The NS5A replication complex inhibitor, BMS-790052, inhibits hepatitis C virus (HCV) replication with picomolar potency in preclinical assays. This potency translated in vivo to a substantial antiviral effect in a single-ascending dose study and a 14-day multiple-ascending dose (MAD) monotherapy study. However, HCV RNA remained detectable in genotype 1a-infected patients at the end of the MAD study. In contrast, viral breakthrough was observed less often in patients infected with genotype 1b, and, in several patients, HCV RNA declined and remained below the level of quantitation (<25 IU/mL) through the duration of treatment. Here, we report on the results of the genotypic and phenotypic analyses of resistant variants in 24 genotype 1-infected patients who received BMS-790052 (1, 10, 30, 60, and 100 mg, once-daily or 30 mg twice-daily) in the 14-day MAD study. Sequence analysis was performed on viral complementary DNA isolated from serum specimens collected at baseline and days 1 (4, 8, and 12 hours), 2, 4, 7, and 14 postdosing. Analyses of the sequence variants (1) established a correlation between resistant variants emerging in vivo with BMS-790052 treatment and those observed in the in vitro replicon system (major substitutions at residues 28, 30, 31, and 93 for genotype 1a and residues 31 and 93 for genotype 1b); (2) determined the prevalence of variants at baseline and the emergence of resistance at different times during dosing; and (3) revealed the resistance profile and replicative ability (i.e., fitness) of the variants. Conclusion: Although resistance emerged during monotherapy with BMS-790052, the substantial anti-HCV effect of this compound makes it an excellent candidate for effective combination therapy. (HEPATOLOGY 2011;54:1924-1935 T he hepatitis C virus (HCV) nonstructural protein 5A (NS5A) is a multifunctional protein with key roles in HCV replication. NS5A has also been implicated in the modulation of cellular signaling pathways. 1,2 Because it is required in vivo and in vitro for viral replication and has no known human homologs, NS5A provides an attractive target for therapeutic intervention. 3 BMS-790052 is a potent HCV NS5A replication complex inhibitor, with 50% effective concentration (EC 50 ) values of 9 and 50 pM against genotype 1b and 1a replicons, respectively. 4,5 It is also potent against live virus (genotype 2a, JFH-1), with an EC 50 of $28 pM. 4 BMS-790052 has broad genotype coverage, with EC 50 values ranging from pM to low nM for replicons with NS5A sequences derived from genotype 2a, 3a, 4a, and 5a. 4

The antiviral activity, resistance profile, pharmacokinetics (PK), safety, and tolerability of BMS‐790052, a nonstructural protein 5A (NS5A) replication complex inhibitor, were evaluated in a double‐blind, placebo‐controlled, sequential panel, multiple ascending dose study. Thirty patients with chronic hepatitis C virus (HCV) genotype 1 infection were randomized to receive a 14‐day course of BMS‐790052 (1, 10, 30, 60, or 100 mg once daily or 30 mg twice daily) or placebo in a ratio of 4:1. The mean maximum decline from baseline in HCV RNA ranged from 2.8 to 4.1 log10 IU/mL; the placebo group showed no evidence of antiviral activity. Most patients experienced viral rebound on or before day 7 of treatment with BMS‐790052 monotherapy; viral rebound was associated with viral variants that had been previously implicated in resistance development in the in vitro replicon system. The PK profile was supportive of once‐daily dosing with median peak plasma concentrations at 1‐2 hours postdose and mean terminal half‐life of 12‐15 hours. Steady state was achieved following 3‐4 days of daily dosing. BMS‐790052 was well tolerated in all dose groups, with adverse events occurring with a similar frequency in BMS‐790052‐ and placebo‐treated groups. There were no clinically relevant changes in vital signs, laboratory, or electrocardiogram parameters. Conclusion: BMS‐7590052 is the first NS5A replication complex inhibitor with multiple dose proof‐of‐concept in clinic. At doses of 1‐100 mg daily, BMS‐790052 was well tolerated, had a PK profile supportive of once‐daily dosing, and produced a rapid and substantial decrease in HCV‐RNA levels in patients chronically infected with HCV genotype 1. (HEPATOLOGY 2011

Recurrent HCV infection following liver transplantation can lead to accelerated allograft injury that is difficult to treat with interferon. The aim of this study is to describe the first ever use of an interferon‐free, all oral regimen in a liver transplant recipient with severe recurrent HCV. A 54‐year‐old male with HCV genotype 1b developed severe cholestatic HCV at 6 months posttransplant with ascites, AST 503 IU/mL, alkaline phosphatase of 298 IU/mL, HCV RNA of 12 000 000 IU/mL, and histological cholestasis with pericellular fibrosis. Sofosbuvir, an HCV polymerase inhibitor (400 mg/day), and daclatasvir, an HCV NS5A replication complex inhibitor (60 mg/day), were co‐administered for 24 weeks. Within 4 weeks of initiating treatment, serum HCV RNA levels became undetectable and liver biochemistries normalized with concomitant resolution of ascites. The patient achieved a sustained virological response with undetectable HCV RNA at 9 months posttreatment. During and following treatment, the daily dose and blood level of tacrolimus remained stable and unchanged. The rapid and sustained suppression of HCV replication in this liver transplant recipient provides great promise for the use of combination oral antiviral regimens in other immunosuppressed and interferon refractory HCV patients.

The pharmacokinetic data support coadministration of daclatasvir with atazanavir/ritonavir, efavirenz and/or tenofovir. A Phase III study in HIV-HCV coinfection has commenced using the described dose modifications.

[structure--see text] A semisynthetic route to epothilone cyclopropanes from epothilones A and B is described. Of significance, the deoxygenation of the 12, 13-epoxide to give the corresponding olefin was achieved with high efficiency. The title compounds (8, 9) were active in both tubulin polymerization and cytotoxicity assays, which is in direct contrast to a previously published report. These results provide further evidence that the role of the 12,13-epoxide of epothilones is largely conformational and argue against some of the current pharmacophore models.

A double-blind, placebo-controlled, multiple oral dose escalation study was conducted to investigate the pharmacokinetics, safety, and tolerability of entecavir in healthy subjects. Eight subjects were assigned to each of the 3 dose panels (0.1 mg, 0.5 mg, and 1 mg or matched placebo once daily for 14 days). Blood and urine samples were collected for pharmacokinetic analyses. Entecavir was rapidly absorbed, with peak plasma concentration occurring within 1 hour of dosing. Steady-state plasma concentrations of entecavir were achieved by 10 days following the initial dose. At steady state, the mean area under the plasma concentration-time curve over 1 dosing interval, increased approximately proportional to dose. Entecavir had a mean terminal half-life ranging from 128 to 149 hours and an effective half-life of approximately 24 hours. Elimination was predominantly through renal excretion, with mean urinary recovery ranging from 62% to 73%. Entecavir was safe and well tolerated when administered at doses ranging from 0.1 mg to 1 mg/d for 14 days.

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The lithistid sponge Scleritoderma nodosum contains a new cyclic peptide, scleritodermin A (1), the structure of which incorporates l-proline, l-serine, and keto-allo-isoleucine units as well as a novel conjugated thiazole moiety (ACT) and O-methyl-N-sulfoserine. Scleritodermin A (1) inhibited tubulin polymerization and showed significant in vitro cytotoxicity against human tumor cell lines.