RESUMO
Inhibition of BACE1 has become an important strategy in the quest for disease modifying agents to slow the progression of Alzheimer's disease. We previously reported the fragment-based discovery of LY2811376, the first BACE1 inhibitor reported to demonstrate robust reduction of human CSF Aß in a Phase I clinical trial. We also reported on the discovery of LY2886721, a potent BACE1 inhibitor that reached phase 2 clinical trials. Herein we describe the preparation and structure activity relationships (SAR) of a series of BACE1 inhibitors utilizing trans-cyclopropyl moieties as conformational constraints. The design, details of the stereochemically complex organic synthesis, and biological activity of these BACE1 inhibitors is described.
Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Ciclopropanos/farmacologia , Inibidores de Proteases/farmacologia , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Secretases da Proteína Precursora do Amiloide/metabolismo , Ácido Aspártico Endopeptidases/metabolismo , Cristalografia por Raios X , Ciclopropanos/síntese química , Ciclopropanos/química , Relação Dose-Resposta a Droga , Humanos , Ligantes , Modelos Moleculares , Conformação Molecular , Inibidores de Proteases/síntese química , Inibidores de Proteases/química , Relação Estrutura-AtividadeRESUMO
BACE1 is a key protease controlling the formation of amyloid ß, a peptide hypothesized to play a significant role in the pathogenesis of Alzheimer's disease (AD). Therefore, the development of potent and selective inhibitors of BACE1 has been a focus of many drug discovery efforts in academia and industry. Herein, we report the nonclinical and early clinical development of LY2886721, a BACE1 active site inhibitor that reached phase 2 clinical trials in AD. LY2886721 has high selectivity against key off-target proteases, which efficiently translates in vitro activity into robust in vivo amyloid ß lowering in nonclinical animal models. Similar potent and persistent amyloid ß lowering was observed in plasma and lumbar CSF when single and multiple doses of LY2886721 were administered to healthy human subjects. Collectively, these data add support for BACE1 inhibition as an effective means of amyloid lowering and as an attractive target for potential disease modification therapy in AD.
Assuntos
Doença de Alzheimer/tratamento farmacológico , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Peptídeos beta-Amiloides/metabolismo , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Compostos Heterocíclicos com 2 Anéis/farmacologia , Ácidos Picolínicos/farmacologia , Inibidores de Proteases/farmacologia , Peptídeos beta-Amiloides/sangue , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Animais , Modelos Animais de Doenças , Cães , Compostos Heterocíclicos com 2 Anéis/farmacocinética , Compostos Heterocíclicos com 2 Anéis/uso terapêutico , Humanos , Camundongos , Ácidos Picolínicos/farmacocinética , Ácidos Picolínicos/uso terapêutico , Inibidores de Proteases/farmacocinética , Inibidores de Proteases/uso terapêuticoRESUMO
The BACE1 enzyme is a key target for Alzheimer's disease. During our BACE1 research efforts, fragment screening revealed that bicyclic thiazine 3 had low millimolar activity against BACE1. Analysis of the co-crystal structure of 3 suggested that potency could be increased through extension toward the S3 pocket and through conformational constraint of the thiazine core. Pursuit of S3-binding groups produced low micromolar inhibitor 6, which informed the S3-design for constrained analogs 7 and 8, themselves prepared via independent, multi-step synthetic routes. Biological characterization of BACE inhibitors 6-8 is described.
Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Compostos Bicíclicos com Pontes/síntese química , Inibidores de Proteases/síntese química , Tiazinas/síntese química , Secretases da Proteína Precursora do Amiloide/química , Secretases da Proteína Precursora do Amiloide/isolamento & purificação , Animais , Ácido Aspártico Endopeptidases/química , Ácido Aspártico Endopeptidases/isolamento & purificação , Química Encefálica , Compostos Bicíclicos com Pontes/química , Cristalografia por Raios X , Desenho de Fármacos , Humanos , Camundongos , Conformação Molecular , Simulação de Acoplamento Molecular , Inibidores de Proteases/química , Estereoisomerismo , Tiazinas/químicaRESUMO
According to the amyloid cascade hypothesis, cerebral deposition of amyloid-ß peptide (Aß) is critical for Alzheimer's disease (AD) pathogenesis. Aß generation is initiated when ß-secretase (BACE1) cleaves the amyloid precursor protein. For more than a decade, BACE1 has been a prime target for designing drugs to prevent or treat AD. However, development of such agents has turned out to be extremely challenging, with major hurdles in cell penetration, oral bioavailability/metabolic clearance, and brain access. Using a fragment-based chemistry strategy, we have generated LY2811376 [(S)-4-(2,4-difluoro-5-pyrimidin-5-yl-phenyl)-4-methyl-5,6-dihydro-4H-[1,3]thiazin-2-ylamine], the first orally available non-peptidic BACE1 inhibitor that produces profound Aß-lowering effects in animals. The biomarker changes obtained in preclinical animal models translate into man at doses of LY2811376 that were safe and well tolerated in healthy volunteers. Prominent and long-lasting Aß reductions in lumbar CSF were measured after oral dosing of 30 or 90 mg of LY2811376. This represents the first translation of BACE1-driven biomarker changes in CNS from preclinical animal models to man. Because of toxicology findings identified in longer-term preclinical studies, this compound is no longer progressing in clinical development. However, BACE1 remains a viable target because the adverse effects reported here were recapitulated in LY2811376-treated BACE1 KO mice and thus are unrelated to BACE1 inhibition. The magnitude and duration of central Aß reduction obtainable with BACE1 inhibition positions this protease as a tractable small-molecule target through which to test the amyloid hypothesis in man.
Assuntos
Doença de Alzheimer/líquido cefalorraquidiano , Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Peptídeos beta-Amiloides/metabolismo , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Neurônios/efeitos dos fármacos , Adulto , Doença de Alzheimer/tratamento farmacológico , Secretases da Proteína Precursora do Amiloide/análise , Peptídeos beta-Amiloides/líquido cefalorraquidiano , Precursor de Proteína beta-Amiloide/líquido cefalorraquidiano , Precursor de Proteína beta-Amiloide/genética , Análise de Variância , Animais , Ácido Aspártico Endopeptidases/análise , Células Cultivadas , Córtex Cerebral/citologia , Cristalografia/métodos , Modelos Animais de Doenças , Cães , Relação Dose-Resposta a Droga , Embrião de Mamíferos , Inibidores Enzimáticos/sangue , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Modelos Químicos , Mutação/genética , Fragmentos de Peptídeos/líquido cefalorraquidiano , Pirimidinas/farmacologia , Pirimidinas/uso terapêutico , Ratos , Ratos Sprague-Dawley , Tiazinas/farmacologia , Tiazinas/uso terapêutico , Fatores de Tempo , Adulto JovemRESUMO
BACKGROUND: The development of beta-site amyloid-beta precursor protein cleaving enzyme (BACE) 1 inhibitors for the treatment of Alzheimer's disease requires optimization of inhibitor potency, selectivity, and brain penetration. Moreover, there is a need for low-dose compounds since liver toxicity was found with some BACE inhibitors. OBJECTIVE: To determine whether the high in vitro potency and robust pharmacodynamic effect of the BACE inhibitor LY3202626 observed in nonclinical species translated to humans. METHODS: The effect of LY3202626 versus vehicle on amyloid-ß (Aß) levels was evaluated in a series of in vitro assays, as well as in in vivo and multi-part clinical pharmacology studies. Aß levels were measured using analytical biochemistry assays in brain, plasma, and cerebrospinal fluid (CSF) of mice, dogs and humans. Nonclinical data were analyzed using an ANOVA followed by Tukey's post hoc test and clinical data used summary statistics. RESULTS: LY3202626 exhibited significant human BACE1 inhibition, with an IC50 of 0.615±0.101 nM in a fluorescence resonance energy transfer assay and an EC50 of 0.275±0.176ânM for lowering Aß1-40 and 0.228±0.244ânM for Aß1-42 in PDAPP neuronal cultures. In dogs, CSF Aß1hboxx concentrations were significantly reduced by â¼80% at 9 hours following a 1.5âmg/kg dose. In humans, CSF Aß1-42 was reduced by 73.1±7.96 % following administration of 6âmg QD. LY3202626 was found to freely cross the blood-brain barrier in dogs and humans. CONCLUSION: LY3202626 is a potent BACE1 inhibitor with high blood-brain barrier permeability. The favorable safety and pharmacokinetic/pharmacodynamic profile of LY3202626 supports further clinical development.
RESUMO
The beta-site APP cleaving enzyme 1, known as BACE1, has been a widely pursued Alzheimer's disease drug target owing to its critical role in the production of amyloid-beta. We have previously reported the clinical development of LY2811376 and LY2886721. LY2811376 advanced to Phase I before development was terminated due to nonclinical retinal toxicity. LY2886721 advanced to Phase II, but development was halted due to abnormally elevated liver enzymes. Herein, we report the discovery and clinical development of LY3202626, a highly potent, CNS-penetrant, and low-dose BACE inhibitor, which successfully addressed these key development challenges.
Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Compostos Heterocíclicos com 2 Anéis/farmacologia , Inibidores de Proteases/farmacologia , Pirazinas/farmacologia , Pirróis/farmacologia , Secretases da Proteína Precursora do Amiloide/metabolismo , Animais , Ácido Aspártico Endopeptidases/metabolismo , Barreira Hematoencefálica/fisiologia , Encéfalo/metabolismo , Cristalografia por Raios X , Cães , Estabilidade de Medicamentos , Compostos Heterocíclicos com 2 Anéis/síntese química , Compostos Heterocíclicos com 2 Anéis/farmacocinética , Humanos , Células Madin Darby de Rim Canino , Masculino , Camundongos , Microssomos Hepáticos/metabolismo , Estrutura Molecular , Inibidores de Proteases/síntese química , Inibidores de Proteases/metabolismo , Inibidores de Proteases/farmacocinética , Ligação Proteica , Pirazinas/síntese química , Pirazinas/farmacocinética , Pirróis/síntese química , Pirróis/farmacocinética , Ratos , Relação Estrutura-AtividadeRESUMO
The total synthesis of (+)-yohimbine was achieved in 11 steps and 14% overall yield. The absolute configuration was established through a highly enantioselective thiourea-catalyzed acyl-Pictet-Spengler reaction, and the remaining 4 stereocenters were set simultaneously in a substrate-controlled intramolecular Diels-Alder reaction.
Assuntos
Ioimbina/síntese química , Catálise , Ciclização , Estrutura Molecular , Estereoisomerismo , Ioimbina/químicaRESUMO
[reaction: see text] A concise synthesis of the spinosyn A tricyclic nucleus 27 has been developed by a route featuring a one-pot tandem intramolecular Diels-Alder reaction and intramolecular vinylogous Morita-Baylis-Hillman cyclization in which five stereocenters in tricycle 10 are set with excellent selectivity.
Assuntos
Antibacterianos/síntese química , Macrolídeos , Ciclização , Inseticidas/síntese química , Saccharopolyspora/química , Estereoisomerismo , Compostos de Vinila/químicaRESUMO
A study of elements of stereochemical control in transannular Diels-Alder reactions leading to the decahydro-as-indacene core of (-)-spinosyn A is described. Initial studies focused on macrocyclic pentaene 9, which includes C(6)-Br and C(8)-OTBS substituents. Excellent selectivity (>95:5) was observed in the cycloaddition of 9 as a consequence of 1,3-allylic strain interactions involving the C(6) and C(8) substituents in the disfavored TS-2. The major cycloadduct 22 was used in a formal synthesis of (-)-spinosyn A. The TDA cyclizations of 12 (which lacks the C(8)-OTBS unit of 9), 13 (which lacks the C(6)-Br substituent of 12), and 14 (which lacks the C(6)-Br and C(21)-Et substituents of 12) were also studied. Macrocycles 12 and 13 served as precursors to (-)-spinosyn A and the (-)-spinosyn A aglycon (34), respectively. It is striking that substrates 12-14 give very similar distributions of transannular Diels-Alder cycloadducts, indicating that the C(6)-Br and C(21)-stereocenter do not play a significant role in the diastereoselectivity of the TDA cycloaddition of spinosyn A precursor 12. It is likely that some as yet unidentified conformational or structural features of macrocycles 12-14 contribute to the levels of diastereoselectivity achieved, since these TDA reactions are more selective for the C(7)-C(9) stereochemical relationship found in the natural product than are the IMDA reactions of trienes 4 and 7.
Assuntos
Macrolídeos/síntese química , Ciclização , Macrolídeos/química , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Espectrometria de Massas por Ionização por Electrospray , Espectrofotometria Infravermelho , EstereoisomerismoRESUMO
A convergent, highly stereoselective total synthesis of (-)-spinosyn A (1) is described. Key features of the synthesis include the transannular Diels-Alder reaction of macrocyclic pentaene 11 and the transannular Morita-Baylis-Hillman cyclization of 12 that generates tetracycle 26. The total synthesis of (-)-spinosyn A was completed by a sequence involving the highly beta-selective glycosidation reaction of 13 and glycosyl imidate 30.
Assuntos
Macrolídeos/síntese química , Química Orgânica/métodos , Inseticidas/síntese química , Inseticidas/química , Macrolídeos/química , Estrutura Molecular , EstereoisomerismoRESUMO
The development of the vinylogous intramolecular Morita-Baylis-Hillman reaction for the synthesis of functionalized cyclopentenes and cyclohexenes is described. The reaction involves the trialkyphosphine-catalyzed cyclization of 1,6- or 1,7-diactivated 1,5-hexadienes or 1,6-heptadienes, containing carboxyaldehyde, methyl ketone, or methoxycarbonyl as the olefin activating groups. A representative example of this reaction is the Me(3)P-catalyzed cyclization of 1a in tert-amyl alcohol, which provides the substituted cyclopentene 2a in 95% yield and with 97:3 regioselectivity.