ABSTRACT
Polo-like kinase-2 (Plk-2) has been implicated as the dominant kinase involved in the phosphorylation of α-synuclein in Lewy bodies, which are one of the hallmarks of Parkinson's disease neuropathology. Potent, selective, brain-penetrant inhibitors of Plk-2 were obtained from a structure-guided drug discovery approach driven by the first reported Plk-2-inhibitor complexes. The best of these compounds showed excellent isoform and kinome-wide selectivity, with physicochemical properties sufficient to interrogate the role of Plk-2 inhibition inâ vivo. One such compound significantly decreased phosphorylation of α-synuclein in rat brain upon oral administration and represents a useful probe for future studies of this therapeutic avenue toward the potential treatment of Parkinson's disease.
Subject(s)
Brain/metabolism , Protein Kinase Inhibitors/chemistry , Protein Serine-Threonine Kinases/antagonists & inhibitors , alpha-Synuclein/metabolism , Animals , Binding Sites , Blood-Brain Barrier/metabolism , Female , HEK293 Cells , Half-Life , Humans , Male , Mice , Molecular Dynamics Simulation , Phosphorylation/drug effects , Protein Isoforms/antagonists & inhibitors , Protein Isoforms/metabolism , Protein Kinase Inhibitors/chemical synthesis , Protein Kinase Inhibitors/pharmacokinetics , Protein Serine-Threonine Kinases/metabolism , Protein Structure, Tertiary , Rats , Rats, Sprague-DawleyABSTRACT
Herein, we describe our strategy to design metabolically stable γ-secretase inhibitors which are selective for inhibition of Aß generation over Notch. We highlight our synthetic strategy to incorporate diversity and chirality. Compounds 30 (ELND006) and 34 (ELND007) both entered human clinical trials. The in vitro and in vivo characteristics for these two compounds are described. A comparison of inhibition of Aß generation in vivo between 30, 34, Semagacestat 41, Begacestat 42, and Avagacestat 43 in mice is made. 30 lowered Aß in the CSF of healthy human volunteers.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Amyloid beta-Peptides/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Heterocyclic Compounds, 3-Ring/pharmacology , Pyrazoles/pharmacology , Quinolines/pharmacology , Receptors, Notch/antagonists & inhibitors , Sulfonamides/pharmacology , Amyloid Precursor Protein Secretases/metabolism , Amyloid beta-Peptides/cerebrospinal fluid , Amyloid beta-Peptides/metabolism , Animals , Area Under Curve , Basic Helix-Loop-Helix Transcription Factors/genetics , Dogs , Dose-Response Relationship, Drug , Drug Design , Drug Stability , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacokinetics , Gene Expression/drug effects , Heterocyclic Compounds, 3-Ring/chemistry , Homeodomain Proteins/genetics , Humans , Male , Mice , Microsomes, Liver/drug effects , Microsomes, Liver/metabolism , Models, Chemical , Molecular Structure , Pyrazoles/chemical synthesis , Pyrazoles/pharmacokinetics , Quinolines/chemical synthesis , Quinolines/pharmacokinetics , RNA, Messenger/genetics , RNA, Messenger/metabolism , Rats , Rats, Sprague-Dawley , Receptors, Notch/metabolism , Structure-Activity Relationship , Sulfonamides/chemistry , Time Factors , Transcription Factor HES-1ABSTRACT
Structure-activity relationship (SAR) of a novel, potent and metabolically stable series of benzo [3.2.1] bicyclic sulfonamide-pyrazoles as γ-secretase inhibitors are described. Compounds that are efficacious in reducing the cortical Aßx-40 levels in FVB mice via oral dose, as well as those with high selectivity over Notch, are highlighted.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Pyrazoles/pharmacology , Sulfonamides/pharmacology , Amyloid Precursor Protein Secretases/metabolism , Animals , Bridged Bicyclo Compounds, Heterocyclic/chemistry , Bridged Bicyclo Compounds, Heterocyclic/pharmacology , Mice , Pyrazoles/chemistry , Structure-Activity Relationship , Sulfonamides/chemistryABSTRACT
INTRODUCTION: Inhibition of gamma-secretase presents a direct target for lowering Aß production in the brain as a therapy for Alzheimer's disease (AD). However, gamma-secretase is known to process multiple substrates in addition to amyloid precursor protein (APP), most notably Notch, which has limited clinical development of inhibitors targeting this enzyme. It has been postulated that APP substrate selective inhibitors of gamma-secretase would be preferable to non-selective inhibitors from a safety perspective for AD therapy. METHODS: In vitro assays monitoring inhibitor potencies at APP γ-site cleavage (equivalent to Aß40), and Notch ε-site cleavage, in conjunction with a single cell assay to simultaneously monitor selectivity for inhibition of Aß production vs. Notch signaling were developed to discover APP selective gamma-secretase inhibitors. In vivo efficacy for acute reduction of brain Aß was determined in the PDAPP transgene model of AD, as well as in wild-type FVB strain mice. In vivo selectivity was determined following seven days x twice per day (b.i.d.) treatment with 15 mg/kg/dose to 1,000 mg/kg/dose ELN475516, and monitoring brain Aß reduction vs. Notch signaling endpoints in periphery. RESULTS: The APP selective gamma-secretase inhibitors ELN318463 and ELN475516 reported here behave as classic gamma-secretase inhibitors, demonstrate 75- to 120-fold selectivity for inhibiting Aß production compared with Notch signaling in cells, and displace an active site directed inhibitor at very high concentrations only in the presence of substrate. ELN318463 demonstrated discordant efficacy for reduction of brain Aß in the PDAPP compared with wild-type FVB, not observed with ELN475516. Improved in vivo safety of ELN475516 was demonstrated in the 7d repeat dose study in wild-type mice, where a 33% reduction of brain Aß was observed in mice terminated three hours post last dose at the lowest dose of inhibitor tested. No overt in-life or post-mortem indications of systemic toxicity, nor RNA and histological end-points indicative of toxicity attributable to inhibition of Notch signaling were observed at any dose tested. CONCLUSIONS: The discordant in vivo activity of ELN318463 suggests that the potency of gamma-secretase inhibitors in AD transgenic mice should be corroborated in wild-type mice. The discovery of ELN475516 demonstrates that it is possible to develop APP selective gamma-secretase inhibitors with potential for treatment for AD.
ABSTRACT
Potent, small molecule A beta inhibitors have been prepared that incorporate an alanine core bracketed by an N-terminal arylacetyl group and various C-terminal amino alcohols. The compounds exhibit stereospecific inhibition as demonstrated in an in vitro assay.