ABSTRACT
Fulvestrant is an estrogen receptor (ER) antagonist administered to breast cancer patients by monthly intramuscular injection. Given its present limitations of dosing and route of administration, a more flexible orally available compound has been sought to pursue the potential benefits of this drug in patients with advanced metastatic disease. Here we report the identification and characterization of AZD9496, a nonsteroidal small-molecule inhibitor of ERα, which is a potent and selective antagonist and downregulator of ERα in vitro and in vivo in ER-positive models of breast cancer. Significant tumor growth inhibition was observed as low as 0.5 mg/kg dose in the estrogen-dependent MCF-7 xenograft model, where this effect was accompanied by a dose-dependent decrease in PR protein levels, demonstrating potent antagonist activity. Combining AZD9496 with PI3K pathway and CDK4/6 inhibitors led to further growth-inhibitory effects compared with monotherapy alone. Tumor regressions were also seen in a long-term estrogen-deprived breast model, where significant downregulation of ERα protein was observed. AZD9496 bound and downregulated clinically relevant ESR1 mutants in vitro and inhibited tumor growth in an ESR1-mutant patient-derived xenograft model that included a D538G mutation. Collectively, the pharmacologic evidence showed that AZD9496 is an oral, nonsteroidal, selective estrogen receptor antagonist and downregulator in ER(+) breast cells that could provide meaningful benefit to ER(+) breast cancer patients. AZD9496 is currently being evaluated in a phase I clinical trial. Cancer Res; 76(11); 3307-18. ©2016 AACR.
Subject(s)
Breast Neoplasms/drug therapy , Cinnamates/pharmacology , Estrogen Receptor Modulators/pharmacology , Estrogen Receptor alpha/antagonists & inhibitors , Estrogen Receptor alpha/genetics , Indoles/pharmacology , Mutation/genetics , Administration, Oral , Animals , Apoptosis/drug effects , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Cell Proliferation/drug effects , Cinnamates/administration & dosage , Drug Evaluation, Preclinical , Estrogen Receptor Modulators/administration & dosage , Estrogen Receptor alpha/chemistry , Female , Humans , Indoles/administration & dosage , Mice , Mice, Inbred NOD , Mice, SCID , Protein Conformation , Rats , Tumor Cells, Cultured , Uterus/metabolism , Uterus/pathology , Xenograft Model Antitumor AssaysABSTRACT
The discovery of an orally bioavailable selective estrogen receptor downregulator (SERD) with equivalent potency and preclinical pharmacology to the intramuscular SERD fulvestrant is described. A directed screen identified the 1-aryl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole motif as a novel, druglike ER ligand. Aided by crystal structures of novel ligands bound to an ER construct, medicinal chemistry iterations led to (E)-3-(3,5-difluoro-4-((1R,3R)-2-(2-fluoro-2-methylpropyl)-3-methyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indol-1-yl)phenyl)acrylic acid (30b, AZD9496), a clinical candidate with high oral bioavailability across preclinical species that is currently being evaluated in phase I clinical trials for the treatment of advanced estrogen receptor (ER) positive breast cancer.
Subject(s)
Antineoplastic Agents/metabolism , Cinnamates/chemistry , Cinnamates/metabolism , Estrogen Antagonists/chemical synthesis , Estrogen Antagonists/pharmacology , Estrogen Receptor Modulators/chemical synthesis , Estrogen Receptor Modulators/pharmacology , Indoles/chemistry , Indoles/metabolism , Antineoplastic Agents/chemistry , Breast Neoplasms/drug therapy , Cell Line, Tumor , Cell Proliferation/drug effects , Clinical Trials, Phase I as Topic , Down-Regulation/drug effects , Drug Design , Female , Humans , Injections, Intramuscular , X-Ray DiffractionABSTRACT
Directed screening has identified a novel series of non-zinc binding MMP13 inhibitors that possess good levels of activity whilst demonstrating excellent selectivity over related MMPs. A lead optimisation campaign has delivered compounds with enhanced MMP13 potency, good selectivity and acceptable bioavailability profiles leading to a predicted twice-a-day dosing regimen in man.
Subject(s)
Chemistry, Pharmaceutical/methods , Enzyme Inhibitors/pharmacology , Matrix Metalloproteinase 13/chemistry , Matrix Metalloproteinase Inhibitors , Zinc/chemistry , Animals , Dogs , Drug Design , Humans , Inhibitory Concentration 50 , Models, Chemical , Models, Molecular , Osteoarthritis/drug therapy , Rats , Solubility , Structure-Activity RelationshipABSTRACT
Directed screening has identified a novel series of MMP13 inhibitors that possess good levels of activity whilst possessing excellent selectivity over related MMPs. The binding mode of the series has been solved by co-crystallisation and demonstrates an interesting mode of inhibition without interaction with the catalytic zinc atom.
Subject(s)
Matrix Metalloproteinase Inhibitors , Protease Inhibitors/chemistry , Zinc/chemistry , Binding Sites , Catalytic Domain , Crystallography, X-Ray , Matrix Metalloproteinase 13/metabolism , Protease Inhibitors/chemical synthesis , Protease Inhibitors/pharmacology , Stereoisomerism , Structure-Activity RelationshipABSTRACT
A number of molecular recognition features have been exploited in structure-based design of selective Cathepsin inhibitors.
Subject(s)
Cathepsins/antagonists & inhibitors , Protease Inhibitors/chemistry , Cathepsins/metabolism , Computer Simulation , Crystallography, X-Ray , Drug Design , Protease Inhibitors/chemical synthesis , Protease Inhibitors/pharmacology , Structure-Activity RelationshipABSTRACT
A series of potent Cathepsin L inhibitors with good selectivity with respect to other cysteine Cathepsins is described and SAR is discussed with reference to the crystal structure of a protein-ligand complex.
Subject(s)
Cathepsin L/antagonists & inhibitors , Cathepsin L/chemistry , Nitriles/chemical synthesis , Animals , Cartilage, Articular/pathology , Catalysis , Chemistry, Pharmaceutical/methods , Crystallography, X-Ray/methods , Drug Design , Humans , Ligands , Mice , Mice, Transgenic , Nitriles/chemistry , Nitriles/pharmacology , Peptides/chemical synthesis , Peptides/pharmacology , Proteins/chemistry , Structure-Activity RelationshipABSTRACT
A piperazine series of cyclin-dependent kinase (CDK) inhibitors have been identified. The compounds exhibit excellent physiochemical properties and a novel binding mode, whereby a bridging interaction via a water molecule with Asp 86 of CDK2, leads to selectivity for the CDK family of enzymes over other kinases. Piperazines 2e and 2i were subsequently shown to inhibit tumour growth when dosed orally in a nude mouse xenograft study. Additional chemical series that exploit this unexpected interaction with Asp 86 are also described.
