Yoshihiko Satoh

Adenosine 3',5'-cyclic monophosphate as a possible mediator of rotational behaviour induced by dopaminergic receptor stimulation in rats lesioned unilaterally in the substantia nigra.

A possible involvement of c-AMP in the rotational behaviour induced by a stimulation of dopamine receptors in corpus striatum of rats was investigated. Rats were lesioned unilaterally in the substantia nigra with 6-hydroxydopamine. Intraventricular injection of dopamine, norepinephrine and apomorphine induced rotational behaviour towards the intact side as did dibutyryl c-AMP (dB-c-AMP). Dopamine, norepinephrine and apomorphine could activate adenylate cyclase in homogenates of caudate nucleus. The activation by dopamine was blocked by haloperidol. I.p. injected apomorphine increased c-AMP content bilaterally in caudate nucleus and caused turning towards the intact side; theophylline potentiated and haloperidol blocked the effect. In non-lesioned rats, dopamine and norepinephrine, when injected unilaterally into the caudate nucleus, elicited truning twoards the non-injected side if the rats were pretreated with reserpine and tranylcypromine. c-AMP and dB-c-AMP given similarly to rats pretreated with theophylline also produced turning towards the non-injected side regardless the pretreatment with reserpine and tranylcypromine. All these results emphasize the possibility that c-AMP acts as a second messenger in the central dopaminergic pathway in rats. The supersensitivity of the dopaminergic system which developed after denervation is also discussed.

In vitro and in vivo antitumor activities of T-3764518, a novel and orally available small molecule stearoyl-CoA desaturase 1 inhibitor

Abstract Most cancer cells are characterized by elevated lipid biosynthesis. The rapid proliferation of cancer cells requires de novo synthesis of fatty acids. Stearoyl‐CoA desaturase‐1 (SCD1), a key enzyme for lipogenesis, is overexpressed in various types of cancer and plays an important role in cancer cell proliferation. Therefore, it has been studied as a candidate target for cancer therapy. In this study, we demonstrate the pharmacological properties of T‐3764518, a novel and orally available small molecule inhibitor of SCD1. T‐3764518 inhibited stearoyl‐CoA desaturase‐catalyzed conversion of stearoyl‐CoA to oleoyl‐CoA in colorectal cancer HCT‐116 cells and their growth. Further, it slowed tumor growth in an HCT‐116 and a mesothelioma MSTO‐211H mouse xenograft model. Comprehensive lipidomic analyses revealed that T‐3764518 increases the membrane ratio of saturated: unsaturated fatty acids in various lipid species such as phosphatidylcholines and diacylglycerols in both cultured cells and HCT‐116 xenografts. Treatment‐associated lipidomic changes were followed by activated endoplasmic reticulum (ER) stress responses such as increased immunoglobulin heavy chain‐binding protein expression in HCT‐116 cells. These T‐3764518‐induced changes led to an increase in cleaved poly (ADP‐ribose) polymerase 1 (PARP1), a marker of apoptosis. Additionally, bovine serum albumin conjugated with oleic acid, an SCD1 product, prevented cell growth inhibition and ER stress responses by T‐3764518, indicating that these outcomes were not attributable to off‐target effects. These results indicate that T‐3764518 is a promising new anticancer drug candidate.

Abstract 2823: TAK-441, a novel investigational small molecule hedgehog pathway inhibitor for use in cancer therapy

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Dysregulation of hedgehog (Hh) signal, which is caused by Hh-ligand overexpression or patched1 (Ptch1) mutation, has been found to play an important role in tumorigenesis. TAK-441 is a potent and selective smoothened (Smo) antagonist that blocks Hh signaling. In the Gli-responsive promoter-luciferase (Gli-luc) reporter assay in NIH3T3/Gli-luc cells, TAK-441 inhibited Gli transcriptional activity with an IC50 of 4.4 nM. TAK-441 also inhibited expression of human Gli1 messenger mRNA with an IC50 of 1.9 nM in MRC5 human embryonic fibroblasts. In addition, TAK-441 inhibited binding of cyclopamine, a plant-derived well-known Smo inhibitor, to human Smo on 293T cells overexpressing human Smo with an IC50 of 8.6 nM. These data suggest that TAK-441 inhibits the Hh signaling pathway through its binding to Smo. Oral administration of TAK-441 (0.5, 1, 5, 25 mg/kg QD) in mice bearing a Ptch1 (+/-), p53(−/-) medulloblastoma allograft resulted in dose-dependent antitumor activity with concomitant reduction of Gli1 mRNA expression in the tumors. Complete remissions were observed in the 25 mg/kg QD dose cohort after two consecutive weeks of treatment. Significant (p≤0.025 by one-tailed Williams test) antitumor activity was also detected in sonic hedgehog expressing human primary pancreatic and ovarian cancer xenografts when dosed at 10 and 25 mg/kg QD for two weeks, and in a colon cancer xenograft when dosed at 6.25 and 25 mg/kg BID for three weeks. In these models, the expression of tumor-associated mouse stromal Gli1 mRNA was markedly decreased following TAK-441 treatment, suggesting that Hh signaling in these tumors was driven in a paracrine mode of action. The combination of TAK-441 and rapamycin, an inhibitor of mammalian target of rapamycin (mTOR), demonstrated significantly better antitumor activity than either agent alone in human primary pancreatic cancer xenograft models (p≤0.05 by Students’ t-test). In addition, delayed tumor re-growth was observed in the TAK-441/rapamycin combination treatment group compared with the rapamycin single-agent treatment group after terminating treatment. As a result of these preclinical studies, TAK-441 has recently entered Phase I clinical studies in cancer patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2823. doi:10.1158/1538-7445.AM2011-2823

Discovery of Novel Selective Acetyl-CoA Carboxylase (ACC) 1 Inhibitors

We initiated our structure-activity relationship (SAR) studies for selective ACC1 inhibitors from 1a as a lead compound. SAR studies of bicyclic scaffolds revealed many potent and selective ACC1 inhibitors represented by 1f; however most of them had physicochemical issues, particularly low aqueous solubility and potent CYP inhibition. To address these two issues and improve the druglikeness of this chemical series, we converted the bicyclic scaffold into a monocyclic framework. Ultimately, this lead us to discover a novel monocyclic derivative 1q as a selective ACC1 inhibitor, which showed highly potent and selective ACC1 inhibition as well as acceptable solubility and CYP inhibition profiles. Since compound 1q displayed favorable bioavailability in mouse cassette dosing testing, we conducted in vivo PD studies of this compound. Oral administration of 1q significantly reduced the concentration of malonyl-CoA in HCT-116 xenograft tumors at doses of more than 30 mg/kg. Accordingly, our novel series of selective ACC1 inhibitors represents a set of useful orally available research tools, as well as potential therapeutic agents for cancer and fatty acid related diseases.

Panitumumab interaction with TAS-102 leads to combinational anticancer effects via blocking of EGFR-mediated tumor response to trifluridine

Panitumumab is a monoclonal antibody developed against the human epidermal growth factor receptor (EGFR). TAS‐102 is a novel chemotherapeutic agent containing trifluridine (FTD) as the active cytotoxic component. Both panitumumab and TAS‐102 have been approved for the treatment of metastatic colorectal cancer. In this study, we revealed the mechanism underlying the anticancer effects of panitumumab/TAS‐102 combination using preclinical models. Panitumumab/FTD cotreatment showed additive antiproliferative effects in LIM1215 and synergistic antiproliferative effects in SW48 colon cancer cells. Consistent with the in vitro effects, panitumumab/TAS‐102 combination caused tumor regression in LIM1215 and COL‐01‐JCK colon cancer patient‐derived xenograft models. In LIM1215 cells, FTD induced extracellular signal‐regulated kinase (ERK)/protein kinase B (AKT)/signal transducer and activator of transcription 3 (STAT3) phosphorylation and subsequent serine/threonine phosphorylation of EGFR, while it had no effects on EGFR tyrosine phosphorylation. Panitumumab and the tyrosine kinase inhibitor erlotinib reduced the basal level of EGFR tyrosine phosphorylation and reversed FTD‐induced ERK/AKT/STAT3 and EGFR serine/threonine phosphorylation. These results suggested that FTD in combination with the basal activity of EGFR tyrosine kinase induced downstream prosurvival signaling through ERK/AKT/STAT3 phosphorylation. Collectively, we propose that panitumumab interacts with FTD by targeting EGFR‐mediated adaptive responses, thereby exerting anticancer effects when used in combination with TAS‐102. These preclinical findings provide a compelling rationale for evaluating the combination of anti‐EGFR antibodies with TAS‐102 against metastatic colorectal cancer.

Synthesis and evaluation of hedgehog signaling inhibitor with novel core system.

As we previously reported, N-methylpyrrolo[3,2-c]pyridine derivatives 1 (TAK-441) was discovered as a clinical candidate of hedgehog (Hh) signaling inhibitor by modification of the upper part. We next focused on modification of the lower part including core skeletons to discover new Hh signaling inhibitors with novel core rings. Efforts to find novel chemotypes by using X-ray single crystal structure analysis led to some potent Hh signaling inhibitors (2c, 2d, 2e, 2f) with novel core ring systems, which had benzamide moiety at the 5-position as a key component for potent activity. The suppression of Gli1 expression with these new Hh signaling inhibitors were weaker than that of compound 1 (TAK-441) because of low pharmacokinetic property. We recognized again TAK-441 is a good compound as clinical candidate with good structural and pharmacokinetic advantages.

Abstract 26: Panitumumab interacts with TAS-102 leading to combinational anti-cancer effects by blocking EGFR-mediated tumor response to trifluridine

Panitumumab is a monoclonal antibody raised against the human epidermal growth factor receptor (EGFR). TAS-102 is a novel chemotherapeutic agent containing trifluridine (FTD) as the active cytotoxic component. Both panitumumab and TAS-102 have been approved for the treatment of metastatic colorectal cancer (mCRC). In this study, we show the mechanism underlying the anti-cancer effects of the panitumumab/TAS-102 combination in preclinical models. Co-treatment with panitumumab and FTD exerted additive and synergistic anti-proliferative effects in LIM1215 and SW48 colon cancer cells, respectively. Consistent with the in vitro effects, panitumumab/TAS-102 combination led to tumor regression in LIM1215 and COL-01-JCK colon cancer patient-derived xenograft models. In LIM1215 cells, FTD induced ERK/Akt/STAT3 phosphorylation and subsequent serine/threonine phosphorylation of EGFR, while it had no effects on EGFR tyrosine phosphorylation. Panitumumab and the tyrosine kinase inhibitor erlotinib reduced the basal level of EGFR tyrosine phosphorylation and reversed the FTD-induced ERK/Akt/STAT3 and EGFR serine/threonine phosphorylation. These results suggested that FTD together with the basal activity of the EGFR tyrosine kinase induced downstream pro-survival signaling through ERK/Akt/STAT3. Collectively, we propose that panitumumab interacts with FTD by targeting EGFR-mediated adaptive responses, thereby exerting anti-cancer effects in combination with TAS-102. These preclinical findings provide a compelling rationale to evaluate anti-EGFR antibodies combined with TAS-102 against mCRC. Citation Format: Kazuhide Nakamura, Yuji Baba, Toshiya Tamura, Yoshihiko Satoh, Masamitsu Gotou, Hiroshi Sawada, Shunsuke Ebara, Kazunori Shibuya, Jumpei Soeda. Panitumumab interacts with TAS-102 leading to combinational anti-cancer effects by blocking EGFR-mediated tumor response to trifluridine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 26. doi:10.1158/1538-7445.AM2017-26

Discovery of Novel 5-(Piperazine-1-carbonyl)pyridin-2(1H)-one Derivatives as Orally eIF4A3-Selective Inhibitors

Starting from our previous eIF4A3-selective inhibitor 1a, a novel series of (piperazine-1-carbonyl)pyridin-2(1H)-one derivatives was designed, synthesized, and evaluated for identification of orally bioavailable probe molecules. Compounds 1o and 1q showed improved physicochemical and ADMET profiles, while maintaining potent and subtype-selective eIF4A3 inhibitory potency. In accord with their promising PK profiles and results from initial in vivo PD studies, compounds 1o and 1q showed antitumor efficacy with T/C values of 54% and 29%, respectively, without severe body weight loss. Thus, our novel series of compounds represents promising probe molecules for the in vivo pharmacological study of selective eIF4A3 inhibition.