Dennis Hernandez

Daclatasvir plus Sofosbuvir for Previously Treated or Untreated Chronic HCV Infection

BACKGROUND All-oral combination therapy is desirable for patients with chronic hepatitis C virus (HCV) infection. We evaluated daclatasvir (an HCV NS5A replication complex inhibitor) plus sofosbuvir (a nucleotide analogue HCV NS5B polymerase inhibitor) in patients infected with HCV genotype 1, 2, or 3. METHODS In this open-label study, we initially randomly assigned 44 previously untreated patients with HCV genotype 1 infection and 44 patients infected with HCV genotype 2 or 3 to daclatasvir at a dose of 60 mg orally once daily plus sofosbuvir at a dose of 400 mg orally once daily, with or without ribavirin, for 24 weeks. The study was expanded to include 123 additional patients with genotype 1 infection who were randomly assigned to daclatasvir plus sofosbuvir, with or without ribavirin, for 12 weeks (82 previously untreated patients) or 24 weeks (41 patients who had previous virologic failure with telaprevir or boceprevir plus peginterferon alfa-ribavirin). The primary end point was a sustained virologic response (an HCV RNA level of <25 IU per milliliter) at week 12 after the end of therapy. RESULTS Overall, 211 patients received treatment. Among patients with genotype 1 infection, 98% of 126 previously untreated patients and 98% of 41 patients who did not have a sustained virologic response with HCV protease inhibitors had a sustained virologic response at week 12 after the end of therapy. A total of 92% of 26 patients with genotype 2 infection and 89% of 18 patients with genotype 3 infection had a sustained virologic response at week 12. High rates of sustained virologic response at week 12 were observed among patients with HCV subtypes 1a and 1b (98% and 100%, respectively) and those with CC and non-CC IL28B genotypes (93% and 98%, respectively), as well as among patients who received ribavirin and those who did not (94% and 98%, respectively). The most common adverse events were fatigue, headache, and nausea. CONCLUSIONS Once-daily oral daclatasvir plus sofosbuvir was associated with high rates of sustained virologic response among patients infected with HCV genotype 1, 2, or 3, including patients with no response to prior therapy with telaprevir or boceprevir. (Funded by Bristol-Myers Squibb and Pharmasset (Gilead); A1444040 ClinicalTrials.gov number, NCT01359644.).

Efficacies of Entecavir against Lamivudine-Resistant Hepatitis B Virus Replication and Recombinant Polymerases In Vitro

ABSTRACT Entecavir (ETV) is a potent and selective inhibitor of hepatitis B virus (HBV) replication in vitro and in vivo that is currently in clinical trials for the treatment of chronic HBV infections. A major limitation of the current HBV antiviral therapy, lamivudine (3TC), is the emergence of drug-resistant HBV in a majority of treated patients due to specific mutations in the nucleotide binding site of HBV DNA polymerase (HBV Pol). To determine the effects of 3TC resistance mutations on inhibition by ETV triphosphate (ETV-TP), a series of in vitro studies were performed. The inhibition of wild-type and 3TC-resistant HBV Pol by ETV-TP was measured using recombinant HBV nucleocapsids, and compared to that of 3TC-TP. These enzyme inhibition studies demonstrated that ETV-TP is a highly potent inhibitor of wild-type HBV Pol and is 100- to 300-fold more potent than 3TC-TP against 3TC-resistant HBV Pol. Cell culture assays were used to gauge the potential for antiviral cross-resistance of 3TC-resistant mutants to ETV. Results demonstrated that ETV inhibited the replication of 3TC-resistant HBV, but 20- to 30-fold higher concentrations were required. To gain further perspective regarding the potential therapeutic use of ETV, its phosphorylation was examined in hepatoma cells treated with extracellular concentrations representative of drug levels in plasma in ETV-treated patients. At these concentrations, intracellular ETV-TP accumulated to levels expected to inhibit the enzyme activity of both wild-type and 3TC-resistant HBV Pol. These findings are predictive of potent antiviral activity of ETV against both wild-type and 3TC-resistant HBV.

Preclinical Profile and Characterization of the Hepatitis C Virus NS3 Protease Inhibitor Asunaprevir (BMS-650032)

ABSTRACT Asunaprevir (ASV; BMS-650032) is a hepatitis C virus (HCV) NS3 protease inhibitor that has demonstrated efficacy in patients chronically infected with HCV genotype 1 when combined with alfa interferon and/or the NS5A replication complex inhibitor daclatasvir. ASV competitively binds to the NS3/4A protease complex, with Ki values of 0.4 and 0.24 nM against recombinant enzymes representing genotypes 1a (H77) and 1b (J4L6S), respectively. Selectivity was demonstrated by the absence of any significant activity against the closely related GB virus-B NS3 protease and a panel of human serine or cysteine proteases. In cell culture, ASV inhibited replication of HCV replicons representing genotypes 1 and 4, with 50% effective concentrations (EC50s) ranging from 1 to 4 nM, and had weaker activity against genotypes 2 and 3 (EC50, 67 to 1,162 nM). Selectivity was again demonstrated by the absence of activity (EC50, >12 μM) against a panel of other RNA viruses. ASV exhibited additive or synergistic activity in combination studies with alfa interferon, ribavirin, and/or inhibitors specifically targeting NS5A or NS5B. Plasma and tissue exposures in vivo in several animal species indicated that ASV displayed a hepatotropic disposition (liver-to-plasma ratios ranging from 40- to 359-fold across species). Twenty-four hours postdose, liver exposures across all species tested were ≥110-fold above the inhibitor EC50s observed with HCV genotype-1 replicons. Based on these virologic and exposure properties, ASV holds promise for future utility in a combination with other anti-HCV agents in the treatment of HCV-infected patients.

Daclatasvir for previously untreated chronic hepatitis C genotype-1 infection: a randomised, parallel-group, double-blind, placebo-controlled, dose-finding, phase 2a trial

BACKGROUND Several direct-acting antivirals for chronic hepatitis C virus (HCV) infection are available, but they are limited by tolerability and dosing schedules. Once-daily daclatasvir, a potent NS5A replication complex inhibitor, was generally well tolerated in phase 1 studies. We assessed daclatasvir in combination with pegylated interferon (peginterferon) and ribavirin for chronic HCV. METHODS In this double-blind, parallel-group, dose-finding, phase 2a study, treatment-naive patients with HCV genotype-1 infection (without cirrhosis) from 14 centres in the USA and France were randomly assigned (1:1:1:1) to receive peginterferon alfa-2a (180 μg per week) and ribavirin (1000-1200 mg daily) plus placebo or 3 mg, 10 mg, or 60 mg of daclatasvir taken once daily, for 48 weeks. The primary efficacy endpoint was undetectable HCV RNA at 4 weeks and 12 weeks after start of treatment (extended rapid virological response, eRVR). Analysis was of all participants who received one dose of study drug. We used descriptive analyses to compare results. This study is registered with ClinicalTrials.gov, number NCT00874770. FINDINGS 48 patients were randomly assigned (12 per group); all received at least one dose of study drug. 15 patients discontinued treatment before week 48. Five of 12 patients (42%, 80% CI 22-64%) who received 3 mg daclatasvir achieved eRVR, compared with ten of 12 (83%, 61-96%) who received 10 mg daclatasvir, nine of 12 (75%, 53-90%) who received 60 mg daclatasvir, and one of 12 (8%, 1-29%) who received placebo. Adverse events and discontinuations as a result of adverse events occurred with similar frequency across groups. INTERPRETATION Daclatasvir seems to be a potent NS5A replication complex inhibitor that increases the antiviral potency of peginterferon and ribavirin. Our findings support the further development of regimens containing 60 mg daclatasvir for the treatment of chronic genotype-1 HCV infection. FUNDING Bristol-Myers Squibb.

Characterization of virologic escape in hepatitis C virus genotype 1b patients treated with the direct-acting antivirals daclatasvir and asunaprevir.

BACKGROUND & AIMS Daclatasvir and asunaprevir are NS5A and NS3 protease-targeted antivirals currently under development for treatment of chronic hepatitis C virus infection. Clinical data on baseline and on-treatment correlates of drug resistance and response to these agents are currently limited. METHODS Hepatitis C virus genotype 1b Japanese patients (prior null responders to PegIFN-α/RBV [n=21] or PegIFN-α/RBV ineligible or intolerant [n=22]) were administered daclatasvir/asunaprevir for 24 weeks during a phase 2a open-label study. Genotypic and phenotypic analyses of NS3 and NS5A substitutions were performed at baseline, after virologic failure, and post-treatment through follow-up week 36. RESULTS There were three viral breakthroughs and four relapsers. Baseline NS3 polymorphisms (T54S, Q80L, V170M) at amino acid positions previously associated with low-level resistance (<9-fold) to select NS3 protease inhibitors were detected in four null responders and three ineligibles, but were not associated with virologic failure. Baseline NS5A polymorphisms (L28M, L31M, Y93H) associated with daclatasvir resistance (<25-fold) were detected in five null responders and six ineligibles. All three viral breakthroughs and 2/4 relapsers carried a baseline NS5A-Y93H polymorphism. NS3 and NS5A resistance-associated variants were detected together (NS3-D168A/V, NS5A-L31M/V-Y93H) after virologic failure. Generally, daclatasvir-resistant substitutions persisted through 48weeks post-treatment, whereas asunaprevir-resistant substitutions were no longer detectable. Overall, 5/10 patients with baseline NS5A-Y93H experienced virologic failure, while 5/10 achieved a sustained virologic response. CONCLUSIONS The potential association of a pre-existing NS5A-Y93H polymorphism with virologic failure on daclatasvir/asunaprevir combination treatment will be examined in larger studies. The persistence of treatment-emergent daclatasvir- and asunaprevir-resistant substitutions will require assessment in longer-term follow-up studies.

Resistance analysis of hepatitis C virus genotype 1 prior treatment null responders receiving daclatasvir and asunaprevir

In a sentinel cohort, hepatitis C virus (HCV) patients (primarily genotype [GT] 1a) were treated with daclatasvir (NS5A inhibitor) and asunaprevir (NS3 protease inhibitor). Preexistence, emergence, and persistence of resistance variants in patients who failed this treatment are described. HCV‐infected null responders received daclatasvir (60 mg once daily) and asunaprevir (600 mg twice daily) alone (Group A, 11 patients) or with peginterferon alfa‐2a and ribavirin (Group B, 10 patients) for 24 weeks. Resistance testing was performed on baseline samples and samples with HCV RNA ≥1,000 IU/mL at Week 1 through posttreatment Week 48. Resistance substitution susceptibility to inhibition by asunaprevir and daclatasvir was assessed using HCV replicon assays. In Group A, six GT1a patients experiencing viral breakthrough and one GT1a patient who relapsed had detectable NS5A (Q30E/R, L31V/M, Y93C/N) and NS3 (R155K, D168A/E/V/Y) resistance‐associated variants at failure. Two of six viral breakthrough patients achieved SVR48 after treatment intensification with peginterferon alfa‐2a and ribavirin. For 2/4 viral breakthrough patients not responding to treatment intensification, NS3 resistance variants changed (D168Y to D168T; R155K to V36M‐R155K). At posttreatment Week 48, daclatasvir‐resistant variants persisted while asunaprevir‐resistant variants were generally replaced by wild‐type sequences. The NS3 sequence remained unchanged in the one patient with NS3‐R155K at baseline, relapse, and posttreatment Week 48. In Group B, no viral breakthrough was observed. Conclusion: The treatment failure of daclatasvir and asunaprevir in HCV GT1a patients was associated with both NS5A and NS3 resistance variants in prior null responders. NS5A resistance variants persisted while NS3 resistance variants generally decayed, suggesting a higher relative fitness of NS5A variants. (Hepatology 2013;53:902–911)

Daclatasvir plus peginterferon alfa and ribavirin for treatment-naive chronic hepatitis C genotype 1 or 4 infection: a randomised study

Objective To evaluate the safety and efficacy of daclatasvir, an HCV NS5A inhibitor with pangenotypic activity, administered with peginterferon-alfa-2a/ribavirin. Design In this Phase 2b double-blind, placebo-controlled study, treatment-naive adults with HCV genotype 1 (N=365) or 4 (N=30) infection were randomly assigned (2:2:1) to daclatasvir 20 mg or 60 mg, or placebo once daily plus weekly peginterferon-alfa-2a and twice-daily ribavirin. Daclatasvir recipients achieving protocol-defined response (PDR; HCV-RNA<lower limit of quantitation at Week 4 and undetectable at Week 10) were rerandomised at Week 12 to continue daclatasvir/peginterferon-alfa-2a/ribavirin for 24 weeks total duration or to placebo/peginterferon-alfa-2a/ribavirin for another 12 weeks. Patients without PDR and placebo patients continued peginterferon-alfa/ribavirin through Week 48. Primary efficacy endpoints were undetectable HCV-RNA at Weeks 4 and 12 (extended rapid virologic response, eRVR) and at 24 weeks post-treatment (sustained virologic response, SVR24) among genotype 1-infected patients. Results Overall, eRVR was achieved by 54.4% (80/147) of genotype 1-infected patients receiving daclatasvir 20 mg, 54.1% (79/146) receiving 60 mg versus 13.9% (10/72) receiving placebo. SVR24 was achieved among 87 (59.2%), 87 (59.6%), and 27 (37.5%) patients in these groups, respectively. Higher proportions of genotype 4-infected patients receiving daclatasvir 20 mg (66.7%; 8/12) or 60 mg (100.0%; 12/12) achieved SVR24 versus placebo (50.0%; 3/6). A majority of daclatasvir-treated patients achieved PDR and experienced less virologic failure and higher SVR24 rates with a shortened 24-week treatment duration. Adverse events occurred with similar frequency across all treatment groups. Conclusions The combination of daclatasvir/peginterferon-alfa/ribavirin was generally well tolerated and achieved higher SVR24 rates compared with placebo/peginterferon-alfa/ribavirin among patients infected with HCV genotype 1 or 4. Trial registration number NCT01125189.

Resistance Analysis of the Hepatitis C Virus NS3 Protease Inhibitor Asunaprevir

ABSTRACT Asunaprevir (BMS-650032) is a potent hepatitis C virus (HCV) NS3 protease inhibitor demonstrating efficacy in alfa interferon-sparing, direct-acting antiviral dual-combination regimens (together with the NS5A replication complex inhibitor daclatasvir) in patients chronically infected with HCV genotype 1b. Here, we describe a comprehensive in vitro genotypic and phenotypic analysis of asunaprevir-associated resistance against genotypes 1a and 1b using HCV replicons and patient samples obtained from clinical studies of short-term asunaprevir monotherapy. During genotype 1a resistance selection using HCV replicons, the primary NS3 protease substitutions identified were R155K, D168G, and I170T, which conferred low- to moderate-level asunaprevir resistance (5- to 21-fold) in transient-transfection susceptibility assays. For genotype 1b, a higher level of asunaprevir-associated resistance was observed at the same selection pressures, ranging from 170- to 400-fold relative to the wild-type control. The primary NS3 protease substitutions identified occurred predominantly at amino acid residue D168 (D168A/G/H/V/Y) and were associated with high-level asunaprevir resistance (16- to 280-fold) and impaired replication capacity. In asunaprevir single-ascending-dose and 3-day multiple-ascending-dose studies in HCV genotype 1a- or 1b-infected patients, the predominant pre-existing NS3 baseline polymorphism was NS3-Q80K. This substitution impacted initial virologic response rates in a single-ascending-dose study, but its effects after multiple doses were more ambiguous. Interestingly, for patient NS3 protease sequences containing Q80 and those containing K80, susceptibilities to asunaprevir were comparable when tested in an enzyme assay. No resistance-associated variants emerged in these clinical studies that significantly impacted susceptibility to asunaprevir. Importantly, asunaprevir-resistant replicons remained susceptible to an NS5A replication complex inhibitor, consistent with a role for asunaprevir in combination therapies.

The Discovery of Asunaprevir (BMS-650032), An Orally Efficacious NS3 Protease Inhibitor for the Treatment of Hepatitis C Virus Infection

The discovery of asunaprevir (BMS-650032, 24) is described. This tripeptidic acylsulfonamide inhibitor of the NS3/4A enzyme is currently in phase III clinical trials for the treatment of hepatitis C virus infection. The discovery of 24 was enabled by employing an isolated rabbit heart model to screen for the cardiovascular (CV) liabilities (changes to HR and SNRT) that were responsible for the discontinuation of an earlier lead from this chemical series, BMS-605339 (1), from clinical trials. The structure-activity relationships (SARs) developed with respect to CV effects established that small structural changes to the P2* subsite of the molecule had a significant impact on the CV profile of a given compound. The antiviral activity, preclincial PK profile, and toxicology studies in rat and dog supported clinical development of BMS-650032 (24).

Natural prevalence of NS5A polymorphisms in subjects infected with hepatitis C virus genotype 3 and their effects on the antiviral activity of NS5A inhibitors

BACKGROUND Hepatitis C virus (HCV) NS5A replication complex inhibitors (RCIs) have been shown to exhibit picomolar antiviral activity against genotype 1 (GT1) in vitro. This has translated into rapid and robust declines in HCV RNA in GT1 patients. Less is known about the susceptibility of other genotypes such as GT3 to inhibition by NS5A RCIs. OBJECTIVES To detect and phenotype naturally occurring HCVGT3 NS5A polymorphisms against two NS5A RCIs (daclatasvir [DCV] and GS-5885) currently in clinical development. STUDY DESIGN The NS5A region from 96 HCV GT3 treatment-naive patients spanning North America, Europe and Australia was determined. RESULTS Phylogenetic analysis revealed a broad distribution with no significant geographic clustering. GT1 DCV resistance-associated variants (RAVs) were observed in GT3 subjects; variants (and their frequencies) included 28M/V (1%), 30A/K/S/T/V (10%), 31L/M (1%), E92A (1%) and Y93H (8.3%). A consensus sequence was used to generate a JFH1/3a-NS5A hybrid replicon and employed to assess susceptibility to NS5A RCIs. Against JFH1/3a-NS5A, DCV was more potent (EC(50) = 0.52 nM) than GS-5885 (EC(50) = 141 nM). DCV sensitivity was increased against JFH1/3a-NS5A-M28V (EC50 = 0.006 nM), A30V (EC(50) = 0.012 nM), and E92A (EC(50) = 0.004 nM) while the NS5A-A30K and -Y93H variants exhibited reduced sensitivity to DCV (EC50 values of 23 nM and 1120 nM, respectively) and to GS-5885 (EC50 values of 1770 nM and 4300 nM, respectively). CONCLUSIONS Substitutions conferring resistance to NS5A RCIs pre-existed in treatment-naive patients infected with HCV GT3. The effectiveness of these NS5A RCIs to exert efficacy in the clinic may depend on which inhibitor is used in combination with other antivirals.