Subject(s)
Alzheimer Disease/drug therapy , Alzheimer Disease/enzymology , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Amyloid beta-Peptides/metabolism , Drug Discovery/methods , Models, Biological , Protease Inhibitors/pharmacology , Protease Inhibitors/therapeutic use , Alzheimer Disease/metabolism , Alzheimer Disease/physiopathology , Amyloid beta-Peptides/biosynthesis , Animals , Drug Discovery/trends , Humans , Protease Inhibitors/chemistry , Protease Inhibitors/classificationABSTRACT
The presenilin containing gamma-secretase complex is responsible for the regulated intramembraneous proteolysis of the amyloid precursor protein (APP), the Notch receptor, and a multitude of other substrates. gamma-Secretase catalyzes the final step in the generation of Abeta(40) and Abeta(42) peptides from APP. Amyloid beta-peptides (Abeta peptides) aggregate to form neurotoxic oligomers, senile plaques, and congophilic angiopathy, some of the cardinal pathologies associated with Alzheimer's disease. Although inhibition of this protease acting on APP may result in potentially therapeutic reductions of neurotoxic Abeta peptides, nonselective inhibition of the enzyme may cause severe adverse events as a result of impaired Notch receptor processing. Here, we report the preclinical pharmacological profile of GSI-953 (begacestat), a novel thiophene sulfonamide gamma-secretase inhibitor (GSI) that selectively inhibits cleavage of APP over Notch. This GSI inhibits Abeta production with low nanomolar potency in cellular and cell-free assays of gamma-secretase function, and displaces a tritiated analog of GSI-953 from enriched gamma-secretase enzyme complexes with similar potency. Cellular assays of Notch cleavage reveal that this compound is approximately 16-fold selective for the inhibition of APP cleavage. In the human APP-overexpressing Tg2576 transgenic mouse, treatment with this orally active compound results in a robust reduction in brain, plasma, and cerebral spinal fluid Abeta levels, and a reversal of contextual fear-conditioning deficits that are correlated with Abeta load. In healthy human volunteers, oral administration of a single dose of GSI-953 produces dose-dependent changes in plasma Abeta levels, confirming pharmacodynamic activity of GSI-953 in humans.
Subject(s)
Alzheimer Disease/drug therapy , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Sulfonamides/pharmacology , Thiophenes/pharmacology , Adolescent , Adult , Amyloid Precursor Protein Secretases/metabolism , Amyloid beta-Protein Precursor/genetics , Amyloid beta-Protein Precursor/metabolism , Animals , Binding, Competitive , CHO Cells , Cell Line , Cricetinae , Cricetulus , Dogs , Enzyme Inhibitors/pharmacokinetics , Enzyme Inhibitors/toxicity , Fear/psychology , Female , Humans , Male , Mice , Mice, Transgenic , Middle Aged , Rats , Rats, Sprague-Dawley , Receptors, Notch/physiology , Signal Transduction/drug effects , Sulfonamides/pharmacokinetics , Sulfonamides/toxicity , Thiophenes/pharmacokinetics , Thiophenes/toxicity , Young AdultABSTRACT
gamma-Secretase inhibitors have been shown to reduce the production of beta-amyloid, a component of the plaques that are found in brains of patients with Alzheimer's disease. A novel series of heterocyclic sulfonamide gamma-secretase inhibitors that reduce beta-amyloid levels in cells is reported. Several examples of compounds within this series demonstrate a higher propensity to inhibit the processing of amyloid precursor protein compared to Notch, an alternative gamma-secretase substrate.
Subject(s)
Alzheimer Disease/drug therapy , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Amyloid Precursor Protein Secretases/metabolism , Heterocyclic Compounds/chemistry , Heterocyclic Compounds/pharmacology , Sulfonamides/chemistry , Sulfonamides/pharmacology , Amyloid beta-Peptides/antagonists & inhibitors , Amyloid beta-Peptides/metabolism , Animals , CHO Cells , Cricetinae , Cricetulus , Heterocyclic Compounds/chemical synthesis , Humans , Molecular Structure , Protein Binding , Receptors, Notch/metabolism , Structure-Activity Relationship , Sulfonamides/chemical synthesisABSTRACT
Accumulation of beta-amyloid (Abeta), produced by the proteolytic cleavage of amyloid precursor protein (APP) by beta- and gamma-secretase, is widely believed to be associated with Alzheimer's disease (AD). Research around the high-throughput screening hit (S)-4-chlorophenylsulfonyl isoleucinol led to the identification of the Notch-1-sparing (9.5-fold) gamma-secretase inhibitor (S)-N-(5-chlorothiophene-2-sulfonyl)-beta,beta-diethylalaninol 7.b.2 (Abeta(40/42) EC(50)=28 nM), which is efficacious in reduction of Abeta production in vivo.
Subject(s)
Alzheimer Disease/drug therapy , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Isoleucine/analogs & derivatives , Receptor, Notch1/metabolism , Alcohols , Amyloid Precursor Protein Secretases/metabolism , Amyloid beta-Protein Precursor/chemistry , Animals , Drug Design , Humans , Isoleucine/chemistry , Models, Chemical , Propanolamines/chemistry , Sulfonamides/chemistryABSTRACT
SAR on HTS hits 1 and 2 led to the potent, Notch-1-sparing GSI 9, which lowered brain Abeta in Tg2576 mice at 100 mg/kg po. Converting the metabolically labile methyl groups in 9 to trifluoromethyl groups afforded the more stable analogue 10, which had improved in vivo potency. Further side chain modification afforded the potent Notch-1-sparing GSI begacestat (5), which was selected for development for the treatment of Alzheimer's disease.
Subject(s)
Alzheimer Disease/drug therapy , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Drug Discovery , Enzyme Inhibitors/pharmacology , Receptor, Notch1/metabolism , Sulfonamides/pharmacology , Thiophenes/pharmacology , Alzheimer Disease/enzymology , Amyloid Precursor Protein Secretases/metabolism , Amyloid beta-Peptides/metabolism , Animals , Crystallography, X-Ray , Disease Models, Animal , Dose-Response Relationship, Drug , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/chemistry , Mice , Mice, Transgenic , Models, Molecular , Molecular Conformation , Stereoisomerism , Structure-Activity Relationship , Sulfonamides/chemical synthesis , Sulfonamides/chemistry , Thiophenes/chemical synthesis , Thiophenes/chemistryABSTRACT
Using a cell-based assay, we have identified a new series of Notch-sparing gamma-secretase inhibitors from HTS screening leads 2a and 2e. Lead optimization studies led to the discovery of analog 8e with improved gamma-secretase inhibitory potency and Notch-sparing selectivity.
Subject(s)
Amyloid Precursor Protein Secretases/antagonists & inhibitors , Chemistry, Pharmaceutical/methods , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Receptors, Notch/metabolism , Alzheimer Disease/drug therapy , Amyloid/chemistry , Amyloid Precursor Protein Secretases/chemistry , Carbon/chemistry , Drug Design , Drug Evaluation, Preclinical , Humans , Models, Chemical , Receptors, Notch/antagonists & inhibitors , Structure-Activity RelationshipABSTRACT
An asymmetric synthesis of alpha-amino acids with novel beta-branched side chains has been implemented. The syntheses feature a p-toluenesulfinylimine induced chiral Strecker approach and were found to be applicable to the introduction of both aliphatic and aromatic beta-branched sidechains for preparation of previously unknown alpha-amino acids.
Subject(s)
Amino Acids/chemistry , Amino Acids/chemical synthesis , Chemistry, Pharmaceutical/methods , Chemistry, Organic/methods , Drug Design , Models, Chemical , Molecular ConformationABSTRACT
Transgenic mice (Tg2576) overexpressing the Swedish mutation of the human amyloid precursor protein display biochemical, pathological, and behavioral markers consistent with many aspects of Alzheimer's disease, including impaired hippocampal function. Impaired, hippocampal-dependent, contextual fear conditioning (CFC) is observed in mice as young as 20 weeks of age. This impairment can be attenuated after treatment before training with the phosphodiesterase-4 inhibitor rolipram (0.1 mg/kg, i.p.). A rolipram-associated improvement is also observed in the littermate controls, suggesting that the effect of rolipram is independent of beta-amyloid. Acute treatment before training (but not after training or before testing) with the gamma-secretase inhibitor (GSI) N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine-t-butylester (DAPT), at a dose that reduces brain concentrations of beta-amyloid (100 mg/kg), attenuates the impairment in 20- to 65-week-old Tg2576 mice. Importantly, DAPT had no effect on performance of control littermates. These data are supportive of a role of beta-amyloid in the impairment of CFC in Tg2576 mice. Furthermore, they suggest that acute treatment with GSI may provide improved cognitive functioning as well as disease-modifying effects in Alzheimer's disease.
Subject(s)
Alzheimer Disease/metabolism , Alzheimer Disease/psychology , Conditioning, Psychological/drug effects , Endopeptidases/metabolism , Enzyme Inhibitors/pharmacology , Fear , 3',5'-Cyclic-AMP Phosphodiesterases/antagonists & inhibitors , Aging/psychology , Alzheimer Disease/genetics , Amyloid Precursor Protein Secretases , Amyloid beta-Peptides/metabolism , Amyloid beta-Protein Precursor/genetics , Amyloid beta-Protein Precursor/metabolism , Animals , Aspartic Acid Endopeptidases , Cognition/drug effects , Cognition Disorders/chemically induced , Cognition Disorders/psychology , Cyclic Nucleotide Phosphodiesterases, Type 4 , Disease Models, Animal , Mice , Mice, Transgenic , Mutation , Phosphodiesterase Inhibitors/pharmacology , Rolipram/pharmacology , Triglycerides/pharmacology , gamma-Aminobutyric Acid/analogs & derivatives , gamma-Aminobutyric Acid/pharmacologyABSTRACT
Alzheimer's disease (AD) is a debilitating disease widely thought to be associated with the accumulation of beta amyloid (Abeta) in the brain. Inhibition of gamma-secretase, one of the enzymes responsible for Abeta production, may be a useful strategy for the treatment of AD. Described below is a series of gamma-secretase inhibitors designed from a scaffold identified by a ROCS [J. Comput. Chem.1996, 17, 1653] search of the corporate database.
Subject(s)
Amyloid beta-Peptides/antagonists & inhibitors , Brain/drug effects , Endopeptidases/drug effects , Piperidines/chemical synthesis , Protease Inhibitors/chemical synthesis , Alzheimer Disease/enzymology , Amyloid Precursor Protein Secretases , Animals , Brain/metabolism , Drug Design , Endopeptidases/metabolism , Models, Molecular , Piperidines/pharmacology , Protease Inhibitors/pharmacology , Protein Binding , Structure-Activity RelationshipABSTRACT
A method using reverse phase liquid chromatography-tandem mass spectrometry and cassette administration was developed for in vivo brain and plasma exposure profiling to assist early CNS drug discovery programs. Three to four compounds were grouped in cassettes for dosing and analysis. Compounds in the cassettes were selected to minimize possible analytical interference from each other, as well as from their potential metabolites. In order to improve the confidence of cassette administration, an analogue of the study compounds, with well-established brain penetration data, was included in each cassette as a "biological internal standard". Compounds were administered to rats by intraperitoneal injection and extracted from plasma or brain homogenate by simple protein precipitation. Fast chromatographic separation was achieved by using a short narrow-bore column at a flow rate of 1.0ml/min with a fast gradient. The brain penetration of the compounds was evaluated by comparing their C(max) and AUC values in brain and plasma. This approach rapidly provided early brain penetration and plasma exposure information, thus making more of this data available to teams. Comparing the brain exposures to the EC(50) values (i.e. in vitro potency) of series compounds in the same discovery program provided another dimension of information to select lead compounds for future in vivo assessment. The method described here has been used for providing early brain penetration information in several CNS exploratory and discovery programs.
