rg-7128 and Hepatitis-C--Chronic

Mericitabine (RG7128), an orally administered prodrug of PSI-6130, is the most clinically advanced nucleoside analogue inhibitor of the RNA-dependent RNA polymerase (RdRp) of HCV. This review describes what has been learnt so far about the resistance profile of mericitabine. A serine to threonine substitution at position 282 (S282T) of the RdRp that reduces its replication capacity to approximately 15% of wild-type is the only variant that has been consistently generated in serial in vitro passage experiments. To date, no evidence of genotypic resistance to mericitabine has been detected by population or clonal sequence analysis in any baseline or on-treatment samples collected from >600 patients enrolled in Phase I/II trials of mericitabine administered as monotherapy, in combination with pegylated interferon/ribavirin, or in combination with the protease inhibitor, danoprevir, for 14 days in the proof-of-concept study of interferon-free therapy.

Topics: Antiviral Agents; Clinical Trials, Phase I as Topic; Clinical Trials, Phase II as Topic; Deoxycytidine; Drug Resistance, Viral; Drug Therapy, Combination; Hepacivirus; Hepatitis C, Chronic; Humans; RNA-Dependent RNA Polymerase; Treatment Outcome

Several directly acting and host targeting antivirals that inhibit hepatitis C virus replication have entered clinical trials. Among the most advanced of these are RG7128, an inhibitor of the NS5B polymerase; BMS-790052, an inhibitor of NS5A; and alisporivir, an inhibitor of human cyclophilins. These agents have potent antiviral activity in chronic HCV patients, act additively or synergistically with inhibitors of the HCV NS3/4A protease, and improve the rate of virologic response produced by traditional pegylated interferon plus ribavirin therapy. No cross resistance has been observed; moreover, nucleoside NS5B and cyclophilin inhibitors appear to suppress resistance to non-nucleoside NS5B and NS3/4A inhibitors. Several recent reports of virologic responses produced by combinations of agents that inhibit HCV replication in the absence of interferon provide optimism that eradication of HCV will be possible without interferon in the future.

Topics: Animals; Antiviral Agents; Carbamates; Cyclosporine; Deoxycytidine; Hepacivirus; Hepatitis C, Chronic; Humans; Imidazoles; Pyrrolidines; Valine; Virus Replication

Hepatitis C infection has evolved in the past quarter century from a newly recognized entity without a known pathogen (non-A, non-B hepatitis) to one of the world's most prevalent causes of liver disease, an important source for hepatocellular carcinoma, and the major indication for liver transplantation. It is caused by a virus with a complex replication cycle that occurs in multiple genotypes, of which the four most prevalent (1, 2, 3, and 4) exhibit differences in clinical behavior and responses to therapy. Chronic hepatitis C virus (HCV) in particular has evolved from a disease with no known treatment to one with several primary treatment options, none of which is uniformly effective, and a growing list of secondary treatment options for those who have failed to respond to, or relapsed after initial therapy. As treatment is often associated with significant side effects, it is now a disease that presents clinicians with multiple important decisions: whom to treat, when and with what to treat them initially, and how to manage patients who have failed during initial therapy to achieve a sustained virological response, the gold standard of effective therapy. This review examines each of these important decisions, presenting evidence to help guide clinicians in their choices. The decisions are addressed sequentially as they arise during the initial evaluation and subsequent treatment of a typical, newly recognized patient with chronic HCV, and the considerations facing the clinician when the patient has failed to achieve an SVR.

Topics: Alcohol Drinking; Antiviral Agents; Biopsy; Decision Making; Deoxycytidine; Disease Management; Disease Progression; Drug Therapy, Combination; Genotype; Hepacivirus; Hepatitis C, Chronic; Humans; Interferon alpha-2; Interferon-alpha; Liver; Liver Cirrhosis; Liver Function Tests; Male; Middle Aged; Obesity; Polyethylene Glycols; Practice Patterns, Physicians'; Recombinant Proteins; Retreatment; Ribavirin; RNA, Viral; Treatment Failure; Viral Load; Virus Replication

Setrobuvir is a direct-acting antiviral (DAA) non-nucleoside inhibitor of hepatitis C virus (HCV) polymerase. This study examined interferon-free combinations containing setrobuvir, a ritonavir-boosted protease inhibitor (danoprevir/r) and ribavirin, with/without the nucleoside inhibitor mericitabine in HCV genotype (G)1 patients.. Non-cirrhotic treatment-naïve patients (N = 110) were randomized to five groups. Three groups received a 14-day mericitabine/ribavirin lead-in followed by treatment with 3 DAAs (setrobuvir, danoprevir/r, mericitabine) plus ribavirin for 12 weeks (Group A: G1a; D: G1b) or 24 weeks (B: G1a), and two groups received 2 DAAs (setrobuvir, danoprevir/r) plus ribavirin for 12 weeks (E: G1b) or 24 weeks (C: G1a). Efficacy was defined as sustained virological response (HCV RNA <25 IU/ml after 12 weeks' follow-up, SVR12).. Two groups met predefined futility criteria for breakthrough (C) or relapse (A) and were discontinued. SVR12 rates were 42.9% (3/7) and 74.1% (20/27) in G1a patients in Groups A and B, respectively, and 95.7% (22/23) and 68.2% (15/22) in G1b patients in Groups D and E respectively. All G1a patients assigned to 24 weeks of treatment who experienced a decrease in HCV RNA of ≥2.3 log10 IU by the end of the lead-in period (n = 28) achieved SVR12. Overall, treatment was well tolerated and most adverse events were mild to moderate. No major safety signals were identified.. An interferon-free setrobuvir-based regimen (3 DAAs plus ribavirin) is safe and effective in treatment-naïve G1 patients.

Topics: Adult; Antiviral Agents; Australia; Benzothiadiazines; Cyclopropanes; Deoxycytidine; Drug Therapy, Combination; Europe; Female; Genotype; Hepacivirus; Hepatitis C, Chronic; Humans; Interferons; Isoindoles; Lactams; Lactams, Macrocyclic; Male; Middle Aged; New Zealand; Phenotype; Proline; Quinolones; Remission Induction; Ribavirin; RNA, Viral; Sulfonamides; Time Factors; Treatment Outcome; United States; Viral Load

Modelling HCV RNA decline kinetics under therapy has proven useful for characterizing treatment effectiveness.. Here we model HCV viral kinetics (VK) in 72 patients given a combination of danoprevir, a protease inhibitor, and mericitabine, a nucleoside polymerase inhibitor, for 14 days in the INFORM-1 trial. A biphasic VK model with time-varying danoprevir and mericitabine effectiveness and Bliss independence for characterizing the interaction between both drugs provided the best fit to the VK data.. The average final antiviral effectiveness of the drug combination varied between 0.998 for 100 mg three times daily of danoprevir and 500 mg twice daily of mericitabine and 0.9998 for 600 mg twice daily of danoprevir and 1,000 mg twice daily of mericitabine. Using the individual parameters estimated from the VK data collected over 2 weeks, we were not able to reproduce the low sustained virological response rates obtained in a more recent study where patients were treated with a combination of mericitabine and ritonavir-boosted danoprevir for 24 weeks.. This suggests that drug-resistant viruses emerge after 2 weeks of treatment and that longer studies are necessary to provide accurate predictions of longer treatment outcomes.

Topics: Antiviral Agents; Cyclopropanes; Deoxycytidine; Dose-Response Relationship, Drug; Drug Interactions; Drug Therapy, Combination; Genotype; Hepacivirus; Hepatitis C, Chronic; Humans; Isoindoles; Lactams; Lactams, Macrocyclic; Models, Biological; Proline; RNA, Viral; Sulfonamides; Viral Load

Most patients with chronic hepatitis C virus (HCV) genotype 1 infection who have had a previous null response (<2-log10 reduction in HCV RNA by treatment week 12) to peginterferon/ribavirin (PegIFN/RBV) do not achieve a sustained virological response (SVR) when re-treated with a first-generation HCV protease inhibitor (PI) administered in combination with PegIFN/RBV. We studied the incremental benefits associated with adding mericitabine (nucleoside analog inhibitor of HCV polymerase) to PI plus PegIFN alfa-2a/RBV-based therapy in two double-blind randomized multicenter phase 2 trials (with boceprevir in DYNAMO 1, and with telaprevir in DYNAMO 2). The primary endpoint in both trials was SVR, defined as HCV RNA <25 IU/mL 12 weeks after the end of treatment (SVR12). Overall, the addition of mericitabine to PI plus PegIFN alfa-2a/RBV therapy resulted in SVR12 rates of 60-70% in DYNAMO 1 and of 71-96% in DYNAMO 2. SVR12 rates were similar in patients infected with HCV genotype 1a and 1b in both trials. The placebo control arms in both studies were stopped because of high rates of virological failure. Numerically lower relapse rates were associated with longer treatment with mericitabine (24 versus 12 weeks), telaprevir-containing regimens, and regimens that included 48 weeks of PegIFN alfa-2a/RBV therapy. No mericitabine resistance mutations were identified in any patient in either trial. The addition of mericitabine did not add to the safety burden associated with either telaprevir or boceprevir-based regimens. These studies demonstrate increased SVR rates and reduced relapse rates in difficult-to-treat patients when a nucleoside polymerase inhibitor with intermediate antiviral potency is added to regimens containing a first-generation PI.. ClinicalTrials.gov NCT01482403 and ClinicalTrials.gov NCT01482390.

Topics: Adult; Antibodies, Viral; Antimetabolites; Antiviral Agents; Deoxycytidine; Double-Blind Method; Drug Administration Schedule; Drug Therapy, Combination; Female; Genotype; Hepacivirus; Hepatitis C, Chronic; Humans; Interferon-alpha; Male; Middle Aged; Oligopeptides; Polyethylene Glycols; Proline; Protease Inhibitors; Recombinant Proteins; Ribavirin; RNA, Viral; Treatment Outcome

Viral kinetic models have proven useful to characterize treatment effectiveness during HCV therapy with interferon (IFN) or with direct-acting antivirals.. We use a pharmacokinetic/viral kinetic (PK/VK) model to describe HCV RNA kinetics during treatment with danoprevir, a protease inhibitor. In a Phase I study, danoprevir monotherapy was administered for 14 days in ascending doses ranging from 200 to 600 mg per day to 40 patients of whom 32 were treatment-naive and 8 were non-responders to prior pegylated IFN-α/ribavirin treatment.. In all patients, a biphasic decline of HCV RNA during therapy was observed. A two-compartment PK model and a VK model that considered treatment effectiveness to vary with the predicted danoprevir concentration inside the second compartment provided a good fit to the viral load data. A time-varying effectiveness model was also used to fit the viral load data. The antiviral effectiveness increased in a dose-dependent manner, with a 14-day time-averaged effectiveness of 0.95 at the lowest dose (100 mg twice daily) and 0.99 at the highest dose (200 mg three times daily). Prior IFN non-responders exhibited a 14-day time-averaged effectiveness of 0.98 (300 mg twice daily). The second phase decline showed two different behaviours, with 30% of patients exhibiting a rapid decline of HCV RNA, comparable to that seen with other protease inhibitors (>0.3 day(-1)), whereas the viral decline was slower in the other patients.. Our results are consistent with the modest SVR rates from the INFORM-SVR study where patients were treated with a combination of mericitabine and ritonavir-boosted danoprevir.

Topics: Antiviral Agents; Cyclopropanes; Deoxycytidine; Dose-Response Relationship, Drug; Drug Therapy, Combination; Hepacivirus; Hepatitis C, Chronic; Humans; Interferon-alpha; Isoindoles; Lactams; Lactams, Macrocyclic; Models, Theoretical; Polyethylene Glycols; Proline; Protease Inhibitors; Recombinant Proteins; Ribavirin; Sulfonamides; Treatment Outcome; Viral Load; Viral Nonstructural Proteins

Resistance to mericitabine (prodrug of HCV NS5B polymerase inhibitor PSI-6130) is rare and conferred by the NS5B S282T mutation.. Serum HCV RNA from patients who experienced viral breakthrough, partial response, or nonresponse in 2 clinical trials in which patients received mericitabine plus peginterferon alfa-2a (40KD)/ribavirin were analyzed by population and clonal sequence analysis as well as phenotypic assay for assessment of in vivo mericitabine resistance.. Among 405 patients treated with mericitabine plus peginterferon alfa-2a/ribavirin in PROPEL and JUMP-C, virologic breakthrough or nonresponse were not observed; 12 patients experienced a partial response. The NS5B S282T resistance mutation was not observed in any patient. A number of treatment-associated NS5B changes were observed and characterized. A novel double mutant (L159F/L320F) with impaired replication capacity was detected in one HCV genotype 1b-infected patient. Introduction of double mutant L159F/L320F into genotype 1a (H77) and 1b (Con-1) replicons, respectively, increased the EC50 for mericitabine by 3.1- and 5.5-fold and the EC90 by 3.1- and 8.9-fold. The double mutant also decreased susceptibility to sofosbuvir (GS-7977) and GS-938 but not setrobuvir, relative to wild-type.. A novel and replication-deficient double mutation (L159F/L320F) confers low-level resistance to mericitabine and cross-resistance to both sofosbuvir and GS-938.. NCT00869661, NCT01057667.

Topics: Antiviral Agents; Deoxycytidine; Drug Resistance, Viral; Drug Therapy, Combination; Genotype; Hepacivirus; Hepatitis C, Chronic; Humans; Interferon-alpha; Mutation; Polyethylene Glycols; Recombinant Proteins; Replicon; Ribavirin; RNA, Viral; Sofosbuvir; Uridine Monophosphate; Viral Nonstructural Proteins

Baseline and posttreatment samples from hepatitis C virus (HCV) genotype (GT) 1-infected patients who received a combination of danoprevir and mericitabine from a phase II clinical study (INFORM-SVR) were analyzed. In addition to resistance monitoring, sequencing and phenotypic assays were combined with statistical analysis to identify potential novel amino acid substitutions associated with treatment outcome. The NS5B S282T substitution associated with mericitabine resistance was identified in 2/30 viral breakthrough patients and was replaced by wild-type viruses after cessation of drug treatment (during follow-up). The NS3 R155K substitution associated with danoprevir resistance was also observed in these 2 patients. All 69 GT 1a-infected patients who experienced viral breakthrough on treatment or relapsed during follow-up (relapsers) developed NS3 R155K. Among GT 1b-infected patients, substitutions at the danoprevir resistance locus NS3 D168 were observed in 15/20 subjects, whereas substitutions at the danoprevir resistance locus NS3 R155 were observed in 5/20 subjects. Interestingly, the baseline polymorphism NS5B Q47H was more prevalent in GT 1a-infected patients who achieved a sustained virologic response at follow-up week 24 (SVR24) than in non-SVR24 patients (2/13 versus 0/72), and a postbaseline NS3 S122G substitution was more prevalent in GT 1a-infected patients with viral breakthrough than in relapsers (4/22 versus 0/47). Neither substitution conferred resistance to danoprevir or mericitabine, but the substitutions reduced (NS5B Q47H) or improved (NS3 S122G) replication capacity by 2- to 4-fold. The NS5B S282T mericitabine-resistant variant was rare and did not persist once drug was discontinued. NS5B Q47H and NS3 S122G are two newly identified substitutions that affected replication capacity and were enriched in distinct treatment response groups. (This study has been registered at ClinicalTrials.gov under registration no. NCT01278134.).

Topics: Adult; Amino Acid Substitution; Antiviral Agents; Base Sequence; Cyclopropanes; Deoxycytidine; DNA Replication; Drug Resistance, Viral; Drug Therapy, Combination; Female; Genotype; Hepacivirus; Hepatitis C, Chronic; Humans; Isoindoles; Lactams; Lactams, Macrocyclic; Male; Middle Aged; Molecular Sequence Data; Mutation; Phenotype; Proline; RNA, Viral; Sequence Analysis, DNA; Sulfonamides; Viral Nonstructural Proteins

Mericitabine is a nucleoside analog polymerase inhibitor of hepatitis C virus (HCV). Treatment-naïve HCV genotype 1 or 4 patients were randomized to double-blind treatment with oral mericitabine at a dosage of 500 mg twice-daily (BID) for 12 weeks (A), 1,000 mg BID for 8 (B) or 12 weeks (C and D), or placebo BID for 12 weeks (E). All patients received pegylated interferon alpha-2a (Peg-IFNα-2a; 40 kD)/ribavirin (RBV) at standard doses for 24 or 48 weeks during and after mericitabine/placebo therapy. Patients in arms A-C who maintained a virologic response (VR) (HCV RNA <15 IU/mL) from weeks 4 to 22 stopped all treatment at week 24; all other patients (arms A-E) continued Peg-IFNα-2a/RBV to complete 48 weeks. The primary outcome was sustained VR (SVR) (HCV RNA <15 IU/mL after 24 weeks of untreated follow-up; SVR-24). VR rates were higher in arms A-D than in arm E at weeks 4 and 12 overall, in patients with and without cirrhosis and in patients with CC and non-CC IL28B genotypes. However, the overall SVR-24 rate in arms D (50.6%) and E (placebo, 51.2%) was similar and those in the response-guided therapy arms A, B, and C were lower (48.8%, 42.0%, and 32.9%, respectively). No viral breakthrough or mericitabine-resistance mutations (S282T) were observed during mericitabine therapy.. Treatment with mericitabine plus Peg-IFNα-2a/RBV for 8 or 12 weeks provided potent suppression of HCV RNA, was well tolerated, and did not select resistant variants, but did not increase SVR rates, compared to placebo. IFN-free and IFN-containing trials of mericitabine of longer treatment duration are ongoing.

Topics: Adolescent; Adult; Aged; Deoxycytidine; Dose-Response Relationship, Drug; Double-Blind Method; Drug Therapy, Combination; Female; Genotype; Hepacivirus; Hepatitis C, Chronic; Humans; Interferon-alpha; Interferons; Interleukins; Male; Middle Aged; Polyethylene Glycols; Recombinant Proteins; Ribavirin; RNA, Viral; Treatment Outcome; Young Adult

Mericitabine is a selective nucleoside analog inhibitor of the hepatitis C virus (HCV) NS5B RNA-dependent RNA polymerase, with activity across all HCV genotypes. Treatment-naïve patients infected with HCV genotype 1 or 4 were randomized to 24 weeks of double-blind treatment with either mericitabine 1,000 mg (N = 81) or placebo (N = 85) twice-daily (BID) in combination with pegylated interferon alpha-2a (Peg-IFNα-2a)/ribavirin (RBV). Patients randomized to mericitabine with HCV RNA <15 IU/mL from week 4 to 22 (extended rapid virologic response; eRVR) stopped all treatment at week 24; all other patients continued Peg-IFNα-2a/RBV to complete 48 weeks of treatment. The primary efficacy endpoint was sustained virologic response (SVR; HCV RNA <15 IU/mL after 24 weeks of treatment-free follow-up). SVR was achieved in 56.8% (95% confidence interval [CI]: 45.9-67.0) of mericitabine-treated patients and 36.5% (95% CI: 27.0-47.1) of placebo-treated patients (Δ = 20.3%; 95% CI 5.5-35.2). SVR rates were higher in mericitabine- than placebo-treated patients when subdivided by IL28B genotype (CC, 77.8% versus 56.0%; non-CC, 44.1% versus 16.2%) and hepatic fibrosis (noncirrhotic, 63.3% versus 41.9%; cirrhotic, 38.1% versus 21.7%). Overall relapse rates were 27.7% and 32.0% in mericitabine- and placebo-treated patients, respectively. No evidence of NS5B S282T-variant virus or phenotypic resistance to mericitabine was observed in the one patient who experienced partial response. No S282T variants were detected in any baseline samples. The safety profile of mericitabine was similar to that of, and fewer patients in the mericitabine than in the placebo group discontinued treatment for safety reasons.. A 24-week response-guided combination regimen of mericitabine 1,000 mg BID plus Peg-IFNα-2a/RBV is well tolerated and more effective than a standard 48-week course of Peg-IFNα-2a/RBV.

Topics: Adolescent; Adult; Aged; Canada; Deoxycytidine; Double-Blind Method; Drug Resistance, Viral; Drug Therapy, Combination; Female; Genotype; Hepacivirus; Hepatitis C, Chronic; Humans; Interferon-alpha; Interferons; Interleukins; Male; Middle Aged; Polyethylene Glycols; Recombinant Proteins; Ribavirin; Treatment Outcome; United States; Young Adult

Although interleukin 28B (interferon, lambda 3) (IL28B) genotype affects the response of patients with chronic hepatitis C to peginterferon and ribavirin, little is known regarding its effect on response to direct-acting antivirals in interferon-free combinations. We analyzed the effects of IL28B genotype on the viral kinetic (VK) response to an interferon-free combination of the nucleoside polymerase inhibitor mericitabine (RG7128) and the hepatitis C virus (HCV) protease inhibitor danoprevir.. We performed a double-blind, dose-escalation study of patients with chronic HCV genotype 1 infection who were interferon treatment naive or had not responded to previous therapy with peginterferon and ribavirin. Patients were sequentially assigned to 1 of 7 cohorts then randomly assigned to groups that received up to 13 days of treatment with mericitabine (500 or 1000 mg, twice daily) plus danoprevir (100 or 200 mg, every 8 hours, or 600 or 900 mg, twice daily) or placebo. Eighty-three of 87 patients were genotyped for the IL28B single-nucleotide polymorphism rs12979860. VKs were analyzed only in patients who received 13 days of treatment, at optimal doses, using a biphasic model to describe first- and second-phase slopes of viral decay during therapy.. At day 14 (the end of interferon-free treatment), the mean reduction in the serum level of HCV RNA was slightly greater in patients with the CC polymorphism (5.01 log(10) IU/mL) than those without (4.59 log(10) IU/mL). Modeling revealed that patients with the CC polymorphism had slightly better early VKs, most apparent in the β-phase of viral decay. A mixed effect on the α-phase was observed, which was reduced in magnitude but prolonged in patients with CC, who also had better on-treatment response to peginterferon and ribavirin during follow up.. IL28B genotype appears to affect early VKs in patients with chronic hepatitis C receiving interferon-free treatment.

Topics: Antiviral Agents; Australia; Cyclopropanes; Deoxycytidine; Double-Blind Method; Drug Therapy, Combination; Genotype; Hepacivirus; Hepatitis C, Chronic; Humans; Interferons; Interleukins; Isoindoles; Kinetics; Lactams; Lactams, Macrocyclic; Models, Biological; Models, Statistical; New Zealand; Phenotype; Polymorphism, Single Nucleotide; Proline; RNA, Viral; Sulfonamides; Treatment Outcome; Viral Load; Virus Replication

In the INFORM-1 study, 73 patients with chronic hepatitis C virus infection received mericitabine plus danoprevir for up to 13 days. Seventy-two patients experienced a continuous decline in HCV RNA levels during treatment, and of these patients, 14 had viral loads that remained >1,000 IU/ml by day 13 and 1 met the definition for viral breakthrough. In-depth NS5B and NS3/4A population and clonal sequencing studies and mericitabine and danoprevir drug susceptibility testing were performed to assess the variability and quasispecies dynamics before and upon monotherapy or dual therapy. Sequence analysis of the viral quasispecies indicated that the mericitabine resistance mutation S282T was not present at baseline, nor was it selected (even at a low level) during treatment. Protease inhibitor resistance mutations, either as predominant or as minority species, were detected in 18 patients at baseline. No enrichment of minority protease inhibitor-resistant variants present at baseline was observed during treatment; viral population samples were fully susceptible to mericitabine and/or danoprevir, despite the presence within their quasispecies of minority variants confirmed to have reduced susceptibility to danoprevir or other protease inhibitors. It was also observed that certain NS3 amino acid substitutions affected protease inhibitor drug susceptibility in a compound-specific manner and varied with the genetic context. In summary, the slower kinetics of viral load decline observed in some patients was not due to the selection of danoprevir or mericitabine resistance during treatment. Over 2 weeks' therapy, mericitabine suppressed the selection of danoprevir resistance, results that could differ upon longer treatment periods.

Topics: Adult; Antiviral Agents; Cyclopropanes; Deoxycytidine; Double-Blind Method; Drug Administration Schedule; Drug Resistance, Viral; Drug Therapy, Combination; Enzyme Inhibitors; Hepacivirus; Hepatitis C, Chronic; Humans; Isoindoles; Lactams; Lactams, Macrocyclic; Mutation; Placebos; Proline; RNA, Viral; Sulfonamides; Viral Load; Viral Nonstructural Proteins

RG7128 (prodrug of PSI-6130) shows potent antiviral efficacy in patients infected with hepatitis C virus (HCV) genotypes 1, 2, or 3, with mean viral load decreases of 2.7 and 5 log(10) IU/mL, respectively, associated with 1500-mg doses twice daily after monotherapy for 2 weeks and with 1000-mg and 1500-mg doses twice daily after treatment in combination with the standard of care (SOC) for 4 weeks.. From 32 patients treated with RG7128 monotherapy for 2 weeks, marginal viral load rebound was observed in 3 HCV genotype 1-infected patients, whereas partial response was observed in 2 genotype 1-infected patients. From 85 patients receiving RG7128 in combination with SOC, 1 HCV genotype 1-infected patient experienced a viral rebound, and 2 genotype 3-infected patients experienced a transient rebound. Five genotype 1-infected patients had an HCV load of >1000 IU/mL at the end of 4-week treatment. No viral resistance was observed, per NS5B sequencing and phenotypic studies. PSI-6130 resistance substitution S282T needs to be present at levels of ≥90% within a patient's quasispecies to confer low-level resistance. No evidence of S282T was found by population or clonal sequence analyses.. The requirement for a predominant S282T mutant quasispecies, its low replication capacity, and the low-level resistance it confers probably contribute to the lack of RG7128 resistance observed in HCV-infected patients.

Topics: Amino Acid Substitution; Antiviral Agents; Deoxycytidine; Drug Resistance, Viral; Drug Therapy, Combination; Hepacivirus; Hepatitis C, Chronic; Humans; Interferon alpha-2; Interferon-alpha; New Zealand; Polyethylene Glycols; Recombinant Proteins; Ribavirin; Selection, Genetic; United States; Viral Load; Viral Nonstructural Proteins; Virus Replication

Present interferon-based standard of care treatment for chronic hepatitis C virus (HCV) infection is limited by both efficacy and tolerability. We assessed the safety, tolerability, and antiviral activity of an all-oral combination treatment with two experimental anti-HCV drugs-RG7128, a nucleoside polymerase inhibitor; and danoprevir, an NS3/4A protease inhibitor-in patients with chronic HCV infection.. Patients from six centres in New Zealand and Australia who were chronically infected with HCV genotype 1 received up to 13 days oral combination treatment with RG7128 (500 mg or 1000 mg twice daily) and danoprevir (100 mg or 200 mg every 8 h or 600 mg or 900 mg twice daily) or placebo. Eligible patients were sequentially enrolled into one of seven treatment cohorts and were randomly assigned by interactive voice or web response system to either active treatment or placebo. Patients were separately randomly assigned within each cohort with a block size that reflected the number of patients in the cohort and the ratio of treatment to placebo. The random allocation schedule was computer generated. Dose escalation was started in HCV treatment-naive patients; standard of care treatment-experienced patients, including previous null responders, were enrolled in higher-dose danoprevir cohorts. Investigators, personnel at the study centre, and patients were masked to treatment allocation. However, the pharmacist who prepared the doses, personnel involved in pharmacokinetic sample analyses, statisticians who prepared data summaries, and the clinical pharmacologists who reviewed the data before deciding to initiate dosing in the next cohort were not masked to treatment allocation. The primary outcome was change in HCV RNA concentration from baseline to day 14 in patients who received 13 days of combination treatment. All patients who completed treatment with the study drugs were included in the analyses. This study is registered with ClinicalTrials.gov, NCT00801255.. 88 patients were randomly assigned to a study drug treatment regimen (n=74 over seven treatment groups; 73 received at least one dose of study drug) or to placebo (n=14, all of whom received at least one dose). The median change in HCV RNA concentration from baseline to day 14 ranged from -3·7 to -5·2 log(10) IU/mL in the cohorts that received 13 days of combination treatment. At the highest combination doses tested (1000 mg RG7128 and 900 mg danoprevir twice daily), the median change in HCV RNA concentration from baseline to day 14 was -5·1 log(10) IU/mL (IQR -5·6 to -4·7) in treatment-naive patients and -4·9 log(10) IU/mL in previous standard of care null responders (-5·2 to -4·5) compared with an increase of 0·1 log(10) IU/mL in the placebo group. The combination of RG7128 and danoprevir was well tolerated with no treatment-related serious or severe adverse events, no grade 3 or 4 changes in laboratory parameters, and no safety-related treatment discontinuations.. This oral combination of a nucleoside analogue polymerase inhibitor and protease inhibitor holds promise as an interferon-free treatment for chronic HCV.. Roche Palo Alto.

Topics: Administration, Oral; Adult; Antiviral Agents; Cyclopropanes; Deoxycytidine; Double-Blind Method; Drug Therapy, Combination; Female; Hepacivirus; Hepatitis C, Chronic; Humans; Interferon alpha-2; Interferon-alpha; Isoindoles; Lactams; Lactams, Macrocyclic; Male; Middle Aged; Polyethylene Glycols; Proline; Recombinant Proteins; RNA, Viral; Sulfonamides; Viral Nonstructural Proteins

Toxicity has emerged during the clinical development of many but not all nucleotide inhibitors (NI) of hepatitis C virus (HCV). To better understand the mechanism for adverse events, clinically relevant HCV NI were characterized in biochemical and cellular assays, including assays of decreased viability in multiple cell lines and primary cells, interaction with human DNA and RNA polymerases, and inhibition of mitochondrial protein synthesis and respiration. NI that were incorporated by the mitochondrial RNA polymerase (PolRMT) inhibited mitochondrial protein synthesis and showed a corresponding decrease in mitochondrial oxygen consumption in cells. The nucleoside released by the prodrug balapiravir (R1626), 4'-azido cytidine, was a highly selective inhibitor of mitochondrial RNA transcription. The nucleotide prodrug of 2'-C-methyl guanosine, BMS-986094, showed a primary effect on mitochondrial function at submicromolar concentrations, followed by general cytotoxicity. In contrast, NI containing multiple ribose modifications, including the active forms of mericitabine and sofosbuvir, were poor substrates for PolRMT and did not show mitochondrial toxicity in cells. In general, these studies identified the prostate cell line PC-3 as more than an order of magnitude more sensitive to mitochondrial toxicity than the commonly used HepG2 cells. In conclusion, analogous to the role of mitochondrial DNA polymerase gamma in toxicity caused by some 2'-deoxynucleotide analogs, there is an association between HCV NI that interact with PolRMT and the observation of adverse events. More broadly applied, the sensitive methods for detecting mitochondrial toxicity described here may help in the identification of mitochondrial toxicity prior to clinical testing.

Topics: Antiviral Agents; Cell Line; Deoxycytidine; DNA Polymerase gamma; DNA-Directed DNA Polymerase; DNA-Directed RNA Polymerases; Guanosine Monophosphate; Hepacivirus; Hepatitis C, Chronic; Humans; Mitochondria; Nucleosides; Oxygen Consumption; Protein Biosynthesis; RNA; RNA, Mitochondrial; Sofosbuvir; Transcription, Genetic; Virus Replication

The aim was to evaluate early viral kinetics in patients receiving mericitabine [hepatitis C virus (HCV) nucleoside polymerase inhibitor] with peginterferon alfa-2a (40KD) and ribavirin in two clinical trials (PROPEL and JUMP-C).. We examined rapid virological responses (RVRs; week 4 HCV RNA <15 IU ml(-1) ) and complete early virological responses (cEVR; week 12 HCV RNA <15 IU ml(-1) ) in HCV genotype 1/4-infected patients receiving mericitabine (500 or 1000 mg) or placebo twice daily plus peginterferon alfa-2a and ribavirin.. Among IL28B rs12979860 CC genotype patients receiving 500 or 1000 mg mericitabine or placebo, respectively, RVR rates were 64.3% (95% confidence interval: 38.8-83.7%), 95.1% (83.9-98.7%) and 33.3% (20.2-49.7%), and cEVR rates were 100% (78.5-100%), 100% (91.4-100%) and 80.6% (65.0-90.3%). Among non-CC genotype patients, RVR rates were 26.5% (14.6-43.1%), 52.3% (43.0-61.3%) and 5.7% (2.2-13.8%), and cEVR rates were 76.5% (60.0-87.6%), 84.6% (76.6-90.1%) and 28.6% (19.3-40.1%), respectively. In multiple regression analysis, IL28B genotype (P < 0.0001), mericitabine dose (P < 0.0001) and bodyweight (P = 0.0009) were associated with first-phase (α) slope (change in log10 HCV RNA from baseline to week 1).. Mericitabine-containing triple therapy reduces the impact of IL28B genotype on RVR and cEVR compared with peginterferon alfa-2a and ribavirin dual therapy. The IL28B genotype, mericitabine dose and bodyweight are the most important factors associated with the α slope, and there is no evidence of a pharmacokinetic drug-drug interaction between mericitabine and ribavirin.

Topics: Adult; Aged; Antiviral Agents; Clinical Trials, Phase II as Topic; Deoxycytidine; Drug Therapy, Combination; Female; Genotype; Hepacivirus; Hepatitis C, Chronic; Humans; Interferon-alpha; Interferons; Interleukins; Male; Middle Aged; Polyethylene Glycols; Randomized Controlled Trials as Topic; Recombinant Proteins; Retrospective Studies; Ribavirin; Treatment Outcome; Young Adult

Topics: Deoxycytidine; Female; Genotype; Hepacivirus; Hepatitis C, Chronic; Humans; Interferon-alpha; Male; Polyethylene Glycols; Recombinant Proteins; Ribavirin

Topics: Administration, Oral; Antiviral Agents; Cyclopropanes; Deoxycytidine; Drug Therapy, Combination; Hepacivirus; Hepatitis C, Chronic; Humans; Isoindoles; Lactams; Lactams, Macrocyclic; Proline; Sulfonamides; Viral Nonstructural Proteins