RESUMO
Inhibitors of cyclin-dependent kinases (CDK) such as CDK2/cyclin A-E are currently undergoing clinical trials to verify their potential as new anticancer agents. In a previous article we described the lead discovery process of a 3-aminopyrazole class of CDK2/cyclin A-E inhibitors. The endpoint of this process was PNU-292137, a compound endowed with in vivo antitumor activity in a mouse tumor xenograft model. We optimized this lead compound to improve some physicochemical properties, notably solubility and plasma protein binding. This lead optimization process brought us to the discovery of (2S)-N-(5-cyclopropyl-1H-pyrazol-3-yl)-2-[4-(2-oxo-1-pyrrolidinyl)phenyl]propanamide (PHA-533533, 13), a compound with a balanced activity vs druglike profile. Compound 13 inhibited CDK2/cyclin A with a K(i) of 31 nM, counteracting tumor cell proliferation of different cell lines with an IC(50) in the submicromolar range. Solubility was improved more than 10 times over the starting lead, while plasma protein binding was decreased from 99% to 74%. With exploitation of this globally enhanced in vitro profile, 13 was more active than PNU-292137 in vivo in the A2780 xenograft model showing a tumor growth inhibition of 70%. Proof of mechanism of action was obtained in vivo by immunohistochemical analysis of tumor slices of 13-treated vs untreated animals.
Assuntos
Antineoplásicos/síntese química , Quinases relacionadas a CDC2 e CDC28/antagonistas & inibidores , Ciclina A/antagonistas & inibidores , Pirazóis/síntese química , Pirrolidinonas/síntese química , Animais , Antineoplásicos/farmacocinética , Antineoplásicos/farmacologia , Proteínas Sanguíneas/metabolismo , Células CACO-2 , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Quinase 2 Dependente de Ciclina , Ensaios de Seleção de Medicamentos Antitumorais , Células HT29 , Hepatócitos/metabolismo , Humanos , Técnicas In Vitro , Camundongos , Camundongos Nus , Modelos Moleculares , Permeabilidade , Fosforilação , Ligação Proteica , Pirazóis/farmacocinética , Pirazóis/farmacologia , Pirrolidinonas/farmacocinética , Pirrolidinonas/farmacologia , Ratos , Proteína do Retinoblastoma/metabolismo , Solubilidade , Estereoisomerismo , Relação Estrutura-Atividade , Transplante HeterólogoRESUMO
Abnormal proliferation mediated by disruption of the normal cell cycle mechanisms is a hallmark of virtually all cancer cells. Compounds targeting complexes between cyclin-dependent kinases (CDK) and cyclins, such as CDK2/cyclin A and CDK2/cyclin E, and inhibiting their kinase activity are regarded as promising antitumor agents to complement the existing therapies. From a high-throughput screening effort, we identified a new class of CDK2/cyclin A/E inhibitors. The hit-to-lead expansion of this class is described. X-ray crystallographic data of early compounds in this series, as well as in vitro testing funneled for rapidly achieving in vivo efficacy, led to a nanomolar inhibitor of CDK2/cyclin A (N-(5-cyclopropyl-1H-pyrazol-3-yl)-2-(2-naphthyl)acetamide (41), PNU-292137, IC50 = 37 nM) with in vivo antitumor activity (TGI > 50%) in a mouse xenograft model at a dose devoid of toxic effects.