bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract A028: Defining immune pathways involved in the depletion of B-cell precursor acute lymphoblastic leukemia-initiating cells following early-life cytomegalovirus (CMV) infection in mice
Authors: Farrokhi Ali , Atre Tanmaya , Marquez1 Citlali , Gantt Soren , Reid Gregor 
Published: December 2023

Abstract
Background: B-cell acute lymphoblastic leukemia (B-ALL) is one of the most common forms of childhood cancers. Epidemiological studies have shown contrasting results regarding the role of infections in the risk of leukemia, and there is still no clear explanation for the pro- or anti-leukemia effects.
Aim: This study aimed to investigate the influence of cytomegalovirus (CMV) infection on the development of B-ALL and identify the underlying immune mechanisms involved.
Materials and Methods: In this study, Eμ-Ret transgenic mice were used as a model for hyperdiploid B-ALL, and luciferase-tagged CMV was used as a common early-life infection. The impact of infection on different subsets of B cells and leukemic initiating cells (LICs) in the bone marrow and spleen of neonatal and adult mice was assessed using multicolor flow cytometry. To gain insights into the mechanisms that impact LICs after infection, we sorted LICs from the splenocytes of infected and non-infected RFP mice seven days after infection, and total RNA sequencing (RNA-seq) was performed for gene expression analysis. We used neutralizing antibodies to evaluate the role of different cytokines/chemokines in mediating LIC depletion in vivo.
Results: Significant infection-induced depletion of preleukemic cells occurred in infected neonate Eμ-ret mice on BALBc, BALBc/FVB (F1) and BALBc/C57 (F1) backgrounds. This depletion showed an age-dependent pattern, with only infection in the first week after birth reducing the LICs numbers. Depletion of preleukemia was dependent on Stat4 and p40 homodimer/monomers, but not p40 heterodimers (IL-12 and IL-23). Several chemokines/cytokines, including IFNg and TNFa, showed high levels of expression in the serum of CMV-infected pups but not in adult mice. RNA sequencing indicated that IFNg and TNFa exerted a direct effect on preleukemic cells. In vivo neutralization of IFNg completely blocked the depletion effect of CMV infection. Further experiments confirmed that this cytokine works downstream of the Stat4 signaling pathway.
Conclusion: This is the first model to study the impact of CMV infection and the time of its exposure on B-ALL initiating cells. The identified Stat4-, IL12p40 homodimer/monomer-, and IFNg- driven activities could inform future treatment and prevention approaches for B-ALL.
Citation Format: Ali Farrokhi, Tanmaya Atre, Citlali Marquez1, Soren Gantt, Gregor Reid. Defining immune pathways involved in the depletion of B-cell precursor acute lymphoblastic leukemia-initiating cells following early-life cytomegalovirus (CMV) infection in mice [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A028.
Abstract A031: Discovery and characterization of a novel, immunoproteasome activator that modulates the immunopeptidome, increases MHC class I antigenic presentation and enhances antitumor immunity
Authors: Driscoll James J. , Rana Priyanka S. , Ignatz-Hoover James J. 
Published: December 2023

Abstract
The transformative success of cancer immunotherapy has revolutionized cancer treatment and can induce long lasting responses in patients with cancers from a wide range of histologies. However, only a fraction of patients respond to immunotherapy and cancer cells escape immunosurveillance by downregulating antigen presentation through mechanisms that remain elusive. Proteasomes play a central role in the immune response by generating peptides from intracellular antigens which are presented on the cell surface for recognition by CD8+ cytotoxic T lymphocytes (CTLs). Immune cells contain a highly specialized variant of proteasomes, known as immunoproteasomes, in which the three constitutive catalytic subunits are replaced by cytokine-inducible, homologous catalytic subunits. Immunoproteasomes are specially adapted for a role in MHC class I antigen processing and presentation to CD8+ T-cells. Here, we performed a high-through screen (HTS) to detect novel molecular entities that activated proteasomal peptide-hydrolyzing activity. We identified a curated panel of molecules which not only enhanced proteasomal hydrolysis of the cell-permeable substrate LLVY-R110 but also enhanced the presentation of MHC class I antigens. E.G7-Ova is a mouse lymphoma cell line derived by electroporation of EL4 cells (C57BL/6, H-2b, T lymphoma) with chicken ovalbumin (OVA) cDNA. Proteasomes degrade OVA to generate the peptide SIINFEKL that is presented by MHC-class I molecules. Studies demonstrated that the hits identified in the screen increased SIINFEKL presentation on E.G7-Ova cells. The lead compound identified in the HTS, compound A, dramatically enhanced expression of the proteasome activator PA28, which is expressed by PSME1 and PSME2. Treatment of multiple myeloma (MM) cells with compound A enhanced the hydrolysis of Ac-ANW-MCA, which is selectively cleaved by the immunoproteasome beta5-associated catalytic subunits. Treatment of MM cells with compound A followed by mass spectrometry (MS) indicated that the relative presentation of individual antigenic peptides bound to MHC class I molecules on tumor cells was dramatically increased. Novel immunoproteasome-selective therapeutics have the potential to generate neoantigens and upregulate cspecific antigens on tumor cells to enhance CD8+ T-cell-mediated control of human cancers.
Citation Format: James J. Driscoll, Priyanka S. Rana, James J. Ignatz-Hoover. Discovery and characterization of a novel, immunoproteasome activator that modulates the immunopeptidome, increases MHC class I antigenic presentation and enhances antitumor immunity [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A031.
Abstract A038: Targeting TCTP overcomes resistance to T cell-mediated immunotherapy by reversing the multi-malignant phenotypes of immune-refractory tumor cells
Authors: Kim Tae Woo 
Published: December 2023

Abstract
Cancer immunotherapy, particularly T cell-mediated therapy such as immune checkpoint blockade (ICB) and adoptive T cell transfer (ACT), has shifted the paradigm for cancer treatment. However, the emergence of immune-refractory tumor has limited its clinical success by disrupting one or more steps of the cancer immunity cycle. In addition, multi-malignant phenotypes of immune-refractory tumor cells are also one of the major causes result poor prognosis of patients. We need to identify novel predictive biomarker allowing for the selection of patients who will receive clinical benefit from immune-refractory tumors. Therefore, identifying the immune-resistance and multi-malignant factor, which not only can be targeted by clinically available medicines is very important. Here, we identified TCTP as a novel factor conferring multi-malignant phenotypes of immune-refractory tumor cells. We discovered a vital role of TCTP at the crossroads between multi-malignant tumor cells and the anti-cancer immunity system by demonstrating that TCTPhigh tumor cells enriched by immune selection pressure drive immune-refractory phenotypes. Importantly, the expression levels of TCTP within the tumors significantly associated with the clinical response of anti-PD-L1 therapy, which suggest TCTP as a prognostic marker in the case of clinical trials. Furthermore, targeting TCTP by clinical available drug overcomes the resistance to T cell-mediated therapy including ICB and ACT. Thus, our findings demonstrated that TCTP could be a both a valid target a prognostic marker providing a framework for patient selection to apply combined therapy of T cell-mediated therapy with TCTP-targeting drugs.
Citation Format: Tae Woo Kim. Targeting TCTP overcomes resistance to T cell-mediated immunotherapy by reversing the multi-malignant phenotypes of immune-refractory tumor cells [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A038.
Abstract A054: Anti-CTLA-4 generates memory T-cell with greater expansion and functionality than anti-PD-1
Authors: Mok Stephen , Liu Huey , Anang Nana-Ama A.S. , Mancuso James J , Çobanoğlu Didem Ağaç , Allison James P 
Published: December 2023

Abstract
Blocking either cytotoxic T-lymphocyte antigen-4 (CTLA-4) or programmed cell death-1 (PD-1) pathway results in distinct T-cell differentiation. We investigated the effects of anti-CTLA-4 and anti-PD-1 on memory T-cell formation in mice. Anti-CTLA-4 generates a more potent memory response than anti-PD-1. Memory T-cells generated by anti-CTLA-4 expand at a greater frequency, have greater cytokine production, and exhibit higher antitumor activity than those generated by anti-PD-1. These memory cells also more frequently differentiate into KLRG1+ effector CD8 T-cells during re-challenge. Additionally, anti-CTLA-4 generates more TCF-1+ memory-like T-cells, while anti-PD-1 results in more TOX+ terminally differentiated T-cells. Together, we provide insights into the long-term effects of these immunotherapies on the immune system.
Citation Format: Stephen Mok, Huey Liu, Nana-Ama A.S. Anang, James J Mancuso, Didem Ağaç Çobanoğlu, James P Allison. Anti-CTLA-4 generates memory T-cell with greater expansion and functionality than anti-PD-1 [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A054.
Abstract B002: Vidutolimod, an immunostimulatory virus-like particle, reduces proliferation but enhances the activation of tumor-specific T cells
Authors: Fischer Travis D. , Lemke-Miltner Caitlin , Weiner George J. 
Published: December 2023

Abstract
One approach to enhancing the anti-tumor T cell response is to alter the tumor microenvironment (TME) through intratumoral injection (IT) of immunostimulatory agents such as Vidutolimod (Vidu). Vidu is a virus-like particle (VLP) composed of a TLR9 agonist (CpG-A, known as G10) encapsulated by the Qβ bacteriophage capsid. IT Vidu shows considerable promise in early phase clinical trials. The immune response to Vidu is initiated by induction of IFNa production by pDCs within the TME. This effect is dependent on coating of Vidu with antibodies against the Qb capsid. This is followed by a series of changes in the TME that ultimately result in an enhanced anti-tumor T cell response. Mouse models have shown that the efficacy of IT Vidu depends on the presence of both CD4+ and CD8+ T cells. Most studies to date exploring the impact of Vidu on T cells have focused on the overall T cell population. The current studies were designed to further assess the complex mechanisms by which Vidu induces an anti-tumor T cell response through use of the well-established OT-1 mouse model that allows for analysis of the tumor-specific T cell population. OT-1 mice contain CD8+ T cells with a transgenic TCR that recognizes the ovalbumin (OVA) peptide SIINFEKL sequence (OVA257-264) presented on MHC Class I. Prior to culture, OT-1 splenocytes were labeled with CellTrace Violet in order to monitor proliferation over time. OT-1 splenocytes were then cultured with EL4 cells (an OVA-negative T lymphoblast cell line) or E.G7-OVA (OVA-expressing EL4 derivative cells). Minimal proliferation or evidence of T cell activation was seen when OT-1 CD8+ T cells were cultured with EL4 cells regardless of the addition of Vidu and anti-Qβ antibodies. OT-1 CD8+ T cells cultured with E.G7-OVA cells showed both proliferation and activation as indicated by increased intracellular IFNy and surface PD-1. Addition of Vidu and anti-Qb antibody reduced OT-1 CD8+ proliferation but enhanced production of IFNγ and expression of PD-1. The increase in IFNγ and PD-1 expression was strongest in the dividing OT-1 CD8+ T cell population. Preliminary results of ongoing in vivo studies are consistent with these results. In summary, Vidu reduces proliferation but enhances phenotypic markers of activation expressed by tumor-specific CD8+ T cells (OT-1 cells) when co-cultured with cells expressing OVA, their target antigen. Markers of activation are most notable in dividing OT-1 CD8+ T cells.
Citation Format: Travis D. Fischer, Caitlin Lemke-Miltner, George J. Weiner. Vidutolimod, an immunostimulatory virus-like particle, reduces proliferation but enhances the activation of tumor-specific T cells [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr B002.
Abstract B021: In vivo gain-of-function screen identifies CREB5, a novel ECM modulator that promotes immunotherapy resistance via the Collagen-Lair1 axis
Authors: Tiwari Payal , Colvin Kayla , Kim Sarah , Kammula Ashwin , Anderson Seth , Revach Or-Yam , Vyas Maulik , Talamas Jessica A , Demehri Shadmehr , Yates Kathleen , Doench John , Hahn William C , Manguso Robert 
Published: December 2023

Abstract
Treatment with immune checkpoint inhibitors induce remarkable clinical responses in several cancer types. However, most cancer patients do not respond to immunotherapy, and patients who initially respond often exhibit acquired resistance. Understanding the universe of immune evasion strategies will enable the design of more effective immunotherapies. Here, we identified genes that drive immune evasion by performing a genome scale in vivo CRISPR gain-of-function screen in tumors treated with anti-PD-1 antibodies; and discovered the transcription factor CREB5 as a top resistance mediator. Using transcriptional profiling, we showed CREB5 drives upregulation of extracellular matrix genes including collagen and collagen-stabilizing factors. We found CREB5 or collagen (Col1a1, Col4a1, or Col16a1) overexpressing tumors exhibit poor responses to anti-PD-1. Collagen is the major ligand for the inhibitory receptor LAIR1, which is broadly expressed on T cells, B cells, NK cells, and myeloid cells. Deletion of LAIR1 in mice or overexpression of the decoy receptor LAIR2 in tumors abrogates the resistance-causing effect of CREB5 or collagen overexpression, suggesting that CREB5 overexpression drives resistance partly via collagen-LAIR1 inhibitory signaling. In summary, we have identified a gene that can induce fibroblast-like features in tumor cells to promote immunotherapy resistance. Further investigation of pathways that induces stromal mimicry in cancer cells could identify novel immunotherapy targets.
Citation Format: Payal Tiwari, Kayla Colvin, Sarah Kim, Ashwin Kammula, Seth Anderson, Or-Yam Revach, Maulik Vyas, Jessica A Talamas, Shadmehr Demehri, Kathleen Yates, John Doench, William C Hahn, Robert Manguso. In vivo gain-of-function screen identifies CREB5, a novel ECM modulator that promotes immunotherapy resistance via the Collagen-Lair1 axis [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr B021.
Abstract B037: Single-cell analysis reveals immune characteristics linked to poor prognosis in Fusobacterium nucleatum-infected colorectal cancer
Authors: Choi Ilseok , Kim Kyung-A , Han Yoon Dae , Kim Sang Cheol , Kim Han Sang , Lee Insuk 
Published: December 2023

Abstract
Fusobacterium nucleatum (Fn) is commonly detected in colorectal cancer (CRC) and worsens patient survival. Fn appears to play a role in colorectal cancer carcinogenesis through suppression of the antitumor immune response. Aiming to uncover the underlying mechanisms, we collected 42 samples of surgically removed colon tissues from patients newly diagnosed with colon cancer. To analyze the bacterial community composition within these tissues, we utilized amplicon sequencing, targeting the V4 variable region of the 16S rRNA. We performed single-cell RNA sequencing (scRNA-seq) analysis of tumor-infiltrating immune cells from Fn-infected [Fn (+)] and Fn-uninfected [Fn (−)] patients. By utilizing gene expression signature derived from scRNA-seq data and bulk transcriptome profiles of the TCGA cohort, we identified immune cell types associated with Fn infection in CRC. Using RNA velocity and cell-cell interaction analysis of single-cell transcriptome data, we unraveled immune cell subtypes modulated by Fn infection. Furthermore, trajectory-based differential expression analysis and single-cell gene network analysis shed light on how the intratumor immune system is disturbed by Fn infection. A novel gene signature had a poor prognostic impact in patients with Fn-infected tumors, compared with Fn-uninfected patients in the TCGA cohort. Overall, this study identified a novel potential Fn-related immune evasion mechanism, beyond suppression of T cell-mediated immune response. Novel gene signatures with a poor prognostic impact can be used for patient stratification and developing targeted strategies in patients with Fn infection.
Citation Format: Ilseok Choi, Kyung-A Kim, Yoon Dae Han, Sang Cheol Kim, Han Sang Kim, Insuk Lee. Single-cell analysis reveals immune characteristics linked to poor prognosis in Fusobacterium nucleatum-infected colorectal cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr B037.
Abstract B045: EV-mediated immune modulation of CD8+ T cells in renal cell carcinoma
Authors: Jaschkowitz Greta , Noessner Elfriede , Zaccagnino Angela , Stöckle Michael , Junker Kerstin , Zeuschner Philip 
Published: December 2023

Abstract
Introduction: Treatment regimens for advanced renal cell carcinoma (RCC) involve immune checkpoint inhibition targeting the PD-(L)1 pathway. PD-L1 is often overexpressed on tumor cells in advanced disease and plays a crucial role in regulating tumor-directed immune responses. It can also be expressed on tumor-secreted extracellular vesicles (EVs), which are an essential part of intercellular communication. PD-L1 carrying EVs have been shown to have immunomodulatory effects in several tumor entities, however their role in RCC is still unknown. The aim of this study was the evaluation of putative immunomodulatory effects of RCC-derived small EVs on CD8+ T cells.
Materials and Methods: EVs of 5 untreated as well as interferon γ (IFNγ)-treated RCC cell lines were isolated through serial ultracentrifugation. Quality and quantity of the EVs were verified using Western Blotting (WB), Nano Particle Tracking Analysis and Transmission Electron microscopy, their PD-L1 expression was analyzed semi quantitatively through WB. CD8+ T cells were isolated from the blood of healthy donors, activated and subsequently co-cultured with RCC-derived EVs for a duration of 3 days. Proliferation and PD-1 expression of the T cells was assessed using flow cytometry. ELISAs were performed to analyze cyto- and chemokine secretion.
Results: All RCC cell lines expressed PD-L1, albeit at varying low levels. Four out of 5 treated cell lines responded to IFNγ treatment with an upregulation of PD-L1 expression on both cells and secreted EVs. Co-cultures of CD8+ T cells and RCC-derived EVs, particularly PD-L1+ EVs isolated from IFNγ-stimulated cells, lead to a reduction in T cell PD-1 expression. Additionally, PD-L1-expressing EVs of RCC cell line RCC53 had an antiproliferative effect on CD8+ T cells. EVs also increased the secretion of IL-2, IL-10, CXCL10 and CCL5 by the CD8+ T cells.
Conclusions: PD-L1 is expressed at low levels in RCC cell lines. However, repetitive IFNγ stimulation can lead to upregulation of PD-L1 on both cells and EVs enabling us to use this model to further investigate EV-mediated, PD-L1 dependent effects. In co-cultures, RCC-derived EVs impede early T cell activation and proliferation patterns of CD8+ T cells. Furthermore, early results indicate a shift towards a more pro-inflammatory cyto- and chemokine production by the T cells induced by RCC-derived EVs. The results support the hypothesis of a tumor-EV-mediated immune modulation in RCC.
Citation Format: Greta Jaschkowitz, Elfriede Noessner, Angela Zaccagnino, Michael Stöckle, Kerstin Junker, Philip Zeuschner. EV-mediated immune modulation of CD8+ T cells in renal cell carcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr B045.
Abstract B049: Lipid nanoparticle-delivered toll-like receptor agonists are highly effective in cancer immunotherapy
Authors: Bai Jun , Su Fei , Li Chen , Wu Yujing , Li Jing , Zhao Xiaobin , Yang Yongsheng , Lee Robert J 
Published: December 2023

Abstract
Background: Tumor immunotherapy has shown promising efficacy in various types of cancer. However, the effectiveness of immunotherapy is often limited by the immune-suppressive microenvironment within tumors. To address this challenge, we developed a method of intratumoral injection using lipid nanoparticles (LNPs) to deliver Toll-like receptor 7, 8, and 9 agonists. LNPs effectively enhance immune activation while reducing systemic responses by increasing drug retention within the tumor.
Methods: We encapsulated 30nt-CpG and Resiquimod into LNPs (QTsomeTM). Subcutaneous inoculation of 2 × 106 MC38 cells was performed in mice. Once the average tumor volume reached approximately 100mm3, we divided 15 mice into 3 groups based on tumor volume. Intratumoral injections began on the same day of grouping, with a dosage of 1mg/kg (5 injections every 3 days). Tumor volume and body weight were measured twice a week. We conducted two parallel experiments, each with 7 mice for the MC38 model and 8 mice for the B16 melanoma model in each group, to compare the efficacy of 26nt-CpG and 30nt-CpG.
Results: On the 15th day post-dosing, the tumor growth inhibition rate (TGI) was 79.9% (P&lt;0.001), resulting in a 73.7% increase in survival rate. LNP-delivered 26nt-CpG demonstrated a TGI rate of 75.4% (P&lt;0.001), while 30nt-CpG showed a TGI of 81.9% (P&lt;0.001). Interestingly, the 26nt-CpG group exhibited faster weight gain, indicating better safety. In the mouse B16 melanoma model, LNP-delivered 26nt-CpG achieved a TGI rate of 75.2% (P&lt;0.001), slightly higher than 30nt-CpG (71.0%, P&lt;0.001), and also resulted in faster weight gain.
Conclusion: In conclusion, the use of LNP-delivered Toll-like receptor agonists demonstrated excellent tumor therapeutic effects and good safety in mouse models. Activation of Toll-like receptors effectively stimulated immune cells such as CD8+ T cells and NK cells, enhancing their ability to kill tumor cells. Direct injection of LNPs into the tumor improved this effect while reducing systemic side effects. This drug holds promise as a broad-spectrum anti-tumor treatment and may have potential for expanding the indications of existing tumor immunotherapies.
Citation Format: Jun Bai, Fei Su, Chen Li, Yujing Wu, Jing Li, Xiaobin Zhao, Yongsheng Yang, Robert J Lee. Lipid nanoparticle-delivered toll-like receptor agonists are highly effective in cancer immunotherapy [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr B049.