RESUMEN
The discovery of two histamine H(3) antagonist clinical candidates is disclosed. The pathway to identification of the two clinical candidates, 6 (PF-03654746) and 7 (PF-03654764) required five hypothesis driven design cycles. The key to success in identifying these clinical candidates was the development of a compound design strategy that leveraged medicinal chemistry knowledge and traditional assays in conjunction with computational and in vitro safety tools. Overall, clinical compounds 6 and 7 exceeded conservative safety margins and possessed optimal pharmacological and pharmacokinetic profiles, thus achieving our initial goal of identifying compounds with fully aligned oral drug attributes, "best-in-class" molecules.
Asunto(s)
Ciclobutanos/síntesis química , Diseño de Fármacos , Antagonistas de los Receptores Histamínicos/síntesis química , Pirrolidinas/síntesis química , Receptores Histamínicos H3/metabolismo , Animales , Proteínas Sanguíneas/metabolismo , Barrera Hematoencefálica/metabolismo , Línea Celular , Ciclobutanos/farmacología , Ciclobutanos/toxicidad , Perros , Conducta de Ingestión de Líquido/efectos de los fármacos , Ensayos Analíticos de Alto Rendimiento , Antagonistas de los Receptores Histamínicos/farmacología , Antagonistas de los Receptores Histamínicos/toxicidad , Humanos , Técnicas In Vitro , Riñón/metabolismo , Lipidosis/inducido químicamente , Lipidosis/metabolismo , Pulmón/metabolismo , Microsomas Hepáticos/efectos de los fármacos , Microsomas Hepáticos/metabolismo , Modelos Moleculares , Estructura Molecular , Fosfolípidos/metabolismo , Unión Proteica , Pirrolidinas/farmacología , Pirrolidinas/toxicidad , Ratas , Ratas Sprague-Dawley , Estereoisomerismo , Relación Estructura-ActividadRESUMEN
The circadian clock links our daily cycles of sleep and activity to the external environment. Deregulation of the clock is implicated in a number of human disorders, including depression, seasonal affective disorder, and metabolic disorders. Casein kinase 1 epsilon (CK1epsilon) and casein kinase 1 delta (CK1delta) are closely related Ser-Thr protein kinases that serve as key clock regulators as demonstrated by mammalian mutations in each that dramatically alter the circadian period. Therefore, inhibitors of CK1delta/epsilon may have utility in treating circadian disorders. Although we previously demonstrated that a pan-CK1delta/epsilon inhibitor, 4-[3-cyclohexyl-5-(4-fluoro-phenyl)-3H-imidazol-4-yl]-pyrimidin-2-ylamine (PF-670462), causes a significant phase delay in animal models of circadian rhythm, it remains unclear whether one of the kinases has a predominant role in regulating the circadian clock. To test this, we have characterized 3-(3-chloro-phenoxymethyl)-1-(tetrahydro-pyran-4-yl)-1H-pyrazolo[3,4-d]pyrimidin-4-ylamine (PF-4800567), a novel and potent inhibitor of CK1epsilon (IC(50) = 32 nM) with greater than 20-fold selectivity over CK1delta. PF-4800567 completely blocks CK1epsilon-mediated PER3 nuclear localization and PER2 degradation. In cycling Rat1 fibroblasts and a mouse model of circadian rhythm, however, PF-4800567 has only a minimal effect on the circadian clock at concentrations substantially over its CK1epsilon IC(50). This is in contrast to the pan-CK1delta/epsilon inhibitor PF-670462 that robustly alters the circadian clock under similar conditions. These data indicate that CK1epsilon is not the predominant mediator of circadian timing relative to CK1delta. PF-4800567 should prove useful in probing unique roles between these two kinases in multiple signaling pathways.