A Phase I, First-in-Human, Healthy Volunteer Study to Investigate the Safety, Tolerability, and Pharmacokinetics of CVN424, a Novel G Protein-Coupled Receptor 6 Inverse Agonist for Parkinson's Disease.

CVN424 is a novel small molecule and first-in-class candidate therapeutic to selectively modulate GPR6, an orphan G-protein coupled receptor. Expression of GPR6 is largely confined to the subset of striatal projection neurons that give rise to the indirect (striatopallidal) pathway, important in the control of movement. CVN424 improves motor function in preclinical animal models of Parkinson's disease. Here, we report results of a phase 1, first-in-human study investigating the safety, tolerability, and pharmacokinetics of CVN424 in healthy volunteers. The study (NCT03657030) was randomized, double-blind, and placebo controlled. CVN424 was orally administered in ascending doses to successive cohorts as inpatients in a clinical research unit. Single doses ranged from 1 mg to 225 mg, and repeated (7 day) daily doses were 25, 75, or 150 mg. CVN424 peak plasma concentrations were reached within 2 h post-dose in the fasted state and increased with increasing dose. Dosing after a standardized high-fat meal reduced and delayed the peak plasma concentration, but total plasma exposure was similar. Mean terminal half-life ranged from 30 to 41 h. CVN424 was generally well tolerated: no serious or severe adverse effects were observed, and there were no clinically significant changes in vital signs or laboratory parameters. We conclude that CVN424, a nondopaminergic compound that modulates a novel therapeutic target, was safe and well tolerated. A phase 2 study in patients with Parkinson's disease is underway. SIGNIFICANCE STATEMENT: This is the first-in-human clinical study of a first-in-class candidate therapeutic. CVN424 modulates a novel drug target, GPR6, which is selectively expressed in a pathway in the brain that has been implicated in the motor dysfunction of patients with Parkinson's disease. This study paves the way for investigating this novel mechanism of action in patients with Parkinson's disease.

Structure-Based Exploration of Selectivity for ATM Inhibitors in Huntington's Disease.

Our group has recently shown that brain-penetrant ataxia telangiectasia-mutated (ATM) kinase inhibitors may have potential as novel therapeutics for the treatment of Huntington's disease (HD). However, the previously described pyranone-thioxanthenes (e.g., 4) failed to afford selectivity over a vacuolar protein sorting 34 (Vps34) kinase, an important kinase involved with autophagy. Given that impaired autophagy has been proposed as a pathogenic mechanism of neurodegenerative diseases such as HD, achieving selectivity over Vps34 became an important objective for our program. Here, we report the successful selectivity optimization of ATM over Vps34 by using X-ray crystal structures of a Vps34-ATM protein chimera where the Vps34 ATP-binding site was mutated to approximate that of an ATM kinase. The morpholino-pyridone and morpholino-pyrimidinone series that resulted as a consequence of this selectivity optimization process have high ATM potency and good oral bioavailability and have lower molecular weight, reduced lipophilicity, higher aqueous solubility, and greater synthetic tractability compared to the pyranone-thioxanthenes.

Evaluation of 5-(Trifluoromethyl)-1,2,4-oxadiazole-Based Class IIa HDAC Inhibitors for Huntington's Disease.

Using an iterative structure-activity relationship driven approach, we identified a CNS-penetrant 5-(trifluoromethyl)-1,2,4-oxadiazole (TFMO, 12) with a pharmacokinetic profile suitable for probing class IIa histone deacetylase (HDAC) inhibition in vivo. Given the lack of understanding of endogenous class IIa HDAC substrates, we developed a surrogate readout to measure compound effects in vivo, by exploiting the >100-fold selectivity compound 12 exhibits over class I/IIb HDACs. We achieved adequate brain exposure with compound 12 in mice to estimate a class I/IIb deacetylation EC50, using class I substrate H4K12 acetylation and global acetylation levels as a pharmacodynamic readout. We observed excellent correlation between the compound 12 in vivo pharmacodynamic response and in vitro class I/IIb cellular activity. Applying the same relationship to class IIa HDAC inhibition, we estimated the compound 12 dose required to inhibit class IIa HDAC activity, for use in preclinical models of Huntington's disease.

Optimization of Potent and Selective Ataxia Telangiectasia-Mutated Inhibitors Suitable for a Proof-of-Concept Study in Huntington's Disease Models.

Genetic and pharmacological evidence indicates that the reduction of ataxia telangiectasia-mutated (ATM) kinase activity can ameliorate mutant huntingtin (mHTT) toxicity in cellular and animal models of Huntington's disease (HD), suggesting that selective inhibition of ATM could provide a novel clinical intervention to treat HD. Here, we describe the development and characterization of ATM inhibitor molecules to enable in vivo proof-of-concept studies in HD animal models. Starting from previously reported ATM inhibitors, we aimed with few modifications to increase brain exposure by decreasing P-glycoprotein liability while maintaining potency and selectivity. Here, we report brain-penetrant ATM inhibitors that have robust pharmacodynamic (PD) effects consistent with ATM kinase inhibition in the mouse brain and an understandable pharmacokinetic/PD (PK/PD) relationship. Compound 17 engages ATM kinase and shows robust dose-dependent inhibition of X-ray irradiation-induced KAP1 phosphorylation in the mouse brain. Furthermore, compound 17 protects against mHTT (Q73)-induced cytotoxicity in a cortical-striatal cell model of HD.

Development and characterization of a CNS-penetrant benzhydryl hydroxamic acid class IIa histone deacetylase inhibitor.

We have identified a potent, cell permeable and CNS penetrant class IIa histone deacetylase (HDAC) inhibitor 22, with >500-fold selectivity over class I HDACs (1,2,3) and ∼150-fold selectivity over HDAC8 and the class IIb HDAC6 isoform. Dose escalation pharmacokinetic analysis demonstrated that upon oral administration, compound 22 can reach exposure levels in mouse plasma, muscle and brain in excess of cellular class IIa HDAC IC50 levels for ∼8 h. Given the interest in aberrant class IIa HDAC function for a number of neurodegenerative, neuromuscular, cardiac and oncology indications, compound 22 (also known as CHDI-390576) provides a selective and potent compound to query the role of class IIa HDAC biology, and the impact of class IIa catalytic site occupancy in vitro and in vivo.

Potent, Selective, and CNS-Penetrant Tetrasubstituted Cyclopropane Class IIa Histone Deacetylase (HDAC) Inhibitors.

Potent and selective class IIa HDAC tetrasubstituted cyclopropane hydroxamic acid inhibitors were identified with high oral bioavailability that exhibited good brain and muscle exposure. Compound 14 displayed suitable properties for assessment of the impact of class IIa HDAC catalytic site inhibition in preclinical disease models.

Design, synthesis, and biological evaluation of potent and selective class IIa histone deacetylase (HDAC) inhibitors as a potential therapy for Huntington's disease.

Inhibition of class IIa histone deacetylase (HDAC) enzymes have been suggested as a therapeutic strategy for a number of diseases, including Huntington's disease. Catalytic-site small molecule inhibitors of the class IIa HDAC4, -5, -7, and -9 were developed. These trisubstituted diarylcyclopropanehydroxamic acids were designed to exploit a lower pocket that is characteristic for the class IIa HDACs, not present in other HDAC classes. Selected inhibitors were cocrystallized with the catalytic domain of human HDAC4. We describe the first HDAC4 catalytic domain crystal structure in a "closed-loop" form, which in our view represents the biologically relevant conformation. We have demonstrated that these molecules can differentiate class IIa HDACs from class I and class IIb subtypes. They exhibited pharmacokinetic properties that should enable the assessment of their therapeutic benefit in both peripheral and CNS disorders. These selective inhibitors provide a means for evaluating potential efficacy in preclinical models in vivo.

Pyrazolopyridazine alpha-2-delta-1 ligands for the treatment of neuropathic pain.

Optimization of the novel alpha-2-delta-1 ligand 4 provided compounds 37 and 38 which have improved DMPK profiles, good in vivo analgesic activity and in vitro selectivity over alpha-2-delta-2. An in-house P-gp prediction programme and the MetaSite software package were used to help solve the specific problems of high P-gp efflux and high in vivo clearance.

The discovery and optimisation of benzazepine sulfonamide and sulfones as potent agonists of the motilin receptor.

Optimisation of a series of benzazepine sulfonamide hit compounds identified from high throughput screening led to the discovery of a new series of tractable, potent motilin receptor agonists.

Discovery of N-(3-fluorophenyl)-1-[(4-([(3S)-3-methyl-1-piperazinyl]methyl)phenyl)acetyl]-4-piperidinamine (GSK962040), the first small molecule motilin receptor agonist clinical candidate.

N-(3-fluorophenyl)-1-[(4-([(3S)-3-methyl-1-piperazinyl]methyl)phenyl)acetyl]-4-piperidinamine 12 (GSK962040) is a novel small molecule motilin receptor agonist. It possesses excellent activity at the recombinant human motilin receptor and also at the native rabbit motilin receptor where its agonist activity results in potentiation of the amplitude of neuronal-mediated contractions of isolated gastric antrum tissue. Compound 12 also possesses highly promising pharmacokinetic profiles in both rat and dog, and these results, in combination with further profiling in human native tissue and an in vivo model of gastrointestinal transit in the rabbit, have led to its selection as a candidate for further development.

The discovery of biaryl carboxamides as novel small molecule agonists of the motilin receptor.

Optimisation of urea (5), identified from high throughput screening and subsequent array chemistry, has resulted in the identification of pyridine carboxamide (33) which is a potent motilin receptor agonist possessing favourable physicochemical and ADME profiles. Compound (33) has demonstrated prokinetic-like activity both in vitro and in vivo in the rabbit and therefore represents a promising novel small molecule motilin receptor agonist for further evaluation as a gastroprokinetic agent.

Noradrenergic changes, aggressive behavior, and cognition in patients with dementia.

BACKGROUND: We wished to examine the integrity of the noradrenergic system in patients with Alzheimer's disease, mixed/other dementias and controls, and possible relationships between changes in the noradrenergic system and the presence of behavioral and psychiatric signs and symptoms in dementia. METHODS: Alpha(2) adrenoceptor sites were measured by radioligand binding in three cortical regions of 46 individuals with dementia and 33 elderly normal controls together with cortical noradrenaline concentration and locus coeruleus cell and neurofibrillary tangle counts. RESULTS: The alpha(2) adrenergic receptor density was unaltered in patients with Alzheimer's disease, mixed/other dementias compared with controls; however, there was a loss of locus coeruleus cells in subjects with dementia, reaching 50% within the rostral nucleus. In addition, a significant reduction was seen in the midtemporal cortical noradrenaline concentration (31% decrease) in patients with Alzheimer's disease. In subjects with dementia, there was a positive correlation between aggressive behavior and magnitude of rostral locus coeruleus cell loss, while the reduction in noradrenaline concentration correlated with cognitive impairment. CONCLUSIONS: Subgroups of patients with Alzheimer's disease may have different neurochemical changes from patients lacking these changes. Therefore, this study may have implications for the treatment of behavioral and psychiatric signs and symptoms in dementia, particularly aggressive behavior in patients with dementia.