Search

Androgen receptor (AR) is an important therapeutic target for prostate cancer (PCa) treatment, but prolonged use of AR antagonists has led to variant drug-resistant mutations. Since all marketed AR antagonists target the ligand binding pocket (LBP) of AR, to mitigate cross-resistance, a new drug pocket named Dimer Interface Pocket was discovered and a novel AR antagonist M17-B15 was identified. M17-B15 showed strong in vitro efficacy against PCa but had poor pharmacokinetic properties in vivo . In this study, through rational design and structure-activity relationship exploration, a series of thiadiazoleamide derivatives represented by N29 (IC 50 = 0.018 μM) were identified with dominant AR antagonistic activity and remarkable anti-PCa activity in vitro . Furthermore, N29 effectively inhibited a series of typical drug-resistant AR mutants. The improved oral bioavailability of N29 facilitated its efficacy via oral administration, significantly inhibiting LNCaP xenograft tumor in vivo , presenting a promising therapeutic application for PCa.

α-synuclein (α-syn) pathologies are central to the development of synucleinopathies including Parkinson's disease (PD). Positron emission tomography (PET) imaging of α-syn pathologies is one strategy to facilitate the diagnosis, understanding, and treatment of synucleinopathies, but has been restricted by the lack of specific α-syn PET probes. In this work, we identified 2,6-disubstituted imidazo[2,1- b ][1,3,4]thiadiazole (ITA) as a new α-syn-binding scaffold. Through autoradiography studies, we discovered an iodinated lead compound [ 125 I] ITA-3 , with moderate binding affinity (IC 50 = 55 nM) to α-syn pathologies in human PD brain sections. Modified from [ 125 I] ITA-3 , we developed a potential PET tracer, [ 18 F] FITA-2 (radiochemical yield >25%, molar activity >110 GBq/μmol), which demonstrated clear signals in α-syn-rich regions in human PD brain tissues (IC 50 = 245 nM), good brain uptake (SUV peak = 2.80 ± 0.45), and fast clearance rate in rats. Overall, [ 18 F] FITA-2 appears to be a promising candidate for α-syn PET imaging and merits further development.

Apoptosis or programmed cell death is a highly regulated process, which eliminates unwanted and damaged cells. Inhibition of apoptosis is a hallmark of cancer cells. BCL2 family proteins are known to play a vital role in the regulation of apoptosis. Overexpression of BCL2, an antiapoptotic protein, provides the advantage of prolonged survival to cancer cells. Over the years, several BCL2 inhibitors have been investigated extensively for their anticancer potential. However, most of them were abolished before clinical use due to their side effects. Previously, we had identified and characterized a novel BCL2 inhibitor, Disarib, with the potential to eliminate tumor cells in a BCL2 specific manner leading to reduction in tumor burden in multiple mouse models. Notably, a head-to-head comparison of Disarib to ABT199, the only FDA approved BCL2 inhibitor revealed that Disarib is as potent as ABT199. Recent studies using mice revealed that Disarib did not invoke significant side effects in mice. In the present study, we have investigated the acute toxicity of Disarib in Wistar rats. The bioavailability studies following exposure of Disarib in Wistar rats revealed its maximum availability in serum at 24 h following oral administration. Acute toxicity analysis revealed that even a dose as high as 2000 mg/kg of Disarib did not cause significant toxicity in rats. There was no significant variation in blood parameters or kidney and liver functions following administration of Disarib. Histological analysis of different tissues from Disarib treated groups revealed standard architecture with no observable cellular damage. Importantly, exposure to Diasrib did not result in genotoxicity as determined by micronucleus assay. Further, solubility assays revealed that besides DMSO, Disarib is also soluble in alcohol. While the high acidic condition can increase the solubility of Disarib, even a lower percentage of alcohol with acidic conditions can improve its solubility. Thus, the toxicological profile in the current study revealed no significant side effects when Disarib was administered orally to rats.

Aims: Base dissociation constants of 30 model chemicals were investigated to constitute potential determinant factors predicting the contributions of flavin-containing monooxygenases (FMOs)., Background: The contributions of FMOs to the metabolic elimination of new drug candidates could be underestimated under certain experimental conditions during drug development., Objective: A method for predicting metabolic sites and the contributions of FMOs to N-oxygenations is proposed using a molecular descriptor, the base dissociation constant (pKa base), which can be estimated in silico using commonly available chemoinformatic prediction systems., Methods: Model drugs and their oxidative pathways were surveyed in the literature to investigate the roles of FMOs in their N-oxygenations. The acid and base dissociation constants of the nitrogen moieties of 30 model substrates were estimated using well-established chemoinformatic software., Results: The base dissociation constants of 30 model chemicals were classified into two groups based on the reported optimal in vitro pH of 8.4 for FMO enzymes as a key determinant factor. Among 18 substrates (e.g., trimethylamine, benzydamine, and itopride) with pKa (base) values in the range of 8.4-9.8, all N-oxygenated metabolites were reported to be predominantly catalyzed by FMOs. Except for three cases (xanomeline; L-775,606; and tozasertib), the nine substrates with pKa (base) values in the range 2.7-7.9 were only moderately or minorly N-oxygenated by FMOs in addition to their major metabolic pathway of oxidation mediated by cytochrome P450s. N-Oxygenation of T-1032 (with a pKa of 4.8) is mediated predominantly by P450 3A5, but not by FMO1/3., Conclusion: The predicted contributions of FMOs to the N-oxygenation of drug candidates can be simply estimated using classic base dissociation constants., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

N-(5-Chlorobenzo[d]oxazol-2-yl)-4-methyl-1,2,3-thiadiazole-5-carboxamideox-amide has been identified as a potent inhibitor of Mtb H37Rv, with a minimum inhibitory concentration (MIC) of 0.42 μM. In this study, a series of substituted 2-acylamide-1,3-zole analogues were designed and synthesized, and their anti-Mtb activities were analyzed. In total, 17 compounds were found to be potent anti-Mtb agents, especially against the MDR- and XDR-MTB strains, with MIC values < 10 μM. These analogues can inhibit both drug-sensitive and drug-resistant Mtb. Four representative compounds were selected for further profiling, and the results indicate that compound 18 is acceptably safe and has favorable pharmacokinetic (PK) properties. In addition, this compound displays potent activity against Gram-positive bacteria, with MIC values in the range of 1.48-11.86 μM. The data obtained herein suggest that promising anti-Mtb candidates may be developed via structural modification, and that further research is needed to explore other compounds., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Background: GSK3β is an intracellular regulatory kinase that is dysregulated in multiple tissues in type 1 myotonic dystrophy, a rare neuromuscular disorder that manifests at any age. AMO-02 (tideglusib) inhibits GSK3β activity in preclinical models of type 1 myotonic dystrophy and promotes cellular maturation as well as normalizes aberrant molecular and behavioral phenotypes. This phase 2 study assessed the pharmacokinetics, safety and tolerability, and preliminary efficacy of AMO-02 in adolescents and adults with congenital and childhood-onset type 1 myotonic dystrophy., Methods: Sixteen subjects (aged 13 to 34 years) with congenital and childhood-onset type 1 myotonic dystrophy received 12 weeks of single-blind fixed-dose oral treatment with either 400 mg (n = 8) or 1000 mg (n = 8) AMO-02 (NCT02858908). Blood samples were obtained for pharmacokinetic assessment. Safety assessments, such as laboratory tests and electrocardiograms, as well as efficacy assessments of syndromal, cognitive, and muscular functioning, were obtained., Results: AMO-02 plasma concentrations conformed to a two-compartment model with first-order absorption and elimination, and dose-dependent increases in exposure (area under the curve) were observed. AMO-02 was generally safe and well-tolerated. No early discontinuations due to adverse events or dose adjustments of AMO-02 occurred. The majority of subjects manifested clinical improvement in their central nervous system and neuromuscular symptoms after 12 weeks of treatment compared with the placebo baseline, with a larger response noted at the 1000 mg/day dose level. AMO-02 exposure (cumulative area under the curve) was significantly correlated (P < 0.01) with change from baseline on several key efficacy assessments., Conclusion: AMO-02 has favorable pharmacokinetic and clinical risk/benefit profiles meriting further study as a potential treatment for congenital and childhood-onset type 1 myotonic dystrophy., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Background Despite reductions in door-to-balloon times for primary coronary intervention, mortality from ST-segment-elevation myocardial infarction has plateaued. Early pre-primary coronary intervention treatment of ST-segment-elevation myocardial infarction with glycoprotein IIb/IIIa inhibitors improves pre-primary coronary intervention coronary flow, limits infarct size, and improves survival. We report the first human use of a novel glycoprotein IIb/IIIa inhibitor designed for subcutaneous first point-of-care ST-segment-elevation myocardial infarction treatment. Methods and Results Healthy volunteers and patients with stable coronary artery disease receiving aspirin received escalating doses of RUC-4 or placebo in a sentinel-dose, randomized, blinded fashion. Inhibition of platelet aggregation (IPA) to ADP (20 μmol/L), RUC-4 blood levels, laboratory evaluations, and clinical assessments were made through 24 hours and at 7 days. Doses were increased until reaching the biologically effective dose (the dose producing ≥80% IPA within 15 minutes, with return toward baseline within 4 hours). In healthy volunteers, 15 minutes after subcutaneous injection, mean±SD IPA was 6.9%+7.1% after placebo and 71.8%±15.0% at 0.05 mg/kg (n=6) and 84.7%±16.7% at 0.075 mg/kg (n=6) after RUC-4. IPA diminished over 90 to 120 minutes. In patients with coronary artery disease, 15 minutes after subcutaneous injection of placebo or 0.04 mg/kg (n=2), 0.05 mg/kg (n=6), and 0.075 mg/kg (n=18) of RUC-4, IPA was 14.6%±11.7%, 53.6%±17.0%, 76.9%±10.6%, and 88.9%±12.7%, respectively. RUC-4 blood levels correlated with IPA. Aspirin did not affect IPA or RUC-4 blood levels. Platelet counts were stable and no serious adverse events, bleeding, or injection site reactions were observed. Conclusions RUC-4 provides rapid, high-grade, limited-duration platelet inhibition following subcutaneous administration that appears to be safe and well tolerated. Registration URL: https://www.clini​caltr​ials.gov; Unique identifier: NTC03844191.

Padsevonil is an antiepileptic drug (AED) candidate synthesized in a medicinal chemistry program initiated to rationally design compounds with high affinity for synaptic vesicle 2 (SV2) proteins and low-to-moderate affinity for the benzodiazepine binding site on GABA A receptors. The pharmacological profile of padsevonil was characterized in binding and electrophysiological experiments. At recombinant SV2 proteins, padsevonil's affinity for SV2A was greater than that of levetiracetam and brivaracetam (pKi 8.5, 5.2, and 6.6, respectively). Unlike the latter AEDs, both selective SV2A ligands, padsevonil also displayed high affinity for the SV2B and SV2C isoforms (pKi 7.9 and 8.5, respectively). Padsevonil's interaction with SV2A differed from that of levetiracetam and brivaracetam; it exhibited slower binding kinetics: dissociation t 1/2 30 minutes from the human protein at 37°C compared with <0.5 minute for levetiracetam and brivaracetam. In addition, its binding was not potentiated by the allosteric modulator UCB1244283. At recombinant GABA A receptors, padsevonil displayed low to moderate affinity (pIC 50 ≤6.1) for the benzodiazepine site, and in electrophysiological studies, its relative efficacy compared with zolpidem (full-agonist reference drug) was 40%, indicating partial agonist properties. In in vivo (mice) receptor occupancy studies, padsevonil exhibited SV2A occupancy at low ED 50 (0.2 mg/kg) and benzodiazepine site occupancy at higher doses (ED 50 36 mg/kg), supporting in vitro results. Padsevonil's selectivity for its intended targets was confirmed in profiling studies, where it lacked significant effects on a wide variety of ion channels, receptors, transporters, and enzymes. Padsevonil is a first-in-class AED candidate with a unique target profile allowing for presynaptic and postsynaptic activity. SIGNIFICANCE STATEMENT: Padsevonil is an antiepileptic drug candidate developed as a single molecular entity interacting with both presynaptic and postsynaptic targets. Results of in vitro and in vivo radioligand binding assays confirmed this target profile: padsevonil displayed nanomolar affinity for the three synaptic vesicle 2 protein isoforms (SV2A, B, and C) and micromolar affinity for the benzodiazepine binding site on GABA A receptors. Furthermore, padsevonil showed greater affinity for and slower binding kinetics at SV2A than the selective SV2A ligands, levetiracetam, and brivaracetam., (Copyright © 2019 The Author(s).)

Transforming growth factor (TGF-β), a key mediator of tumor growth and metastasis, has been recognized as an important cancer drug target. A series of benzo[c][1,2,5]thiadiazol-5-yl imidazoles (14a-g) and thieno[3,2-c]-pyridin-2-yl imidazoles (20a-g) were designed, synthesized, and evaluated for their activin receptor-like kinase 5 (ALK5) activities. Among these compounds, 14c showed the highest activity (IC 50  = 0.008 μM) against ALK5 kinase, which was 16.1-fold and 1.8-fold higher than those of positive control compounds LY-2157299 (IC 50  = 0.129 μM) and EW-7197 (IC 50  = 0.014 μM), respectively. Compound 14g (350) showed the highest selectivity index of ALK5 against p38α MAP kinase, which was significantly higher than that of positive control compounds LY-2157299 (4) and EW-7197 (211). The inhibitory effects of compound 14c on TGF-β-induced Smad signaling and cell motility were studied in SPC-A1, HepG2 and HUVEC cells using western blot analysis and wound healing assay. ADMET prediction analysis showed that compounds 14c and 14g had good pharmacokinetics and drug-likeness behaviors., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The development of new antihyperlipidemic agents with higher potency and lower side effects is of high priority. In this study, 1,3,4 thiadiazole Schiff base derivatives were synthesized as potential peroxisome proliferation-activated receptor-α (PPARα) agonists and characterized using elemental analysis, FTIR, 1 H-NMR, 13 C-NMR and mass spectroscopy and then tested for their hypolipidemic activity in Triton WR-1339-induced acute hyperlipidemic rat model in comparison with bezafibrate. The compounds showed significant hypolipidemic activity. Induced fit docking showed that the compounds are potential activators of PPARα with binding scores - 8.00 Kcal/mol for 2,5-bis(4-hydroxybenzylidenamino)-1,3,4-thiadiazole. PCR array analysis showed an increase in the expression of several genes involved in lipid metabolism through mitochondrial fatty acid β oxidation and are part of PPARα signaling pathway including Acsm3, Fabp4 and Hmgcs1. Gene expression of Lrp12 and Lrp1b involved in LDL uptake by liver cells and Cyp7a1 involved in cholesterol catabolism were also found to be upregulated.

Tumors have evolved a variety of methods to reprogram conventional metabolic pathways to favor their own nutritional needs, including glutaminolysis, the first step of which is the hydrolysis of glutamine to glutamate by the amidohydrolase glutaminase 1 (GLS1). A GLS1 inhibitor could potentially target certain cancers by blocking the tumor cell's ability to produce glutamine-derived nutrients. Starting from the known GLS1 inhibitor bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl)ethyl sulfide, we describe the medicinal chemistry evolution of a series from lipophilic inhibitors with suboptimal physicochemical and pharmacokinetic properties to cell potent examples with reduced molecular weight and lipophilicity, leading to compounds with greatly improved oral exposure that demonstrate in vivo target engagement accompanied by activity in relevant disease models.

DS-2969b is a novel GyrB inhibitor in development for the treatment of Clostridium difficile infection. The aim of this study was to assess the safety, tolerability, pharmacokinetics, and effects on normal gastrointestinal microbiota groups of single daily oral ascending doses of DS-2969b in healthy subjects. The study enrolled 6 sequential ascending dose cohorts (6 mg, 20 mg, 60 mg, 200 mg, 400 mg, and 600 mg). In each cohort, 6 subjects were administered DS-2969b and 2 subjects were administered matching placebo. DS-2969b was safe and well tolerated at all dose levels examined. All adverse events related to DS-2969b were mild to moderate in severity and predominantly related to the gastrointestinal tract. DS-2969a (free form of DS-2969b) plasma concentrations increased with increasing doses; however, both the maximum serum concentration and area under the plasma concentration-time curve generally increased less than dose proportionally. DS-2969a was predominantly eliminated in the urine, with feces as a minor route of elimination. While the overall proportion of DS-2969a eliminated in the feces was low, target fecal levels sufficient for C. difficile eradication were achieved within 24 hours of administration with doses of 60 mg or higher. In exploratory analyses, DS-2969b appeared to reduce bacterial counts in 8 of the 25 groups of normal intestinal microbiota examined, suggesting that DS-2969b has only a mild effect on intestinal microbiota. Data from this study support and encourage further development of DS-2969b as a novel treatment for C. difficile infection., (© 2018, The American College of Clinical Pharmacology.)

One lead 3,6-disubstituted 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole was identified as an inhibitor of shikimate dehydrogenase with antitubercular activity. Following up this compound, we optimized the lead through systematic modification of the 3 and 6 positions. The antitubercular activities in vitro, shikimate dehydrogenase inhibitory activities and cytotoxicity of derivatives were determined. We found IMB-SD62 with lower cytotoxicity and better activity. Thus, we studied the in vivo efficacy of IMB-SD62 against Mycobacterium tuberculosis and pharmacokinetics of IMB-SD62. In vivo acute M. tuberculosis H37Rv infection assay, IMB-SD62 showed antitubercular activity with the mean lung CFU counts decreasing 1.7 lg. The plasma pharmacokinetics study in rats showed that the oral bioavailability of IMB-SD62 was 14% and the half time was 1.05 h. The results of tissue distribution indicated that IMB-SD62 was mainly absorbed by liver and lung. In vitro metabolism study suggested that the metabolic ways of IMB-SD62 were dealkylated, oxidized and demethylated. CYP enzyme inhibition of IMB-SD62 in human liver microsomes was also evaluated. IMB-SD62 showed barely inhibition on CYP3A4 and CYP2D6. The excretion study manifested that IMB-SD62 was mainly eliminated by fecal excretion in rats. We concluded that based on these pharmaceutical properties, IMB-SD62 has the potential to be developed into new TB drug., (Copyright © 2018. Published by Elsevier Ltd.)

PF-06456384 is an extremely potent and selective blocker of the Na v 1.7 sodium channel designed as a potential intravenous (i.v.) analgesic targeting high potency and rapid clearance to minimize the potential for residual effects following the end of infusion. In our previous experience targeting oral molecules, the requirement to obtain potent, Na v 1.7 selective molecules led to a focus on acidic, amphipilic compounds cleared primarily by organic anion-transporting polypeptide mediated hepatic uptake and subsequent biliary excretion. However, the physicochemical properties of the i.v. lead matter were substantially different, moving from acidic, amphiphilic chemical space to zwitterions as well as substantially increasing molecular weight. This report describes the continued relevance of organic anion-transporting polypeptide driven hepatic uptake in this physicochemical space and highlights an apparent impact of the formulation excipient Solutol on the clearance and distribution of PF-06456384., (© 2018 John Wiley & Sons, Ltd.)

Targeted therapy of hepatocellular carcinoma (HCC) is essential for improved therapies. Therefore, identification of key targets specifically to HCC is an urgent requirement. Herein, an iTRAQ quantitative proteomic approach was employed to identify differentially expressed proteins in HCC tumor tissues. Of the upregulated tumor-related proteins, minichromosome maintenance 2 (MCM2), a DNA replication licensing factor, was one of the most significantly altered proteins, and its overexpression was confirmed using tissue microarray. Clinicopathological analysis of multiple cohorts of HCC patients indicated that overexpression of MCM2 was validated in 89.8% tumor tissues and strongly correlated with clinical stage. Furthermore, siRNA-mediated repression of MCM2 expression resulted in significant suppression of the HepG2 cell cycle and proliferation through the cyclin D-dependent kinases (CDKs) 2/7 pathway. Finally, the first small molecule-based MCM2-targeted NIR-II probe CH1055-MCM2 was concisely generated and subsequently evaluated in mice bearing HepG2 xenografts. The excellent imaging properties such as good tumor uptake and high tumor contrast and specificity were achieved in the small animal models. This analytical strategy can determine novel accessible targets of HCC useful for imaging and therapy.

Xanomeline (3-(Hexyloxy)-4-(1-methyl-1,2,5,6-tetrahydropyridin-3-yl)-1,2,5-thiadiazole) is a muscarinic agonist that is considered to be functionally selective for the M 1 /M 4 receptor subtypes. Part of xanomeline binding is resistant to washing. Wash-resistant xanomeline activates muscarinic receptors persistently, except for the M 5 subtype. Mutation of leucine 6.46 to isoleucine at M 1 or M 4 receptors abolished persistent activation by wash-resistant xanomeline. Reciprocal mutation of isoleucine 6.46 to leucine at the M 5 receptor made it sensitive to activation by wash-resistant xanomeline. Lowering of membrane cholesterol made M 1 and M 4 mutants and M 5 wild type receptors sensitive to activation by wash-resistant xanomeline. Molecular docking revealed a cholesterol binding site in the groove between transmembrane helices 6 and 7. Molecular dynamics showed that interaction of cholesterol with this binding site attenuates receptor activation. We hypothesize that differences in cholesterol binding to this site between muscarinic receptor subtypes may constitute the basis for xanomeline apparent functional selectivity and may have notable therapeutic implications. Differences in receptor-membrane interactions, rather than in agonist-receptor interactions, represent a novel possibility to achieve pharmacological selectivity. Our findings may be applicable to other G protein coupled receptors., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The plant activator acibenzolar-S-methyl (BTH) undergoes phototransformation when exposed to solar radiation. Here we investigated the changes in its elicitation properties on BY-2 tobacco cells at different stages of the photochemical reaction. Both pure BTH and formulated BTH were irradiated in controlled conditions to achieve different extents of conversion. Both pure BTH (900 μM) and Bion ® (0.4 g.L -1 ) induced BY-2 cell death, but BTH photoconverted to an extent of 25 ± 3% lowered the cell death rate. A kinetic study of β-1,3-glucanase and chitinase activities was conducted on BY-2 extracellular medium. Exposure of tobacco cells to either pure BTH or Bion ® resulted in a significant increase in the activities of both defense enzymes, which peaked 48 h after the treatment. The pathogenesis-related (PR) protein activities were quantified 48 h after elicitation for a range of phototransformed BTH solutions. The enzyme activities were reduced when BY-2 cells were treated with solutions in which BTH conversion was 22 ± 3%, 42 ± 3% and 100 ± 3%, but were not affected by the solution in which BTH was phototransformed at 60%, suggesting that some of the secondary photoproducts also exhibit eliciting properties. Solar irradiation of BTH thus impairs its elicitation properties, but this impairment depends strongly on the extent of phototransformation., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Diverse neurodegenerative disorders are characterized by deposition of tau fibrils composed of conformers (i.e. strains) unique to each illness. The development of tau imaging agents has enabled visualization of tau lesions in tauopathy patients, but the modes of their binding to different tau strains remain elusive. Here we compared binding of tau positron emission tomography ligands, PBB3 and AV-1451, by fluorescence, autoradiography and homogenate binding assays with homologous and heterologous blockades using tauopathy brain samples. Fluorescence microscopy demonstrated intense labelling of non-ghost and ghost tangles with PBB3 and AV-1451, while dystrophic neurites were more clearly detected by PBB3 in brains of Alzheimer's disease and diffuse neurofibrillary tangles with calcification, characterized by accumulation of all six tau isoforms. Correspondingly, partially distinct distributions of autoradiographic labelling of Alzheimer's disease slices with 11C-PBB3 and 18F-AV-1451 were noted. Neuronal and glial tau lesions comprised of 4-repeat isoforms in brains of progressive supranuclear palsy, corticobasal degeneration and familial tauopathy due to N279K tau mutation and 3-repeat isoforms in brains of Pick's disease and familial tauopathy due to G272V tau mutation were sensitively detected by PBB3 fluorescence in contrast to very weak AV-1451 signals. This was in line with moderate 11C-PBB3 versus faint 18F-AV-1451 autoradiographic labelling of these tissues. Radioligand binding to brain homogenates revealed multiple binding components with differential affinities for 11C-PBB3 and 18F-AV-1451, and higher availability of binding sites on progressive supranuclear palsy tau deposits for 11C-PBB3 than 18F-AV-1451. Our data indicate distinct selectivity of PBB3 compared to AV-1451 for diverse tau fibril strains. This highlights the more robust ability of PBB3 to capture wide-range tau pathologies., (© The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Purpose: This first-in-human report examined the recommended Phase 2 dose and schedule of litronesib, a selective allosteric kinesin Eg5 inhibitor., Methods: Two concurrent dose-escalation studies investigated litronesib across the dose range of 0.125-16 mg/m 2 /day, evaluating the following schedules of administration on a 21-day cycle: Days 1, 2, 3; Days 1, 5, 9; Days 1, 8; Days 1, 5; or Days 1, 4, with or without pegfilgrastim. Best overall response was defined per Response Evaluation Criteria in Solid Tumors (RECIST Version 1.0). Pharmacokinetic (PK) evaluations were performed. Exploratory PK/pharmacodynamic analyses investigated the relationship between litronesib plasma exposure and changes in phosphohistone H3 (pHH3) levels., Results: One hundred and seventeen patients with advanced malignancies were enrolled. Neutropenia was the primary dose-limiting toxicity. Prophylactic pegfilgrastim reduced neutropenia frequency and severity, allowing administration of higher litronesib doses, but increases in the incidences of mucositis and stomatitis were observed. Among 86 response-evaluable patients, 2 patients (2%) achieved partial response, both on the Days 1, 2, 3 regimen (5 and 6 mg/m 2 /day with pegfilgrastim), and 17 patients (20%) maintained stable disease for ≥6 cycles. Dose-dependent increases in litronesib plasma exposure were observed, with minor intra- and inter-cycle accumulation, along with exposure-dependent increases in pHH3 expression in tumor and skin biopsies., Conclusions: On the basis of the results of these studies, two regimens were selected for Phase 2 exploration: 6 mg/m 2 /day on Days 1, 2, 3 plus pegfilgrastim and 8 mg/m 2 /day on Days 1, 5, 9 plus pegfilgrastim, both on a 21-day cycle.

Context: Women's health disorders are commonly treated by agents that suppress the hypothalamic-pituitary-gonadal axis. NK3 receptor antagonism modulates this axis with distinct pharmacology compared to existing therapies., Objective: The study aim was to evaluate safety, pharmacokinetics, and pharmacodynamics on gonadotropins and sex hormones after single- and multiple-dose administration of an NK3R antagonist to healthy men and women., Design and Setting: This was a first-in-human, double-blind, placebo-controlled, combined single and multiple ascending dose trial., Participants: Forty-one men and 24 regularly cycling women participated in the study., Intervention(s): In part 1 of the study, men received single oral doses of 3-180 mg or placebo. In part 2, men received placebo or 20, 60, or 180 mg each day for 10 days. In part 3, women received placebo or 20, 60, or 180 mg each day for 21 days, where dosing was initiated on day 3 ± 2 after menses., Main Outcome Measure(s): Safety, tolerability, pharmacokinetics, and pharmacodynamics on circulating levels of LH, FSH, testosterone, estradiol, and progesterone, in addition to physiological biomarkers of endometrial thickening, follicle growth, and the duration of the menstrual cycle were evaluated., Results: ESN364 was well-tolerated and rapidly bioavailable with linear pharmacokinetics and no drug accumulation with repeated, daily oral administration. Drug treatment dose-dependently decreased basal LH, but not FSH, and consequently decreased estradiol and progesterone (in women) as well as testosterone (in men). The hormonal changes in women corresponded to delayed ovulation, decreased endometrial thickening, impeded follicular maturation, and prolongation of the menstrual cycle. Drug effects were rapidly reversible., Conclusions: Oral administration of the NK3R antagonist, ESN364, suppressed the hypothalamic-pituitary-gonadal axis in healthy volunteers by selective modulation of gonadotropin secretion, leading to a restrained decrease in ovarian hormone levels in women. These results suggest that ESN364 may offer therapeutic benefit in the treatment of women's health disorders with a mitigated risk of menopausal-like adverse events.

An empirical approach to improve the microsomal stability and CYP inhibition profile of lead compounds 1a and 1b led to the identification of 5 (BMS-341) as a dissociated glucocorticoid receptor modulator. Compound 5 showed significant improvements in pharmacokinetic properties and, unlike compounds 1a-b, displayed a linear, dose-dependent pharmacokinetic profile in rats. When tested in a chronic model of adjuvant-induced arthritis in rat, the ED50 of 5 (0.9 mg/kg) was superior to that of both 1a and 1b (8 and 17 mg/kg, respectively).

Kinesin spindle protein (KSP) is a mitotic kinesin that is expressed only in proliferating cells and plays a key role in spindle pole separation, formation of a bipolar mitotic spindle, as well as centrosome separation and maturation. Inhibition of KSP has the potential to provide anti-tumor activity while avoiding peripheral neuropathy associated with some microtubule-targeted drugs. Based on MK-0731 and related heterocyclic compounds targeting the KSP monastrol binding site, structurally constrained spiro-cyclic KSP inhibitors were designed. In particular, rapid evaluation and optimization of the novel spiro 1,3,4-thiadiazolines resulted in a series of potent KSP inhibitors demonstrating mechanism based activities in cells, including induction of the mitotic marker phospho-histone H3 and induction of monaster spindle formation. Further optimization of the pharmacokinetic (PK) properties afforded MK-8267 as a potent, orally bioavailable and brain penetrant KSP inhibitor which showed anti-tumor activity in preclinical xenograft models., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Purpose Filanesib (ARRY-520) is a highly selective, targeted inhibitor of kinesin spindle protein (KSP) inhibitor that induces mitotic arrest and subsequent tumor cell death. This first-in-human Phase 1 study evaluated dose-limiting toxicities (DLTs) and determined a maximum tolerated dose (MTD) for filanesib administered as a 1-h intravenous infusion on 2 treatment schedules in patients with advanced solid tumors. The pharmacokinetics (PK), pharmacodynamics and preliminary efficacy of filanesib were also evaluated. Methods Filanesib was administered on Day 1 of each 3-week cycle (Initial Schedule) or Days 1 and 2 of each 2-week cycle (Alternate Schedule). A standard 3 + 3 dose-escalation design was employed. An expansion cohort was conducted at the MTD of the Initial Schedule. Filanesib PK was evaluated in plasma (both schedules) and urine (Initial Schedule only). Monopolar spindle formation was evaluated in biopsies taken from patients in the expansion cohort. Results Forty-one patients received filanesib. The MTD was equivalent for both the Initial and Alternate Schedules (2.50 mg/m(2)/cycle). The prevalence of neutropenia as a DLT for both schedules necessitated adding prophylactic filgrastim to another dose escalation on the Alternate Schedule (highest tolerated dose 3.20 mg/m(2)/cycle). Neurotoxicity related to filanesib was not observed. Dose-proportional increases in filanesib exposure were observed. The half-life for filanesib was ~70 h. Monopolar spindles in patient biopsy samples indicated KSP inhibition. Stable disease was the best tumor response observed in 18 % (7/39) of evaluable patients. Conclusion Filanesib provided exposures with acceptable tolerability and evidence of target-specific pharmacodynamic effects.

ARRY-403 is a glucokinase activator developed for the treatment of diabetes. Less than dose-proportional exposure was observed during single ascending dose studies with ARRY-403. A physiologically based pharmacokinetic (PBPK) model for ARRY-403 was developed through integration of in vitro physicochemical data with precipitation time estimations based on results from the single ascending dose studies; PBPK modeling indicated that the primary cause of the less than dose-proportional exposure was dose-limited absorption because of pH-dependent solubility. The impact of dose, particle size, and fasted or fed state on ARRY-403 exposure was examined through sensitivity analyses and used to refine the PBPK model. On the basis of the marked pH-dependent solubility of ARRY-403, the refined PBPK model was used to simulate the effects of acid-reducing agents (ARAs) on ARRY-403 exposure, as these agents are widely available and could be coadministered with ARRY-403. The simulations indicated that a clinical study with an ARA was warranted; in a clinical study, famotidine had a marked effect on ARRY-403 exposure. This approach, based on the "predict, learn, and confirm" paradigm, demonstrates the utility of integrating physicochemical properties, in vitro experiments, and clinical results using PBPK to inform formulation development and to guide clinical study design., (© 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.)

Objective: Treatment of myocardial infarction within the first 1 to 2 hours with a thrombolytic agent, percutaneous coronary intervention, or an αIIbβ3 antagonist decreases mortality and the later development of heart failure. We previously reported on a novel small molecule αIIbβ3 antagonist, RUC-2, that has a unique mechanism of action. We have now developed a more potent and more soluble congener of RUC-2, RUC-4, designed to be easily administered intramuscularly by autoinjector to facilitate its use in the prehospital setting. Here, we report the properties of RUC-4 and the antiplatelet and antithrombotic effects of RUC-2 and RUC-4 in animal models., Approach and Results: RUC-4 was ≈ 20% more potent than RUC-2 in inhibiting human ADP-induced platelet aggregation and much more soluble in aqueous solutions (60-80 mg/mL). It shared RUC-2's specificity for αIIbβ3 versus αVβ3, did not prime the receptor to bind fibrinogen, or induce changes in β3 identified by a conformation-specific monoclonal antibody. Both RUC-2 and RUC-4 prevented FeCl3-induced thrombotic occlusion of the carotid artery in mice and decreased microvascular thrombi in response to laser injury produced by human platelets infused into transgenic mice containing a mutated von Willebrand factor that reacts with human but not mouse platelets. Intramuscular injection of RUC-4 in nonhuman primates at 1.9 and 3.85 mg/kg led to complete inhibition of platelet aggregation within 15 minutes, with dose-dependent return of platelet aggregation after 4.5 to 24 hours., Conclusions: RUC-4 has favorable biochemical, pharmacokinetic, pharmacodynamic, antithrombotic, and solubility properties as a prehospital therapy of myocardial infarction, but the possibility of increased bleeding with therapeutic doses remains to be evaluated., (© 2014 American Heart Association, Inc.)

A series of novel pleuromutilin derivatives possessing thiadiazole moieties were synthesized via acylation reactions under mild conditions. The in vitro antibacterial activities of the derivatives against methicillin-resistant Staphylococcus aureus, methicillin-resistant Staphylococcus epidermidis, Escherichia coli, and Streptococcus agalactiae were tested by the agar dilution method and Oxford cup assay. The majority of the tested compounds displayed moderate antibacterial activities. Importantly, the three compounds with amino or tertiary amine groups in their side chains, 11, 13b, and 15c, were the most active antibacterial agents. Docking experiments carried out on the peptidyl transferase center (PTC) of 23S rRNA proved that there is a reasonable direct correlation between the binding free energy (ΔGb, kcal/mol) and the antibacterial activity. Moreover, the pharmacokinetic profiles of 11 and 15c in rat were characterized by moderate clearance and oral bioavailability.

Purpose: Eg5, a mitotic motor kinesin protein, plays an essential role in bipolar spindle formation in the M phase of the cell cycle. LY2523355 (litronesib) is an allosteric inhibitor of Eg5. This phase 1 and dose-finding study aimed to assess the safety, pharmacokinetics (PK), recommended dose for further studies, and preliminary efficacy in Japanese patients with advanced solid tumors., Methods: LY2523355 was given on days 1, 2, and 3 every 3 weeks at one of three dose levels: 2, 4, and 5 mg/m²/day. Toxicity was assessed according to NCI-CTCAE version 4.0, and tumor response according to RECIST version 1.1. granulocyte colony-stimulating factor (G-CSF) was used only for grade 4 neutropenia or grade 3 febrile neutropenia., Results: Twelve patients were treated at doses of 2 (n = 3), 4 (n = 3), and 5 (n = 6) mg/m²/day. Most frequent treatment-related adverse events were neutropenia and leukopenia (100 %). Grade 4 neutropenia was observed in 83 %, but all recovered to above 500 neutrophils/μl within 7 days. All patients at 4 and 5 mg/m²/day required G-CSF support. No dose-limiting toxicities were reported up to 5 mg/m²/day. In PK analysis, LY2523355 exposure increased in a dose-dependent manner. The PK parameters for LY2523355 were similar to those observed in Western populations. No objective tumor responses were observed., Conclusions: The recommended dose of LY2523355 with therapeutic G-CSF use for further studies was determined to be 5 mg/m²/day in Japanese patients with advanced solid tumors.

Background and Purpose: Aquaporin 4 (AQP-4) is the most abundant aquaporin isoform in the brain. Alterations in its expression and distribution have been correlated with the progression of several clinical disorders; however, the specific roles of AQP-4 in those disorders are not well understood. Visualizing AQP-4 in vivo is expected to provide fresh insights into its roles in disease pathology, as well as aiding the clinical assessment of those disorders., Methods: We developed a 11C-labeled analogue of the AQP-4 ligand TGN-020 (2-nicotinamido-1,3,4-thiadiazole) suitable for in vivo positron emission tomography (PET) imaging., Results: In the present study, we report the first PET images of AQP-4 in the human brain. The results unequivocally demonstrated a specific distribution pattern for AQP-4 within the brain, namely, the subpial and perivascular endfeet of astrocytes. The choroid plexus, where both AQP-4 and AQP-1 are expressed, also showed substantial uptake of the ligand., Conclusions: Based on these initial results, we believe [11C]TGN-020 PET will be valuable in determining the role of AQP-4 in disease progression, and for the clinical assessment of water homeostasis under various settings., (Copyright © 2012 by the American Society of Neuroimaging.)

Background: ARRY-520 selectively inhibits the mitotic kinesin spindle protein (KSP), which leads to abnormal monopolar spindle formation and apoptosis., Methods: A phase 1 trial was conducted to establish the safety and the maximum tolerated dose (MTD) of ARRY-520 given as a 1-hour infusion in either a single dose or on a day 1, 3, and 5 divided-dose schedule per cycle in patients with advanced or refractory myeloid leukemias. Additional objectives were to characterize pharmacokinetics, assess preliminary clinical activity, and explore biomarkers of KSP inhibition with ARRY-520. A total of 36 patients with acute myelogenous leukemia (n = 34) or myelodysplastic syndromes (n = 2) with a median age of 66 years (range, 21-88 years) were enrolled: 15 in the single-dose schedule (dose levels: 2.5, 3.75, 4.5, and 5.6 mg/m(2)) and 21 in the divided-dose schedule (dose levels: 0.8, 1.2, 1.5, and 1.8 mg/m(2)/day)., Results: The MTD was 4.5 mg/m(2) total dose per cycle for both dose schedules. Dose-limiting toxicities included mucositis, exfoliative rash, hand-foot syndrome, and hyperbilirubinemia. Grades 3 or 4 reversible drug-related myelosuppression were observed in 33 of 36 patients. Plasma pharmacokinetic analyses revealed low clearance of ARRY-520 (~3 L/hour), a volume of distribution of ~450 L, and a median terminal half-life of >90 hours. Monopolar spindles were observed in blood mononuclear cells, through use of 4',6-diamidino-2-phenylindole nucleic acid stain and antitubulin antibodies., Conclusions: On the basis of the relative lack of clinical activity, further development of ARRY-520 as an antileukemic agent was halted. (Clinicaltrials.gov identifier NCT00637052)., (Copyright © 2011 American Cancer Society.)

A series of compounds were designed and synthesized as antagonists of cIAP1/2, ML-IAP, and XIAP based on the N-terminus, AVPI, of mature Smac. Compound 1 (GDC-0152) has the best profile of these compounds; it binds to the XIAP BIR3 domain, the BIR domain of ML-IAP, and the BIR3 domains of cIAP1 and cIAP2 with K(i) values of 28, 14, 17, and 43 nM, respectively. These compounds promote degradation of cIAP1, induce activation of caspase-3/7, and lead to decreased viability of breast cancer cells without affecting normal mammary epithelial cells. Compound 1 inhibits tumor growth when dosed orally in the MDA-MB-231 breast cancer xenograft model. Compound 1 was advanced to human clinical trials, and it exhibited linear pharmacokinetics over the dose range (0.049 to 1.48 mg/kg) tested. Mean plasma clearance in humans was 9 ± 3 mL/min/kg, and the volume of distribution was 0.6 ± 0.2 L/kg.

A novel series of 1,2,4-thiadiazole compounds was discovered as selective S1P(1) agonists. The extensive structure-activity relationship studies for these analogues were reported. Among them, 17g was identified to show high in vitro potency with reasonable free unbound fraction in plasma (F(u) > 0.5%), good brain penetration (BBR > 0.5), and desirable pharmacokinetic properties in mouse and rat. Oral administration of 1 mg/kg 17g resulted in significant peripheral lymphocytes reduction at 4 h after dose and rapid lymphocytes recovery at 24 h. 17g showed a transient lymphopenia profile in the repeated dose study in mouse. In addition, 17g also demonstrated efficacy comparable to that of FTY720 (1) in the mouse EAE model of MS.

A structure-activity relationship study was undertaken to address the lack of oral exposure of the H3 antagonist 1, which incorporated an arylketone. Among a number of sub-series, the 4H-pyrido[1,2-a]pyrimidin-4-one analog 21 showed an improved PK profile in rat and mouse and was active in an obesity model. The pyrimidin-4-one proved to be a novel and useful ketone bioisostere., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Spinal muscular atrophy (SMA) is an autosomal recessive disorder affecting the expression or function of survival motor neuron protein (SMN) due to the homozygous deletion or rare point mutations in the survival motor neuron gene 1 (SMN1). The human genome includes a second nearly identical gene called SMN2 that is retained in SMA. SMN2 transcripts undergo alternative splicing with reduced levels of SMN. Up-regulation of SMN2 expression, modification of its splicing, or inhibition of proteolysis of the truncated protein derived from SMN2 have been discussed as potential therapeutic strategies for SMA. In this manuscript, we detail the discovery of a series of arylpiperidines as novel modulators of SMN protein. Systematic hit-to-lead efforts significantly improved potency and efficacy of the series in the primary and orthogonal assays. Structure-property relationships including microsomal stability, cell permeability, and in vivo pharmacokinetics (PK) studies were also investigated. We anticipate that a lead candidate chosen from this series may serve as a useful probe for exploring the therapeutic benefits of SMN protein up-regulation in SMA animal models and a starting point for clinical development.

A series of 2-piperidinopiperidine-5-arylthiadiazoles was synthesized and subjected to a structure-activity relationship (SAR) investigation. The potency of this series was improved to the single digit nanomolar range. The key analogs were shown to be free of P450 issues, and they also maintained good ex vivo activity and brain penetration., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Novel indole-3-heterocycles were designed and synthesized and found to be potent CB1 receptor agonists. Starting from a microsomally unstable lead 1, a bioisostere approach replacing a piperazine amide was undertaken. This was found to be a good strategy for improving stability both in vitro and in vivo. This led to the discovery of 24, which had an increased duration of action in the mouse tail flick test in comparison to the lead 1., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Structure-activity relationship studies in a series of diarylpyrazolyl thiadiazoles identified cannabinoid-1 receptor antagonists with excellent potency and selectivity. Based on its exceptional in vivo efficacy in animal models and its favorable pharmacokinetic and toxicological profiles, 2-(4-((1H-1,2,4-triazol-1-yl)methyl)-5-(4-bromophenyl)-1-(2-chlorophenyl)-1H-pyrazol-3-yl)-5-tert-butyl-1,3,4-thiadiazole (GCC2680) was selected as a preclinical candidate for the treatment of obesity., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Structural modification of a virtual screening hit led to the identification of a new series of 4-[3-aryl-2,2-dioxido-2,1,3-benzothiadiazol-1(3H)-yl]-1-(methylamino)butan-2-ols which are potent and selective inhibitors of the norepinephrine transporter over both the serotonin and dopamine transporters. One representative compound S-17b (WYE-103231) had low nanomolar hNET potency (IC(50) = 1.2 nM) and excellent selectivity for hNET over hSERT (>1600-fold) and hDAT (>600-fold). S-17b additionally had a good pharmacokinetic profile and demonstrated oral efficacy in rat models of ovariectomized-induced thermoregulatory dysfunction and morphine dependent flush as well as the hot plate and spinal nerve ligation (SNL) models of acute and neuropathic pain.

A series of 2-aminothiadiazole of inhibitors of AKT1 is described. SAR relationships are discussed, along with selectivity for protein kinase A (PKA) and cyclin-dependent kinase 2 (CDK2). Moderate selectivity observed in several compounds for AKT1 versus PKA is rationalized by X-ray crystallographic analysis. Key compounds showed activity in cellular assays measuring phosphorylation of two AKT substrates, PRAS40 and FKHRL1. Compound 30 was advanced to a mouse liver PD assay, where it showed dose-dependent inhibition of AKT activity, as measured by the inhibition of phospho-PRAS40., (Copyright 2010 Elsevier Ltd. All rights reserved.)

Phosphatidylinositol 3-kinase/phosphatidylinositide-dependent protein kinase 1 (PDPK1)/Akt signaling plays a critical role in activating proliferation and survival pathways within cancer cells. We report the molecular pharmacology and antitumor activity of PHT-427, a compound designed to bind to the pleckstrin homology (PH) binding domain of signaling molecules important in cancer. Although originally designed to bind the PH domain of Akt, we now report that PHT-427 also binds to the PH domain of PDPK1. A series of PHT-427 analogues with variable C-4 to C-16 alkyl chain length were synthesized and tested. PHT-427 itself (C-12 chain) bound with the highest affinity to the PH domains of both PDPK1 and Akt. PHT-427 inhibited Akt and PDPK1 signaling and their downstream targets in sensitive but not resistant cells and tumor xenografts. When given orally, PHT-427 inhibited the growth of human tumor xenografts in immunodeficient mice, with up to 80% inhibition in the most sensitive tumors, and showed greater activity than analogues with C4, C6, or C8 alkyl chains. Inhibition of PDPK1 was more closely correlated to antitumor activity than Akt inhibition. Tumors with PIK3CA mutation were the most sensitive, and K-Ras mutant tumors were the least sensitive. Combination studies showed that PHT-427 has greater than additive antitumor activity with paclitaxel in breast cancer and with erlotinib in non-small cell lung cancer. When given >5 days, PHT-427 caused no weight loss or change in blood chemistry. Thus, we report a novel PH domain binding inhibitor of PDPK1/Akt signaling with significant in vivo antitumor activity and minimal toxicity.

A series of stearoyl-CoA desaturase 1 (SCD1) inhibitors were developed. Investigations of enzyme potency and metabolism led to the identification of the thiadiazole-pyridazine derivative MF-438 as a potent SCD1 inhibitor. MF-438 exhibits good pharmacokinetics and metabolic stability, thereby serving as a valuable tool for further understanding the role of SCD inhibition in biological and pharmacological models of diseases related to metabolic disorders., (Copyright 2009 Elsevier Ltd. All rights reserved.)

Background: Since the cannabinoid receptor 1 (CB1) antagonist SR141716 (rimonabant) was previously reported to modulate food intake, CB1 antagonism has been considered as a new therapeutic target for the treatment of obesity., Discussion: In the present study, biarylpyrazole analogues based on a sulfur-containing pyrazole core coupled with 1,3,4-oxadiazole and 1,3,4-thiadiazole were synthesized and assayed for rat CB1 receptor binding affinity., Results: The structure-activity relationship studies to optimize pyrazole substituents as well as 1,3,4-oxadiazole or 1,3,4-thiadiazole rings led to four novel CB1 antagonists with IC(50) values of approximately 1 nM for the rat CB1 receptor binding. Among these derivatives, we identified trifluoromethylcyclobutyl analogues 19e and 19l as promising precandidates for the development as anti-obesity agents.

Previous studies suggest that selective antagonists of specific subtypes of muscarinic acetylcholine receptors (mAChRs) may provide a novel approach for the treatment of certain central nervous system (CNS) disorders, including epileptic disorders, Parkinson's disease, and dystonia. Unfortunately, previously reported antagonists are not highly selective for specific mAChR subtypes, making it difficult to definitively establish the functional roles and therapeutic potential for individual subtypes of this receptor subfamily. The M(1) mAChR is of particular interest as a potential target for treatment of CNS disorders. We now report the discovery of a novel selective antagonist of M(1) mAChRs, termed VU0255035 [N-(3-oxo-3-(4-(pyridine-4-yl)piperazin-1-yl)propyl)-benzo[c][1,2,5]thiadiazole-4 sulfonamide]. Equilibrium radioligand binding and functional studies demonstrate a greater than 75-fold selectivity of VU0255035 for M(1) mAChRs relative to M(2)-M(5). Molecular pharmacology and mutagenesis studies indicate that VU0255035 is a competitive orthosteric antagonist of M(1) mAChRs, a surprising finding given the high level of M(1) mAChR selectivity relative to other orthosteric antagonists. Whole-cell patch-clamp recordings demonstrate that VU0255035 inhibits potentiation of N-methyl-D-aspartate receptor currents by the muscarinic agonist carbachol in hippocampal pyramidal cells. VU0255035 has excellent brain penetration in vivo and is efficacious in reducing pilocarpine-induced seizures in mice. We were surprised to find that doses of VU0255035 that reduce pilocarpine-induced seizures do not induce deficits in contextual freezing, a measure of hippocampus-dependent learning that is disrupted by nonselective mAChR antagonists. Taken together, these data suggest that selective antagonists of M(1) mAChRs do not induce the severe cognitive deficits seen with nonselective mAChR antagonists and could provide a novel approach for the treatment certain of CNS disorders.

The development of potent gamma-secretase inhibitors having substituted heterocycles attached to a benzobicyclo[4.2.1]nonane core is described. This work led to the identification of [6S,9R,11R]-2',3',4',5,5',6,7,8,9,10-decahydro-2-(5-(4-fluorophenyl)-1-methylpyrazol-3-yl)-5'-(2,2,2-trifluoroethyl)spiro[6,9-methanobenzocyclooctene-11,3'-[1,2,5]thiadiazole] 1',1'-dioxide (16), which has excellent in vitro potency (0.06 nM) and which reduced amyloid-beta in APP-YAC mice with an ED(50) of 1 mg/kg (po). 16 had a good pharmacokinetic profile in three preclinical species.

Background/aims: Xanomeline has been shown to bind in a unique manner at M1 and M3 muscarinic receptors, with interactions at both the orthosteric site and an allosteric site. We have previously shown that brief exposure of Chinese hamster ovary cells that express the M3 receptor to xanomeline followed by removal of free agonist results in a delayed decrease in radioligand binding and receptor response to agonists. In the current study, we were interested in determining the mechanisms of this effect., Methods: Cells were treated with carbachol, pilocarpine or xanomeline for 1 h followed by washing and either used immediately or after waiting for 23 h. Control groups included cells that were not exposed to agonists and cells that were treated with agonists for 24 h. Radioligand binding and functional assays were conducted to determine the effects of agonist treatments., Results: The above treatment protocol with xanomeline resulted in similar effects of the binding of [(3)H]NMS and [(3)H]QNB. When receptor function is blocked using a variety of methods, the long-term effects of xanomeline binding were absent., Conclusion: Our data indicate that xanomeline wash-resistant binding at the receptor allosteric site leads to receptor downregulation and that receptor activation is necessary for these effects., (Copyright 2009 S. Karger AG, Basel.)

A series of thiadiazolopiperazinyl aryl urea fatty acid amide hydrolase (FAAH) inhibitors is described. The molecules were found to inhibit the enzyme by acting as mechanism-based substrates, forming a covalent bond with Ser241. SAR and PK properties are presented.

Introduction: The only radiotracer available for the selective imaging of muscarinic M2 receptors in vivo is 3-(3-(3-[18F]fluoropropyl)thio)-1,2,5-thiadiazol-4-yl)-1,2,5,6-tetrahydro-1-methylpyridine) ([18F]FP-TZTP). We have prepared and labeled 3-(3-(3-fluoropropylthio)-1,2,5-thiadiazol-4-yl)-1,2,5,6-tetrahydro-1-methylpyridne (FP-TZTP, 3) and two other TZTP derivatives with 11C at the methylpyridine moiety to explore the potential of using 11C-labeled FP-TZTP for positron emission tomography imaging of M2 receptors and to compare the effect of small structural changes on tracer pharmacokinetics (PK) in brain and peripheral organs., Methods: 11C-radiolabeled FP-TZTP, 3-(3-propylthio)-TZTP (6) and 3,3,3-(3-(3-trifluoropropyl)-TZTP (10) were prepared, and log D, plasma protein binding (PPB), affinity constants, time-activity curves (TACs), area under the curve (AUC) for arterial plasma, distribution volumes (DV) and pharmacological blockade in baboons were compared., Results: Values for log D, PPB and affinity constants were similar for 3, 6 and 10. The fraction of parent radiotracer in the plasma was higher and the AUC lower for 10 than for 3 and 6. TACs for brain regions were similar for 3 and 6, which showed PK similar to the 18F tracer, while 10 showed slower uptake and little clearance over 90 min. DVs for 3 and 6 were similar to the 18F tracer but higher for 10. Uptake of the three tracers was significantly reduced by coinjection of unlabeled 3 and 6., Conclusion: Small structural variations on the TZTP structure greatly altered the PK in brain and behavior in blood with little change in the log D, PPB or affinity. The study suggests that 11C-radiolabeled 3 will be a suitable alternative to [18F]FP-TZTP for translational studies in humans.

Replacement of the methyl-thiazole moiety of GW501516 (a PPARdelta selective agonist) with [1,2,4]thiadiazole gave compound 21 which unexpectedly displayed submicromolar potency as a partial agonist at PPARalpha in addition to the high potency at PPARdelta. A structure-activity relationships study of 21 resulted in the identification of 40 as a potent and selective PPARalpha/delta dual agonist. Compound 40 and its close analogs represent a new series of PPARalpha/delta dual agonists. The high potency, high selectivity, significant gene induction, excellent PK profiles, low P450 inhibition or induction, and good in vivo efficacy in four animal models support 40 being selected as a pre-clinical study candidate, and may render 40 as a valuable pharmacological tool in elucidating the complex roles of PPARalpha/delta dual agonists, and the potential usage for the treatment of metabolic syndrome.

A series of novel and potent 3,4-diamino-2,5-thiadiazole-1-oxides were prepared and found to show excellent binding affinities for CXCR2 and CXCR1 receptors and excellent inhibitory activity of Gro-alpha and IL-8 mediated in vitro hPMN MPO release of CXCR2 and CXCR1 expressing cell lines. On the other hand, a closely related 3,4-diamino-2,5-thiadiazole-dioxide did not show functional activity despite its excellent binding affinities for CXCR2 and CXCR1 in membrane binding assays. A detailed SAR has been discussed in these two closely related structures.

The neutral endopeptidase inhibitor (2R)-2-[(1-{[(5-ethyl-1,3,4-thiadiazol-2-yl)amino]carbonyl}cyclopentyl)methyl]pentanoic acid 2 is metabolized to acyl glucuronide 3. Unprecedentedly, at pH 7.4, 3 does not undergo the O-acyl migration characteristic of acyl glucuronides but rapid, eliminative cyclization (t1/2 at 37 degrees C, 10.2 min) to glutarimide 4. Glucuronide 3 was synthesized efficiently via acylation of benzylglucuronate with N-benzyloxymethyl-protected 2. Glucuronide and imide reacted rapidly in aqueous solution, pH 7.4, with amino acids and glutathione to form stable amides and unstable thioesters. Imide 4 acylated eight lysine Nepsilon-amino groups of human serum albumin. Rapid cyclization of 3 was attributed to attack on the ester linkage by an unusually nucleophilic glutaramide NH (pKa in 2 = 9.76). N-propyl 3 was refractory to acyl migration and cyclization. This suggested a synthetic strategy for preparing analogues of 2 that form chemically stable acyl glucuronides.

Cardiovascular disease is the most common cause of morbidity and mortality in developed nations. To effectively target dyslipidemia to reduce the risk of cardiovascular disease, it may be beneficial to activate the peroxisome proliferator-activated receptors (PPARs) PPARalpha and PPARdelta simultaneously through a single molecule. Replacement of the methylthiazole of 5 (the PPARdelta selective agonist) with [1,2,4]thiadiazole gave compound 13, which unexpectedly displayed submicromolar potency as a partial agonist at PPARalpha in addition to the high potency at PPARdelta. Optimization of 13 led to the identification of 24 as a potent and selective PPARalpha/delta dual agonist. Compound 24 and its close analogs represent a new series of PPARalpha/delta dual agonists. The high potency, significant gene induction, excellent PK profiles, and good in vivo efficacies in three animal models may render compound 24 as a valuable pharmacological tool in elucidating the complex roles of PPARalpha/delta dual agonists and as a potential treatment of the metabolic syndrome.