Discovery of a Novel ATP-Competitive MEK Inhibitor DS03090629 that Overcomes Resistance Conferred by BRAF Overexpression in BRAF-Mutated Melanoma.

Patients with melanoma with activating BRAF mutations (BRAF V600E/K) initially respond to combination therapy of BRAF and MEK inhibitors. However, their clinical efficacy is limited by acquired resistance, in some cases driven by amplification of the mutant BRAF gene and subsequent reactivation of the MAPK pathway. DS03090629 is a novel and orally available MEK inhibitor that inhibits MEK in an ATP-competitive manner. In both in vitro and in vivo settings, potent inhibition of MEK by DS03090629 or its combination with the BRAF inhibitor dabrafenib was demonstrated in a mutant BRAF-overexpressing melanoma cell line model that exhibited a higher MEK phosphorylation level than the parental cell line and then became resistant to dabrafenib and the MEK inhibitor trametinib. DS03090629 also exhibited superior efficacy against a melanoma cell line-expressing mutant MEK1 protein compared with dabrafenib and trametinib. Biophysical analysis revealed that DS03090629 retained its affinity for the MEK protein regardless of its phosphorylation status, whereas the affinity of trametinib declined when the MEK protein was phosphorylated. These results suggest that DS03090629 may be a novel therapeutic option for patients who acquire resistance to the current BRAF- and MEK-targeting therapies.

Novel Antibody Exerts Antitumor Effect through Downregulation of CD147 and Activation of Multiple Stress Signals.

CD147 is an immunoglobulin-like receptor that is highly expressed in various cancers and involved in the growth, metastasis, and activation of inflammatory pathways via interactions with various functional molecules, such as integrins, CD44, and monocarboxylate transporters. Through screening of CD147-targeting antibodies with antitumor efficacy, we discovered a novel rat monoclonal antibody #147D. This humanized IgG4-formatted antibody, h4#147D, showed potent antitumor efficacy in xenograft mouse models harboring the human PDAC cell line MIA PaCa-2, HCC cell line Hep G2, and CML cell line KU812, which featured low sensitivity to the corresponding standard-of-care drugs (gemcitabine, sorafenib, and imatinib, respectively). An analysis of tumor cells derived from MIA PaCa-2 xenograft mice treated with h4#147D revealed that cell surface expression of CD147 and its binding partners, including CD44 and integrin α3ß1/α6ß1, was significantly reduced by h4#147D. Inhibition of focal adhesion kinase (FAK), activation of multiple stress responsible signal proteins such as c-JunN-terminal kinase (JNK) and mitogen-activated protein kinase p38 (p38MAPK), and expression of SMAD4, as well as activation of caspase-3 were obviously observed in the tumor cells, suggesting that h4#147D induced tumor shrinkage by inducing multiple stress responsible signals. These results suggest that the anti-CD147 antibody h4#147D offers promise as a new antibody drug candidate.

A promiscuous fatty acid ω-hydroxylase CYP94A90 is likely to be involved in biosynthesis of a floral nitro compound in loquat (Eriobotrya japonica).

Nitro groups are often associated with synthetically manufactured compounds such as medicines and explosives, and rarely with natural products. Loquat emits a nitro compound, (2-nitroethyl)benzene, as a flower scent. The nitro compound exhibits fungistatic activity and is biosynthesised from l-phenylalanine via (E/Z)-phenylacetaldoxime. Although aldoxime-producing CYP79s have been intensively studied, it is unclear what enzymes form nitro groups from aldoximes either in plants or in other organisms. Here, we report the identification of two cytochrome P450s that are likely to be involved in (2-nitroethyl)benzene biosynthesis in loquat through differential gene expression analysis using RNA-seq and functional identification using yeast and tobacco. CYP79D80 and CYP94A90 catalysed the formation of (E/Z)-phenylacetaldoxime from l-phenylalanine and (2-nitroethyl)benzene from the aldoxime, respectively. Expression profiles of CYP79D80 and CYP94A90 were correlated with the emission of (2-nitroethyl)benzene from loquat flowers. CYP94A90 also functioned as a fatty acid ω-hydroxylase as do other CYP94A fatty acid ω-hydroxylases. The CYP94As tested from other plants were all found to catalyse the formation of (2-nitroethyl)benzene from (E/Z)-phenylacetaldoxime. CYP79D80 and CYP94A90 are likely to operate in concert to biosynthesise (2-nitroethyl)benzene in loquat. CYP94A90 and other CYP94As are 'promiscuous fatty acid ω-hydroxylases', catalysing the formation of nitro groups from aldoximes, and are widely distributed in dicot plants.

The regulation of glucose and lipid homeostasis via PLTP as a mediator of BAT-liver communication.

While brown adipose tissue (BAT) is well-recognized for its ability to dissipate energy in the form of heat, recent studies suggest multifaced roles of BAT in the regulation of glucose and lipid homeostasis beyond stimulating thermogenesis. One of the functions involves interorgan communication with metabolic organs, such as the liver, through BAT-derived secretory factors, a.k.a., batokine. However, the identity and the roles of such mediators remain insufficiently understood. Here, we employed proteomics and transcriptomics in human thermogenic adipocytes and identified previously unappreciated batokines, including phospholipid transfer protein (PLTP). We found that increased circulating levels of PLTP, via systemic or BAT-specific overexpression, significantly improve glucose tolerance and insulin sensitivity, increased energy expenditure, and decrease the circulating levels of cholesterol, phospholipids, and sphingolipids. Such changes were accompanied by increased bile acids in the circulation, which in turn enhances glucose uptake and thermogenesis in BAT. Our data suggest that PLTP is a batokine that contributes to the regulation of systemic glucose and lipid homeostasis as a mediator of BAT-liver interorgan communication.

Structure-Based Design and Synthesis of an Isozyme-Selective MTHFD2 Inhibitor with a Tricyclic Coumarin Scaffold.

Methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) plays a key role in one-carbon (1C) metabolism in human mitochondria, and its high expression correlates with poor survival of patients with various types of cancer. An isozyme-selective MTHFD2 inhibitor is highly attractive for potential use in cancer treatment. Herein, we disclose a novel isozyme-selective MTHFD2 inhibitor DS44960156, with a tricyclic coumarin scaffold, which was initially discovered via high-throughput screening (HTS) and improved using structure-based drug design (SBDD). DS44960156 would offer a good starting point for further optimization based on the following features: (1) unprecedented selectivity (>18-fold) for MTHFD2 over MTHFD1, (2) a molecular weight of less than 400, and (3) good ligand efficiency (LE).

Structure-Activity Relationship Studies of 3- or 4-Pyridine Derivatives of DS-6930.

Derivatization efforts were continued to discover backups for a potent selective PPARγ modulator, DS-6930. In this Letter, the replacement of 2-pyridine ring in DS-6930 with 3- or 4-pyridyl group is reported. As the introduction of substituents on the pyridine ring did not provide potent partial agonists, modifications of benzimidazole ring were explored to discover potent intermediate agonists. 4'-Alkoxy substituted benzimidazoles failed to show potent efficacy in vivo, whereas 7'-fluoro benzimidazole 3g (DS19161384) was found to result in robust plasma glucose reductions with excellent DMPK profiles.

Discovery of DS-6930, a potent selective PPARγ modulator. Part II: Lead optimization.

Attempts were made to reduce the lipophilicity of previously synthesized compound (II) for the avoidance of hepatotoxicity. The replacement of the left-hand side benzene with 2-pyridine resulted in the substantial loss of potency. Because poor membrane permeability was responsible for poor potency in vitro, the adjustment of lipophilicity was examined, which resulted in the discovery of dimethyl pyridine derivative (I, DS-6930). In preclinical studies, DS-6930 demonstrated high PPARγ agonist potency with robust plasma glucose reduction. DS-6930 maintained diminished PPARγ-related adverse effects upon toxicological evaluation in vivo, and demonstrated no hepatotoxicity. Cofactor recruitment assay showed that several cofactors, such as RIP140 and PGC1, were significantly recruited, whereas several canonical factors was not affected. This selective cofactor recruitment was caused due to the distinct binding mode of DS-6930. The calcium salt, DS-6930b, which is expected to be an effective inducer of insulin sensitization without edema, could be evaluated clinically in T2DM patients.

Discovery of DS-6930, a potent selective PPARγ modulator. Part I: Lead identification.

The lead identification of a novel potent selective PPARγ agonist, DS-6930 is reported. To avoid PPARγ-related adverse effects, a partial agonist was designed to prevent the direct interaction with helix 12 of PPARγ-LBD. Because the TZD group is known to interact with helix 12, the TZD in efatutazone (CS-7017) was replaced to discover novel PPARγ intermediate partial agonist 8i. The optimization of 8i yielded 13ac with high potency in vitro. Compound 13ac exhibited robust plasma glucose lowering effects comparable to those of rosiglitazone (3 mg/kg) in Zucker diabetic fatty rats. Upon toxicological evaluation, compound 13ac (300 mg/kg) induced hemodilution to a lower extent than rosiglitazone; however, 13ac elevated liver enzyme activities. X-ray crystallography revealed no direct interaction of 13ac with helix 12, and the additional lipophilic interactions are also suggested to be related to the maximum transcriptional activity of 13ac.

A novel inhibitor stabilizes the inactive conformation of MAPK-interacting kinase 1.

Mitogen-activated protein kinase (MAPK)-interacting kinases 1 (Mnk1) and 2 (Mnk2) modulate translation initiation through the phosphorylation of eukaryotic translation initiation factor 4E, which promotes tumorigenesis. However, Mnk1 and Mnk2 are dispensable in normal cells, suggesting that the inhibition of Mnk1 and Mnk2 could be effective in cancer therapy. To provide a structural basis for Mnk1 inhibition, a novel Mnk1 inhibitor was discovered and the crystal structure of Mnk1 in complex with this inhibitor was determined. The crystal structure revealed that the inhibitor binds to the autoinhibited state of Mnk1, stabilizing the Mnk-specific DFD motif in the DFD-out conformation, thus preventing Mnk1 from switching to the active conformation and thereby inhibiting the kinase activity. These results provide a valuable platform for the structure-guided design of Mnk1 inhibitors.

Discovery and structure-guided fragment-linking of 4-(2,3-dichlorobenzoyl)-1-methyl-pyrrole-2-carboxamide as a pyruvate kinase M2 activator.

Tumor cells switch glucose metabolism to aerobic glycolysis by expressing the pyruvate kinase M2 isoform (PKM2) in a low active form, providing glycolytic intermediates as building blocks for biosynthetic processes, and thereby supporting cell proliferation. Activation of PKM2 should invert aerobic glycolysis to an oxidative metabolism and prevent cancer growth. Thus, PKM2 has gained attention as a promising cancer therapy target. To obtain novel PKM2 activators, we conducted a high-throughput screening (HTS). Among several hit compounds, a fragment-like hit compound with low potency but high ligand efficiency was identified. Two molecules of the hit compound bound at one activator binding site, and the molecules were linked based on the crystal structure. Since this linkage succeeded in maintaining the original position of the hit compound, the obtained compound exhibited highly improved potency in an in vitro assay. The linked compound also showed PKM2 activating activity in a cell based assay, and cellular growth inhibition of the A549 cancer cell line. Discovery of this novel scaffold and binding mode of the linked compound provides a valuable platform for the structure-guided design of PKM2 activators.

Discovery and structure-guided optimization of tert-butyl 6-(phenoxymethyl)-3-(trifluoromethyl)benzoates as liver X receptor agonists.

To obtain potent liver X receptor (LXR) agonists, a structure-activity relationship study was performed on a series of tert-butyl benzoate analogs. As the crystal structure analysis suggested applicable interactions between the LXR ligand-binding domain and the ligands, two key functional groups were introduced. The introduction of the hydroxyl group on the C6-position of the benzoate part enhanced the agonistic activity in a cell-based assay, and the carboxyl group in terminal improved the pharmacokinetic profile in mice, respectively. The obtained compound 32b increased blood ABCA1 mRNA expression without plasma TG elevation in both mice and cynomolgus monkeys.

Design and discovery of new (3S,5R)-5-[4-(2-chlorophenyl)-2,2-dimethyl-5-oxopiperazin-1-yl]piperidine-3-carboxamides as potent renin inhibitors.

Utilizing X-ray crystal structure analysis, (3S,5R)-5-[4-(2-chlorophenyl)-2,2-dimethyl-5-oxopiperazin-1-yl]piperidine-3-carboxamides were designed and identified as renin inhibitors. The most potent compound 15 demonstrated favorable pharmacokinetic and pharmacodynamic profiles in rat.

Synthesis and biological evaluation of novel (-)-Cercosporamide derivatives as potent selective PPARγ modulators.

Selective peroxisome proliferator-activated receptor gamma (PPARγ) modulators are expected to be a novel class of drugs improving plasma glucose levels without PPARγ-related adverse effects. As a continuation of our studies for (-)-Cercosporamide derivatives as selective PPARγ modulators, we synthesized substituted naphthalene type compounds and identified the most potent compound 15 (EC(50) = 0.94 nM, E(max) = 38%). Compound 15 selectively activated PPARγ transcription and did not activate PPARα and PPARδ. The potassium salt of compound 15 showed a high solubility and a good oral bioavailability (58%). Oral administration of the potassium salt remarkably improved the plasma glucose levels of female Zucker diabetic fatty rats at 1 mg/kg. Moreover, it did not cause a plasma volume increase or a cardiac enlargement in Wistar-Imamichi rats, even at 100 mg/kg.

Substituents at the naphthalene C3 position of (-)-Cercosporamide derivatives significantly affect the maximal efficacy as PPARγ partial agonists.

Peroxisome proliferator-activated receptor gamma (PPARγ) is a potential drug target for treating type 2 diabetes. The selective PPARγ modulators (SPPARMs), which partially activate the PPARγ transcriptional activity, are considered to improve the plasma glucose level with attenuated PPARγ related adverse effects. However, the relationships between desired pharmacological profiles and ligand specific PPARγ transcriptional profiles have been unclear. And there is also little knowledge of how to control ligand specific PPARγ transcriptional profiles. Herein, we present synthesis of novel derivatives containing substituent at naphthalene C3 position of compound 1. The novel derivatives showed various maximal efficacies as PPARγ partial agonist.

Discovery of DS-8108b, a Novel Orally Bioavailable Renin Inhibitor.

A novel orally bioavailable renin inhibitor, DS-8108b (5), showing potent renin inhibitory activity and excellent in vivo efficacy is described. We report herein the synthesis and pharmacological effects of 5 including renin inhibitory activity in vitro, suppressive effects of ex vivo plasma renin activity (PRA) in cynomolgus monkey, pharmacokinetic data, and blood pressure-lowering effects in an animal model. Compound 5 demonstrated inhibitory activities toward human renin (IC50 = 0.9 nM) and human and monkey PRA (IC50 = 1.9 and 6.3 nM, respectively). Oral administration of single doses of 3 and 10 mg/kg of 5 in cynomolgus monkey on pretreatment with furosemide led to dose-dependent significant reductions in ex vivo PRA and sustained lowering of mean arterial blood pressure for more than 12 h.

Pharmacology and in vitro profiling of a novel peroxisome proliferator-activated receptor γ ligand, Cerco-A.

Peroxisome proliferator-activated receptor γ (PPARγ; NR1C3) is known as a key regulator of adipocytogenesis and the molecular target of thiazolidinediones (TZDs), also known as antidiabetic agents. Despite the clinical benefits of TZDs, their use is often associated with adverse effects including peripheral edema, congestive heart failure, and weight gain. Here we report the identification and characterization of a non-thiazolidinedione PPARγ partial agonist, Cerco-A, which is a derivative of the natural product, (-)-cercosporamide. Cerco-A was found to be a binder of the PPARγ ligand-binding domain in a ligand competitive binding assay and showed a unique cofactor recruitment profile compared to rosiglitazone. A crystal structure analysis revealed that Cerco-A binds to PPARγ without direct hydrogen bonding to helix12. In PPARγ transcriptional activation assay and an adipocyte differentiation assay, Cerco-A was a potent partial agonist of PPARγ. After a 14-day oral administration, once per day of Cerco-A in Zucker diabetic fatty (ZDF) rats, an apparent decrease of plasma glucose and triglyceride was observed, as with pioglitazone. To evaluate drug safety, Cerco-A was administered for 13 days orally in non-diabetic Zucker fatty (ZF) rats. Each of the hemodilution parameters (hematocrit, red blood cells number, and hemoglobin), which are considered as undesirable effects of TZDs, was improved significantly compared to pioglitazone. While Cerco-A showed body weight gain, as with pioglitazone, Cerco-A had significantly lower effects on heart and white adipose tissues weight gain. The results suggest that Cerco-A offers beneficial effects on glycemic control with attenuated undesirable side effects.

Rh(I)-catalyzed intramolecular [2 + 2 + 1] cycloaddition of allenenes: Construction of bicyclo[4.3.0]nonenones with an angular methyl group and tricyclo[6.4.0.0]dodecenone.

The [RhCl(CO)dppp](2)-catalyzed intramolecular carbonylative [2 + 2 + 1] cycloaddition of allenenes was developed to prepare bicyclo[4.3.0]nonenones possessing a methyl group at the ring junction, which is difficult to achieve by the Pauson-Khand reaction of the corresponding enynes. This method also provided a new procedure for the construction of the tricyclo[6.4.0.0(1,5)]dodecenone framework in a satisfactory yield.

Discovery of a novel selective PPARgamma modulator from (-)-Cercosporamide derivatives.

In an investigation of (-)-Cercosporamide derivatives with a plasma glucose-lowering effect, we found that N-benzylcarboxamide derivative 4 was a partial agonist of PPARgamma. A SAR study of the substituents on carboxamide nitrogen afforded the N-(1-naphthyl)methylcarboxamide derivative 23 as the most potent selective PPARgamma modulator. An X-ray crystallography study revealed that compound 23 bounded to the PPARgamma ligand binding domain in a unique way without any interaction with helix12. Compound 23 displayed a potent plasma glucose-lowering effect in db/db mice without the undesirable increase in body fluid and heart weight that is typically observed when PPARgamma full agonists are administrated.

Indoline derivatives I: synthesis and factor Xa (FXa) inhibitory activities.

A series of bisamidine derivatives each having a ring structure in the center of the molecule was synthesized and their Factor Xa (FXa) inhibitory activities were evaluated. Among them, some indoline derivatives showed potent inhibitory activities in vitro. In particular, (R)-18a having an (R)-configuration at the 2-position of the indoline ring exhibited the most potent FXa inhibitory activity in vitro, more potent than DX-9065a. Furthermore, (R)-18a exhibited more potent anticoagulant activity than DX-9065a. We also succeeded in obtaining an X-ray crystal structure of FXa bound with (R)-18a.

Sequence-specific suppression of mdr1a/1b expression in mice via RNA interference.

PURPOSE: RNA interference (RNAi) is a powerful tool for silencing gene expression posttranscriptionally. The purpose of this study was to examine whether in vivo RNAi can be induced against endogenous mdr1a/1b in adult mice and to assess the feasibility of generating P-glycoprotein (P-gp) knockdown mice based on RNAi by a very simple intravenous injection of synthetic small interfering RNA (siRNAs) or siRNA-expressing plasmid DNAs. METHODS: The targeted sequences for silencing mdr1a specifically or mdr1a/1b simultaneously were examined in an in vitro study using a mouse colon carcinoma cell line, colon26 cells, in culture. Mice were repeatedly treated with intravenous synthetic siRNAs or siRNA-expressing plasmid DNAs in naked form administered via a large-volume and high-speed injection, i.e., the hydrodynamics-based procedure. The amount of targeted mRNA and P-gp in the liver were determined by real-time polymerase chain reaction and Western blot analysis, respectively. RESULTS: Among several targeted sequences, two and one optimized sequences were selected for mdr1a and mdr1a/1b, respectively, in the in vitro study. Following administration of synthetic siRNAs or siRNA-expressing plasmid DNAs directed against mdr1a, the mRNA level in the liver was significantly reduced to approximately 50-60% of that in control mice. Furthermore, a slight reduction was observed at the protein level. Similar results were obtained in the experiments using siRNA-expressing pDNA directed against mdr1a/1b. CONCLUSIONS: Our results demonstrate that sequence-specific suppression of mdr1 gene expression is possible at the mRNA level as well as the protein level in mice following intravenous delivery of siRNA effectors.