bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract A042: Common gamma-chain signaling in NK cells promotes their Flt3L-dependent support of cDC1s in melanoma
Authors: Avanessian Shayan C , van den Bijgaart Renske J.E. , Chew Nayvin W , Tang Thao T , Barry Kevin C 
Published: October 2024

Abstract
Natural killer (NK) cells are an innate lymphocyte population that have an inherent ability to recognize and eliminate malignant cells without requiring prior sensitization. However, NK cells are more than just a population of killers—they are prominent producers of cytokines and chemokines, lending them a pivotal ability to orchestrate robust immune responses involving other immune cell types. We have previously shown that NK cells in the tumor microenvironment (TME) are critical regulators of type one conventional dendritic cells (cDC1s), which are required for protective immune responses against cancer and for the success of checkpoint blockade immunotherapies. Through the production of the cDC1-formative cytokine FMS-like tyrosine kinase 3 ligand (Flt3l/Flt3L in mice or FLT3LG/FLT3LG in humans), NK cells support cDC1 abundance in the melanoma TME. Indeed, the abundance of this innate immune axis of NK cells-FLT3LG-cDC1s defines checkpoint blockade-responsiveness in melanoma patients. Despite this clear clinical relevance, the molecular and cellular mechanisms underlying NK cell regulation of FLT3LG are not understood. Here, we investigated signals that modulate NK cell activity and found that the common gamma- chain cytokines IL-2 and IL-15 are uniquely able to upregulate Flt3L production by NK cells, and that treatment of NK cells with IL-2 and IL-15 led to increased support of cDC1s both in-vitro and in-vivo. This local NK cell support of cDC1s in the TME, in combination with checkpoint blockade, potentiates tumor control in the non-responsive B16F10 melanoma model. Furthermore, we demonstrated that a particular subset of immunomodulatory NK cells that excels in cytokine production is primarily responsible for the production of Flt3L in response to common gamma-chain signaling. By analyzing human melanoma patient datasets, we found that the abundance of immunomodulatory NK cells within the TME correlates both with FLT3LG and cDC1 abundance. These findings define the features of the TME and of NK cells that promote successful cancer responses and will inform future NK cell-based therapy approaches.
Citation Format: Shayan C Avanessian, Renske J.E. van den Bijgaart, Nayvin W Chew, Thao T Tang, Kevin C Barry. Common gamma-chain signaling in NK cells promotes their Flt3L-dependent support of cDC1s in melanoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr A042.
Abstract A055: CD47 predominates over CD24 as a macrophage immune checkpoint in cancer
Authors: Meglan Anna , Allen Juliet , Vaccaro Kyle , Velarde José , Chen Victor , Ribeiro Juliano , Blandin Jasmine , Mishra Ranjan , Ho Raymond , Love Jennifer , Reinhardt Ferenc , Bell George W , Chen Jin , Weinberg Robert , Yang Dian , Weissman Jonathan , Weiskopf Kipp 
Published: October 2024

Abstract
Macrophages hold tremendous promise as effectors of cancer immunotherapy, but the best strategies to provoke these cells to attack tumors remain unknown. Here, we evaluated the therapeutic potential of targeting two distinct macrophage immune checkpoints: CD47 and CD24. We found that antibodies targeting these antigens could elicit maximal levels of phagocytosis when combined together in vitro. However, to our surprise, via unbiased genome-wide CRISPR screens, we found that CD24 primarily acts as a target of opsonization rather than an immune checkpoint. In a series of in vitro and in vivo genetic validation studies, we found that CD24 was neither necessary nor sufficient to protect cancer cells from macrophage phagocytosis in most mouse and human tumor models. Instead, anti-CD24 antibodies exhibit robust Fc-dependent activity, and as a consequence, they cause significant on-target hematologic toxicity that was life-threatening in syngeneic mice. To overcome these challenges and leverage our findings for therapeutic purposes, we engineered a collection of 77 novel bispecific antibodies that bind to a tumor antigen with one arm and engage macrophages with the second arm. We discovered multiple novel bispecifics that maximally activate macrophage-mediated cytotoxicity and reduce binding to healthy blood cells, including bispecifics targeting macrophage immune checkpoint molecules in combination with EGFR, TROP2, and CD71. Overall, our findings indicate that CD47 predominates over CD24 as a macrophage immune checkpoint in cancer, and that the novel bispecifics we created may be optimal immunotherapies to direct myeloid cells to eradicate solid tumors.
Citation Format: Anna Meglan, Juliet Allen, Kyle Vaccaro, José Velarde, Victor Chen, Juliano Ribeiro, Jasmine Blandin, Ranjan Mishra, Raymond Ho, Jennifer Love, Ferenc Reinhardt, George W Bell, Jin Chen, Robert Weinberg, Dian Yang, Jonathan Weissman, Kipp Weiskopf. CD47 predominates over CD24 as a macrophage immune checkpoint in cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr A055.
Abstract A057: Therapeutic modality, antitumor efficacy and immune safety for targeting innate immune checkpoint TREX1 as cancer immunotherapy
Authors: Xing Cong , Tu Xintao , Huai Wanwan , Tang Zhen , Song Kun , Knox Kennady , Dobbs Nicole , Yang Kun , Yan Nan 
Published: October 2024

Abstract
Three-prime repair exonuclease 1 (TREX1) is the major DNase in mammalian cells that degrades cytosolic DNA to prevent activation of the cGAS-STING pathway. Genotoxic stress, DNA damage, and radiotherapy induce TREX1 expression in cancer cells, allowing them to evade innate immune activation of type I interferon (IFN-I)-mediated antitumor response. How TREX1 can be targeted for cancer immunotherapy remains elusive. Here, we report a high-throughput small-molecule inhibitor (SMI) screen of TREX1 using a cell-free DNase assay. We identify two lead compounds that inhibit TREX1 DNase activity at low micromolar concentrations, induce IFN-I signaling in cancer cells, and inhibit tumor growth in mice in an IFNAR-dependent manner. We further show that Trex1 knockout cancer cells elicit robust systemic antitumor immunity through tumor-intrinsic cGAS-STING activation and can be used as autologous cancer vaccines to protect against future tumor challenge. We also establish an inducible whole-body Trex1 knockout mouse model to simulate “on-demand” systemic TREX1 inactivation in adult mice. Sustained TREX1 loss in adult mice suppresses a broad range of solid tumors and metastatic tumors without incurring immune toxicity, demonstrating feasibility of an immune-safe therapeutic window. Together, our data present multiple therapeutic modalities for targeting TREX1 using SMIs and as an autologous cancer vaccine, as well as antitumor efficacy and immune safety, which should pave the way for developing TREX1-targeted cancer immunotherapy.
Citation Format: Cong Xing, Xintao Tu, Wanwan Huai, Zhen Tang1, Kun Song, Kennady Knox, Nicole Dobbs, Kun Yang, Nan Yan. Therapeutic modality, antitumor efficacy and immune safety for targeting innate immune checkpoint TREX1 as cancer immunotherapy [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr A057.
Abstract A058: Oncolytic adenovirus induces potent anti-tumor efficacy via robust activation of immune cells in bladder cancer
Authors: Kim Yunlim , Lim Bum Jin , Yoon A-Rum , Yun Chae-Ok , Kim Choung-Soo 
Published: October 2024

Abstract
Bladder cancer (BC) is one of the most prevalent malignancies globally. Despite recent advancements, resistance to conventional treatments such as surgery, chemotherapy, and immunotherapy remains common among BC patients. Thus, developing novel therapeutic agents or enhancing the efficacy of current treatments is essential for better management of BC. Oncolytic adenoviruses represent a promising new approach, capable of inflaming the tumor microenvironment and eliciting tumor-specific T cell responses. In this study, we aimed to understand the immune mechanisms involved in the antitumor therapeutic efficacy of oAd/IL-12/shVEGF—an oncolytic adenovirus co-expressing interleukin-12 (IL-12) and short hairpin RNA targeting vascular endothelial growth factor (shVEGF)—both in vitro and in vivo against BC. To investigate the therapeutic potential of oAd/IL-12/shVEGF in a syngeneic MB49 BC model, tumor-bearing mice were intratumorally injected with the oncolytic virus when tumors reached 70-100 mm³. Tumor volume and body weight were monitored until the end of the experiment. Mice were sacrificed when tumors reached 2000 mm³, and both tumor and spleen tissues were disaggregated for analysis. Tumor tissues were examined for proliferation marker (PCNA), adenovirus injection marker (E1A), and antitumor immune marker (CD8) using H&E and immunohistochemical analysis. To evaluate immune modulation, levels of IFN-γ, TNF-α, and IL-12 in tumor tissues and splenocytes were measured using ELISA kits. Tumor-specific immune responses were assessed by evaluating the number of IFN-γ-secreting immune cells in splenocytes via ELISPOT assay. Statistical analysis was performed using one-way ANOVA. Treatment with oAd/IL-12/shVEGF significantly suppressed tumor growth compared to PBS-treated controls. The oncolytic virus increased levels of IFN-γ, TNF-α, and IL-12 in both tumor tissues and splenocytes compared to PBS. Additionally, oAd/IL-12/shVEGF enhanced CD8+ T cell infiltration into tumor tissues and significantly reduced PCNA expression, indicating decreased tumor cell proliferation. Consistent with these findings, the number of IFN-γ-secreting immune cells was significantly higher in mice treated with oAd/IL-12/shVEGF compared to those treated with PBS. These results suggest that oAd/IL-12/shVEGF is a promising clinical cancer immunotherapeutic agent for inducing antitumor immunity in bladder cancer.
Citation Format: Yunlim Kim, Bum Jin Lim, A-Rum Yoon, Chae-Ok Yun, Choung-Soo Kim. Oncolytic adenovirus induces potent anti-tumor efficacy via robust activation of immune cells in bladder cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr A058.
Abstract A059: Uncovering Bystander Killing Mechanisms of Trastuzumab Deruxtecan (T-DXd): Effective Extracellular Payload Release via Cathepsin L in HER2-low Breast Cancer.
Authors: Tsao Li-Chung , Wang John S. , Ragusa Joey , Liu Bushangqing , McBane Jason , Spasojevic Ivan , Fan Ping , Trotter Timothy N. , Lyerly Herbert Kim , Hartman Zachary C 
Published: October 2024

Abstract
Trastuzumab deruxtecan (T-DXd), or fam-trastuzumab-deruxtecan-nxki, is a novel antibody-drug-conjugate (ADC) targeting HER2 that has demonstrated profound clinical efficacy across HER2-positive breast cancer (BC), including in HER2-low and HER2 “ultra-low” BC. However, the precise mechanism underlying its efficacy in HER2-low BC is still poorly understood. To determine the mechanism of DXd release and cytotoxicity, we compared in vivo T-DXd treatment of human BC xenografts with varying HER2 expression profiles, coupled with in vitro bystander killing analysis of co-cultured HER2-negative cells, and liquid chromatography–mass spectrometry of DXd payload levels in the tumor microenvironment. Our findings revealed that the efficacy of T-DXd in HER2-low and HER2-negative BC is mediated by extracellular proteases, specifically cathepsin L (CTSL), but not cathepsin B, within the tumor microenvironment (TME). Unlike traditional ADCs such as trastuzumab emtansine (T-DM1), which contain a non-cleavable linker and require efficient intracellular endocytosis for payload release and cytotoxicity, HER2-low and HER2 “ultra-low” BC demonstrated limited ADC uptake. Despite this, these cancer types exhibited strong sensitivity to T-DXd in vivo, but not to T-DM1. Critically, using CTSL overexpression and knockout strategies on HER2 “ultra-low” MDA-MB-231 cells, we found that extracellular CTSL released by tumor cells mediates the proteolytic cleavage of T-DXd’s linker. This enables broader DXd payload release and cytotoxicity, bypassing traditional ADC-resistance mechanisms, including HER2 downregulation and resistance to ADC internalization. Our studies reveal a crucial payload release mechanism of T-DXd within the TME, mediated by extracellular CTSL cleavage of T-DXd’s tetrapeptide linker. This mechanism likely contributes to the broad efficacy of T-DXd in HER2-low and even HER2 “ultra-low” BC over T-DM1. Collectively, our findings suggest that CTSL and other extracellular proteases in the TME may serve as important biomarkers for predicting T-DXd efficacy.
Citation Format: Li-Chung Tsao, John S. Wang, Joey Ragusa, Bushangqing Liu, Jason McBane, Ivan Spasojevic, Ping Fan, Timothy N. Trotter, Herbert Kim Lyerly, Zachary C Hartman. Uncovering Bystander Killing Mechanisms of Trastuzumab Deruxtecan (T-DXd): Effective Extracellular Payload Release via Cathepsin L in HER2-low Breast Cancer. [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr A059.
Abstract B002: HIF-2A inhibition in adaptive immunity against cancer growth
Authors: Frazier Katya , Muise Eric , Stolz Joshua , Fischer Lukas , Buchanan Mark , Schneider Charlie , Ho Chan Brian Pak , Carr Richard , Perini Rodolfo , Long Brian , Linn Douglas 
Published: October 2024

Abstract
Hypoxia Inducible Factors (HIFs) are transcription factors implicated in many cellular processes key to survival, proliferation, and function, particularly for cancer cells. HIF2A has been identified as an oncogene in the context of renal cell carcinoma (RCC), and belzutifan (MK-6482) is a HIF2A inhibitor that is FDA-approved for VHL-associated and advanced RCC. HIF1A and HIF2A are expressed by all cells in the hypoxic tumor microenvironment, including anti-tumor immune cells, and have been shown to drive T cell effector function. Several ongoing clinical trials are evaluating MK-6482 in combination with immune checkpoint blockade therapy for advanced RCC, however the potential impact that MK-6482 may directly have on the adaptive immune response remains poorly understood. Considering the functional link between HIF signaling and T cell function, we explored whether HIF-2A inhibition by MK-6482 could impact activation and/or anti-tumor action of T cells supported by anti-PD-1 and anti-CTLA-4 immune checkpoint blockade. Interrogation of primary T cell activation by mixed lymphocyte reaction revealed that MK-6482 did not induce significant changes in cytokine secretion or cell proliferation with or without immune checkpoint blockade, despite evidence of HIF2A protein reduction. MK-6482 in combination with immune checkpoint blockade increased antitumor efficacy compared to either alone in an RCC humanized mouse model, resulting in almost complete tumor regression. IHC analysis of tumors revealed a trend of increased T cell infiltration and a significant reduction in HIF2A protein following combined treatment, potentially contributing to the tumor regression. mRNA sequencing of tumors also revealed increased expression of T cell activation pathways, suggesting that the combination treatment induced greater anti-tumor activity of infiltrating T cells. Together, our data support continued clinical evaluation of belzutifan and checkpoint blockade combination treatment for RCC, and we continue to explore the potential mechanistic effects by both in vivo and in vitro follow-up studies.
Citation Format: Katya Frazier, Eric Muise, Joshua Stolz, Lukas Fischer, Mark Buchanan, Charlie Schneider, Brian Pak Ho Chan, Richard Carr, Rodolfo Perini, Brian Long, Douglas Linn. HIF-2A inhibition in adaptive immunity against cancer growth [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr B002.
Abstract B025: A T cell engager targeting cancer associated fibroblasts inhibits tumor growth and modulates the tumor microenvironment
Authors: Tagore Joshua , Norgard Robert , Penikalapati Sia , Bachmayr-Heyda Anna , Budhani Pratha , Corrales-Pecino Leticia , Kashyap Abhishek , Xia Youli , O'Brien Sarah 
Published: October 2024

Abstract
Fibroblast activating protein (FAP) is an attractive target for therapeutic intervention being mainly expressed in malignant tissues. Previous studies have targeted FAP using a variety of methods yet failed in clinics. Here, we utilize FAP-targeted T cell engager (TcE) in KPCY tumor models to recapitulate a pre-clinical environment. The use of FAP- TcE efficiently depleted FAP+ fibroblasts in vitro and in vivo from tumors. This resulted in bystander killing of tumor cells and tumor growth control in vivo. This therapeutic effect was not dependent on priming via lymph node activation as shown in other publications. To understand the complex interactions with FAP expression, we perform comprehensive single cell RNA-sequencing profiling before and after FAP-TcE depletion to understand the pivotal genetic roles of FAP depletion in all cell types. This analysis initially revealed a T cell exhaustion phenotype with upregulated of PD-1 on T cells after FAP-TcE treatment. However, while addition of anti-PD-1 therapy significantly enhanced tumor efficacy, complete control was absent. RNA sequencing of the fibroblasts identified depletion of a myCAF-like fibroblast and an outgrowth of a mixed CAF population with phenotypes of both myCAF and iCAF. This population correlated with tumor growth, and cell cycle gene signatures. Future work will investigate the implications of this fibroblast population’s role in subverting immune suppression.
Citation Format: Joshua Tagore, Robert Norgard, Sia Penikalapati, Anna Bachmayr-Heyda, Pratha Budhani, Leticia Corrales-Pecino, Abhishek Kashyap, Youli Xia, Sarah O'Brien. A T cell engager targeting cancer associated fibroblasts inhibits tumor growth and modulates the tumor microenvironment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr B025.
Abstract B031: TCR signal strength drives tumor-specific CD8 T cell differentiation
Authors: Carson Sandra , Schietinger Andrea 
Published: October 2024

Abstract
Immunotherapies, such as immune checkpoint blockade, demonstrate the potential power of CD8 T cells to eliminate cancer cells, however these strategies only work in a subset of patients and tumor types. To design predictably effective immunotherapies, we must elucidate the mechanisms controlling tumor-specific T cell dysfunction and therapeutic reprogramming. TOX is a key transcription factor driving T cell differentiation in progressing tumors and required for T cell persistence. T cell receptor (TCR) signal strength (determined by the affinity of TCR for peptide-bound major histocompatibility complex (pMHC)) is known to regulate T cell differentiation during infections. However, how TCR signal strength impacts TOX expression and differentiation in tumors is less clear. Here, we developed a novel autochthonous mouse cancer model in which we can vary TCR signal strength to span the range observed for human tumor-infiltrating T cells and track tumor-specific CD8 T cells over several months from tumor initiation until end-stage cancer progression: we cloned a Sleeping Beauty transposon/transposase-based vector (SB-Cre) encoding Cre-recombinase and a fluorescent reporter protein fused to a tumor model antigen (OVA) under the control of the liver-specific albumin promoter. Through single amino acid substitutions of the native OVA sequence, we generated altered peptide ligands that are recognized by OVA-specific CD8 T cells with varying TCR signal strength. SB-vectors were delivered via hydrodynamic tail vein injection into mice with inducible activating oncogenes and silencing of tumor suppressor genes, a highly-efficient method to induce liver tumors. Over the course of tumor development we phenotypically and functionally characterized tumor-specific CD8 T cells in tumor draining lymph nodes (tdLN) and progressing liver tumors. Our data reveal how TCR signal strength determines TOX-driven differentiation and dysfunction of tumor-specific T cells starting at the earliest stages of tumorigenesis in tdLN. Ongoing efforts aim to investigate the functional impact of TCR signal strength on T cell differentiation and anti-tumor responses, including responsiveness to immunotherapeutic interventions.
Citation Format: Sandra Carson, Andrea Schietinger. TCR signal strength drives tumor-specific CD8 T cell differentiation [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2024 Oct 18-21; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2024;12(10 Suppl):Abstract nr B031.