Hepatitis C genotype 1a replicon improved through introduction of fitness mutations.

The use of subgenomic replicon systems has long been a valuable screening tool for the discovery of small molecule antivirals against Hepatitis C virus. While genotype 1a replicon systems have been widely used in stable systems, use in transient assays has been hampered by low signal. Here we describe the generation of a more robust genotype 1a (H77) replicon through the introduction of two fitness mutations, NS4A-K1691R and NS4B-E1726G, for use in transient transfections.

Virologic escape during danoprevir (ITMN-191/RG7227) monotherapy is hepatitis C virus subtype dependent and associated with R155K substitution.

Danoprevir is a hepatitis C virus (HCV) NS3/4A protease inhibitor that promotes multi-log(10) reductions in HCV RNA when administered as a 14-day monotherapy to patients with genotype 1 chronic HCV. Of these patients, 14/37 experienced a continuous decline in HCV RNA, 13/37 a plateau, and 10/37 a rebound. The rebound and continuous-decline groups experienced similar median declines in HCV RNA through day 7, but their results diverged notably at day 14.

Design, synthesis and discovery of 1-(2-(6-Chloro-3-methylsulfonyl)-naphthyl)-1H-pyrazole-5-carboxylamides as highly potent factor Xa inhibitors.

Based upon the biphenyl 1-(2-naphthyl)-1H-pyrazole-5-carboxylamides reported in our previous communications, we designed and discovered 2-(6-chloro-3-methylsulfonyl)-naphthyl as an optimal factor Xa S1 binding element. Employing a key Diels-Alder reaction of 1,4-dihydro-2,3-benzoxathiin-3-oxide with maleic anhydride and a key Cu(I)-mediated methylsulfonylation, we prepared two biphenyl 1-(2-(6-chloro-3-methylsulfonyl)-naphthyl)-1H-pyrazole-5-carboxylamides as highly potent factor Xa inhibitors with K(i) values of 0.065 nM and 0.

Discovery of betrixaban (PRT054021), N-(5-chloropyridin-2-yl)-2-(4-(N,N-dimethylcarbamimidoyl)benzamido)-5-methoxybenzamide, a highly potent, selective, and orally efficacious factor Xa inhibitor.

Systematic SAR studies of in vitro factor Xa inhibitory activity around compound 1 were performed by modifying each of the three phenyl rings. A class of highly potent, selective, efficacious and orally bioavailable direct factor Xa inhibitors was discovered. These compounds were screened in hERG binding assays to examine the effects of substitution groups on the hERG channel affinity.

Parallel synthesis and structure-activity relationships of a series of highly potent, selective, and neutral factor Xa inhibitors.

Parallel synthesis and iterative optimization led to the discovery of a series of potent and specific factor Xa inhibitors demonstrating excellent in vitro activity with promising pharmacokinetics.

N,N-Dialkylated 4-(4-arylsulfonylpiperazine-1-carbonyl)-benzamidines and 4-((4-arylsulfonyl)-2-oxo-piperazin-1-ylmethyl)-benzamidines as potent factor Xa inhibitors.

A class of N,N-dialkylated 4-(4-arylsulfonylpiperazine-1-carbonyl)-benzamidines and 4-((4-arylsulfonyl)-2-oxo-piperazin-1-ylmethyl)-benzamidines has been discovered as potent factor Xa inhibitors with desirable in vitro and in vivo anticoagulant activity, but with low oral bioavailability. The 5-chloroindole and 6-chlorobenzo[b]thiophene groups are optimal as the factor Xa S1 binding elements. The strategy of incorporating a side chain on the piperazine nucleus to enhance binding affinity has been examined.

Design, synthesis, and SAR of anthranilamide-based factor Xa inhibitors with improved functional activity.

Compound 2 containing an aminomethylbenzoyl moiety as the S4 binding motif was synthesized in order to modulate hydrophlicity of anthranilamide-based factor Xa inhibitors with substituted biphenyl P4 groups. Structure-activity relationship studies around 2 have led to a series of potent factor Xa inhibitors which are highly active in the human plasma-based thrombin generation assay with 2XTG values less than 1 microM. Compound 55 shows strong antithrombotic activity in our rabbit deep vein thrombosis model, and also exhibits good oral bioavailability and a long half life in rats.

Design, synthesis, and SAR of anthranilamide-based factor Xa inhibitors incorporating substituted biphenyl P4 motifs.

Anthranilamides 4 and 5 were designed and synthesized as selective and orally bioavailable factor Xa inhibitors. Structural modifications aimed at lowering their lipophilicity were performed at the central phenyl ring and at the S4 binding biphenyl region by incorporating water solublizing substituents. The resulting compounds (e.

1-(2-Naphthyl)-1H-pyrazole-5-carboxylamides as potent factor Xa inhibitors. Part 3: Design, synthesis and SAR of orally bioavailable benzamidine-P4 inhibitors.

Using N,N-dialkylated benzamidines as the novel P4 motifs, we have designed and synthesized a class of 1-(2-naphthyl)-1H-pyrazole-5-carboxylamides as highly potent and selective fXa inhibitors with significantly improved hydrophilicity and in vitro anticoagulant activity. These benzamidine-P4 fXa inhibitors have displayed excellent oral bioavailability and long half-life.

1-(2-Naphthyl)-1H-pyrazole-5-carboxylamides as potent factor Xa inhibitors. Part 2: A survey of P4 motifs.

A variety of P4 motifs have been examined to increase the binding affinity and in vitro anticoagulant potency of our biphenyl 1-(2-naphthyl)-1H-pyrazole-5-carboxylamide-based fXa inhibitors. Highly potent 2-naphthyl-P1 fXa inhibitors (K(i)< or =2 nM) with improved in vitro anticoagulant activity (2xTG< or =1 microM) and respectable pharmacokinetic properties have been discovered.

Inhibition of purified factor Xa amidolytic activity may not be predictive of inhibition of in vivo thrombosis: implications for identification of therapeutically active inhibitors.

Objective: In this study we test the hypothesis that blood/plasma-based prothrombinase assays, rather than inhibition of purified factor Xa (fXa), are predictive of in vivo antithrombotic activity.

Methods And Results: Six fXa inhibitors with equivalent nanomolar Ki were studied in thrombin generation assays using human plasma/blood and endogenous macromolecular substrate. In all assays, benzamidine inhibitors were more potent (100 to 800 nmol/L) than the aminoisoquinolines (5 to 58 micromol/L) or neutral inhibitors (3 to 10 micromol/L).

Design, synthesis, and structure-activity relationships of unsubstituted piperazinone-based transition state factor Xa inhibitors.

A series of novel transition state factor Xa inhibitors containing a variety of lactam ring systems as central templates was synthesized in an expedient manner and allowed for a great deal of structural variability. Among them, the piperazinone-based inhibitors were found to be not only active against factor Xa but also selective over thrombin. Optimization of the P4 moiety yielded several potent compounds with IC(50) below 1 nM against factor Xa.