author(s):  
Hannah K. Choe ◽  
Yandi Gao ◽  
Katiri Snyder ◽  
Ben Powell ◽  
Gideon Bollag ◽  
...  
Keyword(s):  
T Cells ◽  
Biological Activity ◽  
T Cell ◽  
Mouse Model ◽  
Mouse Models ◽  
Cd8 T Cells ◽  
In Vitro Studies ◽  
Oral Gavage

Introduction: Acute Graft-versus-Host Disease (aGVHD) affects 30-70% of all allogeneic stem cell transplant (alloSCT) recipients, contributing to high non-relapse mortality. aGVHD is due to donor T cell cytotoxic inflammatory effects stimulated by exposure to foreign host antigens. Epigenetic modulation by BET inhibition boasts anti-inflammatory effects. BET proteins are a class of epigenetic "reader molecules," functioning as key mediators of transcription. BET proteins regulate inflammatory gene expression and are targetable. BET inhibition decreases NF-kB dependent cytokine expression and Th1/Th17 differentiation without affecting regulatory T cell differentiation. BET inhibition disrupts BRD4 interaction with the acetylated component of NF-kB, RelA. Therefore, we hypothesize that BET inhibition is a feasible and effective strategy to mitigate T cell mediated aGVHD inflammation. In this study, we have used PLX51107 and PLX2853 - novel BET inhibitors developed by Plexxikon Inc that possess a unique binding mode and high bioavailability ideal for preclinical evaluation. PLX2853 (second generation) was designed to increase potency and improve tolerability. Materials and Methods: aGVHD allogeneic mouse model: Lethally irradiated (1200 cGy) B6D2F1 recipients received T cell depleted bone marrow cells (TCD-BM, 10x106) and CD45.1+ B6 splenocytes (15x106) intravenously via tail vein injection. Recipients were treated by oral gavage, 3x weekly with PLX51107 (10 mg/kg), PLX2853 (4 mg/kg) or vehicle. We evaluated two dosing schedules - starting at day +1 or day +7 after transplant in the PLX51107 studies and day +1 only after infusion of allogeneic CD45.1+ B6 splenocytes in the PLX2853 studies. Survival and clinical aGVHD scores were assessed. Xenogeneic mouse model: NSG mice were conditioned with 50 cGy X-ray irradiation and injected with 15-20x106 human PBMCs and treated with PLX2853 (4 mg/kg) or vehicle starting day +1. Survival was assessed. Graft-versus-Tumor model: In vivo: Lethally irradiated F1 mice were intravenously injected with firefly luciferase-transduced murine mastocytoma P815 cells on day 0 with B6 TCD-BM ± allogeneic B6 splenocytes (n=8 per cohort). Recipients were treated with PLX2853 (4 mg/kg) or vehicle (oral gavage, 3x weekly) starting at day +1 post-transplant. Survival was assessed. In vitro: Murine CD45.1 B6 CD8+ T cells were stimulated in vitro with PMA/Ionomycin ± PLX2853 (10nM) for 5 days and then degranulation was analyzed in response to P815 tumor challenge to evaluate CTL capacity via flow cytometry of intracellular CD107a expression. Study designs are illustrated in the Figure (Panel A). Results: PLX51107 demonstrates potent biological activity and improves survival in a murine model of aGVHD. Administration of PLX51107 dramatically improved survival of recipient mice (B) and reduced aGVHD clinical scores (C). PLX2853 significantly improves survival in multiple mouse models of aGVHD. Our in-vitro data show that PLX2853 (IC50 ~10nM) is more potent than PLX51107 (IC50 ~500nM). Therefore, we validated the biological activity and efficacy of PLX2853 in mouse models of aGVHD. PLX2853 significantly prolonged survival of allogeneic transplanted recipient mice (D) and resulted in reduced clinical scores (E). Recipient mice in the xenogeneic mouse model showed improved survival with PLX2853 treatment (F). PLX2853 maintains Graft Versus Tumor response in vivo and does not abrogate CD8+ cytotoxic T lymphocyte (CTL) responses in vitro. BET inhibition retained beneficial GVT effects as seen by improvement in survival comparable to vehicle group (G). PLX2853 treated CD8+ T cells showed comparable degranulation to control as measured by CD107a mobilization (H, I). These results suggest that BET inhibition does not abrogate CD8+ CTL capacity, correlating to retention of GVT effects observed in vivo. Conclusions: PLX51107 was well tolerated at both day +1 and +7 initiation, demonstrating the future feasibility of BET inhibition as a prophylactic or therapeutic strategy for aGVHD. PLX2853 given at lower doses demonstrated similar improvements in survival and GVHD scoring, consistent with increased potency. Preliminary in vivo and in vitro studies of PLX2853 on GVT and on CD8+ CTLs show that PLX2853 retains GVT effects. Additional mechanistic in vivo and in vitro studies are ongoing. Figure Disclosures Powell: Plexxikon Inc.: Employment. Bollag:Plexxikon Inc.: Employment.

627 The DLL3-targeted half-life extended bispecific T cell engager (HLE BiTE®) immune-oncology therapy AMG 757 has potent antitumor activity in neuroendocrine cancer

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A663-A663
Author(s):  
Keegan Cooke ◽  
Juan Estrada ◽  
Jinghui Zhan ◽  
Jonathan Werner ◽  
Fei Lee ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Mouse Models ◽  
T Cell Activation ◽  
Phase 1 ◽  
Phase 1 Study ◽  
Human T Cells

BackgroundNeuroendocrine tumors (NET), including small cell lung cancer (SCLC), have poor prognosis and limited therapeutic options. AMG 757 is an HLE BiTE® immune therapy designed to redirect T cell cytotoxicity to NET cells by binding to Delta-like ligand 3 (DLL3) expressed on the tumor cell surface and CD3 on T cells.MethodsWe evaluated activity of AMG 757 in NET cells in vitro and in mouse models of neuroendocrine cancer in vivo. In vitro, co-cultures of NET cells and human T cells were treated with AMG 757 in a concentration range and T cell activation, cytokine production, and tumor cell killing were assessed. In vivo, AMG 757 antitumor efficacy was evaluated in xenograft NET and in orthotopic models designed to mimic primary and metastatic SCLC lesions. NSG mice bearing established NET were administered human T cells and then treated once weekly with AMG 757 or control HLE BiTE molecule; tumor growth inhibition was assessed. Pharmacodynamic effects of AMG 757 in tumors were also evaluated in SCLC models following a single administration of human T cells and AMG 757 or control HLE BiTE molecule.ResultsAMG 757 induced T cell activation, cytokine production, and potent T cell redirected killing of DLL3-expressing SCLC, neuroendocrine prostate cancer, and other DLL3-expressing NET cell lines in vitro. AMG 757-mediated redirected lysis was specific for DLL3-expressing cells. In patient-derived xenograft and orthotopic models of SCLC, single-dose AMG 757 effectively engaged human T cells administered systemically, leading to a significant increase in the number of human CD4+ and CD8+ T cells in primary and metastatic tumor lesions. Weekly administration of AMG 757 induced significant tumor growth inhibition of SCLC (figure 1) and other NET, including complete regression of established tumors and clearance of metastatic lesions. These findings warranted evaluation of AMG 757 (NCT03319940); the phase 1 study includes dose exploration (monotherapy and in combination with pembrolizumab) and dose expansion (monotherapy) in patients with SCLC (figure 2). A study of AMG 757 in patients with neuroendocrine prostate cancer is under development based on emerging data from the ongoing phase 1 study.Abstract 627 Figure 1AMG 757 Significantly reduced tumor growth in orthotopic SCLC mouse modelsAbstract 627 Figure 2AMG 757 Phase 1 study designConclusionsAMG 757 engages and activates T cells to kill DLL3-expressing SCLC and other NET cells in vitro and induces significant antitumor activity against established xenograft tumors in mouse models. These preclinical data support evaluation of AMG 757 in clinical studies of patients with NET.Ethics ApprovalAll in vivo work was conducted under IACUC-approved protocol #2009-00046.

scholarly journals Immunodominant Cytomegalovirus Epitopes Suppress Subdominant Epitopes in the Generation of High-Avidity CD8 T Cells

Pathogens ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 956
Author(s):  
Kirsten Freitag ◽  
Sara Hamdan ◽  
Matthias J. Reddehase ◽  
Rafaela Holtappels
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Immune Escape ◽  
Cd8 T Cell ◽  
Antigenic Drift ◽  
Murine Cytomegalovirus ◽  
High Avidity ◽  
Infected Cells ◽  
Cd8 T Cell Memory

CD8+ T-cell responses to pathogens are directed against infected cells that present pathogen-encoded peptides on MHC class-I molecules. Although natural responses are polyclonal, the spectrum of peptides that qualify for epitopes is remarkably small even for pathogens with high coding capacity. Among those few that are successful at all, a hierarchy exists in the magnitude of the response that they elicit in terms of numbers of CD8+ T cells generated. This led to a classification into immunodominant and non-immunodominant or subordinate epitopes, IDEs and non-IDEs, respectively. IDEs are favored in the design of vaccines and are chosen for CD8+ T-cell immunotherapy. Using murine cytomegalovirus as a model, we provide evidence to conclude that epitope hierarchy reflects competition on the level of antigen recognition. Notably, high-avidity cells specific for non-IDEs were found to expand only when IDEs were deleted. This may be a host’s back-up strategy to avoid viral immune escape through antigenic drift caused by IDE mutations. Importantly, our results are relevant for the design of vaccines based on cytomegaloviruses as vectors to generate high-avidity CD8+ T-cell memory specific for unrelated pathogens or tumors. We propose the deletion of vector-encoded IDEs to avoid the suppression of epitopes of the vaccine target.

scholarly journals 453 Novel combination immunotherapy for boosting and priming immune responses in pancreatic cancer: strong anti-tumour effects with interleukin-15 and CD40 agonist treatment

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A480-A480
Author(s):  
Jonas Van Audenaerde ◽  
Elly Marcq ◽  
Bianca von Scheidt ◽  
Ashleigh Davey ◽  
Amanda Oliver ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
T Cells ◽  
Dendritic Cells ◽  
Natural Killer ◽  
Mouse Models ◽  
Cd8 T Cells ◽  
Tumour Growth ◽  
Immune Memory ◽  
Combination Immunotherapy ◽  
Interleukin 15

BackgroundWith the poorest 5-year survival of all cancers, improving treatment for pancreatic cancer is one of the biggest challenges in cancer research. In this era of combination immunotherapies, we sought to explore the potential of combining both priming and activation of the immune system. To achieve this, we combined a CD40 agonist with interleukin-15 and tested its potential in pancreatic cancer.MethodsTwo different mouse models of pancreatic cancer were used to assess the potential of this combination regimen. Therefore, effects on tumour growth kinetics and survival were charted. Differential effects on immune signatures was investigated using RNA sequencing. Functional immune subset involvement was tested using different immune depletion experiments and multicolour flow cytometry in different relevant immune sites. Immune memory was checked using re-challenge experiments.ResultsWe demonstrated profound reduction in tumour growth and increased survival of mice with the majority of mice being cured when both agents were combined, including an unprecedented dose reduction of CD40 agonist without losing any efficacy (fig 1). RNA sequencing analysis showed involvement of natural killer cell and T cell mediated anti-tumour responses and the importance of antigen-presenting cell pathways. This combination resulted in enhanced infiltration of tumours by both cytotoxic T cells and natural killer cells, as well as a striking increase in the ratio of CD8+ T cells over T regulatory cells. We also observed a significant increase in numbers of dendritic cells in tumour draining lymph nodes, particularly CD103+ dendritic cells with cross-presentation potential. A critical role for CD8+ T cells and involvement of natural killer cells in the anti-tumour effect was highlighted. Importantly, strong immune memory was established, with an increase in memory CD8+ T cells only when both interleukin-15 and the CD40 agonist were combined.Abstract 453 Figure 1Tumour kinetics and survival in Panc02 (left) and KPC (right) pancreatic cancer mouse modelsConclusionsWe demonstrated profound synergistic anti-tumour effects upon combination of CD40 agonist and interleukin-15 treatment in mouse models of pancreatic cancer. This preclinical data supports initiation of a first-in-human clinical trial with this combination immunotherapy strategy in pancreatic cancer.

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