Effect of TAAR1/5-HT(1A) agonist SEP-363856 on REM sleep in humans

Wakefulness Induced by TAAR1 Partial Agonism is Mediated Through Dopaminergic Neurotransmission

Trace amine-associated receptor 1 (TAAR1) is known to negatively regulate dopamine (DA) release. The partial TAAR1 agonist RO5263397 promotes wakefulness and suppresses NREM and REM sleep in mice, rats, and non-human primates. We tested the hypothesis that the TAAR1-mediated effects on sleep/wake were due, at least in part, to DA release. Male C57BL6/J mice (n=8) were intraperitoneally administered the D1R antagonist SCH23390, the D2R antagonist eticlopride, a combination of D1R+D2R antagonists or saline at ZT5.5, followed 30 min later by RO5263397 or vehicle (10% DMSO in DI water) at ZT6 per os . EEG, EMG, subcutaneous temperature, and activity were recorded in each mouse across the 8 treatment conditions and sleep architecture was analyzed for 6 hours post-dosing. Consistent with our previous reports, RO5263397 increased wakefulness as well as the latency to NREM and REM sleep. D1, D2, and D1+D2 pretreatment reduced RO5263397-induced wakefulness during the first 1-2 hours after dosing, but only the D1+D2 combination attenuated the wake-promoting effect of RO5263397 from ZT6-8, mostly by increasing NREM sleep. Although D1+D2 antagonism blocked the wake-promoting effect of RO5263397, only the D1 antagonist significantly reduced the TAAR1-mediated increase in NREM latency. Neither the D1 nor the D2 antagonist affected TAAR1-mediated suppression of REM sleep. These results suggest that, whereas TAAR1 effects on wakefulness are mediated in part through the D2R, D1R activation plays a role in reversing the TAAR1-mediated increase in NREM sleep latency. By contrast, TAAR1-mediated suppression of REM sleep appears not to involve D1R or D2R mechanisms.

Trace amine-associated receptor 1 (TAAR1) agonism for psychosis: a living systematic review and meta-analysis of human and non-human data

Background

Trace amine-associated receptor 1 (TAAR1) agonism shows promise for treating psychosis, prompting us to synthesise data from human and non-human studies.

Methods

We co-produced a living systematic review of controlled studies examining TAAR1 agonists in individuals (with or without psychosis/schizophrenia) and relevant animal models. Two independent reviewers identified studies in multiple electronic databases (until 17.11.2023), extracted data, and assessed risk of bias. Primary outcomes were standardised mean differences (SMD) for overall symptoms in human studies and hyperlocomotion in animal models. We also examined adverse events and neurotransmitter signalling. We synthesised data with random-effects meta-analyses.

Results

Nine randomised trials provided data for two TAAR1 agonists (ulotaront and ralmitaront), and 15 animal studies for 10 TAAR1 agonists. Ulotaront and ralmitaront demonstrated few differences compared to placebo in improving overall symptoms in adults with acute schizophrenia (N=4 studies, n=1291 participants; SMD=0.15, 95%CI: -0.05, 0.34), and ralmitaront was less efficacious than risperidone (N=1, n=156, SMD=-0.53, 95%CI: -0.86, -0.20). Large placebo response was observed in ulotaront phase-III trials. Limited evidence suggested a relatively benign side-effect profile for TAAR1 agonists, although nausea and sedation were common after a single dose of ulotaront. In animal studies, TAAR1 agonists improved hyperlocomotion compared to control (N=13 studies, k=41 experiments, SMD=1.01, 95%CI: 0.74, 1.27), but seemed less efficacious compared to dopamine D 2 receptor antagonists (N=4, k=7, SMD=-0.62, 95%CI: -1.32, 0.08). Limited human and animal data indicated that TAAR1 agonists may regulate presynaptic dopaminergic signalling.

Conclusions

TAAR1 agonists may be less efficacious than dopamine D 2 receptor antagonists already licensed for schizophrenia. The results are preliminary due to the limited number of drugs examined, lack of longer-term data, publication bias, and assay sensitivity concerns in trials associated with large placebo response. Considering their unique mechanism of action, relatively benign side-effect profile and ongoing drug development, further research is warranted.

Registration

PROSPERO-ID: CRD42023451628.

TAAR1 as an emerging target for the treatment of psychiatric disorders

Trace amines, a group of amines expressed at the nanomolar level in the mammalian brain, can modulate monoamine transmission. The discovery of and the functional research on the trace amine-associated receptors (TAARs), especially the most well-characterized TAAR1, have largely facilitated our understanding of the function of the trace amine system in the brain. TAAR1 is expressed in the mammalian brain at a low level and widely distributed in the monoaminergic system, including the ventral tegmental area and substantial nigra, where the dopamine neurons reside in the mammalian brain. Growing in vitro and in vivo evidence has demonstrated that TAAR1 could negatively modulate monoamine transmission and play a crucial role in many psychiatric disorders, including schizophrenia, substance use disorders, sleep disorders, depression, and anxiety. Notably, in the last two decades, many studies have repeatedly confirmed the pharmacological effects of the selective TAAR1 ligands in various preclinical models of psychiatric disorders. Recent clinical trials of the dual TAAR1 and serotonin receptor agonist ulotaront also revealed a potential efficacy for treating schizophrenia. Here, we review the current understanding of the TAAR1 system and the recent advances in the elucidation of behavioral and physiological properties of TAAR1 agonists evaluated both in preclinical animal models and clinical trials. We also discuss the potential TAAR1-dependent signaling pathways and the cellular mechanisms underlying the inhibitory effects of TAAR1 activation on drug addiction. We conclude that TAAR1 is an emerging target for the treatment of psychiatric disorders.

A Novel Method for Deriving Adverse Event Prevalence in Randomized Controlled Trials: Potential for Improved Understanding of Benefit-Risk Ratio and Application to Drug Labels

INTRODUCTION

Adverse event (AE) data in randomized controlled trials (RCTs) allow quantification of a drug's safety risk relative to placebo and comparison across medications. The standard US label for Food and Drug Administration-approved drugs typically lists AEs by MedDRA Preferred Term that occur at ≥ 2% in drug and with greater incidence than in placebo. We suggest that the drug label can be more informative for both patients and physicians if it includes, in addition to AE incidence (percent of subjects who reported the AE out of the total subjects in treatment), the absolute prevalence (percent of subject-days spent with an AE out of the total subject-days spent in treatment) and expected duration (days required for AE incidence to be reduced by half). We also propose a new method to analyze AEs in RCTs using drug-placebo difference in AE prevalence to improve safety signal detection.

METHODS

AE data from six RCTs in schizophrenia were analyzed (five RCTs of the dopamine D2 receptor-based antipsychotic lurasidone and one RCT of the novel trace amine-associated receptor 1 [TAAR1] agonist ulotaront). We determined incidence, absolute prevalence, and expected duration of AEs for lurasidone and ulotaront vs respective placebo. We also calculated areas under the curve of drug-placebo difference in AE prevalence and mean percent contribution of each AE to this difference.

RESULTS

A number of AEs with the same incidence had different absolute prevalence and expected duration. When accounting for these two parameters, AEs that did not appear in the 2% incidence tables of the drug label turned out to contribute substantially to drug tolerability. The percent contribution of a drug-related AE to the overall side effect burden increased the drug-placebo difference in AE prevalence, whereas the percent contribution of a placebo-related AE decreased such difference, revealing a continuum of risk between drug and placebo. AE prevalence curves for drug were generally greater than those for placebo. Ulotaront exhibited a small drug-placebo difference in AE prevalence curves due to a relatively low incidence and short duration of AEs in the ulotaront treatment arm as well as the emergence of disease-related AEs in the placebo arm.

CONCLUSION

Reporting AE absolute prevalence and expected duration for each RCT and incorporating them in the drug label is possible, is clinically relevant, and allows standardized comparison of medications. Our new metric, the drug-placebo difference in AE prevalence, facilitates signal detection in RCTs. We piloted this metric in RCTs of several neuropsychiatric indications and drugs, offering a new way to compare AE burden and tolerability among treatments using existing clinical trial information.

A Phase I, Open-Label, Fixed Sequence Study to Investigate the Effect of Cytochrome P450 2D6 Inhibition on the Pharmacokinetics of Ulotaront in Healthy Subjects

BACKGROUND

Ulotaront is a novel psychotropic agent with agonist activity at trace amine-associated receptor 1 (TAAR1) and 5-hydroxytryptamine type 1A (5-HT1A) receptors in phase III clinical development for the treatment of schizophrenia.

OBJECTIVE

This study aimed to investigate the effect of paroxetine, a strong cytochrome P450 (CYP) 2D6 inhibitor, on ulotaront pharmacokinetics (PK) in healthy volunteers.

METHODS

Subjects received a single oral dose of 25 mg ulotaront on Day 1 and an oral dose of 20 mg paroxetine once daily from Days 5 to 10 to achieve steady-state plasma paroxetine levels. On Day 11, subjects received another single oral dose of 25 mg ulotaront, with continued daily oral dosing of 20 mg paroxetine from Days 11 to 14. All 24 subjects were CYP2D6 normal metabolizers.

RESULTS

Coadministration of paroxetine increased ulotaront maximum observed plasma concentration (Cmax) and area under the plasma concentration-time curve from time zero to infinity (AUC∞) by 31% and 72%, respectively, and decreased ulotaront apparent clearance (CL/F) by approximately 42%. While coadministration of paroxetine increased AUC∞ of active but minor metabolite SEP-363854 by 32%, it had no effect on SEP-363854 Cmax, or on SEP-363854 to the ulotaront AUC from time zero to the last quantifiable concentration (AUClast) ratio. Based on the acceptable adverse event profile of ulotaront across previous phase II studies, the increase in ulotaront exposure is unlikely to be clinically meaningful.

CONCLUSIONS

Weak drug-drug interactions were observed between ulotaront and the strong CYP2D6 inhibitor paroxetine; however, dose adjustment as a precondition when ulotaront is coadministered with strong CYP2D6 inhibitors or administered to CYP2D6 poor metabolizers should not be necessary.

Ulotaront: review of preliminary evidence for the efficacy and safety of a TAAR1 agonist in schizophrenia

Ulotaront is a trace amine-associated receptor 1 (TAAR1) agonist in Phase 3 clinical development for the treatment of schizophrenia. Ulotaront was discovered through a unique, target-agnostic approach optimized to identify drug candidates lacking D2 and 5-HT2A receptor antagonism, while demonstrating an antipsychotic-like phenotypic profile in vivo. The mechanism of action (MOA) of ulotaront is thought to be mediated by agonism at TAAR1 and serotonin 5-HT1A receptors. Ulotaront has completed two Phase 2 trials (4-week acute study and 26-week open-label extension) which led to Breakthrough Therapy Designation from the US Food and Drug Administration for the treatment of schizophrenia. In the double-blind, placebo-controlled, acute study, ulotaront was associated with significant (p < 0.001) improvement in Positive and Negative Syndrome Scale (PANSS) total score (effect size [ES]: 0.45), with improvements vs. placebo also observed across secondary endpoints. Post-hoc analyses of the acute trial revealed additional evidence to support the effect of ulotaront on negative symptoms. In the 4-week study, ulotaront was well-tolerated, with an incidence of adverse events (AEs) numerically lower compared to placebo (45.8% vs. 50.4%; with a number needed to harm [NNH] for individual ulotaront AEs all > 40). The open-label extension demonstrated further improvement across schizophrenia symptoms and confirmed the tolerability of ulotaront, with a 6-month completion rate of 67%. Based on current data, ulotaront shows potential to be a first-in-class TAAR1 agonist for the treatment of schizophrenia with a safety and efficacy profile distinct from current antipsychotics.

Effects of ulotaront on brain circuits of reward, working memory, and emotion processing in healthy volunteers with high or low schizotypy

Ulotaront, a trace amine-associated receptor 1 (TAAR1) and serotonin 5-HT1A receptor agonist without antagonist activity at dopamine D2 or the serotonin 5-HT2A receptors, has demonstrated efficacy in the treatment of schizophrenia. Here we report the phase 1 translational studies that profiled the effect of ulotaront on brain responses to reward, working memory, and resting state connectivity (RSC) in individuals with low or high schizotypy (LS or HS). Participants were randomized to placebo (n = 32), ulotaront (50 mg; n = 30), or the D2 receptor antagonist amisulpride (400 mg; n = 34) 2 h prior to functional magnetic resonance imaging (fMRI) of blood oxygen level-dependent (BOLD) responses to task performance. Ulotaront increased subjective drowsiness, but reaction times were impaired by less than 10% and did not correlate with BOLD responses. In the Monetary Incentive Delay task (reward processing), ulotaront significantly modulated striatal responses to incentive cues, induced medial orbitofrontal responses, and prevented insula activation seen in HS subjects. In the N-Back working memory task, ulotaront modulated BOLD signals in brain regions associated with cognitive impairment in schizophrenia. Ulotaront did not show antidepressant-like biases in an emotion processing task. HS had significantly reduced connectivity in default, salience, and executive networks compared to LS participants and both drugs reduced this difference. Although performance impairment may have weakened or contributed to the fMRI findings, the profile of ulotaront on BOLD activations elicited by reward, memory, and resting state is compatible with an indirect modulation of dopaminergic function as indicated by preclinical studies. This phase 1 study supported the subsequent clinical proof of concept trial in people with schizophrenia.Clinical trial registration: Registry# and URL: ClinicalTrials.gov NCT01972711, https://clinicaltrials.gov/ct2/show/NCT01972711.

Unlocking the Therapeutic Potential of Ulotaront as a Trace Amine-Associated Receptor 1 Agonist for Neuropsychiatric Disorders

All antipsychotics currently used in clinic block D2 dopamine receptors. Trace amine-associated receptor 1 is emerging as a new therapeutic target for schizophrenia and several other neuropsychiatric disorders. SEP-363856 (International Nonproprietary Name: Ulotaront) is an investigational antipsychotic drug with a novel mechanism of action that does not involve antagonism of dopamine D2 receptors. Ulotaront is an agonist of trace amine-associated receptor 1 and serotonin 5-HT1A receptors, but can modulate dopamine neurotransmission indirectly. In 2019, the United States Food and Drug Administration granted Breakthrough Therapy Designation for ulotaront for the treatment of schizophrenia. Phase 2 clinical studies indicated that ulotaront can reduce both positive and negative symptoms of schizophrenia without causing the extrapyramidal or metabolic side effects that are inherent to most currently used antipsychotics. At present, it is in phase 3 clinical development for the treatment of schizophrenia and is expected to be introduced into clinical practice in 2023-2024. Clinical studies evaluating the potential efficacy of ulotaront in Parkinson's disease psychosis, generalized anxiety disorder, and major depressive disorder have also been started. The aim of this scoping review is to summarize all currently available preclinical and clinical evidence on the utility of ulotaront in the treatment of schizophrenia. Here, we show the main characteristics and distinctive features of this drug. Perspectives and limitations on the potential use of ulotaront in the pharmacotherapy of several other neuropsychiatric disorders are also discussed.

A multicenter, double-blind, placebo-controlled, randomized, Phase 1b crossover trial comparing two doses of ulotaront with placebo in the treatment of narcolepsy-cataplexy

BACKGROUND

Ulotaront (SEP-363856) is a novel agonist at trace amine-associated receptor 1 and serotonin 5-HT_1A receptors in clinical development for the treatment of schizophrenia. Previous studies demonstrated ulotaront suppresses rapid eye movement (REM) sleep in both rodents and healthy volunteers. We assessed acute and sustained treatments of ulotaront on REM sleep and symptoms of cataplexy and alertness in subjects with narcolepsy-cataplexy.

METHODS

In a multicenter, double-blind, placebo-controlled, randomized, 3-way crossover study, ulotaront was evaluated in 16 adults with narcolepsy-cataplexy. Two oral doses of ulotaront (25 mg and 50 mg) were administered daily for 2 weeks and compared with matching placebo (6-treatment sequence, 3-period, 3-treatment).

RESULTS

Acute treatment with both 25 mg and 50 mg of ulotaront reduced minutes spent in nighttime REM compared to placebo. A sustained 2-week administration of both doses of ulotaront reduced the mean number of short-onset REM periods (SOREMPs) during daytime multiple sleep latency test (MSLT) compared to placebo. Although cataplexy events decreased from the overall mean baseline during the 2-week treatment period, neither dose of ulotaront statistically separated from placebo (p = 0.76, 25 mg; p = 0.82, 50 mg), and no significant improvement in patient and clinician measures of sleepiness from baseline to end of the 2-week treatment period occurred in any treatment group.

CONCLUSIONS

Acute and sustained treatment with ulotaront reduced nighttime REM duration and daytime SOREMPs, respectively. The effect of ulotaront on suppression of REM did not demonstrate a statistical or clinically meaningful effect in narcolepsy-cataplexy.

REGISTRATION

ClinicalTrials.gov identifier: NCT05015673.

Efficacy, safety, and tolerability of ulotaront (SEP-363856, a trace amine-associated receptor 1 agonist) for the treatment of schizophrenia and other mental disorders with similar pathophysiology: a systematic review of preclinical and clinical trials

INTRODUCTION

Schizophrenia is a mental illness that can disrupt emotions, perceptions, cognition, and reduce quality of life. The classical approach to treat schizophrenia uses typical and atypical antipsychotics; however, limitations include low efficacy in mitigating negative symptoms and cognitive dysfunctions, and a range of adverse effects. Evidence has accumulated on trace amine-associated receptor 1 (TAAR1) as a novel therapeutic target for treating schizophrenia. This systematic review investigates the available evidence on a TAAR1 agonist, ulotaront, as a treatment for schizophrenia.

METHODS

A systematic search was conducted on PubMed/MEDLINE, and Ovid databases for English-published articles from inception to December 18, 2022. Literature focusing on the association between ulotaront and schizophrenia were evaluated based on an inclusion/exclusion criterion. Selected studies were assessed for risk of bias, using Cochrane Collaboration tool, and summarized in a table to generate discussion topics.

RESULTS

Three clinical, two comparative, and five preclinical studies examining ulotaront's pharmacology, tolerability and safety, and/or efficacy were identified. Results indicate that ulotaront has a differing adverse effects profile from other antipsychotics, may mitigate metabolic-related adverse effects commonly associated with antipsychotics, and may be effective for treating positive and negative symptoms.

CONCLUSIONS

Findings from available literature present ulotaront as a potential and promising alternative treatment method for schizophrenia. Despite this, our results were limited due to lack of clinical trials on ulotaront's long-term efficacy and mechanisms of action. Future research should focus on these limitations to elucidate ulotaront's efficacy and safety for the treatment of schizophrenia and other mental disorders with similar pathophysiology.

Calcium, magnesium, potassium, and sodium oxybates oral solution for cataplexy or excessive daytime sleepiness associated with narcolepsy

INTRODUCTION

Lower-sodium oxybate (LXB) is a novel formulation that is approved by the US Food and Drug Administration (FDA) to treat cataplexy and excessive daytime sleepiness (EDS) in adult patients and children ≥ 7 years with narcolepsy. LXB contains 92 percent less sodium than sodium oxybate (SXB), which adds 550-1640 mg of sodium/day at usual doses of 3-9 grams per day. The FDA has declared LXB to be clinically superior to SXB due to greater safety by reducing the chronic sodium load. Narcolepsy patients have high comorbidities for hypertension and cardiovascular disease, conditions which can be adversely affected by high sodium intake.

AREAS COVERED

This drug review discusses narcolepsy, current and upcoming pharmacotherapy, and LXB chemistry, pharmacodynamics, pharmacokinetics, and metabolism. Published results from LXB's phase 1 studies, a phase 3 study, and 2 post-marketing studies are reviewed. Databases searched included Pubmed, Google Scholar, Lexi-Comp, Scopus, Science, and Ovid.

EXPERT OPINION

LXB is efficacious in treating daytime sleepiness and cataplexy in adults and children ≥ 7 years with narcolepsy. Using LXB instead of SXB formulations may benefit narcolepsy patients with cardiovascular comorbidities and hypertension, but long-term studies are needed to prove it.

Experimental Medicine Approaches in Early-Phase CNS Drug Development

Traditionally, Phase 1 clinical trials were largely conducted in healthy normal volunteers and focused on collection of safety, tolerability, and pharmacokinetic data. However, in the CNS therapeutic area, with more drugs failing in later phase development, Phase 1 trials have undergone an evolution that includes incorporation of novel approaches involving novel study designs, inclusion of biomarkers, and early inclusion of patients to improve the pharmacologic understanding of novel CNS-active compounds early in clinical development with the hope of improving success in later phase pivotal trials. In this chapter, the authors will discuss the changing landscape of Phase 1 clinical trials in CNS, including novel trial methodology, inclusion of pharmacodynamic biomarkers, and experimental medicine approaches to inform early decision-making in clinical development.

Treatment with the novel TAAR1 agonist ulotaront is associated with reductions in quantitative polysomnographic REM sleep without atonia in healthy human subjects: Results of a post-hoc analysis

BACKGROUND

Isolated REM sleep behavior disorder (RBD) is a potentially injurious parasomnia lacking an established treatment. Ulotaront is a trace amine-associated receptor 1 (TAAR1) agonist with 5-HT_1A receptor agonist activity that has demonstrated efficacy in patients with schizophrenia. In a single dose challenge study in humans, ulotaront 50 mg demonstrated significant REM suppressant effects. We now report post-hoc exploratory analyses designed to evaluate the effect of ulotaront on quantitative REM sleep without atonia (RSWA).

METHODS

Young healthy adult men (ages 19-35) were randomized to double-blind, cross-over treatment (after 7-day wash-out) with single doses of ulotaront (50 mg or 10 mg) versus placebo followed by polysomnography (PSG) on each of the nights following treatment. Quantitative RSWA was analyzed in a blinded fashion using established visual and automated methods.

RESULTS

Subjects received 50 mg (n = 11) or 10 mg (n = 9) of ulotaront. Treatment with ulotaront 50 mg was associated with lower RSWA (p < 0.05), with greatest RSWA reduction (vs. placebo) observed in subjects with RSWA levels above the mean on the baseline night. RSWA levels were similar between treatment with ulotaront 10 mg and placebo.

CONCLUSION

Treatment with ulotaront 50 mg (but not 10 mg) was associated with reductions in RSWA levels in healthy subjects, especially in subjects with higher baseline RSWA levels, providing proof-of-concept for ulotaront efficacy in reducing RSWA levels. However, whether ulotaront might have efficacy as a treatment for human RBD awaits double-blind trials with ulotaront in clinical RBD populations.

Genetic and neural mechanisms of sleep disorders in children with autism spectrum disorder: a review

Background

The incidence of sleep disorders in children with autism spectrum disorder (ASD) is very high. Sleep disorders can exacerbate the development of ASD and impose a heavy burden on families and society. The pathological mechanism of sleep disorders in autism is complex, but gene mutations and neural abnormalities may be involved.

Methods

In this review, we examined literature addressing the genetic and neural mechanisms of sleep disorders in children with ASD. The databases PubMed and Scopus were searched for eligible studies published between 2013 and 2023.

Results

Prolonged awakenings of children with ASD may be caused by the following processes. Mutations in the MECP2, VGAT and SLC6A1 genes can decrease GABA inhibition on neurons in the locus coeruleus, leading to hyperactivity of noradrenergic neurons and prolonged awakenings in children with ASD. Mutations in the HRH1, HRH2, and HRH3 genes heighten the expression of histamine receptors in the posterior hypothalamus, potentially intensifying histamine's ability to promote arousal. Mutations in the KCNQ3 and PCDH10 genes cause atypical modulation of amygdala impact on orexinergic neurons, potentially causing hyperexcitability of the hypothalamic orexin system. Mutations in the AHI1, ARHGEF10, UBE3A, and SLC6A3 genes affect dopamine synthesis, catabolism, and reuptake processes, which can elevate dopamine concentrations in the midbrain. Secondly, non-rapid eye movement sleep disorder is closely related to the lack of butyric acid, iron deficiency and dysfunction of the thalamic reticular nucleus induced by PTCHD1 gene alterations. Thirdly, mutations in the HTR2A, SLC6A4, MAOA, MAOB, TPH2, VMATs, SHANK3, and CADPS2 genes induce structural and functional abnormalities of the dorsal raphe nucleus (DRN) and amygdala, which may disturb REM sleep. In addition, the decrease in melatonin levels caused by ASMT, MTNR1A, and MTNR1B gene mutations, along with functional abnormalities of basal forebrain cholinergic neurons, may lead to abnormal sleep-wake rhythm transitions.

Conclusion

Our review revealed that the functional and structural abnormalities of sleep-wake related neural circuits induced by gene mutations are strongly correlated with sleep disorders in children with ASD. Exploring the neural mechanisms of sleep disorders and the underlying genetic pathology in children with ASD is significant for further studies of therapy.

Ulotaront: a TAAR1/5-HT1A agonist in clinical development for the treatment of schizophrenia

INTRODUCTION

Current antipsychotics are postsynaptic dopamine-2(D₂) receptor blockers, which often, but not always, effectively improve acute psychotic symptoms and prevent relapse in schizophrenia and other severe mental disorders, but are associated with various side effects, including parkinsonism, akathisia, sedation/somnolence, and cardiometabolic alterations. Furthermore, the efficacy of current antipsychotics for negative and cognitive symptoms in schizophrenia is limited. Ulotaront is a novel trace-amine-associated receptor-1(TAAR1) agonist with serotonin-1A receptor agonist activity, and without postsynaptic D2-receptor antagonism. Phase 2 clinical data for ulotaront in patients with acutely exacerbated schizophrenia are promising regarding the potential improvement in positive, negative, and depressive symptoms.

AREAS COVERED

An overview of the pharmacokinetic and pharmacodynamic properties of ulotaront is given. Summary of clinical efficacy and safety/tolerability from Phase 1/2-trials, and of ongoing Phase 3-trials, is also given.

EXPERT OPINION

Ulotaront is a promising agent for the treatment of schizophrenia with an apparent benign safety profile, which might provide a much-needed new and different treatment option for various domains of schizophrenia. Data from larger Phase 3-trials, including for relapse prevention, schizophrenia subdomains, and in adolescents, are awaited. If ongoing Phase 3-trials in adults are successful, further research on combination regimens with existing antipsychotics, and in treatment-resistant schizophrenia as well as in mood disorders would be desirable.

A randomized placebo-controlled double-blind study of dexmedetomidine on postoperative sleep quality in patients with endoscopic sinus surgery

Background

Postoperative sleep disorder is common and may cause aggravated postoperative pain, delirium, and poor prognosis. We accessed the effect of intraoperative intravenous dexmedetomidine on postoperative sleep quality in patients with endoscopic sinus surgery. 

Methods

This single-center, double-blind, placebo-controlled randomized clinical trial enrolled a total of 110 participants aged 18 years to 65 years who were scheduled to receive endoscopic sinus surgery. Placebo (normal saline) or dexmedetomidine infusion (load dose 0.5 μg kg⁻¹ over 10 min, followed by maintenance dose 0.2 ug kg⁻¹ h⁻¹) during surgery. The primary outcome was postoperative sleep quality. Secondary outcomes were postoperative Ramsay sedation scores, Visual Analog Scale (VAS) scores, serum cortisol, 5-hydroxytryptamine (5-HT) and hypocretin, delirium, and postoperative nausea and vomiting (PONV).

Results

Among enrolled 110 patients, 55 were randomized to administer intraoperative dexmedetomidine and placebo. In total, 14 patients (7 in each group) were excluded because of protocol deviations, and 96 patients (48 in each group) were included in the per-protocol analysis. The dexmedetomidine group had a significantly higher sleep efficiency index(SEI) (66.85[3.00] vs 65.38[3.58]), the ratio of rapid eye movement sleep to total sleep(REM)(13.63[1.45] vs 12.38[2.11]) and lower arousal index (AI) (7.20[1.00] vs 8.07[1.29]), higher Ramsay sedation score at post-operation 1 h, 12 h point, lower VAS scores at post-operation 1 h, 12 h, 24 h point, lower cortisol, higher 5-HT and hypocretin in serum than the placebo group.

Conclusion

In this randomized clinical trial, dexmedetomidine can improve the sleep quality of patients undergoing endoscopic sinus surgery. These results suggest that this therapy may be a viable strategy to enhance postoperative sleep quality in patients with endoscopic sinus surgery.

Trial registration

The study was approved by the Bethune International Peace Hospital Ethics Committee (2021-KY-129) and registered in the Chinese Clinical Trial Registry (ChiCTR2100051598, 28/09/2021). 

The Potential Antidepressant Action of Duloxetine Co-Administered with the TAAR1 Receptor Agonist SEP-363856 in Mice

Here, we explored the possible interaction between duloxetine and SEP-363856 (SEP-856) in depression-related reactions. The results showed that oral administration of duloxetine showed powerful antidepressant-like effects in both the forced swimming test (FST) and the suspension tail test (TST). SEP-856 orally administered alone also exerted an antidepressant-like effect in FST and TST, especially at doses of 0.3, 1, and 10 mg/kg. In addition, duloxetine (15 mg/kg) and SEP-856 (15 mg/kg) both showed antidepressant-like effects in the sucrose preference test (SPT). Most importantly, in the above experiments, compared with duloxetine alone, the simultaneous use of duloxetine and SEP-856 caused a more significant antidepressant-like effect. It is worth noting that doses of drug combination in FST and TST did not change the motor activities of mice in the open-field test (OFT). Thus, duloxetine and SEP-856 seem to play a synergistic role in regulating depression-related behaviors and might be beneficial for refractory depression.

Ulotaront: A TAAR1 Agonist for the Treatment of Schizophrenia

Ulotaront (SEP-363856) is a trace-amine associated receptor 1 (TAAR1) agonist with 5-HT1A receptor agonist activity in Phase 3 clinical development, with FDA Breakthrough Therapy Designation, for the treatment of schizophrenia. TAAR1 is a G-protein-coupled receptor (GPCR) that is expressed in cortical, limbic, and midbrain monoaminergic regions. It is activated by endogenous trace amines, and is believed to play an important role in modulating dopaminergic, serotonergic, and glutamatergic circuitry. TAAR1 agonism data are reported herein for ulotaront and its analogues in comparison to endogenous TAAR1 agonists. In addition, a human TAAR1 homology model was built around ulotaront to identify key interactions and attempt to better understand the scaffold-specific TAAR1 agonism structure–activity relationships.

A sensitive LC-MS/MS method for simultaneous quantification of ulotaront and its N-desmethyl metabolite in human plasma and application to a clinical study

Ulotaront (SEP-363856) is a novel non-D2-receptor-binding agent under development for the treatment of patients with schizophrenia. A highly sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method with lower limit of quantitation of 0.0200 ng/mL (i.e. 20.0 pg/mL) was successfully developed and validated for the simultaneous quantitation of ulotaront and its N-desmethyl metabolite (M11A) in human plasma. Plasma samples were extracted by solid phase extraction with Oasis MCX 96-well plate, followed by a reversed phase LC separation coupled with MS/MS detection in positive mode (m/z 184.1 → 135.0 for ulotaront and 170.1 → 135.0 for M11A). Stable isotope-labeled compounds SEP-363856-d₃ and M11A-d₄ were used as internal standards (IS) for corresponding analytes. The validated calibration curve range was 0.0200-20.0 ng/mL for both analytes using a 0.200 mL plasma. Extraction recoveries were found to be 75.7% and 75.1% for ulotaront and IS1, and 82.7% and 83.9% for M11A and IS2, respectively. Frozen plasma samples were confirmed to be stable for up to 730 days at both -20 °C and -70 °C. The validated method has been successfully used to evaluate the pharmacokinetics (PK) of ulotaront and M11A in clinical studies. The application to the first-in-human PK study (single ascending dose) presented in this work demonstrated that ulotaront exhibited near dose proportionality for both C_max (maximum concentration) and AUC (area under the curve) over the dose range from 5 to 125 mg. M11A was found as a minor metabolite with an exposure of about 2-3% of the parent compound.

Safety and effectiveness of ulotaront (SEP-363856) in schizophrenia: results of a 6-month, open-label extension study

Ulotaront, a trace amine-associated receptor 1 (TAAR1) and serotonin 5-HT1A receptors agonist, has demonstrated efficacy in the treatment of patients with an acute exacerbation of schizophrenia in a 4-week, double-blind, placebo-controlled study. The aim of this 26-week open-label extension study was to evaluate the safety and effectiveness of ulotaront (25/50/75 mg/d) in patients who completed the initial 4-week study. Of the 193 4-week completers, 157 patients (81.3%) continued into the open-label extension study; 66.9% were completers. Among all extension phase patients, treatment with ulotaront was associated with minimal changes in body weight (mean [SD] change from double-blind baseline: −0.3 [3.7] kg), cholesterol (median change, −2.0 mg/dL), triglycerides (median, −5.0 mg/dL), and prolactin (female, median, −3.4 ng/mL; male, median, −2.7 ng/mL). Movement disorder scales showed no extrapyramidal effects. Twenty-six weeks of extension phase treatment was associated with a mean (95% CI) observed change from open-label baseline in the PANSS total score of −22.6 (−25.6, −19.6; effect size, 1.46), and a mean (95% CI) change in the CGI-Severity score of −1.0 (−1.2, −0.8; effect size, 1.07). Long-term treatment with the TAAR1 agonist ulotaront, in the daily dose range of 25–75 mg, was characterized by a relatively high completion rate, an adverse event profile notable for the absence of extrapyramidal-related adverse effects, a low liability for adverse weight and metabolic effects, and no effect on prolactin levels. Additional studies are needed to further confirm the long-term efficacy and safety of ulotaront.

Safety and effectiveness of ulotaront (SEP-363856) in schizophrenia: results of a 6-month, open-label extension study

Ulotaront, a trace amine-associated receptor 1 (TAAR1) and serotonin 5-HT1A receptors agonist, has demonstrated efficacy in the treatment of patients with an acute exacerbation of schizophrenia in a 4-week, double-blind, placebo-controlled study. The aim of this 26-week open-label extension study was to evaluate the safety and effectiveness of ulotaront (25/50/75 mg/d) in patients who completed the initial 4-week study. Of the 193 4-week completers, 157 patients (81.3%) continued into the open-label extension study; 66.9% were completers. Among all extension phase patients, treatment with ulotaront was associated with minimal changes in body weight (mean [SD] change from double-blind baseline: -0.3 [3.7] kg), cholesterol (median change, -2.0 mg/dL), triglycerides (median, -5.0 mg/dL), and prolactin (female, median, -3.4 ng/mL; male, median, -2.7 ng/mL). Movement disorder scales showed no extrapyramidal effects. Twenty-six weeks of extension phase treatment was associated with a mean (95% CI) observed change from open-label baseline in the PANSS total score of -22.6 (-25.6, -19.6; effect size, 1.46), and a mean (95% CI) change in the CGI-Severity score of -1.0 (-1.2, -0.8; effect size, 1.07). Long-term treatment with the TAAR1 agonist ulotaront, in the daily dose range of 25-75 mg, was characterized by a relatively high completion rate, an adverse event profile notable for the absence of extrapyramidal-related adverse effects, a low liability for adverse weight and metabolic effects, and no effect on prolactin levels. Additional studies are needed to further confirm the long-term efficacy and safety of ulotaront.

Therapeutic Potential of TAAR1 Agonists in Schizophrenia: Evidence from Preclinical Models and Clinical Studies

Trace amine-associated receptor 1 (TAAR1) has emerged as a promising therapeutic target for neuropsychiatric disorders due to its ability to modulate monoaminergic and glutamatergic neurotransmission. In particular, agonist compounds have generated interest as potential treatments for schizophrenia and other psychoses due to TAAR1-mediated regulation of dopaminergic tone. Here, we review unmet needs in schizophrenia, the current state of knowledge in TAAR1 circuit biology and neuropharmacology, including preclinical behavioral, imaging, and cellular evidence in glutamatergic, dopaminergic and genetic models linked to the pathophysiology of psychotic, negative and cognitive symptoms. Clinical trial data for TAAR1 drug candidates are reviewed and contrasted with antipsychotics. The identification of endogenous TAAR1 ligands and subsequent development of small-molecule agonists has revealed antipsychotic-, anxiolytic-, and antidepressant-like properties, as well as pro-cognitive and REM-sleep suppressing effects of TAAR1 activation in rodents and non-human primates. Ulotaront, the first TAAR1 agonist to progress to randomized controlled clinical trials, has demonstrated efficacy in the treatment of schizophrenia, while another, ralmitaront, is currently being evaluated in clinical trials in schizophrenia. Coupled with the preclinical findings, this provides a rationale for further investigation and development of this new pharmacological class for the treatment of schizophrenia and other psychiatric disorders.

Depicting Safety Profile of TAAR1 Agonist Ulotaront Relative to Reactions Anticipated for a Dopamine D2-Based Pharmacological Class in FAERS

Background and Objectives

In clinical trials, the safety of drugs is summarized by the incidence of adverse events, while post-marketing reporting systems use disproportionate reporting of adverse drug reactions. Here, we propose a method to evaluate the novelty of a safety profile of a drug in a new class (in clinical trials), against that of those already on the market (using pharmacovigilance data).

Methods

Through Bayesian disproportionality analyses of the US Food and Drug Administration Adverse Event Reporting System (FAERS) data, we identified and ranked Preferred Terms for a pool of 30 antipsychotics. Adverse event rates in randomized, double-blind, placebo-controlled schizophrenia clinical trials were summarized by their class specificity. One study (N = 245) of the trace amine-associated receptor 1 (TAAR1) agonist ulotaront (SEP-363856) was compared with five studies of dopamine D2 receptor-based antipsychotics lurasidone (N = 1041), quetiapine (N = 119), olanzapine (N = 122), and placebo (N = 504).

Results

In clinical trials of antipsychotics, cumulative rates for adverse events at and above a threshold of disproportional reporting (Empirical Bayes Geometric Mean 50 > 3 in FAERS) were 52%, 42%, and 60% for lurasidone, quetiapine, and olanzapine, respectively, indicating that over half of the adverse events reported in clinical trials of an atypical antipsychotic are class-specific risks. In contrast, in the clinical trial of ulotaront, the cumulative rate was 23%, indicating a lower rate of antipsychotic class-specific risk.

Conclusions

These results demonstrate a novel approach to summarize adverse events in clinical trials, where the cumulative burden of class-specific risks describes the emerging safety profile of a new drug in clinical development, relative to reactions anticipated for drugs in an established pharmacological class.

ClinicalTrials.gov Identifiers

NCT0296938, NCT00088634, NCT00549718, NCT00615433, NCT00790192.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40261-021-01094-7.

TAAR1 Expression in Human Macrophages and Brain Tissue: A Potential Novel Facet of MS Neuroinflammation

TAAR1 is a neuroregulator with emerging evidence suggesting a role in immunomodulation. Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the central nervous system. Here, we investigate TAAR1 expression in human primary monocytes, peripherally-derived macrophages, and MS brain tissue. RT-qPCR was used to assess TAAR1 levels in MS monocytes. Using a previously validated anti-human TAAR1 antibody and fluorescence microscopy, TAAR1 protein was visualized in lipopolysaccharide-stimulated or basal human macrophages, as well as macrophage/microglia populations surrounding, bordering, and within a mixed active/inactive MS lesion. In vivo, TAAR1 mRNA expression was significantly lower in MS monocytes compared to age- and sex-matched healthy controls. In vitro, TAAR1 protein showed a predominant nuclear localization in quiescent/control macrophages with a shift to a diffuse intracellular distribution following lipopolysaccharide-induced activation. In brain tissue, TAAR1 protein was predominantly expressed in macrophages/microglia within the border region of mixed active/inactive MS lesions. Considering that TAAR1-mediated anti-inflammatory effects have been previously reported, decreased mRNA in MS patients suggests possible pathophysiologic relevance. A shift in TAAR1 localization following pro-inflammatory activation suggests its function is altered in pro-inflammatory states, while TAAR1-expressing macrophages/microglia bordering an MS lesion supports TAAR1 as a novel pharmacological target in cells directly implicated in MS neuroinflammation.

Biomolecular Evaluation of Piceatannol's Effects in Counteracting the Senescence of Mesenchymal Stromal Cells: A New Candidate for Senotherapeutics?

Several investigations on senescence and its causative role in aging have underscored the importance of developing senotherapeutics, a field focused on killing senescent cells and/or preventing their accumulation within tissues. Using polyphenols in counteracting senescence may facilitate the development of senotherapeutics given their presence in the human diet, their confirmed tolerability and absence of severe side effects, and their role in preventing senescence and inducing the death of senescent cells. Against that background, we evaluated the effect of piceatannol, a natural polyphenol, on the senescence of mesenchymal stromal cells (MSCs), which play a key role in the body's homeostasis. Among our results, piceatannol reduced the number of senescent cells both after genotoxic stress that induced acute senescence and in senescent replicative cultures. Such senotherapeutics activity, moreover, promoted the recovery of cell proliferation and the stemness properties of MSCs. Altogether, our findings demonstrate piceatannol's effectiveness in counteracting senescence by targeting its associated pathways and detecting and affecting P53-dependent and P53-independent senescence. Our study thus suggests that, given piceatannol's various mechanisms to accomplish its pleiotropic activities, it may be able to counteract any senescent phenotypes.

Population pharmacokinetic analysis of ulotaront in subjects with schizophrenia

Ulotaront (SEP-363856) is a trace amine-associated receptor 1 agonist with 5-HT1A agonist activity in phase III development for the treatment of schizophrenia. The efficacy of ulotaront is not mediated by blockade of D2 or 5-HT2A receptors. The aim of this study was to evaluate the population pharmacokinetics (PopPKs) of ulotaront in adult subjects using pooled data from seven phase I studies, one phase II acute study, and one 6-month extension study. Single and multiple (up to 7 days) oral doses (5-150 mg/day) were studied in both healthy adult subjects (with intensive serial plasma sampling) and adult patients with schizophrenia (some with intensive and some with sparse plasma sampling). Ulotaront was well-absorbed and exhibited dose-proportionality in doses ranging from 10 to 100 mg, in mean maximum concentration, area under the concentration-time curve, and minimum concentration. Moderate interindividual variability was observed in concentration-time profiles. The estimated median time to maximal concentration was 2.8 h and the median effective half-life was 7 h, corresponding to an exposure accumulation ratio of 1.10 at steady-state with daily dosing. There was no indication of time-dependent changes in PKs after up to 12 weeks of daily dose administration. No clinically meaningful effects on ulotaront PK parameters were observed based on race, age, sex, formulation (capsule or tablet), or clinical status (healthy volunteer vs. patient with schizophrenia); body weight was the only meaningful covariate.