bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract A71: Resistance mechanisms limiting the immunostimulatory and antitumor activity of anti-CSF-1 receptor-mediated macrophage depletion
Authors: Skrzypczynska Katarzyna M. , O'Brien Sarah A. , Belmontes Brian , Tan Hong , Orf Jessica , Lu Daniel , Driver Ian , Egen Jackson G. 
Published: June 2021

Abstract
Tumor-associated macrophages (TAMs) are present within the stroma of most solid tumors where they contribute to disease progression through production of tumor and angiogenic growth factors, extracellular matrix remodeling, and suppression of immune responses. As such, depletion of tumor-associated macrophages, for instance through the use of blocking antibodies against the CSF-1 receptor (CSF1R), has been widely explored as a therapeutic approach to both inhibit tumor growth/metastasis and stimulate antitumor immune responses. In the context of immunotherapy, multiple preclinical murine studies have demonstrated that anti-CSF1R meditated macrophage depletion can promote antitumor T-cell responses, synergizing with immune checkpoint inhibitor therapy, such as PD1 blockade, and leading to tumor regression. However, some tumor models appear resistant to these beneficial effects of CSF1R blockade. In order to define potential mechanisms of resistance to CSF1R inhibitors, we evaluated the effects of anti-CSF1R treatment in mice bearing subcutaneous Renca renal cell adenocarcinoma tumors. Despite robust macrophage depletion, this model shows only a modest decrease in tumor volume and minimal effector T-cell recruitment or activation in response to anti-CSF1R therapy. Comprehensive flow cytometry-based immunophenotyping and single-cell RNA sequencing on immune cells isolated from anti-CSF1R- and isotype control-treated Renca tumors revealed shifts in gene expression patterns related to vascular remodeling, hypoxic responses, and enhanced regulatory T-cell activity. These studies indicate macrophage depletion may, under some conditions, have negative effects on antitumor immune responses that could limit the clinical benefit of this therapeutic approach.
Citation Format: Katarzyna M. Skrzypczynska, Sarah A. O'Brien, Brian Belmontes, Hong Tan, Jessica Orf, Daniel Lu, Ian Driver, Jackson G. Egen. Resistance mechanisms limiting the immunostimulatory and antitumor activity of anti-CSF-1 receptor-mediated macrophage depletion [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A71.
Abstract A94: Identification of potent, insurmountable A2a antagonists for modulation of the tumor microenvironment
Authors: Pettipher Roy , White Jonathan , Patel Viral , Moulton Ben , Pores Soraya , Assuncao Marta , Gherbi Karolina , Sengmany K. , Rosethorne Elisabeth , Finan Peter , Charlton Steven , McCarthy Clive 
Published: June 2021

Abstract
Adenosine is elevated in the tumor microenvironment and plays a critical role in suppressing T-cell function through high-affinity interaction with the A2a receptor. Genetic deficiency of A2a in mice is associated with enhanced cytotoxic responses and reduced tumor burden in syngeneic models. These effects are mimicked by small-molecule A2a antagonists and some of these compounds are currently being evaluated in clinical trials for the treatment of solid tumors, particularly in combination with checkpoint inhibitors. However, high levels of adenosine in the tumor microenvironment may pose a challenge for the development of A2a antagonists unless they possess the appropriate pharmaceutical profile. A series of potent antagonists were identified that displayed sub-nanomolar binding activity and selectivity over other adenosine receptors. Within this series, compounds were identified that maintained activity across a broad range of adenosine concentrations. These compounds behaved as insurmountable antagonists in a functional assay utilizing CHO cells expressing human recombinant A2a and displayed slow dissociation kinetics in a FRET-based receptor-binding assay. This series is exemplified by ARX1598, which had a Ki of 0.08nM in the A2a receptor-binding assay and an estimated KB of 0.06 nM in the recombinant cell-based assay. Schild analysis revealed that this compound behaved as an insurmountable antagonist and had a markedly slower off-rate than comparator competitive antagonists. The adenosine receptor agonist NECA suppressed cytokine production by peripheral blood mononuclear cells activated by anti-CD3/anti-CD28. ARX1598 prevented NECA-mediated suppression of cytokine production by human peripheral blood mononuclear cells (EC50= 6 nM) and prevented elevation of pCREB induced by high concentrations of NECA (3μM) in human whole blood (IC50=22nM). The potency of ARX1598 in the human whole blood assay was 50-100 times higher than comparator compounds currently being evaluated in cancer trials. These data illustrate that it is possible to identify potent compounds that have the potential to modulate the adenosine pathway in the tumor microenvironment.
Citation Format: Roy Pettipher, Jonathan White, Viral Patel, Ben Moulton, Soraya Pores, Marta Assuncao, Karolina Gherbi, K. Sengmany, Elisabeth Rosethorne, Peter Finan, Steven Charlton, Clive McCarthy. Identification of potent, insurmountable A2a antagonists for modulation of the tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A94.
Abstract A97: The inhibitory receptor NKG2A acts as a checkpoint on CD8 T cells in the context of cancer vaccines
Authors: van Hall Thorbald , van Montfoort Nadine , Borst Linda , Korrer Michael J. , Kim Young , André Pascale , Wagtmann Nicolai , Piersma Sytse , van der Burg Sjoerd H. 
Published: June 2021

Abstract
We previously demonstrated that high HLA-E expression in ovarian carcinoma and NSCLC may neutralize the survival benefit of T-cell infiltration, suggesting NKG2A could represent an immune checkpoint. Here, we demonstrate higher frequencies of NKG2A+CD8+ T cells in TIL samples obtained from human HNSCC biopsies in patients with measurable immune reactivity to HPV16-viral antigens. CyTOF analysis suggested that this T-cell subset harbored an CD103+ effector phenotype. In mouse tumor models, therapeutic cancer vaccines increased the frequency of NKG2A+-positive CD8+ TIL up to 80%. Expression of Qa-1, the mouse homologue of HLA-E, on tumor cells also increased after cancer vaccinations. In vitro studies revealed that upregulation of Qa-1 was mediated by T cell-derived IFNγ. Blockade of this inhibiting NKG2A-Qa-1 axis by antibody improved the T-cell mediated rejection of tumors and, in addition, genetic knockdown of Qa-1 in three different tumor models recapitulated this finding. Blocking of NKG2A as a stand-alone treatment was not effective, indicating that NKG2A constitutes an adaptive resistance mechanism in response to CD8 T-cell activation. In conclusion, NKG2A is enriched on CD8+ TIL and functions as an immune checkpoint that restrains therapeutic efficacy of cancer vaccines.
Citation Format: Thorbald van Hall, Nadine van Montfoort, Linda Borst, Michael J. Korrer, Young Kim, Pascale André, Nicolai Wagtmann, Sytse Piersma, Sjoerd H. van der Burg. The inhibitory receptor NKG2A acts as a checkpoint on CD8 T cells in the context of cancer vaccines [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A97.
Abstract B09: Targeting scavenger receptors for immunotherapy of cancer
Authors: Boura Vanessa F. , Tyystjärvi Sofia , Oliynyk Ganna , Arsenian-Henriksson Marie , Karlsson Mikael C.I. , Sohn Silke 
Published: June 2021

Abstract
Background: Tumor-associated macrophages (TAM) play an important role in tumor-promoting inflammation and have been associated with poor prognosis in many human cancers. Recently, we showed that class A scavenger receptor MARCO is a specific marker for the immune-suppressive tumor-promoting TAM subtype in different tumor models. Targeting MARCO by monoclonal antibodies (Ab) could reprogram the protumorigenic TAM towards a proinflammatory phenotype with antitumor activity, leading to decreased tumor growth and metastases formation in three different mouse tumor models.
Aim(s): The current immunotherapies are estimated to treat less than 50% of all cancers; therefore, it is of high importance to develop new targets and combinatorial therapies. In this study, we aim to define the role of scavenger receptor MARCO on TAM in more detail and the mechanisms of how targeting MARCO by monoclonal Ab modulates macrophage phenotype and tumor microenvironment. Moreover, we are investigating how it can be used as a possible anticancer therapeutic approach used as single or combinatorial treatment.
Results: Our recent data demonstrate that using anti-MARCO Ab in combination with other immune checkpoint inhibitors, such as anti-CTLA-4 Ab, further decreases the tumor volume by 40-50% in the B16 melanoma model. For example, different checkpoint Ab combined with anti-MARCO Ab shows a reduction from average tumor volume 500mm3 in single treatments to 250mm3 (p=0.0101) in the combinatorial treatment. Currently, we are investigating what happens in the tumor microenvironment on a cellular level after using the different combinatorial treatments. Moreover, we see increased ATP release of MARCO+ macrophages in vitro after engagement of MARCO as well as enhanced glycolysis in anti-MARCO Ab treated macrophages compared to the control group.
Conclusion: Checkpoint inhibitors targeting T cells are already used in the clinics and the anti-MARCO Ab targeting TAM is a promising candidate to use in combination with checkpoint inhibitors to even further increase the survival rate of patients. The understanding of MARCO signaling and how this leads to a shift towards proinflammatory macrophages would not just benefit the field of basic macrophage biology but will also be an important step in translating the anti-MARCO Ab therapy from mice to humans as a new approach for cancer immunotherapy.
Citation Format: Vanessa F. Boura, Sofia Tyystjärvi, Ganna Oliynyk, Marie Arsenian-Henriksson, Mikael C.I. Karlsson, Silke Sohn. Targeting scavenger receptors for immunotherapy of cancer [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr B09.
Abstract B19: Robust antitumor effect of doxorubicin prodrug combined with anti-PD-1 in murine squamous cell cancer model
Authors: Lee Yoon Se , Kwon Minsu , Son In Kyung , Byun Youngro , Kim Sang Yoon 
Published: June 2021

Abstract
Background: Combination therapy of anti-PD-1 agents with other class of chemotherapeutic agents to improve treatment outcome is being attempted. Anthracycline-derived chemotherapeutic agents are known to activate immunogenic cell-death mechanism. Previously, we developed caspase-3 specific prodrug, MPD-1 containing doxorubicin. It is linked to peptide moiety cleavable by caspase-3 produced during apoptosis induced by radiation therapy (RT). We hypothesized that anti-PD-1 alone may activate MPD-1 by producing caspase-3 and reinforce antitumor efficacy of MPD-1 and anti-PD-1 effect. This study was designed to evaluate the antitumor effects of combined treatment of anti-PD-1 and MPD-1 in murine squamous cell carcinoma models.
Methods: Murine SCC VII (squamous cell carcinoma) cells were inoculated to flank of mice, female C3H/J. We divided 6 treatment groups; control, RT, anti-PD-1, anti-PD-1 with MPD-1, RT with MPD-1, and triple therapy (anti-PD-1 + RT + MPD-1) (n = 5/each group). After tumor grew up to 100-200 mm3, treatment was initiated. Tumor size and mice weight were measured. Expression of caspase-3 was evaluated in cell lines and tumor tissues after each treatment. Distribution of CD8+, CD4+, and FoxP3+ cells was analyzed.
Results: RT with MPD-1, anti-PD-1 with MPD-1, and triple treatment enhanced the synergistic antitumor activity compared to single treatment in SCC VII bearing mice. Anti-PD-1 with MPD-1 presented slightly better antitumor effect than RT with MPD-1. Caspase-3 was produced in tumor tissue of anti-PD-1 treatment group, which enhanced antitumor effect of activated MPD-1, while cell after anti-PD-1 did not enhance caspase-3 expression. Triple treatment suppressed tumor growth mostly, which was sustained more than 2 weeks even after cessation of treatment. Proportion of CD45+CD8+ T-cells in triple treatment group was increased mostly among tumor-infiltrating lymphocytes. Body weight of each treatment group was not significantly different.
Conclusion: Systemic anti-PD-1 initiates apoptosis and produces caspase-3. This process activates MPD-1 and induces sequential mediated by tumor-infiltrating lymphocytes. Combined anti-PD-1 and MPD-1 treatment will be effective for the distant metastatic lesions.
Citation Format: Yoon Se Lee, Minsu Kwon, In Kyung Son, Youngro Byun, Sang Yoon Kim. Robust antitumor effect of doxorubicin prodrug combined with anti-PD-1 in murine squamous cell cancer model [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr B19.
Abstract B30: Transient interferon suppression renders nerve sheath sarcomas susceptible to targeted viroimmunotherapy
Authors: Ghonime Mohammed G. , Cassady Kevin A. 
Published: June 2021

Abstract
Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive soft tissue sarcomas resistant to most cancer treatments. Surgical resection remains the primary treatment; however, this is often incomplete, ultimately resulting in high mortality and morbidity rates. There has been a resurgence of interest in oncolytic virotherapy because of encouraging preclinical and clinical trial results. Oncolytic Herpes simplex virus (oHSV) selectively replicates in cancer cells, lysing the cell and inducing antitumor immunity. We previously showed that basal interferon (IFN) signaling increases interferon stimulated gene (ISG) expression, restricting viral replication in almost 50% of MPNSTs. The FDA-approved drug ruxolitinib (RUX) temporarily resets this constitutively active STAT signaling and renders the sarcoma cells susceptible to oHSV infection in cell culture. In the studies described, we translated our in vitro results into a syngeneic MPNST tumor model. Consistent with our previous results, murine MPNSTs exhibit a similar IFN- and ISG-mediated resistance mechanism and virotherapy alone provides no antitumor benefit in vivo. However, when mice are pretreated with ruxolitinib, this reduces ISG expression, making the tumors susceptible to oHSV infection. Ruxolitinib pretreatment improves viral replication and alters the oHSV-induced immune-mediated response. Our results show that this combination therapy increases CD8 T-cell activation in the tumor microenvironment and that this population is indispensable for RUX+oHSV antitumor benefit. Of note, animals treated with the combination therapy have developed a systemic circulating memory response against the specific tumor antigen. These data suggest JAK inhibition prior to oncolytic virus treatment augments both oHSV replication and the immunotherapeutic efficacy of viroimmunotherapy.
Citation Format: Mohammed G. Ghonime, Kevin A. Cassady. Transient interferon suppression renders nerve sheath sarcomas susceptible to targeted viroimmunotherapy [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr B30.
Abstract B39: Regulation and function of IL-1b in immune modulation of pancreatic cancer
Authors: Das Shipra , Vogt Sandra , Hadju Christina , Bar-Sagi Dafna 
Published: June 2021

Abstract
Pancreatic intraepithelial neoplasms (PanINs) are well-defined precursor lesions of pancreatic ductal adenocarcinoma (PDA). The initiation and progression of PanINs is marked by dynamic stromal reconstruction and localized acute inflammation. Using an orthotopic transplantation model of early and advanced pancreatic neoplasia in immunocompetent recipient mice, we have uncovered a crucial role for the cytokine IL-1b in KRasG12D-driven PanIN evolution. Tumor cell-derived IL-1b¢ was found to be critical for shaping the protumorigenic PanIN microenvironment by promoting activation of quiescent pancreatic stellate cells and establishing an immunosuppressive milieu mediated by M2 macrophages, MDSCs and CD1dhiCD5+ regulatory B cells. Furthermore, loss of IL-1 signaling in tumor stroma activates the cytotoxic T-cell immune response, significantly attenuates PanIN growth and confers survival advantage to PDAC-bearing mice. Tumor cell expression of IL-1b in vivo is driven by upregulation of TLR4 signaling and activation of the NLRP3 inflammasome. KrasG12D enhances surface TLR4 expression, sensitizing transformed cells to TLR4 ligands in the microenvironment, including the pancreatic microbiome. Collectively, our study describes a complex tumor-stromal interplay orchestrated by the TLR4-NLRP3-IL-1b signaling axis, which is critical for shaping the tumor microenvironment and driving pancreatic tumorigenesis.
Citation Format: Shipra Das, Sandra Vogt, Christina Hadju, Dafna Bar-Sagi. Regulation and function of IL-1b in immune modulation of pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr B39.
Abstract B64: CD4 help is required for the generation of a transcriptionally distinct cytolytic CD8 T-cell subset to control chronic infection and tumor
Authors: Zander Ryan , Schauder David , Cui Weiguo 
Published: June 2021

Abstract
“CD4 help” is crucial to sustain the function of exhausted CD8 T cells, yet the detailed mechanisms by which CD4 help regulates CD8 T-cell differentiation and function during chronic viral infection remains elusive. Here, using single-cell RNA-sequencing (scRNA-seq) we show that CD8 T cells responding to chronic viral infection are more heterogeneous than previously appreciated, with three transcriptionally distinct subsets dominating the late phase of the antiviral response. Importantly, our findings uncover the formation of a previously unrecognized CD8 T-cell subset that exhibits potent cytolytic function. This subset is characterized by high expression of killer cell lectin-like receptors Klre1 and Klra9, the chemokine receptor CX3CR1, and the transcription factors T-bet and Zeb2. Notably, our data further demonstrate that the formation of this cytotoxic subset is critically dependent on CD4 help and that exploitation of this developmental pathway may be used therapeutically to enhance cytotoxic CD8 T-cell infiltration into the tumor. These findings uncover novel cellular and molecular mechanisms of how “CD4 help” regulates CD8 T-cell differentiation during persistent infection and have implications towards optimizing the generation of protective CD8 T cells in immunotherapy.
Citation Format: Ryan Zander, David Schauder, Weiguo Cui. CD4 help is required for the generation of a transcriptionally distinct cytolytic CD8 T-cell subset to control chronic infection and tumor [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr B64.
Abstract B80: Frequency of tumor-reactive T cells in the blood of breast cancer patients and healthy donors
Authors: Pinho Mariana P. , Patente Thiago A. , Flatow Elizabeth A. , Barbuto José Alexandre M. 
Published: June 2021

Abstract
As cancer immunotherapy gains importance, the determination of a patient’s ability to react to his/her tumor is unquestionable. Though the presence of T cells that recognize specific tumor antigens is well established, the total frequency of tumor-reactive T cells in humans is difficult to assess, especially due to the lack of broad analysis techniques. Here, we describe a strategy that allows this determination using T-cell proliferation induced by tumor cell-lysate pulsed dendritic cells as the readout. The frequency of tumor-specific T cells was determined, in healthy donors and cancer patients, by challenging multiple wells containing a defined number of T cells with autologous monocyte-derived dendritic cells loaded with tumor lysates and assessing the wells with T-cell proliferation by CFSE dilution. It was possible to find CD4+ and CD8+ T cells specific for the lysate of the breast cancer cell lines MCF-7 (luminal), SK-BR-3 (Her2 subtype) and MDA-MB-231 (triple-negative) in the blood of most healthy donors. All healthy donors tested had tumor cell lines-reactive T cells for at least one of the cell lines, some, not only in the naive, but also in the memory compartment. Patients had higher frequencies of reactive T cells and, unexpectedly, this was not correlated to the frequency of tumor-reactive infiltrating T cells. The method showed here seems to be a robust and powerful strategy to evaluate the T-cell response against cancer, that has already helped to unveil some important aspects about the breast tumor-reactive T cell repertoire in humans, and opens the possibility of tracking T-cell repertoire changes along disease progression. Financial support: FAPESP (2014/25988-1).
Citation Format: Mariana P. Pinho, Thiago A. Patente, Elizabeth A. Flatow, José Alexandre M. Barbuto. Frequency of tumor-reactive T cells in the blood of breast cancer patients and healthy donors [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr B80.