RESUMEN
Despite abundant evidence that aberrant Rho-family GTPase activation contributes to most steps of cancer initiation and progression, there is a dearth of inhibitors of their effectors (e.g., p21-activated kinases). Through high-throughput screening and structure-based design, we identify PF-3758309, a potent (K(d) = 2.7 nM), ATP-competitive, pyrrolopyrazole inhibitor of PAK4. In cells, PF-3758309 inhibits phosphorylation of the PAK4 substrate GEF-H1 (IC(50) = 1.3 nM) and anchorage-independent growth of a panel of tumor cell lines (IC(50) = 4.7 +/- 3 nM). The molecular underpinnings of PF-3758309 biological effects were characterized using an integration of traditional and emerging technologies. Crystallographic characterization of the PF-3758309/PAK4 complex defined determinants of potency and kinase selectivity. Global high-content cellular analysis confirms that PF-3758309 modulates known PAK4-dependent signaling nodes and identifies unexpected links to additional pathways (e.g., p53). In tumor models, PF-3758309 inhibits PAK4-dependent pathways in proteomic studies and regulates functional activities related to cell proliferation and survival. PF-3758309 blocks the growth of multiple human tumor xenografts, with a plasma EC(50) value of 0.4 nM in the most sensitive model. This study defines PAK4-related pathways, provides additional support for PAK4 as a therapeutic target with a unique combination of functions (apoptotic, cytoskeletal, cell-cycle), and identifies a potent, orally available small-molecule PAK inhibitor with significant promise for the treatment of human cancers.
Asunto(s)
Proliferación Celular/efectos de los fármacos , Modelos Moleculares , Neoplasias/metabolismo , Pirazoles/farmacología , Pirroles/farmacología , Transducción de Señal/efectos de los fármacos , Quinasas p21 Activadas/antagonistas & inhibidores , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Cristalografía , Factores de Intercambio de Guanina Nucleótido/metabolismo , Humanos , Neoplasias/tratamiento farmacológico , Fosforilación/efectos de los fármacos , Pirazoles/química , Pirazoles/metabolismo , Pirroles/química , Pirroles/metabolismo , Factores de Intercambio de Guanina Nucleótido RhoRESUMEN
Lead optimization efforts that employed structure base drug design and physicochemical property based optimization leading to the discovery of a novel series of 4-methylpyrido pyrimidinone (MPP) are discussed. Synthesis and profile of 1, a PI3Kα/mTOR dual inhibitor, is highlighted.
Asunto(s)
Diseño de Fármacos , Inhibidores de las Quinasa Fosfoinosítidos-3 , Inhibidores de Proteínas Quinasas/síntesis química , Piridonas/química , Pirimidinas/química , Pirimidinonas/química , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Animales , Sitios de Unión , Cristalografía por Rayos X , Semivida , Humanos , Ratones , Microsomas Hepáticos/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Inhibidores de Proteínas Quinasas/química , Inhibidores de Proteínas Quinasas/farmacocinética , Estructura Terciaria de Proteína , Piridonas/síntesis química , Piridonas/farmacocinética , Pirimidinas/síntesis química , Pirimidinas/farmacocinética , Pirimidinonas/síntesis química , Pirimidinonas/farmacocinética , Pirrolidinas/química , Ratas , Relación Estructura-Actividad , Serina-Treonina Quinasas TOR/metabolismoRESUMEN
PI3K, AKT, and mTOR are key kinases from PI3K signaling pathway being extensively pursued to treat a variety of cancers in oncology. To search for a structurally differentiated back-up candidate to PF-04691502, which is currently in phase I/II clinical trials for treating solid tumors, a lead optimization effort was carried out with a tricyclic imidazo[1,5]naphthyridine series. Integration of structure-based drug design and physical properties-based optimization yielded a potent and selective PI3K/mTOR dual kinase inhibitor PF-04979064. This manuscript discusses the lead optimization for the tricyclic series, which both improved the in vitro potency and addressed a number of ADMET issues including high metabolic clearance mediated by both P450 and aldehyde oxidase (AO), poor permeability, and poor solubility. An empirical scaling tool was developed to predict human clearance from in vitro human liver S9 assay data for tricyclic derivatives that were AO substrates.
RESUMEN
The P21-activated kinases (PAK) are emerging antitumor therapeutic targets. In this paper, we describe the discovery of potent PAK inhibitors guided by structure-based drug design. In addition, the efflux of the pyrrolopyrazole series was effectively reduced by applying multiple medicinal chemistry strategies, leading to a series of PAK inhibitors that are orally active in inhibiting tumor growth in vivo.