RESUMEN
The αvß6 integrin plays a key role in the activation of transforming growth factor-ß (TGFß), a pro-fibrotic mediator that is pivotal to the development of idiopathic pulmonary fibrosis (IPF). We identified a selective small molecule αvß6 RGD-mimetic, GSK3008348, and profiled it in a range of disease relevant pre-clinical systems. To understand the relationship between target engagement and inhibition of fibrosis, we measured pharmacodynamic and disease-related end points. Here, we report, GSK3008348 binds to αvß6 with high affinity in human IPF lung and reduces downstream pro-fibrotic TGFß signaling to normal levels. In human lung epithelial cells, GSK3008348 induces rapid internalization and lysosomal degradation of the αvß6 integrin. In the murine bleomycin-induced lung fibrosis model, GSK3008348 engages αvß6, induces prolonged inhibition of TGFß signaling and reduces lung collagen deposition and serum C3M, a marker of IPF disease progression. These studies highlight the potential of inhaled GSK3008348 as an anti-fibrotic therapy.
Asunto(s)
Butiratos/farmacología , Fibrosis Pulmonar Idiopática/tratamiento farmacológico , Integrinas/antagonistas & inhibidores , Naftiridinas/farmacología , Pirazoles/farmacología , Pirrolidinas/farmacología , Administración por Inhalación , Animales , Antígenos de Neoplasias/metabolismo , Bleomicina/toxicidad , Butiratos/administración & dosificación , Butiratos/metabolismo , Butiratos/farmacocinética , Colágeno/metabolismo , Modelos Animales de Enfermedad , Células Epiteliales/efectos de los fármacos , Humanos , Fibrosis Pulmonar Idiopática/inducido químicamente , Fibrosis Pulmonar Idiopática/patología , Integrinas/metabolismo , Masculino , Ratones Endogámicos C57BL , Simulación del Acoplamiento Molecular , Naftiridinas/administración & dosificación , Naftiridinas/metabolismo , Naftiridinas/farmacocinética , Pirazoles/administración & dosificación , Pirazoles/metabolismo , Pirazoles/farmacocinética , Pirrolidinas/administración & dosificación , Pirrolidinas/metabolismo , Pirrolidinas/farmacocinética , Bibliotecas de Moléculas Pequeñas/química , Bibliotecas de Moléculas Pequeñas/farmacología , Tomografía Computarizada de Emisión de Fotón Único , Factor de Crecimiento Transformador beta/metabolismo , Investigación Biomédica TraslacionalRESUMEN
The alpha-v beta-6 (αvß6) integrin has been identified as playing a key role in the activation of transforming growth factor-ß (TGFß) that is hypothesised to be pivotal in the development of cancer and fibrotic diseases. Therefore, the αvß6 integrin is an attractive therapeutic target for these debilitating diseases and a drug discovery programme to identify small molecule αvß6 selective arginyl-glycinyl-aspartic acid (RGD)-mimetics was initiated within GlaxoSmithKline. The primary aim of this study was to pharmacologically characterise the binding to αvß6 of a novel clinical candidate, compound 1, using a radiolabelled form. Radioligand binding studies were completed with [(3)H]compound 1 against the human and mouse soluble protein forms of αvß6 to determine accurate affinity estimates and binding kinetics. The selectivity of compound 1 for the RGD integrin family was also determined using saturation binding studies (αvß1, αvß3, αvß5, αvß8, α5ß1 and α8ß1 integrins) and fibrinogen-induced platelet aggregation (αIIbß3 integrin). In addition, the relationship between divalent metal cation type and concentration and αvß6 RGD site binding was also investigated. Compound 1 has been demonstrated to bind with extremely high affinity and selectivity for the αvß6 integrin and has the potential as a clinical tool and therapeutic for investigating the role of αvß6 in a range of disease states both pre-clinically and clinically. In addition, this is the first study that has successfully applied radioligand binding to the RGD integrin field to accurately determine the affinity and selectivity profile of a small molecule RGD-mimetic.
