ABSTRACT
Starting from the micromolar 8-quinoline carboxamide high-throughput screening hit 1a, a systematic exploration of the structure-activity relationships (SAR) of the 4-, 6-, and 8-substituents of the quinoline ring resulted in the identification of approximately 10-100-fold more potent human CD38 inhibitors. Several of these molecules also exhibited pharmacokinetic parameters suitable for in vivo animal studies, including low clearances and decent oral bioavailability. Two of these CD38 inhibitors, 1ah and 1ai, were shown to elevate NAD tissue levels in liver and muscle in a diet-induced obese (DIO) C57BL/6 mouse model. These inhibitor tool compounds will enable further biological studies of the CD38 enzyme as well as the investigation of the therapeutic implications of NAD enhancement in disease models of abnormally low NAD.
Subject(s)
ADP-ribosyl Cyclase 1/antagonists & inhibitors , Amides/chemistry , Aminoquinolines/chemistry , NAD/metabolism , Quinolines/chemistry , Amides/chemical synthesis , Amides/pharmacology , Aminoquinolines/chemical synthesis , Aminoquinolines/pharmacology , Animals , Biological Availability , Crystallography, X-Ray , Humans , Hydrolysis , Liver/metabolism , Membranes, Artificial , Mice, Inbred C57BL , Models, Molecular , Muscle, Skeletal/metabolism , Obesity/metabolism , Permeability , Protein Conformation , Quinolines/chemical synthesis , Quinolines/pharmacology , Stereoisomerism , Structure-Activity RelationshipABSTRACT
Mitogen-Activated Protein Kinase (MAPK) pathway activation has been implicated in many types of human cancer. BRAF mutations that constitutively activate MAPK signalling and bypass the need for upstream stimuli occur with high prevalence in melanoma, colorectal carcinoma, ovarian cancer, papillary thyroid carcinoma, and cholangiocarcinoma. In this report we characterize the novel, potent, and selective BRAF inhibitor, dabrafenib (GSK2118436). Cellular inhibition of BRAF(V600E) kinase activity by dabrafenib resulted in decreased MEK and ERK phosphorylation and inhibition of cell proliferation through an initial G1 cell cycle arrest, followed by cell death. In a BRAF(V600E)-containing xenograft model of human melanoma, orally administered dabrafenib inhibited ERK activation, downregulated Ki67, and upregulated p27, leading to tumor growth inhibition. However, as reported for other BRAF inhibitors, dabrafenib also induced MAPK pathway activation in wild-type BRAF cells through CRAF (RAF1) signalling, potentially explaining the squamous cell carcinomas and keratoacanthomas arising in patients treated with BRAF inhibitors. In addressing this issue, we showed that concomitant administration of BRAF and MEK inhibitors abrogated paradoxical BRAF inhibitor-induced MAPK signalling in cells, reduced the occurrence of skin lesions in rats, and enhanced the inhibition of human tumor xenograft growth in mouse models. Taken together, our findings offer preclinical proof of concept for dabrafenib as a specific and highly efficacious BRAF inhibitor and provide evidence for its potential clinical benefits when used in combination with a MEK inhibitor.
Subject(s)
Melanoma/drug therapy , Melanoma/metabolism , Mitogen-Activated Protein Kinases/metabolism , Proto-Oncogene Proteins B-raf/metabolism , Animals , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Cell Line, Tumor , Drug Evaluation, Preclinical , Enzyme Activation/drug effects , Female , Humans , Imidazoles/administration & dosage , Melanoma/pathology , Mice , Mitogen-Activated Protein Kinases/antagonists & inhibitors , Mutation , Oximes/administration & dosage , Proto-Oncogene Proteins B-raf/antagonists & inhibitors , Proto-Oncogene Proteins B-raf/genetics , Pyridones/administration & dosage , Pyrimidinones/administration & dosage , Signal Transduction/drug effects , Tumor Burden/drug effects , Xenograft Model Antitumor AssaysABSTRACT
Hyperactive signaling of the MAP kinase pathway resulting from the constitutively active B-Raf(V600E) mutated enzyme has been observed in a number of human tumors, including melanomas. Herein we report the discovery and biological evaluation of GSK2118436, a selective inhibitor of Raf kinases with potent in vitro activity in oncogenic B-Raf-driven melanoma and colorectal carcinoma cells and robust in vivo antitumor and pharmacodynamic activity in mouse models of B-Raf(V600E) human melanoma. GSK2118436 was identified as a development candidate, and early clinical results have shown significant activity in patients with B-Raf mutant melanoma.
ABSTRACT
A potent series of inhibitors against the B-Raf(V600E) kinase have been developed that show excellent activity in cellular assays and good oral bioavailability in rats. The key structural features of the series are an arylsulfonamide headgroup, a thiazole core, and a fluorine ortho to the sulfonamide nitrogen.
Subject(s)
Protein Kinase Inhibitors/chemistry , Proto-Oncogene Proteins B-raf/antagonists & inhibitors , Sulfonamides/chemistry , Administration, Oral , Amino Acid Substitution , Animals , Binding Sites , Catalytic Domain , Fluorine/chemistry , Microsomes, Liver/metabolism , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacokinetics , Proto-Oncogene Proteins B-raf/genetics , Proto-Oncogene Proteins B-raf/metabolism , Rats , Structure-Activity RelationshipABSTRACT
Potent inhibitors of PLK1 with acceptable solubility, mouse iv clearance, and reduced CYP450 inhibition were identified. Drug-like properties were improved using a heteroaryl ring as a functional handle for manipulation of inhibitors' physiochemical and DMPK properties.
Subject(s)
Amides/chemistry , Antineoplastic Agents/chemistry , Cell Cycle Proteins/antagonists & inhibitors , Protein Kinase Inhibitors/chemistry , Protein Serine-Threonine Kinases/antagonists & inhibitors , Proto-Oncogene Proteins/antagonists & inhibitors , Amides/chemical synthesis , Amides/pharmacology , Animals , Antineoplastic Agents/chemical synthesis , Antineoplastic Agents/pharmacology , Binding Sites , Cell Cycle Proteins/metabolism , Cell Line, Tumor , Computer Simulation , Cytochrome P-450 Enzyme Inhibitors , Cytochrome P-450 Enzyme System/metabolism , Humans , Injections, Intravenous , Mice , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacology , Protein Serine-Threonine Kinases/metabolism , Proto-Oncogene Proteins/metabolism , Structure-Activity Relationship , Thiophenes/chemistry , Polo-Like Kinase 1ABSTRACT
Two new series of potent and selective dual EGFR/ErbB-2 kinase inhibitors derived from novel thienopyrimidine cores have been identified. Isomeric thienopyrimidine cores were evaluated as isosteres for a 4-anilinoquinazoline core and several analogs containing the thieno[3,2-d]pyrimidine core showed anti-proliferative activity with IC(50) values less than 1 microM against human tumor cells in vitro.
Subject(s)
Antineoplastic Agents/pharmacology , Chemistry, Pharmaceutical/methods , ErbB Receptors/chemistry , Pyrimidines/chemistry , Receptor, ErbB-2/antagonists & inhibitors , Antineoplastic Agents/chemical synthesis , Cell Line, Tumor , Cell Proliferation , Drug Design , Drug Screening Assays, Antitumor , Enzyme Inhibitors/pharmacology , Humans , Inhibitory Concentration 50 , Lapatinib , Models, Chemical , Molecular Conformation , Quinazolines/pharmacologyABSTRACT
A novel class of pyrrolidinyl-acetyleneic thieno[3,2-d]pyrimidines has been identified which potently inhibit the EGFR and ErbB-2 receptor tyrosine kinases. Synthetic modifications of the pyrrolidine carbamate moiety result in a range of effects on enzyme and cellular potency. In addition, the impact of the absolute stereochemical configuration on cellular potency and oral mouse pharmacokinetics is described.
Subject(s)
Antineoplastic Agents/chemistry , ErbB Receptors/antagonists & inhibitors , Pyrimidines/pharmacology , Pyrrolidines/pharmacology , Receptor, ErbB-2/antagonists & inhibitors , Administration, Oral , Animals , Mice , Pharmacokinetics , Pyrimidines/chemical synthesis , Pyrrolidines/chemical synthesis , Structure-Activity RelationshipABSTRACT
The stereochemical preference (syn or anti) when prochiral radicals add to prochiral acceptors is of fundamental interest. The primary focus of this research was to determine which factors influence the relative stereochemistry between the beta and gamma chiral centers when these are formed concurrently. While moderate diastereoselectivity was found for addition of alkyl (6a-d) and alpha-alkoxy radicals (16a-c) (< or =6:1 syn) to acceptors 4, 7, 8, 10, and 14, consistently high selectivity was observed with less reactive halogenated radicals (6f,g) (>15:1 anti). Steric influence in alkyl radical additions was difficult to evaluate due to decreased reactivity when using bulky reaction partners; however, more reactive alpha-alkoxy radicals, it was found that increasing steric bulk leads to moderate increases in selectivity. In addition, higher selectivity was observed when employing lanthanide Lewis acids whose environment (reactivity) was modified using achiral additives, suggesting a potentially simple means for selectivity enhancements in radical reactions. Overall these results indicate that significant stereoelectronic effects are necessary to achieve high levels of selectivity in prochiral radical additions to prochiral acceptors.
