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Effective diagnosis of inflammation and cancer by molecular imaging is challenging because of interference from nonselective accumulation of the contrast agents in normal tissues. Here, we report a series of novel fluorescence imaging agents that efficiently target cyclooxygenase-2 (COX-2), which is normally absent from cells, but is found at high levels in inflammatory lesions and in many premalignant and malignant tumors. After either i.p. or i.v. injection, these reagents become highly enriched in inflamed or tumor tissue compared with normal tissue and this accumulation provides sufficient signal for in vivo fluorescence imaging. Further, we show that only the intact parent compound is found in the region of interest. COX-2–specific delivery was unambiguously confirmed using animals bearing targeted deletions of COX-2 and by blocking the COX-2 active site with high-affinity inhibitors in both in vitro and in vivo models. Because of their high specificity, contrast, and detectability, these fluorocoxibs are ideal candidates for detection of inflammatory lesions or early-stage COX-2–expressing human cancers, such as those in the esophagus, oropharynx, and colon. Cancer Res; 70(9); 3618–27. ©2010 AACR.

Supplementary Methods, Figures 1-6 from Selective Visualization of Cyclooxygenase-2 in Inflammation and Cancer by Targeted Fluorescent Imaging Agents

This Letter describes our ongoing effort to improve the clearance of selective M

The muscarinic acetylcholine receptor (mAChR) subtype 5 (M

We describe here a series of metabotropic glutamate receptor 7 (mGlu

Degeneration of basal forebrain cholinergic circuitry represents an early event in the development of Alzheimer's disease (AD). These alterations in central cholinergic function are associated with disruptions in arousal, sleep/wake architecture, and cognition. Changes in sleep/wake architecture are also present in normal aging and may represent a significant risk factor for AD. M1 muscarinic acetylcholine receptor (mAChR) positive allosteric modulators (PAMs) have been reported to enhance cognition across preclinical species and may also provide beneficial effects for age- and/or neurodegenerative disease-related changes in arousal and sleep. In the present study, electroencephalography was conducted in young animals (mice, rats and nonhuman primates [NHPs]) and in aged mice to examine the effects of the selective M1 PAM VU0453595 in comparison with the acetylcholinesterase inhibitor donepezil, M1/M4 agonist xanomeline (in NHPs), and M1 PAM BQCA (in rats) on sleep/wake architecture and arousal. In young wildtype mice, rats, and NHPs, but not in M1 mAChR KO mice, VU0453595 produced dose-related increases in high frequency gamma power, a correlate of arousal and cognition enhancement, without altering duration of time across all sleep/wake stages. Effects of VU0453595 in NHPs were observed within a dose range that did not induce cholinergic-mediated adverse effects. In contrast, donepezil and xanomeline increased time awake in rodents and engendered dose-limiting adverse effects in NHPs. Finally, VU0453595 attenuated age-related decreases in REM sleep duration in aged wildtype mice. Development of M1 PAMs represents a viable strategy for attenuating age-related and dementia-related pathological disturbances of sleep and arousal.

Herein, we report the discovery of the first selective and CNS penetrant mGlu7 PAM (VU6027459) derived from a "molecular switch" within a selective mGlu7 NAM chemotype. VU6027459 displayed CNS penetration in both mice (Kp = 2.74) and rats (Kp= 4.78), it was orally bioavailable in rats (%F = 69.5), and undesired activity at DAT was ablated.

[Image: see text] Herein, we report the discovery of a potent and selective dual DDR1/2 inhibitor, 7e (VU6015929), displaying low cytotoxicity, good kinome selectivity, and possessing an acceptable in vitro DMPK profile with good rodent in vivo pharmacokinetics. VU6015929 potently blocks collagen-induced DDR1 activation and collagen-IV production, suggesting DDR1 inhibition as an exciting target for antifibrotic therapy.

Background: This article describes the challenges in the discovery and optimization of mGlu2/4 heterodimer Positive Allosteric Modulators (PAMs). Methods: Initial forays based on VU0155041, a PAM of both the mGlu4 homodimer and the mGlu2/4 heterodimer, led to flat, intractable SAR that precluded advancement. Screening of a collection of 1,152 FDA approved drugs led to the discovery that febuxostat, an approved xanthine oxidase inhibitor, was a moderately potent PAM of the mGlu2/4 heterodimer (EC50 = 3.4 µM), but was peripherally restricted (rat Kp = 0.03). Optimization of this hit led to PAMs with improved potency (EC50s 2, an ~100-fold increase). Results: However, these new amide analogs of febuxostat proved to be either GIRK1/2 and GIRK1/4 activators (primary carboxamide congeners) or mGlu2 PAMs (secondary and tertiary amides) and not selective mGlu2/4 heterodimer PAMs. Conclusion: These results required the team to develop a new screening cascade paradigm, and exemplified the challenges in developing allosteric ligands for heterodimeric receptors.

This letter describes the further optimization of a series of mGlu3 NAMs based on an N-aryl phenoxyethoxy pyridinone core. A multidimensional optimization campaign, with focused matrix libraries, quickly established challenging SAR, enantiospecific activity, differences in assay read-outs (Ca2+ flux via a promiscuous G protein (Gα15) versus native coupling to GIRK channels), identified both full and partial mGlu3 NAMs and a new in vivo tool compound, VU6017587. This mGlu3 NAM showed efficacy in tail suspension, elevated zero maze and marble burying, suggesting selective inhibition of mGlu3 affords anxiolytic-like and antidepressant-like phenotypes in mice.

This letter describes a diversity-oriented library approach to rapidly assess diverse heterocycles as bioisosteric replacements for a metabolically labile amide moiety within a series of mGlu7 negative allosteric modulators (NAMs). SAR rapidly honed in on either a 1,2,4- or 1,3,4-oxadizaole ring system as an effective bioisostere for the amide. Further optimization of the southern region of the mGlu7 NAM chemotype led to the discovery of VU6019278, a potent mGlu7 NAM (IC50 = 501 nM, 6.3% L-AP4 Min) with favorable plasma protein binding (rat fu = 0.10), low predicted hepatic clearance (rat CLhep = 27.7 mL/min/kg) and high CNS penetration (rat Kp = 4.9, Kp,uu = 0.65).

This letter describes the first account of the chemical optimization (SAR and DMPK profiling) of a new series of mGlu4 positive allosteric modulators (PAMs), leading to the identification of VU0652957 (VU2957, Valiglurax), a compound profiled as a preclinical development candidate. Here, we detail the challenges faced in allosteric modulator programs (e.g., steep SAR, as well as subtle structural changes affecting overall physiochemical/DMPK properties and CNS penetration).

This letter describes the further chemical optimization of VU0424238 (auglurant), an mGlu5 NAM clinical candidate that failed in non-human primate (NHP) 28 day toxicology due to accumulation of a species-specific aldehyde oxidase (AO) metabolite of the pyrimidine head group. Here, we excised the pyrimidine moiety, identified the minimum pharmacophore, and then developed a new series of saturated ether head groups that ablated any AO contribution to metabolism. Putative back-up compounds in this novel series provided increased sp3 character, uniform CYP450-mediated metabolism across species, good functional potency and high CNS penetration. Key to the optimization was a combination of matrix and iterative libraries that allowed rapid surveillance of multiple domains of the allosteric ligand.

This letter describes the on-going SAR efforts to develop PLD1, PLD2 and dual PLD1/2 inhibitors with improved physiochemical and disposition properties as well as securing intellectual property position. Previous PLD inhibitors, based on a triazaspiro[4.5]decanone core proved to be highly selective PLD2 inhibitors, but with low plasma free fraction (rat, human fu 65 mL/min/kg) and very short half-lives in vivo (t1/2 3 h), and led to the first issued US patent claiming composition of matter for small molecule PLD inhibitors.

Sterol 14α-demethylases (CYP51) are cytochrome P450 enzymes essential for sterol biosynthesis in eukaryotes and therapeutic targets for antifungal azoles. Multiple attempts to repurpose antifungals for treatment of human infections with protozoa (Trypanosomatidae) have been undertaken, yet so far none of them have revealed sufficient efficacy. VNI and its derivative VFV are two potent experimental inhibitors of Trypanosomatidae CYP51, effective in vivo against Chagas disease, visceral leishmaniasis, and sleeping sickness and currently under consideration as antiprotozoal drug candidates. However, VNI is less potent against Leishmania and drug-resistant strains of Trypanosoma cruzi and VFV, while displaying a broader spectrum of antiprotozoal activity, and is metabolically less stable. In this work we have designed, synthesized, and characterized a set of close analogues and identified two new compounds (7 and 9) that exceed VNI/VFV in their spectra of antiprotozoal activity, microsomal stability, and pharmacokinetics (tissue distribution in particular) and, like VNI/VFV, reveal no acute toxicity.

A scaffold hopping exercise from a monocyclic mGlu2 NAM with poor rodent PK led to two novel heterobicyclic series of mGlu2 NAMs based on either a functionalized pyrazolo[1,5- a]pyrimidine-5-carboxamide core or a thieno[3,2- b]pyridine-5-carboxamide core. These novel analogues possess enhanced rodent PK, while also maintaining good mGlu2 NAM potency, selectivity (versus mGlu3 and the remaining six mGlu receptors), and high CNS penetration. Interestingly, SAR was divergent between the new 5,6-heterobicyclic systems.

[Image: see text] Herein, we report the discovery of a novel potent, selective, CNS penetrant, and orally bioavailable mGlu(4) PAM, VU0652957 (VU2957, Valiglurax). VU2957 possessed attractive in vitro and in vivo pharmacological and DMPK properties across species. To advance toward the clinic, a spray-dried dispersion (SDD) formulation of VU2957 was developed to support IND-enabling toxicology studies. Based on its overall profile, VU2957 was evaluated as a preclinical development candidate for the treatment of Parkinson’s disease.

A high throughput screen (HTS) identified a novel, but weak (EC

The activin-like kinases are a family of kinases that play important roles in a variety of disease states. Of this class of kinases, ALK2, has been shown by a gain-of-function to be the primary driver of the childhood skeletal disease fibrodysplasia ossificans progressiva (FOP) and more recently the pediatric cancer diffuse intrinsic pontine glioma (DIPG). Herein, we report our efforts to identify a novel imidazo[1,2-a]pyridine scaffold as potent inhibitors of ALK2 with good in vivo pharmacokinetic properties suitable for future animal studies.

A High-Throughput Screening (HTS) campaign identified a fundamentally new mGlu(7) NAM chemotype, based on an ethyl-8-methoxy-4-(4-phenylpiperazin-1-yl)quinolone carboxylate core. The initial hit, VU0226390, was a potent mGlu(7) NAM (IC(50) = 647 nM, 6% L-AP4 min) with selectivity versus the other group III mGlu receptors (>30 μM vs. mGlu(4) and mGlu(8)). A multi-dimensional optimization effort surveyed all regions of this new chemotype, and found very steep SAR, reminiscent of allosteric modulators, and unexpected piperazine mimetics (whereas classical bioisosteres failed). While mGlu(7) NAM potency could be improved (IC(50)s ~ 350 nM), the necessity of the ethyl ester moiety and poor physiochemical and DMPK properties precluded optimization towards in vivo tool compounds or clinical candidates. Still, this hit-to-lead campaign afforded key medicinal chemistry insights and new opportunities.

Degeneration of basal forebrain cholinergic circuitry represents an early event in the development of Alzheimer’s disease (AD). These alterations in central cholinergic function are associated with disruptions in arousal, sleep/wake architecture, and cognition. Changes in sleep/wake architecture are also present in normal aging and may represent a significant risk factor for AD. M(1) muscarinic acetylcholine receptor (mAChR) positive allosteric modulators (PAMs) have been reported to enhance cognition across preclinical species and may also provide beneficial effects for age- and/or neurodegenerative disease-related changes in arousal and sleep. In the present study, electroencephalography was conducted in young animals (mice, rats and nonhuman primates [NHPs]) and in aged mice to examine the effects of the selective M(1) PAM VU0453595 in comparison with the acetylcholinesterase inhibitor donepezil, M(1)/M(4) agonist xanomeline (in NHPs), and M(1) PAM BQCA (in rats) on sleep/wake architecture and arousal. In young wildtype mice, rats, and NHPs, but not in M(1) mAChR KO mice, VU0453595 produced dose-related increases in high frequency gamma power, a correlate of arousal and cognition enhancement, without altering duration of time across all sleep/wake stages. Effects of VU0453595 in NHPs were observed within a dose range that did not induce cholinergic-mediated adverse effects. In contrast, donepezil and xanomeline increased time awake in rodents and engendered dose-limiting adverse effects in NHPs. Finally, VU0453595 attenuated age-related decreases in REM sleep duration in aged wildtype mice. Development of M(1) PAMs represents a viable strategy for attenuating age-related and dementia-related pathological disturbances of sleep and arousal.

This work describes the discovery and characterization of novel 6-(1H-pyrazolo[4,3-b]pyridin-3-yl)amino-benzo[d]isothiazole-3-carboxamides as mGlu4 PAMs. This scaffold provides improved metabolic clearance and CYP1A2 profiles compared to previously discovered mGlu4 PAMs. From this work, 27o (VU6001376) was identified as a potent (EC50 = 50.1 nM, 50.5% GluMax) and selective mGlu4 PAM with an excellent rat DMPK profile (in vivo rat CLp = 3.1 mL/min/kg, t1/2 = 445 min, CYP1A2 IC50 > 30 μM). Compound 27o was also active in reversing haloperidol induced catalepsy in a rodent preclinical model of Parkinson’s disease.

[Image: see text] Herein, we report the chemical optimization of a new series of M(1) positive allosteric modulators (PAMs) based on a novel pyrrolo[2,3-b]pyridine core, developed via scaffold hopping and iterative parallel synthesis. The vast majority of analogs in this series proved to display robust cholinergic seizure activity. However, by removal of the secondary hydroxyl group, VU6007477 resulted with good rat M(1) PAM potency (EC(50) = 230 nM, 93% ACh max), minimal M(1) agonist activity (agonist EC(50) > 10 μM), good CNS penetration (rat brain/plasma K(p) = 0.28, K(p,uu) = 0.32; mouse K(p) = 0.16, K(p,uu) = 0.18), and no cholinergic adverse events (AEs, e.g., seizures). This work demonstrates that within a chemical series prone to robust M(1) ago-PAM activity, SAR can result, which affords pure M(1) PAMs, devoid of cholinergic toxicity/seizure liability.

Recent clinical and preclinical studies suggest that selective activators of the M(4) muscarinic acetylcholine receptor have potential as a novel treatment for schizophrenia. M(4) activation inhibits striatal dopamine release by mobilizing endocannabinoids, providing a mechanism for local effects on dopamine signaling in the striatum but not in extrastriatal areas. G protein-coupled receptors (GPCRs) typically induce endocannabinoid release through activation of Gα(q/11)-type G proteins whereas M(4) transduction occurs through Gα(i/o)-type G proteins. We now report that the ability of M(4) to inhibit dopamine release and induce antipsychotic-like effects in animal models is dependent on co-activation of the Gα(q/11)-coupled mGlu(1) subtype of metabotropic glutamate (mGlu) receptor. This is especially interesting in light of recent findings that multiple loss of function single nucleotide polymorphisms (SNPs) in the human gene encoding mGlu(1) (GRM1) are associated with schizophrenia, and points to GRM1/mGlu(1) as a gene within the “druggable genome” that could be targeted for the treatment of schizophrenia. Herein, we report that potentiation of mGlu(1) signaling following thalamo-striatal stimulation is sufficient to inhibit striatal dopamine release, and that a novel mGlu(1) positive allosteric modulator (PAM) exerts robust antipsychotic-like effects through an endocannabinoid-dependent mechanism. However, unlike M(4), mGlu(1) does not directly inhibit dopamine D(1) receptor signaling and does not reduce motivational responding. Taken together, these findings highlight a novel mechanism of cross talk between mGlu(1) and M(4) and demonstrate that highly selective mGlu(1) PAMs may provide a novel strategy for the treatment of positive symptoms associated with schizophrenia.

Previous reports from our laboratory disclosed the structure and activity of a novel 1H-pyrazolo[4,3-b]pyridine-3-amine scaffold (VU8506) which showed excellent potency, selectivity and in vivo efficacy in preclinical rodent models of Parkinson’s disease. Unfortunately, this compound suffered from significant CYP1A2 induction as measured through upstream AhR activation (125-fold) and thus was precluded from further advancement in chronic studies. Herein, we report a new scaffold developed recently which was systematically studied in order to mitigate the CYP1A2 liabilities presented in the earlier scaffolds. We have identified a novel structure that maintains the potency and selectivity of other mGlu4 PAMs, leading to 9i (hmGlu4 EC50 = 43 nM; AhR activation = 2.3-fold).

This letter describes the chemical optimization of a new series of M1 positive allosteric modulators (PAMs) based on a novel benzomorpholine core, developed via iterative parallel synthesis, and culminating in the highly utilized rodent in vivo tool compound, VU0486846 (7), devoid of adverse effect liability. This is the first report of the optimization campaign (SAR and DMPK profiling) that led to the discovery of VU0486846 and details all of the challenges faced in allosteric modulator programs (both steep and flat SAR, as well as subtle structural changes affecting CNS penetration and overall physiochemical and DMPK properties).

The inward rectifier potassium (Kir) channel Kir4.1 (KCNJ10) carries out important physiologic roles in epithelial cells of the kidney, astrocytes in the central nervous system, and stria vascularis of the inner ear. Loss-of-function mutations in KCNJ10 lead to EAST/SeSAME syndrome, which is characterized by epilepsy, ataxia, renal salt wasting, and sensorineural deafness. Although genetic approaches have been indispensable for establishing the importance of Kir4.1 in the normal function of these tissues, the availability of pharmacological tools for acutely manipulating the activity of Kir4.1 in genetically normal animals has been lacking. We therefore carried out a high-throughput screen of 76,575 compounds from the Vanderbilt Institute of Chemical Biology library for small-molecule modulators of Kir4.1. The most potent inhibitor identified was 2-(2-bromo-4-isopropylphenoxy)-N-(2,2,6,6-tetramethylpiperidin-4-yl)acetamide (VU0134992). In whole-cell patch-clamp electrophysiology experiments, VU0134992 inhibits Kir4.1 with an IC(50) value of 0.97 µM and is 9-fold selective for homomeric Kir4.1 over Kir4.1/5.1 concatemeric channels (IC(50) = 9 µM) at −120 mV. In thallium (Tl(+)) flux assays, VU0134992 is greater than 30-fold selective for Kir4.1 over Kir1.1, Kir2.1, and Kir2.2; is weakly active toward Kir2.3, Kir6.2/SUR1, and Kir7.1; and is equally active toward Kir3.1/3.2, Kir3.1/3.4, and Kir4.2. This potency and selectivity profile is superior to Kir4.1 inhibitors amitriptyline, nortriptyline, and fluoxetine. Medicinal chemistry identified components of VU0134992 that are critical for inhibiting Kir4.1. Patch-clamp electrophysiology, molecular modeling, and site-directed mutagenesis identified pore-lining glutamate 158 and isoleucine 159 as critical residues for block of the channel. VU0134992 displayed a large free unbound fraction (f(u)) in rat plasma (f(u) = 0.213). Consistent with the known role of Kir4.1 in renal function, oral dosing of VU0134992 led to a dose-dependent diuresis, natriuresis, and kaliuresis in rats. Thus, VU0134992 represents the first in vivo active tool compound for probing the therapeutic potential of Kir4.1 as a novel diuretic target for the treatment of hypertension.

Based on previous work that established fused heterocycles as viable alternatives for the picolinamide core of our lead series of mGlu(5) negative allosteric modulators (NAMs), we designed a novel series of 6-(pyrimidin-5-ylmethyl)quinoline-8-carboxamide mGlu(5) NAMs. These new quinoline derivatives also contained carbon linkers as replacements for the diaryl ether oxygen atom common to our previously published chemotypes. Compounds were evaluated in a cell-based functional mGlu(5) assay, and an exemplar analog 27 was more than 60-fold selective versus the other seven mGlu receptors. Selected compounds were also studied in metabolic stability assays in rat and human S9 hepatic fractions and exhibited a mixture of P450- and non-P450-mediated metabolism.

Selective activation of the M(1) subtype of muscarinic acetylcholine receptor, via positive allosteric modulation (PAM), is an exciting strategy to improve cognition in schizophrenia and Alzheimer’s disease patients. However, highly potent M(1) ago-PAMs, such as MK-7622, PF-06764427, and PF-06827443, can engender excessive activation of M(1), leading to agonist actions in the prefrontal cortex (PFC) that impair cognitive function, induce behavioral convulsions, and result in other classic cholinergic adverse events (AEs). Here, we report a fundamentally new and highly selective M(1) PAM, VU0486846. VU0486846 possesses only weak agonist activity in M(1)-expressing cell lines with high receptor reserve and is devoid of agonist actions in the PFC, unlike previously reported ago-PAMs MK-7622, PF-06764427, and PF-06827443. Moreover, VU0486846 shows no interaction with antagonist binding at the orthosteric acetylcholine (ACh) site (e.g., neither bitopic nor displaying negative cooperativity with [(3)H]-NMS binding at the orthosteric site), no seizure liability at high brain exposures, and no cholinergic AEs. However, as opposed to ago-PAMs, VU0486846 produces robust efficacy in the novel object recognition model of cognitive function. Importantly, we show for the first time that an M(1) PAM can reverse the cognitive deficits induced by atypical antipsychotics, such as risperidone. These findings further strengthen the argument that compounds with modest in vitro M(1) PAM activity (EC(50) > 100 nM) and pure-PAM activity in native tissues display robust procognitive efficacy without AEs mediated by excessive activation of M(1). Overall, the combination of compound assessment with recombinant in vitro assays (mindful of receptor reserve), native tissue systems (PFC), and phenotypic screens (behavioral convulsions) is essential to fully understand and evaluate lead compounds and enhance success in clinical development.

This Letter describes the synthesis and optimization of a series of heteroaryl-pyrrolidinone positive allosteric modulators (PAMs) of the muscarinic acetylcholine receptor M1 (mAChR M1). Through the continued optimization of M1 PAM tool compound VU0453595, with a focus on replacement of the 6,7-dihydro-5H-pyrrolo[3,4-b]pyridin-5-one with a wide variety of alternative 4,5-dihydropyrrolo-fused heteroaromatics, the generation of M1 PAMs with structurally novel chemotypes is disclosed. Two compounds from these subseries, 8b (VU6005610) and 20a (VU6005852), show robust selectivity for the M1 mAChR, and no M1 agonism. Both compounds have favorable preliminary PK profiles in vitro;8b additionally demonstrates high brain exposure in a rodent IV cassette model.

A high throughput screen (HTS) identified a novel, but weak (EC50 = 6.2 μM, 97% Glu Max) mGlu4 PAM chemotype based on a 1,4-thiazepane core, VU0544412. Reaction development and chemical optimization delivered a potent mGlu4 PAM VU6022296 (EC50 = 32.8 nM, 108% Glu Max) with good CNS penetration (Kp = 0.45, Kp,uu = 0.70) and enantiopreference. Finally, VU6022296 displayed robust, dose-dependent efficacy in reversing Haloperidol-Induced Catalepsy (HIC), a rodent preclinical Parkinson’s disease model.

Aldehyde oxidase (AO) and xanthine oxidase (XO) are molybdo-flavoenzymes that catalyze oxidation of aromatic azaheterocycles. Differences in AO activity have been reported among various species, including rats, humans, and monkeys. Herein we report a species difference in the enzymes responsible for the metabolism of the negative allosteric modulator of metabotropic glutamate receptor subtype 5 (mGlu5 NAM) VU0424238 (VU238, auglurant). Hepatic S9 incubations with AO and XO specific inhibitors hydralazine and allopurinol indicated that rats and cynomolgus monkeys both oxidized VU238 to the 6-oxopyrimidine metabolite M1 via an AO-mediated pathway, whereas secondary oxidation to the 2,6-dioxopyrimidine metabolite M2 was mediated predominantly by AO in monkeys and XO in rats. Despite differences in enzymatic pathways, intrinsic clearance (CLint) of M1 was similar between species (cynomolgus and rat CLint = 2.00 ± 0.040 and 2.19 ± 0.201 μl/min per milligram of protein, respectively). Inhibitor studies in the S9 of multiple species indicated that oxidation of VU238 to M1 was mediated predominantly by AO in humans, cynomolgus and rhesus monkeys, rats, mice, guinea pigs, and minipigs. Oxidation of M1 to M2 was mediated predominantly by XO in rats and mice and by AO in monkeys and guinea pigs, whereas low turnover prevented enzyme phenotyping in humans and minipigs. Additionally, inhibitor experiments indicated that oxidation at the 2-position of the pyrimidine ring of the known AO substrate, BIBX1382, was mediated by AO in all species, although production of this metabolite was comparatively low in rats and mice. These data may suggest low reactivity of rat AO toward 2-oxidation of pyrimidine-containing compounds and highlight the importance of thoroughly characterizing AO-metabolized drug candidates in multiple preclinical species.

Herein, we report the structure–activity relationships within a series of mGlu7 PAMs based on a pyrazolo[1,5-a]pyrimidine core with excellent CNS penetration (Kps > 1 and Kp,uus > 1). Analogues in this series proved to display a range of Group III mGlu receptor selectivity, but VU6005649 emerged as the first dual mGlu7/8 PAM, filling a void in the Group III mGlu receptor PAM toolbox and demonstrating in vivo efficacy in a mouse contextual fear conditioning model.

This communication details the kilogram-scale synthesis of N-(5-fluoropyridin-2-yl)-6-methyl-4-(pyrimidin-5-yloxy)picolinamide (VU0424238, auglurant), a novel mGlu5 negative allosteric modulator (NAM) developed as an alternative treatment for depression. The process highlights a challenging pyridine N-oxidation sequence, an SNAr reaction, and the elimination of all chromatography steps (required in the medicinal chemistry route) with replacement by highly efficient recrystallizations (save one silica plug). The improved process was utilized for the preparation of a 1.2 kg toxicology batch, as well as a 2.82 kg GMP batch to support the Phase I trial, in very high purity (99.8%).

Herein, we detail the optimization of the mGlu2 negative allosteric modulator (NAM), VU6001192, by a reductionist approach to afford a novel, simplified mGlu2 NAM scaffold. This new chemotype not only affords potent and selective mGlu2 inhibition, as exemplified by VU6001966 (mGlu2 IC50 = 78 nM, mGlu3 IC50 > 30 μM), but also excellent central nervous system (CNS) penetration (Kp = 1.9, Kp,uu = 0.78), a feature devoid in all previously disclosed mGlu2 NAMs (Kps ≈ 0.3, Kp,uus ≈ 0.1). Moreover, this series, based on overall properties, represents an exciting lead series for potential mGlu2 PET tracer development.

A duplexed, functional multiaddition high throughput screen and subsequent optimization effort identified the first orally bioavailable and CNS penetrant glucagon-like peptide-1 receptor (GLP-1R) noncompetitive antagonist. Antagonist 5d not only blocked exendin-4-stimulated insulin release in islets but also lowered insulin levels while increasing blood glucose in vivo.

Herein, we report the structure–activity relationships within a series of potent, selective, and orally bioavailable muscarinic acetylcholine receptor 4 (M4) positive allosteric modulators (PAMs). Compound 6c (VU0467485) possesses robust in vitro M4 PAM potency across species and in vivo efficacy in preclinical models of schizophrenia. Coupled with an attractive DMPK profile and suitable predicted human PK, 6c (VU0467485) was evaluated as a preclinical development candidate.

Herein, we report the synthesis and structure-activity relationship of a novel series of (R)-4,4-difluoropiperidine core scaffold as dopamine receptor 4 (D4) antagonists. A series of compounds from this scaffold are highly potent against the D4 receptor and selective against the other dopamine receptors. In addition, we were able to confirm the active isomer as the (R)-enantiomer via an X-ray crystal structure.

This letter describes the further deconstruction of the known PAR4 inhibitor chemotypes (MWs 490 – 525 and with high plasma protein binding) to identify a minimum PAR4 pharmacophore devoid of metabolic liabilities and improved properties. This exercise identified a greatly simplified 2-methoxy-6-arylimidazo[2,1-b][1,3,4]thiadiazole scaffold that afforded nanomolar inhibition of both activating peptide and γ-thrombin mediated PAR4 stimulation, while reducing both molecular weight and the number of hydrogen bond donors/acceptors by ~50%. This minimum PAR4 pharmacophore, with competitive inhibition, versus non-competitive of the larger chemotypes, allows an ideal starting point to incorporate desired functional groups to engender optimal DMPK properties towards a preclinical candidate.

Glucose-stimulated insulin secretion from pancreatic β-cells is controlled by ATP-regulated potassium (K(ATP)) channels composed of Kir6.2 and sulfonylurea receptor 1 (SUR1) subunits. The K(ATP) channel-opener diazoxide is FDA-approved for treating hyperinsulinism and hypoglycemia but suffers from off-target effects on vascular K(ATP) channels and other ion channels. The development of more specific openers would provide critically needed tool compounds for probing the therapeutic potential of Kir6.2/SUR1 activation. Here, we characterize a novel scaffold activator of Kir6.2/SUR1 that our group recently discovered in a high-throughput screen. Optimization efforts with medicinal chemistry identified key structural elements that are essential for VU0071063-dependent opening of Kir6.2/SUR1. VU0071063 has no effects on heterologously expressed Kir6.1/SUR2B channels or ductus arteriole tone, indicating it does not open vascular K(ATP) channels. VU0071063 induces hyperpolarization of β-cell membrane potential and inhibits insulin secretion more potently than diazoxide. VU0071063 exhibits metabolic and pharmacokinetic properties that are favorable for an in vivo probe and is brain penetrant. Administration of VU0071063 inhibits glucose-stimulated insulin secretion and glucose-lowering in mice. Taken together, these studies indicate that VU0071063 is a more potent and specific opener of Kir6.2/SUR1 than diazoxide and should be useful as an in vitro and in vivo tool compound for investigating the therapeutic potential of Kir6.2/SUR1 expressed in the pancreas and brain.

This letter describes the further optimization of a series of mGlu

This letter describes a diversity-oriented library approach to rapidly assess diverse heterocycles as bioisosteric replacements for a metabolically labile amide moiety within a series of mGlu

A High-Throughput Screening (HTS) campaign identified a fundamentally new mGlu7 NAM chemotype, based on an ethyl-8-methoxy-4-(4-phenylpiperazin-1-yl)quinolone carboxylate core. The initial hit, VU0226390, was a potent mGlu7 NAM (IC50 = 647 nM, 6% L-AP4 min) with selectivity versus the other group III mGlu receptors (>30 μM vs. mGlu4 and mGlu8). A multi-dimensional optimization effort surveyed all regions of this new chemotype, and found very steep SAR, reminiscent of allosteric modulators, and unexpected piperazine mimetics (whereas classical bioisosteres failed). While mGlu7 NAM potency could be improved (IC50s ~ 350 nM), the necessity of the ethyl ester moiety and poor physiochemical and DMPK properties precluded optimization towards in vivo tool compounds or clinical candidates. Still, this hit-to-lead campaign afforded key medicinal chemistry insights and new opportunities.

Here, we describe the development of a series of highly selective PAR4 antagonists with nanomolar potency and selectivity versus PAR1, derived from the indole-based 3. Of these, 9j (PAR4 IC50 = 445 nM, PAR1 response IC50 > 30 µM) and 10h (PAR4 IC50 = 179 nM, PAR1 response IC50 > 30 µM) maintained an overall favorable in vitro DMPK profile, encouraging rat/mouse in vivo pharmacokinetics (PK) and activity against γ-thrombin.

This letter describes the further chemical optimization of the picolinamide-derived family of mGlu4 PAMs wherein we identified a 3-amino substituent to the picolinamide warhead that engendered potency, CNS penetration and in vivo efficacy. From this optimization campaign, VU0477886 emerged as a potent (EC50 = 95 nM, 89% Glu Max) mGlu4 PAM with an attractive DMPK profile (brain:plasma Kp = 1.3), rat CLp = 4.0 mL/min/kg, t1/2 = 3.7 h) and robust efficacy in our standard preclinical Parkinson's disease model, haloperidol-induced catalepsy (HIC).

Herein, we report the synthesis and structure–activity relationship of a series of chiral alkoxymethyl morpholine analogs. Our efforts have culminated in the identification of (S)-2-(((6-chloropyridin-2-yl) oxy)methyl)-4-((6-fluoro-1H-indol-3-yl)methyl)morpholine as a novel potent and selective dopamine D4 receptor antagonist with selectivity against the other dopamine receptors tested (