Tapinarof validates the aryl hydrocarbon receptor as a therapeutic target: A clinical review.

The aryl hydrocarbon receptor (AhR) is a ligand-dependent transcription factor that has wide-ranging roles, including regulation of inflammation and homeostasis. AhR is not a cell surface receptor; rather, it exists in a cytoplasmic complex that responds to a wide variety of structurally dissimilar endogenous, microbial, and environmental ligands. The ubiquitous expression of AhR, its ability to be activated by a wide range of ligands, and its capacity to act as a master regulator for gene expression and homeostasis make it a promising new therapeutic target. Clinical trials of tapinarof cream have now validated AhR agonism as a therapeutic approach that can deliver significant efficacy for treating inflammatory skin diseases, including psoriasis and atopic dermatitis. Tapinarof 1% cream is a first-in-class, nonsteroidal, topical, AhR agonist with a pharmacokinetic profile that results in localized exposure at sites of disease, avoiding systemic safety concerns, drug interactions, or off-target effects. Psoriasis and atopic dermatitis both involve epidermal inflammation, cellular immune responses, dysregulation of skin barrier protein expression, and oxidative stress. On the basis of the clinical effectiveness of tapinarof cream for treating inflammatory skin diseases, we review how targeting AhR may offer a significant opportunity in other conditions that share key aspects of pathogenesis, including asthma, inflammatory bowel disease, eosinophilic esophagitis, ophthalmic, and nervous system diseases.

Pimavanserin for Parkinson's Disease psychosis: Effects stratified by baseline cognition and use of cognitive-enhancing medications.

BACKGROUND: PD psychosis is often associated with cognitive impairment, including dementia, and involves dopaminergic, serotonergic, and cholinergic mechanisms. OBJECTIVE: To evaluate the differential effect of the antipsychotic pimavanserin, a selective serotonin 2A receptor inverse agonist, in PD psychosis patients with versus without cognitive impairment and in those receiving versus not receiving cognitive-enhancing medications. METHODS: Data from the pivotal randomized clinical trial of pimavanserin for PD psychosis were stratified by (1) screening MMSE score as cognitively impaired (21-24) versus unimpaired (≥25) and (2) concomitant use versus nonuse of cognitive-enhancing medications. The primary outcome measure was change in the PD-adapted Scale for the Assessment of Positive Symptoms. RESULTS: Mean (pimavanserin vs. placebo) change from baseline was larger in the cognitively impaired (n = 50; -6.62 vs. -0.91; P = 0.002) versus the cognitively unimpaired (n = 135; -5.50 vs. -3.23; p = 0.046) group. The comparable change was -6.04 versus -2.18 (P = 0.012) and -5.66 versus -3.15 (P = 0.041) in patients treated (n = 69) and not treated (n = 116) with concomitant cognitive-enhancing medication. Pimavanserin was similarly tolerated across all cognitive groups with no additional safety concerns identified. Overall adverse event rates were comparable across the concomitant cognitive-enhancing medication groups; however, rates of serious adverse events and discontinuations attributed to adverse events were increased in patients taking cholinesterase inhibitors. CONCLUSIONS: The antipsychotic effect of pimavanserin is robust in PD patients with cognitive impairment and may be enhanced by concomitant cognitive-enhancing medication use. Future prospective studies are needed to confirm these preliminary findings. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Parkinson's disease and Parkinson's disease psychosis: a perspective on the challenges, treatments, and economic burden.

Parkinson's disease (PD) is a progressive neurodegenerative disease associated with a decrease in the neurotransmitter dopamine and characterized by the cardinal motor hallmarks of resting tremor, rigidity, bradykinesia/akinesia, and postural instability. Lesser-known features of PD revolve around nonmotor concerns including psychosis, dementia, sleep disturbances, autonomic dysfunction, and sensory abnormalities. Parkinson's disease psychosis (PDP) contributes significantly to morbidity, mortality, nursing home placement, and quality of life (QOL). PDP management suffers from a lack of safe, effective pharmacological agents and the opposing nature of atypical antipsychotics and dopaminergic therapies. Pimavanserin, the only atypical antipsychotic currently approved by the FDA for treating PDP-related hallucinations and delusions, has no appreciable affinity for dopaminergic receptors, and a controlled clinical study demonstrated its efficacy in treating PDP-associated hallucinations and delusions without affecting motor function. A recent analysis of all health resource utilization (HRU) and total costs attributable to PD and PDP found that mean 12-month HRU services per patient were 2.3 times higher and costs were 2.1 times higher in the PDP cases, while falls were 3.4 times higher and fractures 2.3 times higher, respectively. Products or services that prevent, delay, or lessen the severity of PDP may contribute to reduced healthcare system costs and improve the QOL of patients with PDP and of their caregivers.