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 Mechanisms of mouse spleen dendritic cell function in the generation of influenza-specific, cytolytic T lymphocytes.

1992 ◽  
Vol 176 (2) ◽  
pp. 519-529 ◽  
Author(s):  
R Nonacs ◽  
C Humborg ◽  
J P Tam ◽  
R M Steinman
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Mhc Class I ◽  
Mhc Class Ii ◽  
Cd4 T Cells ◽  
Cell Function ◽  
Class Ii ◽  
T Cell Response ◽  
Class I

We have evaluated the capacity of dendritic cells to function as antigen-presenting cells (APCs) for influenza and have examined their mechanism of action. Virus-pulsed dendritic cells were 100 times more efficient than bulk spleen cells in stimulating cytotoxic T lymphocyte (CTL) formation. The induction of CTLs required neither exogenous lymphokines nor APCs in the responding T cell population. Infectious virus entered dendritic cells through intracellular acidic vacuoles and directed the synthesis of several viral proteins. If ultraviolet (UV)-inactivated or bromelain-treated viruses were used, viral protein synthesis could not be detected, and there was poor induction of CTLs. This indicated that dendritic cells were not capable of processing noninfectious virus onto major histocompatibility complex (MHC) class I molecules. However, UV-inactivated and bromelain-treated viruses were presented efficiently to class II-restricted CD4+ T cells. The CD4+ T cells crossreacted with different strains of influenza and markedly amplified CTL formation. Cell lines that lacked MHC class II, and consequently the capacity to stimulate CD4+ T cells, failed to induce CTLs unless helper lymphokines were added. Similarly, dendritic cells pulsed with the MHC class I-restricted nucleoprotein 147-155 peptide were poor stimulators in the absence of exogenous helper factors. We conclude that the function of dendritic cells as APCs for the generation of virus-specific CTLs in vitro depends measurably upon: (a) charging class I molecules with peptides derived from endogenously synthesized viral antigens, and (b) stimulating a strong CD4+ helper T cell response.

T-cell epitopes within the complementarity-determining and framework regions of the tumor-derived immunoglobulin heavy chain in multiple myeloma

Blood ◽  
2003 ◽  
Vol 101 (12) ◽  
pp. 4930-4936 ◽  
Author(s):  
Lotta Hansson ◽  
Hodjattallah Rabbani ◽  
Jan Fagerberg ◽  
Anders Österborg ◽  
Håkan Mellstedt
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Mhc Class I ◽  
Heavy Chain ◽  
T Cell Response ◽  
Class I ◽  
Type I ◽  
T Cell Epitopes ◽  
Hla Binding

Abstract The idiotypic structure of the monoclonal immunoglobulin (Ig) in multiple myeloma (MM) might be regarded as a tumor-specific antigen. The present study was designed to identify T-cell epitopes of the variable region of the Ig heavy chain (VH) in MM (n = 5) using bioinformatics and analyze the presence of naturally occurring T cells against idiotype-derived peptides. A large number of human-leukocyte-antigen (HLA)–binding (class I and II) peptides were identified. The frequency of predicted epitopes depended on the database used: 245 in bioinformatics and molecular analysis section (BIMAS) and 601 in SYFPEITHI. Most of the peptides displayed a binding half-life or score in the low or intermediate affinity range. The majority of the predicted peptides were complementarity-determining region (CDR)–rather than framework region (FR)–derived (52%-60% vs 40%-48%, respectively). Most of the predicted peptides were confined to the CDR2-FR3-CDR3 “geographic” region of the Ig-VH region (70%), and significantly fewer peptides were found within the flanking (FR1-CDR1-FR2 and FR4) regions (P < .01). There were 8– to 10–amino acid (aa) long peptides corresponding to the CDRs and fitting to the actual HLA-A/B haplotypes that spontaneously recognized, albeit with a low magnitude, type I T cells (interferon γ), indicating an ongoing major histocompatibility complex (MHC) class I–restricted T-cell response. Most of those peptides had a low binding half-life (BIMAS) and a low/intermediate score (SYFPEITHI). Furthermore, 15- to 20-aa long CDR1-3–derived peptides also spontaneously recognized type I T cells, indicating the presence of MHC class II–restricted T cells as well. This study demonstrates that a large number of HLA-binding idiotypic peptides can be identified in patients with MM. Such peptides may spontaneously induce a type I MHC class I– as well as class II–restricted memory T-cell response.

Human T Cells with Distinct Specificities Mediate Graft-Versus-Leukemia Reactivity and Xenogeneic Graft-Versus-Host Disease in a NOD/Scid Mouse Model for Human Acute Leukemia.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1330-1330
Author(s):  
Sanja Stevanovic ◽  
Bart Nijmeijer ◽  
Marianke LJ Van Schie ◽  
Roelof Willemze ◽  
Marieke Griffioen ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class I ◽  
Mhc Class Ii ◽  
Class Ii ◽  
Cd4 T Cell ◽  
Class I ◽  
T Cell Clones ◽  
Cell Clones ◽  
Human T Cells

Abstract Abstract 1330 Poster Board I-352 Immunodeficient mice inoculated with human leukemia can be used as a model to investigate Graft-versus-Leukemia (GvL) effects of donor lymphocyte infusions (DLIs). In addition to GvL reactivity, treatment with DLI induces xenogeneic Graft-versus-Host Disease (GvHD) in mice, characterized by pancytopenia and weight loss. In patients treated with DLI for relapsed or residual leukemia after allogeneic stem cell transplantation, immune responses against non-leukemic cells may also cause GvHD. It has been suggested that GvL reactivity and GvHD, which co-develop in vivo, can be separated and that distinct T cells exist with the specific capacity to mediate GvL reactivity or GvHD. Since adoptive T cell transfer models that allow analysis of separation of GvL and GvHD are rare, we aimed to establish whether GvL reactivity and xenogeneic GvHD could be separated using our model of human leukemia-engrafted NOD/scid mouse after treatment with human donor T cells. In this study, non-conditioned NOD/scid mice engrafted with primary human acute lymphoblastic leukemic cells were treated with CD3+ DLI. Established tumors were effectively eliminated by emerging human T cells, but also induced xenogeneic GvHD. Flowcytometric analysis demonstrated that the majority of emerging CD8+ and CD4+ T cells were activated (HLA-DR+) and expressed an effector memory phenotype (CD45RA-CD45RO+CCR7-). To investigate whether GvL reactivity and xenogeneic GvHD were mediated by the same T cells showing reactivity against both human leukemic and murine cells, or displaying distinct reactivity against human leukemic and murine cells, we clonally isolated and characterized the T cells during the GvL response and xenogeneic GvHD. T cell clones were analyzed for reactivity against primary human leukemic cells and primary NOD/scid hematopoietic (BM and spleen cells) and non-hematopoietic (skin fibroblasts) cells in IFN-g ELISA. Isolated CD8+ and CD4+ T cell clones were shown to recognize either human leukemic or murine cells, indicating that GvL response and xenogeneic GvHD were mediated by different human T cells. Flowcytometric analysis demonstrated that all BM and spleen cells expressed MHC class I, whereas only 1-3 % of the cells were MHC class II +. Primary skin fibroblasts displayed low MHC class I and completely lacked MHC class II expression. Xeno-reactive CD8+ T cell clones were shown to recognize all MHC class I + target cells and xeno-reactive CD4+ T cells clones displayed reactivity only against MHC class II + target cells. To determine the MHC restriction of xeno-reactive T cell clones, NOD/scid bone marrow (BM) derived dendritic cells (DC) expressing high levels of murine MHC class I and class II were tested for T cell recognition in the presence or absence of murine MHC class I and class II monoclonal antibodies in IFN-g ELISA. Xeno-reactive CD8+ T cell clones were shown to be MHC class I (H-2Kd or H-2Db) restricted, whereas xeno-reactive CD4+ T cell clones were MHC class II (I-Ag7) restricted, indicating that xeno-reactivity reflects genuine human T cell response directed against allo-antigens present on murine cells. Despite production of high levels of IFN-gamma, xeno-reactive CD8+ and CD4+ T cell clones failed to exert cytolytic activity against murine DC, as determined in a 51Cr-release cytotoxicity assay. Absence of cytolysis by CD8+ T cell clones, which are generally considered as potent effector cells, may be explained by low avidity interaction between human T cells and murine DC, since flowcytometric analysis revealed sub-optimal activation of T cells as measured by CD137 expression and T cell receptor downregulation upon co-culture with murine DC, and therefore these results indicate that xenogeneic GvHD in this model is likely to be mediated by cytokines. In conclusion, in leukemia-engrafted NOD/scid mice treated with CD3+ DLI, we show that GvL reactivity and xenogeneic GvHD are mediated by separate human T cells with distinct specificities. All xeno-reactive T cell clones showed genuine recognition of MHC class I or class II associated allo-antigens on murine cells similar as GvHD-inducing human T cells. These data suggest that our NOD/scid mouse model of human acute leukemia may be valuable for studying the effectiveness and specificity of selectively enriched or depleted T cells for adoptive immunotherapy. Disclosures: No relevant conflicts of interest to declare.

Double Loading of Dendritic Cell MHC Class I and MHC Class II with an AML Antigen Repertoire Enhances Primary and Secondary T-Cell Responses In Vitro.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2529-2529
Author(s):  
William K. Decker ◽  
Dongxia Xing ◽  
Sufang Li ◽  
Simon N. Robinson ◽  
Hong Yang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class Ii ◽  
Cd8 T Cells ◽  
Class Ii ◽  
T Cell Response ◽  
Class I ◽  
Cross Presentation ◽  
Ifn Γ

Abstract Despite improvements in therapy for acute myelogenous leukemia (AML), a significant percentage of patients still relapse and succumb to their disease. Dendritic cell immunotherapy offers the promise of potentially effective supportive therapy for a variety of neoplastic conditions; and the use of DCs loaded with tumor antigens is now recognized as an important investigational therapy. Though a variety of methods have been used to load DC vaccines, the loading of the MHC class II compartment with tumor lysate has predominated. The priming of a class II-mediated (CD4) T-cell response may be crucial to the success of DC immunotherapy as such a response is likely required for the development of memory CD8+ T-cells. DC cross-presentation is credited with the ability of lysate-loaded DCs to prime both CD4 and CD8 T-cell responses, enabling the generation of CD8+ CTLs without the loading of the MHC class I compartment (i.e. the cytoplasm). Recently, however, several reports have raised doubts as to the efficiency of cross-presentation as a mechanism for CTL priming in vivo. To examine this issue, we have loaded human DCs with both AML tumor lysate and mRNA. This technique allows the full repertoire of class I antigens to be presented without dependence upon cross-presentation; and, moreover, provides a full complement of class II antigens necessary for CD4 T-cell priming and the generation of memory responses. Methods: CD14+ precursors were isolated from normal donor PBPCs by magnetic separation. Immature DCs were then generated by culturing precursors for six days in GM-CSF and IL-4. Lysate was produced by three successive freeze/thaw cycles of blasts. mRNA was extracted from blasts using Trizol and oligo-dT separation. Immature DCs were pulsed for three hours with AML lysate and subsequently electroporated with AML mRNA. Loaded DCs were matured for 48 hours with IL-1β, TNF-α, IL-6, and PGE2 and then used to prime autologous T-cells. Short-term responses were assayed on day 5 of the 1st stimulation. Memory responses were assayed on day 10 of a tertiary stimulation. Results: Doubly-loaded DCs can prime a superior T-cell response in vitro in comparison to that of singly-loaded DCs, demonstrating a 30–70% increase in IFN-γ ELISpots over lysate-loaded DCs (p<0.001) and a 3–4 fold increase in ELISpots in comparison to mRNA loaded DCs (p<0.001). These results were verified by flow cytometry which showed 35% of CD8+ T-cells primed by doubly-loaded DCs were CD69+/IFN-γ+ vs. 14% of CD8+ T-cells primed by lysate-loaded DCs (p<0.001). This enhancement may be based upon both an upregulation of CD83 surface expression (p<0.0019) of doubly-loaded DCs and/or the upregulation of B7.1/B7.2 that accompanies elevated CD40L signaling. Memory responses were also greatly improved, with a 126% increase in total ELISpots (double loaded DCs versus lysate loaded DCs; p<0.03) and a 187% increase in total IFN-γ secretion (p<0.03). Unloaded (p<0.01) and mRNA (p<0.007) loaded DCs exhibited a virtual inability to generate memory T-cells in vitro, suggesting that the perpetuation of the memory response is reliant upon T-cell help. Conclusion: DCs doubly-loaded with lysate and mRNA are more efficient in the generation of primary and secondary immune responses than are singly-loaded DCs. The clinical administration of such doubly-loaded DCs may offer an important therapeutic option to patients with AML.

scholarly journals The natural immune response to inhaled soluble protein antigens involves major histocompatibility complex (MHC) class I-restricted CD8+ T cell-mediated but MHC class II-restricted CD4+ T cell-dependent immune deviation resulting in selective suppression of immunoglobulin E production.

1993 ◽  
Vol 178 (3) ◽  
pp. 889-899 ◽  
Author(s):  
C McMenamin ◽  
P G Holt
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class I ◽  
Mhc Class Ii ◽  
Cd8 T Cells ◽  
Immunoglobulin E ◽  
Cd8 T Cell ◽  
T Cell Response ◽  
Class I

The immunological basis for atopy is currently ascribed to an inherent bias in the CD4+ T cell response to nonreplicating antigens presented at mucosal surfaces, resulting in dominance of the T helper 2 (Th2) interleukin 4 (IL-4)-producing phenotype, which favors IgE production. In contrast, the "normal" response to such antigens involves a predominance of interferon gamma (IFN-gamma)-producing Th1 clones. This difference has been suggested to be the result of active selection in atopics for Th2 (and hence against Th1) clones at the time of initial antigen presentation. In the study below, we demonstrate that the natural immune response to inhaled protein antigens, particularly in animals expressing the low immunoglobulin E (IgE) responder phenotype, includes a major histocompatibility complex (MHC) class I-restricted CD8+ T cell component, the appearance of which is associated with active suppression of IgE antibody production. Thus, continued exposure of rats to aerosolized ovalbumin (OVA) antigen elicits a transient IgE response, that is terminated by the onset of a state of apparent "tolerance" to further challenge, and this tolerant state is transferable to naive animals with CD8+ T cells. Kinetic studies on in vitro T cell reactivity in these aerosol-exposed rats demonstrated biphasic CD4+ Th2 responses which terminated, together with IgE antibody production, and coincident with the appearance of MHC class I-restricted OVA-specific IFN-gamma-producing CD8+ T cells. However, the latter were not autonomous in vitro and required a source of exogenous IL-2 for initial activation, which in CD(8+)-enriched splenocyte cultures could be provided by small numbers of contaminating OVA-specific CD4+ T cells. This represents the first formal evidence for the induction of an MHC class I-restricted T cell response to natural mucosal exposure to an inert protein antigen, and is consistent with a growing literature demonstrating sensitization of MHC class I-restricted CD8+ T cells by deliberate immunization with soluble proteins. We suggest that crossregulation of MHC class II-restricted CD4+ T cells via cytokine signals generated in parallel CD8+ T cell responses represents a covert and potentially important selection pressure that can shape the nature of host responses to nonreplicating antigens presented at mucosal surfaces.

Identification of Novel MHC Class I and Class II Epitopes of WT1 Using a Peptide Library Screen.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 2764-2764 ◽  
Author(s):  
Katayoun Rezvani ◽  
Stephan Mielke ◽  
Yasemin Kilical ◽  
Matthias Grube ◽  
Hiroshi Fujiwara ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Class Ii ◽  
Peptide Library ◽  
Class I ◽  
Cell Responses

Abstract Although several HLA-A*0201-restricted immunodominant peptides from the leukemia-restricted protein WT-1 are characterized, T cell responses to peptide sequences binding to other common class I and II epitopes of WT-1 remain almost completely unexplored. A more comprehensive definition of the WT-1 antigen would extend peptide antigen vaccines to individuals lacking HLA-A*0201 and *2402 and improve vaccine potency by recruiting both CD4+ and CD8+ T cell responses. Here we used a WT1 peptide library to identify WT-1 peptide sequences inducing CD4+ and CD8+ T cell responses in normal individuals and patients with AML and other myeloid leukemias. Six cases were studied. The library consisted of 110 15mer peptides overlapping by 11aa covering the entire WT-1 protein in 21 pools. Monocytes were isolated by plastic adherence and pulsed with peptide pools for 3 hours. Autologous CD8+ and CD4+ T cells were then added. Pools of peptides were prepared in such a way that each peptide was represented in two different peptide pools, allowing the identification of the respective peptide by responses in the two corresponding pools. Cells were harvested for RNA extraction and reverse transcription. Real time PCR (RQ-PCR) was used to identify peptide-specific induction of IFN-γ and IL-2 in CD8+ and CD4+ T cells. The SYFPEITHI binding motif software was then used to predict the probable HLA restriction for the candidate epitopes. To confirm candidate peptide immunogenecity and HLA restriction, selected peptides were synthesized and tested individually. In addition to the known HLA-A*0201 peptides WT37, WT126, WT187 and WT235 we identified 20 new MHC class I and II epitopes of WT1. Four were restricted by more than one HLA allele, demonstrating the promiscuity of epitope binding. One epitope (VPGVAPTLV) was restricted to HLA-A*0201 and HLA-B*5101. One epitope (SGQFTGTAGACRYGP) was restricted by a class I HLA allele, namely HLA-*6801 and a class II HLA allele, DR*1501. Two epitopes (YGPFGPPPPSQASGQ and QKKFARSDELVRHHN) were restricted by multiple MHC class II alleles. The proliferative response of CD4+ and CD8+ T cells to candidate peptides was confirmed using CFSE labeling. We now plan to characterize the antileukemic effects of CD4+ and CD8+ T cells induced by these peptides with a view to designing broad-spectrum vaccines inducing leukemia-reactive T cells across a wide range of HLA types.

scholarly journals Mechanistic diversity in MHC class I antigen recognition

2021 ◽  
Vol 478 (24) ◽  
pp. 4187-4202
Author(s):  
Camila R. R. Barbosa ◽  
Justin Barton ◽  
Adrian J. Shepherd ◽  
Michele Mishto
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
T Cell Response ◽  
Class I ◽  
Antigenic Peptides ◽  
Human Immune System ◽  
Mhc Class I Antigen ◽  
Human Immune

Throughout its evolution, the human immune system has developed a plethora of strategies to diversify the antigenic peptide sequences that can be targeted by the CD8+ T cell response against pathogens and aberrations of self. Here we provide a general overview of the mechanisms that lead to the diversity of antigens presented by MHC class I complexes and their recognition by CD8+ T cells, together with a more detailed analysis of recent progress in two important areas that are highly controversial: the prevalence and immunological relevance of unconventional antigen peptides; and cross-recognition of antigenic peptides by the T cell receptors of CD8+ T cells.

scholarly journals P04.03 Immune modulatory vaccine directed against IDO1-expressing immune cells elicits T cell-mediated anti-tumor immunity and enhances anti-PD1 responses

2020 ◽  
Vol 8 (Suppl 2) ◽  
pp. A37.2-A38
Author(s):  
S Dey ◽  
E Sutanto-Ward ◽  
KL Kopp ◽  
JB DuHadaway ◽  
A Mondal ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class I ◽  
Tumor Response ◽  
Ex Vivo ◽  
Class Ii ◽  
Class I ◽  
Peptide Vaccines ◽  
Ido1 Expression ◽  
Part Time

BackgroundIndoleamine 2,3-dioxygenase 1 (IDO1) is a tryptophan-catabolizing enzyme that contributes to immunoregulation at many levels, including suppressing effector T cells and inducing/activating regulatory T cells. Thus far, several therapeutic approaches to target IDO1 enzymatic activity have shown promise in preclinical models, however, results from the first major clinical trial were disappointing. The present study seeks to provide preclinical PoC data for the conceptually unique idea of developing an IDO1-targeted vaccine based on our earlier findings that humans exhibit intrinsic T cell reactivity against IDO1 epitopes1 suggesting the existence of a T cell-mediated, counter-regulatory mechanism directed against cells that express IDO1.Materials and MethodsIDO1-derived peptide vaccines were identified by measurement of vaccine-induced ex vivo response (IFNγ ELISpot) and demonstration of anti-tumor responses in CT26 tumor-bearing mice. To understand the vaccine’s mode of action, resected tumors were analyzed by immunofluorescence microscopy and flow cytometry.ResultsThe CT26 colon carcinoma model was selected for these studies based on evidence of high levels of IDO1 expression and responsiveness to IDO1 inhibition reported for these tumors. In silico-predicted H2d MHC class I and II-restricted IDO1 peptide sequences were tested and vaccine candidates were chosen after confirming ex vivo response and anti-tumor response in CT26. Therapeutic treatment of established CT26 tumors with MHC class I- and II-directed, IDO1-derived peptide vaccines elicited anti-tumor responses when administered alone, and the effect was further pronounced when combined, suggesting distinct mechanisms of action. In addition, a combination of IDO1 vaccine with anti-PD-1 antibody produced a combinatorial anti-tumor response beyond what was achieved with either agent alone. Consistent with this observation, adoptive transfer of isolated CD8+ T cells from class I and CD4+ T cells from class II peptide-vaccinated responder mice delayed tumor growth in treatment naïve mice. The class II-directed response was completely IDO1-dependent while the class I-directed response included an IDO1-independent component indicative of antigen spread. Examination into the tumors in vaccinated mice indicated that IDO1 vaccine treatment exerts its effect by selective reduction of IDO1 expression in the tumor microenvironment and concomitant expansion of activated CD4+ and CD8+ T cells.ConclusionsAs noted in humans, our data demonstrate that IDO1 is immunogenic in mice confirming that this endogenous protein is excluded from normal tolerance mechanisms. The observed immunotherapeutic efficacy of IDO1 peptide vaccines on their own and in combination with anti-PD-1 antibody support the rationale for ongoing clinical development of IDO1 peptide vaccine-based therapy. Future studies include further differentiation of the vaccine platform against other IDO1-targeting approaches, as well as decoding the underlying mechanism of cooperativity between anti-PD-1 antibody and IDO1 peptide vaccines.ReferenceSørensen RB, Hadrup SR, Svane IM, Hjortsø MC, Thor Straten P, Andersen MH. Indoleamine 2,3-dioxygenase specific, cytotoxic T cells as immune regulators. Blood 2011; 117(7): 2200–10Disclosure InformationS. Dey: None. E. Sutanto-Ward: None. K.L. Kopp: A. Employment (full or part-time); Significant; IO Biotech. J.B. DuHadaway: None. A. Mondal: None. I. Lecoq: A. Employment (full or part-time); Significant; IO Biotech. M. Zocca: A. Employment (full or part-time); Significant; IO Biotech. M.H. Andersen: A. Employment (full or part-time); Significant; IO Biotech. A.W. Pedersen: A. Employment (full or part-time); Significant; IO Biotech. A.J. Muller: F. Consultant/Advisory Board; Modest; IO Biotech.

458 Antitumor mechanisms of local radiation and combination immunotherapy in an immunologically cold model of neuroblastoma

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A486-A486
Author(s):  
Taylor Aiken ◽  
Julie Voeller ◽  
Amy Erbe ◽  
Alexander Rakhmilevich ◽  
Paul Sondel
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Mhc Class I ◽  
T Regulatory Cells ◽  
Immune Cell ◽  
Cell Depletion ◽  
Class I ◽  
Combination Immunotherapy ◽  
T Cell Depletion

BackgroundThe standard treatment for high-risk neuroblastoma includes a combination immunotherapeutic approach consisting of IL-2, GM-CSF, and monoclonal antibodies directed against GD2, a disialoganglioside preferentially expressed in neuroblastoma and melanoma (1). We recently described an effective a preclinical in-situ vaccination strategy combining local radiation therapy (RT), IL-2-linked to anti-GD2 monoclonal antibody (intratumoral immunocytokine, IT-IC), checkpoint inhibition (anti-CTLA4), and drivers of innate immunity (anti-CD40 and CpG) (2). This strategy is effective in curing mice with immunologically-cold neuroblastoma. We sought to better characterize the anti-tumor mechanisms that mediate this effect.MethodsMice bearing GD2-expressing, immunologically-cold neuroblastoma tumors (9464D-GD2) were treated with 12Gy RT and combination immunotherapy (IT-IC, anti-CTLA-4, CpG, anti-CD40) over 12 days as previously described (2). Depletion of individual immune cell sets during treatment was achieved by depleting monoclonal antibodies and confirmed by flow cytometry. T-cell receptor deficient (TCR KO) mice were used to confirm findings in T-cell depletion experiments. 9464D-GD2 parental cells have low MHC-I expression; subclones with low and moderate MHC Class I expression were obtained by flow cytometry sorting and the impact of MHC class I expression on immune cell infiltrate and survival was assessed.ResultsThe effectiveness of RT and combination immunotherapy was not significantly reduced by NK or T cell depletion, and TCR KO mice had similar tumor growth and survival to mice that underwent T-cell depletion. Moderate MHC class I expression did not slow tumor growth or improve survival in mice bearing 9464D-GD2 tumors (over those with low MHC-I) following treatment. Moderate MHC class I expression also did not alter individual immune cell subsets in treated tumors. Overall, increased infiltration of CD8 T-cells, CD4 T-cells, and depletion of T regulatory cells was observed in all treated tumors (p<0.05).Abstract 458 Figure 1Effect of MHC class I expression on response to RT and combination immunotherapy (IT-IC, anti-CTLA4, anti-CD40, CpG). A) Increased MHC class I expression in 9464D-GD2 derived tumors did not alter tumor growth or survival following treatment. B) Increased MHC class I expression did not alter immune subsets following treatment of 9464D-GD tumors with radiation and combination immunotherapy. Increased numbers of CD8+ and CD4+ T-cells was observed with both moderate and absent MHC class I expression. T regulatory cells were also effectively depleted in both treated groupsConclusionsTreatment with RT and combination immunotherapy (IT-IC, anti-CTLA4, anti-CD40, CpG) may act through mechanisms that are MHC class I, NK-cell and T-cell independent. Further investigation of the role of innate immunity and myeloid subsets in this scenario is warranted.AcknowledgementsResearch reported in this publication was supported by the National Cancer Institute of the National Institutes of Health under Award Number T32 CA090217.ReferencesYu AL, Gilman AL, Ozkaynak MF, London WB, Kreissman SG, Chen HX, et al. Anti-GD2 Antibody with GM-CSF, Interleukin-2, and Isotretinoin for Neuroblastoma. New England Journal of Medicine 2010;363:1324–34Voeller J, Erbe AK, Slowinski J, Rasmussen K, Carlson PM, Hoefges A, et al. Combined innate and adaptive immunotherapy overcomes resistance of immunologically cold syngeneic murine neuroblastoma to checkpoint inhibition. Journal for Immunotherapy of Cancer 2019;7:13

Sign in / Sign up

Export Citation Format

Share Document