bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract 1029: Dissecting the mechanism of action targeting TNFR2 with a lignd blocking anti-TNFR2 antibody that elicits potent anti-tumor activity
Authors: Zhao Xiaofeng , Liu Xiaoqing , Gao Zhenna , Wang Mengyu , Li Wenjing , Pang Ran , Yang Wenqing , Cao Zhuoxiao , Tang Renhong 
Published: July 2021

Abstract
Tumor necrosis factor receptor-2 (TNFR2) is a TNF receptor superfamily member and has been reported to have restricted expression in the immune system, including potent suppressive Tregs, myeloid suppressor cells and endothelial cells. The therapeutic potential of targeting TNFR2 for cancers has been previously demonstrated but with conflicting data reported by different groups. In order to gain further insight into the mechanism of action (MoA) of targeting TNFR2, we used an anti-murine TNFR2 surrogate antibody (suAb) and tested its functional activities both in vitro and in vivo. suAb was able to bind murine TNFR2 with high sub-nanomolar affinity, in the meantime, it can also block the interaction between murine TNFα and TNFR2 at both protein and cellular levels. CD4+ T cells were isolated from spleens of wildtype Balb/c mice, the co-incubation of which with murine TNFα and IL-2 rendering the significant proliferation of Treg within the CD4+ T cell population. Addition of suAb can potently reduce Treg proliferation while downregulating the expression of TNFR2 on these Tregs. Further detailed analysis by using isolated mouse FoxP3+ Treg confirmed that suAb could effectively suppress murine Treg proliferation induced by TNFα and IL-2. In vivo, suAb treatment resulted in significant tumor growth inhibition across various syngeneic tumor models (CT26, EMT6 and LL/2) as single agent or when combined with anti-mPD-1 (CT26). Tumor infiltrating lymphocytes (TILs) analysis revealed dramatic increase of the effective-memory pool of both CD4+ and CD8+ T cells together with an significantly improved CD8/Treg ratio. In addition, treatment with suAb led to decreased expression of PD-1 on tumor infiltrating CD8+ T cells suggesting a potential relieved exhaustion phenotype after the treatment. Based on this careful MoA characterization, corresponding human anti-TNFR2 lead antibodies have been identified and are currently under development as potential novel treatment for cancer patients.
Citation Format: Xiaofeng Zhao, Xiaoqing Liu, Zhenna Gao, Mengyu Wang, Wenjing Li, Ran Pang, Wenqing Yang, Zhuoxiao Cao, Renhong Tang. Dissecting the mechanism of action targeting TNFR2 with a lignd blocking anti-TNFR2 antibody that elicits potent anti-tumor activity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1029.
Abstract 1047: Dual targeting of CK2 and MTOR as a novel therapeutic approach for high-risk B-cell acute lymphoblastic leukemia
Authors: Song Chunhua , Ge Zheng , Ding Yali , Tan Bihua , Dovat Elanora , Yang Yiping , Gowda Chandrika , Dovat Sinisa 
Published: July 2021

Abstract
Genomic defect and Casein Kinase II-mediated hyper-phosphorylation of Ikaros tumor suppressor cause the loss of function of Ikaros, and Ikaros dysfunction is characteristics of high-risk B-cell acute lymphoblastic leukemia (HR B-ALL) with poor prognosis. The increased activation of the PI3K/AKT/mTOR pathway is also observed in HR B-ALL and identifies mTOR as an attractive therapeutic target in HR B-ALL. Here, we report that Ikaros represses MTOR transcription and Ikaros' ability to repress MTOR in leukemia is impaired by oncogenic CK2 kinase. Treatment with the CK2 inhibitor, CX-4945, enhances Ikaros activity as a repressor of MTOR, resulting in reduced expression of MTOR in HR B-ALL. Thus, we designed a novel therapeutic approach that implements dual targeting of mTOR: direct inhibition of the mTOR protein (with rapamycin), in combination with Ikaros-mediated transcriptional repression of the MTOR gene (using the CK2 inhibitor, CX-4945). Combination treatment with rapamycin and CX-4945 shows synergistic therapeutic effects in vitro and in patient-derived xenografts from HR B-ALL. These data suggest that such therapy has the potential to reduce the death rate in HR B-ALL. The dual targeting of oncogene transcription, combined with inhibition of the corresponding oncoprotein provides a paradigm for a novel precision medicine approach for treating hematological malignancies.
Citation Format: Chunhua Song, Zheng Ge, Yali Ding, Bihua Tan, Elanora Dovat, Yiping Yang, Chandrika Gowda, Sinisa Dovat. Dual targeting of CK2 and MTOR as a novel therapeutic approach for high-risk B-cell acute lymphoblastic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1047.
Abstract 1069: Determining the effect of bazedoxifene in combination with chemotherapy on colon cancer cells
Authors: Dmello Rhynelle S. , Thilakasiri Pathum , Duscio Belinda , Poon Ivan , Ernst Matthias , Chand Ashwini 
Published: July 2021

Abstract
Inflammatory cytokines, such as interleukin-6 (IL-6) and IL-11, activate the signal transducer and activator of transcription 3 (STAT3), which drives the gene transcription of cellular processes attributed as hallmarks of cancer. High levels of these cytokines, in combination with driver mutations, facilitate tumour growth and progression in preclinical models of colon cancer. Previous studies in our laboratory identified bazedoxifene (BZA), currently approved for the treatment of osteoporosis, as a small molecule inhibitor of GP130 (the receptor common to the IL-6 family of cytokines), selectively suppressing IL-6 and IL-11 signalling to reduce colon and gastric cancer growth in vivo (Thilakasiri et al. EMBO Mol Med 2019). The aim of this study is to determine the key cellular mechanisms influenced by GP130 inhibition to mediate anti-tumour effects in colon cancer cells. Additionally, we assessed the combined effects of BZA with standard of care chemotherapy drugs on cell proliferation and apoptosis. Using LIM2405 and HT29 colon cancer cells, the combined effect of BZA, fluorouracil and oxaliplatin on inducing apoptosis in LIM2405 and HT29 colon cancer cells was analysed using flow cytometry and confirmed using Western blotting and DIC microscopy. The effects of BZA was further analysed on HT29 xenograft growth and metastasis in vivo. Levels of STAT3 activation in response to IL-11/STAT3 signalling was characterised by Western blotting. Our results demonstrated that combination treatment with BZA, fluorouracil and oxaliplatin significantly increased apoptosis in LIM2405 cells and BZA significantly induced apoptosis in HT29 cells. Our data showed that BZA inhibited GP130-dependent STAT3 activity in the human colon cancer cell line LIM2405 and HT29. BZA treatment sensitized cells to chemotherapy leading to increased apoptosis. BZA treatment also reduced both primary tumour and metastatic burden in vivo demonstrating that gp130 mediated STAT3 inhibition is an attractive target for the treatment of early stage and advanced stage colon cancer.
Citation Format: Rhynelle S. Dmello, Pathum Thilakasiri, Belinda Duscio, Ivan Poon, Matthias Ernst, Ashwini Chand. Determining the effect of bazedoxifene in combination with chemotherapy on colon cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1069.
Abstract 1082: Regorafenib resistance is associated with senescence-like phenotype and EMT in colorectal cancer (CRC)
Authors: Kehagias Pashalina , Krayem Mohammad , Kindt Nadège , Najem Ahmad , Vandeputte Caroline , Journé Fabrice , Awada Ahmad , Ghanem Ghanem E. , Hendlisz Alain 
Published: July 2021

Abstract
The introduction of the multi-targeted tyrosine kinase inhibitor (TKI) regorafenib in clinical routine improve patients' survival with metastatic CRC who failed to respond to standard therapies, however at the cost of significant toxicities. Moreover, patients' tumor exhibit heterogeneous responses and become resistant. Its mechanism of action remains largely unknown, challenging the selection of patients through the identification of clinically useful predictive biomarkers. This study aimed to explore the effects on human CRC cell lines of short- and long-term exposure to regorafenib and investigate resistance-related mechanisms. Two representative CRC cell lines were used, HCT-116 and SW480. Short-term (3 days) and long-term exposure to IC50 values (HCT-116, 3µM and 6µM; SW480, 5µM and 6µM respectively) were intended to explore intrinsic and acquired resistance. The observation of early morphological changes (increased cell volume) in SW480 cells after regorafenib exposure led us to investigate a drug-initiated senescence-like phenotype commonly associated with resistance to treatment allowing cell death escape. These cells acquired stable senescent-like properties (slow-cycling cells, high β-galactosidase activity) and the majority of them were arrested in the G2/M cell cycle phase after long treatment exposure. A specific senescence-associated secretome (high sIL6Rα in cell supernatants) was also observed. In contrast, HCT-116 cells exposed to regorafenib presented early senescent features (high β-galactosidase activity) but developed over time an acquired resistance triggering EMT (high migration activity, upregulation of EMT-related factors) also known to contribute to TKI resistance. Moreover, the investigation of MAPK and PI3K/AKT pathways pointed to the latter as a significant player in acquired resistance of HCT-116 cells (increase of AKT phosphorylation) possibly related to the presence of a PI3KCA mutation in this cell line. Our findings provide new insights into the phenotypic plasticity of CRC cells under treatment pressure able to (1) either acquire stable senescent-like properties or (2) use early senescence state to undergo EMT. Our findings need further investigations of the major determinants involved in regorafenib-induced phenotype-switching and may help to develop new therapeutic strategies to overcome related resistances.
Citation Format: Pashalina Kehagias, Mohammad Krayem, Nadège Kindt, Ahmad Najem, Caroline Vandeputte, Fabrice Journé, Ahmad Awada, Ghanem E. Ghanem, Alain Hendlisz. Regorafenib resistance is associated with senescence-like phenotype and EMT in colorectal cancer (CRC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1082.
Abstract 1086: Pancreatic cancer musters HER2 signaling through DUSP6 to circumvent therapeutic MAPK inhibition
Authors: Bulle Ashenafi Shiferaw 
Published: July 2021

Abstract
Background: Oncogenic KRAS is present in almost all cases of pancreatic ductal adenocarcinoma (PDAC). The mitogen-activated protein kinase (MAPK) pathway is the most cardinal signaling cascade utilized by KRAS, but targeting RAF or MEK, the key signaling nodes within this pathway has been clincally unsuccesful, largely due to ERK reactivation. Targeting ERK kinases has recently emerged as a promising therapeutic strategy, with several ERK inhibitor combinations now ongoing in clinical trials. However, resistance to ERK inhibitionn is inevitable and should be investigated.
Aim: Identify adaptive mechanisms that can be targeted to potentiate ERK inhibitors in PDAC to facilitate development of novel therapeutic combinations.
Methods: Reverse-phase protein array (RPPA) was used in early-passage patient-derived cell lines (PDCLs) to identify potential resistance mechanisms. These were confirmed using RNA interference and overexpression in PDAC cell lines and PDCLs. The promising combinations were tested in heterotypic spheroid cultures and in 30 early-passaged PDAC patient-derived xenografts (PDXs).
Results: RPPA showed dramatic downregulation of DUSP4 and DUSP6 protein levels following MEK and ERK inhibition in PDAC cells, which coincided with phospho-activation of HER2 and HER3. Knockdown of DUSP6, but not DUSP4, was sufficient in activating HER2. Conversely, overexpression of DUSP6 curbed HER2 and ERK activation. Combined ERK inhibitor (ulixertinib) and bortezomib was able to prevent DUSP4 and DUSP6 downregulation in vitro but was ineffective in curbing in vivo tumor growth. On the other hand, ulixertinib plus PI3K or pan-HER inhibitor afatinib is effective in PDCLs in vivo. Addition of gemcitabine greatly augmented the therapeutic efficacy of these combinations and achieved prolonged tumor suppression in several PDX models.
Conclusions: Our study provided novel mechanisic insight on how PDAC cells evade MAPK inhibition via mustering HER2 signaling, as well as rational therapeutic combinations that can be readily tested in clinical trials.
Keys: DUSP6, HER2, KRAS, pancreatic ductal adenocarcinoma, therapeutic resistance
Citation Format: Ashenafi Shiferaw Bulle. Pancreatic cancer musters HER2 signaling through DUSP6 to circumvent therapeutic MAPK inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1086.
Abstract 1102: Integrated approach towards defining mechanism based combinations to guide clinical development of glutaminase inhibitors
Authors: Kovacs Jeffrey J. , Spencer Nakia D. , Bristow Christopher A. , Carugo Alessandro , Giluiani Virginia , Miller Meredith A. , Harris Angela , Feng Ningping , Soth Michael L. , Le Kang , de Stanchina Elisa , Rudin Charles M. , Draetta Giulio , Yap Timothy A. , Jones Philip , Heffernan Timothy 
Published: July 2021

Abstract
Metabolic dysregulation is a hallmark of cancer, and recently, increasing evidence has shown a critical role for glutamine metabolism to support the bioenergetics and biosysnthetic needs of tumor and immune cells. We have previously disclosed the development of the GLS1 inhibitor, IPN60090, which is currently advancing through Phase 1 clinical studies (NCT03894540). Metabolic plasticity has been suggested to confer adaptive resistance to metabolic inhibitors and defines mechanisms that could be exploited to enhance therapeutic benefit. To address the clinical problems of innate drug resistance and adaptation, we interrogated metabolic and adaptive responses to IPN60090 in vitro and in vivo. We and others have previously identified KEAP1/NFE2L2 mutant non-small cell lung cancer models as sensitive to GLS1 inhibition. Through an integrated approach, including metabolic, transcriptomic, and proteomic analysis, we have identified molecular pathways that confer resistance to GLS1 inhibition. Nodes in these pathways that drive aquired resistance, may serve as additional patient stratification biomarkers in subsets on NSCLC or provide opportunites for further drug development. Additionally, unbiased in vivo functional genomics screening identified mulitple signaling pathways that act as critical nodes governing resistance to GLS1 inhibition. Drug combinations were tested in vitro and in vivo to identify those that are most synergistic with IPN60090. We found that PI3K/AKT/mTOR signaling is a major contributor to IPN60090 resistance, and we demonstrate that dual targeting of GLS1 and PI3K/AKT/mTOR signaling in tumors with KEAP1/NFE2L2 mutations results in synergistic anti-tumor efficacy. IPN60090, dosed in combination with inhibitors of these pathways yields regressions and off-treatment, durable responses in preclinical models of KEAP1-mutant NSCLC. Based on these data, combination strategies are being developed for Phase 1b expansion cohorts.
Citation Format: Jeffrey J. Kovacs, Nakia D. Spencer, Christopher A. Bristow, Alessandro Carugo, Virginia Giluiani, Meredith A. Miller, Angela Harris, Ningping Feng, Michael L. Soth, Kang Le, Elisa de Stanchina, Charles M. Rudin, Giulio Draetta, Timothy A. Yap, Philip Jones, Timothy Heffernan. Integrated approach towards defining mechanism based combinations to guide clinical development of glutaminase inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1102.
Abstract 1115: BET bromodomain inhibition synergizes with MEK inhibitors in uveal melanoma
Authors: Ambrosini Grazia , Musi Elgilda , Schwartz Gary K. 
Published: July 2021

Abstract
Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. Approximately 50% of the patients develop hepatic metastasis and the median survival rate is 12 months. Currently available drugs have shown limited clinical activity in patients with UM and there is an urgent need for new effective therapies. UM is characterized by activating mutations of G protein q/11, mutations in BAP1, and amplification of the oncogene MYC. Epigenetic dysregulation plays a critical role in UM pathogenesis, and we have demonstrated that Gnaq/11 mutant UM cells are addicted to BRD4 activity. BRD4 is a key regulator of transcriptional elongation by recruiting positive transcriptional elongation factor complex (PTEFb) to chromatin and activating RNA polymerase II-dependent transcription. While BET inhibitors have shown potent activity in pre-clinical studies, single-agent BET inhibitors exhibited limited efficacy in advanced UM clinical trials. MAPK signaling in constitutively active in Gnaq/11 mutant UM cells and previous studies have shown that the MAPK pathway mediates resistance to BET inhibition. Therefore, we sought to combine MEK and BET inhibitors in a panel of UM cells. We found synergistic activities with a variety of structurally distinct MEK inhibitors including trametinib and binimetinib in combination with BET inhibitors, such as I-BET and PLX2853. These combinations induced a greater reduction in cell viability and significant apoptosis compared to either monotherapy, in both parental and BET inhibitor-resistant cells. Western blot studies were performed to evaluate the mechanism of the combination treatment with BET and MEK inhibition and demonstrated a marked downregulation of p-ERK, MYC, Bcl-xL and upregulation of BIM with the combination therapy. Similarly, the combination treatment resulted in greater inhibition of tumor growth compared to either BET or MEK inhibition alone in a Gnaq mutant xenograft model. In conclusion, our studies suggest that co-targeting of MEK and BET proteins may be required to maximize the responses of UM cells to BET inhibitors. Clinical trials with the combination of BET and MEK inhibitors are warranted.
Citation Format: Grazia Ambrosini, Elgilda Musi, Gary K. Schwartz. BET bromodomain inhibition synergizes with MEK inhibitors in uveal melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1115.
Abstract 1149: Nuclear receptor 4A1 (NR4A1) antagonists target PD-L1 in colon cancer
Authors: Mohankumar Kumaravel , Karki Keshav , Safe Stephen , Abdelrahim Maen 
Published: July 2021

Abstract
The nuclear orphan receptor 4A1 (NR4A1, Nur77, TR3) is overexpressed in multiple solid tumors including colorectal tumors and is a negative prognostic factor for patient survival. NR4A1 is expressed in colon cancer cells and exhibit pro-oncogenic activity and results of examination of several colon cancer cell lines show that PD-L1 expression is limited and NR4A1 and PD-L1 are co-expressed in SW480 and RKO colon cancer cell lines. Previous studies in breast cancer cells showed that PD-L1 was regulated by NR4A1 which activates transcription factor Sp1 bound to the PD-L1 gene promoter. Knockdown of NR4A1 or Sp1 by RNA interference or treatment with mithramycin an inhibitor of Sp-mediated transcription decreased expression of PD-L1 in RKO and SW480 colon cancer cell lines. These data coupled with ongoing gene expression and PD-L1 promoter studies demonstrate that PD-L1 expression is regulated by NR4A1/Sp1 in colon cancer cells. Bis-indole derived NR4A1 ligand that act as receptor antagonists have been developed in this laboratory and these compounds block pro-oncogenic NR4A1-regulated genes/pathways. Treatment of RKO and SW480 colon cancer cell lines with a series of potent 1,1-bis(3′-indolyl)-1-(3,5-disubstitutedphenyl) analogs decreased expression of PD-L1. These results show that bis-indole derived NR4A1 antagonists act as small molecule mimics of immunotherapeutics that target PD-L1. In vivo applications of NR4A1 ligands that target PD-L1 and their effects on tumor growth and immune surveillance are currently being investigated.
Citation Format: Kumaravel Mohankumar, Keshav Karki, Stephen Safe, Maen Abdelrahim. Nuclear receptor 4A1 (NR4A1) antagonists target PD-L1 in colon cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1149.
Abstract 1154: Site-specific gene editing with ABBIE for T-cell therapy
Authors: Park Jihyun , Wang Xiaohong , Mirandola Leonardo , Chiriva-Internati Maurizio 
Published: July 2021

Abstract
Therapeutic T-cell engineering using viral vectors has been extensively explored as the most promising therapeutic purpose. However, virus-mediated gene delivery carries many challenges and limitations, such as random insertion of transgene into chromosome, posing risk of oncogenic transformation of the host cells, and complexity in the manufacturing process.We are developing a gene-editing tool, ABBIE (A Binding-Based Integrase Enzyme) which combines the specificity of Cas9 with the non-destructive DNA integration conferred by HIV integrase. Unlike endonucleases, HIV integrase can efficiently insert LTR-flanked DNA without causing dsDNA breaks. In our system, by use of fusing protein of enzymatically dead Cas9 (Cas9DN) to integrase of HIV-1 or its mutants, we were able to perform the gene knock-out (KO) and knock-in (KI) in one step at the target genome loci. For proof of concept, we generated the ABBIE proteins and donor DNA containing fluorescent gene with LTR sequence and tested the ABBIE mediated knock-in with conversion of fluorescent proteins. The integration of fluorescent donor DNA into genome was observed in the 293 T-cells transfected with both WT and Mut ABBIE proteins. Higher integration rate was observed in the cells expressing Mut ABBIE protein. Further, we applied this strategy to deliver the donor fluorescent DNA or chimeric antigen receptors (CARs) via electroporation into the HPRT1 locus for specific insertion using primary human T cells. We observed an average of ~30% and ~16% knock-in efficiency as measured by flow cytometry of GFP+ and CD34+ expression, respectively. The site-specific transgene integration was tested by treating the cells with 6- thioguanine (6-TG). We will further optimize the electroporation condition to maximize editing efficiency. This novel therapeutic toolkit will provide a modular platform for inserting therapeutic genes safely and efficiently into the target genome, further accelerate the offshore immunotherapy development.
Citation Format: Jihyun Park, Xiaohong Wang, Leonardo Mirandola, Maurizio Chiriva-Internati. Site-specific gene editing with ABBIE for T-cell therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1154.