bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract P171: Ligand-displaying-exosomes using RNA nanotechnology for targeted delivery of multispecific drugs for liver cancer regression
Authors: Li Xin , Ellipilli Satheesh , Wang Hongzhi , Lee Wen-Jui , Ho Yuan Soon , Guo Peixuan 
Published: December 2021

Abstract
Liver cancer such as hepatocellular carcinoma (HCC) poorly responds to chemotherapeutics as there are no effective means to deliver drugs to liver cancer due to the intrinsic drug effluxion and detoxification properties of the liver. Exosomes are extracellular vesicles that deliver payload via a fusion mechanism to cell cytosol without endosome trapping. Here we report the use of GalNAc as ligands to decorate exosomes that loaded with anticancer therapeutics Paclitaxel (PTX) and miR122 that silence both the drug efflux pump MDR1 (multidrug-resistant protein-1) and the oncogenic gene ADAM10 (A Disintegrin and metalloproteinase domain-containing protein 10). GalNAc is the ligand that provides exosome targeting ability to bind the hepatocyte surface receptor ASGP-R (asialoglycoprotein-receptor) usually express on liver cancer cell surface abundantly. PTX is highly hydrophobic, when it is conjugated to a polymeric hydrophilic RNA as a prodrug, its water solubility increases 32000-fold. No toxicity was detected. The PTX conjugated RNA strands assembled into a 4-way junction RNA nanoparticle to harbor 24-copies of PTX and 1-copy of miR122. The 4WJ RNA nanoparticles are loaded into the exosome and are decorated with GalNAc as a targeting ligand using RNA nanotechnology. Binding studies demonstrated that the multispecific exosome selectively binds and internalizes into the HepG2 liver cancer cells, and delivers the PTX and miR122 into the cell cytosol, exhibiting the highest efficacy in killing the targeted cancer cells due to the multispecific effect comes from miR122, PTX, GalNAc, and Exos. The liver cancer tumor regressed significantly after systemic injection of the multispecific exosomes to mice xenograft-bearing liver cancer. The results demonstrate that exosomes can serve as a multivalent vector to carry ligands, RNAi, and chemical drugs as a multispecific strategy to treat incurable liver cancers.
Citation Format: Xin Li, Satheesh Ellipilli, Hongzhi Wang, Wen-Jui Lee, Yuan Soon Ho, Peixuan Guo. Ligand-displaying-exosomes using RNA nanotechnology for targeted delivery of multispecific drugs for liver cancer regression [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P171.
Abstract P177: NPEPPS regulates cisplatin-resistance and can be targeted to overcome treatment resistance in patient-derived bladder cancer tumoroids
Authors: Scholtes Mathijs P. , Akbarzadeh Maryam , Theodorescu Dan , Costello James C. , Mahmoudi Tokameh , Zuiverloon Tahlita C.M. 
Published: December 2021

Abstract
Gemcitabine/cisplatin combination is the recommended neoadjuvant chemotherapy (NAC) for muscle-invasive bladder cancer (MIBC) patients undergoing surgical removal of the bladder (cystectomy). Patients without residual tumor at cystectomy ,complete pathological response (pCR), have a good 5-yr OS of 80%. However, due to NAC resistance, only 25% of the patients achieve a pCR. This study aims to increase the number of patients reaching pCR by discovery and functional interrogation of novel and pharmacologically targetable mechanisms causal to NAC resistance. We have identified an M1 aminopeptidase, NPEPPS, to regulate intracellular cisplatin import through volume regulated anion channels (VRACs). We show that genetic inhibition of NPEPPS increases the intracellular concentrations of cisplatin, hereby re-sensitizing gem/cis-resistant BC cell lines. On the other side, NPEPPS over-expression enhanced resistance to cisplatin. Pharmacological inhibition of NPEPPS with tosedostat results re-sensitization of gem/cis resistant BC cells in vitro and in vivo. Additional therapeutically validation was performed in gem/cis resistant patient-derived tumoroids. For this purpose, tumoroid cultures were generated from bladder cancer patients whom did not respond to pre-operative gem/cis, molecularly characterized and compared to the tumor of origin. Comparison of bladder cancer specific hotspot mutations, copy-number aberrations and H&E staining confirmed that patient-specific tumor traits were maintained in ex vivo tumoroid cultures. Moreover, tumoroid cultures generated from NAC-resistant patients were also resistant to cisplatin concentrations that exceeded physiological serum concentrations. Interestingly, addition of NPEPPS-inhibitor tosedostat sensitized these NAC resistant tumoroids to serum concentrations of cisplatin. These findings have potential for rapid translation into the clinic and invite trials investigating tosedostat to overcome chemoresistance.
Citation Format: Mathijs P. Scholtes, Maryam Akbarzadeh, Dan Theodorescu, James C. Costello, Tokameh Mahmoudi, Tahlita C.M. Zuiverloon. NPEPPS regulates cisplatin-resistance and can be targeted to overcome treatment resistance in patient-derived bladder cancer tumoroids [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P177.
Abstract P180: Genetic screen identifies PDPK1 as a synergistic target to enhancing the efficacy of MEK1/2 inhibitors in NRAS mutant melanoma
Authors: Cai Weijia , Nguyen Mai , wilski nicole , purwin timothy , TiagodosSantos Manoela , Aplin Andrew 
Published: December 2021

Abstract
Melanomas frequently harbor activating NRAS mutations; however, there has been little advance in targeted therapy options for NRAS mutant melanoma patients. MEK inhibitors (MEKi) showed modest efficacy in clinic, which is insufficient to be approved by FDA. In this study, we performed a genome-wide CRISPR/Cas9-based screening, identified PDPK1 (Phosphoinositide-dependent kinase-1) as a therapeutic target to enhancing the efficacy of MEKi, and validated it in various NRAS mutant melanoma cell lines via pharmacological and genetic approaches. Combined inhibition of PDPK1 and MEK (PDPK1i+MEKi) profoundly inhibited NRAS mutant tumor growth in a xenograft model. Notably, the combinatorial treatment induced pyroptosis, and increased ratio of intratumoral CD8+ T cells, delayed tumor growth and prolonged survival in an immune competent allograft model whereas it showed a significantly weaker potency in an isogenic immune deficient model. These data suggest PDPK1i + MEKi is an efficient strategy against NRAS mutant melanoma in an immune-response-dependent manner. Significance: NRAS is still an 'undruggable' target in melanoma. Our discovery rationalizes the clinical development of PDPK1i plus MEKi in NRAS mutant melanoma patients and suggests further synergy of targeted therapy and immunotherapy.
Citation Format: Weijia Cai, Mai Nguyen, nicole wilski, timothy purwin, Manoela TiagodosSantos, Andrew Aplin. Genetic screen identifies PDPK1 as a synergistic target to enhancing the efficacy of MEK1/2 inhibitors in NRAS mutant melanoma [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P180.
Abstract P183: CRISPR screens identify sensitizers to trametinib in KRAS mutant cancer cell lines
Authors: Fenoglio Silvia , Cristo Aileen M. , Tepper James , Teng Teng , Meier Samuel R. , Choi Ashley , Zhang Hongxiang , Zhao Shan-chuan , Liu Shangtao , Ahronian Leanne G. , Aird Daniel , Das Nikitha M. , Yu Yi , Sjin Robert Tjin Tham , Andersen Jannik N. , Huang Alan , Li Fang , Pan Xuewen 
Published: December 2021

Abstract
KRAS is the most frequently mutated oncogene in human tumors and drives tumorigenesis across multiple lineages. Specifically, KRAS is mutated in about 30% of lung cancer and over 90% of pancreatic cancer. Despite recent progress in developing mutant selective KRASG12C inhibitors, patient treatment options for RAS activated cancers remain very limited. Targeting the MAPK pathway by means of MEK and ERK inhibitors has been explored as an alternative strategy for KRAS mutant cancer. However, the clinical benefit is modest due to drug resistance caused by reactivation of the MAPK pathway and potentially other pathways and/or bypass mechanisms. Here we used CRISPR-based screens to identify potential combination therapy targets to enhance trametinib response in KRAS mutant cancers. We screened in five KRAS mutant cell lines of lung and pancreatic lineages and identified both known as well as novel modulators of MEK inhibitor response. Consistent with previous reports, gene knockouts that impair the reactivation of ERK downstream of MEK inhibition scored as top hits in our drop-out screens. Knocking out MAPK1, RAF1, BRAF and PTPN11 sensitized all five cell lines to trametinib treatment supporting these as candidate drug combination targets for MAPK pathway inhibition. Our screens also identified multiple genes within the heparan sulfate pathway (EXT1, EXT2, EXTL3, XYLT2, ALG6, B3GAT3, B4GALT7 and HS2ST1) and the MAPK7 pathway (MAPK7 and MAP2K5) that sensitize multiple but not all cell lines to trametinib. As part of our target discovery platform, we further validated these screening results using various phenotypic assays. Altogether, our results suggest that resistance to MEK inhibitors is driven by reactivation of the MAPK pathway as previously demonstrated and that impairing such reactivation restores the sensitivity of KRAS mutant cancer cells to trametinib. The genetic mechanisms driving the MAPK pathway rebound are likely different in different cancers and understanding such mechanisms will be key for achieving clinical success.
Citation Format: Silvia Fenoglio, Aileen M. Cristo, James Tepper, Teng Teng, Samuel R. Meier, Ashley Choi, Hongxiang Zhang, Shan-chuan Zhao, Shangtao Liu, Leanne G. Ahronian, Daniel Aird, Nikitha M. Das, Yi Yu, Robert Tjin Tham Sjin, Jannik N. Andersen, Alan Huang, Fang Li, Xuewen Pan. CRISPR screens identify sensitizers to trametinib in KRAS mutant cancer cell lines [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P183.
Abstract P211: The investigational chemoprotection drug ALRN-6924, a dual inhibitor of MDMX and MDM2, shows potential for radioprotection
Authors: Annis Allen , Sutton David , Aivado Manuel , Vukovic Vojislav 
Published: December 2021

Abstract
Aim: We investigated whether p53 activation with ALRN-6924 can prevent toxicity in mouse models of acute radiation injury. Materials and methods: ALRN-6924 is a clinical-stage, first-in-class, stabilized cell-permeating alpha-helical peptide that disrupts the interaction of the p53 tumor suppressor protein with its endogenous inhibitors, MDMX and MDM2. In previous experiments it was shown that ALRN-6924 can induce transient, dose-dependent cell cycle arrest in the bone marrow to protect those cells from chemotherapy while not protecting p53-mutant cancer cells. Because radiation (like chemotherapy) preferentially affects proliferating cells, we hypothesized that ALRN-6924 may also protect proliferating cells in normal tissues from radiation-induced cellular toxicity. Cell cycle arrest was measured in the bone marrow of ALRN-6924-treated C57BL/6 mice by flow cytometry using EdU incorporation. Serum levels of macrophage inhibitory cytokine-1 (MIC-1), a biomarker of p53 activation, were measured by ELISA. Cell proliferation and apoptosis were measured in formalin-fixed mouse bone marrow by immunohistochemistry analysis of Ki67 and cleaved PARP, respectively. C57BL/6 mice (n=7/group) were treated with one or more intravenous 2.4 mg/kg doses of ALRN-6924 at 24, 16, 8, or 1 hour (or combinations thereof) or placebo prior to an abdominally targeted (shielded body) 15 Gy radiation dose and then monitored for body weight (BW). Results: MIC-1 was elevated in the serum of ALRN-6924-treated mice in a dose-dependent fashion. Repeated doses of ALRN-6924 every 8 hrs yielded sustained MIC-1 elevation, which correlated with reduced Ki67 positivity in the bone marrow. Treatment-dependent changes in cPARP expression were evident, but minimal in magnitude. In a nonlethal radiation exposure model, ALRN-6924 yielded significant protection from radiation-induced BW loss in a schedule-dependent manner. Placebo-treated mice showed 10% to 15% BW loss five days after irradiation, while mice receiving one or more ALRN-6924 doses 8 hrs prior to irradiation had an average of 4% BW loss (p=0.008, two-sided t test). Conclusions: ALRN-6924 mitigates toxicity in a mouse model of acute radiation injury. The observed radioprotection effect correlates with pharmacodynamic markers of cell proliferation and cell cycle arrest after one or more doses of ALRN-6924, and further supports previous demonstrations of chemoprotection with ALRN-6924. These results provide a rationale to investigate ALRN-6924 as a radioprotective agent.
Citation Format: Allen Annis, David Sutton, Manuel Aivado, Vojislav Vukovic. The investigational chemoprotection drug ALRN-6924, a dual inhibitor of MDMX and MDM2, shows potential for radioprotection [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P211.
Abstract P221: Discovery of a covalent inhibitor for an oncogenic mutant RhoAY42C
Authors: Guo Shirley , Cao Ping 
Published: December 2021

Abstract
Ras homolog family member A (RhoA) is a member of a larger family of Rho proteins of small GTPases, with structural and signaling similarities to Ras proteins. RhoA is involved in multiple cellular processes including cytoskeleton regulation and actin-myosin contractility, etc. Recent studies have shown that the most common RhoA mutation in diffuse gastric cancer (DGC), Y42C, causes a gain-of-function and is associated with the loss of the E-cadherin gene CDH (CDH1). Inhibitors of RhoAY42C could be promising agents for treating DGC that harbors CDH1 mutation/deletion. BridGene expressed RhoAY42C in cells, screened our proprietary covalent library against the RhoAY42C live cells, and employed our chemoproteomic platform IMTACTM (Isobaric Mass Tagged Affinity Characterization) to detect covalent labeling of the mutant RhoA protein. A pilot screening led to the successful identification of a covalent ligand of RhoAY42C, BGS1933. Mass spec analysis has confirmed the covalent modification of Cys42 in RhoA by BGS1933. Dose-dependent binding of BGS1933 to RhoAY42C was measured using an orthogonal fluorescence-based assay. The Cancer Genome Atlas (TCGA) study shows that ~1% DGC patients harbor the oncogenic mutant RhoAY42C. The discovery of a covalent inhibitor of RhoAY42C will enable us to validate the role of RhoAY42C in DGC and facilitate the development of new first-in-class targeted therapies for the treatment of gastric cancer.
Citation Format: Shirley Guo, Ping Cao. Discovery of a covalent inhibitor for an oncogenic mutant RhoAY42C [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P221.
Abstract P236: Targeting AXL/PDK1 signaling axis activates immunogenic cell death in liver cancer
Authors: Xie Yunong , Zhou Lei , Lin Cheuk Yin , Lee Terence , Ding Jin , Ma Stephanie , Tong Man 
Published: December 2021

Abstract
Hepatocellular carcinoma (HCC) is the most malignant form of primary liver cancers with poor prognosis. Majority of the cases are diagnosed in advanced stages where therapeutic options are limited and the response rates are low. There is an unmet clinical need for more effective therapeutic treatment. AXL is a receptor tyrosine kinase which belongs to the family of TAM receptors. Overexpression of AXL has been reported in multiple cancers, including HCC. We and others have also reported an up-regulation of AXL in sorafenib-resistant HCC. However, its role in regulating anti-tumor immunity in HCC is not fully understood. In this study, we observed an immunosuppressive gene signature in sorafenib-resistant HCC by RNA-Seq and pathway enrichment analysis. Genetic manipulation and pharmacological inhibition of AXL promoted immunogenic cell death in sorafenib-resistant HCC cells, as evident by increased surface calreticulin and HMGB1 secretion. PDK1, a key modulatory kinase downstream of AXL in the PI3K/Akt pathway, was also up-regulated in sorafenib-resistant HCC. Knockdown of PDK1 similarly led to an increased immunogenic cell death. In a sorafenib-resistant immunocompetent mouse HCC model, blockade of AXL with a selective AXL inhibitor increased tumor-infiltrating activated and proliferating CD8+ T cells, resulting in tumor suppression and prolonged survival of the mice. Taken together, our findings suggest that targeting the AXL/PDK1 signaling axis could be a viable therapeutic option which enhances anti-tumor immunity for the treatment of HCC.
Citation Format: Yunong Xie, Lei Zhou, Cheuk Yin Lin, Terence Lee, Jin Ding, Stephanie Ma, Man Tong. Targeting AXL/PDK1 signaling axis activates immunogenic cell death in liver cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P236.
Abstract P241: A highly potent HPK1 inhibitor augments immune cell activation and anti-tumor immunity in a syngeneic tumor mouse model
Authors: Liu Hao , Wu Lei , Feng Song , Huang Wei , Li Huijuan , Lin Jing , Liu Yangyang , Mei Liufeng , Ren Baoqi , Xie Julie , Yao Lili , Zhong Wenge 
Published: December 2021

Abstract
Background: HPK1 (MAP4K1) is a serine/threonine Ste20-related protein kinase that belongs to the mitogen-activated protein kinase (MAPK) family. HPK1 is mainly expressed in hematopoietic cells and serves as a negative regulator of anti-tumor immunity through modulating the activation of lymphocytes and dendritic cells. Upon TCR activation, HPK1 phosphorylates the adaptor protein SLP76 at Ser376 to destabilize the SLP76 microclusters, which leads to the attenuation of the TCR signaling. The reported anti-tumor efficacy data from HPK1 knockout and kinase-dead knock-in mouse models support HPK1 as a novel intracellular I/O target. Methods: Regor CARD platform (Computer Accelerated Rational Discovery) was deployed to identify potent and selective inhibitors of HPK1. Biochemical assays and primary human pan T cell-based cellular assays were utilized to support the structure-activity relationship (SAR) analysis and inhibitor optimization. In vitro and in vivo target engagement studies were conducted in Jurkat T cells and mouse splenocytes, respectively. In vivo efficacy study data were generated using CT-26 syngeneic tumor mouse model. Results: Highly potent HPK1 inhibitors with good selectivity against the liable immune kinases were identified. RGT-197, one of the lead inhibitors demonstrated a significant increase of IL-2 secretion in primary human pan T cells upon TCR activation. It inhibited TCR-induced phosphorylation of SLP76 at Ser-376 in vitro and in vivo. Anti-tumor efficacy was observed in CT-26 tumor-bearing mice by oral dosing of RGT-197 as a single agent and in combination with an anti-PD1-monoclonal antibody. Furthermore, RGT-197 increased the level of cytokines important for anti-tumor immunity in vivo. Conclusion: RGT-197, a potent and selective HPK1 inhibitor, provides a potential opportunity as a small molecule I/O agent to boost anti-tumor immunity either as monotherapy or in combination with immune checkpoint inhibitors.
Citation Format: Hao Liu, Lei Wu, Song Feng, Wei Huang, Huijuan Li, Jing Lin, Yangyang Liu, Liufeng Mei, Baoqi Ren, Julie Xie, Lili Yao, Wenge Zhong. A highly potent HPK1 inhibitor augments immune cell activation and anti-tumor immunity in a syngeneic tumor mouse model [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P241.
Abstract P254: Transcriptional effects in C26 tumor highlight mechanistic aspects of a novel dual MEK inhibitor, IMM-1-104
Authors: Kolitz Sarah E. , Fowler Kevin D. , King Peter J. , Zeskind Benjamin J. , Hall Brett M. 
Published: December 2021

Abstract
We developed a novel dual MEK inhibitor, IMM-1-104, that showed 94% tumor growth inhibition (TGI) in the syngeneic C26 mouse model through 10 days at 150 mg/kg (mpk) BID, with only 3.8% tumor-adjusted body weight loss (BWL) through 24 days. The mechanism differs from that of standard MEK inhibitors (MEKi), and leverages signaling dynamics to decouple efficacy and toxicity. IMM-1-104 achieves deep cyclic inhibition of the pathway rather than constant blockade, and prevents the RAF1 (CRAF) bypass which has hampered standard MEKi. In this study, we examined the transcriptional effects of IMM-1-104 in the C26 model via RNA sequencing. These observations confirmed the pattern of deep cyclic inhibition, demonstrating strong MAPK pathway inhibition in tumor 2h after treatment, and near complete release 12h following treatment. This pattern was observed both after the initial dose as well as following chronic BID dosing (18 days), indicating that deep cyclic inhibition was sustainable across chronic dosing. Filtering the transcriptional signatures to examine effects that followed the pattern of deep cyclic inhibition (strong effect at 2h and release at 12h) revealed effects on mitochondrial and metabolism genes. These genes included Hk2, which was downregulated more than 2-fold after 2h of treatment with 100 mpk IMM-1-104 both after the initial dose and following chronic BID dosing. The effect on Hk2 occurred in tumor but not in muscle tissue from the same mice. These results were independent of adaptive immunity, as they were also observed in nude mice. Top transcriptional effects of IMM-1-104 treatment in tumor also included an increase in expression of Wnt pathway genes at 2h, following either a single dose or chronic BID dosing, at both 25 and 100 mpk. This increase was also observed at 12h following the 100 mpk dose. Activation of Wnt signaling in CRC tumors has previously been reported with standard MEK inhibitors. The transcriptional profile of IMM-1-104 in the C26 model highlighted key aspects of its mechanism related to signaling dynamics, which helps explain its ability to achieve high TGI and tolerability. The profile also highlighted aspects shared with standard MEKi that could shed light on potential resistance pathways.
Citation Format: Sarah E. Kolitz, Kevin D. Fowler, Peter J. King, Benjamin J. Zeskind, Brett M. Hall. Transcriptional effects in C26 tumor highlight mechanistic aspects of a novel dual MEK inhibitor, IMM-1-104 [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P254.