Kevin P. Quinn

Design of an orally efficacious hydroxyethylamine (HEA) BACE-1 inhibitor in a preclinical animal model.

In this Letter, we describe our efforts to design HEA BACE-1 inhibitors that are highly permeable coupled with negligible levels of permeability-glycoprotein activity. These efforts culminate in producing 16 which lowers Αβ by 28% and 32% in the cortex and CSF, respectively, in the preclinical wild type Hartley guinea pig animal model when dosed orally at 30mpk BID for 2.5days.

Design, synthesis, and structure–activity relationship of novel orally efficacious pyrazole/sulfonamide based dihydroquinoline γ-secretase inhibitors

In this Letter, we report our strategy to design potent and metabolically stable gamma-secretase inhibitors that are efficacious in reducing the cortical Abetax-40 levels in FVB mice via a single PO dose.

Highly selective c-Jun N-terminal kinase (JNK) 2 and 3 inhibitors with in vitro CNS-like pharmacokinetic properties prevent neurodegeneration.

In this Letter, we describe the discovery of selective JNK2 and JNK3 inhibitors, such as 10, that routinely exhibit >10-fold selectivity over JNK1 and >1000-fold selectivity over related MAPKs, p38α and ERK2. Substitution of the naphthalene ring affords an isoform selective JNK3 inhibitor, 30, with approximately 10-fold selectivity over both JNK1 and JNK2. A naphthalene ring penetrates deep into the selectivity pocket accounting for the differentiation amongst the kinases. Interestingly, the gatekeeper Met146 sulfide interacts with the naphthalene ring in a sulfur-π stacking interaction. Compound 38 ameliorates neurotoxicity induced by amyloid-β in human cortical neurons. Lastly, we demonstrate how to install propitious in vitro CNS-like properties into these selective inhibitors.

Design and synthesis of a novel, orally active, brain penetrant, tri-substituted thiophene based JNK inhibitor.

The SAR of a series of tri-substituted thiophene JNK3 inhibitors is described. By optimizing both the N-aryl acetamide region of the inhibitor and the 4-position of the thiophene we obtained single digit nanomolar compounds, such as 47, which demonstrated an in vivo effect on JNK activity when dosed orally in our kainic acid mouse model as measured by phospho-c-jun reduction.

Novel cinnoline-based inhibitors of LRRK2 kinase activity.

Leucine rich repeat kinase 2 (LRRK2) has been implicated in the pathogenesis of Parkinsons disease (PD). Inhibition of LRRK2 kinase activity is a therapeutic approach that may lead to new treatments for PD. Herein we report the discovery of a series of cinnoline-3-carboxamides that are potent against both wild-type and mutant LRRK2 kinase activity in biochemical assays. These compounds are also shown to be potent inhibitors in a cellular assay and to have good to excellent CNS penetration.

Design and synthesis of brain penetrant selective JNK inhibitors with improved pharmacokinetic properties for the prevention of neurodegeneration.

The SAR of a series of brain penetrant, trisubstituted thiophene based JNK inhibitors with improved pharmacokinetic properties is described. These compounds were designed based on information derived from metabolite identification studies which led to compounds such as 42 with lower clearance, greater brain exposure and longer half life compared to earlier analogs.

Discovery of 4-alkylamino-7-aryl-3-cyanoquinoline LRRK2 kinase inhibitors

Mutations in leucine-rich repeat kinase 2 (LRRK2) are associated with familial Parkinsons disease (PD). The kinase activity of this complex protein is increased by pathogenic mutations. Inhibition of LRRK2 kinase activity has therefore emerged as a promising approach for the treatment of PD. Herein we report our findings on a series of 4-alkylamino-7-aryl-3-cyanoquinolines that exhibit kinase inhibitory activity against both wild type and G2019S mutant LRRK2. Activity was determined in both biochemical and cellular assays. Compound 14 was further evaluated in an in vivo pharmacodynamic study and found to significantly inhibit Ser935 phosphorylation after oral dosing.

Triazolopyridazine LRRK2 kinase inhibitors

Leucine-rich repeat kinase 2 (LRRK2) has been implicated in the pathogenesis of Parkinsons disease (PD). Inhibition of LRRK2 kinase activity is a therapeutic approach that may lead to new treatments for PD. Herein we report the discovery of a series of [1,2,4]triazolo[4,3-b]pyridazines that are potent against both wild-type and mutant LRRK2 kinase activity in biochemical assays and show an unprecedented selectivity towards the G2019S mutant. A structural rational for the observed selectivity is proposed.

Design and synthesis of disubstituted thiophene and thiazole based inhibitors of JNK.

From high throughput screening, we discovered compound 1, the prototype for a series of disubstituted thiophene inhibitors of JNK which is selective towards closely related MAP kinases p38 and Erk2. Herein we describe the evolution of these compounds to a novel class of thiophene and thiazole JNK inhibitors that retain favorable solubility, permeability, and P-gp properties for development as CNS agents for treatment of neurodegeneration. Compound 61 demonstrated JNK3 IC(50)=77 nM and retained the excellent broad kinase selectivity observed for the series.

Design and synthesis of hydroxyethylamine (HEA) BACE-1 inhibitors: structure-activity relationship of the aryl region.

The structure-activity relationship of the prime region of hydroxyethylamine BACE inhibitors is described. Variation in the aryl linker region with 5- and 6-membered heterocycles provided compounds such as 33 with improved permeability and reduced P-gp liability compared to benzyl amine analog 1.