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

Withaferin A maintained microbiome and metabolome features in A53T transgenic mice via multi-omics integrated analysis

BACKGROUND

Withaferin A (WFA), a naturally occurring compound, has shown promise as a therapeutic agent for Parkinson's disease (PD), a neurodegenerative disorder associated with motor and gastrointestinal dysfunctions. However, its effects on gut microbiota metabolism remain poorly understood.

PURPOSE

This study aimed to elucidate the neuroprotective mechanisms of WFA in a PD mouse model by investigating its regulation of gut microbiota composition, metabolic pathways, and correlations with brain spatial metabolomics.

METHODS

Human SNCA-transgenic (A53T) mice were treated with WFA and evaluated using behavioral tests, immunohistochemistry, Western blot, and ELISA to assess motor/cognitive functions and PD-related pathology. Gut microbiota composition was analyzed via 16S rRNA sequencing, while untargeted fecal metabolomics and brain spatial metabolomics were employed to identify metabolic alterations.

RESULTS

WFA significantly improved motor performance, alleviated cognitive deficits, restored intestinal barrier integrity, and reduced neuroinflammation. It elevated the abundance of anti-inflammatory gut bacteria (e.g., Bifidobacterium, Dubosiella, Akkermansia) and reversed 55 fecal metabolites linked to sphingolipid metabolism, serotonergic synapses, and neuroactive ligand- receptor interactions. Spatial metabolomics revealed WFA's regulation of sphingolipid signaling pathways, including sphingosine kinase (Sphk1), ceramidase, sphingosine 1-phosphate receptor (S1PR5), and endocannabinoid receptor CB2 expression. Correlation analysis indicated a link between brain metabolite content and gut microbiota abundance.

CONCLUSION

Our findings highlight a potential mechanism of WFA that repairs neurons by modulating the sphingolipid signaling pathway within the microbiota-gut-brain axis.

Experimental Therapeutics in Parkinson's Disease: A Review

The prevalence and burden of Parkinson's disease (PD) is rising. Motor symptoms are primarily treated with dopamine replacement, although with limitations and complications over time. Advances in PD research include new drug candidates and innovative repurposing of existing drugs targeting various molecular mechanisms. Several agents are under Food and Drug Administration review, highlighting the dynamic progress in the field. This review summarizes the latest experimental therapies for PD, including both motor and nonmotor symptom treatments. A total of 147 studies were included, examining new dopaminergic and nondopaminergic therapies, innovative drug formulations, and approaches to managing motor complications and nonmotor symptoms.

CVN424, a GPR6 inverse agonist, for Parkinson's disease and motor fluctuations: a double-blind, randomized, phase 2 trial

Background

CVN424 is a GPR6 inverse agonist that provides selective pharmacological control of the indirect striatopallidal pathway. We assessed the safety and efficacy of CVN424 as an adjunctive treatment to levodopa for reducing OFF-time in individuals with Parkinson's disease (PD) experiencing motor-fluctuations.

Methods

This was a randomised, double-blind, placebo-controlled study conducted at 21 sites across the United States to evaluate two doses of CVN424 (NCT04191577). Patients with PD (Hoehn and Yahr stages 2-4) who were on a stable dose of levodopa and experiencing ≥2 h of daily OFF-time were randomised (1:1:1) to receive either once-daily CVN424 (50 mg or 150 mg) or placebo for a 28-day treatment period. The primary endpoints were safety and tolerability. The key secondary endpoint was the change from baseline to Day 27 in OFF-time.

Findings

The study was conducted from December 23, 2019, to October 14, 2021. Out of 198 participants screened, 141 eligible participants were randomised to one of the three treatment groups (n = 47 per group), and 127 participants completed the 28-day treatment period. The most common treatment emergent adverse events (TEAEs) were headache (2% with CVN424 50 mg, 9% with CVN424 150 mg, and 2% with placebo) and nausea (4% with CVN424 50 mg, 6% with CVN424 150 mg and 2% with placebo). No serious treatment-related adverse events were reported. On Day 27, the mean ± standard deviation (SD) change from baseline in daily OFF-time was -1.3 ± 3.0 h in the CVN424 50 mg group, -1.6 ± 2.5 h in the CVN424 150 mg group, and -0.5 ± 2.9 h in the placebo group. The placebo-adjusted LS mean ± standard error (SE) treatment difference was significant for the CVN424 150 mg dose (1.3 ± 0.56 h, [95 CI% -2.41 to -0.19], nominal p = 0.02).

Interpretation

Treatment with CVN424 was safe and well-tolerated. Despite the short study duration and small sample size, the 150 mg CVN424 dose provided a clinically meaningful reduction in daily OFF-time. This study supports the development of CVN424 for the treatment of PD.

Funding

Cerevance.

Molecular insights into orphan G protein-coupled receptors relevant to schizophrenia

Schizophrenia remains a sizable socio-economic burden that continues to be treated with therapeutics based on 70-year old science. All currently approved therapeutics primarily target the dopamine D2 receptor to achieve their efficacy. Whilst dopaminergic dysregulation is a key feature in this disorder, the targeting of dopaminergic machinery has yielded limited efficacy and an appreciable side effect burden. Over the recent decades, numerous drugs that engage non-dopaminergic G protein-coupled receptors (GPCRs) have yielded a promise of efficacy without the deleterious side effect profile, yet none have successfully completed clinical studies and progressed to the market. More recently, there has been increased attention around non-dopaminergic GPCR-targeting drugs, which demonstrated efficacy in some schizophrenia symptom domains. This provides renewed hope that effective schizophrenia treatment may lie outside of the dopaminergic space. Despite the potential for muscarinic receptor- (and other well-characterised GPCR families) targeting drugs to treat schizophrenia, they are often plagued with complications such as lack of receptor subtype selectivity and peripheral on-target side effects. Orphan GPCR studies have opened a new avenue of exploration with many demonstrating schizophrenia-relevant mechanisms and a favourable expression profile, thus offering potential for novel drug development. This review discusses centrally expressed orphan GPCRs: GPR3, GPR6, GPR12, GPR52, GPR85, GPR88 and GPR139 and their relationship to schizophrenia. We review their expression, signalling mechanisms and cellular function, in conjunction with small molecule development and structural insights. We seek to provide a snapshot of the growing evidence and development potential of new classes of schizophrenia therapeutics. LINKED ARTICLES: This article is part of a themed issue Therapeutic Targeting of G Protein-Coupled Receptors: hot topics from the Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists 2021 Virtual Annual Scientific Meeting. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.14/issuetoc.

Discovery of 3-((4-Benzylpyridin-2-yl)amino)benzamides as Potent GPR52 G Protein-Biased Agonists

Orphan GPR52 is emerging as a promising neurotherapeutic target. Optimization of previously reported lead 4a employing an iterative drug design strategy led to the identification of a series of unique GPR52 agonists, such as 10a (PW0677), 15b (PW0729), and 24f (PW0866), with improved potency and efficacy. Intriguingly, compounds 10a and 24f showed greater bias for G protein/cAMP signaling and induced significantly less in vitro desensitization than parent compound 4a, indicating that reducing GPR52 β-arrestin activity with biased agonism results in sustained GPR52 activation. Further exploration of compounds 15b and 24f indicated improved potency and efficacy, and excellent target selectivity, but limited brain exposure warranting further optimization. These balanced and biased GPR52 agonists provide important pharmacological tools to study GPR52 activation, signaling bias, and therapeutic potential for neuropsychiatric and neurological diseases.

ERNEST COST action overview on the (patho)physiology of GPCRs and orphan GPCRs in the nervous system

G protein-coupled receptors (GPCRs) are a large family of cell surface receptors that play a critical role in nervous system function by transmitting signals between cells and their environment. They are involved in many, if not all, nervous system processes, and their dysfunction has been linked to various neurological disorders representing important drug targets. This overview emphasises the GPCRs of the nervous system, which are the research focus of the members of ERNEST COST action (CA18133) working group 'Biological roles of signal transduction'. First, the (patho)physiological role of the nervous system GPCRs in the modulation of synapse function is discussed. We then debate the (patho)physiology and pharmacology of opioid, acetylcholine, chemokine, melatonin and adhesion GPCRs in the nervous system. Finally, we address the orphan GPCRs, their implication in the nervous system function and disease, and the challenges that need to be addressed to deorphanize them.

Orphan peptide and G protein-coupled receptor signalling in alcohol use disorder

Neuropeptides and G protein-coupled receptors (GPCRs) have long been, and continue to be, one of the most popular target classes for drug discovery in CNS disorders, including alcohol use disorder (AUD). Yet, orphaned neuropeptide systems and receptors (oGPCR), which have no known cognate receptor or ligand, remain understudied in drug discovery and development. Orphan neuropeptides and oGPCRs are abundantly expressed within the brain and represent an unprecedented opportunity to address brain function and may hold potential as novel treatments for disease. Here, we describe the current literature regarding orphaned neuropeptides and oGPCRs implicated in AUD. Specifically, in this review, we focus on the orphaned neuropeptide cocaine- and amphetamine-regulated transcript (CART), and several oGPCRs that have been directly implicated in AUD (GPR6, GPR26, GPR88, GPR139, GPR158) and discuss their potential and pitfalls as novel treatments, and progress in identifying their cognate receptors or ligands.

Targeting G Protein-Coupled Receptors in the Treatment of Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disease characterized in part by the deterioration of dopaminergic neurons which leads to motor impairment. Although there is no cure for PD, the motor symptoms can be treated using dopamine replacement therapies including the dopamine precursor L-DOPA, which has been in use since the 1960s. However, neurodegeneration in PD is not limited to dopaminergic neurons, and many patients experience non-motor symptoms including cognitive impairment or neuropsychiatric disturbances, for which there are limited treatment options. Moreover, there are currently no treatments able to alter the progression of neurodegeneration. There are many therapeutic strategies being investigated for PD, including alternatives to L-DOPA for the treatment of motor impairment, symptomatic treatments for non-motor symptoms, and neuroprotective or disease-modifying agents. G protein-coupled receptors (GPCRs), which include the dopamine receptors, are highly druggable cell surface proteins which can regulate numerous intracellular signaling pathways and thereby modulate the function of neuronal circuits affected by PD. This review will describe the treatment strategies being investigated for PD that target GPCRs and their downstream signaling mechanisms. First, we discuss new developments in dopaminergic agents for alleviating PD motor impairment, the role of dopamine receptors in L-DOPA induced dyskinesia, as well as agents targeting non-dopamine GPCRs which could augment or replace traditional dopaminergic treatments. We then discuss GPCRs as prospective treatments for neuropsychiatric and cognitive symptoms in PD. Finally, we discuss the evidence pertaining to ghrelin receptors, β-adrenergic receptors, angiotensin receptors and glucagon-like peptide 1 receptors, which have been proposed as disease modifying targets with potential neuroprotective effects in PD.