ABSTRACT
Herein we describe the discovery of a novel series of ATP competitive B-Raf inhibitors via structure based drug design (SBDD). These pyridopyrimidin-7-one based inhibitors exhibit both excellent cellular potency and striking B-Raf selectivity. Optimization led to the identification of compound 17, a potent, selective and orally available agent with excellent pharmacokinetic properties and robust tumor growth inhibition in xenograft studies.
Subject(s)
Drug Discovery , Protein Kinase Inhibitors/pharmacology , Proto-Oncogene Proteins B-raf/antagonists & inhibitors , Pyrimidinones/pharmacology , Administration, Oral , Biological Availability , Crystallography, X-Ray , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacokinetics , Pyrimidinones/chemistry , Pyrimidinones/pharmacokineticsABSTRACT
Recent clinical data provided proof-of-concept for selective B-Raf inhibitors in treatment of B-Raf(V600E) mutant melanoma. Pyrazolopyridine-type B-Raf inhibitors previously described by the authors are potent and selective but exhibit low solubility requiring the use of amorphous dispersion-based formulation for achieving efficacious drug exposures. Through structure-based design, we discovered a new class of highly potent aminopyrimidine-based B-Raf inhibitors with improved solubility and pharmacokinetic profiles. The hinge binding moiety possesses a basic center imparting high solubility at gastric pH, addressing the dissolution limitation observed with our previous series. In our search for an optimal linker-hinge binding moiety system, amide-linked thieno[3,2-d]pyrimidine analogues 32 and 35 (G945), molecules with desirable physicochemical properties, emerged as lead compounds with strong efficacy in a B-Raf(V600E) mutant mouse xenograft model. Synthesis, SAR, lead selection, and evaluation of key compounds in animal studies will be described.
Subject(s)
Aminopyridines/chemical synthesis , Antineoplastic Agents/chemical synthesis , Proto-Oncogene Proteins B-raf/antagonists & inhibitors , Aminopyridines/pharmacokinetics , Aminopyridines/pharmacology , Animals , Antineoplastic Agents/pharmacokinetics , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Crystallography, X-Ray , Drug Screening Assays, Antitumor , Mice , Models, Molecular , Molecular Structure , Neoplasm Transplantation , Quinazolines/chemical synthesis , Quinazolines/pharmacokinetics , Quinazolines/pharmacology , Rats , Solubility , Structure-Activity Relationship , Thiophenes/chemical synthesis , Thiophenes/pharmacokinetics , Thiophenes/pharmacology , Transplantation, HeterologousABSTRACT
Herein we describe a novel series of ATP competitive B-Raf inhibitors based on the pyrazolo[1,5-a]pyrimidine scaffold. These inhibitors exhibit both excellent cellular potency and striking B-Raf selectivity. Optimization led to the identification of compound 17, a potent, selective and orally available agent with improved physicochemical and pharmacokinetic properties.
Subject(s)
Enzyme Inhibitors/pharmacology , Proto-Oncogene Proteins B-raf/antagonists & inhibitors , Pyrazoles/pharmacology , Pyrimidines/pharmacology , Animals , Chemistry, Physical , Crystallography, X-Ray , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Mice , Models, Molecular , Molecular Structure , Proto-Oncogene Proteins B-raf/metabolism , Pyrazoles/chemical synthesis , Pyrazoles/chemistry , Pyrimidines/chemical synthesis , Pyrimidines/chemistry , Stereoisomerism , Structure-Activity RelationshipABSTRACT
Structure-activity relationships around a novel series of B-Raf(V600E) inhibitors are reported. The enzymatic and cellular potencies of inhibitors derived from two related hinge-binding groups were compared and3-methoxypyrazolopyridine proved to be superior. The 3-alkoxy group of lead B-Raf(V600E) inhibitor 1 was extended and minimally affected potency. The propyl sulfonamide tail of compound 1, which occupies the small lipophilic pocket formed by an outward shift of the αC-helix, was expanded to a series of arylsulfonamides. X-ray crystallography revealed that this lipophilic pocket unexpectedly enlarges to accommodate the bulkier aryl group.
Subject(s)
Protein Kinase Inhibitors/pharmacology , Proto-Oncogene Proteins B-raf/antagonists & inhibitors , Pyrazoles/pharmacology , Pyridines/pharmacology , Crystallography, X-Ray , Dose-Response Relationship, Drug , Models, Molecular , Molecular Structure , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/chemistry , Proto-Oncogene Proteins B-raf/metabolism , Pyrazoles/chemical synthesis , Pyrazoles/chemistry , Pyridines/chemical synthesis , Pyridines/chemistry , Stereoisomerism , Structure-Activity RelationshipABSTRACT
The development of inhibitors of B-Raf(V600E) serine-threonine kinase is described. Various head-groups were examined to optimize inhibitor activity and ADME properties. Several of the head-groups explored, including naphthol, phenol and hydroxyamidine, possessed good activity but had poor pharmacokinetic exposure in mice. Exposure was improved by incorporating more metabolically stable groups such as indazole and tricyclic pyrazole, while indazole could also be optimized for good cellular activity.
Subject(s)
Protein Kinase Inhibitors/chemistry , Proto-Oncogene Proteins B-raf/antagonists & inhibitors , Amino Acid Substitution , Animals , Binding Sites , Cell Line, Tumor , Crystallography, X-Ray , Humans , Indazoles/chemistry , Mice , Microsomes, Liver/metabolism , Mutation , Oximes/chemistry , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacokinetics , Proto-Oncogene Proteins B-raf/genetics , Proto-Oncogene Proteins B-raf/metabolism , Pyrazoles/chemistry , Structure-Activity RelationshipABSTRACT
Virtual and high-throughput screening identified imidazo[1,2-a]pyrazines as inhibitors of B-Raf. We describe the rationale, SAR, and evolution of the initial hits to a series of furo[2,3-c]pyridine indanone oximes as highly potent and selective inhibitors of B-Raf.
Subject(s)
Indans/chemistry , Oximes/chemistry , Protein Kinase Inhibitors/chemistry , Proto-Oncogene Proteins B-raf/antagonists & inhibitors , Pyridines/chemistry , Animals , Binding Sites , Cell Line, Tumor , Computer Simulation , Drug Evaluation, Preclinical , Humans , Indans/chemical synthesis , Indans/pharmacokinetics , Microsomes, Liver/metabolism , Models, Chemical , Models, Molecular , Oximes/chemical synthesis , Oximes/pharmacokinetics , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacokinetics , Proto-Oncogene Proteins B-raf/metabolism , Rats , Structure-Activity RelationshipABSTRACT
The V600E mutation of B-Raf kinase results in constitutive activation of the MAPK signaling pathway and is present in approximately 7% of all cancers. Using structure-based design, a novel series of pyrazolopyridine inhibitors of B-Raf(V600E) was developed. Optimization led to the identification of 3-methoxy pyrazolopyridines 17 and 19, potent, selective, and orally bioavailable agents that inhibited tumor growth in a mouse xenograft model driven by B-Raf(V600E) with no effect on body weight. On the basis of their in vivo efficacy and preliminary safety profiles, 17 and 19 were selected for further preclinical evaluation.
