bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract B078: MiXenoTM: a fast and efficient humanized tumor model system for in vivo efficacy evaluation of novel immunotherapeutics
Authors: Zhang Lan , Zhang Juan , Qiao Meng , Yan Xuefei , Ding Jian , Chen Fei , An Xiaoyu , Tan Weibin , Fu Xiaoyan , Yang WenQing , Shi Qian
Published: August 2018

Recently approved cancer immunotherapy drugs have been shown to not only suppress tumor growth but also prolong survival of patients with various tumor types. More and more relevant and sophisticated preclinical tumor models are required by the I/O drug discovery industry. Different strategies of humanized mouse model systems have been published, including human hematopoietic stem cell (HSC) humanized and human PBMC reconstituted tumor models; each has advantages and disadvantages. Compared with HSC humanization, using human PBMC cells to reconstitute human immune system demonstrated fast engraftment and less variable results. CrownBio has successfully established a platform, known as MiXenoTM,that uses PBMC-humanized xenograft models to evaluate the in vivo antitumor activity of immunotherapeutics of human origin. The platform has proven to be a valuable tool and is being widely used by our collaborators. The current study is designed to address model optimization and application aspects of the MiXeno platform, including PBMC donor to donor variation, feasibility of in vitro PBMC donor screening, and selection of suitable models for different targets. More than a dozen MiXeno tumor models have been established and validated where human immune cells were reconstituted in the mouse system for evaluation of human-origin bispecific antibodies, immune checkpoint inhibitors, or immune modulators. These MiXeno models were characterized with regards to reconstitution of T cells, tumor response to anti-PD-1 and anti-CTLA4 antibodies, and onset of possible graft-versus-host disease (GVHD) or graft-versus-tumor response (GVT). Evaluation of expanded immune-oncology therapeutics is in progress, including NK and dendritic cells-targeted immune-modulating drugs.

Citation Format: Lan Zhang, Juan Zhang, Meng Qiao, Xuefei Yan, Jian Ding, Fei Chen, Xiaoyu An, Weibin Tan, Xiaoyan Fu, WenQing Yang, Qian Shi. MiXenoTM: a fast and efficient humanized tumor model system for in vivo efficacy evaluation of novel immunotherapeutics [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 B078.
Abstract B087: A systematic approach to JAK/STAT pathway shut-down
Authors: Montazeri Aliabadi Hamidreza , Bousoik Emira , Mahdipoor Parvin
Published: August 2018

Janus Kinase Protein (JAK) plays a crucial role in a variety of intracellular mechanisms, and has been extensively studied for its role in proliferation and survival of cancer cells. One of the unique characteristics of this kinase is the variety of cell membrane receptors with which it is associated, and can trigger JAK activation process. Family of Signal Transducer and Activators of Transcription (STATs) are the direct downstream proteins that further transfer JAK signaling to the nucleus, which results in modification of expression level of a wide range of proteins. Triple-negative breast cancer (TNBC) represents one of the most aggressive and challenging subtypes of human breast cancer, due to lack of estrogen, progesterone, and human epidermal growth factor receptor 2 (HER2) receptors, which renders the cells nonresponsive to hormone therapy. Several studies have confirmed that IL-6/gp130/JAK2/STAT3 signaling pathway is one of the crucial pathways that is implicated in TNBC development. However, monotherapies targeting JAK2 or STAT3 with molecularly targeted drugs have faced several challenges, including inherent and acquired resistance. Therefore, we aimed to determine feasibility and efficacy of therapy of TNBC using combinatorial silencing of different components in gp130/JAK2/STAT3 pathway. The downregulatory effects of siRNA targeting gp130, JAK2, STAT3, Importin α-3 alone or in combination were evaluated in human TNBC cells MDA 231 and MDA 468, and their effect on downstream targets involved in cell apoptosis and cell cycle were determined by real-time PCR and Western blot. The effect of individual and combinatorial silencing of the pathway components on cell proliferation and cell migration were also examined using CCK assay and Scratch assay, respectively. The siRNA treatment effectively reduced gene expression of gp130/JAK2/STAT pathway components at the mRNA level. Simultaneous inhibition of selected components significantly decreased TNBC cell proliferation rate. Moreover, combinatorial siRNA silencing inhibited the migration of TNBC cells. In conclusion, simultaneous inhibition of well-selected components of JAK/STAT pathway could represent an effective therapy for human TNBC. This warrants further in vivo study in animal models.

Citation Format: Hamidreza Montazeri Aliabadi, Emira Bousoik, Parvin Mahdipoor. A systematic approach to JAK/STAT pathway shut-down [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 B087.
Abstract B112: Development and preclinical evaluation of a novel BET inhibitor FF-1027T
Authors: Makita Keiko , Saeki Kazunori , Tanaka Tadashi , Kawanishi Yasutomo , Kimura Toshifumi , Watanabe Shinichi , Kakinuma Chihaya , Hagiwara Shinji , Shimada Yasuhiro
Published: August 2018

Bromodomain and extra-terminal (BET) family of proteins regulate gene expression by binding acetylated-lysine residue in histone at the gene promoter and enhancer elements through the two bromodomains (BD1 and BD2). Subsequently, they activate transcriptional elongation at the binding sites. Small-molecule compounds inhibiting the interaction between BET proteins and acetylate-lysine in histone have been expected as a promising strategy for cancer therapy. They can show pharmacologic action by regulating the transcription of MYC and other cancer-associated genes. We identified a novel BET inhibitor, FF-1027T, that is structurally different from the (+)JQ-1 class BET inhibitors such as OTX015. FF-1027T is more soluble in aqueous solution than known BET inhibitors, which offers an advantage in the application of drug formulations. Through the TR-FRET assay, FF-1027T exhibited binding to BRD2/3/4 with a preference for BD1 over BD2. FF-1027T showed antiproliferative activity in vitro across broad cancer cell lines derived from hematologic malignancies or solid tumors. In accordance with the previous report about BET inhibitors, FF-1027T displayed higher antiproliferative activity to hematologic malignancies than solid tumor-derived cell lines with less than 100 nM GI50 values (12 out of 21 cells lines). In particular, FF-1027T showed anti-proliferative activities against cell lines derived from solid tumors, such as colon, lung, breast, and prostate cancer, with less than 300 nM GI50 values in almost 30% of the cell lines. In AML xenograft tumor models, oral or intravenous administration of FF-1027T resulted in almost complete reduction of tumor growth. Intravenous treatment was achieved by high solubility in an aqueous solution of FF-1027T. Our present results suggested that gastrointestinal tract (GI) damage through topical effects of BET inhibitors on the mucosal surface can be avoided by intravenous administration. These results demonstrated that FF-1027T is a potent BET inhibitor and supports the clinical further development of FF-1027T in hematologic malignancies and solid tumors.

Citation Format: Keiko Makita, Kazunori Saeki, Tadashi Tanaka, Yasutomo Kawanishi, Toshifumi Kimura, Shinichi Watanabe, Chihaya Kakinuma, Shinji Hagiwara, Yasuhiro Shimada. Development and preclinical evaluation of a novel BET inhibitor FF-1027T [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 B112.
Abstract B113: Development of a novel synthetic consensus DNA vaccine that targets multiple MAGE-A family members for anticancer immune therapy
Authors: Duperret Elizabeth K. , Trautz Aspen , Paik Megan , Reed Charles , Yan Jian , Weiner David B.
Published: August 2018

Cancer/testis (CT) antigens have emerged as attractive targets for cancer immune therapy due to their overexpression in tumor tissues and lack of expression in normal tissues. In particular, several clinical studies have been initiated to target the MAGE-A family of CT antigens for melanoma. These have included recombinant protein immunization and TCR-based gene therapy for MAGE-A3. The recombinant protein immunizations resulted in poor CD8+ T-cell responses and lack of efficacy thus far in the clinic. TCR-based gene therapy induced robust immune responses but unexpected toxicity. There is therefore a need to develop safe and effective therapies targeting the MAGE-A family of proteins for cancer therapy. In this study we performed a thorough analysis of MAGE-A RNA expression in The Cancer Genome Atlas (TCGA) and demonstrated that a high proportion of patients, in particular patients with melanoma and lung squamous cell carcinoma, exhibit expression of multiple MAGE-A family members simultaneously within the same tumor sample. Based on this information, we designed a consensus MAGE-A DNA vaccine that retains high homology (>85%) to multiple MAGE-A isoforms. Because mice and human MAGE-A family members are poorly conserved, we designed separate consensus constructs for testing in mice and in primates. Upon delivery of this mouse consensus MAGE-A vaccine intramuscularly followed by electroporation (EP) in C57Bl/6 mice, we detected robust IFN-γ and TNF-α CD8+ T-cell responses against multiple MAGE-A isoforms, including MAGE-A1, MAGE-A2, MAGE-A3, MAGE-A5, MAGE-A6, and MAGE-A8 (p<0.005). Furthermore, we detected robust cytotoxic CD107a/IFN-γ/T-bet triple-positive CD8+ T cells in mice immunized with the consensus mouse MAGE-A vaccine. We evaluated the potency and cross-reactivity of this consensus mouse MAGE-A DNA vaccine in genetically diverse, outbred mice. We found that the majority of these mice (14/15) were capable of mounting a cross-reactive immune response and breaking tolerance to multiple MAGE-A isoforms simultaneously. We also demonstrated that this consensus mouse MAGE-A DNA vaccine is capable of slowing tumor growth in a therapeutic tumor challenge using the YUMM1.7 melanoma tumor model and the TC-1 lung tumor model. These results support the use of optimized MAGE-A consensus vaccines for cancer immune therapy.

Citation Format: Elizabeth K. Duperret, Aspen Trautz, Megan Paik, Charles Reed, Jian Yan, David B. Weiner. Development of a novel synthetic consensus DNA vaccine that targets multiple MAGE-A family members for anticancer immune therapy [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 B113.
Abstract B122: 3,3′-bis(2-aminoethanol)-2,2′-binaphthoquinone promotes killing of acute myeloid leukemia cells by augmenting oxidative stress and inhibiting indoleamine dioxygenase
Authors: Chang Elizabeth Tsuying , Carter-Cooper Brandon A. , Dash Smaraki , Ferraris Dana , Emadi Ashkan , Lapidus Rena G.
Published: August 2018

Introduction: Acute myeloid leukemia (AML) is a genetically heterogeneous neoplasm with poor clinical outcome after treatment with current conventional chemotherapy. New treatments are therefore needed to combat this aggressive cancer. One of the hallmarks of AML blasts is disrupted cellular oxidative state resulting from elevated level of reactive oxygen species (ROS) and overexpressed antioxidant proteins. Another characteristic of AML blasts is escaping host immune surveillance mediated in part by overexpression of the tryptophan-metabolizing enzyme, indoleamine 2,3-dioxygenase (IDO). We have designed and synthesized a novel hydroxylamine dimeric naphthoquinone (MCD-66), which can kill leukemia cells by dual mechanisms: 1) negatively perturbing cellular oxidative balance, and 2) effectively inhibiting IDO-1. Results: Two AML cell lines (MV4-11 and MOLM14) were treated with increasing doses of the clinically used naphthoquinones, atovaquone, and vitamin K, as well as with MCD-66, and IC50 curves were generated. With nanomolar range IC50s, MCD-66 was 25-30 fold more potent than other naphthoquinones against AML cells. MCD-66 effectively inhibited clonogenicity of AML cells in a dose-dependent manner. When MV4-11 cells were treated with MCD-66 at IC50 concentration, ROS levels significantly peaked after 2 hours and returned to baseline within 24 hours. The augmented production of ROS led to concomitant increase in DNA damage, evidenced by γH2AX foci in treated AML blasts. Additionally, MCD-66 inhibited IDO-1 activity at 1 µM (37%) and 10 µM (79%), but not its isozymes IDO-2 or tryptophan-2,3-dioxygenase (TDO). Conclusion: The novel amino-alcohol dimeric naphthoquinone MCD-66 has shown promising activity against AML blast in vitro with dual mechanisms of action. The in vivo studies focusing on tolerability and efficacy, including modulating immune surveillance in xenograft models of AML, are ongoing.

Citation Format: Elizabeth Tsuying Chang, Brandon A. Carter-Cooper, Smaraki Dash, Dana Ferraris, Ashkan Emadi, Rena G. Lapidus. 3,3′-bis(2-aminoethanol)-2,2′-binaphthoquinone promotes killing of acute myeloid leukemia cells by augmenting oxidative stress and inhibiting indoleamine dioxygenase [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 B122.
Abstract B133: Identification of elatol as a novel eIF4A inhibitor and stress response activator
Authors: Peters Tara L. , Tillotson Joseph , Li Lingxiao , Chapman Eli , Schatz Jonathan H.
Published: August 2018

It is well established that protein translation can contribute the most adaptable regulation of protein-coding gene expression, is frequently hijacked during oncogenesis, and can be targeted therapeutically. Most regulation of protein translation occurs at the initiation step with formation and function of the eIF4F complex. Many different avenues, both direct and indirect, have been explored to inhibit eIF4F and thus protein translation initiation, in particular drugs targeting eIF4F’s core-enzymatic subunit, the DEAD-box RNA helicase eIF4A. Despite extensive preclinical evaluation and high antitumor activity of these compounds, none has progressed to evaluation in cancer patients, due to a variety of pharmacokinetic and pharmacodynamic issues. We designed a novel screen to identify eIF4A inhibitors by measuring ATP hydrolysis and screened a collection of ~1,200 natural compounds and purified extracts. The marine natural product elatol was the top hit in our screen, that not only showed selectivity for eIF4A over other dead box family helicases and a panel of 97 common kinases, but also induced apoptosis in a broad range of cancer cell lines from the NCI-60 cancer cell line and CCLE panels. Elatol is well tolerated in mice at a single dose of up to 65mg/kg and showed antitumor activity. Elatol treatment reduced global protein translation measured through polysome profiling and O-propargyl puromycin incorporation as well as cap-dependent translation measured by luciferase reporter and Western blotting. The effects of elatol are similar to the rocaglate silvestrol, which inhibits eIF4A although through a very different mechanism, but elatol requires higher concentrations to achieve these effects. Interestingly, elatol treatment causes strong immediate induction of the stress response transcription factor ATF4, though assessment in ATF4-deficient cells showed the toxicity of elatol is not dependent on ATF4. Unlike with silvestrol treatment, loss of translationally regulated proteins MYC and CYCLIN D3 following elatol treatment can be partially rescued by blocking the eIF2α-mediated stress response with ISRIB. Which eIF2α kinase may be mediating these effects is still under investigation. The novel mechanism of inhibition of ATP hydrolysis may be driving these unique observations compared to other eIF4A inhibitors. We believe this study provides a novel approach for identification of small molecules that have greater clinical promise for eIF4A inhibition.

Citation Format: Tara L. Peters, Joseph Tillotson, Lingxiao Li, Eli Chapman, Jonathan H. Schatz. Identification of elatol as a novel eIF4A inhibitor and stress response activator [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 B133.
Abstract B137: Novel potent salicylic, benzoic, and benzohydroxamic acid-based small-molecule STAT3 inhibitors induce antitumor effects in breast cancer xenografts
Authors: Yue Peibin , Lopez-Tapia Francisco , Brotherton-Pleiss Christine , Tius Marcus , Turkson James
Published: August 2018

We investigated the molecular determinants for the activity of the previously reported salicylic BP-1-102 (IC50 6.8 ± 2.5 μM), benzoic SH4-54 (IC50 4.4 ± 0.3 μM), and benzohydroxamic acid SH5-07 (IC50 3.9 ± 0.6 μM) small-molecule STAT3 inhibitors in order to derive structurally optimum analogs with improved potency and pharmacokinetic parameters. All three leads are based on N-methylglycinamide scaffold, with its two amine groups condensed with three different functionalities. The three functionalities were separately modified to generate various series of new analogs. The inhibitory activities of the new analogs against STAT3 DNA-binding in vitro were determined by electrophoretic motility shift assay. Some new analogs show dramatically improved potency compared to the corresponding lead compounds. Notably, analogs H098, H127, H142, H145, H152, and H155 showed more than 10-fold improved potency in inhibiting STAT3 DNA-binding activity in vitro, with IC50 of 300 - 600 nM. Using analogs H105 and H120, we show that the new analogs decreased STAT3 DNA-binding activity and phosphorylation at Tyr705 in MDA-MB-231 and MDA-MB-468 cells, two human triple-negative breast cancer lines harboring constitutively active STAT3, within as early as 30 min. Furthermore, the new analogs potently inhibited the growth and viability of the human cancer cells with persistently active STAT3, with IC50 of 1.2 - 2.0 µM. The potent analogs specifically disrupted STAT3 DNA-binding activity in vitro over that of STAT1 and STAT5, and they further showed minimum inhibitory effect on the proliferation of human cancer cells that do not harbor persistently active STAT3. Initial in vivo efficacy study in nude mouse model showed that oral administration of H105 and H120 suppressed the growth of tumor xenografts generated from human breast cancer line harboring constitutively active STAT3. Thus, we have made substantial progress and broken the nanomolar barrier in developing STAT3 inhibitors, and these compounds are the first nanomolar STAT3 inhibitors reported to date that are direct disruptors of STAT3 activation, which show in vivo activity.

Citation Format: Peibin Yue, Francisco Lopez-Tapia, Christine Brotherton-Pleiss, Marcus Tius, James Turkson. Novel potent salicylic, benzoic, and benzohydroxamic acid-based small-molecule STAT3 inhibitors induce antitumor effects in breast cancer xenografts [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 B137.
Abstract B142: The anticancer agent Dp44mT upregulates the AMPK-dependent energy homeostasis pathway in cancer cells
Authors: Krishan Sukriti , Sahni Sumit , Richardson Des R.
Published: August 2018

Background: Iron plays a crucial role in cellular energy transducing pathways and tumor cell proliferation. Therefore, metals (such as iron) could play an important role in the regulation of the AMPK-dependent pathway regulating cellular energy homeostasis. This investigation examined the effect of the iron and copper chelator and potent anticancer agent, di-2-pyridylketone 4,4-dimethyl-3-thiosemicarbazone (Dp44mT), on AMPK-mediated energy homeostasis. Methods and Results: These studies demonstrated that Dp44mT, which forms intracellular redox-active complexes with iron and copper, significantly activated AMPK (i.e., p-AMPK/AMPK ratio) in 5 different tumor cell-types. Furthermore, examination of the Dp44mT-metal complexes demonstrated that the effect of Dp44mT on AMPK was due to a dual mechanism: (1) its ability to chelate metal ion; and (2) the generation of reactive oxygen species (ROS). The activation of the AMPK pathway by Dp44mT was mediated by the upstream kinase, liver kinase B1 (LKB1), which is a known tumor suppressor. Moreover, using AMPKα1-selective silencing, we demonstrated that Dp44mT activated AMPK, resulting in inhibition of acetyl CoA carboxylase 1 (ACC1) and raptor, and activation of Unc-51 like kinase (ULK1). Conclusions: These effects are vital for inhibition of fatty acid synthesis, suppression of protein synthesis, and autophagic activation, respectively. Together, this AMPK-mediated repair response aims to rescue the loss of metal ions via chelation and the induction of cytotoxic damage mediated by redox cycling of the Dp44mT-metal ion complex. In conclusion, this study demonstrates for the first time that chelators target the AMPK-dependent energy homeostasis pathway.

Citation Format: Sukriti Krishan, Sumit Sahni, Des R. Richardson. The anticancer agent Dp44mT upregulates the AMPK-dependent energy homeostasis pathway in cancer 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 B142.
Abstract B147: A phase 1 PK/PD study of ASN003, a novel, highly selective BRAF and PI3K dual inhibitor, in patients with advanced solid tumors
Authors: Rasco Drew , Lakhani Nehal , Sullivan Ryan , Mita Monica , Shah Jaimini , Usansky Helena , Reddy Sanjeeva , Rao Niranjan , Denis Louis J. , Tolcher Anthony , Flaherty Keith
Published: August 2018

Background: RAS-RAF-MEK and PI3K-AKT-mTOR are two major pathways involved in tumor cell signaling and growth. Components of these pathways are frequently mutated in a broad range of tumors. ASN003 is a highly selective and potent (low nM IC50) inhibitor of BRAF and PI3K-α and -δ (low affinity for PI3K-β). ASN003 shows strong antitumor activity in tumor models harboring BRAF and PIK3CA or PTEN mutations, and also in patient-derived xenograft (PDX) models that are resistant to selective BRAF and MEK inhibitors. Patients and Methods: Oral once-daily ASN003 is being evaluated for safety/tolerability and preliminary efficacy in eligible patients with advanced solid tumors using an accelerated dose titration design (Part A) and enrolling cohorts of patients diagnosed with melanoma, CRC, NSCLC, and other solid tumors with a BRAF, PIK3CA, or PTEN mutation at MTD (Part B). Pharmacokinetic (PK) profile and the pharmacodynamic (PD) effects of ASN003 on tumor tissue biomarkers such as pERK and pS6 are investigated in both parts of the study. Results: Patient accrual in Part A is ongoing. As of June 2017, nine eligible patients are enrolled in dose levels ranging from 10 - 240 mg QD. ASN003 has been well tolerated. Treatment-related adverse events (TRAEs) were mild (G1) to moderate (G2). TRAEs include diarrhea (G2) (n=1), nausea/vomiting (G1), blurred vision (G1), and dry mouth/lips/skin (G1). Transient G1 elevation of glucose and insulin c-peptide levels has been noted in 1 pt. No G3/4 or serious TRAEs have been observed to date. The PK profile showed dose-dependent, systemic exposure with Cmax ranging from 74 to 1055 ng/mL, AUCT from 912 to 20100 ng.h/mL. Conclusions: ASN003 is a novel small molecule, with uniquely selective and potent inhibition of BRAF, PI3K-α and -δ kinases. To date, ASN003 was well tolerated at doses up to 240 mg QD and achieved good systemic exposure. Updated and detailed clinical safety/efficacy and PK/PD results will be presented.

Citation Format: Drew Rasco, Nehal Lakhani, Ryan Sullivan, Monica Mita, Jaimini Shah, Helena Usansky, Sanjeeva Reddy, Niranjan Rao, Louis J. Denis, Anthony Tolcher, Keith Flaherty. A phase 1 PK/PD study of ASN003, a novel, highly selective BRAF and PI3K dual inhibitor, in patients with advanced solid tumors [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 B147.
Abstract B153: CDK4/6 inhibitor synergizes with mTOR inhibitor to suppress cholangiocarcinoma pathogenesis
Authors: Song Xinhua , Liu Xianqiong , Wang Jingxiao , Chen Xin
Published: August 2018

Intrahepatic cholangiocarcinoma (ICC) is an aggressive cancer. It lacks effective therapies and is associated with high mortality rate as well as poor prognosis. Our recent study suggests that treatment of pan-mTOR inhibitor MLN0128 leads to stable disease in murine ICC model induced by activated AKT and Yap (AKT/YapS127A) via inducing apoptosis without affecting tumor cell proliferation. Palbociclib is a pan CDK4/6 inhibitor that has been approved by the FDA for the treatment of HR-positive advanced-stage breast cancer. However, its efficacy in ICC has not been investigated. ICC cells are known to be highly proliferative. Here we hypothesize that palbociclib is effective against ICC by inhibiting tumor cell proliferation. Furthermore, it may synergize with MLN0128 to inhibit ICC growth in vivo. We tested the therapeutic efficacy of palbociclib alone or in combination with MLN0128 in human ICC cell lines as well as in AKT/YapS127A ICC model.

We found that in vitro palbociclib inhibits ICC cell growth via inhibiting cell cycle progression. The long-term cell growth, but not the short-term cell survival, to palbociclib is RB-dependent. Concomitant treatment of palbociclib with MLN0128 has a synergistic effect in inhibiting ICC cell viability. In AKT/YapS127A ICC preclinical model, treatment with palbociclib or MLN0128 alone all led to stable disease. In striking contrast, combined treatment of palbociclib with MLN0128 resulted in significant tumor regression. Mechanistically, we found that combined palbociclib with MLN0128 has a profound inhibitory effect in inhibiting ICC cell proliferation both in vivo and in vitro. In summary, our study suggests that palbociclib synergizes with MLN0128 to inhibit ICC cell proliferation, and combined treatment of palbociclib with MLN0128 represents promising novel therapeutics against this deadly malignancy.

Citation Format: Xinhua Song, Xianqiong Liu, Jingxiao Wang, Xin Chen. CDK4/6 inhibitor synergizes with mTOR inhibitor to suppress cholangiocarcinoma pathogenesis [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 B153.
Abstract B184: TPX-0005, a highly potent TRK inhibitor, effectively overcomes clinical-resistance TRK mutations including solvent front mutants TRKA G595R, TRKB G639R, and TRKC G623R
Authors: Cui J. Jean , Zhai Dayong , Deng Wei , Rogers Evan , Huang Zhongdong , Whitten Jeffrey , lim John , Li Yishan
Published: August 2018

The tropomyosin receptor kinases (TRKs), including TRKA/B/C encoded by NTRK1/2/3 genes, are high-affinity receptors for neurotrophins. Oncogenic rearrangement of NTRK1, NTRK2, and NTRK3 have been identified in many solid malignancies. The use of TRK inhibitors entrectinib and larotrectinib has led to clinical benefit in patients with solid malignancies harboring oncogenic NTRK fusions. Similar to ALK and ROS1 inhibitor treatment, the solvent front mutations TRKA G595R and TRKC G623R (both analog to ALK G1202R) were reported in clinic from treatment-resistant patients. A new generation of TRK inhibitors targeting both wild type and mutated TRKs is highly needed for effectively treating patients harboring fusion TRKs. TPX-0005, a novel three-dimensional macrocycle with a much smaller size than current TRK inhibitors in the clinic, was designed to overcome clinical resistance mutations systematically. TPX-0005 potently inhibited both wild type and mutant TRKs including solvent front mutations. TPX-0005 showed pico-molar activity against TRK kinases (IC50s 0.83 nM, 0.05 nM, and 0.10 nM for TRKA/B/C, respectively) in Reaction Biology kinase assay. TPX-0005 is the most potent TRK inhibitor in clinic and effectively overcomes clinical resistance TRK mutations as shown in the table in cell proliferation assays. It was recently reported that LOXO-195 inhibited the phosphorylation of TRKA and ERK kinases in NIH3T3 cell line expressing ΔTRKA G595R or ETV6-TRKC G623R with IC50s of 7 nM and 45.5 nM, respectively. TPX-0005 is more than 10-fold more potent than LOXO-195. In the xenograft tumor model studies including human PDX model, TPX-0005 dramatically caused tumor regression in the tumors carrying WT or solvent-front mutated TRK fusion gene. Overall, TPX-0005 demonstrated desired drug-like properties, good safety profile, and is a supreme TRK inhibitor against WT and mutated TRKs. A phase 1/2 clinical trial of TPX-0005 is actively being pursued (NCT03093116). KM-12 IC50 (nM)Ba/F3 Cell Proliferation Assay IC50 (nM)InhibitorTPM3-TRKAWTLMNA-TRKA WTLMNA-TRKA G595RETV6-TRKB WTETV6-TRKB G639RETV6-TRKC WTETV6-TRKC G623RTPX-0005<0.2<0.20.4<0.20.6<0.23Entrectinib9.20.3705<0.513840.61000Larotrectinib12.33.5102410.9300010.21500

Citation Format: J. Jean Cui, Dayong Zhai, Wei Deng, Evan Rogers, Zhongdong Huang, Jeffrey Whitten, John lim, Yishan Li. TPX-0005, a highly potent TRK inhibitor, effectively overcomes clinical-resistance TRK mutations including solvent front mutants TRKA G595R, TRKB G639R, and TRKC G623R [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 B184.
Abstract B193: Characterization of selective active-site targeted covalent inhibitors of usp7
Authors: Wang Feng , Wu Jian , Wang Liqing , Sokirniy Ivan , Wang Hui , Chen Lee , Cunnion Brigid , Sterner David , Grove Charles , Bregnard Thomas , Weinstock Joseph , Mattern Michael , Bezsonova Irina , Hancock Wayne W. , Kumar Suresh
Published: August 2018

The ubiquitin-specific protease 7 (USP7) has emerged as an attractive oncology/immune-oncology target owing to its critical roles in several cancer-related signaling pathways as well as its essential role in maintaining functions of Foxp3+ T-regulatory cells (Tregs), the key players in tumor immune evasion. Progenra has developed a series of compounds that inhibit purified USP7 selectively and attenuate USP7 activity in cells and in vivo; these inhibitors exert antitumor activity directly and also facilitate immune-mediated antitumor activity by suppressing Treg functions. However, the precise mechanism of action of these compounds remains unclear. In this study, using a combination of NMR spectroscopy, mass spectrometry, and single amino-acid substitution approaches, we have now demonstrated that our USP7 inhibitors specifically target the catalytic pocket of USP7 and modify its active site cysteine (Cys223) by forming a covalent adduct. Consistent with the covalent binding mechanism, pharmacokinetic studies revealed long-lasting, irreversible USP7 inhibition after a short pulse treatment with inhibitor, accompanied by changes in the level and ubiquitylation of various pharmacodynamic markers, including the Treg lineage-specific transcription factor Foxp3. Detailed knowledge of the mechanism of USP7 inhibition will permit the rational design of improved inhibitors as a new class of anticancer agent.

Citation Format: Feng Wang, Jian Wu, Liqing Wang, Ivan Sokirniy, Hui Wang, Lee Chen, Brigid Cunnion, David Sterner, Charles Grove, Thomas Bregnard, Joseph Weinstock, Michael Mattern, Irina Bezsonova, Wayne W. Hancock, Suresh Kumar. Characterization of selective active-site targeted covalent inhibitors of usp7 [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 B193.
Abstract B198: Targeting CSK kinase activity to enhance antitumor immunity
Authors: Wang Cindy , Cao Carolyn , Berman-Booty Lisa , Swanson Jesse , Eraslan Rukiye , Sanjuan Miguel , Vite Gregory , Qin Lan-Ying , Hunt John , Fink Brian , Wee Susan
Published: August 2018

To mount an effective immune response, a T-cell receptor (TCR) must first recognize a cognate antigen presented by malignant cells. Successful effector T-cell activation initiates an intracellular signaling cascade that results in the release of cytotoxins and proinflammatory cytokines that ultimately result in the elimination of antigen-presenting diseased cells. A key regulator of this signaling cascade is the C-terminal Src (CSK) kinase. In lymphocytes CSK inhibits T-cell activation by phosphorylating the SRC kinase family member LCK at tyrosine 505 and thereby terminates the signaling cascade. To assess whether relieving an intracellular blockade of TCR signaling will lead to a more robust T-cell response, and hence improved tumor immunity, we developed both genetic and pharmacologic approaches to inhibit CSK activity. A tamoxifen-inducible transgenic CSK knockout mouse was engineered to bypass the embryonic lethality observed with constitutive systemic CSK depletion. As expected, loss of CSK enhanced cytokine production and increased antitumor immune response in the MC38 syngeneic tumor mouse model. Potent and selective CSK small-molecule inhibitors, in the presence of TCR stimulation, similarly activated the proximal TCR signaling pathway and increased cytokine production and proliferation. In an in vivo efficacy study, however, the CSK inhibitor as monotherapy or in combination with aPD1 did not improve antitumor immune response at the dose levels tested. This seemingly discrepant finding in tumor response observed in the tamoxifen-inducible KO mice and mice treated with the CSK inhibitor may reflect the need for a more optimized dosing regimen and target coverage. In this poster, we will present our findings on the role of CSK inhibition in tumor immunity.

Citation Format: Cindy Wang, Carolyn Cao, Lisa Berman-Booty, Jesse Swanson, Rukiye Eraslan, Miguel Sanjuan, Gregory Vite, Lan-Ying Qin, John Hunt, Brian Fink, Susan Wee. Targeting CSK kinase activity to enhance antitumor immunity [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 B198.
Abstract B204: Integrin β1 plays a crucial role in vasculogenic mimicry formation
Authors: Kawahara Ryota , Niwa Yuki , Simizu Siro
Published: August 2018

Tumor metastasis is caused by multiple processes, such as epithelial-mesenchymal transition, lymph node metastasis, and angiogenesis. In recent years, vasculogenic mimicry (VM) is focused on the association with tumor malignancy. VM is a unique phenomenon, a blood vessel-like network structure formed only by cancer cells without vascular endothelial cells, and is observed in extracellular matrix (ECM) rich region. Although previous studies suggested that VM plays a crucial role in tumor metastasis, a detailed mechanism of VM formation has not been fully understood. Latest studies indicate that cell surface proteins such as integrins and cadherins contribute to VM formation. In this study, we focused on transmembrane cell surface receptor, integrin β1. Integrin β1 is an important factor for interactions between cell-cell and cell-ECM, and mediates several cell signalings. Therefore, we investigated the importance of integrin β1 in VM formation. We assessed VM formation capability as network structure formed by cancer cells on matrigel. Since previous studies revealed that Ca2+ regulates integrin activities, we treated with EGTA and CaCl2 to assess whether Ca2+ is necessary for VM formation. We performed integrin β1 gene knockout (KO) by using CRISPR/Cas9 system in human fibrosarcoma HT1080 cells, and assessed VM formation capability of the KO cells. In addition, we established integrin β1-rescued HT1080 cells by reintroduction of Cas9-resistant integrin β1-expressing vector to integrin β1-KO HT1080 cells to confirm the importance of integrin β1 in VM formation. Furthermore, we also established integrin β1-KO human breast cancer MDA-MB-231 cells to verify that integrin β1 is necessary for VM formation in other human cancer cell lines. As a result, chelation of Ca2+ by treatment with EGTA inhibited network formation in HT1080 cells, and cotreatment with CaCl2 rescued this effect, suggesting that integrins might be important for VM formation. In integrin β1-KO HT1080 cells, which is confirmed the completely knockout of integrin β1 by Western blot, network formation was abrogated. Additionally, integrin β1-rescued HT1080 cells exhibited network formation as well as parental HT1080 cells. These results suggested that integrin β1 is a critical factor in VM formation. Furthermore, integrin β1-KO MDA-MB-231 cells also did not form network structure, suggesting that integrin β1 plays a crucial role in VM formation in general human cancer cell lines. Taken together, our study provides new knowledge of the association between VM and integrin β1, and inhibition of integrin β1 may be a novel therapeutic approach for metastatic cancer.

Citation Format: Ryota Kawahara, Yuki Niwa, Siro Simizu. Integrin β1 plays a crucial role in vasculogenic mimicry formation [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 B204.
Abstract B210: BET inhibitors show superior ability to suppress the progression of tumors containing the Pro47Ser single-nucleotide polymorphism of p53
Authors: Barnoud Thibaut , Basu Subhasree , Kung Che-Pei , Reiss Matthew , Zhang Rugang , Murphy Maureen
Published: August 2018

The tumor suppressor TP53 is the most frequently mutated gene in human cancer and serves to restrict both tumor initiation and progression. Single-nucleotide polymorphisms (SNPs) in the p53 pathway can have a marked impact on p53 tumor suppressor function, and several have been associated with increased cancer risk. We have reported that a naturally occurring SNP affects codon 47 of TP53 (rs1800371, G/A). In most individuals, codon 47 encodes a proline (P47). However, approximately 2.5% of African-Americans express a p53 allele with a serine residue (S47) at this position. In order to compare the ability of the WT and S47 variants of p53 to suppress tumor development, we isolated mouse embryonic fibroblasts (MEFs) from WT and S47 mice and transformed them with the oncogenes E1A and Ras, in order to generate a facile model that would allow us to study responses to therapy. WT and S47 cells grew similarly in 10% serum. However, transformed S47 cells grew significantly better under nutrient-deprived conditions. S47 transformed cells also grew with increased dynamics in a xenograft mouse model and in a tail vein model of metastasis. These data support the premise that the S47 variant of p53 is significantly impaired as a tumor suppressor. We found that, for the majority of conventional genotoxic drugs, S47 tumor cells are resistant, compared to tumor cells with WT p53. In order to identify novel compounds that preferentially target S47 tumor cells, we performed a drug screen on WT and S47 transformed MEFs, using a library of over 200 conventional and experimental chemotherapeutic drugs. We found that S47 cells are far more sensitive to the class of bromodomain inhibitors, specifically BET inhibitors. Using short-term (96 hrs, Alamar Blue) cell viability assays, we found that S47 transformed cells were approximately 5-fold more sensitive to OTX-015, a BET inhibitor currently in clinical trials. We also found that S47 cells were significantly impaired in their ability to form colonies when pretreated for 24 hours with OTX-015. These data highlight the relevance of targeted therapy for patients harboring the S47 variant of p53, and suggest that BET inhibitors may preferentially target S47 tumors.

Citation Format: Thibaut Barnoud, Subhasree Basu, Che-Pei Kung, Matthew Reiss, Rugang Zhang, Maureen Murphy. BET inhibitors show superior ability to suppress the progression of tumors containing the Pro47Ser single-nucleotide polymorphism of p53 [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 B210.
Abstract CN05-01: DNA damage signatures and practical use
Authors: Nik-Zainal Serena
Published: August 2018

A cancer genome is a historical account of the mutagenic activity that has occurred throughout the development of the tumor. Indeed, every mutation matters. While driver mutations were the main focus of cancer research for a long time, passenger mutational signatures, the imprints of DNA damage and DNA repair processes that have been operative during tumorigenesis, are also biologically informative (1-5). We previously outlined the methods for identifying and quantifying base substitution mutational signatures present in primary human cancers (1-5). Recently, the intellectual framework of mutational signatures was extended to include six novel rearrangement signatures (6). Exploring this in >2,500 whole genome-sequenced tumors of multiple tumor types reveals how our early (and rather simplistic) thinking of mutational signatures requires critical reevaluation. There are more nuances than previously appreciated. Diving into the detail of individual mutational signatures (7), we reveal intriguing mechanistic insights into the DNA damage and repair processes that mark the landscape of cancer genomes. In some instances, our findings invite more thoughtful consideration of that relatively binary distinction between drivers and passengers. Furthermore, we demonstrate why our whole-genome profiling methods could assist in taking things to a clinical level (6-8), with mutational signatures forming an additional weapon in the arsenal of cancer diagnostics and therapeutic stratification, in the modern war against cancer.References: 1. Nik-Zainal S et al. Mutational processes molding the genomes of 21 breast cancers. Cell 2012;149:979-93 .2. Nik-Zainal S et al. The life history of 21 breast cancers. Cell 2012;149: 994-1007. 3. Helleday T, Eshtad S, Nik-Zainal S. Mechanisms underlying mutational signatures in human cancers. Nat Rev Genet 2014;15:585-98. 4. Alexandrov LB et al. Signatures of mutational processes in human cancer. Nature 2013;500:415-21. 5. Alexandrov LB, Nik-Zainal S, Wedge DC, Campbell PJ, Stratton MR. Deciphering signatures of mutational processes operative in human cancer. Cell Rep 2013;3:246-59. 6. Nik-Zainal S et al. Landscape of somatic mutations in 560 breast cancer whole-genome sequences. Nature 2016;534:47-54. 7. Glodzik D et al. A somatic-mutational process recurrently duplicates germline susceptibility loci and tissue-specific super-enhancers in breast cancers. Nat Genet 2017;49:341-48. 8. Davies H et al. HRDetect is a predictor of BRCA1 and BRCA2 deficiency based on mutational signatures. Nat Med 2017;23:517-25.

Citation Format: Serena Nik-Zainal. DNA damage signatures and practical use [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 CN05-01.
Abstract CN05-02: Novel mechanisms of PARP inhibitor resistance
Authors: D'Andrea Alan D.
Published: August 2018

Large-scale genomic studies have demonstrated that approximately 50% of high-grade serous ovarian cancers (HGSOCs) harbor genetic and epigenetic alterations in homologous recombination repair (HRR) pathway genes. The most commonly altered HRR genes are BRCA1 and BRCA2, followed by other Fanconi anemia genes including FANCN/PALB2, FANCO/RAD51, FANCJ/BRIP, and FANCA. Loss of HRR causes genomic instability, hyperdependence on alternative DNA repair mechanisms, and enhanced sensitivity to platinum analogues, topoisomerase inhibitors, and PARP inhibitors (PARPi). The synthetic lethal interaction with PARPi is being exploited therapeutically in diverse clinical contexts and most notably in ovarian cancer where multiple PARPi have been FDA approved. PARP inhibitor resistance has already emerged as a vexing clinical problem for the treatment of BRCA1/2-deficient tumors. The most prevalent mechanism of PARPi resistance is secondary events that cancel the original HRR alteration and restore HRR proficiency. However, PARPi resistance may still develop without restoration of HRR proficiency via disruption of multiple proteins, such as PTIP or CHD4, that leads to replication fork (RF) stabilization. Importantly, this latter mechanism–namely, the restoration of RF stability–appears to be a highly prevalent mechanism of PARPi resistance in vitro and in vivo, particularly in tumor cells with an underlying BRCA2 deficiency. Due to their underlying deficiency in BRCA2 and inability to generate RAD51 nucleofilaments, these tumor cells are unable to restore HRR mechanisms. Instead, these cells acquire PARPi resistance by limiting the nucleolytic degradation of their stalled replication forks. We have recently made the surprising observation that BRCA2-deficient tumors can become resistant to PARPi by downregulating the expression of the polycomb repressive complex PRC2, a methyltransferase complex containing EZH2, SUZ12, EED, and RbAp48. Importantly, downregulation of PRC2 results in the reduced recruitment of the nuclease MUS81 to the RF, thereby providing a novel mechanism of RF protection and PARPi resistance. A molecular understanding of PARPi resistance mechanisms may allow the generation of a new class of drugs or a repurposing of existing drugs, which may reverse this resistance and extend the use of PARPi to more tumor types.

Citation Format: Alan D. D'Andrea. Novel mechanisms of PARP inhibitor resistance [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 CN05-02.