bluuebunny/crossref_metadata_2025_split huggingface dataset:
Abstract B31: Combination inhibitor strategies targeting KRAS effector signaling in KRAS-mutant pancreatic cancer
Authors: Ozkan-Dagliyan Irem , Goodwin Craig M. , Bryant Kirsten L. , George Samuel D. , Lucas Kelly , Gautam Prson , Wennerberg Krister , Cox Adrienne D. , Der Channing J. 
Published: June 2021

Abstract
With KRAS mutations found in 95% of pancreatic ductal adenocarcinoma (PDAC), an effective anti-KRAS therapeutic strategy is anticipated to make a significant impact on the treatment of PDAC. Among the major directions currently being pursued, inhibitors of KRAS effector signaling are believed to be the most promising. However, as monotherapy, effector inhibitors have not demonstrated significant activity and concerns with normal tissue toxicity remain. Combination inhibitor strategies are considered the best approach to overcome these limitations. To identify effector inhibitor-based combinations, we applied a 525-oncology drug screen to identify combinations that enhanced the cytotoxic activity of inhibitors of the RAF-MEK-ERK and the PI3K-AKT-mTOR effector pathways. While many cytotoxic combinations were identified with RAF effector pathway inhibitors, few were identified with PI3K pathway inhibitors. The same classes of inhibitors were identified with RAF, MEK and ERK inhibitors. In addition to inhibitors of the PI3K-AKT-mTOR pathway, microtubule, HDAC and HSP90 inhibitors synergistically enhanced RAF and ERK inhibitor antitumor activity. Addressing a basis for synergy, we found that the different combinations showed enhanced loss of MYC protein, a key ERK substrate. In summary, our studies identify promising effector inhibitor-based combinations for PDAC treatment.
Citation Format: Irem Ozkan-Dagliyan, Craig M. Goodwin, Kirsten L. Bryant, Samuel D. George, Kelly Lucas, Prson Gautam, Krister Wennerberg, Adrienne D. Cox, Channing J. Der. Combination inhibitor strategies targeting KRAS effector signaling in KRAS-mutant pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr B31.
Abstract B35: Discovery of K-Ras(G12D)-targeting peptide KRpep-2d and its optimization strategy
Authors: Sakamoto Kotaro 
Published: June 2021

Abstract
Mutated Ras proteins play important roles in cell differentiation, proliferation, and survival of various cancers, especially mutations at residue Gly12 where G12D in K-Ras is the most frequent mutation. Although over 30 years have passed since the discovery of mutated Ras in human cancers, effective drug targeting to Ras has not been marketed. Very recently, KRpep-2d, an artificial cyclic peptide, was discovered as a first selective inhibitor to K-Ras(G12D) by phage display technology. KRpep-2d possesses low nanomol level activity in cell-free assays and shows preferable target selectivity in cell-based assay. In this presentation, I review the biochemical activity, biophysical activity, and SAR of KRpep-2d. In addition, I will discuss a strategy to brush up KRpep-2d for its therapeutic use.
Citation Format: Kotaro Sakamoto. Discovery of K-Ras(G12D)-targeting peptide KRpep-2d and its optimization strategy [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr B35.
Abstract B47: Systems-level dissection of tumor-macrophage crosstalk in ovarian cancer resistance to MEK inhibition
Authors: Wang Stephanie J. , Miller Miles A. , Lauffenburger Douglas A. 
Published: June 2021

Abstract
Several subtypes of ovarian cancer are associated with dysregulated MAPK signaling, including low-grade serous ovarian carcinoma (LGSOC), yet targeted inhibitors of the MAPK pathway have shown relatively limited success in clinical trials for gynecologic malignancies. Here, we investigated whether this could be explained in part by crosstalk between ovarian cancer cells and neighboring tumor-associated macrophages (TAMs) within the tumor microenvironment. Using in vitro models, human ovarian cancer cell lines were mildly protected against MEK inhibitor-induced cell killing by transwell co-culture with alternatively activated (IL-4 stimulated), but not classically activated (LPS and IFN-gamma stimulated), primary monocyte-derived macrophages. We employed multiplexed bead-based immunoassays to acquire a compendium of over 1,200 phosphoprotein, cytokine, and growth factor measurements across combinations of 3 ovarian cancer cell lines and macrophages derived from 4 healthy peripheral mononuclear blood cell (PBMC) donors. Principal components analysis (PCA) and partial least squares regression (PLSR) revealed that compensatory receptor tyrosine kinase signaling occurs in tumor cells upon MEK inhibitor treatment, and that this is amplified upon co-culture with alternatively activated macrophages. Further work will determine if targeting these tumor-intrinsic and crosstalk effects in combination with MEK inhibition represents a potential therapeutic strategy.
Citation Format: Stephanie J. Wang, Miles A. Miller, Douglas A. Lauffenburger. Systems-level dissection of tumor-macrophage crosstalk in ovarian cancer resistance to MEK inhibition [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr B47.
Abstract B52: KRAS-IRF2 axis drives immune suppression and immune therapy resistance in colorectal cancer
Authors: Liao Wenting , Overman Michael , Boutin Adam , Kopetz Scott , DePinho Ron , Wang Alan 
Published: June 2021

Abstract
The precise biologic functions and mechanisms of oncogenic KrasG12D (Kras*) in therapeutic resistance, including immune therapy, are not understood. Here, utilizing a colorectal cancer (CRC) mouse model engineered with an inducible Kras* transgene and conditional null APC and Trp53 alleles (iKAP) that we recently established (Boutin et al., Gene & Development 2017), we observed that KRAS*-expressing invasive tumors possess a prominent immune-suppressive profile characterized by a preponderance of myeloid-derived suppressor cells (MDSCs). Integrated transcriptomic and genomic analyses identified the Interferon Regulatory Factor 2 (IRF2) gene as a key downstream target of KRAS* mediating tumor progression and immune suppression. Mechanistically, integrated transcriptomics, cytokine profiling and ChIP-seq analysis identified CXCL3 as a key direct target of IRF2, and pharmacologic inhibition of CXCL3 or its receptor CXCR2 resulted in suppression of MDSC migration and infiltration in KRAS*-expressing CRC tumors. Translational studies established that de novo anti-PD1 resistance of KRAS*-expressing tumors can be overcome by enforced IRF2 expression or by treatment with small-molecule CXCR2 antagonist SX-682. Correspondingly, CRC patient tumors with higher IRF2 expression show increased response to anti-PD1 therapy. This KRAS*-mediated immune suppressive mechanism provides a framework for patient selection and combination therapies to enhance the effectiveness of immune checkpoint blockade therapy in advanced CRC.
Citation Format: Wenting Liao, Michael Overman, Adam Boutin, Scott Kopetz, Ron DePinho, Alan Wang. KRAS-IRF2 axis drives immune suppression and immune therapy resistance in colorectal cancer [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr B52.
Abstract IA04: Targeting RAS for anticancer therapy
Authors: Campbell Sharon , Carey Leiah , Prakash Ajit , Clark Geoff , Scarry Sarah , Aube Jeff 
Published: June 2021

Abstract
RAS is the most frequently activated oncoprotein in human cancer. Mutations in KRAS are prevalent in pancreatic, colon, and lung cancer. Despite the need for anti-RAS therapies, there are no clinically successful targeted therapies for RAS. We will present efforts to characterize KRAS G12C covalent inhibitors and compounds that bind to the KRAS P1 pocket. In addition, the Clark lab (U. of Louisville) has identified novel small molecules that bind and directly inhibit RAS function. Uniquely, the current lead compound binds preferentially to the activated form of RAS. It blocks the interaction of RAS with downstream effectors and suppresses the transforming activity of RAS in soft agar assays. The best compounds give an IC50 of ~500 nM in vitro. The inhibitor is active in vivo and suppresses growth of RAS-driven xenografts in NRG mice. There is no detectable toxicity. We have initiated efforts to solve the structure of these inhibitors in complex with RAS, to characterize the nucleotide dependence as well as inhibition of RAS interactions with regulatory and effector proteins in vitro using X-ray crystallography in combination with NMR, biochemical, and bioactivity assays. Results from these analyses will aid in elucidating the specificity and the mechanism of action needed to optimize the inhibitors and facilitate development into a drug candidate.
Citation Format: Sharon Campbell, Leiah Carey, Ajit Prakash, Geoff Clark, Sarah Scarry, Jeff Aube. Targeting RAS for anticancer therapy [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr IA04.
Abstract IA13: Targeting redox dependencies in pancreatic cancer
Authors: Chio Iok In Christine , Oertlin Christian , Robert Francis , Chan Karina , Liberm Dana Kapellar , Santana Abram , Park Young , Larsson Ola , Pelletier Jerry , Tuveson David 
Published: June 2021

Abstract
Dysregulation of mRNA translation is a common feature of human cancers. As such, therapeutic agents that target components of the protein synthesis apparatus hold promise as anticancer drugs. We previously showed that protein synthesis is upregulated in Kras mutant pancreatic cancer cells in a manner that is redox-dependent (1). By modulating formation of the eIF4F complex, the PI3K/AKT and mTOR signaling pathways act as major regulators of global and mRNA-specific translation. Consistently, we observed that protein synthesis and the viability of pancreatic tumor organoids are selectively decreased by the pan-AKT inhibitor MK2206, an effect that was potentiated by co-treatment with the pro-oxidant BSO1. Treatment of KrasG12D;p53R172H;PdxCre (KPC) mice with this drug combination resulted in suppressed tumor kinetics and modest improvement in survival. Inhibition of AKT/mTOR blunts cap-dependent translation initiation but also perturbs a plethora of other cellular functions. We thus investigated more selective means of targeting the translation machinery that do not entail wholesale ablation of the AKT/mTOR pathway. The RNA helicase eIF4A initiates translation by unwinding highly structured 5′-untranslated regions (UTRs) in mRNAs. Using polysome profiling followed by deep sequencing, we found that the translation of eIF4A-sensitive mRNAs was selectively increased in Kras-mutant tumor versus normal organoids. The rocaglate, CR-13-1b, is a compound that selectively inhibits the eIF4A helicase and displayed high toxicity in Kras mutant tumor organoids, but not in normal organoids. Polysome sequencing revealed that CR131b selectively modulates translational efficiencies in tumor but not normal organoids. Interestingly, this included multiple mRNAs encoding proteins involved in mitochondrial activity and redox homeostasis. As a single agent, CR131b treatment in KPC mice effectively inhibited protein synthesis in vivo, resulting in a significant decrease in tumor kinetics in a short-term study and an improvement in survival in a longitudinal study.
Reference
1. Chio II et al. NRF2 promotes tumor maintenance by modulating mRNA translation in pancreatic cancer. Cell 2016;166:963-76, doi:10.1016/j.cell.2016.06.056.
Citation Format: Iok In Christine Chio, Christian Oertlin, Francis Robert, Karina Chan, Dana Kapellar Liberm, Abram Santana, Young Park, Ola Larsson, Jerry Pelletier, David Tuveson. Targeting redox dependencies in pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr IA13.
Abstract IA15: T-Cells targeting mutated RAS—clinical trials
Authors: Yang James , Hanada Kenichi , Rosenberg Steven 
Published: June 2021

Abstract
Durable complete regressions of metastatic cancers can be achieved by the transfer of in vitro expanded tumor-reactive T-cells. In patients with melanoma, this can be done by giving tumor-infiltrating lymphocytes (TIL) reactive with tumor-specific mutated antigens (“neoantigens”). Unfortunately, the vast majority of immunogenic neoantigens have been shown to be totally patient specific. One exception is that T cells recognizing mutated KRAS have been found in the TIL of multiple patients. In one patient with G12D-mutated colon cancer, these cells were grown and administered to that patient (after a course of preparative immunosuppression) and mediated regression of multiple pulmonary metastases. A single lesion that had lost its presenting MHC Class I allele grew and was resected, and the patient remains disease free over 2 years later. Other patients have demonstrated additional Class I and Class II presented epitopes from mutated RAS, although they have not yet been administered clinically. In an effort to develop standardized reagents to target common RAS mutations, HLA-A11 transgenic mice were immunized with peptides containing G12D and G12V RAS mutations and HLA-A11 restricted T cells isolated. Murine T-cell receptors specific for these mutated epitopes were cloned and when retrovirally introduced into human PBL, they conferred recognition of mutated RAS but not wild-type RAS. Such cells could cause regression of established palpable pancreatic cancer xenografts in NSG mice. Two clinical trials targeting the G12D and G12V RAS variants with T-cell receptor-engineered autologous PBL in any patient who is HLA-A11 are now open to enrollment. Future efforts are under way to expand the library of receptors to encompass additional RAS mutations, other HLA alleles, and other shared mutations in common driver oncogenes.
Citation Format: James Yang, Kenichi Hanada, Steven Rosenberg. T-Cells targeting mutated RAS—clinical trials [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr IA15.
Abstract IA17: Molecular mechanisms that regulate Raf kinase signaling
Authors: Morrison Deborah 
Published: June 2021

Abstract
Raf kinases are essential for normal Ras pathway signaling, and activating mutations in components of this pathway are associated with a variety of human cancers as well as a group of related developmental disorders known collectively as the RASopathies. Of the core pathway components, the mechanisms that modulate the Raf family kinases are by far the most complex, involving changes in subcellular localization, protein interactions, and phosphorylation/dephosphorylation events. In addition, like numerous other protein kinases, the Raf kinases can form dimers. Functional studies investigating the importance of Raf dimerization have revealed that Raf dimer formation is required for normal Ras-dependent Raf activation and for the biologic activity of many disease-associated Raf mutants. At the meeting, I will present recent work examining the regulatory differences among Raf family members and will discuss how these differences contribute to Raf-mediated disease signaling. I will also present studies investigating the effect that various therapeutic agents have on Raf regulatory interactions and will describe new approaches to disrupt Ras-Raf-MEK-ERK pathway signaling.
Citation Format: Deborah Morrison. Molecular mechanisms that regulate Raf kinase signaling [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr IA17.
Abstract IA18: Targeting K-Ras directly
Authors: Shokat Kevin 
Published: June 2021

Abstract
Somatic mutations in the small GTPase K-Ras are the most common activating lesions found in human cancer and are generally associated with poor response to standard therapies. Efforts to directly target this oncogene have faced difficulties due to its picomolar affinity for GTP/GDP and the absence of known allosteric regulatory sites (1). Oncogenic mutations result in functional activation of Ras family proteins by impairing GTP hydrolysis. With diminished regulation by GTPase activity, the nucleotide state of Ras becomes more dependent upon relative nucleotide affinity and concentration. This gives GTP an advantage over GDP and increases the proportion of active GTP-bound Ras. I will discuss the development of small molecules that irreversibly bind to a common oncogenic mutant, K-RasG12C (2). These compounds rely on the mutant cysteine for binding and therefore do not affect the wild-type protein (WT). Crystallographic studies reveal the formation of a new pocket that is not apparent in previous structures of Ras, beneath the effector binding switch-II region. These data provide structure-based validation of a novel allosteric regulatory site on Ras that is targetable in a mutant-specific manner.
References
1. Stephen AG, Esposito D, Bagni RK, McCormick F. Dragging Ras back in the ring. Cancer Cell 2014;25: 272–81.
2. Ostrem JM, Peters U, Sos ML, Wells JA, Shokat KM. Nature 2013;12796:503, 548–51.
Citation Format: Kevin Shokat. Targeting K-Ras directly [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr IA18.
Abstract IA25: Pancreatic cancer models and medicine
Authors: Tuveson David 
Published: June 2021

Abstract
Since the most common KRAS oncoproteins lack therapeutic antagonists, we utilized mouse and organoid models to discover new characteristics of oncogenic KRAS that could represent new therapeutic opportunities in pancreatic ductal adenocarcinoma (PDAC). Continuous oncogenic Kras expression is required in PDAC mouse models to support the characteristic desmoplastic stroma that impairs drug delivery, suppresses the immune response, and promotes tumor progression. We identified the secretion of Tgf-β and IL-1α by neoplastic cells as ligands that produce stroma by stimulating the differentiation of pancreatic stellate cells into myofibroblasts (myCAFs) and inflammatory fibroblasts (iCAFs), respectively. Mutual antagonism between these two ligands led to the spatial patterning of these two fibroblast populations, with myCAFs juxtaposed to neoplastic cells while iCAFs located more distantly. Genetic and pharmacologic perturbation of iCAFs support the role of this subpopulation in PDAC progression, nominating them as a cellular target in Kras-dependent PDAC. Secondly, taking a cell-intrinsic approach, we found that oncogenic KRAS induced BNIP3L/Nix to stimulate selective mitophagy. Nix induction restricted flux of glucose to the mitochondria and enhanced cellular redox control, and loss of Nix reverted these effects and decreased cell proliferation in vitro. Furthermore, loss of Nix markedly delayed progression of pancreatic cancer in vivo. Our results reveal the Kras-Nix mitophagy program as a new mechanism to promote aerobic glycolysis, redox homeostasis, and disease progression in KRAS-mutant pancreatic cancer, and motivate the exploration of methods to antagonize Nix pharmacologically.
Citation Format: David Tuveson. Pancreatic cancer models and medicine [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr IA25.
Abstract IA33: Development of effective therapies for neurofibromatosis type 1 and other pediatric RAS-driven tumors
Authors: Widemann Brigitte 
Published: June 2021

Abstract
The RAS pathway is critical for cell survival and development. More than 20% of all adult cancers and many of the most aggressive pediatric cancers are driven by sporadic mutations of the RAS family of genes. In spite of substantial efforts by academia and the pharmaceutical industry, no effective therapies targeting RAS-mutated cancers have been identified to date. RASopathies are genetic disorders characterized by germline mutations in RAS pathway genes. These syndromes, such as neurofibromatosis type 1 (NF1), Noonan syndrome (NS), cardiofaciocutaneous syndrome, and Costello syndrome (CS), have a widely variable incidence (1:1000 NS -1:300,000 CS), are usually first diagnosed in children, and exhibit a wide variety of manifestations including an increased risk of development of pediatric cancers such as sarcomas, leukemias, and CNS tumors (up to 42-fold increased risk compared to the general population). No approved medical therapies exist for RASopathies. Through the conduct of a longitudinal natural history study, preclinical studies in collaboration with extramural investigators, and early-phase trials, the NCI Pediatric Oncology Branch recently identified the MEK inhibitor selumetinib as the first active therapy for debilitating peripheral nerve sheath tumors called plexiform neurofibromas (PN) in NF1. The POB has identified and clinically characterized atypical neurofibromas (ANF) in NF1 as precursors to aggressive sarcomas called malignant peripheral nerve sheath tumors (MPNST). This has allowed for the development of targeted therapies and prevention strategies for these tumors. This example raises the possibility of developing effective therapies for manifestations of other RASopathies. Recent comprehensive molecular, epigenetic, and genomic studies have demonstrated the mechanisms of RAS pathway activation in several pediatric malignancies including rhabdomyosarcoma, relapsed neuroblastoma, gliomas, and leukemias. These studies will enable the development of clinical trials targeting these tumors more effectively.
Citation Format: Brigitte Widemann. Development of effective therapies for neurofibromatosis type 1 and other pediatric RAS-driven tumors [abstract]. In: Proceedings of the AACR Special Conference on Targeting RAS-Driven Cancers; 2018 Dec 9-12; San Diego, CA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(5_Suppl):Abstract nr IA33.