ABSTRACT
Targeting the estrogen receptor alpha (ERα) pathway is validated in the clinic as an effective means to treat ER+ breast cancers. Here we present the development of a VHL-targeting and orally bioavailable proteolysis-targeting chimera (PROTAC) degrader of ERα. In vitro studies with this PROTAC demonstrate excellent ERα degradation and ER antagonism in ER+ breast cancer cell lines. However, upon dosing the compound in vivo we observe an in vitro-in vivo disconnect. ERα degradation is lower in vivo than expected based on the in vitro data. Investigation into potential causes for the reduced maximal degradation reveals that metabolic instability of the PROTAC linker generates metabolites that compete for binding to ERα with the full PROTAC, limiting degradation. This observation highlights the requirement for metabolically stable PROTACs to ensure maximal efficacy and thus optimisation of the linker should be a key consideration when designing PROTACs.
Subject(s)
Estrogen Receptor alpha , Proteolysis , Von Hippel-Lindau Tumor Suppressor Protein , Humans , Estrogen Receptor alpha/metabolism , Von Hippel-Lindau Tumor Suppressor Protein/metabolism , Von Hippel-Lindau Tumor Suppressor Protein/genetics , Female , Proteolysis/drug effects , Animals , Administration, Oral , Breast Neoplasms/drug therapy , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Cell Line, Tumor , Mice , Antineoplastic Agents/pharmacology , Antineoplastic Agents/administration & dosageABSTRACT
In this article, we report the discovery of a series of pyrimidopyridones as inhibitors of IRAK4 kinase. From a previously disclosed 5-azaquinazoline series, we found that switching the pyridine ring for an N-substituted pyridone gave a novel hinge binding scaffold which retained potency against IRAK4. Importantly, introduction of the carbonyl established an internal hydrogen bond with the 4-NH, establishing a conformational lock and allowing truncation of the large basic substituent to a 1-methylcyclopyl group. Subsequent optimisation, facilitated by X-ray crystal structures, allowed identification of preferred substituents at both the pyridone core and pyrazole. Subsequent combinations of optimal groups allowed control of lipophilicity and identification of potent and selective inhibitors of IRAK4 with better in vitro permeability and lower clearance.
Subject(s)
Interleukin-1 Receptor-Associated Kinases , Pyridones , Molecular Conformation , Pyridones/pharmacology , Structure-Activity RelationshipABSTRACT
In this article, we report our efforts towards improving in vitro human clearance in a series of 5-azaquinazolines through a series of C4 truncations and C2 expansions. Extensive DMPK studies enabled us to tackle high Aldehyde Oxidase (AO) metabolism and unexpected discrepancies in human hepatocyte and liver microsomal intrinsic clearance. Our efforts culminated with the discovery of 5-azaquinazoline 35, which also displayed exquisite selectivity for IRAK4, and showed synergistic in vitro activity against MyD88/CD79 double mutant ABC-DLBCL in combination with the covalent BTK inhibitor acalabrutinib.
Subject(s)
Interleukin-1 Receptor-Associated Kinases/antagonists & inhibitors , Protein Kinase Inhibitors/metabolism , Quinazolines/chemistry , Aldehyde Oxidase/metabolism , Animals , Binding Sites , Cell Line, Tumor , Cell Survival/drug effects , Crystallography, X-Ray , Dogs , Drug Stability , Half-Life , Hepatocytes/metabolism , Humans , Interleukin-1 Receptor-Associated Kinases/metabolism , Mice , Microsomes, Liver/metabolism , Molecular Dynamics Simulation , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Quinazolines/metabolism , Quinazolines/pharmacology , Rats , Structure-Activity RelationshipABSTRACT
A palladium-catalysed Buchwald-Hartwig amination for lenalidomide-derived aryl bromides was optimised using high throughput experimentation (HTE). The substrate scope of the optimised conditions was evaluated for a range of alkyl- and aryl- amines and functionalised aryl bromides. The methodology allows access to new cereblon-based bifunctional proteolysis targeting chimeras with a reduced step count and improved yields.
Subject(s)
Amines/chemistry , Bromides/chemistry , Lenalidomide/chemistry , Proteolysis/drug effects , Amination , Ligands , Ubiquitin-Protein Ligases/metabolismABSTRACT
Highly functionalized aldol-type products bearing a ß-quaternary center and a stereoselectively controlled γ-hydroxy function are readily prepared by the diastereoselective addition of an allylic zinc reagent embedded in an isoxazole ring to various aromatic and heteroaromatic aldehydes, in the presence of Lewis acids, such as MgCl2 or LaCl3â 2 LiCl. After reductive cleavage of the N-O bond by using Fe, NH4Cl, aldol-type products bearing a stereocontrolled ß-quaternary center and a γ-hydroxy group were observed. The benzylic reactivity of the isoxazolylmethylzinc reagent towards other electrophiles, such as acid chlorides, aryl and allylic halides, as well as aldehydes in the presence of BF3â OEt2 are also described.
Subject(s)
Aldehydes/chemistry , Isoxazoles/chemistry , Zinc/chemistry , Indicators and Reagents , Lewis Acids/chemistry , Models, Molecular , Organometallic Compounds/chemistry , StereoisomerismABSTRACT
A new Fe- or Co-catalyzed Cl/Zn-exchange reaction allows the direct transformation of aryl, heteroaryl, and also alkyl chlorides into the corresponding zinc reagents. The method tolerates functional groups such as a nitrile or an ester. Remarkably, secondary and tertiary alkyl chlorides are suitable substrates for the Cl/Zn exchange.
