bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract A149: A chemical screening and machine learning approach to de-convolve kinase addictions in TNBC
Authors: Gautam Prson , Al-Ali Hassan , Wennerberg Krister
Published: August 2018

Protein kinases are major regulators of cellular signalling and known drivers of cancer and other diseases. In the last two decades, kinase inhibitors have gained much attention as cancer therapeutic agents. In this study, we combined drug vulnerability data of 19 breast cancer cell lines with kinase activity data, and employed machine learning and information theory to de-convolve cell line specific kinase addictions. The study was mainly focused on triple-negative breast cancers (TNBC), which still lack targeted therapy. With this approach, we identified several novel TNBC cell line selective kinase addictions (e.g., FGFR2 for MFM-223) and, as added validation, detected previously established kinase sensitivities (e.g., BRAF in DU4475, ERBB2 in luminal cell lines SK-BR-3 and BT-474, along with generic addiction towards cell cycle and apoptosis regulators like PLK1 and PI3K). A major benefit of this approach is that it can identify readily druggable targets while avoiding false positives and undruggable candidates from loss-of-function analyses. Comparison of kinase inhibitor vulnerabilities with loss-of-function data showed significant discordance, highlighting the need for cautious evaluation of loss-of-function data for drug target identification. Our study underscores the heterogeneity of drug response in TNBC and provides a platform for rapidly identifying vulnerabilities and guiding targeted therapy regimens.

Citation Format: Prson Gautam, Hassan Al-Ali, Krister Wennerberg. A chemical screening and machine learning approach to de-convolve kinase addictions in TNBC [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A149.
Abstract A152: Emerging indications for kinase-targeted therapies: screening for new targets
Authors: Li Rick , Lai Shenshen , Mah Allan , Zhang Hong , Yan Jun , Marotta Anthony , Zhang Zaihui
Published: August 2018

Protein kinases play key roles in normal physiologic functions. Aberration of individual protein kinases and the pathways that these enzymes govern are centrally involved in the pathogenesis of a number of diseases including cancer, neurologic disorders, metabolic diseases, and autoimmune conditions. Targeting these enzymes using small-molecule approaches has been proven to be highly relevant in terms of treating cancer and, more recently, autoimmune conditions like rheumatoid arthritis. Evaluating the specificities of these compounds across the kinome and relating these effects with clinical manifestations may provide important insights into how these compounds can be used to treat other diseases. In this study, we evaluated the specificity of four compounds–saracatinib, vandetanib, crizotinib, and cabozantinib–across a panel of 48 kinases representing 7 major groups and other kinases. They were assessed at 1 and 10 µM using the “gold standard” radiometric assay. A 50% reduction in kinase activity at the single point concentration at 1 μM was deemed to be of relevance in this study as that would signify an IC50 of less than 1 µM. The study demonstrated that all four compounds inhibited greater than 30% of the kinases within this 48-kinase panel, albeit different kinase targets. Interestingly, none of the selected kinases within AGC, CAMK, and CGMC subgroups was inhibited more than 50% at 1 μM. Furthermore, all 4 inhibitors exhibited greatest potency against their intended kinase targets, mainly receptor and cytoplasmic tyrosine kinases, RTKs, and CTKs, respectively. Specifically, saracatanib inhibited PDGFR, KIT, EGFR, and BTK; vandetanib inhibited FGFR2 and KDR, an RTK that interacts with the ligand VEGF; crizotinib inhibited insulin receptor (InsR); and cabozantinb had effect on DDR2, FLT1, FLT3, KDR, MET, and TRKA. In conclusion, we have demonstrated the power of using unbiased protein kinase panels to uncover novel biochemical interactions with potential therapeutic values. Of the four inhibitors tested above, we have found several new targets for each, including an interaction between crizotinib and insulin receptor, an RTK involved in metabolic homeostasis. This opens up possible implications for crizotinib in regulating metabolic homeostasis.

Citation Format: Rick Li, Shenshen Lai, Allan Mah, Hong Zhang, Jun Yan, Anthony Marotta, Zaihui Zhang. Emerging indications for kinase-targeted therapies: screening for new targets [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A152.
Abstract A181: Alterations in the Rho pathway contribute to Epstein-Barr virus-induced lymphomagenesis in immunosuppressed environments
Authors: Cho Sung-Yup
Published: August 2018

Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphomas (EBV+-DLBLs) tend to occur in immunocompromised patients, such as the elderly or those undergoing solid organ transplantation. The pathogenesis and genomic characteristics of EBV+-DLBL are largely unknown because of limited availability of human samples and lack of experimental animal models. We observed the development of 25 human EBV+-DLBLs during engraftment of gastric cancer adenocarcinomas into immunodeficient mice. An integrated genomic analysis of the human-derived EBV+-DLBLs revealed enrichment of mutations in Rho pathway genes, including RHPN2, and Rho pathway transcriptomic activation. Targeting the Rho pathway using the ROCK inhibitor, fasudil, decreased tumor growth markedly in EBV+-DLBL patient-derived xenograft (PDX) models. Thus, alterations in the Rho pathway appear to contribute to EBV-induced lymphomagenesis in immunosuppressed environments.

Citation Format: Sung-Yup Cho. Alterations in the Rho pathway contribute to Epstein-Barr virus-induced lymphomagenesis in immunosuppressed environments [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A181.
Abstract A212: Preclinical efficacy of MEK inhibition in a K-Ras driven cholangiocarcinoma preclinical model
Authors: Dong Mingjie , Liu Xianqiong , Evert Katja , Utpatel Kirsten , Zhang Shanshan , Che Li , Gordan John , Calvisi Diego , evert Matthias , Liu Yan , Chen Xin
Published: August 2018

Intrahepatic cholangiocarcinoma (iCCA) is a form of deadly malignancy with limited treatment options. Gain-of-function mutations in KRAS are one of the most frequent mutations, found in ~25% of human CCA patients. MEK inhibitors have been developed and show some activity against solid tumors with Ras mutants. However, whether MEK inhibitors are effective against KRas mutant CCAs remains unknown. In the current study, we established a new mouse iCCA model (NICD/KRas) by expressing activated forms of Notch (NICD) and KRas (KRasV12D). We investigated the therapeutic potential of MEK inhibitors in vitro using human CCA cell lines and in vivo using KRasV12/NICD iCCA preclinical model. We found that in general, CCA cell lines with KRas mutations are more sensitive to MEK inhibitor U0126. Treatment of U0126 in KRas mutant CCA cells leads to increased apoptosis and decreased expression of pro-apoptosis gene Survivin. Furthermore, we found that treating KRasV12/NICD tumor-bearing mice with MEK inhibitor PD0325901 (PD901) resulted in stable disease. At molecular levels, PD901 efficiently inhibited p-ERK expression KRasV12/NICD tumor cells, leading to increased apoptosis. In summary, our studies demonstrate that KRasV12/NICD mice represent a novel and useful preclinical model to study KRas-driven CCA development. Our data further support the usefulness of MEK inhibitors for treatment of KRas mutant CCA in patients.

Citation Format: Mingjie Dong, Xianqiong Liu, Katja Evert, Kirsten Utpatel, Shanshan Zhang, Li Che, John Gordan, Diego Calvisi, Matthias evert, Yan Liu, Xin Chen. Preclinical efficacy of MEK inhibition in a K-Ras driven cholangiocarcinoma preclinical model [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A212.
Abstract B010: Antitumor cellular immune response elicited by Toca 511 and Toca FC therapy in preclinical and clinical studies
Authors: Montellano Tiffany T. , Ostertag Derek , Hogan Daniel J. , Diago Oscar R. , Gammon Dawn , Haghighi Ali , Accomando William , Mitchell Leah , Das Asha , Gruber Harry , Jolly Douglas J.
Published: August 2018

Toca 511 (vocimagene amiretrorepvec), in combination with Toca FC (5-FC; flucytosine extended-release tablets), is an investigational combination product currently under development for the treatment of high-grade glioma (HGG) and other solid tumors. Toca 511 is a gamma-retroviral replicating vector (RRV) delivering a cytosine deaminase transgene to infected cells to convert antifungal drug 5-fluorocytosine (5-FC) into antineoplastic drug 5-fluorouracil (5-FU). Toca 511 can be administered by multiple routes; selectively infects, spreads, and persists in cancer cells; and through multiple mechanisms of action can elicit an antitumor immune response. Treatment directly kills infected cancer cells. Diffusible 5-FU also kills neighboring susceptible cells that contribute to the immune-suppressed tumor microenvironment, especially myeloid immune suppressor cells. After multiple cycles of 5-FC, treated animals that clear tumor are resistant to tumor rechallenge. Adoptive transfer recipients of splenocytes from animals that previously cleared their tumor through treatment with Toca 511 and 5-FC experience a significant survival benefit compared to animals receiving spleen cells from naïve donors. Toca 511 and Toca FC have been administered to 126 recurrent high-grade glioma (rHGG) patients in three phase I studies (NCT01156584, NCT01470794, NCT01985256), and a phase 2/3 trial (Toca 5) is ongoing (NCT02414165). Toca 511 plus Toca FC has been well tolerated in these patients. In the clinical study presented, Toca 511 is injected into resection cavity walls at time of tumor resection, and followed with multiple courses of Toca FC. In a subset of phase I patients that mimic the phase 2/3 rHGG enrollment criteria, there were 3 complete responses and 2 partial responses out of 24 patients observed. The median duration of response is 26.7 months. These responders have an overall survival range from 24.0+ to 42.6+ months and ongoing. Data are consistent with induction of antitumor immune responses after Toca FC administration. Changes in peripheral immune populations as well as interrogation of immunogenic biomarkers in responding compared to nonresponding patients will be presented.

Citation Format: Tiffany T. Montellano, Derek Ostertag, Daniel J. Hogan, Oscar R. Diago, Dawn Gammon, Ali Haghighi, William Accomando, Leah Mitchell, Asha Das, Harry Gruber, Douglas J. Jolly. Antitumor cellular immune response elicited by Toca 511 and Toca FC therapy in preclinical and clinical studies [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B010.
Abstract B028: Beta 2-microglobulin promotes human pancreatic cancer cell migration
Authors: Sliker Bailee , Liu Cassie , Poelaert Brittany , Goetz Benjamin , Solheim Joyce C.
Published: August 2018

Beta 2-microglublin (β2m) is a 12-kilodalton protein that serves as the non-covalently bound light chain in complex with the major histocompability complex (MHC) class I heavy chain. The human MHC class I heavy chain is known as human leukocyte antigen (HLA), which exists in three isotypes (HLA-A, -B, and -C). Much of the known function of β2m is in regards to its role in stabilizing the HLA class I heavy chain and thereby helping to present endogenous antigenic peptides to cytotoxic T cells. Notably, β2m has recently been found to be elevated in expression in a variety of cancers, including renal cell carcinoma, oral squamous cell carcinoma, prostate cancer, lung cancer, breast cancer, and multiple lymphocytic malignancies. In most of these cancers, β2m is correlated with more advanced disease and poorer prognosis. It has also been shown that in some cancer models, such as a renal cell carcinoma and an oral squamous cell carcinoma model, β2m can affect the proliferation and migration of these tumor cells. The levels and effects of β2m in pancreatic cancer, however, have not been reported thus far. Recent results from our laboratory have revealed high expression of β2m in nearly all members of a panel of pancreatic cancer cell lines. To examine the functional role that β2m plays in pancreatic cancer, we used siRNA specific for β2m to decrease its expression in the mentioned panel of pancreatic cancer cell lines and evaluated migration by transwell assay. Our results showed that the migration of the tested pancreatic cancer cell lines significantly decreases when β2m expression is reduced. Furthermore, we found that when β2m levels are downregulated, there are corresponding decreases in the levels of the HLA-A and -B heavy chains and in the expression of amyloid precursor-like protein 2 (APLP2). Previous research from our laboratory has shown that β2m affects APLP2/MHC association and that reducing expression of APLP2 slows pancreatic cancer cell migration. Additionally, our current research demonstrated that downregulation of β2m expression reduces the steady-state level and the half-life of APLP2. In conclusion, our results indicate that β2m promotes the migration of pancreatic cancer cells and suggest that this effect may be mediated through stabilization of the HLA class I heavy chain and, secondarily, APLP2. These studies thus provide evidence of β2m as a potential target for novel therapies directed against pancreatic cancer.

Citation Format: Bailee Sliker, Cassie Liu, Brittany Poelaert, Benjamin Goetz, Joyce C. Solheim. Beta 2-microglobulin promotes human pancreatic cancer cell migration [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B028.
Abstract B045: Structure-activity relationship study of a novel PKC activator, vibsanin A, for induction of differentiation in leukemia cells
Authors: Simizu Siro , Matsuki Wataru
Published: August 2018

Background and Objective: Chemotherapeutic agents are widely used for acute myeloid leukemia (AML) treatment; however, their severe side effects in patients limit the clinical use of chemotherapy for AML. Differentiation-inducer such as PKC activators was expected to show therapeutic potentials, but many natural derived PKC activators, including phorbol 12-myrystate 13-acetate (PMA), act as tumor-promoting activity. Therefore, the development of differentiation inducing-agents may contribute to constructing the next-generation AML treatment. Vibsanin A (VibA) was recently reported to induce differentiation of myeloid leukemia cells by activating PKC and to prolong survival of mouse xenograft model; however, the detailed chemical feature of VibA remains unclear. In this study, to determine the key partial structure of VibA for its activity, we compared the activity of VibA analogs in the activation of PKC and differentiation of AML cells. Results: To know whether the analogs functioned as PKC activator similarly to VibA, we detected phosphorylation of ERK, which acts downstream of PKC, by Western blotting. As a result, only one analog (VibA-1) induced ERK phosphorylation in a dose-dependent manner like PMA and VibA; however, other analogs had no effect on ERK phosphorylation. We examined whether VibA-1-induced ERK phosphorylation was mediated by PKC activation as well as VibA. We treated with PMA of the cells for long term to downregulate PKC. VibA-1-induced ERK phosphorylation was suppressed by pretreatment with PMA for the long term, indicating that VibA-1 activated PKC, thereby ERK phosphorylation. These data suggested that only VibA-1 retained the ability to activate PKC, which was originally observed in VibA. We observed that VibA-1-treated THP-1 cells became adherent to the culture plate and showed considerable morphologic change. Moreover, several lines of evidences including increased cell size, lowered nuclear to cytoplasmic ratio, and highly vacuolated cytoplasm, characterized by Giemsa staining suggested, that VibA-1 triggered monocytic differentiation similarly to VibA. Thus, our results suggested that VibA and/or its analog VibA-1 may be a novel chemotherapeutic agent for treatment of AML.

Citation Format: Siro Simizu, Wataru Matsuki. Structure-activity relationship study of a novel PKC activator, vibsanin A, for induction of differentiation in leukemia cells [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B045.
Abstract B047: A novel and efficient therapeutic strategy to target β1 integrin in metastatic cells from different cancer types
Authors: Casal Ignacio , Bartolomé Ruben A. , Jaén Marta , Aizpurua Carmen , Calviño Eva , Imbaud Juan I.
Published: August 2018

Purpose: We aim to develop new therapeutic strategies to control advanced metastatic disease in cancer. We hypothesized that targeting α2β1 integrin activation with cadherin RGD blocking monoclonal antibodies is an efficient procedure to reduce metastatic spread in multiple tumors. Experimental Procedures: Monoclonal antibodies (mAbs) were generated against a 9-mer peptide containing the RGD motif and flanking sequences of CDH17 (aka LI-cadherin). Antibodies were tested for inhibition of β1 integrin activation, cell adhesion, proliferation and invasion assays using cell lines from different cancer types (KM12SM (colorectal), PANC1 (pancreatic), BLM (melanoma,) and MDA-MB-468 (breast)) expressing CDH17 and VE-cadherin. The impact of the CDH RGD-specific mAbs on cell signaling was assessed by Western blot. Swiss nude mice were used to generate liver and lung metastasis with colorectal and melanoma cancer cell lines. Results: CDH RGD-specific mAbs were prepared and characterized. They recognized CDH17 and VE-cadherin positive cells by immunoprecipitation, flow cytometry, and confocal microscopy. CDH RGD mAbs blocked β1 integrin activation in metastatic cancer cell lines from different cancer types, causing a significant reduction in cell adhesion and proliferation. Signaling events related with FAK, JNK, ERK, Src, and AKT phosphorylation were blocked by the mAbs at different extent, according to the cancer type. Finally, CDH RGD mAbs caused a significant and persistent survival in nude mice developing lung and liver metastasis after intravenous or intrasplenic cell inoculation. Conclusions: CDH RGD mAbs constitute a promising therapy to control metastatic spread in colorectal cancer, melanoma, and probably other tumors expressing CDH17, VE-cadherin, or related RGD cadherins.

Citation Format: Ignacio Casal, Ruben A. Bartolomé, Marta Jaén, Carmen Aizpurua, Eva Calviño, Juan I. Imbaud. A novel and efficient therapeutic strategy to target β1 integrin in metastatic cells from different cancer types [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B047.
Abstract B059: SETD2-PI3Kβ synthetic lethality
Authors: Terzo Esteban , Jansen Valerie M. , Chiang Yun-Chen , Rathmell Kimryn W.
Published: August 2018

Introduction: Renal cell carcinoma (RCC) is a high-risk and high-mortality cancer for which several new targeted therapies exist. However, responses of primary clear cell RCC (ccRCC) tumors and metastases to these targeted agents are variable, and complete responses are relatively uncommon, underscoring the need to identify reliable biomarkers to predict tumor behavior. Mutations in the tumor suppressor gene SETD2, encoding a lysine methyltransferase, occur in 3-16% of ccRCC tumors while the SETD2 protein deficiency rate has been reported to be as high as 34%. The phosphatidylinositide 3-kinases (PI3Ks) have emerged as important therapeutic targets for the treatment of solid and hematologic malignancies, including ccRCC. In this study, we determine the extent to which small-molecule inhibitors against the p110α, p110β, and p110δ isoforms of PI3K inhibit growth of RCC with SETD2 loss. Methods: RNAi oligonucleotides and small-molecule inhibitors targeting the p110α (BYL719), p110β (TGX221, AZD8186), and p110δ (idelalisib) isoforms of PI3K were tested against ccRCC cell lines with SETD2 loss. The effect of drugs on cell growth and survival was determined by (1) proliferation in monolayer, (2) 3D growth in Matrigel, and (3) cell migration in wound healing assay. Downstream signaling pathways were evaluated by immunoblot analysis. Results: Genetic and pharmacologic inhibition of p110β resulted in inhibition of ccRCC cell lines with SETD2 loss. ccRCC-derived SETD2 deficient (-/-) 786-O and A498 cells exhibited increased sensitivity to TGX221 (IC50 = 2.3 - 4.5 µM, respectively) and AZD8186 (IC50 = 1.79 - 0.24 µM, respectively) as compared to SETD2 proficient (+/+) 786-O cells (IC50 = >10 µM). Inhibition of the p110δ isoform alone had a modest effect on ccRCC cell growth and migration. Importantly, genetic (with siRNA) and pharmacologic (with BYL719) inhibition of p110α had no effect on the ccRCC cell lines. Inhibition of AKT with the small-molecule inhibitor MK2206 recapitulated the effects seen with AZD8186 in ccRCC cell lines with SETD2 loss, suggesting PI3Kβ mediates the synthetic lethality via AKT signaling in the context of SETD2 loss in ccRCC. Conclusions: Our work strongly suggests a synthetic lethal-type of interaction between PI3Kβ inhibition and SETD2 loss and offers a rationale for further translational and clinical investigation of small-molecule inhibitors of PI3Kβ in RCC. Xenograft studies are ongoing to investigate the in vivo efficacy of AZD8186.

Citation Format: Esteban Terzo, Valerie M. Jansen, Yun-Chen Chiang, Kimryn W. Rathmell. SETD2-PI3Kβ synthetic lethality [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B059.
Abstract B066: Unique roles of group I PAK isoforms in regulating MPNST cell viability
Authors: Semenova Galina , Stepanova Dina , Karchugina Sofiia , Dubyk Cara , Deyev Sergey , Lazar Alexander , Chernoff Jonathan
Published: August 2018

Group I p21-activated kinases (PAKs) include three members (PAK1, PAK2, and PAK3) that represent key components of several cell signaling networks. By transmitting growth factor-induced signals from Rho family GTPases, PAK1/2/3 regulate cytoskeletal dynamics, cell shape, and motility. Group I PAKs modulate several oncogenic and survival pathways and are thought to play a critical role in initiation and progression of certain tumor types. Although group I PAK members share significant sequence similarity, mechanism of regulation, and substrates, PAK isoforms show different gene expression patterns in tissues and play unique functions in development and immune responses. While the described PAK1/2/3 functions in tumorigenesis are generally assigned to PAK1, there are increasing hints of isoform-specific roles for group I PAKs in cancer. We have recently demonstrated that PAK1/2/3 signaling is upregulated in malignant peripheral nerve sheath tumors (MPNSTs) and that small-molecule PAK inhibitors suppress MPNST growth and dissemination. The selective group I PAK inhibitors (Frax1036 and GST-PID) tested in this study target all three isoforms and exhibit moderate effects on MPNST cell viability as single agents. We have now used an RNAi approach to knock down individual group I PAK isoforms and their combinations to show that PAK1 and PAK3 knockdown inhibits MPNST cell proliferation, while PAK2 knockdown does not impede the growth of most MPNST cell lines, and in some cases, augments it. Interestingly, combined depletion of PAK1/2/3 has less profound cytotoxic effects compared to single knockdowns of PAK1 or PAK3, suggesting the potential need for isoform-selective PAK inhibitors as therapeutic agents for MPNSTs.

Citation Format: Galina Semenova, Dina Stepanova, Sofiia Karchugina, Cara Dubyk, Sergey Deyev, Alexander Lazar, Jonathan Chernoff. Unique roles of group I PAK isoforms in regulating MPNST cell viability [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B066.
Abstract B088: Identification of a novel regulator in GIST tumorigenesis
Authors: Yun Seongju , Kim Won Kyu , Kim Hoguen
Published: August 2018

Purpose: Gain-of-function mutations of KIT are pathognomonic in the majority of sporadic gastrointestinal stromal tumors (GISTs). Several micro-RNAs have been shown to be dysregulated in GISTs and impact KIT expression levels. Little is known, though, about KIT-independent targets of KIT-regulating mRNAs. We sought to investigate how miR-494 inhibits GIST proliferation and to identify novel target gene. Experimental Design: We used gene expression analyses to identify pathways and target genes affected by miR-494. The expressional relationship between Survivin and miR-494 was determined in 35 GIST tissues. Cell proliferation assay, FACS analysis, colony formation assay, and promoter assays were performed to clarify the roles of Survivin in GIST progression. Results: Gene expression microarray analysis revealed that miR-494 inhibited GISTs by affecting multiple genes in the cell cycle pathway. Survivin was a key target gene of miR-494. Analysis of the 35 GISTs revealed that there was an inverse correlation between Survivin and miR-494 expression (Pearson’s correlation coefficient, r = -0.418, P = 0.012). Downregulation of Survivin inhibited proliferation and colony formation, and resulted in cell cycle alteration. Induced Survivin overexpression relieved miR-494 mediated inhibition of GIST progression. Targeting PI3K effectively suppressed proliferation of GISTs with downregulation of Survivin. Survivin regulated KIT expression at the transcription level. Immunohistochemical analysis using 113 GIST tissues revealed that Survivin expression was significantly correlated with overall survival of GIST patients (P = 0.004). Conclusion: Our findings indicated that miR-494 synergistically suppressed GISTs by concomitantly targeting Survivin and KIT, with accompanying vertical blockade of the PI3K pathways.

Citation Format: Seongju Yun, Won Kyu Kim, Hoguen Kim. Identification of a novel regulator in GIST tumorigenesis [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B088.
Abstract B110: Brusatol-induced degradation of HIF-1α by inhibiting c-Myc causes colorectal cancer cell death under hypoxia
Authors: Oh Eun-Taex , Kim Chan Woo , Kim Ha Gyeong , Park Heon Joo
Published: August 2018

Hypoxia-inducible factor-1 (HIF-1) regulates the expression of ~100 genes involved in metastasis, tumor growth, angiogenesis, chemoresistance, and radioresistance. Therefore, there is growing interest in targeting HIF-1 for cancer treatment. Here, we investigated the molecular mechanisms underlying brusatol-induced degradation of HIF-1α and colorectal cancer cell death under hypoxia. Brusatol pretreatment enhanced degradation of HIF-1α and increased colorectal cancer cell death under hypoxia. Brusatol activated the prolyl hydroxylases (PHDs), and siRNA-mediated knockdown of PHDs prevented brusatol-induced degradation of HIF-1α and colorectal cancer cell death. Additionally, 2,2’-bypyridyl, a ferrous iron chelator, effectively inhibited brusatol-induced degradation of HIF-1α and colorectal cancer cell death in hypoxia by inhibiting PHD activation. We also found that brusatol inhibited c-Myc expression, and showed that overexpression of c-Myc prevented brusatol-induced degradation of HIF-1α and colorectal cancer cell death by inhibiting mitochondrial ROS generation and subsequent ROS-mediated transition of ferrous iron to ferric iron. Consistent with these results, treatment of tumor-bearing mice with brusatol significantly suppressed tumor growth by promoting PHD-mediated HIF-1α degradation. Collectively, our results suggest that brusatol-mediated inhibition of c-Myc/ROS signaling pathway increases HIF-1α degradation by promoting PHD activity and induces colorectal cancer cell death under hypoxia.

Citation Format: Eun-Taex Oh, Chan Woo Kim, Ha Gyeong Kim, Heon Joo Park. Brusatol-induced degradation of HIF-1α by inhibiting c-Myc causes colorectal cancer cell death under hypoxia [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B110.
Abstract B117: Phase II study of brentuximab vedotin and bevacizumab in GCT
Authors: Gupta Shilpa , Maughan Benjamin L.
Published: August 2018

Background: Outcomes in refractory germ cell tumors (GCT) after failure of platinum-based chemotherapy are poor with complete responses with salvage chemotherapy being rare and short-lived. Patients progressing after ≥2 lines of chemotherapy have a dismal prognosis and die from disease. Novel therapies and combination strategies are urgently needed. Cluster of Differentiation antigen-30 (CD30) is expressed in embryonal carcinoma, implicating CD-30 as a target in CD-30+ GCT. Brentuximab vedontin (BV) is an antibody-drug conjugate that combines mono-methyl auristatin E (MMAE) with a CD-30 specific monoclonal antibody, and has shown promising activity in CD30+ GCT. VEGF is involved in tumor development, angiogenesis, and metastasis in GCT, and anti-VEGF monoclonal antibody, bevacizumab, has shown activity in GCT. BV and bevacizumab may be synergistic in refractory CD30+ GCT with no potentially overlapping toxicities. Methods: This is a multicenter phase II study of BV and bevacizumab for the treatment of refractory CD-30+ GCT after disease progression on imaging and/or tumor marker progression with serially rising AFP or bHCG. Patients must have received ≥ 2 lines of platinum-based chemotherapy, but only 1 prior line will be allowed if the patient is ineligible or refuses further platinum-based chemotherapy. For primary mediastinal GCT, failure of 1st-line chemotherapy is allowed. Expression of CD-30 (1% or more) in archival or fresh biopsy is required for eligibility. Primary objective is objective response rate. Secondary objectives are safety and tolerability, PFS, and OS. Exploratory objectives include correlation of clinical outcomes with CD-30 expression in tumors and blood and VEGF level in blood, and presence of circulating tumor cells (CTCs) and correlation with clinical outcomes. BV and bevacizumab will be given every 21 days at doses of 1.8 mg/kg and 15mg/kg, respectively, until disease progression or unacceptable toxicity; intrapatient dose reduction of BV to 1.2 mg/kg will be allowed. A total of 21 patients will be enrolled and results from this study will provide an insight into the safety and efficacy of this combination in refractory CD-30+ GCT. (NCT02988843)

Citation Format: Shilpa Gupta, Benjamin L. Maughan. Phase II study of brentuximab vedotin and bevacizumab in GCT [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B117.
Abstract B118: Potentiation of IL-2’s antitumor efficacy without compromised tolerability by a novel human antibody
Authors: Johnson Kirk , Li Ou , Liu Xiaohe , Beviglia Lucia
Published: August 2018

IL-2 was the first approved cancer immunotherapy and is still recognized for its durable responses. While IL-2 does mobilize relevant antitumor immune cells such as CD8+ T effector and activated NK cells, its utility is limited by parallel expansion of Treg cells and by dose-limiting toxicities. IL-2 Receptor alpha chain binding by IL-2 may be important in driving Treg expansion and some adverse side effects. Over the last decade, there have been approaches at modifying IL-2 structure-function or selecting antibodies that bind IL-2 and bias its activation of preferential cell types. One candidate (pegylated IL-2, NKTR-214) has moved into clinical development. XOMA mAb19 is a fully human monoclonal antibody to IL-2 that selectively compromises binding to IL-2R alpha chains, but not beta-gamma chains, thus potentially expanding IL-2’s antitumor therapeutic index. mAb19 binding characteristics and efficacy in a mouse Lewis Lung Carcinoma model were described at SITC 2016. In the current studies, a CT26 mouse colon carcinoma model was utilized to assess antitumor efficacy and tolerability of combined mAb19 + low-dose IL-2 dosing and to compare such with standard high-dose IL-2 regimens. The CT26 study results presented here demonstrate that mAb19 and IL-2 coadministration potentiates IL-2’s antitumor activity, expands CD8+ T effector and activated NK cells but not Treg cells, and is well tolerated. Specifically, treatment of tumor-bearing mice with about 1 mg/kg mAb19 plus about 0.1 mg/kg IL-2 yielded significant antitumor efficacy, which was at least as substantial as high-dose (e.g. 5 mg/kg) IL-2 regimens wherein significant body weight loss and ~10% mortality were observed. Notably, the mAb19 + IL-2 regimen had no dose-limiting toxicity. Moreover, the magnitude of antitumor response of the combination mAb19+IL2 was superior to that reported for NKTR-214 in the same model (AACR 2015). Preclinical development continues, including assessment for enhanced efficacy with checkpoint inhibitor(s).

Citation Format: Kirk Johnson, Ou Li, Xiaohe Liu, Lucia Beviglia. Potentiation of IL-2’s antitumor efficacy without compromised tolerability by a novel human antibody [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B118.
Abstract B146: A novel TNIK inhibitor potently downregulates cancer stem cell population through attenuation of Wnt signaling
Authors: Uno Yuko , Moriyama Hideki , Kashimoto Shigeki , Masuda Mari , Sawa Masaaki , Yamada Tesshi
Published: August 2018

Background: TNIK (Traf2- and Nck-interacting kinase) has been identified as a component of the β-catenin and T-cell factor 4 (TCF4) complex that regulates the downstream of Wnt signaling. Recent studies indicated that the Wnt pathway is highly activated in cancer stem cells (CSCs), which have been recognized as the driving force of tumorigenesis and mediating tumor recurrence. Thus, eradicating CSCs by inhibiting Wnt signaling may become a new therapeutic option for a complete cure of cancers. Recently we have demonstrated that TNIK is required for the tumor-initiating function of colorectal CSCs, and therefore TNIK is considered to be attractive targets for drug discovery. We have discovered a thiazole-based TNIK inhibitor having potent inhibitory activity for the Wnt signaling. Further optimization of the thiazole-based TNIK inhibitor resulted in an orally available novel TNIK inhibitor, NC-1. In this study, we evaluated in vivo efficacy of the TNIK inhibitor in mouse models as well as its effects on CSCs in vitro. Materials and Methods: To evaluate the effects of NC-1 on the CSCs in SW620, human colon cancer cells, the enzymatic activity of aldehyde dehydrogenase (ALDH) was analyzed by flow cytometry using an Aldefluor assay. The expression of CSCs surface marker protein, CD133, was analyzed using flow cytometry. Antitumor efficacy of NC-1 was evaluated in a human colorectal tumor xenograft mouse model. Results: We demonstrated that treatment of cancer cells with NC-1 significantly downregulated ALDH positive cell population in a dose-dependent manner. In addition, NC-1 suppressed cell surface expression of CD133 in a dose-dependent manner, suggesting that NC-1 preferentially killed CSCs population in vitro. Furthermore, NC-1 inhibited tumor growth in the HCT116 xenograft mouse model.

Citation Format: Yuko Uno, Hideki Moriyama, Shigeki Kashimoto, Mari Masuda, Masaaki Sawa, Tesshi Yamada. A novel TNIK inhibitor potently downregulates cancer stem cell population through attenuation of Wnt signaling [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B146.
Abstract B178: Targeting Myc in triple-negative breast cancer models through the dual inhibition of PIM kinases and CDK9
Authors: Haws Hillary , Kim Wontak , Siddiqui-Jain Adam , Bearss David J. , Warner Steven L. , Whatcott Clifford J.
Published: August 2018

Of the more than 240,000 estimated new cases of breast cancer in 2016 (US), triple-negative breast cancer (TNBC) was expected to comprise roughly 12%. So named because of their lack of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 expression, TNBCs pose a unique therapeutic challenge, with only chemotherapeutic options currently available. New therapeutic options are desperately needed for patients with TNBC. Recent reports have identified a cellular addiction of TNBCs to PIM1, suggesting that the addiction is mediated by PIM regulation of Myc and BH3 proteins MCL-1 or BCL-2. The PIM family of serine/threonine kinases are highly conserved and the link between PIM and Myc function has been well studied. The second-generation PIM inhibitor, TP-3654, has been shown to suppress Myc expression in vitro. Additionally, CDK9 inhibitors are also known to suppress Myc expression. CDK9 inhibition mediates specific reductions in transcription of short-lived mRNAs such as Myc and MCL-1. The CDK9/cyclin T complex is a critical component of the P-TEFb complex, promoting productive RNA elongation through phosphorylation of serine 2 of the heptapeptide repeats of the C-terminal domain of RNA Polymerase II (RNAPII-CTD). We are developing a potent CDK9 inhibitor, alvocidib, and an oral prodrug form of alvocidib named TP-1287, and are investigating the potential clinical utility of CDK9 inhibition in acute myeloid leukemia (AML). We hypothesized that PIM and CDK9 inhibition would be an active combination in models of TNBC due to the added effect of targeting Myc through two independent mechanisms. In the TNBC cell line, MDA-MB-231, TP-3654 reduced relative Myc protein expression by 74%, while alvocidib reduced expression by 71%. The combination of TP-3654 and alvocidib reduced detectable expression 100%, as measured by standard immunoblotting, at concentrations of 100 nM with a 3-hour treatment. To test this hypothesis in vivo, TP-3654 and TP-1287 were tested in the MDA-MB-231 xenograft. Single-agent TP-3654 (150 mg/kg) reduced tumor growth (%TGI) 40.7%, while TP-1287 (3.75 mg/kg) reduced tumor growth 11.6%. The combined-treatment regimen reduced tumor growth by 58.3% at day 18 of treatment. These results support a rationale for further clinical investigation of PIM and CDK9 inhibitors for the suppression of Myc in patients with TNBC.

Citation Format: Hillary Haws, Wontak Kim, Adam Siddiqui-Jain, David J. Bearss, Steven L. Warner, Clifford J. Whatcott. Targeting Myc in triple-negative breast cancer models through the dual inhibition of PIM kinases and CDK9 [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B178.
Abstract B188: DNA topoisomerase-mediated transcription-replication conflicts cause DNA damage by a transient increase of R loops and proteasome activity
Authors: Marinello Jessica , Delcuratolo Maria , Pommier Yves , Binaschi Monica , Pellacani Andrea , Capranico Giovanni
Published: August 2018

DNA topoisomerases have an important function in preventing replication/transcription (R/T) conflicts caused by RNA polymerases elongating in the opposite (or same) direction of advancing replication fork. Published data demonstrated that such persistent R/T conflicts can be rescued by overexpression of RNase H1, which specifically degrades the RNA of DNA:RNA hybrids present in R-loop structures. R loops are a common non-B DNA structure of cellular genomes that mainly occur during transcription. R loops can lead to genome instability; however, they also play a role in important cellular functions. Here, we have determined the dynamics of cellular R loops generated by chemical poisoning of DNA topoisomerases (TOP1 and TOP2) and the role of the proteasome in DNA damage induction by performing detailed kinetics analyses of cellular R loops by immunofluorescence microscopy. Treatment of HeLa and U2OS cells with clinically used topoisomerase inhibitors (camptothecin, LMP-776, MJ-III-65, doxorubicin, sabarubicin) triggers an immediate increase of nucleoplasmic R loops from 2 to 10-20 minutes of treatment, followed by a dramatic reduction of R-loop levels at 1 hour. Concomitantly with the reduction of R-loop structures, DNA damage was detected as phosphorylation of histone H2AX, a marker of DNA double-stranded breaks (DSB). Pretreating cells with MG132 (a proteasome inhibitor) stabilized the presence of R loops at longer treatment times and concomitantly reduced DSB formation, suggesting that the degradation of poisoned topoisomerases is necessary to trigger the pathway resulting in DSB formation. Overexpression of RNaseH1 in U2OS cells abolishes the transient increase of R loops and the induction of DNA damage. Topoisomerase poisoning is able to effectively kill the studied human cancer cells. However, overexpression of RNaseH1 or MG132 markedly reduced cell killing induced by R/T conflicts generated by topoisomerase inhibitors. The results are overall consistent with a necessary function of nuclear proteasome in generating a free DNA break from abortive topoisomerase cleavage complexes that will eventually lead to DSBs.

Citation Format: Jessica Marinello, Maria Delcuratolo, Yves Pommier, Monica Binaschi, Andrea Pellacani, Giovanni Capranico. DNA topoisomerase-mediated transcription-replication conflicts cause DNA damage by a transient increase of R loops and proteasome activity [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B188.
Abstract B195: Immune microenvironment change after acquiring resistance to EGFR TKI therapy in EGFR mutant non-small cell lung cancer
Authors: Kim Tae-Jung , Kang Jin-Hyoung , Hong Sook-hee
Published: August 2018

Introduction: The efficacy of anti-programmed death-1 therapy in EGFR mutant NSCLC is limited. We hypothesized that immune microenvironment was different before and after developing acquired resistance to EGFR-TKI (tyrosine kinase inhibitor) therapy. We evaluated the change of the tumor proportion score (TPS) of programmed death-ligand 1 (PD-L1) and intratumoral CD8+ tumor-infiltrating lymphocyte (TIL) in EGFR mutant NSCLC. Materials and Methods: We identified 44 patients with sufficient paired tumor tissues before and after EGFR-TKI therapy available for analysis. PD-L1 expression on tumor cells was defined by immunohistochemical (IHC) stain with 22C3 pharmDx assay. Intratumoral CD8+ TIL score was also defined by IHC stain. Results: According to paired pre- and post-TKI biopsies comparison, the degree of PD-L1 expression was consistent in both biopsies in 26 (59.1%) patients, but varied upon the development of resistance in 18 (40.9%), with 10 showing higher levels of PD-L1 expression in the resistant biopsy. The score of CD8+ TIL was consistent in both biopsies in 15 (34.1%) patients, but varied upon the development of resistance in 29 (65.9%), with 11 (25%) showing higher levels CD8+ TIL score in the resistant biopsy. Regarding exon 20T790M acquired mutation, only 2 (14.2%) of 14 specimens observed higher TPS of PD-L1 in post-TKI biopsies. We defined high post-TKI TPS of PD-L1 group who observed high TPS of PD-L1 in post-TKI compared to paired pre-TKI biopsies or post- TKI TPS of PD-L1 ≥50%. The post-TKI high TPS of PD-L1 group tended to decrease CD8+ TIL score . 8 observed post-TKI TPS of PD-L1 ≥50% and 7 of 8 observed low CD8+ TIL score. The median progression-free survival of first-generation EGFR-TKI in these 7 patients was statistically significantly lower than the others (6.6 months vs 14.0 months, respectively; P=0.0105). Conclusions: The TPS of PD-L1 and CD8+ TIL score changed after EGFR-TKI therapy. High TPS of PD-L1 and low CD8+ TIL in post-TKI EGFR mutant NSCLC could be related to EGFR-TKI resistance. Before considering anti-PD-1 therapy, reevaluation of PD-L1 should be considered.

Citation Format: Tae-Jung Kim, Jin-Hyoung Kang, Sook-hee Hong. Immune microenvironment change after acquiring resistance to EGFR TKI therapy in EGFR mutant non-small cell lung cancer [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr B195.
Abstract CN05-03: Precision therapeutics with DNA-damaging agents
Authors: Pommier Yves G. , Reinhold William C. , Murai Junko , Thomas Anish
Published: August 2018

Precision therapeutics can be defined as the ability to prescribe effective (curative) therapies only to those patients who will respond, while limiting toxicity to normal tissues and minimizing side effects. The paradigm for precision therapeutics is the BCR-ABL inhibitor imatinib (Gleevec) approved in 2001 for the treatment of Philadelphia chromosome-positive chronic myelogenous leukemia (CML). As DNA-damaging agents have been approved before the era of precision medicine, their use remains empirical. Some patients respond remarkably well while others only suffer from the drug side effects. The possibility of using DNA-damaging agents in the context of precision medicine changed with the approval of the poly(ADPribose) polymerase (PARP) inhibitors, which have been approved for patients with BRCA deficiencies and prior response to platinum drugs, and act as DNA-damaging agents by trapping PARP1 and PARP2 on DNA lesions. We will review the use of cancer cell line genomics to discover novel determinants of response to DNA-targeted agents, and to elaborate molecular signatures of response. We will also discuss the broad implications of the discovery of Schlafen 11 (SLFN11) as a novel determinant of response to PARP inhibitors, platinum derivatives, topoisomerase inhibitors, gemcitabine, hydroxyurea, and cytosine arabinoside. We will demonstrate the use of our novel crossdatabase (cdb) web-based tools to mine genomics and pharmacologic determinants of response and genomic signatures for anticancer drugs (https://discover.nci.nih.gov/cellminercdb).

Citation Format: Yves G. Pommier, William C. Reinhold, Junko Murai, Anish Thomas. Precision therapeutics with DNA-damaging agents [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr CN05-03.