ABSTRACT
JAK1, JAK2, JAK3, and TYK2 belong to the JAK (Janus kinase) family. They play critical roles in cytokine signaling. Constitutive activation of JAK/STAT pathways is associated with a wide variety of diseases. Particularly, pSTAT3 is observed in response to the treatment with inhibitors of oncogenic signaling pathways such as EGFR, MAPK, and AKT and is associated with resistance or poorer response to agents targeting these pathways. Among the JAK family kinases, JAK1 has been shown to be the primary driver of STAT3 phosphorylation and signaling; therefore, selective JAK1 inhibition can be a viable means to overcome such treatment resistances. Herein, an account of the medicinal chemistry optimization from the promiscuous kinase screening hit 3 to the candidate drug 21 (AZD4205), a highly selective JAK1 kinase inhibitor, is reported. Compound 21 has good preclinical pharmacokinetics. Compound 21 displayed an enhanced antitumor activity in combination with an approved EGFR inhibitor, osimertinib, in a preclinical non-small-cell lung cancer (NSCLC) xenograft NCI-H1975 model.
Subject(s)
Indoles/therapeutic use , Janus Kinase 1/antagonists & inhibitors , Protein Kinase Inhibitors/therapeutic use , Acrylamides/pharmacology , Aniline Compounds/pharmacology , Animals , Cell Line, Tumor , Drug Design , Drug Discovery , Drug Screening Assays, Antitumor , Drug Synergism , ErbB Receptors/antagonists & inhibitors , Female , Humans , Indoles/chemical synthesis , Indoles/pharmacokinetics , Mice, Nude , Molecular Structure , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacokinetics , Structure-Activity Relationship , Xenograft Model Antitumor AssaysABSTRACT
OBJECTIVE: TGF-beta plays a significant role in vascular injury-induced stenosis. This study evaluates the efficacy of a novel, small molecule inhibitor of ALK5/ALK4 kinase, in the rat carotid injury model of vascular fibrosis. METHODS AND RESULTS: The small molecule, SM16, was shown to bind with high affinity to ALK5 kinase ATP binding site using a competitive binding assay and biacore analysis. SM16 blocked TGF-beta and activin-induced Smad2/3 phosphorylation and TGF-beta-induced plasminogen activator inhibitor (PAI)-luciferase activity in cells. Good overall selectivity was demonstrated in a large panel of kinase assays, but SM16 also showed nanomolar inhibition of ALK4 and weak (micromolar) inhibition of Raf and p38. In the rat carotid injury model, SM16 dosed once daily orally at 15 or 30 mg/kg SM16 for 14 days caused significant inhibition of neointimal thickening and lumenal narrowing. SM16 also prevented induction of adventitial smooth muscle alpha-actin-positive myofibroblasts and the production of intimal collagen, but did not decrease the percentage of proliferative cells. CONCLUSIONS: These results are the first to demonstrate the efficacy of an orally active, small-molecule ALK5/ALK4 inhibitor in a vascular fibrosis model and suggest the potential therapeutic application of these inhibitors in vascular fibrosis.
Subject(s)
Azabicyclo Compounds/pharmacology , Carotid Artery Injuries/drug therapy , Protein Kinase Inhibitors/pharmacology , Protein Serine-Threonine Kinases/antagonists & inhibitors , Receptors, Transforming Growth Factor beta/antagonists & inhibitors , Activin Receptors, Type I/antagonists & inhibitors , Adenosine Triphosphate/metabolism , Administration, Oral , Animals , Azabicyclo Compounds/administration & dosage , Azabicyclo Compounds/metabolism , Binding Sites , Carotid Artery Injuries/pathology , Carotid Artery Injuries/physiopathology , Cell Line , Fibroblasts/drug effects , Fibroblasts/pathology , Fibrosis , Humans , Male , Myoblasts, Smooth Muscle/drug effects , Myoblasts, Smooth Muscle/pathology , Protein Kinase Inhibitors/administration & dosage , Protein Kinase Inhibitors/metabolism , Rats , Rats, Sprague-Dawley , Receptor, Transforming Growth Factor-beta Type I , Transforming Growth Factor beta/physiologyABSTRACT
We describe the discovery, using shape-based virtual screening, of a potent, ATP site-directed inhibitor of the TbetaRI kinase, an important and novel drug target for fibrosis and cancer. The first detailed report of a TbetaRI kinase small molecule co-complex confirms the predicted binding interactions of our small molecule inhibitor, which stabilizes the inactive kinase conformation. Our results validate shape-based screening as a powerful tool to discover useful leads against a new drug target.