RESUMEN
A second-generation small molecule P2X3 receptor antagonist has been developed. The lead optimization strategy to address shortcomings of the first-generation preclinical lead compound is described herein. These studies were directed towards the identification and amelioration of preclinical hepatobiliary findings, reducing potential for drug-drug interactions, and decreasing the projected human dose of the first-generation lead.
Asunto(s)
Analgésicos/uso terapéutico , Benzamidas/uso terapéutico , Dolor/tratamiento farmacológico , Antagonistas del Receptor Purinérgico P2X/uso terapéutico , Piridinas/uso terapéutico , Receptores Purinérgicos P2X3/metabolismo , Analgésicos/síntesis química , Analgésicos/química , Analgésicos/farmacocinética , Animales , Benzamidas/síntesis química , Benzamidas/química , Benzamidas/farmacocinética , Perros , Diseño de Fármacos , Interacciones Farmacológicas , Glucuronosiltransferasa/antagonistas & inhibidores , Semivida , Hiperbilirrubinemia/prevención & control , Estructura Molecular , Antagonistas del Receptor Purinérgico P2X/síntesis química , Antagonistas del Receptor Purinérgico P2X/química , Antagonistas del Receptor Purinérgico P2X/farmacocinética , Piridinas/síntesis química , Piridinas/química , Piridinas/farmacocinética , Ratas , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
The IC50 of a beta-secretase (BACE-1) lead compound was improved â¼200-fold from 11 µM to 55 nM through the addition of a single methyl group. Computational chemistry, small molecule NMR, and protein crystallography capabilities were used to compare the solution conformation of the ligand under varying pH conditions to its conformation when bound in the active site. Chemical modification then explored available binding pockets adjacent to the ligand. A strategically placed methyl group not only maintained the required pKa of the piperidine nitrogen and filled a small hydrophobic pocket, but more importantly, stabilized the conformation best suited for optimized binding to the receptor.
Asunto(s)
Secretasas de la Proteína Precursora del Amiloide/antagonistas & inhibidores , Ácido Aspártico Endopeptidasas/antagonistas & inhibidores , Hidantoínas/química , Hidantoínas/farmacología , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Ácido Aspártico Endopeptidasas/metabolismo , Cristalografía por Rayos X , Relación Dosis-Respuesta a Droga , Humanos , Hidantoínas/síntesis química , Metilación , Modelos Moleculares , Estructura Molecular , Relación Estructura-ActividadRESUMEN
Rational modification of the potent calcitonin gene-related peptide (CGRP) receptor antagonist MK-3207 led to a series of analogues with enhanced CNS penetrance and a convenient chemical handle for introduction of a radiolabel. A number of (11)C-tracers were synthesized and evaluated in vivo, leading to the identification of [(11)C]8 ([(11)C]MK-4232), the first positron emission tomography tracer for the CGRP receptor.
RESUMEN
Rational modification of the clinically tested CGRP receptor antagonist MK-3207 (3) afforded an analogue with increased unbound fraction in rat plasma and enhanced aqueous solubility, 2-[(8R)-8-(3,5-difluorophenyl)-8-methyl-10-oxo-6,9-diazaspiro[4.5]dec-9-yl]-N-[(6S)-2'-oxo-1',2',5,7-tetrahydrospiro[cyclopenta[b]pyridine-6,3'-pyrrolo[2,3-b]pyridin]-3-yl]acetamide (MK-8825) (6). Compound 6 maintained similar affinity to 3 at the human and rat CGRP receptors but possessed significantly improved in vivo potency in a rat pharmacodynamic model. The overall profile of 6 indicates it should find utility as a rat tool to investigate effects of CGRP receptor blockade in vivo.
Asunto(s)
Analgésicos/síntesis química , Analgésicos/farmacología , Antagonistas del Receptor Peptídico Relacionado con el Gen de la Calcitonina , Trastornos Migrañosos/tratamiento farmacológico , Piridinas/síntesis química , Piridinas/farmacología , Compuestos de Espiro/síntesis química , Compuestos de Espiro/farmacología , Administración Oral , Analgésicos/sangre , Animales , Disponibilidad Biológica , Modelos Animales de Enfermedad , Perros , Humanos , Macaca mulatta , Ratones , Piridinas/sangre , Ratas , Receptores de Péptido Relacionado con el Gen de Calcitonina/metabolismo , Especificidad de la Especie , Compuestos de Espiro/sangreRESUMEN
We have developed a novel series of pyrrolidine derived BACE-1 inhibitors. The potency of the weak initial lead structure was enhanced using library-based SAR methods. The series was then further advanced by rational design while maintaining a minimal ligand binding efficiency threshold. Ultimately, the co-crystal structure was obtained revealing that these inhibitors interacted with the enzyme in a unique fashion. In all, the potency of the series was enhanced by 4 orders of magnitude from the HTS lead with concomitant increases in physical properties needed for series advancement. The progression of these developments in a systematic fashion is described.
Asunto(s)
Secretasas de la Proteína Precursora del Amiloide/metabolismo , Química Farmacéutica/métodos , Pirrolidinas/farmacología , Secretasas de la Proteína Precursora del Amiloide/antagonistas & inhibidores , Ácido Aspártico Endopeptidasas/antagonistas & inhibidores , Cristalización , Cristalografía por Rayos X/métodos , Diseño de Fármacos , Inhibidores Enzimáticos/farmacología , Concentración 50 Inhibidora , Ligandos , Modelos Químicos , Unión Proteica , Relación Estructura-ActividadRESUMEN
Identification of an HIV integrase inhibitor with micromolar affinity for the CGRP receptor led to the discovery of a series of structurally novel CGRP receptor antagonists. Optimization of this series produced compound 16, a low-molecular weight CGRP receptor antagonist with good pharmacokinetic properties in both rat and dog. In contrast to other nonpeptide antagonists, the activity of 16 was affected by the presence of divalent cations and showed evidence of an alternative, RAMP-independent CGRP receptor binding site.
Asunto(s)
Antagonistas del Receptor Peptídico Relacionado con el Gen de la Calcitonina , Inhibidores de Integrasa VIH/química , Inhibidores de Integrasa VIH/farmacología , Piridinas/química , Piridinas/farmacología , Proteínas Modificadoras de la Actividad de Receptores/metabolismo , Receptores de Péptido Relacionado con el Gen de Calcitonina/metabolismo , Animales , Línea Celular , Perros , VIH/enzimología , Inhibidores de Integrasa VIH/farmacocinética , Humanos , Unión Proteica , Piridinas/farmacocinética , RatasRESUMEN
A novel series of potent CGRP receptor antagonists containing a central quinoline ring constraint was identified. The combination of the quinoline constraint with a tricyclic benzimidazolinone left hand fragment produced an analog with picomolar potency (14, CGRP K(i)=23 pM). Further optimization of the tricycle produced a CGRP receptor antagonist that exhibited subnanomolar potency (19, CGRP K(i)=0.52 nM) and displayed a good pharmacokinetic profile in three preclinical species.
Asunto(s)
Antagonistas del Receptor Peptídico Relacionado con el Gen de la Calcitonina , Quinolinas/farmacología , Animales , Disponibilidad Biológica , Perros , Evaluación Preclínica de Medicamentos , Macaca mulatta , Quinolinas/química , Quinolinas/farmacocinética , RatasRESUMEN
This Letter describes the one pot synthesis of tertiary carbinamine 3 and related analogs of brain penetrant BACE-1 inhibitors via the alkylation of the Schiff base intermediate 2. The methodology developed for this study provided a convenient and rapid means to explore the P1 region of these types of inhibitors, where the P1 group is installed in the final step using a one-pot two-step protocol. Further SAR studies led to the identification of 10 which is twofold more potent in vitro as compared to the lead compound. This inhibitor was characterized in a cisterna magna ported rhesus monkey model, where significant lowering of CSF Abeta40 was observed.
Asunto(s)
Secretasas de la Proteína Precursora del Amiloide/antagonistas & inhibidores , Ácido Aspártico Endopeptidasas/antagonistas & inhibidores , Encéfalo/enzimología , Inhibidores Enzimáticos/química , Oxadiazoles/química , Sulfonamidas/química , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Péptidos beta-Amiloides/metabolismo , Animales , Ácido Aspártico Endopeptidasas/metabolismo , Encéfalo/metabolismo , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/farmacocinética , Humanos , Macaca mulatta , Oxadiazoles/síntesis química , Oxadiazoles/farmacocinética , Fragmentos de Péptidos/metabolismo , Relación Estructura-Actividad , Sulfonamidas/síntesis química , Sulfonamidas/farmacocinéticaRESUMEN
Calcitonin gene-related peptide (CGRP) has long been hypothesized to play a key role in migraine pathophysiology, and the advent of small-molecule antagonists has clearly demonstrated a clinical link between blocking the CGRP receptor and migraine efficacy. 2-[(8R)-8-(3,5-Difluorophenyl)-10-oxo-6,9-diazaspiro[4.5]dec-9-yl]-N-[(2R)-2'-oxo-1,1',2',3-tetrahydrospiro[indene-2,3'-pyrrolo[2,3-b]pyridin]-5-yl]acetamide (MK-3207) represents the third CGRP receptor antagonist to display clinical efficacy in migraine trials. Here, we report the pharmacological characterization of MK-3207, a potent and orally bioavailable CGRP receptor antagonist. In vitro, MK-3207 is a potent antagonist of the human and rhesus monkey CGRP receptors (K(i) = 0.024 nM). In common with other CGRP receptor antagonists, MK-3207 displays lower affinity for CGRP receptors from other species, including canine and rodent. As a consequence of species selectivity, the in vivo potency was assessed in a rhesus monkey pharmacodynamic assay measuring capsaicin-induced changes in forearm dermal blood flow via laser Doppler imaging. MK-3207 produced a concentration-dependent inhibition of dermal vasodilation, with plasma concentrations of 0.8 and 7 nM required to block 50 and 90% of the blood flow increase, respectively. The tritiated analog [3H]MK-3207 was used to study the binding characteristics on the human CGRP receptor. [3H]MK-3207 displayed reversible and saturable binding (K(D) = 0.06 nM), and the off-rate was determined to be 0.012 min(-1), with a t(1/2) value of 59 min. In vitro autoradiography studies on rhesus monkey brain slices identified the highest level of binding in the cerebellum, brainstem, and meninges. Finally, as an index of central nervous system penetrability, the in vivo cerebrospinal fluid/plasma ratio was determined to be 2 to 3% in cisterna magna-ported rhesus monkeys.
Asunto(s)
Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Antagonistas del Receptor Peptídico Relacionado con el Gen de la Calcitonina , Compuestos de Espiro/farmacología , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/metabolismo , Animales , Autorradiografía , Unión Competitiva , Transporte Biológico , Encéfalo/metabolismo , Compuestos Bicíclicos Heterocíclicos con Puentes/sangre , Compuestos Bicíclicos Heterocíclicos con Puentes/líquido cefalorraquídeo , Línea Celular , Chlorocebus aethiops , Femenino , Humanos , Cinética , Macaca mulatta , Masculino , Ratones , Ensayo de Unión Radioligante , Receptores de Adrenomedulina , Receptores de Calcitonina/metabolismo , Receptores de Péptido Relacionado con el Gen de Calcitonina/fisiología , Receptores de Polipéptido Amiloide de Islotes Pancreáticos , Receptores de Péptidos/metabolismo , Compuestos de Espiro/sangre , Compuestos de Espiro/líquido cefalorraquídeo , Vasodilatación/efectos de los fármacosRESUMEN
During our ongoing efforts to develop a small molecule inhibitor targeting the beta-amyloid cleaving enzyme (BACE-1), we discovered a class of compounds bearing an aminoimidazole motif. Initial optimization led to potent compounds that have high Pgp efflux ratios. Crystal structure-aided design furnished conformationally constrained compounds that are both potent and have relatively low Pgp efflux ratios. Computational studies performed after these optimizations suggest that the introduction of the constraint enhances potency via additional hydrophobic interactions rather than conformational restriction.
Asunto(s)
Secretasas de la Proteína Precursora del Amiloide/antagonistas & inhibidores , Imidazoles/química , Inhibidores de Proteasas/química , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/metabolismo , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Sitios de Unión , Dominio Catalítico , Cristalografía por Rayos X , Diseño de Fármacos , Humanos , Imidazoles/síntesis química , Imidazoles/farmacología , Conformación Molecular , Inhibidores de Proteasas/síntesis química , Inhibidores de Proteasas/farmacología , Estructura Terciaria de ProteínaRESUMEN
A series of tricyclic CGRP receptor antagonists was optimized in order to improve oral bioavailability. Attenuation of polar surface area and incorporation of a weakly basic indoline nitrogen led to compound 5, a potent antagonist with good oral bioavailability in three species.
Asunto(s)
Antagonistas del Receptor Peptídico Relacionado con el Gen de la Calcitonina , Compuestos Heterocíclicos con 3 Anillos/farmacocinética , Compuestos de Espiro/farmacocinética , Administración Oral , Animales , Disponibilidad Biológica , Línea Celular , Perros , Haplorrinos , Compuestos Heterocíclicos con 3 Anillos/administración & dosificación , Compuestos Heterocíclicos con 3 Anillos/química , Humanos , Ratas , Receptores de Péptido Relacionado con el Gen de Calcitonina/metabolismo , Compuestos de Espiro/administración & dosificaciónRESUMEN
Brain penetration of drugs which are subject to P-glycoprotein (Pgp)-mediated efflux is attenuated, as manifested by the fact that the cerebrospinal fluid concentration (C(CSF)), a good surrogate of the unbound brain concentration (C(ub)), is lower than the unbound plasma concentration (C(up)) for Pgp substrates. In rodents, the attenuation magnitude of brain penetration by Pgp-mediated efflux has been estimated by correlating the ratio of CSF to plasma exposures (C(CSF)/C(p)) with the unbound fraction in plasma (f(u)) upon the incorporation of the in vivo or in vitro Pgp-mediated efflux ratios (ERs). In the present work, we investigated the impact of Pgp-mediated efflux on C(CSF) in monkeys. Following intravenous administration to cisterna magna ported rhesus monkeys, the CSF and plasma concentrations were determined for 25 compounds from three discovery programs. We also evaluated their f(u) in rhesus plasma and ER in human and African green monkey MDR-transfected LLC-PK1 cells. These compounds varied significantly in the f(u) (0.025-0.73), and 24 out of 25 are considered Pgp substrates based on their appreciable directional transport (ER>2). The C(CSF)/C(p) was significantly lower than the corresponding f(u) (>or=3-fold) for 16 compounds regardless of a significant correlation (R(2)=0.59, p=4 x 10(-5)) when the C(CSF)/C(p) was plotted against the f(u). When the f(u) was normalized to the ER (f(u)/ER) the correlation was improved (R(2)=0.75, p=8 x 10(-8)). More importantly, only one compound showed the C(CSF)/C(p) that exceeded 3-fold of the normalized f(u). The results suggest that the impact of Pgp-mediated efflux in monkeys, similar to the case in rodents, is reasonably reflected by the gradient between the free concentrations in plasma and in CSF. Therefore, f(u) and Pgp ER may serve as useful measurements in estimating in vivo C(CSF)/C(p) ratios in monkeys, and potentially in humans.
Asunto(s)
Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/farmacología , Transporte Biológico/efectos de los fármacos , Barrera Hematoencefálica/fisiología , Encéfalo/efectos de los fármacos , Plasma/efectos de los fármacos , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/genética , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/metabolismo , Animales , Transporte Biológico/fisiología , Proteínas Sanguíneas/metabolismo , Encéfalo/metabolismo , Células Cultivadas , Humanos , Macaca mulatta , Masculino , Peso Molecular , Compuestos Orgánicos/síntesis química , Compuestos Orgánicos/metabolismo , Plasma/química , TransfecciónRESUMEN
We have developed a novel series of heteroaromatic BACE-1 inhibitors. These inhibitors interact with the enzyme in a unique fashion that allows for potent binding in a non-traditional paradigm. In addition to the elucidation of their binding profile, we have discovered a pH dependent effect on the binding affinity as a result of the intrinsic pK(a) of these inhibitors and the pH of the BACE-1 enzyme binding assay.
Asunto(s)
Secretasas de la Proteína Precursora del Amiloide/antagonistas & inhibidores , Inhibidores Enzimáticos/química , Compuestos Heterocíclicos/química , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Cristalografía por Rayos X , Diseño de Fármacos , Inhibidores Enzimáticos/farmacología , Compuestos Heterocíclicos/farmacología , Concentración de Iones de Hidrógeno , Unión Proteica , Relación Estructura-ActividadRESUMEN
A small molecule inhibitor of beta-secretase with a unique binding mode has been developed. Crystallographic determination of the enzyme-inhibitor complex shows the catalytic aspartate residues in the active site are not engaged in inhibitor binding. This unprecedented binding mode in the field of aspartyl protease inhibition is described.
Asunto(s)
Secretasas de la Proteína Precursora del Amiloide/antagonistas & inhibidores , Ácido Aspártico , Inhibidores Enzimáticos/farmacocinética , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Ácido Aspártico Endopeptidasas/antagonistas & inhibidores , Ácido Aspártico Endopeptidasas/metabolismo , Dominio Catalítico , Cristalografía por Rayos X , Inhibidores Enzimáticos/química , Unión ProteicaAsunto(s)
Aminas/química , Secretasas de la Proteína Precursora del Amiloide/antagonistas & inhibidores , Péptidos beta-Amiloides/líquido cefalorraquídeo , Fragmentos de Péptidos/líquido cefalorraquídeo , Inhibidores de Proteasas/química , Administración Oral , Aminas/administración & dosificación , Aminas/farmacología , Secretasas de la Proteína Precursora del Amiloide/química , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Animales , Barrera Hematoencefálica , Cristalografía por Rayos X , Haplorrinos , Concentración 50 Inhibidora , Macaca mulatta , Conformación Molecular , Inhibidores de Proteasas/administración & dosificación , Inhibidores de Proteasas/farmacología , Relación Estructura-ActividadRESUMEN
beta-Site amyloid precursor protein (APP)-cleaving enzyme (BACE) 1 cleavage of amyloid precursor protein is an essential step in the generation of the potentially neurotoxic and amyloidogenic A beta 42 peptides in Alzheimer's disease. Although previous mouse studies have shown brain A beta lowering after BACE1 inhibition, extension of such studies to nonhuman primates or man was precluded by poor potency, brain penetration, and pharmacokinetics of available inhibitors. In this study, a novel tertiary carbinamine BACE1 inhibitor, tertiary carbinamine (TC)-1, was assessed in a unique cisterna magna ported rhesus monkey model, where the temporal dynamics of A beta in cerebrospinal fluid (CSF) and plasma could be evaluated. TC-1, a potent inhibitor (IC(50) approximately 0.4 nM), has excellent passive membrane permeability, low susceptibility to P-glycoprotein transport, and lowered brain A beta levels in a mouse model. Intravenous infusion of TC-1 led to a significant but transient lowering of CSF and plasma A beta levels in conscious rhesus monkeys because it underwent CYP3A4-mediated metabolism. Oral codosing of TC-1 with ritonavir, a potent CYP3A4 inhibitor, twice daily over 3.5 days in rhesus monkeys led to sustained plasma TC-1 exposure and a significant and sustained reduction in CSF sAPP beta, A beta 40, A beta 42, and plasma A beta 40 levels. CSF A beta 42 lowering showed an EC(50) of approximately 20 nM with respect to the CSF [TC-1] levels, demonstrating excellent concordance with its potency in a cell-based assay. These results demonstrate the first in vivo proof of concept of CSF A beta lowering after oral administration of a BACE1 inhibitor in a nonhuman primate.
Asunto(s)
Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/genética , Secretasas de la Proteína Precursora del Amiloide/antagonistas & inhibidores , Precursor de Proteína beta-Amiloide/líquido cefalorraquídeo , Precursor de Proteína beta-Amiloide/antagonistas & inhibidores , Animales , Ácido Aspártico Endopeptidasas/antagonistas & inhibidores , Inhibidores Enzimáticos/administración & dosificación , Inhibidores Enzimáticos/farmacología , Humanos , Infusiones Intravenosas , Macaca mulatta , Ratones , Ratones Transgénicos , TransfecciónRESUMEN
Rational modification of a previously identified spirohydantoin lead structure has identified a series of potent spiroazaoxindole CGRP receptor antagonists. The azaoxindole was found to be a general replacement for the hydantoin that consistently improved in vitro potency. The combination of the indanylspiroazaoxindole and optimized benzimidazolinones led to highly potent antagonists (e.g., 25, CGRP K(i)=40pM). The closely related compound 27 demonstrated good oral bioavailability in dog and rhesus.
Asunto(s)
Antagonistas del Receptor Peptídico Relacionado con el Gen de la Calcitonina , Indoles/síntesis química , Compuestos de Espiro/síntesis química , Administración Oral , Animales , Disponibilidad Biológica , Perros , Descubrimiento de Drogas , Humanos , Indoles/farmacología , Macaca mulatta , Oxindoles , Compuestos de Espiro/farmacología , Relación Estructura-ActividadRESUMEN
The previously disclosed spirohydantoin-based CGRP receptor antagonists were optimized for potency through modification of the benzimidazolone substituents. Compounds were identified which had minimal shift in the cAMP functional assay containing 50% human serum. Blockade of CGRP-mediated vasodilation was observed with these compounds in a rhesus pharmacodynamic assay and the in vivo potency correlated with the in vitro activity in the serum-shifted functional assay.
Asunto(s)
Bencimidazoles/síntesis química , Bencimidazoles/farmacología , Antagonistas del Receptor Peptídico Relacionado con el Gen de la Calcitonina , Indanos/química , Compuestos de Espiro/síntesis química , Compuestos de Espiro/farmacología , Animales , Bencimidazoles/sangre , Bencimidazoles/química , Técnicas Químicas Combinatorias , Humanos , Macaca mulatta , Estructura Molecular , Compuestos de Espiro/química , Relación Estructura-ActividadRESUMEN
A high-throughput screen at 100 microM inhibitor concentration for the BACE-1 enzyme revealed a novel spiropiperidine iminohydantoin aspartyl protease inhibitor template. An X-ray cocrystal structure with BACE-1 revealed a novel mode of binding whereby the inhibitor interacts with the catalytic aspartates via bridging water molecules. Using the crystal structure as a guide, potent compounds with good brain penetration were designed.
Asunto(s)
Secretasas de la Proteína Precursora del Amiloide/antagonistas & inhibidores , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/farmacología , Imidazolidinas/síntesis química , Imidazolidinas/farmacología , Piperidinas/síntesis química , Piperidinas/farmacología , Secretasas de la Proteína Precursora del Amiloide/química , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Cristalografía por Rayos X , Evaluación Preclínica de Medicamentos , Inhibidores Enzimáticos/química , Enlace de Hidrógeno , Imidazolidinas/química , Modelos Moleculares , Estructura Molecular , Piperidinas/química , Relación Estructura-ActividadRESUMEN
Two novel routes have been developed to the (3 R,6 S)-3-amino-6-(2,3-difluorophenyl)-1-(2,2,2-trifluoroethyl)azepan-2-one 2 of the CGRP receptor antagonist clinical candidate telcagepant (MK-0974, 1). The first employs a ring-closing metathesis of the styrene 7 as the key reaction, while the second makes use of a highly diastereoselective Hayashi-Miyaura Rh-catalyzed arylboronic acid addition to nitroalkene 16. The latter route has been implemented to produce multigram quantities of telcagepant for extensive preclinical evaluation.