ABSTRACT
Pyrimidino-thiazolyl carbonitriles were prepared that are potent VEGFR-2 (KDR) kinase inhibitors. The modification of lead structures resulted in 3m which exhibited the best overall profile in KDR inhibitory activity, iv/po pharmacokinetics, and reduced hERG affinity.
Subject(s)
Nitriles/chemical synthesis , Nitriles/pharmacology , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacology , Pyrimidines/chemical synthesis , Pyrimidines/pharmacology , Thiazoles/chemical synthesis , Thiazoles/pharmacology , Vascular Endothelial Growth Factor Receptor-2/antagonists & inhibitors , Animals , Dogs , Macaca mulatta , Molecular Structure , Nitriles/chemistry , Protein Kinase Inhibitors/chemistry , Pyrimidines/chemistry , Rats , Sensitivity and Specificity , Structure-Activity Relationship , Thiazoles/chemistry , Vascular Endothelial Growth Factor Receptor-2/metabolismABSTRACT
Compound I [3-[5-(4-methanesulfonyl-piperazin-1-ylmethyl)-1H-indol-2-yl]-1H-quinolin-2-one] is a potent inhibitor of human kinase insert domain-containing receptor (KDR kinase), which is under investigation for the treatment of cancer. Bile duct-cannulated male beagle dogs were administered 6 mg/kg compound I q.d. for 14 days. There was an approximately 2.5-fold decrease in the mean plasma area under the curve of I on days 7 and 14 (approximately 11.3 microM . h), relative to day 1 (28.2 microM . h). In the dog, compound I was eliminated by metabolism, with a major pathway being aromatic hydroxylation and subsequent sulfation to form the metabolite M3. Metabolic profiling suggested that the pathway leading to the formation of the sulfated conjugate M3 was induced upon multiple dosing of I. Studies conducted in vitro suggested that CYP1A1/2 was responsible for the formation of the hydroxylated metabolite, which is sulfated to yield M3. Additional studies confirmed induction of CYP1A protein and activity in the livers of dogs treated with I. However, studies in a dog hepatocyte model of induction showed a surprising decrease both in CYP1A mRNA and enzymatic activity in the presence of I, emphasizing the need to consider the results from a variety of in vitro and in vivo studies in deriving an understanding of the metabolic fate of a drug candidate. It is concluded that the autoinduction observed after multiple treatments with compound I occurs since compound I is both an inducer and a substrate for dog CYP1A.
Subject(s)
Cytochrome P-450 CYP1A1/biosynthesis , Protein Kinase Inhibitors/pharmacology , Animals , Base Sequence , Chromatography, High Pressure Liquid , Cytochrome P-450 CYP1A1/antagonists & inhibitors , Cytochrome P-450 CYP1A1/genetics , DNA Primers , Dogs , Enzyme Induction , Hepatocytes/drug effects , Hepatocytes/enzymology , In Vitro Techniques , Male , Mass Spectrometry , Protein Kinase Inhibitors/pharmacokineticsABSTRACT
A strategy for antagonizing vascular endothelial growth factor (VEGF) -induced angiogenesis is to inhibit the kinase activity of its receptor, kinase insert domain-containing receptor (KDR), the first committed and perhaps the last unique step in the VEGF signaling cascade. We synthesized a novel ATP-competitive KDR tyrosine kinase inhibitor that potently suppresses human and mouse KDR activity in enzyme (IC(50) = 7.8-19.5 nM) and cell-based assays (IC(50) = 8 nM). The compound was bioavailable in vivo, leading to a dose-dependent decrease in basal- and VEGF-stimulated KDR tyrosine phosphorylation in lungs from naïve and tumor-bearing mice (IC(50) = 23 nM). Pharmacokinetics and pharmacodynamics guided drug dose selection for antitumor efficacy studies. HT1080 nude mice xenografts were treated orally twice daily with vehicle, or 33 or 133 mg/kg of compound. These doses afforded trough plasma concentrations approximately equal to the IC(50) for inhibition of KDR autophosphorylation in vivo for the 33 mg/kg group, and higher than the IC(99) for the 133 mg/kg group. Chronic treatment at these doses was well-tolerated and resulted in dose-dependent inhibition of tumor growth, decreased tumor vascularization, decreased proliferation, and enhanced cell death. Antitumor efficacy correlated with inhibition of KDR tyrosine phosphorylation in the tumor, as well as in a surrogate tissue (lung). Pharmacokinetics and pharmacodynamics assessment indicated that the degree of tumor growth inhibition correlated directly with the extent of inhibition of KDR tyrosine phosphorylation in tumor or lung at trough. These observations highlight the need to design antiangiogenic drug regimens to ensure constant target suppression and to take advantage of PD end points to guide dose selection.
Subject(s)
Angiogenesis Inhibitors/therapeutic use , Antineoplastic Agents/pharmacokinetics , Antineoplastic Agents/therapeutic use , Enzyme Inhibitors/pharmacokinetics , Enzyme Inhibitors/therapeutic use , Fibrosarcoma/drug therapy , Vascular Endothelial Growth Factor Receptor-2/antagonists & inhibitors , Administration, Oral , Angiogenesis Inhibitors/administration & dosage , Angiogenesis Inhibitors/pharmacokinetics , Animals , Antineoplastic Agents/administration & dosage , Biological Availability , Cell Division/drug effects , Cell Line, Tumor , Enzyme Inhibitors/administration & dosage , Fibrosarcoma/pathology , Humans , Mice , Mice, Nude , Phosphorylation , Transplantation, Heterologous , Vascular Endothelial Growth Factor A/antagonists & inhibitors , Vascular Endothelial Growth Factor Receptor-2/metabolismABSTRACT
Modifications to the basic side-chain of early lead structures of the indolyl quinolinone class of KDR kinase inhibitors resulted in improved pharmacokinetic and ancillary profiles. Specifically, compounds bearing 5-amido- and 5-sulphonamido-indolyl substituents exhibited lower plasma clearance and weaker binding affinity for the I(Kr) potassium channel hERG.
Subject(s)
Cation Transport Proteins/metabolism , Enzyme Inhibitors/pharmacokinetics , Potassium Channels, Voltage-Gated , Potassium Channels/metabolism , Quinolones/pharmacokinetics , Vascular Endothelial Growth Factor Receptor-2/antagonists & inhibitors , Animals , Cell Line , Dogs , Enzyme Inhibitors/chemistry , Ether-A-Go-Go Potassium Channels , Humans , Microsomes, Liver/enzymology , Protein Binding/physiology , Quinolones/chemistry , Rats , Vascular Endothelial Growth Factor Receptor-2/metabolismABSTRACT
1,5-Diarylbenzimidazoles have been identified as potent inhibitors of KDR kinase activity. The series was developed with a goal of finding compounds with optimal drug-like properties. This communication describes structural modifications in the series that enhance solubility, lower protein binding, and provide compounds with excellent potency and pharmacokinetic profiles.