scholarly journals Immune system derived from homeostatic proliferation generates normal CD8 T-cell memory but altered repertoires and diminished heterologous immune responses

Blood ◽  
2008 ◽  
Vol 112 (3) ◽  
pp. 680-689 ◽  
Author(s):  
Sue-Jane Lin ◽  
Alex T. Chen ◽  
Raymond M. Welsh
Keyword(s):  
T Cells ◽  
Immune System ◽  
T Cell ◽  
Immune Responses ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Homeostatic Proliferation ◽  
Memory Cells ◽  
Cell Repertoire ◽  
Cell Responses

AbstractThe host responds to lymphopenic environments by acute homeostatic proliferation of T lymphocytes, which acquire phenotypes similar to memory cells. Using T-cell knockout (KO) mice adoptively reconstituted with splenocytes from immunologically naive mice, we examined the immune responses of an immune system derived from homeostatically proliferating (HP) T cells. HP cells mounted relatively normal acute CD8 T-cell responses to lymphocytic choriomeningitis virus (LCMV), but with altered T-cell receptor (TCR) repertoires, and they became functional memory cells capable of recall responses. Although homeostatic proliferation does not normally fully restore T-cell numbers, the CD8+ T-cell pool was completely restored in T-cell KO mice after LCMV infection. CD4 T-cell responses were lower and not fully restored but seemed sufficient to allow for complete differentiation of CD8 memory T cells. The LCMV-immune HP mouse had an immune repertoire heavily biased with LCMV epitope-specific T cells with oligoclonal expansions. LCMV-immune HP mice had reduced cross-reactive and non–cross-reactive CD8 T-cell responses when challenged with a T cell–cross-reactive virus. Thus, whereas an HP immune system is capable of mounting relatively normal acute and memory CD8 T-cell responses, the narrowing of the T-cell repertoire may reduce immune responses to subsequently encountered pathogens.

scholarly journals TLR9 and Dendritic Cells Are Required for CD8+ T Cell Responses to the AAV Capsid

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 552-552 ◽  
Author(s):  
Geoffrey L. Rogers ◽  
Roland W Herzog
Keyword(s):  
Pattern Recognition ◽  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Cd8 T Cells ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
T Cell Response ◽  
Post Injection ◽  
Cell Responses

Abstract CD8+ T cell responses to the adeno-associated virus (AAV) capsid have posed a significant barrier to transduction in clinical trials of AAV-mediated gene therapy for hemophilia B, as reactivation of a memory CTL response to the capsid is capable of eliminating transduced hepatocytes in the absence of immunosuppression. Recently, it has been suggested that innate immune responses induced by the toll-like receptor (TLR) pathway can influence the development of adaptive immune responses to AAV-mediated gene transfer. In particular, reports have implicated TLR2 (AAV capsid), TLR9 (AAV genome), and MyD88 (downstream signaling adaptor of both these TLRs). Herein, we have used a modified AAV2 with an insertion of the immunodominant MHC class I epitope of ovalbumin into the capsid (AAV2-SIINFEKL) to study the mechanism of CD8+ T cell responses to the AAV capsid. Using an H2-Kb-SIINFEKL tetramer reagent, we determined that anti-capsid CD8+ T cell responses depended on the TLR9-MyD88 pathway. While the frequency of circulating capsid-specific CD8+ T cells peaked around 7-10 days post-injection and subsided after about 21 days in wild type (WT) mice, tetramer-positive cells were not detected in TLR9-/- or MyD88-/- mice. The kinetics and magnitude of the response was unaltered in TLR2-/- mice. Mice deficient in STING, a downstream adaptor of multiple cytoplasmic DNA sensing pathways, also developed comparable capsid-specific CD8+ T cell frequencies to WT mice, suggesting that this is not a general effect of pattern recognition of DNA. Interestingly, the frequency of capsid-specific CD8+ T cells was not reduced in AP3-/- mice, which are deficient in type I IFN signaling downstream of TLR9. Adoptively transferred OVA-specific OT-1 T cells proliferated in WT but not TLR9-/- mice that received AAV2-SIINFEKL, confirming the importance of TLR9. The effect was antigen-specific, as OT-1 cells in WT mice that received AAV2 lacking SIINFEKL showed minimal proliferation comparable to TLR9-/- mice. In addition to pattern-recognition receptors, we also assessed the role of antigen-presenting cells in the CD8+ T cell response to capsid. The formation of capsid-specific CD8+ T cells was unaltered in mice that received gadolinium chloride to inactivate macrophages, or in B cell-deficient μMT mice. Depletion of B cells in WT mice prior to vector administration also failed to affect the anti-capsid CD8+ T cell response. However, transient depletion of dendritic cells (DCs) in CD11c-DTR mice resulted in a delayed development of capsid-specific CD8+ T cells. Seven days post-injection, DC-depleted mice had a significantly reduced frequency of tetramer-positive CD8+ T cells which recovered to normal by 10 days, likely due to the repopulation of DCs before the input capsid was completely cleared. Overall, our results show that TLR9 signaling, most likely in DCs, is required for the formation of de novo anti-capsid CD8+ T cell responses. Disclosures Herzog: Genzyme: AAV-FIX technology Patents & Royalties.

Effect of epitopes derived from the mutated region of cytoplasmatic nucleophosmine 1 (NPM1) on CD4+ and CD8+ T-cell responses in patients with acute myeloid leukemia.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 6567-6567
Author(s):  
Jochen Greiner ◽  
Yoko Ono ◽  
Susanne Hofmann ◽  
Vanessa Schneider ◽  
Anita Schmitt ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Healthy Volunteers ◽  
Cd4 T Cells ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Chromium Release ◽  
Cell Responses ◽  
Hla Dr

6567 Background: Mutations of the nucleophosmin gene (NPM1mut) are one of the most frequent molecular alterations in AML and constitute an important prognostic marker. The impact of NPM1mut on leukemogenesis and progression remains to be elucidated. Immune responses against NPM1mut might contribute to the favourable prognosis of AML patients with NPM1mut. Therefore, we examined T cell responses against NPM1mut. Methods: NPM1 wildtype as well as NPM1mut were screened for HLA-A*0201 binding T cell epitopes with the help of different algorithm programs. Ten peptides with most favourable characteristics were tested with ELISpot analysis for interferon-γ and granzyme B in 33 healthy volunteers and 30 AML patients. Tetramer assays against most interesting epitopes were performed and chromium release assays were used to show the cytotoxicity of peptide-specific CD8+ T cells. Moreover, HLA-DR-binding epitopes were used to test the role of CD4+ T cells in NPM1 immunogenicity. Results: Two epitopes (#1 and #3) derived from NPM1mut induced CD8+ T cell responses in a high frequency. In healthy volunteers, immune responses were detected in 39%/18% against #1 and #3, and in 33%/44% of NPM1mut AML patients against #1 and #3. NPM1-peptide primed effector T cells showed specific lysis of pulsed T2 cells as well as leukemic blasts in chromium release assays. In tetramer assays a significant CD8+ T cell population could be detected. To obtain a robust and continuous T cell reaction, the help of CD4+ T cells is indispensable. Therefore, we investigated the increase of CD8+ T cell responses by the activation of CD4+ T cells stimulated with longer peptides called overlapping peptides (OL). Potent HLA-DR epitopes were predicted and several favourable peptides (OL 1 to 8) were synthesized. OL8 showed favourable results to activate both CD8+ and CD4+ T cells. Conclusions: Taken together, NPM1mut represents a candidate for immunotherapeutic approaches and we hypothesize that it is also potentially involved in immunogenic rejection of NPM1mut leukemic blasts. Therefore, NPM1mut is a promising target structure for specific immunotherapies in AML patients.

T Cell Responses Directed Against HLA A*0201-Restricted Epitopes Derived from WT1 Are Readily Identifiable in Patients with AML and CML, but Not in Patients with ALL.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2526-2526
Author(s):  
Katayoun Rezvani ◽  
Jason Brenchley ◽  
David Price ◽  
Yasemin Kilical ◽  
Matthias Grube ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Mhc Class I ◽  
Cd8 T Cells ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Cell Responses ◽  
Healthy Donors ◽  
Myeloid Leukemias

Abstract The WT1 gene contributes to leukemogenesis and all adult ALL, AML and CML express WT1 RNA by quantitative real-time reverse transcription polymerase chain reaction (qPCR) techniques. WT1 may therefore be a useful antigenic target for immunotherapy. Four HLA-A*0201-restricted WT1 T cell epitopes have been identified: Db126 (RMFPNAPYL), WH187 (SLGEQQYSV), WT37-45 (VLDFAPPGA) and WT235 (CMTWNQMNL), but only Db126 has been extensively studied in myeloid leukemias. Here, we sought CD8+ T cells directed against these epitopes in 12 healthy SCT donors, 6 patients with AML, 8 with, CML and 6 with ALL prior to SCT. All patients tested with myeloid or lymphoid leukemias expressed MHC class I, B7.1 and WT1. To detect very low frequencies of WT1-specific CD8+ T cells, we used qPCR for interferon-g (IFN-g) mRNA. After isolation, 106 CD8+ T cells were stimulated with C1R-A2 cells (MHC class I-defective LCL cells transfected with HLA-A*0201) loaded with test peptides at concentrations of 0.1, 1 and 10 mM to determine their functional avidity. CD8+ T cells were also stimulated with CMV pp65 (positive control) and gp100 (209-2M) (negative control) peptides. After 3 hr coculture, cells were harvested for RNA extraction and cDNA synthesis. qPCR was performed for IFN-g mRNA and normalized to copies of CD8 mRNA from the same sample. Parallel assays using tetramers demonstrated that the IFN-g copy number was linearly related to the frequency of tetramer-binding T cells, sensitive to frequencies of 1 responding CD8+ T cell/100 000 CD8+ T cells. A positive response was defined as a threshold of 100 or more IFN-g mRNA copies/104 CD8 copies and a stimulation index (SI) of 2 or more, where SI = IFN-g mRNA copies/104 CD8 copies in peptide pulsed/unpulsed cultures. Responses to at least one WT1 peptide were detected in 5/8 CML patients, 4/6 patients with AML and 7/12 healthy donors. Notably, a response was not elicited to WT1 in any of the 6 patients with ALL, despite evidence of immune competence as shown by a normal CMV response. Five of five CML responders and 3/4 AML responders recognized 2 or more WT1 epitopes, while the 7 healthy donors recognized only one WT1 epitope. The range of IFN-g mRNA copies/104 CD8 copies was 289–13584, 418–45891 and 160–2683 for CML, AML and healthy donors respectively. WT1-specific tetramer-positive CD8+ T cells displayed both central memory (CD45RO+CD27+CD57−) and terminally differentiated effector memory phenotypes (CD45RO-CD27−CD57+). As multiple WT1-derived epitopes can be targeted simultaneously, it is likely that T cell response to WT1 is polyclonal. These results are important because the presence of memory WT1 responses in patients with myeloid leukemias and healthy individuals should favor vaccination as a means to expand immune responses to leukemia in the autologous and allogeneic transplant setting. Furthermore, the presence of CD8+ T cell responses to multiple WT1 epitopes should favor robust polyclonal immune responses to leukemia. However, failure to detect CD8+ T cell responses to WT1 in ALL patients suggests that WT1 may not be a useful antigen to target for immunotherapeutic purposes in this patient group.

scholarly journals Mutated regions of nucleophosmin 1 elicit both CD4+ and CD8+ T-cell responses in patients with acute myeloid leukemia

Blood ◽  
2012 ◽  
Vol 120 (6) ◽  
pp. 1282-1289 ◽  
Author(s):  
Jochen Greiner ◽  
Yoko Ono ◽  
Susanne Hofmann ◽  
Anita Schmitt ◽  
Elmar Mehring ◽  
...  
Keyword(s):  
T Cells ◽  
Acute Myeloid Leukemia ◽  
T Cell ◽  
Immune Responses ◽  
Cd4 T Cells ◽  
Myeloid Leukemia ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Cell Responses ◽  
Acute Myeloid

Abstract Mutations in the nucleophosmin gene (NPM1mut) are one of the most frequent molecular alterations in acute myeloid leukemia (AML), and immune responses may contribute to the favorable prognosis of AML patients with NPM1mut. In the present study, we were able to demonstrate both CD4+ and CD8+ T-cell responses against NPM1mut. Ten peptides derived from wild-type NPM1 and NPM1mut were subjected to ELISPOT analysis in 33 healthy volunteers and 27 AML patients. Tetramer assays against the most interesting epitopes were performed and Cr51-release assays were used to show the cytotoxicity of peptide-specific T cells. Moreover, HLA-DR–binding epitopes were used to test the role of CD4+ T cells in NPM1 immunogenicity. Two epitopes (epitopes #1 and #3) derived from NPM1mut induced CD8+ T-cell responses. A total of 33% of the NPM1mut AML patients showed immune responses against epitope #1 and 44% against epitope #3. Specific lysis of leukemic blasts was detected. To obtain robust immune responses against tumor cells, the activation of CD4+ T cells is crucial. Therefore, overlapping (OL) peptides were analyzed in ELISPOT assays and OL8 was able to activate both CD8+ and CD4+ T cells. The results of the present study show that NPM1mut induces specific T-cell responses of CD4+ and CD8+ T cells and therefore is a promising target for specific immunotherapies in AML.

scholarly journals AAV Vector Dose Determines TLR9 Dependence of CD8+ T Cell Response to Transgene Product

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 3-3
Author(s):  
Ning Li ◽  
Thais Bertolini ◽  
Roland W Herzog
Keyword(s):  
T Cells ◽  
T Cell ◽  
Gene Transfer ◽  
Immune Responses ◽  
Cell Response ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
T Cell Response ◽  
Innate Immune ◽  
Cell Responses

Adeno-associated viral (AAV) vectors are currently evaluated in multiple Phase III clinical trial for the treatment of hemophilia and neuromuscular disorders. A major concern is the potential for immune responses. Viral vectors are initially sensed by the innate immune system, which shapes subsequent adaptive immune responses. Particularly, toll-like receptors (TLRs) have been reported as major sensors of pathogens during innate immune response. TLRs recognize pathogen-associated molecular patterns (PAMPs). Our previous studies found that cross-priming of AAV capsid-specific CD8+ T cells depended on TLR9-MyD88 pathway. TLR9 is an endosomal DNA receptor that responds most potently to unmethylated CpG motifs as found in bacterial and viral DNA. Similarly, others documented TLR9-dependent CD8+ T cell responses against non-secreted transgene products such as LacZ and hemagglutinin upon muscle-directed AAV gene transfer. Similarly, we published that CD8+ T cell responses to a secreted ovalbumin (ova) transgene product were substantially reduced (although not entirely eliminated) upon muscle gene transfer in TLR9-deficient mice [J Innate Immun. 7:302-14]. For those studies, we had used a self-complementary scAAV genomes, which we found to more strongly activate TLR9 than conventional single-stranded ssAAV vectors. Here, we performed intramuscular injections of 3 doses of ssAAV1-CMV-ova vector (2X1010, 2X1011 and1X1012 vg) in wild-type (WT), TLR9-/-, or MYD88-/- C57BL/6 mice. Using MHC tetramer (H2-Kb -SIINFEKL), ova-specific CD8+ T cell frequencies were monitored in peripheral blood for up to 6 weeks. As expected from prior studies, TLR9-/- mice showed a substantially reduced response (1.2% tetramer+ of CD8) at the low dose when compared to WT (12% tetramer+ of CD8) animals (p<0.0001, n=5/group). To our surprise, CD8+ T cell responses were similar in TLR9-/- and WT mice at the 2 higher doses. TLR9-/- mice displayed 16% and 3.3% tetramer+ of CD8 frequencies at the median and the high doses, respectively; which was comparable to WT mice, where 15% and 4.8% tetramer+ of CD8 frequencies were observed (n=5/group). Therefore, sensing of the AAV genome by TLR9 is more critical for the CD8+ T cell response to the secreted transgene product at lower vector doses (possibly related to the lower levels of transgene expression). Interestingly, transgene product-specific CD8+ T cell responses were much reduced in MyD88-/- mice, in which 0.2% and 1.7% tetramer+ of CD8 frequencies were found for low and median doses. Therefore, an alternative signaling pathway that includes the MyD88 adaptor molecule likely exists that is more critical than TLR9 above a certain level of expression. The reduced strength of the CD8+ T cell response seen at the highest vector dose compared to the medium dose may be explained by a transient increase in FoxP3+ Treg and in PD-1+ T cells that we observed 1 week after gene transfer and that was significantly greater at the highest vector dose. In related experiments, we performed intramuscular gene transfer using a ssAAV1-EF1a-FIX vector in hemophilia B mice (C3H/HeJ F9-/-, 1x1011 vg/mouse). Here, we used either a vector with native sequences or with an expression cassette that was entirely devoid of CpG motifs (and there stimulates TLR9 less effectively). CpG depletion did not have substantial effects on antibody formation against human FIX or the viral capsid. However, CD8+ T cell infiltrates in skeletal muscle were markedly reduced but not entirely eliminated when tissue sections were examined 1 month after gene transfer. In conclusion, TLR9 signaling is one important factor in the activation of transgene product-specific CD8+ T cells in AAV gene transfer, but other pathways exist that may be more critical depending on vector dose or levels of expression. Disclosures Herzog: Takeda Pharmaceuticals: Patents & Royalties.

scholarly journals A Paradigmatic Interplay between Human Cytomegalovirus and Host Immune System: Possible Involvement of Viral Antigen-Driven CD8+ T Cell Responses in Systemic Sclerosis

Viruses ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 508 ◽  
Author(s):  
Maria-Cristina Arcangeletti ◽  
Clara Maccari ◽  
Rosanna Vescovini ◽  
Riccardo Volpi ◽  
Dilia Giuggioli ◽  
...  
Keyword(s):  
T Cells ◽  
Systemic Sclerosis ◽  
T Cell ◽  
Immune Responses ◽  
Human Cytomegalovirus ◽  
Healthy Subjects ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Cell Responses

Human cytomegalovirus (HCMV) is a highly prevalent opportunistic agent in the world population, which persists as a latent virus after a primary infection. Besides the well-established role of this agent causing severe diseases in immunocompromised individuals, more recently, HCMV has been evoked as a possible factor contributing to the pathogenesis of autoimmune diseases such as systemic sclerosis (SSc). The interplay between HCMV and immune surveillance is supposed to become unbalanced in SSc patients with expanded anti-HCMV immune responses, which are likely involved in the exacerbation of inflammatory processes. In this study, blood samples from a cohort of SSc patients vs. healthy subjects were tested for anti-HCMV immune responses (IgM, IgG antibodies, and T cells to peptide pools spanning the most immunogenic HCMV proteins). Statistically significant increase of HCMV-specific CD8+ T cell responses in SSc patients vs. healthy subjects was observed. Moreover, significantly greater HCMV-specific CD8+ T cell responses were found in SSc patients with a longer disease duration and those with higher modified Rodnan skin scores. Given the known importance of T cells in the development of SSc and that this virus may contribute to chronic inflammatory diseases, these data support a relevant role of HCMV-specific CD8+ T cell responses in SSc pathogenesis.

scholarly journals Enhancement of HIV-1 Env-Specific CD8 T Cell Responses Using Interferon-Stimulated Gene 15 as an Immune Adjuvant

2020 ◽  
Vol 95 (2) ◽  
pp. e01155-20
Author(s):  
Carmen Elena Gómez ◽  
Beatriz Perdiguero ◽  
Michela Falqui ◽  
María Q. Marín ◽  
Martina Bécares ◽  
...  
Keyword(s):  
Immune Response ◽  
Immune System ◽  
T Cell ◽  
Immune Responses ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Cell Responses ◽  
Immune Adjuvant ◽  
Hiv 1

ABSTRACTInduction of the endogenous innate immune system by interferon (IFN) triggers the expression of many proteins that serve like alarm bells in the body, activating an immune response. After a viral infection, one of the genes activated by IFN induction is the IFN-stimulated gene 15 (ISG15), which encodes a ubiquitin-like protein that undergoes a reversible posttranslational modification (ISGylation). ISG15 protein can also act unconjugated, intracellularly and secreted, acting as a cytokine. Although ISG15 has an essential role in host defense responses to microbial infection, its role as an immunomodulator in the vaccine field remains to be defined. In this investigation, we showed that ISG15 exerts an immunomodulatory role in human immunodeficiency virus (HIV) vaccines. In mice, after priming with a DNA-ISG15 vector mixed with a DNA expressing HIV-1 gp120 (DNA-gp120), followed by a booster with a modified vaccinia virus Ankara (MVA) vector expressing HIV-1 antigens, both wild-type ISG15-conjugated (ISG15-wt) and mutant unconjugated (ISG15-mut) proteins act as immune adjuvants by increasing the magnitude and quality of HIV-1-specific CD8 T cells, with ISG15-wt providing better immunostimulatory activity than ISG15-mut. The HIV-1 Env-specific CD8 T cell responses showed a predominant T effector memory (TEM) phenotype in all groups. Moreover, the amount of DNA-gp120 used to immunize mice could be reduced 5-fold after mixing with DNA-ISG15 without affecting the potency and the quality of the HIV-1 Env-specific immune responses. Our study clearly highlights the potential use of the IFN-induced ISG15 protein as immune adjuvant to enhance immune responses to HIV antigens, suggesting that this molecule might be exploitable for prophylactic and therapeutic vaccine approaches against pathogens.IMPORTANCE Our study described the potential role of ISG15 as an immunomodulatory molecule in the optimization of HIV/AIDS vaccine candidates. Using a DNA prime–MVA boost immunization protocol, our results indicated an increase in the potency and the quality of the HIV-1 Env-specific CD8 T cell response. These results highlight the adjuvant potency of ISG15 to elicit improved viral antigen presentation to the immune system, resulting in an enhanced HIV-1 vaccine immune response. The DNA-ISG15 vector could find applicability in the vaccine field in combination with other nucleic acid-based vector vaccines.

scholarly journals Utility of Human Immunodeficiency Virus Type 1 Envelope as a T-Cell Immunogen

2007 ◽  
Vol 81 (23) ◽  
pp. 13125-13134 ◽  
Author(s):  
Viv Peut ◽  
Stephen J. Kent
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Immune Responses ◽  
T Cell Responses ◽  
Cd8 T Cell ◽  
Viral Escape ◽  
Cell Responses ◽  
Immunodeficiency Virus

ABSTRACT Human immunodeficiency virus (HIV)-specific CD8 T lymphocytes are important for the control of viremia, but the relative utility of responses to the various HIV proteins is controversial. Immune responses that force escape mutations that exact a significant fitness cost from the mutating virus would help slow progression to AIDS. The HIV envelope (Env) protein is subject to both humoral and cellular immune responses, suggesting that multiple rounds of mutation are needed to facilitate viral escape. The Gag protein, however, has recently been shown to elicit a more effective CD8 T-cell immune response in humans. We studied 30 pigtail macaques for their CD8 T-lymphocyte responses to HIV-1 Env and simian immunodeficiency virus (SIV) Gag following prime/boost vaccination and intrarectal challenge with simian-human immunodeficiency virus SHIVmn229. Eight CD8 Env-specific T-cell epitopes were identified and mapped in 10 animals. Animals that generated Env-specific CD8 T-cell responses had equivalent viral loads and only a modest advantage in retention of peripheral CD4 T lymphocytes compared to those animals without responses to Env. This contrasts with animals that generated CD8 T-cell responses to SIV Gag in the same trial, demonstrating superior control of viral load and a larger advantage in retention of peripheral CD4 T cells than Gag nonresponders. Mutational escape was common in Env but, in contrast to mutations in Gag, did not result in the rapid emergence of dominant escape motifs, suggesting modest selective pressure from Env-specific T cells. These results suggest that Env may have limited utility as a CD8 T-cell immunogen.

scholarly journals 413 GEN-009, a personalized neoantigen vaccine, elicits robust immune responses in individuals with advanced or metastatic solid tumors

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A438-A438
Author(s):  
Mara Shainheit ◽  
Devin Champagne ◽  
Gabriella Santone ◽  
Syukri Shukor ◽  
Ece Bicak ◽  
...  
Keyword(s):  
Clinical Trial ◽  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Solid Tumors ◽  
Ex Vivo ◽  
T Cell Responses ◽  
Checkpoint Blockade ◽  
T Cell Subsets ◽  
Cell Responses

BackgroundATLASTM is a cell-based bioassay that utilizes a cancer patient‘s own monocyte-derived dendritic cells and CD4+ and CD8+ T cells to screen their mutanome and identify neoantigens that elicit robust anti-tumor T cell responses, as well as, deleterious InhibigensTM.1 GEN-009, a personalized vaccine comprised of 4–20 ATLAS-identified neoantigens combined with Hiltonol®, harnesses the power of neoantigen-specific T cells to treat individuals with solid tumors. The safety and efficacy of GEN-009 is being assessed in a phase 1/2a clinical trial (NCT03633110).MethodsA cohort of 15 adults with solid tumors were enrolled in the study. During the screening period, patients received standard of care PD-1-based immunotherapies appropriate for their tumor type. Subsequently, patients were immunized with GEN-009 with additional doses administered at 3, 6, 12, and 24 weeks. Peripheral blood mononuclear cells (PBMCs) were collected at baseline, pre-vaccination (D1), as well as 29, 50, 92, and 176 days post first dose. Vaccine-induced immunogenicity and persistence were assessed by quantifying neoantigen-specific T cell responses in ex vivo and in vitro stimulation dual-analyte fluorospot assays. Polyfunctionality of neoantigen-specific T cells was evaluated by intracellular cytokine staining. Additionally, potential correlations between the ATLAS-identified profile and vaccine-induced immunogenicity were assessed.ResultsGEN-009 augmented T cell responses in 100% of evaluated patients, attributable to vaccine and not checkpoint blockade. Furthermore, neoantigen-induced secretion of IFNγ and/or TNFα by PBMCs, CD4+, and CD8+ T cells was observed in all patients. Responses were primarily from polyfunctional TEM cells and detectable in both CD4+ and CD8+ T cell subsets. Some patients had evidence of epitope spreading. Unique response patterns were observed for each patient with no apparent relationship between tumor types and time to emergence, magnitude or persistence of response. Ex vivo vaccine-induced immune responses were observed as early as 1 month, and in some cases, persisted for 176 days. Clinical efficacy possibly attributable to GEN-009 was observed in several patients, but no correlation has yet been identified with neoantigen number or magnitude of immune response.ConclusionsATLAS empirically identifies stimulatory neoantigens using the patient‘s own immune cells. GEN-009, which is comprised of personalized, ATLAS-identified neoantigens, elicits early, long-lasting and polyfunctional neoantigen-specific CD4+ and CD8+ T cell responses in individuals with advanced cancer. Several patients achieved clinical responses that were possibly attributable to vaccine; efforts are underway to explore T cell correlates of protection. These data support that GEN-009, in combination with checkpoint blockade, represents a unique approach to treat solid tumors.AcknowledgementsWe are grateful to the patients and their families who consented to participate in the GEN-009-101 clinical trial.Trial RegistrationNCT03633110Ethics ApprovalThis study was approved by Western Institutional Review Board, approval number 1-1078861-1. All subjects contributing samples provided signed individual informed consent.ReferenceDeVault V, Starobinets H, Adhikari S, Singh S, Rinaldi S, Classon B, Flechtner J, Lam H. Inhibigens, personal neoantigens that drive suppressive T cell responses, abrogate protection of therapeutic anti-tumor vaccines. J. Immunol 2020; 204(1 Supplement):91.15.

Sign in / Sign up

Export Citation Format

Share Document