New potent calcimimetics: I. Discovery of a series of novel trisubstituted ureas.

Starting from Fendiline and R-568, we identified a novel series of urea compounds as positive allosteric modulators of the calcium sensing receptor (CaSR), as part of a program to identify novel therapeutics for secondary hyperparathyroidism. Initially identified disubstituted ureas were converted to trisubstituted urea lead 20e, which was further modified to increase in vivo potency. Replacing a carbomethoxy substituent by various bioisosteres led to compound 46 which exhibited potent in vitro and in vivo activity after oral administration.

New potent calcimimetics: II. Discovery of benzothiazole trisubstituted ureas.

Following the identification of trisubstituted ureas as a promising new chemical series of allosteric modulators of the calcium sensing receptor (CaSR), we further explored the SAR around the urea substitution, leading to the discovery of benzothiazole urea compound 13. This compound is a potent calcimimetic with an EC50=20 nM (luciferase assay). Evaluated in an in vivo model of chronic renal failure (short term and long term in 5/6 nephrectomized rats), benzothiazole urea 13 significantly decreased PTH levels after oral administration while keeping calcemia within the normal range.

Glutamatergic and dopaminergic modulation of cortico-striatal circuits probed by dynamic calcium imaging of networks reconstructed in microfluidic chips.

Although the prefrontal cortex and basal ganglia are functionally interconnected by parallel loops, cellular substrates underlying their interaction remain poorly understood. One novel approach for addressing this issue is microfluidics, a methodology which recapitulates several intrinsic and synaptic properties of cortico-subcortical networks. We developed a microfluidic device where cortical neurons projected onto striatal neurons in a separate compartment. We exploited real-time (low-resolution/high-output) calcium imaging to register network dynamics and characterize the response to glutamatergic and dopaminergic agents. Reconstructed cortico-striatal networks revealed the progressive appearance of cortical VGLUT1 clusters on striatal dendrites, correlating with the emergence of spontaneous and synchronous glutamatergic responses of striatal neurons to concurrent cortical stimulation. Striatal exposure to the NMDA receptor GluN2A subunit antagonist TCN201 did not affect network rhythm, whereas the GluN2B subunit antagonist RO256981 significantly decreased striatal activity. Dopamine application or the D2/D3 receptor agonist, quinpirole, decreased cortico-striatal synchrony whereas the D1 receptor agonist, SKF38393, was ineffective. These data show that cortico-striatal networks reconstructed in a microfluidic environment are synchronized and present characteristics close to those of their in situ counterparts. They should prove instructive for deciphering the molecular substrates of CNS disorders and evaluating the actions of novel therapeutic agents.

The confirmation rate of primary hits: a predictive model.

HTS data from primary screening are usually analyzed by setting a cutoff for activity, in order to minimize both false-negative and false-positive rates. An alternative approach, based on a calculated probability of being active, is presented here. Given the predicted confirmation rate derived from this probability, the number of primary positives selected for follow-up can be optimized to maximize the number of true positives without picking too many false positives. Typical cutoff-determining methods are more serendipitous in their nature and not easily optimized in an effort to optimize screening efforts. An additional advantage of calculating a probability of being active for each compound screened is that orthogonal mixtures can be deconvoluted without presetting a deconvolution threshold. An important consequence of using the probability of being active with orthogonal mixtures is that individual compound screening results can be recorded irrespective of whether the assays were performed on single compounds or on cocktails.

Discovery of diarylhydantoins as new selective androgen receptor modulators.

A novel selective androgen receptor modulator scaffold has been discovered through structural modifications of hydantoin antiandrogens. Several 4-(4-hydroxyphenyl)-N-arylhydantoins displayed partial agonism with nanomolar in vitro potency in transactivation experiments using androgen receptor (AR) transfected cells. In a standard castrated male rat model, several compounds showed good anabolic activity on levator ani muscle, dissociated from the androgenic activity on ventral prostate, after oral dosing at 30 mg/kg. (+)-4-[3,4-Dimethyl-2,5-dioxo-4-(4-hydroxyphenyl)imidazolidin-1-yl]-2-(trifluoromethyl)benzonitrile ((+)-11b) displayed anabolic potency with a strong dissociation between levator ani muscle and ventral prostate (A(50) = 0.5 mg/kg vs 70 mg/kg). The binding modes of two compounds, including (+)-11b, within the AR ligand-binding domain have been studied by cocrystallization experiments using a coactivator-like peptide. Both compounds bound to the same site, and the overall structures of the AR were very similar.

Identification of a 4-(hydroxymethyl)diarylhydantoin as a selective androgen receptor modulator.

Structural modification performed on a 4-methyl-4-(4-hydroxyphenyl)hydantoin series is described which resulted in the development of a new series of 4-(hydroxymethyl)diarylhydantoin analogues as potent, partial agonists of the human androgen receptor. This led to the identification of (S)-(-)-4-(4-(hydroxymethyl)-3-methyl-2,5-dioxo-4-phenylimidazolidin-1-yl)-2-(trifluoromethyl)benzonitrile ((S)-(-)-18a, GLPG0492) evaluated in vivo in a classical model of orchidectomized rat. In this model, (-)-18a exhibited anabolic activity on muscle, strongly dissociated from the androgenic activity on prostate after oral dosing. (-)-18a has very good pharmacokinetic properties, including bioavailability in rat (F > 50%), and is currently under evaluation in phase I clinical trials.

Nicotinic receptors: allosteric transitions and therapeutic targets in the nervous system.

Nicotinic receptors - a family of ligand-gated ion channels that mediate the effects of the neurotransmitter acetylcholine - are among the most well understood allosteric membrane proteins from a structural and functional perspective. There is also considerable interest in modulating nicotinic receptors to treat nervous-system disorders such as Alzheimer's disease, schizophrenia, depression, attention deficit hyperactivity disorder and tobacco addiction. This article describes both recent advances in our understanding of the assembly, activity and conformational transitions of nicotinic receptors, as well as developments in the therapeutic application of nicotinic receptor ligands, with the aim of aiding novel drug discovery by bridging the gap between these two rapidly developing fields.