The imidazo[1,2-a]pyridine ring system as a scaffold for potent dual phosphoinositide-3-kinase (PI3K)/mammalian target of rapamycin (mTOR) inhibitors.

Based on lead compound 1, which was discovered from a high-throughput screen, a series of PI3Kα/mTOR inhibitors were evaluated that contained an imidazo[1,2-a]pyridine as a core replacement for the benzimidazole contained in 1. By exploring various ring systems that occupy the affinity pocket, two fragments containing a methoxypyridine were identified that gave <100 nM potency toward PI3Kα in enzyme and cellular assays with moderate stability in rat and human liver microsomes. With the two methoxypyridine groups selected to occupy the affinity pocket, analogs were prepared with various fragments intended to occupy the ribose pocket of PI3Kα and mTOR. From these analogs, tertiary alcohol 18 was chosen for in vivo pharmacodynamic evaluation based on its potency in the PI3Kα cellular assay, microsomal stability, and in vivo pharmacokinetic properties. In a mouse liver pharmacodynamic assay, compound 18 showed 56% inhibition of HFG-induced AKT (Ser473) phosphorylation at a 30 mg/kg dose.

Small Molecule Disruptors of the Glucokinase-Glucokinase Regulatory Protein Interaction: 5. A Novel Aryl Sulfone Series, Optimization Through Conformational Analysis.

The glucokinase-glucokinase regulatory protein (GK-GKRP) complex plays an important role in controlling glucose homeostasis in the liver. We have recently disclosed a series of arylpiperazines as in vitro and in vivo disruptors of the GK-GKRP complex with efficacy in rodent models of type 2 diabetes mellitus (T2DM). Herein, we describe a new class of aryl sulfones as disruptors of the GK-GKRP complex, where the central piperazine scaffold has been replaced by an aromatic group. Conformational analysis and exploration of the structure-activity relationships of this new class of compounds led to the identification of potent GK-GKRP disruptors. Further optimization of this novel series delivered thiazole sulfone 93, which was able to disrupt the GK-GKRP interaction in vitro and in vivo and, by doing so, increases cytoplasmic levels of unbound GK.

Optimization of potency and pharmacokinetic properties of tetrahydroisoquinoline transient receptor potential melastatin 8 (TRPM8) antagonists.

Transient receptor potential melastatin 8 (TRPM8) is a nonselective cation channel expressed in a subpopulation of sensory neurons in the peripheral nervous system. TRPM8 is the predominant mammalian cold temperature thermosensor and is activated by cold temperatures ranging from 8 to 25 °C and cooling compounds such as menthol or icilin. TRPM8 antagonists are being pursued as potential therapeutics for treatment of pain and bladder disorders. This manuscript outlines new developments in the SAR of a lead series of 1,2,3,4-tetrahydroisoquinoline derivatives with emphasis on strategies to improve pharmacokinetic properties and potency. Selected compounds were profiled in two TRPM8 target-specific in vivo coverage models in rats (the icilin-induced wet dog shake model and the cold pressor test). Compound 45 demonstrated robust efficacy in both pharmacodynamic models with ED90 values <3 mg/kg.

Discovery of N-(3,5-bis(1-pyrrolidylmethyl)-4-hydroxybenzyl)-4-methoxybenzenesulfamide (sulcardine) as a novel anti-arrhythmic agent.

AIM: To investigate the anti-arrhythmic effects of sulfamide analogues of changrolin and to characterize the sulfate of compound 6f (sulcardine sulfate, Sul) as a novel anti-arrhythmic agent. METHODS: The anti-arrhythmic effects of compounds were studied against aconitine-induced arrhythmias in rats and ouabain-induced arrhythmias in guinea pigs. The effects of Sul on transmembrane action potentials were investigated in isolated rabbit sinoatrial nodes and guinea-pig papillary muscles using intracellular recording. With a whole-cell recording technique, the effects of Sul on sodium current, calcium current, and potassium currents were examined in isolated single guinea-pig ventricular myocytes. RESULTS: In aconitine-induced arrhythmias of rats, sulfamide analogues of changrolin (4, 5, and 6a-6p) exhibited various anti-arrhythmic activities. The sulfate of compound 6f (Sul) increased the amount of aconitine required to induce arrhythmias in each treated animal. The ED50 value of Sul in rats was 196 mg/kg. In ouabain-induced arrhythmias of guinea pigs, 25, 50, and 100 mg/kg doses of Sul increased the dose of ouabain required to induce VP, VT, and VF in a dose-dependent manner. In papillary preparations, Sul produced a concentration-dependent decrease in APA and V(max), prolonged APD(90) and ERP, whereas RP was unaffected. In the spontaneously beating sinus nodes, Sul reduced APA and V(max) in a concentration-dependent manner. The whole-cell recording studies revealed that Sul produced a reversible reduction in I(Na) (IC50=26.9 µmol/L) and I(Ca,L)(IC50=69.2 µmol/L), whereas the inward rectifier (I(K1)) and the delayed rectifier potassium currents (I(K)) were unaffected. CONCLUSION: As a multi-ion channel blocker, Sul may have potent efficacy in anti-atrial and ventricular arrhythmias.

Selective class I phosphoinositide 3-kinase inhibitors: optimization of a series of pyridyltriazines leading to the identification of a clinical candidate, AMG 511.

The phosphoinositide 3-kinase family catalyzes the phosphorylation of phosphatidylinositol-4,5-diphosphate to phosphatidylinositol-3,4,5-triphosphate, a secondary messenger which plays a critical role in important cellular functions such as metabolism, cell growth, and cell survival. Our efforts to identify potent, efficacious, and orally available phosphatidylinositol 3-kinase (PI3K) inhibitors as potential cancer therapeutics have resulted in the discovery of 4-(2-((6-methoxypyridin-3-yl)amino)-5-((4-(methylsulfonyl)piperazin-1-yl)methyl)pyridin-3-yl)-6-methyl-1,3,5-triazin-2-amine (1). In this paper, we describe the optimization of compound 1, which led to the design and synthesis of pyridyltriazine 31, a potent pan inhibitor of class I PI3Ks with a superior pharmacokinetic profile. Compound 31 was shown to potently block the targeted PI3K pathway in a mouse liver pharmacodynamic model and inhibit tumor growth in a U87 malignant glioma glioblastoma xenograft model. On the basis of its excellent in vivo efficacy and pharmacokinetic profile, compound 31 was selected for further evaluation as a clinical candidate and was designated AMG 511.

Synthesis and structure-activity relationships of dual PI3K/mTOR inhibitors based on a 4-amino-6-methyl-1,3,5-triazine sulfonamide scaffold.

Phosphoinositide 3-kinase (PI3K) is an important target in oncology due to the deregulation of the PI3K/Akt signaling pathway in a wide variety of tumors. A series of 4-amino-6-methyl-1,3,5-triazine sulfonamides were synthesized and evaluated as inhibitors of PI3K. The synthesis, in vitro biological activities, pharmacokinetic and in vivo pharmacodynamic profiling of these compounds are described. The most promising compound from this investigation (compound 3j) was found to be a pan class I PI3K inhibitor with a moderate (>10-fold) selectivity over the mammalian target of rapamycin (mTOR) in the enzyme assay. In a U87 MG cellular assay measuring phosphorylation of Akt, compound 3j displayed low double digit nanomolar IC(50) and exhibited good oral bioavailability in rats (F(oral)=63%). Compound 3j also showed a dose dependent reduction in the phosphorylation of Akt in a U87 tumor pharmacodynamic model with a plasma EC(50)=193 nM (91 ng/mL).

Structure-based design of a novel series of potent, selective inhibitors of the class I phosphatidylinositol 3-kinases.

A highly selective series of inhibitors of the class I phosphatidylinositol 3-kinases (PI3Ks) has been designed and synthesized. Starting from the dual PI3K/mTOR inhibitor 5, a structure-based approach was used to improve potency and selectivity, resulting in the identification of 54 as a potent inhibitor of the class I PI3Ks with excellent selectivity over mTOR, related phosphatidylinositol kinases, and a broad panel of protein kinases. Compound 54 demonstrated a robust PD-PK relationship inhibiting the PI3K/Akt pathway in vivo in a mouse model, and it potently inhibited tumor growth in a U-87 MG xenograft model with an activated PI3K/Akt pathway.

Fused piperidines as a novel class of potent and orally available transient receptor potential melastatin type 8 (TRPM8) antagonists.

The transient receptor potential melastatin type 8 (TRPM8) is a nonselective cation channel primarily expressed in a subpopulation of sensory neurons that can be activated by a wide range of stimuli, including menthol, icilin, and cold temperatures (<25 °C). Antagonism of TRPM8 is currently under investigation as a new approach for the treatment of pain. As a result of our screening efforts, we identified tetrahydrothienopyridine 4 as an inhibitor of icilin-induced calcium influx in CHO cells expressing recombinant rat TRPM8. Exploration of the structure-activity relationships of 4 led to the identification of a potent and orally bioavailable TRPM8 antagonist, tetrahydroisoquinoline 87. Compound 87 demonstrated target coverage in vivo after oral administration in a rat pharmacodynamic model measuring the prevention of icilin-induced wet-dog shakes (WDS).

Phospshoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) dual inhibitors: discovery and structure-activity relationships of a series of quinoline and quinoxaline derivatives.

The phosphoinositide 3-kinase (PI3K) family catalyzes the ATP-dependent phosphorylation of the 3'-hydroxyl group of phosphatidylinositols and plays an important role in cell growth and survival. There is abundant evidence demonstrating that PI3K signaling is dysregulated in many human cancers, suggesting that therapeutics targeting the PI3K pathway may have utility for the treatment of cancer. Our efforts to identify potent, efficacious, and orally available PI3K/mammalian target of rapamycin (mTOR) dual inhibitors resulted in the discovery of a series of substituted quinolines and quinoxalines derivatives. In this report, we describe the structure-activity relationships, selectivity, and pharmacokinetic data of this series and illustrate the in vivo pharmacodynamic and efficacy data for a representative compound.

Substituted aryl pyrimidines as potent and soluble TRPV1 antagonists.

Clinical candidate AMG 517 (1) is a potent antagonist toward multiple modes of activation of TRPV1; however, it suffers from poor solubility. Analogs with various substituents at the R region of 3 were prepared to improve the solubility while maintaining the potent TRPV1 activity of 1. Compounds were identified that maintained potency, had good pharmacokinetic properties, and improved solubility relative to 1.

Novel vanilloid receptor-1 antagonists: 1. Conformationally restricted analogues of trans-cinnamides.

The vanilloid receptor-1 (VR1 or TRPV1) is a member of the transient receptor potential (TRP) family of ion channels and plays a role as an integrator of multiple pain-producing stimuli. From a high-throughput screening assay, measuring calcium uptake in TRPV1-expressing cells, we identified an N-aryl trans-cinnamide (AMG9810, compound 9) that acts as a potent TRPV1 antagonist. We have demonstrated the antihyperalgesic properties of 9 in vivo and have also reported the discovery of novel, orally bioavailable cinnamides derived from this lead. Herein, we expand our investigations and describe the synthesis and biological evaluation of a series of conformationally constrained analogues of the s-cis conformer of compound 9. These investigations resulted in the identification of 4-amino- and 4-oxopyrimidine cores as suitable isosteric replacements for the trans-acrylamide moiety. The best examples from this series, pyrimidines 79 and 74, were orally bioavailable and exhibited potent antagonism of both rat (IC50 = 4.5 and 0.6 nM, respectively) and human TRPV1 (IC50 = 7.4 and 3.7 nM, respectively). In addition, compound 74 was shown to be efficacious at blocking a TRPV1-mediated physiological response in vivo in the capsaicin-induced hypothermia model in rats; however, it was ineffective at preventing thermal hyperalgesia induced by complete Freund's adjuvant in rats.

Novel vanilloid receptor-1 antagonists: 2. Structure-activity relationships of 4-oxopyrimidines leading to the selection of a clinical candidate.

A series of novel 4-oxopyrimidine TRPV1 antagonists was evaluated in assays measuring the blockade of capsaicin or acid-induced influx of calcium into CHO cells expressing TRPV1. The investigation of the structure-activity relationships in the heterocyclic A-region revealed the optimum pharmacophoric elements required for activity in this series and resulted in the identification of subnanomolar TRPV1 antagonists. The most potent of these antagonists were thoroughly profiled in pharmacokinetic assays. Optimization of the heterocyclic A-region led to the design and synthesis of 23, a compound that potently blocked multiple modes of TRPV1 activation. Compound 23 was shown to be effective in a rodent "on-target" biochemical challenge model (capsaicin-induced flinch, ED50 = 0.33 mg/kg p.o.) and was antihyperalgesic in a model of inflammatory pain (CFA-induced thermal hyperalgesia, MED = 0.83 mg/kg, p.o.). Based on its in vivo efficacy and pharmacokinetic profile, compound 23 (N-{4-[6-(4-trifluoromethyl-phenyl)-pyrimidin-4-yloxy]-benzothiazol-2-yl}-acetamide; AMG 517) was selected for further evaluation in human clinical trials.

Design of potent, orally available antagonists of the transient receptor potential vanilloid 1. Structure-activity relationships of 2-piperazin-1-yl-1H-benzimidazoles.

The vanilloid receptor-1 (VR1 or TRPV1) is a membrane-bound, nonselective cation channel that is predominantly expressed by peripheral neurons sensing painful stimuli. TRPV1 antagonists produce antihyperalgesic effects in animal models of inflammatory and neuropathic pain. Herein, we describe the synthesis and the structure-activity relationships of a series of 2-(4-pyridin-2-ylpiperazin-1-yl)-1H-benzo[d]imidazoles as novel TRPV1 antagonists. Compound 46ad was among the most potent analogues in this series. This compound was orally bioavailable in rats and was efficacious in blocking capsaicin-induced flinch in rats in a dose-dependent manner. Compound 46ad also reversed thermal hyperalgesia in a model of inflammatory pain, which was induced by complete Freund's adjuvant (CFA).

Synthesis and evaluation of thiazole carboxamides as vanilloid receptor 1 (TRPV1) antagonists.

A thiazole derivative, 2-(2,6-dichlorobenzyl)-N-(4-isopropylphenyl) thiazole-4-carboxamide (1), was identified as a TRPV1 antagonist. We synthesized various thiazole analogs and evaluated them for their ability to block capsaicin- or acid-induced calcium influx in TRPV1-expressing CHO cells. The IC(50) values of the most potent antagonists were ca. 0.050microM in these assays.

Melanocortin subtype-4 receptor agonists containing a piperazine core with substituted aryl sulfonamides.

The biological activity for a set of melanocortin-4 receptor (MC4R) agonists containing a piperazine core with an ortho-substituted aryl sulfonamide is described. Compounds from this set had binding and functional activities at MC4R less than 30 nM. The most selective compound in this series was >25,000-fold more potent at MC4R than MC3R, and 490-fold more potent at MC4R than MC5R. This compound also reduced food intake after oral dosing at 25, 50, and 100 mg kg(-1) in fasted mice.

Discovery of potent, orally available vanilloid receptor-1 antagonists. Structure-activity relationship of N-aryl cinnamides.

The vanilloid receptor-1 (TRPV1 or VR1) is a member of the transient receptor potential (TRP) family of ion channels and plays a role in regulating the function of sensory nerves. A growing body of evidence demonstrates the therapeutic potential of TRPV1 modulators, particularly in the management of pain. As a result of our screening efforts, we identified (E)-3-(4-tert-butylphenyl)-N-(2,3-dihydrobenzo[b][1,4]dioxin-6-yl)acrylamide (1), an antagonist that blocks the capsaicin-induced and pH-induced uptake of (45)Ca(2+) in TRPV1-expressing Chinese hamster ovary cells with IC(50) values of 17 +/- 5 and 150 +/- 80 nM, respectively. In this report, we describe the synthesis and structure-activity relationship of a series of N-aryl cinnamides, the most potent of which (49a and 49b) exhibit good oral bioavailability in rats (F(oral) = 39% and 17%, respectively).