ABSTRACT
The discovery of potent, kinome selective, brain penetrant LRRK2 inhibitors is the focus of extensive research seeking new, disease-modifying treatments for Parkinson's disease (PD). Herein, we describe the discovery and evolution of a picolinamide-derived lead series. Our initial optimization efforts aimed at improving the potency and CLK2 off-target selectivity of compound 1 by modifying the heteroaryl C-H hinge and linker regions. This resulted in compound 12 which advanced deep into our research operating plan (ROP) before heteroaryl aniline metabolite 14 was characterized as Ames mutagenic, halting its progression. Strategic modifications to our ROP were made to enable early de-risking of putative aniline metabolites or hydrolysis products for mutagenicity in Ames. This led to the discovery of 3,5-diaminopyridine 15 and 4,6-diaminopyrimidine 16 as low risk for mutagenicity (defined by a 3-strain Ames negative result). Analysis of key matched molecular pairs 17 and 18 led to the prioritization of the 3,5-diaminopyridine sub-series for further optimization due to enhanced rodent brain penetration. These efforts culminated in the discovery of ethyl trifluoromethyl pyrazole 23 with excellent LRRK2 potency and expanded selectivity versus off-target CLK2.
ABSTRACT
The initial structure activity relationships around an isoindoline uHTS hit will be described. Information gleaned from ligand co-crystal structures allowed for rapid refinements in both MARK potency and kinase selectivity. These efforts allowed for the identification of a compound with properties suitable for use as an in vitro tool compound for validation studies on MARK as a viable target for Alzheimer's disease.
Subject(s)
Drug Design , Protein Kinase Inhibitors/pharmacology , Pyrimidinones/pharmacology , Pyrroles/pharmacology , Alzheimer Disease/drug therapy , Alzheimer Disease/metabolism , Cell Line , Crystallography, X-Ray , Dose-Response Relationship, Drug , Humans , Models, Molecular , Molecular Structure , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/chemistry , Protein Serine-Threonine Kinases/antagonists & inhibitors , Protein Serine-Threonine Kinases/metabolism , Pyrimidinones/chemical synthesis , Pyrimidinones/chemistry , Pyrroles/chemical synthesis , Pyrroles/chemistry , Structure-Activity RelationshipABSTRACT
Attempts to optimize pharmacokinetic properties in a promising series of pyrrolopyrimidinone MARK inhibitors for the treatment of Alzheimer's disease are described. A focus on physical properties and ligand efficiency while prosecuting this series afforded key tool compounds that revealed a large discrepancy in the rat in vitro-in vivo DMPK (Drug Metabolism/Pharmacokinetics) correlation. These differences prompted an in vivo rat disposition study employing a radiolabeled representative of the series, and the results from this experiment justified the termination of any further optimization efforts.
Subject(s)
Alzheimer Disease/drug therapy , Protein Kinase Inhibitors/pharmacology , Pyrimidinones/pharmacology , Pyrroles/pharmacology , Alzheimer Disease/metabolism , Animals , Dose-Response Relationship, Drug , Humans , Isoenzymes/antagonists & inhibitors , Isoenzymes/metabolism , Molecular Structure , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/metabolism , Protein Serine-Threonine Kinases/antagonists & inhibitors , Protein Serine-Threonine Kinases/metabolism , Pyrimidinones/chemistry , Pyrimidinones/metabolism , Pyrroles/chemistry , Pyrroles/metabolism , Rats , Structure-Activity RelationshipABSTRACT
A series of carboxamide-substituted thiophenes demonstrating inhibition of JAK2 is described. Development of this chemical series began with the bioisosteric replacement of a urea substituent by a pyridyl ring. Issues of chemical and metabolic stability were solved using the results of both in vitro and in vivo studies, ultimately delivering compounds such as 24 and 25 that performed well in an acute PK/PD model measuring p-STAT5 inhibition.
