Abstract PR6: Disrupting enhancers within the core epigenetic program of exhaustion improves T-cell responses and enhances tumor control

The depletion of eosinophils represents an efficient strategy to alleviate allergic asthma, but the consequences of prolonged eosinophil deficiency for human health remain poorly understood. We show here that the ablation of eosinophils severely compromises antitumor immunity in syngeneic and genetic models of colorectal cancer (CRC), which can be attributed to defective Th1 and CD8+ T cell responses. The specific loss of GM-CSF signaling or IRF5 expression in the eosinophil compartment phenocopies the loss of the entire lineage. GM-CSF activates IRF5 in vitro and in vivo and can be administered recombinantly to improve tumor immunity. IL-10 counterregulates IRF5 activation by GM-CSF. CRC patients whose tumors are infiltrated by large numbers of eosinophils also exhibit robust CD8 T cell infiltrates and have a better prognosis than patients with eosinophillow tumors. The combined results demonstrate a critical role of eosinophils in tumor control in CRC and introduce the GM-CSF–IRF5 axis as a critical driver of the antitumor activities of this versatile cell type.

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Host type I IFN signals are required for antitumor CD8+ T cell responses through CD8α+ dendritic cells

Journal of Experimental Medicine ◽

10.1084/jem.20101159 ◽

2011 ◽

Vol 208 (10) ◽

pp. 2005-2016 ◽

Cited By ~ 577

Author(s):

Mercedes B. Fuertes ◽

Aalok K. Kacha ◽

Justin Kline ◽

Seng-Ryong Woo ◽

David M. Kranz ◽

...

Keyword(s):

Dendritic Cells ◽

T Cell ◽

T Cell Responses ◽

Innate Immune ◽

Tumor Control ◽

Type I ◽

Immune Recognition ◽

Cell Responses ◽

Host Type ◽

T Cell Priming

Despite lack of tumor control in many models, spontaneous T cell priming occurs frequently in response to a growing tumor. However, the innate immune mechanisms that promote natural antitumor T cell responses are undefined. In human metastatic melanoma, there was a correlation between a type I interferon (IFN) transcriptional profile and T cell markers in metastatic tumor tissue. In mice, IFN-β was produced by CD11c+ cells after tumor implantation, and tumor-induced T cell priming was defective in mice lacking IFN-α/βR or Stat1. IFN signaling was required in the hematopoietic compartment at the level of host antigen-presenting cells, and selectively for intratumoral accumulation of CD8α+ dendritic cells, which were demonstrated to be essential using Batf3−/− mice. Thus, host type I IFNs are critical for the innate immune recognition of a growing tumor through signaling on CD8α+ DCs.

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303 Non-functional T cell responses in non-small cell lung cancer are induced during tumor antigen-specific T cell priming in the mediastinal lymph node

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2021-sitc2021.303 ◽

2021 ◽

Vol 9 (Suppl 3) ◽

pp. A326-A326

Author(s):

Brendan Horton ◽

Duncan Morgan ◽

Elen Torres-Mejia ◽

Maria Zagorulya ◽

Vidit Bhandarkar ◽

...

Keyword(s):

Lung Cancer ◽

T Cells ◽

T Cell ◽

Cd8 T Cells ◽

Lung Tumor ◽

T Cell Responses ◽

Cd8 T Cell ◽

Lung Tumors ◽

Tumor Control ◽

Cell Responses

BackgroundIn non-small cell lung cancer (NSCLC), response to checkpoint blockade therapy (CBT) is associated with tumor-infiltrating CD8+ T cells, but not all T cell-infiltrated tumors respond to CBT. The subgroup of T cell-infiltrated but CBT-resistant tumors has been clinically described as containing ”non-functional” T cell responses. Mechanisms governing the generation of non-functional T cell responses remain poorly understood, and treatment options for this subgroup are limited.MethodsWe utilized a transplantable, syngeneic murine NSCLC cell line derived from an autochthonous NSCLC driven by KrasG12D expression and p53 deletion (KP cell line) to model non-functional T cell responses. To study antigen-specific responses, we engineered KP cells to express the model CD8+ T cell antigen SIY for certain experiments. CBT consisted of combined anti-CTLA-4 and anti-PD-L1 therapy.ResultsOrthotopic KP lung tumors failed to respond to CBT, but KP flank tumors were controlled by CBT. Lung and flank tumors contained activated CD8+ T cells, providing a platform to compare functional and non-functional CD8+ T cell responses in NSCLC. Single-cell RNA sequencing revealed that lung tumor-infiltrating CD8+ T cells lacked effector and exhaustion molecules despite clonal expansion. Analysis of antigen-specific CD8+ T cells revealed that this lung cancer-specific T cell dysfunction was established during priming in lung-draining mediastinal lymph nodes (mLN) despite robust T cell proliferation. RNA sequencing and flow cytometry of antigen-specific CD8+ T cells found that T cells primed in the mLN underwent blunted effector differentiation characterized by a lack of effector molecules CD25, Granzyme B, and TIM-3, but retention of TCF-1. This phenotype persisted in lung tumors, consistent with our initial observations of absent effector and exhaustion molecule expression. Many CD8+ T cells from NSCLC patients expressed an analogous gene expression program distinct from T cell exhaustion. TCF-1+ CD8+ T cells in lung tumors did not mediate tumor control and failed to differentiate into effector cells after CBT. To investigate alternative therapeutic strategies of reinvigorating lung tumor-reactive T cells, we focused on IL-2 and IL-12, as expression of their receptors was reduced in mLN-primed T cells. Administering recombinant IL-2 and IL-12 was sufficient to restore effector T cell differentiation, induce lung tumor control, and significantly extend survival of lung tumor-bearing mice.ConclusionsOur results suggest that non-functional CD8+ T cell responses in NSCLC arise from failed effector T cell differentiation during priming. Transient combination therapy with IL-2 and IL-12 overcomes this dysfunctional state to induce protective T cell responses in CBT-resistant tumors.Ethics ApprovalAll mouse experiments were approved by MIT’s Committee on Animal Care (CAC) - DHHS Animal Welfare Assurance # D16-00078

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P03.01 High immunogenic VLP-based vaccines elicit new T cell specificities against melanoma neoantigens in mice

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2021-itoc8.24 ◽

2021 ◽

Vol 9 (Suppl 1) ◽

pp. A13.1-A13

Author(s):

C Aguilar-Gurrieri ◽

A Barajas ◽

A Pons-Grifols ◽

I Varela ◽

P Amengual-Rigo ◽

...

Keyword(s):

T Cell ◽

Immune Responses ◽

Therapeutic Vaccine ◽

T Cell Responses ◽

Advisory Board ◽

Tumor Control ◽

Vaccine Platform ◽

Anchor Residue ◽

Synonymous Mutations ◽

Cell Responses

BackgroundNeoantigens’ (neoAg) identification, which determines T-cell responses against tumors, has fostered the development of personalized vaccines with promising results. While the ranking of the most immunogenic neoAg can be addressed using predictive techniques, their formulation as vaccines needs to be improved. To maximize their therapeutic potential, optimal neoAg-based vaccines should be manufactured in a superb delivery platform that enhances robust new immune responses, able to bypass thymic tolerance and the humoral immunosuppressive microenvironment. These novel T cell responses generated at the periphery will not be exhausted, opposite to TILs. We aim to develop a highly immunogenic vaccine platform, based on engineered HIV-derived Virus-Like Particles (VLP) expressing approximately 2500 copies of each selected neoAg. We tested different neoAgs loaded VLPs (neoVLP) in a melanoma mouse model to evaluate their capability to generate new immunogenic specificities.Material and MethodsSpecific non-synonymous mutations from B16F10 cells were identified, selected and used to generate a list of prioritized peptides. NeoAgs were classified as: Tier1, acquiring a mutation that creates an anchor residue to the MHC-I, not present in the WT peptide; Tier2, acquiring a mutation in a position that largely impacts contact with the TCR respect to WT; and Tier3, acquiring a mutation in the TCR contact region but inducing a less drastic change than in Tier2. Frame shift (FS) mutations, expected to be highly immunogenic, were also included.Thirteen to fifteen selected neoAgs from each group were loaded on highly immunogenic neoVLPs. Their immunogenicity was evaluated in C57bl/6 mice by immunization with a neoVLP-coding plasmid DNA (prime) and purified neoVLPs as soluble particles (boost). Splenocytes were used to evaluate neoAg-specific T cell responses.ResultsWe have successfully generated and purified neoVLPs, exposing neoAgs from all groups by transient transfection of Expi293 cells. Protein integrity and VLP morphology were confirmed by western blot and cryo-EM. When used for immunization assays, neoVLPs, containing neoAgs from Tier2, Tier3 and FS groups, were capable of generating humoral responses against viral proteins and T cell responses against neoAgs present in the neoVLP. B16F10 inoculated animals, but not vaccinated, did not develop detectable T cell responses against neoAgs present in any tested neoVLP, suggesting that the vaccination with neoVLPs promoted new specificities against selected neoAgs that might contribute to tumor control and eradication.ConclusionOur data show that the neoVLPs promote the generation of new antitumor-specific immune responses against selected neoepitopes, suggesting that neoVLPs vaccination could be an alternative to current therapeutic vaccine approaches and a promising candidate for future personalized immunotherapy.Disclosure InformationC. Aguilar-Gurrieri: None. A. Barajas: None. A. Pons-Grifols: None. I. Varela: None. P. Amengual-Rigo: None. R. Farriol: None. M. Vazquez: None. R. Lepore: None. C. Anjos-Souza: None. J. Blanco-Heredia: None. L. de Mattos-Arruda: None. V. Guallar: None. A. Valencia: None. B. Clotet: F. Consultant/Advisory Board; Significant; Albajuna Therapeutics. J. Carrillo: Other; Significant; Albajuna Therapeutics. J. Blanco: F. Consultant/Advisory Board; Significant; Albajuna Therapeutics.

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Microwave ablation enhances tumor-specific immune response in patients with hepatocellular carcinoma

Cancer Immunology Immunotherapy ◽

10.1007/s00262-020-02734-1 ◽

2020 ◽

Author(s):

Katharina Leuchte ◽

Elena Staib ◽

Martin Thelen ◽

Philipp Gödel ◽

Axel Lechner ◽

...

Keyword(s):

Hepatocellular Carcinoma ◽

Immune Response ◽

T Cell ◽

Immune Responses ◽

Thermal Ablation ◽

Microwave Ablation ◽

T Cell Responses ◽

Tumor Control ◽

Free Survival ◽

Cell Responses

Abstract Thermal ablative therapies are standard treatments for localized hepatocellular carcinoma (HCC). In addition to local tumor destruction, ablation leads to abscopal effects in distant lesions most likely mediated by an anti-tumor immune response. Although microwave ablation (MWA) is increasingly substituting other ablative techniques, its systemic immunostimulatory effects are poorly studied. We analyzed tumor-specific immune responses in peripheral blood of HCC patients after thermal ablation with regard to T cell responses and disease outcome. While comprehensive flow cytometric analyses in sequential samples of a prospective patient cohort (n = 23) demonstrated only moderate effects of MWA on circulating immune cell subsets, fluorospot analyses of specific T cell responses against seven tumor-associated antigens (TTAs) revealed de-novo or enhanced tumor-specific immune responses in 30% of patients. This anti-tumor immune response was related to tumor control as Interferon-y and Interleukin-5 T cell responses against TAAs were more frequent in patients with a long-time remission (> 1 year) after MWA (7/16) compared to patients suffering from an early relapse (0/13 patients) and presence of tumor-specific T cell response (IFN-y and/or IL-5) was associated to longer progression-free survival (27.5 vs. 10.0 months). Digital image analysis of immunohistochemically stained archival HCC samples (n = 18) of patients receiving combined MWA and resection revealed a superior disease-free survival of patients with high T cell abundance at the time of thermal ablation (37.4 vs. 13.1 months). Our data demonstrates remarkable immune-related effects of MWA in HCC patients and provides additional evidence for a combination of local ablation and immunotherapy in this challenging disease.

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Listeria monocytogenes personalized cancer vaccines drive therapeutic immune responses to cancer derived neoantigens

10.1101/2020.05.11.088930 ◽

2020 ◽

Author(s):

Brandon Coder ◽

Olga Pryshchep ◽

Dipti Kelkar ◽

Elena Filippova ◽

Xiaoming Ju ◽

...

Keyword(s):

T Cells ◽

Listeria Monocytogenes ◽

T Cell ◽

Immune Responses ◽

Tumor Growth ◽

T Cell Responses ◽

Absolute Number ◽

Tumor Control ◽

Mouse Tumor ◽

Cell Responses

AbstractBackgroundRecent advances in the field of cancer immunotherapy have identified CD8+ T cell responses against tumor-specific mutations as a key driver of tumor regression and overall survival. ADXS-NEO is a personalized Listeria monocytogenes (Lm)-based immunotherapy designed to target a patient’s mutation-derived tumor-specific neoantigens. The objective of this study is to demonstrate the feasibility of using the ADXS-NEO platform to target tumor-specific point mutations and control tumor growth by generating neoantigen-specific T cell responses using a pre-clinical mouse tumor model.MethodsWhole-exome sequencing of the MC38 mouse tumor cell line identified 2870 unique non-synonymous mutations. The netMHCcons algorithm was used to predict 137 potential neoantigens. We validated 20 immunogenic neoantigens either by peptide immunization followed by ELISPOT or by the presence of CD8+ T cells recognizing the neoantigen peptide following checkpoint inhibitor treatment. Two ADXS-NEO vectors were constructed; Lm20, targeting 20 validated immunogenic neoantigens, and Lm19, targeting most of the non-validated NSMs.ResultsBoth Lm19 & Lm20 significantly slowed tumor growth in C57BL/6 mice compared to control. An accumulation of ADXS-NEO-specific TILs was observed in tumor bearing mice treated with either Lm19 or Lm20. Examination of the tumor microenvironment in Lm19 or Lm20 treated mice revealed a decrease in the frequency and absolute number of Tregs, TAMs, MDSCs, and PD1high exhausted CD8+ T cells as well as an increase in the frequency and absolute number of effector CD8+ T cells, relative to control.ConclusionADXS-NEO is a potent immunotherapy capable of driving immune responses against tumor-specific mutations and leading to tumor control in mice.

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