ABSTRACT
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
Herein we describe the structure-activity relationship (SAR) of amino-caprolactam analogs derived from amino-caprolactam benzene sulfonamide 1, highlighting affects on the potency of γ-secretase inhibition, selectivity for the inhibition of APP versus Notch processing by γ-secretase and selected pharmakokinetic properties. Amino-caprolactams that are efficacious in reducing the cortical Aß(x-40) levels in FVB mice via a single 100 mpk IP dose are highlighted.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Caprolactam/analogs & derivatives , Enzyme Inhibitors/pharmacology , Alzheimer Disease/drug therapy , Amyloid beta-Peptides/metabolism , Animals , Caprolactam/chemical synthesis , Caprolactam/chemistry , Caprolactam/pharmacology , Enzyme Activation/drug effects , Enzyme Inhibitors/chemical synthesis , Infusions, Parenteral , Inhibitory Concentration 50 , Mice , Molecular Structure , Peptide Fragments/metabolismABSTRACT
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
Significant improvement in metabolic stability on the pyrazolopiperidine scaffold over the original series were achieved and this stability improvement translated in an improved in vivo efficacy.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Piperidines/chemistry , Sulfonamides/chemistry , Animals , Drug Discovery , Drug Stability , Microsomes, Liver/metabolism , Piperidines/chemical synthesis , Piperidines/pharmacology , Protease Inhibitors/chemical synthesis , Protease Inhibitors/chemistry , Protease Inhibitors/pharmacology , Sulfonamides/chemical synthesis , Sulfonamides/pharmacologyABSTRACT
Discovery of a series of pyrazolopiperidine sulfonamide based gamma-secretase inhibitors and its SAR evolution is described. Significant increases in APP potency on the pyrazolopiperidine scaffold over the original N-bicyclic sulfonamide scaffold were achieved and this potency increase translated in an improved in vivo efficacy.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Amyloid Precursor Protein Secretases/metabolism , Piperidines/chemistry , Piperidines/pharmacology , Sulfonamides/chemistry , Sulfonamides/pharmacology , Alzheimer Disease/drug therapy , Animals , Humans , Mice , Models, Molecular , Piperidines/therapeutic use , Structure-Activity Relationship , Sulfonamides/therapeutic useABSTRACT
Production of amyloid beta peptides (Abeta), followed by their deposition in the brain as amyloid plaques, contributes to the hallmark pathology of Alzheimer disease. The enzymes responsible for production of Abeta, BACE1 and gamma-secretase, are therapeutic targets for treatment of Alzheimer disease. Two presenilin (PS) homologues, referred to as PS1 and PS2, comprise the catalytic core of gamma-secretase. In comparing presenilin selectivity of several classes of gamma-secretase inhibitors, we observed that sulfonamides in general tend to be more selective for inhibition of PS1-comprising gamma-secretase, as exemplified by ELN318463 and BMS299897. We employed a combination of chimeric constructs and point mutants to identify structural determinants for PS1-selective inhibition by ELN318463. Our studies identified amino acid residues Leu(172), Thr(281), and Leu(282) in PS1 as necessary for PS1-selective inhibition by ELN318463. These residues also contributed in part to the PS1-selective inhibition by BMS299897. Alanine scanning mutagenesis of areas flanking Leu(172), Thr(281), and Leu(282) identified additional amino acids that affect inhibitor potency of not only these sulfonamides but also nonsulfonamide inhibitors, without affecting Abeta production and presenilin endoproteolysis. Interestingly, many of these same residues have been identified previously to be important for gamma-secretase function. These findings implicate TM3 and a second region near the carboxyl terminus of PS1 aminoterminal fragment in mediating the activity of gamma-secretase inhibitors. Our observations demonstrate that PS-selective inhibitors of gamma-secretase are feasible, and such inhibitors may allow differential inhibition of Abeta peptide production and Notch signaling.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Presenilin-1/antagonists & inhibitors , Presenilin-2/antagonists & inhibitors , Alzheimer Disease/drug therapy , Alzheimer Disease/metabolism , Amino Acid Sequence , Amyloid Precursor Protein Secretases/chemistry , Amyloid Precursor Protein Secretases/genetics , Amyloid Precursor Protein Secretases/metabolism , Amyloid beta-Peptides/metabolism , Animals , Carbamates/pharmacology , Dipeptides/pharmacology , Enzyme Inhibitors/pharmacology , Humans , Mice , Mice, Knockout , Molecular Sequence Data , Presenilin-1/chemistry , Presenilin-1/deficiency , Presenilin-1/genetics , Presenilin-2/chemistry , Presenilin-2/deficiency , Presenilin-2/genetics , Sequence Homology, Amino Acid , Sulfonamides/pharmacologyABSTRACT
The B1 receptor is an attractive target for the treatment of pain and inflammation. A series of 3-carboxamido-5-phenacylamino pyrazole B1 receptor antagonists are described that exhibit good potency against B1 and high selectivity over B2. Initially, N-unsubstituted pyrazoles were studied, but these compounds suffered from extensive glucuronidation in primates. This difficulty could be surmounted by the use of N-substituted pyrazoles. Optimization efforts culminated in compound 41, which has high receptor potency and metabolic stability.
