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OSE-127 is a humanized mAb targeting the IL-7Rα-chain (CD127), under development for inflammatory and autoimmune disease treatment. It is a strict antagonist of the IL-7R pathway, is not internalized by target cells, and is noncytotoxic. In this work, a first-in-human, phase I, randomized, double-blind, placebo-controlled, single-center study was carried out to determine the safety, pharmacokinetics, pharmacodynamics, and immunogenicity of OSE-127 administration. Sixty-three healthy subjects were randomly assigned to nine groups: six single ascending dose groups with i.v. administration (0.002–10 mg/kg), a single s.c. treatment group (1 mg/kg), and two double i.v. injection groups (6 or 10 mg/kg). Subjects were followed during 100 d after two i.v. infusions at 10 mg/kg. IL-7 consumption was inhibited by OSE-127 administration, as demonstrated by a decreased IL-7 pathway gene signature in peripheral blood cells and by ex vivo T lymphocyte restimulation experiments. OSE-127 was well tolerated, with no evidence of cytokine-release syndrome and no significant alteration of blood lymphocyte counts or subset populations. Altogether, the observed lack of significant lymphopenia or serious adverse events, concomitant with the dose-dependent inhibition of IL-7 consumption by target cells, highlights that OSE-127 may show clinical activity in IL-7R pathway–involved diseases.

HYPOTHESIS SENS-401 (R-azasetron besylate) is effective against severe acoustic trauma-induced hearing loss. BACKGROUND SENS-401 has calcineurin inhibiting properties and attenuates cisplatin-induced hearing loss in a rat model. Cisplatin-induced and acoustic trauma-induced hearing loss share common apoptotic pathways. METHODS The dose-response relationship of SENS-401 (6.6 mg/kg BID, 13.2 mg/kg BID, 26.4 mg/kg QD) and treatment time-window (13.2 mg/kg BID starting 24, 72, and 96 h posttrauma) versus placebo for 28 days were evaluated in a male rat model of severe acoustic trauma-induced hearing loss (120 dB SPL, 2 h) using auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAE) measures followed by cochlear outer hair cell (OHC) counting with myosin-VIIa immunolabeling. RESULTS All SENS-401 doses improved ABR threshold shift and recovery, reaching statistical significance (p

An impairment of long-term synaptic plasticity is considered as a peculiar endophenotype of distinct forms of dystonia, a common, disabling movement disorder. Among the few therapeutic options, broad-spectrum antimuscarinic drugs are utilized, aimed at counteracting abnormal striatal acetylcholine-mediated transmission, which plays a crucial role in dystonia pathophysiology. We previously demonstrated a complete loss of long-term synaptic depression (LTD) at corticostriatal synapses in rodent models of two distinct forms of isolated dystonia, resulting from mutations in the TOR1A (DYT1), and GNAL (DYT25) genes. In addition to anticholinergic agents, the aberrant excitability of striatal cholinergic cells can be modulated by group I metabotropic glutamate receptor subtypes (mGlu1 and 5). Here, we tested the efficacy of the negative allosteric modulator (NAM) of metabotropic glutamate 5 (mGlu) receptor, dipraglurant (ADX48621) on striatal LTD. We show that, whereas acute treatment failed to rescue LTD, chronic dipraglurant rescued this form of synaptic plasticity both in DYT1 mice and GNAL rats. Our analysis of the pharmacokinetic profile of dipraglurant revealed a relatively short half-life, which led us to uncover a peculiar time-course of recovery based on the timing from last dipraglurant injection. Indeed, striatal spiny projection neurons (SPNs) recorded within 2 h from last administration showed full expression of synaptic plasticity, whilst the extent of recovery progressively diminished when SPNs were recorded 4–6 h after treatment. Our findings suggest that distinct dystonia genes may share common signaling pathway dysfunction. More importantly, they indicate that dipraglurant might be a potential novel therapeutic agent for this disabling disorder.

AIM: A Phase 1 study was performed to evaluate safety, pharmacokinetics (PK) and pharmacodynamics (PD) of the selective histamine H4 receptor antagonist SENS-111, an oral small molecule. METHODS: One hundred healthy subjects were randomized in a placebo-controlled, double-blind study evaluating single-ascending doses (SAD; 100-500 mg) and multiple-ascending doses (MAD; 50-150 mg day-1 , 4 days; 200-250 mg day-1 , 7 days). Effects of SENS-111 on nystagmus and vertigo induced by modified caloric tests were measured in the MAD studies. Population PK and PK/PD models were developed using a nonlinear mixed-effects approach. RESULTS: SENS-111 was well tolerated with mild to moderate events. No sedation was reported. A maximal tolerated dose was not reached. Dose-proportional increases in concentrations were seen up to 200 mg and more than dose-proportional thereafter, with mean half-life between 24 and 56 h. The caloric test induced mild but measurable vertigo and nystagmus with large intra/inter-individual variation for all parameters. SENS-111 did not significantly impact nystagmus but significantly improved latency of vertigo appearance/disappearance, duration and European Evaluation of Vertigo questionnaire parameters vs. baseline. A two-compartment model with first-order absorption, distribution and elimination best fit the data. PK/PD indirect modelling applied to vertigo duration and latency of appearance indicated maximum activity between 100 and 500 ng ml-1 plasma concentrations, corresponding to 100 and 200 mg day-1 , which are appropriate for clinical efficacy evaluations in vestibular diseases. CONCLUSIONS: SENS-111 is a well-tolerated first-in-class H4 receptor antagonist with acceptable PK for oral daily dosing. PK/PD modelling determined plasma concentrations and doses for efficacy studies in patients with vertigo symptoms.

Positive allosteric modulation of the GABAB receptor is a promising alternative to direct activation of the receptor as a therapeutic approach for treatment of addiction, chronic pain, anxiety, epilepsy, autism, Fragile X syndrome, and psychosis. Here we describe in vitro and in vivo characterization of a novel, potent and selective GABAB positive allosteric modulator (PAM) N-(5-(4-(4-chloro-3-fluorobenzyl)-6-methoxy-3,5-dioxo-4,5-dihydro-1,2,4-triazin-2(3H)-yl)-2-fluorophenyl)acetamide (ADX71441). In vitro, Schild plot and reversibility tests at the target confirmed PAM properties of the compound. In mice and rats ADX71441 is bioavailable after oral administration and is brain penetrant. A single dose of ADX71441 had an anxiolytic-like profile in the mouse marble burying test (minimum effective dose; MED 3 mg/kg) as well as in the elevated plus maze test in mice and rats (both MED 3 mg/kg). Also, in mice, acute administration of ADX71441 reduced visceral pain-associated behaviors in the acetic acid-induced writhing test. ADX71441 dose-dependently reduced time on rotarod in rats (MED 10 mg/kg) indicative of muscle-relaxant qualities. ADX71441 reduced locomotor activity in mice (10 mg/kg) and rats (3 mg/kg) after single dose; however, following sub-chronic administration in mice, 30 mg/kg ADX71441 was associated with normal locomotor activity. While acute administration of ADX71441 reduced body temperature in rats and mice (both MED 10 mg/kg), the effect in the former was transient, rapidly returning to normal levels despite high concentrations of the compound remaining in plasma. Thus, the GABAB PAM ADX71441 represents a valid therapeutic approach for development of novel treatment of anxiety, pain and spasticity.

We tested novel positive allosteric modulators (PAMs) of the γ-aminobutyric acid receptor B (GABAB), ADX71943 and ADX71441in the monosodium iodoacetate model of chronic osteoarthritis pain in rats with the objective to delineate the role of peripheral versus central GABAB receptor populations in modulation of chronic pain. Anesthetized Sprague-Dawley rats received an injection of monosodium iodoacetate into the knee and were tested for hyperalgesia starting post-MIA day 14. Effects of compounds on ipsilateral joint compression threshold were evaluated on post-MIA day 14 (after acute treatment), as well as after repeated, daily treatment on days 21 and 28 (ADX71943 only) and were compared to those of celecoxib (30mg/kg, p.o.). The PAMs were also tested in the rat rotarod test for potential muscle-relaxant effects. Acutely, ADX71943 (1-30mg/kg, p.o.), the peripherally restricted PAM, resulted in similar increases in pain threshold across the doses on day 14, while showing reduced efficacy on day 21 and no efficacy on day 28. A clear reduction in the efficacy of celecoxib across testing was also noted in this experiment. Acutely ADX71441 (0.3-15mg/kg, p.o.), the central-peripheral PAM, resulted in over 2-fold increases in pain threshold at 15mg/kg (but not at lower doses) on day 14, while causing more modest effects on day 21. Celecoxib increased pain threshold after both acute and daily treatment, showing overall similar efficacy. Thus, early, presumably more inflammatory phase of osteoarthritis pain in more sensitive to GABAB PAMs with peripherally restricted profile, while later, presumably more neuropathic phase is more sensitive to PAMs with central-peripheral profile.

We previously reported the discovery of 4-aryl-substituted pyridones with mGlu2 PAM activity starting from the HTS hit 5. In this article, we describe a different exploration from 5 that led to the discovery of a novel subseries of phenylpiperidine-substituted pyridones. The optimization strategy involved the introduction of different spacers between the pyridone core and the phenyl ring of 5. The fine tuning of metabolism and hERG followed by differentiation of advanced leads that were identified on the basis of PK profiles and in vivo potency converged on lead compound 36 (JNJ-40411813). Full in vitro and in vivo profiles indicate that 36 displayed an optimal interplay between potency, selectivity, favorable ADMET/PK and cardiovascular safety profile, and central EEG activity. Compound 36 has been investigated in the clinic for schizophrenia and anxious depression disorders.

Previous work has suggested that activation of mGlu5 receptor augments NMDA receptor function and thereby may constitute a rational approach addressing glutamate hypofunction in schizophrenia and a target for novel antipsychotic drug development. Here, we report the in vitro activity, in vivo efficacy and safety profile of 5PAM523 (4-Fluorophenyl){(2R,5S)-5-[5-(5-fluoropyridin-2-yl)-1,2,4-oxadiazol-3-yl]-2-methylpiperidin-1-yl}methanone), a structurally novel positive allosteric modulator selective of mGlu5. In cells expressing human mGlu5 receptor, 5PAM523 potentiated threshold responses to glutamate in fluorometric calcium assays, but does not have any intrinsic agonist activity. 5PAM523 acts as an allosteric modulator as suggested by the binding studies showing that 5PAM523 did not displace the binding of the orthosteric ligand quisqualic acid, but did partially compete with the negative allosteric modulator, MPyEP. In vivo, 5PAM523 reversed amphetamine-induced locomotor activity in rats. Therefore, both the in vitro and in vivo data demonstrate that 5PAM523 acts as a selective mGlu5 PAM and exhibits anti-psychotic like activity. To study the potential for adverse effects and particularly neurotoxicity, brain histopathological exams were performed in rats treated for 4 days with 5PAM523 or vehicle. The brain exam revealed moderate to severe neuronal necrosis in the rats treated with the doses of 30 and 50 mg/kg, particularly in the auditory cortex and hippocampus. To investigate whether this neurotoxicity is mechanism specific to 5PAM523, similar safety studies were carried out with three other structurally distinct selective mGlu5 PAMs. Results revealed a comparable pattern of neuronal cell death. Finally, 5PAM523 was tested in mGlu5 knock-out (KO) and wild type (WT) mice. mGlu5 WT mice treated with 5PAM523 for 4 days at 100 mg/kg presented significant neuronal death in the auditory cortex and hippocampus. Conversely, mGlu5 KO mice did not show any neuronal loss by histopathology, suggesting that enhancement of mGlu5 function is responsible for the toxicity of 5PAM523. This study reveals for the first time that augmentation of mGlu5 function with selective allosteric modulators results in neurotoxicity.

There is growing evidence that activation of metabotropic glutamate receptor 4 (mGlu4) leads to anxiolytic- and antipsychotic-like efficacy in rodent models, yet its relevance to depression-like reactivity remains unclear. Here, we present the pharmacological evaluation of ADX88178 [5-methyl-N-(4-methylpyrimidin-2-yl)-4-(1H-pyrazol-4-yl)thiazol-2-amine], a novel potent, selective, and brain-penetrant positive allosteric modulator of the mGlu4 receptor in rodent models of anxiety, obsessive compulsive disorder (OCD), fear, depression, and psychosis. ADX88178 dose-dependently reduced the number of buried marbles in the marble burying test and increased open-arm exploration in the elevated plus maze (EPM) test, indicative of anxiolytic-like efficacy. Target specificity of the effect in the EPM test was confirmed using male and female mGlu4 receptor knockout mice. In mice, ADX88178 reduced the likelihood of conditioned freezing in the acquisition phase of the fear conditioning test, yet had no carryover effect in the expression phase. Also, ADX88178 dose-dependently reduced duration of immobility in the forced swim test, indicative of antidepressant-like efficacy. ADX88178 reduced DOI (2,5-dimethoxy-4-iodoamphetamine)-mediated head twitches (albeit with no dose-dependency), and MK-801 [(5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine]–induced locomotor hyperactivity in mice, but was inactive in the conditioned avoidance response test in rats. The compound showed good specificity as it had no effect on locomotor activity in mice and rats at efficacious doses. Thus, allosteric activation of mGlu4 receptors can be a promising new therapeutic approach for treatment of anxiety, OCD, fear-related disorders, and psychosis.

BACKGROUND: Blocking metabotropic glutamate receptor type 5 (mGluR5) has been proposed as a target for levodopa-induced dyskinesias (LID) in Parkinson's disease (PD). We assessed the effect on LID of dipraglurant, a potent selective mGluR5 receptor negative allosteric modulator in the gold-standard LID macaque model. METHODS: Dipraglurant (3, 10, and 30 mg/kg, by mouth) was tested in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) macaque model of LID in a four-way crossover, single-dose, controlled study (n = 8). RESULTS: Dipraglurant inhibited dyskinesias in the LID macaque model, with best effect reached at 30 mg/kg dose with no alteration of levodopa efficacy. CONCLUSION: Acute challenges of dipraglurant were efficacious on choreic and dystonic LID in the MPTP-macaque model. Dipraglurant pharmacokinetic variables were similar to those of levodopa, suggesting that both drugs can be co-administered simultaneously in further studies.

A promising pharmacotherapy for alcohol use disorders has been positive allosteric modulators (PAMs) of the γ-aminobutyric acid receptor B (GABAB R) since GABAB R PAMs reduce ethanol drinking and self-administration in rodents.The current studies investigated a novel, selective GABAB R PAM, ADX71441, in comparison to naltrexone in a protocol of ethanol binge-like drinking, drinking-in-the-dark (DID), and in a model of long-term, excessive drinking, intermittent access to ethanol (IA).Male C57BL/6 J mice were given doses of ADX71441 (3, 10, 30 mg/kg, p.o.) before the fourth test day of repeated DID access to 20 % ethanol. Another group of mice had a history of 4 weeks of IA before ADX71441 (3, 10, 17 mg/kg, p.o.) treatment. The opioid antagonist, naltrexone (0.1, 1, 10 mg/kg, i.p.), was administered to different groups of mice in both protocols as a positive control.In both DID and IA protocols, ADX71441 showed a selective and potent reduction of ethanol drinking, but not water drinking, while naltrexone had a more modest and transient effect on reducing ethanol drinking. The long-lasting effect of ADX71441 agrees with its plasma pharmacokinetics in showing peak concentrations at 2 h followed by a slow decay lasting well beyond 8 h.These findings support previous studies demonstrating that GABAB R PAMs decrease voluntary ethanol intake without altering water intake. ADX71441 may be a worthwhile candidate for developing a treatment of alcoholism, yet its site of action in the brain and long-term pharmacological effects require further exploration.

ADX71943 is a potent and selective GABA(b) receptor positive allosteric modulator (PAM) which exhibits poor aqueous solubility at all physiologically relevant pHs. The aim of this study was to identify an adequate formulation to improve the solubility of ADX71943 to achieve a sufficiently high plasma exposure after oral administration to support the toxicology program. Considering the overall physicochemical properties and the low solubility of ADX71943 in a variety of solvents, solid dispersion, and particle size reduction have been successfully chosen as potential strategies to improve its oral bioavailability. Both technologies have proven useful in improving the in vitro dissolution profile and as a result of the solubility enhancement, higher bioavailability was obtained in vivo. As the solid dispersion gave better bioavailability (30-fold compared with the neat active pharmaceutical ingredient (API)), this formulation was selected for the toxicology study. Changing the crystalline form of ADX71943 into amorphous state by preparing a solid dispersion has greatly improved its oral bioavailability and has allowed achieving the required plasma concentration needed in toxicology studies.

The discovery and characterization of compound 48, a selective and in vivo active mGlu2 receptor positive allosteric modulator (PAM), are described. A key to the discovery was the rational exploration of the initial HTS hit 13 guided by an overlay model built with reported mGlu2 receptor PAM chemotypes. The initial weak in vitro activity of the hit 13 was quickly improved, although compounds still had suboptimal druglike properties. Subsequent modulation of the physicochemical properties resulted in compounds having a more balanced profile, combining good potency and in vivo pharmacokinetic properties. Final refinement by addressing cardiovascular safety liabilities led to the discovery of compound 48. Besides good potency, selectivity, and ADME properties, compound 48 displayed robust in vivo activity in a sleep-wake electroencephalogram (sw-EEG) assay consistent with mGlu2 receptor activation, in accordance with previous work from our laboratories.

Allosteric modulators of metabotropic glutamate receptors (mGluR) subtypes 1-8 have been shown to offer a valid way to develop small molecule non aminoacid-like therapeutics that can be administered orally and that readily cross the blood-brain barrier. Allosteric modulators of glutamatergic receptors and in particular mGluR5 have emerged as a novel and highly desirable class of compounds for the treatment of central nervous system (CNS) disorders and peripheral disorders. This article provides medicinal chemistry highlights around the chemical classes of potent and highly selective mGluR5 negative allosteric modulators (NAMs) and their therapeutic potential. In addition, it describes the medicinal chemistry approach from the discovery to the clinical candidate selection of a new series of heteroaryl-butynylpyridines targeting mGluR5. The multiparametric optimization of the initial starting point which ended in the selection of potential clinical candidates combining the best pharmacophoric features is presented. The pharmacological properties are reported and support the interest of these agents for new therapeutic approaches. Furthermore, a summary of the diverse mGluR5 Positron Emission Tomography (PET) radioligands is reported.

A series of N-propyl-5-substituted isoquinolones was identified as positive allosteric modulators (PAM) of metabotropic glutamate receptor 2 (mGluR2) via high-throughput screening (HTS). The subsequent synthesis and preliminary SAR exploration that led to the identification of compound 20 are described.

The discovery and characterization of compound 48, a selective and in vivo active mGlu2 receptor positive allosteric modulator (PAM), are described. A key to the discovery was the rational exploration of the initial HTS hit 13 guided by an overlay model built with reported mGlu2 receptor PAM chemotypes. The initial weak in vitro activity of the hit 13 was quickly improved, although compounds still had suboptimal druglike properties. Subsequent modulation of the physicochemical properties resulted in compounds having a more balanced profile, combining good potency and in vivo pharmacokinetic properties. Final refinement by addressing cardiovascular safety liabilities led to the discovery of compound 48. Besides good potency, selectivity, and ADME properties, compound 48 displayed robust in vivo activity in a sleep–wake electroencephalogram (sw-EEG) assay consistent with mGlu2 receptor activation, in accordance with previous work from our laboratories.

During a program directed at selective NK(1) receptor antagonists, we serendipitously discovered an NK(1) receptor ligand with additional affinity for the NK(3) receptor. Recognising an opportunity for a drug discovery program aiming for dual NK(1)/NK(3) receptor antagonists, we prepared a series of analogues from a novel, versatile building block. From this series emerged compounds with high and balanced affinities for the NK(1) and the NK(3) receptors. Typical representatives of this series were active in the gerbil foot tapping assay after oral administration.

We tested novel positive allosteric modulators (PAMs) of the γ-aminobutyric acid receptor B (GABA

Small molecule therapeutics for schizophrenia , Small molecule therapeutics for schizophrenia , کتابخانه مرکزی دانشگاه علوم پزشکی تهران

The inhibition of human cytochrome P450s (CYPs) is one of the most common mechanisms which can lead to drug-drug interactions. The inhibition of CYPs can be reversible (competitive or non-competitive) or irreversible. Irreversible inhibition usually derives from activation of a drug by CYPs into a reactive metabolite, which tightly binds to the enzyme active site, leading to a long lasting inactivation. This process is called "mechanism based inhibition" or "suicide inhibition". The irreversible inactivation usually implies the formation of a covalent bond between the metabolite and the enzyme, which can lead to hapten formation and can in some cases trigger an auto immune-response. For these reasons it is of utmost importance to study the mechanism of the CYP inhibition of new potential drugs as early as possible during the drug discovery process. The literature on CYPs is vast and covers numerous aspects of their biology and biochemistry, however to our knowledge there is no general and systematic review focusing on mechanism-based inhibitors; we have reviewed the literature and compiled all the available data on chemical entities, which are known to be CYP suicide inhibitors. Each compound is reported together with its chemical structure, the CYP isoform and the parameters describing the inactivation. Literature references are reported together with their PMID (PubMed ID number) to allow a fast retrieval of the papers. This review offers a quick reference to help predict liabilities of new chemical entities without carrying out extensive in vitro work, and will hopefully help in designing safer drugs.

Early onset torsion dystonia (DYT1) is an autosomal dominantly inherited disorder caused by deletion in TOR1A gene. Evidence suggests that TOR1A mutation produces dystonia through an aberrant neuronal signalling within the striatum, where D2 dopamine receptors (D2R) produce an abnormal excitatory response in cholinergic interneurons (ChIs) in different models of DYT1 dystonia. The excitability of ChIs may be modulated by group I metabotropic glutamate receptor subtypes (mGlu1 and 5). We performed electrophysiological and calcium imaging recordings from ChIs of both knock-in mice heterozygous for Δ-torsinA (Tor1a(+/Δgag) mice) and transgenic mice overexpressing human torsinA (hMT1). We demonstrate that the novel negative allosteric modulator (NAM) of metabotropic glutamate 5 (mGlu) receptor, dipraglurant (ADX48621) counteracts the abnormal membrane responses and calcium rise induced either by the D2R agonist quinpirole or by caged dopamine (NPEC-Dopamine) in both models. These inhibitory effects were mimicked by two other well-characterized mGlu5 receptor antagonists, SIB1757 and MPEP, but not by mGlu1 antagonism. D2R and mGlu5 post-receptor signalling may converge on PI3K/Akt pathway. Interestingly, we found that the abnormal D2R response was prevented by the selective PI3K inhibitor, LY294002, whereas PLC and PKC inhibitors were both ineffective. Currently, no satisfactory pharmacological treatment is available for DYT1 dystonia patients. Our data show that negative modulation of mGlu5 receptors may counteract abnormal D2R responses, normalizing cholinergic cell excitability, by modulating the PI3K/Akt post-receptor pathway, thereby representing a novel potential treatment of DYT1 dystonia.

Positive allosteric modulation of the GABA

We previously described a negative allosteric modulator (NAM) of FSHR (ADX61623) that blocked FSH-induced cAMP and progesterone production but did not block estradiol production. That FSHR NAM did not affect FSH-induced preovulatory follicle development as evidenced by the lack of an effect on the number of FSH-dependent oocytes found in the ampullae following ovulation with hCG. A goal is the development of a nonsteroidal contraceptive. Toward this end, a high-throughput screen using human FSHR identified an additional nonsteroidal small molecule (ADX68692). Although ADX68692 behaved like ADX61623 in inhibiting production of cAMP and progesterone, it also inhibited FSH-induced estradiol in an in vitro rat granulosa primary cell culture bioassay. When immature, noncycling female rats were injected subcutaneously or by oral dosing prior to exogenous FSH administration, it was found that ADX68692 decreased the number of oocytes recovered from the ampullae. The estrous cycles of mature female rats were disrupted by administration by oral gavage of 25 mg/kg and 10 mg/kg ADX68692. In the highest dose tested (25 mg/kg), 55% of animals cohabited with mature males had implantation sites compared to 33% in the 10 mg/kg group and 77% in the control group. A surprising finding was that a structural analog ADX68693, while effectively blocking progesterone production with similar efficacy as ADX68692, did not block estrogen production and despite better oral availability did not decrease the number of oocytes found in the ampullae even when used at 100 mg/kg. These data demonstrate that because of biased antagonism of the FSHR, nonsteroidal contraception requires that both arms of the FSHR steroidogenic pathway must be effectively blocked, particularly estrogen biosynthesis. Thus, a corollary to these findings is that it seems reasonable to propose that the estrogen-dependent diseases such as endometriosis may benefit from inhibition of FSH action at the ovary using the FSHR NAM approach.

We report that certain plasma proteins, at physiological concentrations, are potent inhibitors of amyloid beta-peptide (Abeta) polymerization. These proteins are also present in cerebrospinal fluid, but at low concentrations having little or no effect on Abeta. Thirteen proteins representing more than 90% of the protein content in plasma and cerebrospinal fluid were studied. Quantitatively, albumin was the most important protein, representing 60% of the total amyloid inhibitory activity, followed by alpha1-antitrypsin and immunoglobulins A and G. Albumin suppressed amyloid formation by binding to the oligomeric or polymeric Abeta, blocking a further addition of peptide. This effect was also observed when the incorporation of labeled Abeta into genuine beta-amyloid in tissue section was studied. The Abeta and the anti-diabetic drug tolbutamide apparently bind to the same site on albumin. Tolbutamide displaces Abeta from albumin, increasing its free concentration and enhancing amyloid formation. The present results suggest that several endogenous proteins are negative regulators of amyloid formation. Plasma contains at least 300 times more amyloid inhibitory activity than cerebrospinal fluid. These findings may provide one explanation as to why beta-amyloid deposits are not found in peripheral tissues but are only found in the central nervous system. Moreover, the data suggest that some drugs that display an affinity for albumin may enhance beta-amyloid formation and promote the development of Alzheimer's disease.

Parkinson’s disease (PD) is normally associated with dopamine and other catecholamines because of the profound loss of dopaminergic neurons in the substantia nigra that is the hallmark of the disease. The need for new therapies to treat symptomatic motor and non‐motor symptoms, along with motor complications such as L‐DOPA‐induced dyskinesias (LIDs), remains an important challenge in drug discovery. Significant progress has been made recently in the development of new non‐dopaminergic treatments in the last few years, and there is substantial evidence for altered glutamate neurotransmission in PD, which may be a consequence of dopamine loss. This has generated a great deal of interest in glutamate receptor modulators for the treatment of PD. The interest initially focused on ionotropic glutamate receptors (iGluRs) both for the treatment of the symptoms of PD as well as for neuroprotective effects, and several NMDA and AMPA receptor antagonists have progressed to clinical trials. More recently, there has been substantial progress in the development of metabotropic glutamate receptor (mGluR) modulators. The recent clinical proof‐of‐concept for the treatment of LIDs with mGluR5 negative modulators has demonstrated the potential clinical significance of this approach, and positive modulators or agonists at mGluR4 also look very promising. In this chapter we will review the development and current status of compounds that modulate iGluRs and mGluRs for the treatment of PD and illustrate the challenges and opportunities that these compounds present.

A series of potent non-acetylinic negative allosteric modulators of the metabotropic glutamate receptor 5 (mGlu5 NAMs) was developed starting from HTS screening hit 1. Potency was improved via iterative SAR, and physicochemical properties were optimized to deliver orally bioavailable compounds acceptable for in vivo testing. A lead molecule from the series demonstrated dose-dependent activity in the second phase of the rat formalin test from 30 mg/kg, and a preliminary PK/PD relationship was established.

Metabotropic glutamate receptor 7 (mGlu(7)) has been suggested to be a promising novel target for treatment of a range of disorders, including anxiety, post-traumatic stress disorder, depression, drug abuse, and schizophrenia. Here we characterized a potent and selective mGlu(7) negative allosteric modulator (NAM) (+)-6-(2,4-dimethylphenyl)-2-ethyl-6,7-dihydrobenzo[d]oxazol-4(5H)-one (ADX71743). In vitro, Schild plot analysis and reversibility tests at the target confirmed the NAM properties of the compound and attenuation of L-(+)-2-amino-4-phosphonobutyric acid-induced synaptic depression confirmed activity at the native receptor. The pharmacokinetic analysis of ADX71743 in mice and rats revealed that it is bioavailable after s.c. administration and is brain penetrant (cerebrospinal fluid concentration/total plasma concentration ratio at C(max) = 5.3%). In vivo, ADX71743 (50, 100, 150 mg/kg, s.c.) caused no impairment of locomotor activity in rats and mice or activity on rotarod in mice. ADX71743 had an anxiolytic-like profile in the marble burying and elevated plus maze tests, dose-dependently reducing the number of buried marbles and increasing open arm exploration, respectively. Whereas ADX71743 caused a small reduction in amphetamine-induced hyperactivity in mice, it was inactive in the mouse 2,5-dimethoxy-4-iodoamphetamine-induced head twitch and the rat conditioned avoidance response tests. In addition, the compound was inactive in the mouse forced swim test. These data suggest that ADX71743 is a suitable compound to help unravel the physiologic role of mGlu(7) and to better understand its implication in central nervous system diseases. Our in vivo tests using ADX71743, reported here, suggest that pharmacological inhibition of mGlu(7) is a valid approach for developing novel pharmacotherapies to treat anxiety disorders, but may not be suitable for treatment of depression or psychosis.

Positive allosteric modulators (PAMs) of metabotropic glutamate receptor 4 (mGluR4) have been proposed as a novel therapeutic approach for the treatment of Parkinson's disease. However, evaluation of this proposal has been limited by the availability of appropriate pharmacological tools to interrogate the target. In this study, we describe the properties of a novel mGluR4 PAM. 5-Methyl-N-(4-methylpyrimidin-2-yl)-4-(1H-pyrazol-4-yl)thiazol-2-amine (ADX88178) enhances glutamate-mediated activation of human and rat mGluR4 with EC(50) values of 4 and 9 nM, respectively. The compound is highly selective for mGluR4 with minimal activities at other mGluRs. Oral administration of ADX88178 in rats is associated with high bioavailability and results in cerebrospinal fluid exposure of >50-fold the in vitro EC(50) value. ADX88178 reverses haloperidol-induced catalepsy in rats at 3 and 10 mg/kg. It is noteworthy that this compound alone has no impact on forelimb akinesia resulting from a bilateral 6-hydroxydopamine lesion in rats. However, coadministration of a low dose of L-DOPA (6 mg/kg) enabled a robust, dose-dependent reversal of the forelimb akinesia deficit. ADX88178 also increased the effects of quinpirole in lesioned rats and enhanced the effects of L-DOPA in MitoPark mice. It is noteworthy that the enhancement of the actions of L-DOPA was not associated with an exacerbation of L-DOPA-induced dyskinesias in rats. ADX88178 is a novel, potent, and selective mGluR4 PAM that is a valuable tool for exploring the therapeutic potential of mGluR4 modulation. The use of this novel tool molecule supports the proposal that activation of mGluR4 may be therapeutically useful in Parkinson's disease.

INTRODUCTION AND OBJECTIVES: GABA is important for micturition control. The GABA-BR agonist baclofen reduces urethral resistance and detrusor overactivity in patients with spasticity. However, baclofen’s side effects limit its use in overactive bladder (OAB). Anti-muscarinics are standard treatment for OAB, but these have use-limiting anticholinergic effects. ADX71441 is a novel, orally active GABA-BR positive allosteric modulator with potentially improved safety and pharmacokinetics over baclofen and no anticholinergic side effect profile. ADX71441 was studied in a diuretic stress-induced preclinical model of OAB and its efficacy compared to the muscarinic oxybutynin. METHODS: Male C57BL/6 mice, food-restricted pre-experiment, were left untreated or given vehicle, ADX71441 1, 3, 10 mg/kg or oxybutynin 100 mg/kg p.o. (n 8/group). Treated mice received water 1ml s.c. 55 min later, followed by furosemide. First micturition event latency, micturition frequency, total and average micturition volumes were assessed for 90 min post diuretic. RESULTS: Administration of ADX71441 dose-dependently prolonged micturition latency, reduced micturition frequency, and volumes. Efficacy was statistically significant for ADX71441 (10 mg/kg) which returned most parameters to untreated control levels and was similar to oxybutynin. CONCLUSIONS: In the diuretic stress-induced OAB model, ADX71441 showed clinically relevant improvements on urinary parameters, comparable to oxybutinin at the 10 mg/kg dose. GABA-BR positive modulation by ADX71441 has potential as a novel approach to OAB treatment.

Metabotropic glutamate receptors (mGluRs) belong to the Class C G-protein coupled receptor and are activated by glutamate, a major neurotransmitter in the brain. The widespread expression of mGluR, in particular, mGluR2 and mGluR5 subtypes, throughout the central nervous system has made those two receptors attractive therapeutic targets for the treatment of severe neurological disorders, such as schizophrenia, anxiety, Parkinson's disease levodopa-induced dyskinesia, fragile X syndrome, and major depressive disorders. This review therefore focuses on the drug discovery efforts and clinical status of mGluR2 activators acting as orthosteric agonists or positive allosteric modulators as well as negative allosteric modulators of mGluR5.

International audience; There is growing evidence suggesting that antagonists of group II metabotropic glutamate receptors (mGluR2/3) exhibit antidepressant-like properties in several preclinical models of depression. However, all those studies have been performed using competitive group II non-selective orthosteric antagonists. In this study we extensively characterized a group II selective negative allosteric modulator (4-[3-(2,6-Dimethylpyridin-4-yl)phenyl]-7-methyl-8-trifluoromethyl-1,3-dihydrobenzo[b][1,4]diazepin-2-one, namely RO4491533, Woltering et al., 2010) in several in vitro biochemical assays and in vivo models of depression. In vitro, RO4491533 completely blocked the glutamate-induced Ca(2+) mobilization and the glutamate-induced accumulation in [(35)S]GTP(γS) binding in cells expressing recombinant human or rat mGluR2 and in native tissues. Results from Schild plot experiments and reversibility test at the target on both cellular and membrane-based assays confirmed the negative allosteric modulator properties of the compound. RO4491533 was equipotent on mGluR2 and mGluR3 receptors but not active on any other mGluRs. RO4491533 has acceptable PK properties in mice and rats, is bioavailable following oral gavage (F = 30%) and brain-penetrant (CSF conc/total plasma conc ratio = 0.8%). RO4491533 appeared to engage the central mGluR2 and mGluR3 receptors since the compound reversed the hypolocomotor effect of an mGluR2/3 orthosteric agonist LY379268 in a target-specific manner, as did the group II orthosteric mGluR2/3 antagonist LY341495. RO4491533 and LY341495 dose-dependently reduced immobility time of C57Bl6/J mice in the forced swim test. Also, RO4491533 and LY341495 were active in the tail suspension test in a line of Helpless (H) mice, a putative genetic model of depression. These data suggest that mGluR2/3 receptors are viable targets for development of novel pharmacotherapies for depression.

A series of N-propyl-8-chloro-6-substituted isoquinolones was identified as positive allosteric modulators of metabotropic glutamate receptor 2 (mGluR2 PAM) via high throughput screening (HTS). The subsequent synthesis and initial SAR exploration that led to the identification of compound 28 is described.

High quality gamete production in males and females requires the pituitary gonadotropin follicle stimulating hormone (FSH). In this report a novel chemical class of small molecule inhibitors of FSH receptor (FSHR) is described. ADX61623, a negative allosteric modulator (NAM), increased the affinity of interaction between (125)I-hFSH and human FSHR (hFSHR) five fold. This form of FSHR occupied simultaneously by FSH and ADX61623 was inactive for cAMP and progesterone production in primary cultures of rat granulosa cells. In contrast, ADX61623 did not block estrogen production. This demonstrates for the first time, biased antagonism at the FSHR. To determine if ADX61623 blocked FSH induction of follicle development in vivo, a bioassay to measure follicular development and oocyte production in immature female rats was validated. ADX61623 was not completely effective in blocking FSH induced follicular development in vivo at doses up to 100mg/kg as oocyte production and ovarian weight gain were only moderately reduced. These data illustrate that FSHR couples to multiple signaling pathways in vivo. Suppression of one pool of FSHR uncouples Gαs and cAMP production, and decreases progesterone production. Occupancy of another pool of FSHR sensitizes granulosa cells to FSH induced estradiol production. Therefore, ADX61623 is a useful tool to investigate further the mechanism of the FSHR signaling dichotomy. This may lead to a greater understanding of the signaling infrastructure which enables estrogen biosynthesis and may prove useful in treating estrogen dependent disease.

The discovery of a novel, achiral pyridine class of potent and orally active neurokinin-1 (NK 1 ) receptor antagonists is described. The evaluation of this class is briefly outlined, leading to the identification of netupitant 21 and befetupitant 29 , two new proprietary chemical entities with high affinity and excellent CNS penetration.

A recently identified DPP-IV inhibitor (1) was found to induce phospholipidosis and to inhibit CYP3A4. A small series of less lipophilic and less amphiphilic analogues was synthesized in an effort to overcome these issues. One compound from this series was equipotent to 1, did not induce phospholipidosis and showed a reduced CYP3A4 inhibition.

The ATP-dependent drug efflux pump P-glycoprotein (P-gp) affects the absorption and disposition of many compounds. P-gp may also play role in clinically significant drug-drug interactions. Therefore, it is important to find potential substrates or inhibitors of P-gp early in the drug discovery process. To identify compounds that interact with this transporter, several P-gp assays were validated and compared by testing a set of 28 reference compounds, including inhibitors of cytochrome P450 3A4 (CYP3A4). The assays included in silico predictions, inhibition assays (based on cellular uptake of rhodamine-123 or calcein AM), and functional assays (ATPase activity assay and transcellular transport assay, the latter for a subset of compounds). In addition, species differences were studied in an indirect fluorescence indicator screening assay and test systems expressing porcine, mouse, or human P-gp. Our results suggest that several P-gp assays should be used in combination to classify compounds as substrates or inhibitors of P-gp. Recommendations are given on screening strategies which can be applied to different phases of the drug discovery and development process.

A small series of aryl pyridyl sulfones has been prepared and investigated for its 5-HT(6) receptor binding properties. Thereof, pyrrolidinyl derivative 11 proved to be a very potent (pK(i) 9) and selective 5-HT(6) receptor antagonist. By means of in vivo microdialysis in the frontal cortex and a passive avoidance paradigm, where 11 reversed a scopolamine induced retention deficit, a functional correlation between 5-HT(6) receptors and cholinergic neurotransmission could be shown, supporting the therapeutic potential of 5-HT(6) receptors in the treatment of cognitive deficits.

Novel hexahydrospiro[piperidine-4,1'-pyrrolo[3,4-c]pyrroles that act as potent and selective orphanin FQ/nociceptin (N/OFQ) receptor (NOP) agonists were identified. The best compound, (+)-5a, potently inhibited 3H-N/OFQ binding to the NOP receptor (K(i) = 0.49 nM) but was1000-fold less potent in binding to MOP, KOP, and DOP opiate receptors. Further, (+)-5a potently stimulated GTP gamma S binding to NOP membranes (EC50 = 65 nM) and inhibited forskolin-mediated cAMP accumulation in NOP-expressing cells (EC50 = 9.1 nM) with a potency comparable to that of the natural peptide agonist N/OFQ. These results indicate that (+)-5a is a highly selective and potent small-molecule full agonist of the NOP receptor.

Tienilic Acid (TA) is a uricosuric drug marketed in 1978 and which caused a number of rare immunoallergic hepatitis. It was withdrawn in US in 1980, in France in 1992. Early batches of tienilic acid also contained 0.1–0.5% tienilic acid isomer. Tienilic acid isomer (TAI), has been shown to be metabolised by Cytochrome P450 into a reactive thiophene 1-oxide which either binds to proteins, or can be trapped by sulfur nucleophiles (Valadon et al. 1996). Tienilic acid is metabolized by human cytochrome P450 2C9 into 5-hydroxytienilic acid (a major metabolite representing 70% of the dose excreted in human urine) but it also forms (a) reactive metabolite(s) which binds covalently to CYP 2C9 and it is a mechanism based inhibitor of CYP 2C9. Adding glutathione to incubations decreases the covalent binding, but only to 1 mol/mol P450. However the reactive metabolite of tienilic acid is still unknown. Recently Koenigs et al. have shown using ESI-LC-MS that CYP 2C9 binds ≈ 2 mol of TA in absence of GSH and only one in presence of 3 mM GSH (Koenigs et al. 1999).

The biochemical and behavioral effects of a nonpeptidic, selective, and brain-penetrant agonist at the ORL1 receptor are reported herein. This low molecular weight compound {(1 S ,3a S )-8- (2,3,3a,4,5,6-hexahydro-1 H -phenalen-1-yl)-1-phenyl-1,3,8-triaza- spiro[4.5]decan-4-one} has high affinity for recombinant human ORL1 receptors and has 100-fold selectivity for ORL1 over other members of the opioid receptor family. It is a full agonist at these receptors and elicits dose-dependent anxiolytic-like effects in a set of validated models of distinct types of anxiety states in the rat (i.e., elevated plus-maze, fear-potentiated startle, and operant conflict). When given systemically, the compound has an efficacy and potency comparable to those of a benzodiazepine anxiolytic such as alprazolam or diazepam. However, this compound is differentiated from a classical benzodiazepine anxiolytic by a lack of efficient anti-panic-like activity, absence of anticonvulsant properties, and lack of effects on motor performance and cognitive function at anxiolytic doses (0.3 to 3 mg/kg i.p.). No significant change in intracranial self-stimulation performance and pain reactivity was observed in this dose range. Higher doses of this compound (≥10 mg/kg) induced disruption in rat behavior. These data confirm the notable anxiolytic-like effects observed at low doses with the orphanin FQ/nociceptin neuropeptide given locally into the brain and support a role for orphanin FQ/nociceptin in adaptive behavioral fear responses to stress.