bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract PO032: TIM3 regulation by phosphatidylserine
Authors: Smith Courtney M. , Li Alice , Krishnamurthy Nithya , Lemmon Mark A. 
Published: February 2021

Abstract
Immune responses have been successfully reactivated in cancer by targeting inhibitory receptors such as PD-1 on exhausted T cells to block immune checkpoints. Many patients do not respond, however, and a key challenge in immuno-oncology is to identify and understand new immune-regulatory targets to increase response rates. One other co-inhibitory receptor in T cells is TIM3, which – like PD-1 – is upregulated on exhausted T cells in the tumor microenvironment. TIM3 belongs to a family of phosphatidylserine (PS) receptors with well-documented roles in efferocytosis by phagocytes. However, the role of PS in regulating TIM3 remains unclear. Previous studies have shown that TIM3 can variously enhance or inhibit T cell signaling, though exactly how TIM3 accomplishes this range of activity is unknown. We therefore investigated how TIM3 levels modulate T cell signaling, and how PS in turn influences TIM3 activity. We found that TIM3 promoted T cell activity in a Jurkat T cell model when expressed at high – but not low – levels on the cell surface. We also confirmed the ability of human TIM3 to bind PS with low micromolar affinity using surface plasmon resonance. To investigate how PS affects the ability of TIM3 to promote T cell signaling in this model, we employed several approaches, including adding PS to the cell culture, manipulating TIM3 to reduce or abrogate PS binding (using chimeric receptors and TIM3 mutants), and pharmacological blockade of PS binding using a functional TIM3 antibody. Together, these studies supported a role for PS in regulating TIM3 activity, where decreased or abrogated PS binding prevented TIM3 from promoting T cell signaling. We also sought to understand what changes in T cell receptor (TCR) signaling might account for the TIM3-dependent effects we observed. We found that TIM3 did not impact phosphorylation of downstream components in the TCR signaling cascade. Rather, cells expressing high – but not low – surface levels of TIM3 displayed enhanced phosphorylation of receptor components in the TCR signaling pathway, similar to what has been reported for PD-1. We hypothesize that TIM3 modulates TCR signaling by modifying the localization and/or dwell time of one or more signaling effector proteins (e.g. phosphatases) in a manner dependent on PS engagement. The consequences of this are then determined by surface levels of TIM3. Our results demonstrate that PS does function as a ligand capable of modulating TIM3 activity, and provide new mechanistic insight into how TIM3 modulates TCR signaling.
Citation Format: Courtney M. Smith, Alice Li, Nithya Krishnamurthy, Mark A. Lemmon. TIM3 regulation by phosphatidylserine [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO032.
Abstract PO034: Mechanisms and microbial Influences on CTLA-4 and PD-1-based immunotherapy in the treatment of cancer: A narrative review
Authors: Miller Peter L. , Carson Tiffany L. 
Published: February 2021

Abstract
Background: The relationship between gastrointestinal (GI) bacteria and the response to anti-CTLA-4 and anti-PD-1 immunotherapy in the treatment of cancer can potentially be enhanced to allow patients to maximally respond to these treatments. Insight into the complex interaction between gut microbiota and the human adaptive immune system will help guide future immunotherapeutic cancer treatments to allow a more robust clinical response and fewer adverse effects in patients requiring these drugs. This review highlights these interactions as well as the potential for the creation of “oncomicrobiotics” that would selectively tailor one’s GI bacteria to maximally respond to anti-CTLA-4 and anti-PD-1 treatments.
Main Body: CTLA-4 is an antigen on the surface of T cells which, upon stimulation, leads to inhibition of activated T cells to terminate the immune response. However, many types of tumor cells can upregulate CTLA-4 in the tumor microenvironment, allowing these cells to evade targeting and destruction by the body’s immune system by prematurely inhibiting T cells. Increased representation of Bacteriodes fragilis and Burkholderia cepacia in the GI tract of patients receiving CTLA-4-based immunotherapy led to a stronger therapeutic effect while minimizing adverse side effects such as colitis. In addition, introducing bacteria involved in vitamin B and polyamine transport to the GI tracts of patients treated with anti-CTLA-4 drugs led to increased resistance to colitis while maintaining therapeutic efficacy. PD-1 is another molecule upregulated in many tumor microenvironments which acts in a similar manner to CTLA-4 to tone down the anti-neoplastic actions of T cells. Antibodies to PD-1 have shown promise to help allow the body’s natural immune response to appropriately target and destroy tumor cells. The presence of Bifidobacterium, namely Bifidobacterium breve and longum, in the GI tracts of cancer patients has the potential to create a more robust immune response to anti-PD-1 drugs while limiting medication-induced adverse effects. The development of “oncomicrobiotics” has the potential to help tailor one’s gut microbiota to allow patients to maximally respond to immunotherapy without sacrificing increases in toxicity. These oncomicrobiotics may possibly include antibiotics, probiotics, postbiotics and/or prebiotics. However, many challenges lie ahead in the creation of oncomicrobiotics.
Conclusion: The creation of oncomicrobiotics may allow many patients receiving anti-CTLA-4 and PD-1 immunotherapy to experience prolonged survival and a better quality of life.
Citation Format: Peter L. Miller, Tiffany L. Carson. Mechanisms and microbial Influences on CTLA-4 and PD-1-based immunotherapy in the treatment of cancer: A narrative review [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO034.
Abstract PO040: High-throughput vascularized tumor array for In-vitro natural killer cell cytotoxicity testing
Authors: Song Jiyoung , Choi Hyeri , Park Dohyun , Yu James , Jeon Nooli 
Published: February 2021

Abstract
Colorectal cancer is second leading cause of cancer death. There have been many approaches proposed, such as anti-cancer drugs, chemotherapy and radiotherapy, however, there are still lack of breakthrough therapy designation. Cancer immunotherapies hold great promise, where the mechanism of interaction between immune cell and tumor remains poorly understood. Understanding of immune cell infiltration in solid tumor plays an important role in cancer immunotherapy. This paper describes injection molded plastic chip to mimic complex three-dimensional tumor-vasculature for evaluating immune cell infiltration and their cytotoxicity. Our device facilities simple and high-throughput screening, constituting of 28 wells per device. Using our system, Co-culture conditions that both tumors and blood vessels were adequately benefited were established. Also, we characterized the aberrant vasculature according to the colorectal tumor subtypes and confirmed increased blood vessel the permeability, which is the major feature of aberrant tumor vasculature. Moreover, we evaluated Natural killer(NK) cell infiltration and cytotoxicity according CMS subtypes. NK cell showed higher cytotoxicity to CMS 1 type colorectal cancer compared to the other subtypes. This result confirmed that NK cell is the crucial effector in innate immune system as a first line of defense against pathogens. Therefore, we propose our plastic microfluidic chip as a high-throughput screening platform to evaluate lymphocyte cytotoxicity to various solid tumor including immune infiltration.
Citation Format: Jiyoung Song, Hyeri Choi, Dohyun Park, James Yu, Nooli Jeon. High-throughput vascularized tumor array for In-vitro natural killer cell cytotoxicity testing [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO040.
Abstract PO056: The kinetics of the anti-glioblastoma immune response in immunocompetent mouse models is influenced by neglected factors
Authors: Noffsinger Breanna R. , Witter Alexandra , Shebani Natasha , Xiao Aizhen , Zhong Qing , Harris Tajie , Purow Benjamin 
Published: February 2021

Abstract
Due to the recent rise in immunotherapy research to treat Glioblastoma, immunocompetent mouse models have become increasingly crucial for the study of novel immunotherapies against brain tumors. However, the kinetics of the immune response against the most prevalent immunocompetent GBM models, GL261 and CT2A, have not been well studied, nor have they been compared adequately in the literature. In this study, we compared the immune response in these models using flow cytometry and immunohistochemistry. We investigated several factors that influence the immune response, such as kinetics, tumor size, and transfection status. We hypothesize that these factors influence the immune response enough to warrant consideration while studying new immunotherapeutic approaches for treating GBM. Our results will aid in the preclinical studies of immunotherapy for GBM by allowing scientists to make informed decisions about their chosen models.
Citation Format: Breanna R. Noffsinger, Alexandra Witter, Natasha Shebani, Aizhen Xiao, Qing Zhong, Tajie Harris, Benjamin Purow. The kinetics of the anti-glioblastoma immune response in immunocompetent mouse models is influenced by neglected factors [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO056.
Abstract PO062: Isolation of tumor-infiltrating lymphocytes for higher sensitivity gene expression profiling
Authors: Webb Lindsay M. , Naughton Bartholomew , Yalavarthi Sireesha , Bourin Clotilde , Moisan Jacques , Xu Chunxiao 
Published: February 2021

Abstract
Gene expression profiling is a powerful approach to address the mechanism of action (MOA) of cancer immunotherapy-driven reprogramming of tumor-infiltrating lymphocytes (TILs) in the tumor microenvironment. However, TILs, particularly T and NK cells, are a very rare population within the tumor. Gene expression profiling using Nanostring or RNAseq is often not sensitive enough to detect expression changes in rare populations, and it is difficult to separate gene expression profiles between different cell subsets. Although single-cell RNAseq can distinguish gene expression profiles between different cell subsets, it is very costly and would require many cells to be sequenced before obtaining the rare cell type of interest. Classically, fluorescence-activated cell sorting (FACS) has been used to isolate rare populations, but this method is a long process that can affect cell phenotype and results in dramatic cell loss. Thus, we developed a protocol for rapid and reproducible magnetic bead-based isolation of tumor-infiltrating lymphocytes (TILs) for higher sensitivity MOA studies. CD8 and CD4 TILs were isolated from both MC38 and CT26.KSA tumor models with high purity and sufficient yield for further Nanostring gene expression analysis. As expected, CD8 and CD4 T cell gene expression profiles were dramatically enriched in the isolated TILs compared to the whole tumor. Thus, our protocol for isolating TILs from mouse tumors can be applied broadly to multiple tumor types and provides sufficient yield to perform downstream high-sensitivity gene expression profiling.
Citation Format: Lindsay M. Webb, Bartholomew Naughton, Sireesha Yalavarthi, Clotilde Bourin, Jacques Moisan, Chunxiao Xu. Isolation of tumor-infiltrating lymphocytes for higher sensitivity gene expression profiling [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO062.
Abstract PO077: BT7480, a novel fully synthetic tumor-targeted immune cell agonist (TICA™) induces tumor localized 4-1BB agonism
Authors: Repash Elizabeth M. , Upadhyaya Punit , Lahdenranta Johanna , Kublin Jessica , Ma Jun , Kleyman Marianna , Chen Liuhong , Haines Eric , Battula Sailaja , McDonnell Kevin , Hurov Kristen , Brandish Philip , Keen Nicholas 
Published: February 2021

Abstract
Harnessing costimulatory molecules expressed on T and NK cells namely 4-1BB (CD137/TNFRSF9) is ideal for cancer immunotherapy. Despite promise preclinically, 4-1BB agonistic antibodies, were unable to demarcate hepatoxicity from efficacy in the clinic. Bispecific approaches promote target-mediated clustering of 4-1BB while limiting systemic and liver toxicity. Bicycles® are novel, fully synthetic, constrained bicyclic peptides with high affinity and selectivity to their targets. Their small size (~2kDa) and tunable pharmacokinetic parameters allow Bicycles to have superior tumor penetration and de-risk hepatoxicity concerns due to a renal clearance mechanism. We hypothesized that clustering and activation of 4-1BB could be attained by conjugating a 4-1BB binding Bicycle to a tumor antigen targeting Bicycle promoting a potent tumor-localized immune response. BT7480 is a tumor-targeted immune cell agonist (TICA™) targeting Nectin-4 and agonizing 4-1BB. Nectin-4 (PVRL4) is highly expressed in numerous tumor indications with unmet clinical needs. In an engineered 4-1BB reporter system, we found BT7480 induced potent 4-1BB agonism correlating to target antigen surface expression on the co-cultured tumor cells. Moreover, BT7480 induces cytokine secretion, including interleukin-2 and interferon gamma, in immune cell co-culture in the presence of tumor antigen. This activity is strictly dependent on Nectin-4 expression on tumor cells and the ability of the TICA to bind to both Nectin-4 and 4-1BB. In a MC38 (Nectin-4-expressing) syngeneic mouse model, intermittent dosing of BT7480 led to robust anti-tumor efficacy (22 out of 24 complete responders (CRs)). Importantly, a memory response was established in CR mice as resistance to a re-challenge with MC38 tumors was observed. Additionally, BT7480 led to increased intratumoral T cell infiltration without elevation of liver enzymes in a CT26 (Nectin-4-expressing) syngeneic mouse model. In non-human primates (NHPs), BT7480 exhibits dose linear exposure and is well tolerated up to 10mpk. BT7480 represents a new generation of chemically synthetic tumor antigen targeted 4-1BB agonists with potent efficacy and a favorable safety profile.
Citation Format: Elizabeth M. Repash, Punit Upadhyaya, Johanna Lahdenranta, Jessica Kublin, Jun Ma, Marianna Kleyman, Liuhong Chen, Eric Haines, Sailaja Battula, Kevin McDonnell, Kristen Hurov, Philip Brandish, Nicholas Keen. BT7480, a novel fully synthetic tumor-targeted immune cell agonist (TICA™) induces tumor localized 4-1BB agonism [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO077.
Abstract PO081: Systematic Generation of Allogeneic Immune-targeting Modalities for Glioblastoma
Authors: Salim Sabra K. , Wei Jiarun , Dimitrov Vassil , Chen Katherine , Venugopal Chitra , Vora Parvez , Moffat Jason , Singh Sheila K. 
Published: February 2021

Abstract
Glioblastoma (GBM) is one of the most common brain tumors in adults. Despite a standard-of-care including surgery and chemoradiotherapy, patients only live to a median of 15 months. This may be due to extensive spatiotemporal, intratumoral heterogeneity observed. This is thought to be created by a small population of stem-like cells marked by expression of CD133. CD133 has been shown to correlate with poor patient prognosis, metastases, relapse and worse overall survival in GBM. We thus created an anti-CD133 CAR-T therapy. Our CD133-targeting CAR-T (CART133) has shown great efficacy and in our patient-derived models of GBM. It has also exhibited safety in sparing healthy CD133-expressing cells, particularly, hematopoietic stem and progenitor cells, in our humanized model of hematopoiesis. However, in looking to the clinic, the generation of autologous CAR-Ts may be difficult as it requires sufficient numbers of a patient's own T-cells who may be immunocompromised after first-line therapy. Thus, we propose to generate allogeneic CAR-Ts that target CD133 (AlloCART133) from healthy donor T- cells. AlloCAR-T cells are genetically-edited to abrogate the T-cell receptor (TCR) to avoid graft-versus- host disease, a phenomenon in which immune-mismatch causes donor tissues to attack recipient tissues. These cells can thus be safe for a recipient while also maintaining their anti-tumor activity. AlloCART133 thus presents a clinically-relevant, off-the-shelf therapy for patients with GBM.
Citation Format: Sabra K. Salim, Jiarun Wei, Vassil Dimitrov, Katherine Chen, Chitra Venugopal, Parvez Vora, Jason Moffat, Sheila K. Singh. Systematic Generation of Allogeneic Immune-targeting Modalities for Glioblastoma [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO081.
Abstract PR002: Highly parallel knock-in targeting for genome engineering of cellular therapies
Authors: Roth Theodore L. , Marson Alexander 
Published: February 2021

Abstract
Genetically-engineered immune cell therapies have proven effective to treat some types of cancer, but most tumors still cannot be cured. Forward genetics with CRISPR loss-of-function screens in T cells have identified some mutations to enhance cellular therapies, however these methods do not yet take full advantage of the power of gain-of-function knock-in targeting to engineer cell functions. We developed a robust new platform to assess the functional effects of pools of knock-in constructs in parallel. We used high-efficiency nonviral gene editing to introduce large panels of candidate therapeutic knock-in constructs into a defined genome position in human T cells allowing us to compete the cells against each other and test which constructs enhance T cell function. High-throughput pooled screening of targeted cells identified distinct library members that promoted T cell fitness under various resting, stimulated and immunosuppressive in vitro conditions. Direct competition among adoptively transferred human T cells in immunodeficient mice revealed a subset of constructs that promoted in vivo accumulation of tumor infiltrating lymphocytes. Pooled knock-ins combined with single-cell sequencing also revealed high-dimensional cellular phenotypes induced by each construct ex vivo and in an in vivo tumor microenvironment. Overall, these studies demonstrate the power of pooled knock-in technology to discover and functionally characterize complex synthetic gene programs that can be written into targeted genome sites to generate more effective cellular therapies.
This abstract is also being presented as PO073.
Citation Format: Theodore L. Roth, Alexander Marson. Highly parallel knock-in targeting for genome engineering of cellular therapies [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PR002.
Abstract PR006: 27-Hydroxycholesterol acts on myeloid immune cells to induce T cell dysfunction, promoting breast cancer progression
Authors: Ma Liqian , Wang Lawrence , Nelson Adam T. , Han Chaeyeon , He Sisi , Henn Madeline A. , Menon Karan , Chen Joy J. , Baek Amy E. , Vardanyan Anna , Shahoei Sayyed Hamed , Park Sunghee , Shapiro David J. , Nanjappa Som G. , Nelson Erik R. 
Published: February 2021

Abstract
Breast cancer remains one of the leading causes of cancer mortality in the US. Elevated cholesterol is a major risk factor for breast cancer onset and recurrence, while cholesterol-lowering drugs, such as statins, are associated with a good prognosis. Previous work in murine models showed that cholesterol increases breast cancer metastasis, and the pro-metastatic effects of cholesterol were due to its primary metabolite, 27HC. In our prior work, myeloid cells were found to be required for the pro-metastatic effects of 27HC, but their precise contribution remains unclear. Here we report that 27HC impairs T cell expansion and cytotoxic function through its actions on myeloid cells, including macrophages, in an LXR-dependent manner. Many oxysterols and LXR ligands had similar effects on T cell expansion. Moreover, their ability to induce the LXR target gene ABCA1 was associated with their effectiveness in impairing T cell expansion. Interestingly, the enzyme responsible for the synthesis of 27HC, CYP27A1, is highly expressed in myeloid cells, suggesting that 27HC may have important autocrine or paracrine functions in these cells, a hypothesis supported by our finding that breast cancer metastasis was reduced in mice with a myeloid specific knockout of CYP27A1. Pharmacologic inhibition of CYP27A1 reduced metastatic growth and improved the efficacy of checkpoint inhibitor, anti-PD-L1. RNA sequencing of 27HC-treated macrophages and GSEA analysis provide further mechanistic insight, revealing an enrichment of MYC and NOTCH signaling pathways, both of which are documented pathways involved in tumor-associated macrophages. Taken together, our work suggests that targeting the CYP27A1 axis in myeloid cells may present therapeutic benefits and improve the response rate to immune therapies in breast cancer. Delineating the link between LXR and the known mechanisms of tumor-associated macrophages is important to fully understand 27HC-driven cancer metastasis. This work was supported by grants to ERN from the National Cancer Institute of the National Institutes of Health (R01CA234025) and METAvivor.
This abstract is also being presented as PO050.
Citation Format: Liqian Ma, Lawrence Wang, Adam T. Nelson, Chaeyeon Han, Sisi He, Madeline A. Henn, Karan Menon, Joy J. Chen, Amy E. Baek, Anna Vardanyan, Sayyed Hamed Shahoei, Sunghee Park, David J. Shapiro, Som G. Nanjappa, Erik R. Nelson. 27-Hydroxycholesterol acts on myeloid immune cells to induce T cell dysfunction, promoting breast cancer progression [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PR006.