TAK-861, a potent, orally available orexin receptor 2-selective agonist, produces wakefulness in monkeys and improves narcolepsy-like phenotypes in mouse models.

Narcolepsy type 1 (NT1) is associated with severe loss of orexin neurons and characterized by symptoms including excessive daytime sleepiness and cataplexy. Current medications indicated for NT1 often show limited efficacy, not addressing the full spectrum of symptoms, demonstrating a need for novel drugs. We discovered a parenteral orexin receptor 2 (OX2R) agonist, danavorexton, and an orally available OX2R agonist, TAK-994; both improving NT1 phenotypes in mouse models and individuals with NT1. However, danavorexton has limited oral availability and TAK-994 has a risk of off-target liver toxicity. To avoid off-target-based adverse events, a highly potent molecule with low effective dose is preferred. Here, we show that a novel OX2R-selective agonist, TAK-861 [N-{(2S,3R)-4,4-Difluoro-1-(2-hydroxy-2-methylpropanoyl)-2-[(2,3',5'-trifluoro[1,1'-biphenyl]-3-yl)methyl]pyrrolidin-3-yl}ethanesulfonamide], activates OX2R with a half-maximal effective concentration of 2.5 nM and promotes wakefulness at 1 mg/kg in mice and monkeys, suggesting ~ tenfold higher potency and lower effective dosage than TAK-994. Similar to TAK-994, TAK-861 substantially ameliorates wakefulness fragmentation and cataplexy-like episodes in orexin/ataxin-3 and orexin-tTA;TetO DTA mice (NT1 mouse models). Compared with modafinil, TAK-861 induces highly correlated brain-wide neuronal activation in orexin-tTA;TetO DTA mice, suggesting efficient wake-promoting effects. Thus, TAK-861 has potential as an effective treatment for individuals with hypersomnia disorders including narcolepsy, potentially with a favorable safety profile.

Effects of an OX2R agonist on migration and removal of tau from mouse brain.

Pathological proteins including tau are produced in neurons and released into interstitial fluid (ISF) in a neural activity-dependent manner during wakefulness. Pathological proteins in ISF can be removed from the brain via the glymphatic pathway during nighttime. Thus, in individuals with Alzheimer's disease (AD) that have dysregulated sleep/wake rhythm, application of orexin receptor 2 (OX2R) agonists during daytime could recover the efflux of pathological proteins to ISF and indirectly promote the glymphatic pathway by improving the quality of nighttime sleep after proper daytime arousal, resulting in increased removal of these proteins from the brain. We investigated this hypothesis using OX-201, a novel OX2R-selective agonist with a 50% effective concentration of 8.0 nM. Diurnal rhythm of tau release into hippocampal ISF correlated well with neuronal activity and wakefulness in wild-type mice. In both wild-type and human P301S tau transgenic mice, OX-201 induced wakefulness and promoted tau release into hippocampal ISF. Human P301S tau transgenic mice, tested under our conditions, showed longer wakefulness time, which differs from individuals with AD. OX-201 treatment over 2 months did not alter hippocampal tau levels. Although further studies are required, at a minimum OX2R agonists may not exacerbate tau accumulation in individuals with tauopathy, including AD.

Orexin receptor 2 agonist activates diaphragm and genioglossus muscle through stimulating inspiratory neurons in the pre-Bötzinger complex, and phrenic and hypoglossal motoneurons in rodents.

Orexin-mediated stimulation of orexin receptors 1/2 (OX[1/2]R) may stimulate the diaphragm and genioglossus muscle via activation of inspiratory neurons in the pre-Bötzinger complex, which are critical for the generation of inspiratory rhythm, and phrenic and hypoglossal motoneurons. Herein, we assessed the effects of OX2R-selective agonists TAK-925 (danavorexton) and OX-201 on respiratory function. In in vitro electrophysiologic analyses using rat medullary slices, danavorexton and OX-201 showed tendency and significant effect, respectively, in increasing the frequency of inspiratory synaptic currents of inspiratory neurons in the pre-Bötzinger complex. In rat medullary slices, both danavorexton and OX-201 significantly increased the frequency of inspiratory synaptic currents of hypoglossal motoneurons. Danavorexton and OX-201 also showed significant effect and tendency, respectively, in increasing the frequency of burst activity recorded from the cervical (C3-C5) ventral root, which contains axons of phrenic motoneurons, in in vitro electrophysiologic analyses from rat isolated brainstem-spinal cord preparations. Electromyogram recordings revealed that intravenous administration of OX-201 increased burst frequency of the diaphragm and burst amplitude of the genioglossus muscle in isoflurane- and urethane-anesthetized rats, respectively. In whole-body plethysmography analyses, oral administration of OX-201 increased respiratory activity in free-moving mice. Overall, these results suggest that OX2R-selective agonists enhance respiratory function via activation of the diaphragm and genioglossus muscle through stimulation of inspiratory neurons in the pre-Bötzinger complex, and phrenic and hypoglossal motoneurons. OX2R-selective agonists could be promising drugs for various conditions with respiratory dysfunction.

Effects of the orexin receptor 2 agonist danavorexton on emergence from general anaesthesia and opioid-induced sedation, respiratory depression, and analgesia in rats and monkeys.

BACKGROUND: Delayed emergence from general anaesthesia, opioid-induced sedation, and opioid-induced respiratory depression is associated with perioperative complications. We characterised the preclinical effects of the orexin receptor 2 (OX2R)-selective agonist danavorexton (TAK-925) on emergence from anaesthesia and reversal of fentanyl-induced sedation, respiratory depression, and analgesia. METHODS: Emergence from isoflurane- or propofol-induced anaesthesia and fentanyl-induced sedation were investigated by righting reflex, rotarod, and electroencephalography in rats or monkeys. Fentanyl-induced respiratory depression was assessed by arterial blood gas analysis and whole-body plethysmography in rats and monkeys. Analgesia was evaluated using formalin- and skin incision-induced pain models in rats. RESULTS: Danavorexton shortened emergence from isoflurane- or propofol-induced anaesthesia and from fentanyl-induced sedation at 1 (P=0.005), 3 (P=0.006), and 3 mg kg-1 s.c. (P=0.022), respectively, by righting reflex in rats. Danavorexton (10 mg kg-1 s.c.) accelerated recovery from isoflurane-, propofol- and fentanyl-induced motor impairment in separate rotarod tests in rats (P=0.008, P=0.007, P=0.017, respectively), and reversed anaesthesia and fentanyl-induced delta-power increases. Danavorexton shortened emergence (return of righting reflex) from isoflurane- or propofol-induced anaesthesia at 1 (P=0.002) and 3 mg kg-1 (P=0.004), respectively, in cynomolgus monkeys. Danavorexton (10 mg kg-1 s.c.) reversed fentanyl-induced increase in Pco2 (P=0.006), and decrease in Po2 (P=0.015) and pH (P<0.001) in rats, and at 3 mg kg-1 s.c. reversed fentanyl-induced increase in Pco2 (P=0.007), and decrease in Po2 (P=0.013) and SO2 (P=0.036) in monkeys. Danavorexton increased minute volume and tidal volume in fentanyl-treated animals. Danavorexton at ≤10 mg kg-1 s.c. did not compromise fentanyl analgesia in rat formalin- and skin incision-induced pain models. CONCLUSIONS: Danavorexton promoted recovery from anaesthesia and fentanyl-induced sedation, and antagonised fentanyl-induced respiratory depression without compromising fentanyl analgesia.

The orexin receptor 2 (OX2R)-selective agonist TAK-994 increases wakefulness without affecting cerebrospinal fluid orexin levels in cynomolgus monkeys.

Orexin A (OX-A) and orexin B are neuropeptides produced in orexin neurons located in the lateral hypothalamus that exert multiple biological functions through the activation of orexin receptor 1 (OX1R) and orexin receptor 2 (OX2R) throughout the central nervous system. OX1R and OX2R have distinct functions: OX1R is involved in reward seeking, whereas OX2R has a pivotal role in sleep/wake regulation. OX2R-selective agonists are in development as novel therapeutic agents for the treatment of hypersomnia. However, their potential to induce orexin release, which may indirectly stimulate both OX1R and OX2R in vivo, is unclear. Herein, we assessed the effects of the OX2R-selective agonist TAK-994 on wakefulness and orexin release in monkeys. Oral administration of TAK-994 at 10 mg/kg in the beginning of the sleep phase (zeitgeber time [ZT] 12) significantly increased wakefulness time in monkeys but did not increase OX-A levels in monkey cisternal cerebrospinal fluid (CSF). Moreover, oral administration of TAK-994 (10 mg/kg) during the active phase (ZT1) did not increase OX-A levels in monkey CSF. These findings indicate that the OX2R agonist TAK-994 selectively activates OX2R in vivo and would not robustly induce spontaneous orexin release during the daytime or nighttime in monkeys.

TAK-994, a Novel Orally Available Brain-Penetrant Orexin 2 Receptor-Selective Agonist, Suppresses Fragmentation of Wakefulness and Cataplexy-Like Episodes in Mouse Models of Narcolepsy.

Loss of orexin neurons is associated with narcolepsy type 1 (NT1), which is characterized by multiple symptoms including excessive daytime sleepiness and cataplexy. Orexin 2 receptor (OX2R) knockout (KO) mice, but not orexin 1 receptor (OX1R) KO mice, show narcolepsy-like phenotypes, thus OX2R agonists are potentially promising for treating NT1. In fact, in early proof-of-concept studies, intravenous infusion of danavorexton, an OX2R-selective agonist, significantly increased wakefulness in individuals with NT1. However, danavorexton has limited oral availability. Here, we report pharmacological characteristics of a novel OX2R agonist, TAK-994 [N-{(2S,3S)-1-(2-hydroxy-2-methylpropanoyl)-2-[(2,3',5'-trifluorobiphenyl-3-yl)methyl]pyrrolidin-3-yl}methanesulfonamide sesquihydrate]. TAK-994 activated recombinant human OX2R (EC50 value of 19 nM) with > 700-fold selectivity against OX1R and activated OX2R-downstream signaling similar to those by orexin peptides in vitro. Oral administration of TAK-994 promoted wakefulness in normal mice but not in OX2R KO mice. TAK-994 also ameliorated narcolepsy-like symptoms in two mouse models of narcolepsy: orexin/ataxin-3 mice and orexin-tTA;TetO diphtheria toxin A mice. The wake-promoting effects of TAK-994 in orexin/ataxin-3 mice were maintained after chronic dosing for 14 days. These data suggest that overall in vitro and in vivo properties, except oral availability, are very similar between TAK-994 and danavorexton. Preclinical characteristics of TAK-994 shown here, together with upcoming clinical study results, can improve our understanding for orally available OX2R agonists as new therapeutic drugs for NT1 and other hypersomnia disorders. SIGNIFICANCE STATEMENT: Narcolepsy type 1 (NT1) is caused by a loss of orexin neurons, and thus an orexin 2 receptor (OX2R) agonist is considered to address the underlying pathophysiology of NT1. Oral administration of TAK-994, a novel OX2R agonist, promoted wakefulness in normal mice, but not in OX2R knockout mice, and ameliorated fragmentation of wakefulness and cataplexy-like episodes in mouse models of narcolepsy. These findings indicate that TAK-994 is an orally available brain-penetrant OX2R-selective agonist with potential to improve narcolepsy-like symptoms.

Orexin 2 receptor-selective agonist danavorexton (TAK-925) promotes wakefulness in non-human primates and healthy individuals.

The orexin 2 receptor-selective agonist danavorexton (TAK-925) has been shown to produce wake-promoting effects in wild-type mice, narcolepsy-model mice, and individuals with narcolepsy type 1 and type 2. Here, we report wake-promoting effects of danavorexton in non-human primates and healthy men during their sleep phase. Electroencephalogram analyses revealed that subcutaneous administration of danavorexton significantly increased wakefulness in common marmosets (p < 0.05 at 0.1 mg kg-1 , and p < 0.001 at 1 mg kg-1 and 10 mg kg-1 ) and cynomolgus monkeys (p ≤ 0.05 at 1 mg kg-1 and 3 mg kg-1 ). In a phase 1b crossover, randomized, double-blind, placebo-controlled and active-controlled study in sleep-deprived healthy participants (ClinicalTrials.gov identifier: NCT03522506), modafinil 300 mg (used to demonstrate assay sensitivity) and continuous infusion of danavorexton 44 mg and danavorexton 112 mg showed statistically superior wake-promoting effects to placebo (n = 18). Measured using the Maintenance of Wakefulness Test, mean (standard deviation) sleep latencies during infusion of danavorexton 44 mg, danavorexton 112 mg and placebo were 21.4 (8.9), 31.8 (3.2) and 9.2 (6.4) min, respectively. Least-squares mean difference from placebo in average sleep latency was 16.8 min with danavorexton 44 mg and 30.2 min with danavorexton 112 mg (both p < 0.001). Karolinska Sleepiness Scale scores were statistically significantly lower (indicating decreased sleepiness) for participants receiving danavorexton than for those receiving placebo during infusion (danavorexton 44 mg, p = 0.010; danavorexton 112 mg, p < 0.001). Together, these results indicate that an orexin 2 receptor agonist increases wakefulness in non-human primates and healthy individuals during their sleep phase.

Diurnal Fluctuations of Orexin-A and -B in Cynomolgus Monkey Cerebrospinal Fluid Determined by a Novel Analytical Method Using Antiadsorptive Additive Treatment Followed by Nanoflow Liquid Chromatography-High-Resolution Mass Spectrometry.

Orexin-A (OXA) and -B (OXB) are involved in the regulation of multiple physiological functions including the sleep-wake states; therefore, it is critical to monitor their levels under various conditions. Unfortunately, the widely used radioimmunoassay has insufficient specificity for OXA. Although liquid chromatography-tandem mass spectrometry (LC-MS/MS) has higher specificity for OXA, previously reported OXA levels in human cerebrospinal fluid (CSF) measured using this technique are still inconsistent. Moreover, to the best of our knowledge, OXB has not been detected in the CSF. In this study, we established a novel method for OXA and OXB measurement. We noticed that OXA and OXB in the CSF was sticky; thus, citric acid and Tween 80 were used to prevent their nonspecific binding. Then, highly specific and sensitive nanoflow liquid chromatography-high-resolution mass spectrometry (nanoLC-HRMS) was used to measure OXA and OXB levels. Evaluation of the diurnal fluctuations of OXA and OXB in cisternal and lumbar CSF samples from cynomolgus monkeys revealed a sharp increase in the early light period, followed by a gradual increase to the maximum levels at the end of the light period, and then a sharp drop to the minimum levels during the early dark period. OXB levels were lower than OXA levels in cisternal CSF. Although basal OXA levels in individual monkeys showed substantial variations, the ratios between the maximum and minimum OXA levels of each monkey were similar. Our method for accurate OXA and OXB measurement should help improve our knowledge of orexin biology.

Role of the AMPA receptor in antidepressant effects of ketamine and potential of AMPA receptor potentiators as a novel antidepressant.

Ketamine exerts rapid and long-lasting antidepressant effects in patients with treatment-resistant depression. However, its clinical use is limited by its undesirable psychotomimetic side effects. Accumulating evidence from preclinical studies has shown that the antidepressant effects of ketamine are dependent on α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA-R) activation, which triggers activation of the mechanistic target of rapamycin pathway and brain-derived neurotrophic factor release. Thus, AMPA-R has emerged as a promising new target for novel antidepressants with a rapid onset of action. However, almost all known AMPA-R potentiators carry the risk of a narrow bell-shaped dose-response curve and a poor safety margin against seizures. Our data suggest that agonistic activity is not only related to the risks of bell-shaped dose-response curves and seizures but also to the reduced synaptic transmission and procognitive effects of AMPA-R potentiators. In this review, we describe our original screening approach that led to the discovery of an investigational AMPA-R potentiator with low agonistic activity, TAK-653. We further review the in vitro and in vivo profiles of TAK-653, including its procognitive and antidepressant-like effects, as well as its safety profile, in comparison with known AMPA-R potentiators with agonistic activity and AMPA, an AMPA-R agonist. The low agnostic activity of TAK-653 may overcome limitations of known AMPA-R potentiators. This article is part of the Special Issue on 'Ketamine and its Metabolites'.

Danavorexton, a selective orexin 2 receptor agonist, provides a symptomatic improvement in a narcolepsy mouse model.

Narcolepsy type 1 (NT1), caused by loss of orexin neurons, is a neurological disorder characterized by excessive daytime sleepiness, cataplexy, disrupted nighttime sleep, hypnagogic/hypnopompic hallucinations and sleep paralysis, as well as a high risk of obesity. Danavorexton (TAK-925) is a novel brain-penetrant orexin 2 receptor (OX2R)-selective agonist currently being evaluated in clinical trials for the treatment of hypersomnia disorders including NT1. Thus, detailed characterization of danavorexton is critical for validating therapeutic potential of OX2R-selective agonists. Here, we report preclinical characteristics of danavorexton as a therapeutic drug for NT1. Danavorexton showed rapid association/dissociation kinetics to OX2R. The activation mode of endogenous OX2R by danavorexton and orexin peptide was very similar in an electrophysiological analysis. In orexin/ataxin-3 mice, a mouse model of NT1, danavorexton promoted wakefulness, and ameliorated fragmentation of wakefulness during the active phase after both acute and repeated administration, suggesting a low risk of receptor desensitization. Electroencephalogram (EEG) power spectral analysis revealed that danavorexton, but not modafinil, normalized dysregulated EEG power spectrum in orexin/ataxin-3 mice during the active phase. Finally, repeated administration of danavorexton significantly suppressed the body weight gain in orexin/ataxin-3 mice. Danavorexton may have the potential to treat multiple symptoms of NT1. These preclinical findings, together with upcoming clinical observations of danavorexton, could improve our understanding of the pathophysiology of NT1 and therapeutic potential of OX2R agonists.

Orexin 2 receptor-selective agonist danavorexton improves narcolepsy phenotype in a mouse model and in human patients.

Narcolepsy type 1 (NT1) is a sleep disorder caused by a loss of orexinergic neurons. Narcolepsy type 2 (NT2) is heterogeneous; affected individuals typically have normal orexin levels. Following evaluation in mice, the effects of the orexin 2 receptor (OX2R)-selective agonist danavorexton were evaluated in single- and multiple-rising-dose studies in healthy adults, and in individuals with NT1 and NT2. In orexin/ataxin-3 narcolepsy mice, danavorexton reduced sleep/wakefulness fragmentation and cataplexy-like episodes during the active phase. In humans, danavorexton administered intravenously was well tolerated and was associated with marked improvements in sleep latency in both NT1 and NT2. In individuals with NT1, danavorexton dose-dependently increased sleep latency in the Maintenance of Wakefulness Test, up to the ceiling effect of 40 min, in both the single- and multiple-rising-dose studies. These findings indicate that OX2Rs remain functional despite long-term orexin loss in NT1. OX2R-selective agonists are a promising treatment for both NT1 and NT2.

Design, synthesis, and structure-activity relationship of TAK-418 and its derivatives as a novel series of LSD1 inhibitors with lowered risk of hematological side effects.

Lysine-specific demethylase 1 (LSD1) is an enzyme that demethylates methylated histone H3 lysine 4 (H3K4). Inhibition of LSD1 enzyme activity could increase H3K4 methylation levels and treat diseases associated with epigenetic dysregulation. However, known LSD1 inhibitors disrupt the interaction between LSD1 and cofactors such as GFI1B, causing the risk of hematological toxicity, including thrombocytopenia. Starting from a known LSD1 inhibitor (±)1 as a lead compound, a novel series of LSD1 inhibitors that do not induce the expression of GFI1 mRNA, an in vitro surrogate marker of LSD1-GFI1B dissociation, has been designed and synthesized. Initial structure-activity relationship (SAR) studies revealed the structural features key to avoiding GFI1 mRNA induction. Such SAR information enables optimization of LSD1 inhibitors with lowered risk of hematological side effects; TAK-418 ((1R,2R)-2n), the clinical candidate compound found through this optimization, has a hematological safety profile in rodents and humans. We further confirmed that oral administration of TAK-418 at 0.3 and 1 mg/kg for 2 weeks ameliorated memory deficits in mice with NMDA receptor hypofunction, suggesting potential of efficacy in neurodevelopmental disorders. TAK-418 warrants further investigation as a novel class of LSD1 inhibitors with a superior safety profile for the treatment of CNS disorders.

Orexin 2 receptor (OX2R) protein distribution measured by autoradiography using radiolabeled OX2R-selective antagonist EMPA in rodent brain and peripheral tissues.

Orexin, a neuropeptide, performs various physiological functions, including the regulation of emotion, feeding, metabolism, respiration, and sleep/wakefulness, by activating the orexin 1 receptor and orexin 2 receptor (OX2R). Owing to the pivotal role of OX2R in wakefulness and other biological functions, OX2R agonists are being developed. A detailed understanding of OX2R protein distribution is essential for determining the mechanisms of action of OX2R agonists; however, this has been hindered by the lack of selective antibodies. In this study, we first confirmed the OX2R-selective binding of [3H]-EMPA in in vitro autoradiography studies, using brain slices from OX2R knockout mice and their wild-type littermates. Subsequently, OX2R protein distribution in rats was comprehensively assessed in 51 brain regions and 10 peripheral tissues using in vitro autoradiography with [3H]-EMPA. The widespread distribution of OX2R protein, including that in previously unrecognized regions of the retrosplenial cortex, was identified. In contrast, OX2R protein expression was negligible/very low in peripheral tissues, suggesting that orexin exerts OX2R-dependent physiological functions primarily through activation of the central nervous system. These findings will be useful for understanding the wide range of biological functions of OX2R and the application of OX2R agonists in various disorders.

Investigating the Therapeutic Potential of LSD1 Enzyme Activity-Specific Inhibition by TAK-418 for Social and Memory Deficits in Rodent Disease Models.

Inhibition of lysine-specific demethylase 1 (LSD1) enzyme activity is a promising approach to treat diseases associated with epigenetic dysregulation, such as neurodevelopmental disorders. However, this concept has not been fully validated because genetic LSD1 deletion causes embryonic lethality and conventional LSD1 inhibitors cause thrombocytopenia via the dissociation of LSD1-cofactor complex. To characterize the therapeutic potential of LSD1 enzyme inhibition, we used TAK-418 and T-448, the LSD1 enzyme activity-specific inhibitors with minimal impact on the LSD1-cofactor complex. TAK-418 and T-448, by inhibiting brain LSD1 enzyme activity, consistently improved social deficits in animal models of neurodevelopmental disorders without causing thrombocytopenia. Moreover, TAK-418 improved memory deficits caused by aging or amyloid precursor protein overexpression. In contrast, TAK-418 did not improve memory deficits caused by miR-137 overexpression. Thus, miR-137 modulation may be involved in memory improvement by LSD1 inhibition. TAK-418 warrants further investigation as a novel therapeutic agent for diseases with epigenetic dysregulation.

TAK-653, an AMPA receptor potentiator with minimal agonistic activity, produces an antidepressant-like effect with a favorable safety profile in rats.

The N-methyl-d-aspartate receptor antagonist, ketamine, exhibits rapid and sustained antidepressant activity in patients with treatment-resistant depression (TRD), but its use is associated with psychotomimetic side effects. Evidence has suggested that the activation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors followed by activation of the mechanistic target of rapamycin (mTOR) signaling pathway and production of brain derived neurotrophic factor (BDNF) protein may underlie the antidepressant efficacy of ketamine. In this study, we characterized the antidepressant-like effects of TAK-653, a novel AMPA receptor potentiator with virtually no agonistic activity. In rat primary cortical neurons, TAK-653 significantly increased phosphorylated and activated forms of mTOR and p70S6 kinase and their upstream regulators Akt and extracellular signal-regulated kinase (ERK). TAK-653 also significantly increased BDNF protein levels in rat primary cortical neurons. Ketamine at 30 mg/kg, i.p. produced antidepressant-like effects in the reduction of submissive behavior model (RSBM) in rats. Ketamine's antidepressant-like effect was blocked by pretreatment with the AMPA receptor antagonist NBQX at 10 mg/kg, i.p., indicating the essential role of AMPA receptor activation in the antidepressant-like effect of ketamine. Consistent with this finding, a sub-chronic administration of TAK-653 for 6 days produced significant antidepressant-like effect in the rat RSBM. Unlike ketamine, however, TAK-653 did not induce a hyperlocomotor response in rats, which is a behavioral index associated with psychotomimetic side effects in humans. TAK-653 may be a promising drug for the treatment of major depressive disorders including TRD with the potential for an improved safety profile compared with ketamine.

Therapeutic potential of TAK-071, a muscarinic M1 receptor positive allosteric modulator with low cooperativity, for the treatment of cognitive deficits and negative symptoms associated with schizophrenia.

The selective activation of the muscarinic M1 receptor (M1R) may be a promising approach for treating cognitive impairment associated with cholinergic dysfunction. We previously reported that low cooperativity (α-value) is associated with a favorable cholinergic side effect profile of M1R positive allosteric modulators (M1 PAMs), as well as being a crucial factor for the cognitive improvement observed after combining M1 PAMs with donepezil, in rodents. In this study, we preclinically characterized TAK-071, a novel M1 PAM with low cooperativity (α-value = 199), as a new therapy for schizophrenia. We tested TAK-071 in the offspring of polyriboinosinic-polyribocytidylic acid-treated dams, which is a maternal immune activation model of schizophrenia. TAK-071 improved sociability deficits and working memory in this model. In a genetic mouse model of schizophrenia, miR-137 transgenic (Tg) mice, TAK-071 improved deficits in working memory, recognition memory, sociability, and sensorimotor gating. Patients with schizophrenia usually take several antipsychotics to treat positive symptoms. Thus, we also investigated the combined effects of TAK-071 with currently prescribed antipsychotics. Among the 10 antipsychotics tested, only olanzapine and quetiapine showed M1R antagonistic effects, which were counteracted by TAK-071 at possible effective concentrations for cognitive improvement in vitro. Moreover, haloperidol did not affect the ability of TAK-071 to improve working memory in miR-137 Tg mice, suggesting a low risk of losing efficacy when combined with dopamine D2 receptor antagonists. In conclusion, TAK-071 can exert beneficial effects on social behavior and cognitive function and could be a new therapy for schizophrenia.

Design, Synthesis, and Evaluation of [18F]T-914 as a Novel Positron-Emission Tomography Tracer for Lysine-Specific Demethylase 1.

Histone methylation is associated with the pathophysiology of neurodevelopmental disorders. Lysine-specific demethylase 1 (LSD1) catalyzes histone demethylation in a flavin adenine dinucleotide (FAD)-dependent manner. Thus, inhibiting LSD1 enzyme activity could offer a novel way to treat neurodevelopmental disorders. Assessing LSD1 target engagement using positron-emission tomography (PET) imaging could aid in developing therapeutic LSD1 inhibitors. In this study, PET probes based on 4-(2-aminocyclopropyl)benzamide derivatives that bind irreversibly to FAD found in LSD1 were examined. By optimizing the profiles of brain penetrance and brain-penetrant metabolites, T-914 (1g) was identified as a suitable PET tracer candidate. PET studies in nonhuman primates demonstrated that [18F]1g had heterogeneous brain uptake, which corresponded to known LSD1 expression levels. Moreover, brain uptake of [18F]1g was reduced by coadministration of unlabeled 1g, demonstrating blockable binding. These data suggest that [18F]1g warrants further investigation as a potential PET tracer candidate for assessing target engagement of LSD1.

Strictly regulated agonist-dependent activation of AMPA-R is the key characteristic of TAK-653 for robust synaptic responses and cognitive improvement.

Agonistic profiles of AMPA receptor (AMPA-R) potentiators may be associated with seizure risk and bell-shaped dose-response effects. Here, we report the pharmacological characteristics of a novel AMPA-R potentiator, TAK-653, which exhibits minimal agonistic properties. TAK-653 bound to the ligand binding domain of recombinant AMPA-R in a glutamate-dependent manner. TAK-653 strictly potentiated a glutamate-induced Ca2+ influx in hGluA1i-expressing CHO cells through structural interference at Ser743 in GluA1. In primary neurons, TAK-653 augmented AMPA-induced Ca2+ influx and AMPA-elicited currents via physiological AMPA-R with little agonistic effects. Interestingly, TAK-653 enhanced electrically evoked AMPA-R-mediated EPSPs more potently than AMPA (agonist) or LY451646 (AMPA-R potentiator with a prominent agonistic effect) in brain slices. Moreover, TAK-653 improved cognition for both working memory and recognition memory, while LY451646 did so only for recognition memory, and AMPA did not improve either. These data suggest that the facilitation of phasic AMPA-R activation by physiologically-released glutamate is the key to enhancing synaptic and cognitive functions, and nonselective activation of resting AMPA-Rs may negatively affect this process. Importantly, TAK-653 had a wide safety margin against convulsion; TAK-653 showed a 419-fold (plasma Cmax) and 1017-fold (AUC plasma) margin in rats. These findings provide insight into a therapeutically important aspect of AMPA-R potentiation.

Inhibition of KDM1A activity restores adult neurogenesis and improves hippocampal memory in a mouse model of Kabuki syndrome.

Kabuki syndrome (KS) is a rare cause of intellectual disability primarily caused by loss-of-function mutations in lysine-specific methyltransferase 2D (KMT2D), which normally adds methyl marks to lysine 4 on histone 3. Previous studies have shown that a mouse model of KS (Kmt2d +/ßGeo ) demonstrates disruption of adult neurogenesis and hippocampal memory. Proof-of-principle studies have shown postnatal rescue of neurological dysfunction following treatments that promote chromatin opening; however, these strategies are non-specific and do not directly address the primary defect of histone methylation. Since lysine-specific demethylase 1A (LSD1/KDM1A) normally removes the H3K4 methyl marks added by KMT2D, we hypothesized that inhibition of KDM1A demethylase activity may ameliorate molecular and phenotypic defects stemming from KMT2D loss. To test this hypothesis, we evaluated a recently developed KDM1A inhibitor (TAK-418) in Kmt2d +/ßGeo mice. We found that orally administered TAK-418 increases the numbers of newly born doublecortin (DCX)+ cells and processes in the hippocampus in a dose-dependent manner. We also observed TAK-418-dependent rescue of histone modification defects in hippocampus both by western blot and chromatin immunoprecipitation sequencing (ChIP-seq). Treatment rescues gene expression abnormalities including those of immediate early genes such as FBJ osteosarcoma oncogene (Fos) and FBJ osteosarcoma oncogene homolog B (Fosb). After 2 weeks of TAK-418, Kmt2d +/ßGeo mice demonstrated normalization of hippocampal memory defects. In summary, our data suggest that KDM1A inhibition is a plausible treatment strategy for KS and support the hypothesis that the epigenetic dysregulation secondary to KMT2D dysfunction plays a major role in the postnatal neurological disease phenotype in KS.