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Background: The pharmacokinetics and safety of velpatasvir, a potent pangenotypic hepatitis C virus NS5A inhibitor, were evaluated in two hepatic impairment studies: a phase I study in hepatitis C virus-uninfected subjects and a phase III study (ASTRAL-4) in hepatitis C virus-infected patients.Methods: In the phase I study, subjects with moderate or severe hepatic impairment (Child-Pugh-Turcotte Class B or C), and demographically matched subjects with normal hepatic function received a single dose of velpatasvir 100 mg. Pharmacokinetics and safety assessments were performed, and pharmacokinetic parameters were calculated using non-compartmental methods and summarized using descriptive statistics and compared statistically by geometric least-squares mean ratios and 90% confidence intervals. In ASTRAL-4, subjects with decompensated cirrhosis (Child-Pugh-Turcotte Class B) were randomized to receive treatment with either sofosbuvir/velpatasvir ± ribavirin for 12 weeks or sofosbuvir/velpatasvir for 24 weeks. Pharmacokinetic and safety assessments were performed and pharmacokinetic parameters were calculated using a non-compartmental analysis and summarized using descriptive statistics and were compared to pharmacokinetics from ASTRAL-1 [subjects without cirrhosis or with compensated (Child-Pugh-Turcotte Class A) cirrhosis].Results: In the phase I study, plasma exposures (area under the concentration-time curve) were similar in subjects with Child-Pugh-Turcotte Class B (n = 10) or Child-Pugh-Turcotte Class C hepatic impairment (n = 10) compared with normal hepatic function (n = 13). Percent free velpatasvir was similar in subjects without or with any degree of hepatic impairment. In the phase III study, velpatasvir overall exposure (area under the concentration-time curve over the 24-h dosing interval; AUCtau) was similar and sofosbuvir exposures were higher (~ 100%) for patients with Child-Pugh-Turcotte Class B hepatic impairment compared with the ASTRAL-1 population, which was not considered clinically relevant.Conclusions: No sofosbuvir/velpatasvir dose modification is warranted for patients with any degree of hepatic impairment. [ABSTRACT FROM AUTHOR]

Ledipasvir/sofosbuvir (Harvoni®), a fixed-dose combination tablet of an NS5A inhibitor ledipasvir and an NS5B polymerase inhibitor sofosbuvir, is approved for the treatment of chronic hepatitis C virus infection. Ledipasvir/sofosbuvir exhibits a favorable drug-drug interaction profile and can be administered with various medications that may be used by hepatitis C virus-infected patients, including patients with comorbidities, such as co-infection with human immunodeficiency virus or immunosuppression following liver transplantation. Ledipasvir/sofosbuvir is not expected to act as a victim or perpetrator of cytochrome P450- or UDP-glucuronosyltransferase 1A1-mediated drug-drug interactions. With the exception of strong inducers of P-glycoprotein, such as rifampin, ledipasvir/sofosbuvir is not expected to act as a victim of clinically relevant drug-drug interactions. As a perpetrator of pharmacokinetic drug-drug interactions via P-glycoprotein/BCRP, ledipasvir/sofosbuvir should not be used with rosuvastatin and elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate, whereas its co-administration with amiodarone is not recommended because of a pharmacodynamic interaction. This review summarizes a number of drug interaction studies conducted in support of the clinical development of ledipasvir/sofosbuvir. [ABSTRACT FROM AUTHOR]

Background. A safe, simple, effective, and pan-genotypic regimen to treat hepatitis C virus (HCV) infection in patients coinfected with human immunodeficiency virus type 1 (HIV-1) remains a medical need. We assessed the efficacy and safety of the NS5B polymerase inhibitor sofosbuvir and the NS5A inhibitor velpatasvir for HCV in patients coinfected with HIV-1. Methods. This phase 3, open-label, single-arm study at 17 sites in the United States enrolled patients with HCV of any genotype and HIV-1 coinfection, including those with compensated cirrhosis. All patients received sofosbuvir-velpatasvir once daily for 12 weeks. The primary endpoint was sustained virologic response 12 weeks after treatment (SVR12). Efficacy and safety were assessed in all patients receiving at least 1 dose of treatment. Results. Of 106 patients, 91 (86%) were men, 48 (45%) were black, and 19 (18%) had cirrhosis. SVR12 was achieved by 101 of 106 (95% [95% confidence interval {CI}, 89%-99%]) patients: 74 of 78 (95% [95% CI, 87%-99%]) with genotype 1; all 11 (100% [95% CI, 72%-100%]) with genotype 2; 11 of 12 (92% [95% CI, 62%-100%]) with genotype 3; and all 5 (100% [95% CI, 48%-100%]) with genotype 4. All 19 patients with cirrhosis had SVR12. Two patients relapsed, 2 were lost to follow-up, and 1 withdrew consent. Two discontinued treatment due to adverse events and 2 had serious adverse events. The most common adverse events were fatigue (25%), headache (13%), upper respiratory tract infection (8%), and arthralgia (8%). Conclusions. Sofosbuvir-velpatasvir for 12 weeks was safe and provided high rates of SVR12 in patients coinfected with HCV and HIV-1. [ABSTRACT FROM AUTHOR]

Background. Patients chronically infected with genotype 3 hepatitis C virus (HCV) have faster disease progression and are less responsive to current direct-acting antiviral regimens than patients infected with other genotypes. We conducted an open-label trial to evaluate the safety, tolerability, and efficacy of ledipasvir and sofosbuvir plus ribavirin in patients with genotype 3 HCV infection. Methods. We enrolled treatment-naive patients with and without compensated cirrhosis at 15 sites in Canada. All patients were treated with ledipasvir-sofosbuvir (90 mg and 400 mg) plus weight-based ribavirin for 12 weeks. The primary endpoint was sustained virologic response 12 weeks after treatment (SVR12). Secondary endpoints included evaluation of baseline and treatment-emergent drug resistance. Results. Of the 111 patients enrolled, 105 (95%) had subtype 3a HCV and 39 (35%) had compensated cirrhosis. SVR12 was achieved by 99 of 111 patients (89%; 95% confidence interval, 82%-94%). Of the 39 patients with cirrhosis, 31 (79%) achieved SVR12, compared with 68 of 72 (94%) patients without cirrhosis. No treatment-emergent resistance mutations occurred in those who failed treatment. One patient discontinued treatment due to liver cancer and died 22 days after treatment discontinuation. The most common adverse events were fatigue (51%), headache (36%), and nausea (23%). Conclusions. In this multicenter trial involving treatment-naive patients with genotype 3 HCV, 12 weeks of ledipasvir-sofosbuvir provided a high level of SVR in those without cirrhosis. [ABSTRACT FROM AUTHOR]

Background. Historically, acute hepatitis C virus (HCV) infection was treated with shorter durations of interferon-containing therapies. In the era of direct-acting antivirals (DAAs), it is unclear whether the efficacy of treatment achieved in chronic infection can be maintained with abbreviated courses of therapy during the acute phase. Methods. The sofosbuvir-containing regimens without interferon for treatment of acute HCV in HIV-1 infected individuals (SWIFT-C) is an open-label, 2-cohort clinical trial in which the first cohort assessed for the safety and efficacy of 12 weeks of sofosbuvir plus ribavirin for the treatment of acute HCV infection in participants with chronic human immunodeficiency virus type 1 (HIV-1) infection. This is a preplanned analysis of the first cohort, which had a planned accrual of 17 participants. Results. Seventeen men (11 Hispanic, 6 white, median age 45 years) were enrolled. Most (88%) had HCV genotype-1 infection and few (24%) had the favorable IL28B CC genotype. Median baseline HCV RNA was 2 280 000 IU/mL (interquartile range, 272 000-4 230 000). Ten participants (59%) achieved the primary outcome of SVR12 (90% confidence interval, 36%-78%), failing to establish noninferiority. All treatment failures were due to viral relapse (41%). There were no premature treatment discontinuations. The only factor that differed between participants who achieved SVR vs those who relapsed was ribavirin concentration at the end of treatment. Conclusion. Sofosbuvir-ribavirin for 12 weeks for the treatment of acute HCV genotype-1 infection in HIV-1-infected persons results in a high relapse rate. Preliminary studies of DAA combination therapies suggest improved response rates, although the adequate duration of therapy remains unclear. [ABSTRACT FROM AUTHOR]

Background. The development of direct-acting antivirals in recent years has dramatically enhanced rates of viral eradication to >90% in patients with chronic hepatitis C virus (HCV) infection. To determine true treatment efficacy and define the most appropriate retreatment, it is important to distinguish virologic relapse from reinfection when patients in whom HCV is eradicated during treatment become infected with a new HCV strain after treatment. Methods. We investigated the prevalence of late recurrent viremia (patients with sustained virologic response 12 weeks after the end of treatment but detectable HCV RNA at follow-up week 24) and used refined phylogenetic analysis of multiple HCV genes to distinguish virologic relapse from reinfection. Results. Across 11 phase 3 clinical trials of ledipasvir-sofosbuvir (SOF) and SOF, only 12 of 3004 patients had detectable HCV RNA following sustained virologic response 12 weeks after the end of treatment. Of these 12 patients with late recurrent viremia, 11 had the same HCV genotype/subtype at baseline and at recurrence. Phylogenetic analysis demonstrated that 58% (7 of 12) of these patients were successfully treated with the SOF-based regimen, with HCV eradication achieved, but became reinfected with a different HCV strain after treatment. The remaining 5 patients with late recurrent viremia had virologic relapse in which the HCV present at baseline persisted in the liver or another compartment and reemerged in the blood 24 weeks after treatment. Conclusions. The incidence of late recurrent viremia was low. Distinguishing reinfection from virologic relapse has implications for determining true treatment efficiency and selecting optimal retreatment strategies. [ABSTRACT FROM AUTHOR]

Background. Interferon-based hepatitis C virus (HCV) therapy is safe and effective among people receiving opioid substitution therapy (OST), but treatment uptake remains low. Our aim was to evaluate the impact of OST and drug use during therapy on completion, adherence, sustained virologic response (SVR12), and safety of ledipasvir/sofosbuvir ± ribavirin. Methods. The phase 3 ION studies evaluated a fixed-dose combination of ledipasvir/sofosbuvir ± ribavirin administered for 8, 12, or 24 weeks in patients with chronic HCV genotype 1. People with clinically significant drug use ( prior 12 months) or noncannabinoids detected at screening by urine drug tests (not explained by prescriptions) were ineligible. Stored samples were available from ION-1 for retrospective testing for illicit drugs by enzyme-linked immunosorbent assay. Results. Among 1952 patients enrolled in the ION studies, 4% (n = 70) were receiving OST. Among those receiving (n = 70) and not receiving OST (n = 1882), there was no difference in treatment completion (97% vs 98%; P = .40), ⩾80% adherence (93% vs 92%; P = 1.00), SVR12 (94% vs 97%; P = .28), and serious adverse events (4% vs 3%; P = .43), respectively. Among participants in the ION-1 trial, 23% (n = 196) used illicit drugs during therapy (15% cannabinoids alone; 8% other illicit drugs ± cannabinoids). There was no difference in treatment completion, ⩾80% adherence, SVR12, or serious AEs in those with no drug use during treatment compared with those who used cannabinoids and/or other illicit drugs. No cases of HCV reinfection were observed in the 24 weeks following treatment. Conclusions. OST and drug use during HCV therapy did not impact treatment completion, adherence, SVR12, or safety. [ABSTRACT FROM AUTHOR]

Background: Effective, pangenotypic treatments for hepatitis C virus (HCV) infection are needed.Objective: To assess the safety and efficacy of sofosbuvir with velpatasvir in patients infected with HCV genotypes 1 to 6.Design: Randomized, phase 2, open-label study. (ClinicalTrials.gov: NCT01858766).Setting: 48 U.S. sites.Patients: 377 treatment-naive noncirrhotic patients. In part A, patients infected with HCV genotypes 1 to 6 were randomly assigned to sofosbuvir, 400 mg, with velpatasvir, 25 or 100 mg, for 12 weeks. In part B, patients with genotype 1 or 2 HCV infection were randomly assigned to sofosbuvir, 400 mg, and velpatasvir, 25 or 100 mg, with or without ribavirin for 8 weeks.Measurements: Sustained virologic response at 12 weeks (SVR12).Results: In part A, SVR12 rates were 96% (26 of 27) with velpatasvir, 25 mg, and 100% (28 of 28) with velpatasvir, 100 mg, for genotype 1; 93% (25 of 27) in both groups for genotype 3; and 96% (22 of 23) with velpatasvir, 25 mg, and 95% (21 of 22) with velpatasvir, 100 mg, for genotypes 2, 4, 5, and 6. In part B, for genotype 1, SVR12 rates were 87% (26 of 30) with velpatasvir, 25 mg; 83% (25 of 30) with velpatasvir, 25 mg, plus ribavirin; 90% (26 of 29) with velpatasvir, 100 mg; and 81% (25 of 31) with velpatasvir, 100 mg, plus ribavirin. For genotype 2, SVR12 rates were 77% (20 of 26) with velpatasvir, 25 mg; 88% (22 of 25) with velpatasvir, 25 mg, plus ribavirin; 88% (23 of 26) with velpatasvir, 100 mg; and 88% (23 of 26) with velpatasvir, 100 mg, plus ribavirin. Adverse events included fatigue (21%), headache (20%), and nausea (12%). One patient committed suicide.Limitation: The study was open-label, no inferential statistics were planned, and sample sizes were small.Conclusion: Twelve weeks of sofosbuvir, 400 mg, and velpatasvir, 100 mg, was well-tolerated and resulted in high SVR in patients infected with HCV genotypes 1 to 6.Primary Funding Source: Gilead Sciences. [ABSTRACT FROM AUTHOR]

Background: Effective treatment options are needed for patients with genotype 1 or 3 hepatitis C virus (HCV) infection in whom previous therapy has failed.Objective: To assess the efficacy and safety of sofosbuvir plus velpatasvir, with and without ribavirin, in treatment-experienced patients.Design: Randomized, phase 2, open-label study. (ClinicalTrials.gov: NCT01909804).Setting: 58 sites in Australia, New Zealand, and the United States.Patients: Treatment-experienced adults with genotype 3 HCV infection without cirrhosis (cohort 1) and with compensated cirrhosis (cohort 2) and patients with genotype 1 HCV infection that was unsuccessfully treated with a protease inhibitor with peginterferon and ribavirin (50% could have compensated cirrhosis) (cohort 3).Intervention: All patients received 12 weeks of treatment that included 400 mg of sofosbuvir once daily. Patients in each cohort were randomly assigned to 25 mg of velpatasvir once daily with or without ribavirin or 100 mg of velpatasvir once daily with or without ribavirin.Measurements: Proportion of patients with sustained virologic response at week 12 after treatment (SVR12).Results: In cohort 1, SVR12 rates were 85% with 25 mg of velpatasvir, 96% with 25 mg of velpatasvir plus ribavirin, 100% with 100 mg of velpatasvir, and 100% with 100 mg of velpatasvir plus ribavirin. In cohort 2, SVR12 rates were 58% with 25 mg of velpatasvir, 84% with 25 mg of velpatasvir plus ribavirin, 88% with 100 mg of velpatasvir, and 96% with 100 mg of velpatasvir plus ribavirin. In cohort 3, SVR12 rates were 100% with 25 mg of velpatasvir, 97% with 25 mg of velpatasvir plus ribavirin, 100% with 100 mg of velpatasvir, and 96% with 100 mg of velpatasvir plus ribavirin. The most common adverse events were headache, fatigue, and nausea.Limitation: Treatment assignments were not blinded, and no inferential statistics were planned.Conclusion: Treatment with 400 mg of sofosbuvir plus 100 mg of velpatasvir for 12 weeks was well-tolerated and highly effective in treatment-experienced patients with genotype 1 or 3 HCV infection.Primary Funding Source: Gilead Sciences. [ABSTRACT FROM AUTHOR]

In this analysis of the ASTRAL trials (non-opioid substitution therapy [OST], n = 984; OST, n = 51) evaluating the once-daily, pan-genotypic regimen of sofosbuvir/velpatasvir for hepatitis C virus infection, OST did not impact completion, adherence, sustained virologic response (SVR12), or safety. SVR12 was 96% (95% confidence interval, 87%, >99%) in those receiving OST. [ABSTRACT FROM AUTHOR]

Postmarketing cases of hepatitis B virus (HBV) reactivation during hepatitis C treatment have been reported. We analyzed serum samples from patients in a clinical trial of ledipasvirsofosbuvir in Taiwan and Korea. Of the 173 patients enrolled, 103 (60%) had been previously infected with HBV. None showed evidence of HBV reactivation. [ABSTRACT FROM AUTHOR]

Background & Aims The fixed-dose combination of sofosbuvir/velpatasvir was highly efficacious in patients infected with genotype (GT)1–6 hepatitis C virus (HCV) in the ASTRAL studies. This analysis evaluated the impact of baseline resistance-associated substitutions (RASs) on treatment outcome and emergence of RASs in patients infected with HCV GT1-6 who were treated with sofosbuvir/velpatasvir. Methods Non-structural protein 5A and 5B (NS5A and NS5B ) deep sequencing was performed at baseline and at the time of relapse for all patients treated with sofosbuvir/velpatasvir for 12 weeks (n = 1,778) in the ASTRAL-1–3, ASTRAL-5 and POLARIS-2–3 studies. Results Patients with 37 known and 19 novel HCV subtypes were included in these analyses. Overall, 28% (range 9% to 61% depending on genotype) had detectable NS5A class RASs at baseline, using a 15% sequencing assay cut-off. There was no significant effect of baseline NS5A class RASs on sustained virologic response at week 12 (SVR12) with sofosbuvir/velpatasvir; the SVR12 rate in the presence of NS5A class RASs was 100% and 97%, in patients with GT1a and GT1b infection, respectively, and 100% in patients with GT2 and GT4–6 infections. In GT3 infection, the SVR rate was 93% and 98% in patients with and without baseline NS5A class RASs, respectively. The overall virologic failure rate was low (20/1,778 = 1.1%) in patients treated with sofosbuvir/velpatasvir. Single NS5A class resistance was observed at virologic failure in 17 of the 20 patients. Conclusions Sofosbuvir/velpatasvir taken for 12 weeks once daily resulted in high SVR rates in patients infected with GT1–6 HCV, irrespective of baseline NS5A RASs. NS5A inhibitor resistance, but not sofosbuvir resistance, was detected in the few patients with virologic failure. These data highlight the high barrier to resistance of this regimen for the treatment of chronic HCV across all genotypes in the vast majority of patients. Lay summary Sofosbuvir/velpatasvir taken once daily for 12 weeks resulted in high sustained virologic response rates in patients infected with HCV, irrespective of the presence of NS5A resistance-associated variants prior to treatment. Single class NS5A inhibitor resistance, but not sofosbuvir resistance, was detected in the few patients with virologic failure. These data highlight the high barrier to resistance of this regimen for the treatment of chronic HCV across all genotypes in the vast majority of patients. [ABSTRACT FROM AUTHOR]

Background & Aims The efficacy of NS5A inhibitors for the treatment of patients chronically infected with hepatitis C virus (HCV) can be affected by the presence of NS5A resistance-associated substitutions (RASs). We analyzed data from 35 phase I, II, and III studies in 22 countries to determine the pretreatment prevalence of various NS5A RASs, and their effect on outcomes of treatment with ledipasvir-sofosbuvir in patients with genotype 1 HCV. Methods NS5A gene deep sequencing analysis was performed on samples from 5397 patients in Gilead clinical trials. The effect of baseline RASs on sustained virologic response (SVR) rates was assessed in the 1765 patients treated with regimens containing ledipasvir-sofosbuvir. Results Using a 15% cut-off, pretreatment NS5A and ledipasvir-specific RASs were detected in 13% and 8% of genotype 1a patients, respectively, and in 18% and 16% of patients with genotype 1b. Among genotype 1a treatment-naïve patients, SVR rates were 91% (42/46) vs. 99% (539/546) for those with and without ledipasvir-specific RASs, respectively. Among treatment-experienced genotype 1a patients, SVR rates were 76% (22/29) vs. 97% (409/420) for those with and without ledipasvir-specific RASs, respectively. Among treatment-naïve genotype 1b patients, SVR rates were 99% for both those with and without ledipasvir-specific RASs (71/72 vs. 331/334), and among treatment-experienced genotype 1b patients, SVR rates were 89% (41/46) vs. 98% (267/272) for those with and without ledipasvir-specific RASs, respectively. Conclusions Pretreatment ledipasvir-specific RASs that were present in 8--16% of patients have an impact on treatment outcome in some patient groups, particularly treatment-experienced patients with genotype 1a HCV. Lay summary The efficacy of treatments using NS5A inhibitors for patients with chronic hepatitis C virus (HCV) infection can be affected by the presence of NS5A resistance-associated substitutions (RASs). We reviewed results from 35 clinical trials where patients with genotype 1 HCV infection received treatments that included ledipasvir-sofosbuvir to determine how prevalent NS5A RASs are in patients at baseline, and found that ledipasvir-specific RASs were present in 8--16% of patients prior to treatment and had a negative impact on treatment outcome in subset of patient groups, particularly treatment-experienced patients with genotype 1a HCV. [ABSTRACT FROM AUTHOR]

Background & Aims Ledipasvir/sofosbuvir combination treatment in phase III clinical trials resulted in sustained viral suppression in 94–99% of patients. This study characterized drug resistance in treatment failures, which may help to inform retreatment options. Methods We performed NS5A and NS5B deep sequencing of hepatitis C virus (HCV) from patients infected with genotype (GT) 1 who participated in ledipasvir/sofosbuvir phase II and III clinical trials. Results Fifty-one of 2144 (2.4%) (42 GT1a and 9 GT1b) treated patients met the criteria for resistance analysis due to virologic failure following the end of treatment. The majority of patients with virologic failure (38 of 51; 74.5%) had detectable ledipasvir-specific resistance-associated substitutions (RASs) at the time of virologic failure (1% deep sequencing cut-off). The percent of patients with NS5A RASs at virologic failure were 37.5%, 66.7%, 94.7% and 100% in patients treated for 6, 8, 12 and 24 weeks, respectively. The common substitutions detected at failure were Q30R/H, and/or Y93H/N in GT1a and Y93H in GT1b. At failure, 35.3% (18/51) of virologic failure patients’ viruses had two or more NS5A RASs and the majority of patients harbored NS5A RASs conferring a 100–1000-fold (n = 10) or >1000-fold (n = 23) reduced susceptibility to ledipasvir. One patient in a phase II study with a known ledipasvir RAS at baseline (L31M) developed the S282T sofosbuvir (NS5B) RAS at failure. Conclusions In GT1 HCV-infected patients treated with ledipasvir/sofosbuvir ± ribavirin, virologic failure was rare. Ledipasvir resistance in NS5A was selected or enhanced in most patients with virologic failure, one of whom also developed resistance to sofosbuvir. Lay summary Clinical studies have shown that combination treatment with ledipasvir/sofosbuvir efficiently cures most patients with genotype 1 hepatitis C infection. For the few patients failing treatment, we show that resistance to ledipasvir was observed in most patients, whereas resistance to sofosbuvir was less common. This has important implications for the selection of optimal retreatment strategies for these patients. [ABSTRACT FROM AUTHOR]

Background Repeated measurements of hepatitis C virus (HCV) RNA levels during antiviral therapy are recommended to monitor treatment efficacy and adherence. Throughout most direct antiviral agent (DAA) approval studies, HCV RNA cutoffs and endpoints were established with the COBAS TaqMan assay for use with the High Pure System (HPS/CTM). Different assays used in clinical practice may yield different quantitative results and possibly impact treatment decisions. Objectives The concordance of the fully-automated COBAS AmpliPrep/COBAS TaqMan assay (CAP/CTM) with HPS/CTM and its ability to predict response to DAA-treatment with ledipasvir/sofosbuvir was assessed in cirrhotic patients with HCV genotype-1-infection who had failed prior treatment with protease inhibitor-based regimens. Study design Serum samples from patients (n = 154) treated in the phase-2 SIRIUS-study were collected at baseline and during antiviral therapy (weeks 1–8), and were tested in parallel by both assays. Results The mean difference between HPS/CTM and CAP/CTM at baseline (n = 153) was 0.32 log 10 IU/mL HCV RNA. Discordant results were observed in 12% of samples collected at treatment weeks 1–8, with the greatest differences observed at weeks 2 and 4 (14% and 29%, respectively, for undetectable HCV RNA). SVR rates were 96%–97% in the study and were not significantly different between patients with detectable vs. undetectable HCV RNA according to both assays at weeks 1–4 of antiviral therapy. Conclusions CAP/CTM and HPS/CTM showed significantly different response rates during the early stages of ledipasvir/sofosbuvir treatment. However, on-treatment response was not predictive of SVR with either assay, indicating that determination of on-treatment HCV RNA levels may not be useful to guide treatment decisions. [ABSTRACT FROM AUTHOR]

The article presents a study that examined the efficacy of the combination of the nucleotide polymerase inhibitor sofosbuvir and the antiviral drug ribavirin in treating patients with hepatitis C virus (HCV) genotype 2 and 3 infections. The study shows higher rates of sustained virologic response gained from therapy in sofosbuvir-ribavirin for 12 weeks in patients with HCV genotype 2 infection and for 24 weeks in patients with HCV genotype 3 infection.

Background & Aims: GS-5885 is an inhibitor of the hepatitis C virus (HCV) NS5A protein and exhibits potent suppression of genotype 1 HCV replicons. The safety, tolerability, pharmacokinetics, antiviral activity, and resistance profile of once-daily GS-5885 doses of 1–90mg were evaluated in patients with chronic genotype 1 HCV. Methods: Genotype 1 HCV-infected patients were randomized to 3days of once-daily (QD) dosing with placebo (n=12) or GS-5885 1mg (n=10), 3mg (n=10), 10mg (n=20), 30mg (n=10), or 90mg (n=10). Plasma samples for pharmacokinetics, HCV RNA, and NS5A sequencing were collected through day 14. Results: GS-5885 was well tolerated and resulted in median maximal reductions in HCV RNA ranging from 2.3 log10 IU/ml (1mg QD) to 3.3 log10 IU/ml (10mg QD in genotype 1b and 30mg QD). Emax modeling indicated GS-5885 30mg was associated with>95% of maximal antiviral response to HCV genotype 1a. HCV RNA reductions were generally more sustained among patients with genotype 1b vs. 1a. Three of 60 patients had a reduced response and harbored NS5A-resistant virus at baseline. NS5A sequencing identified residues 30 and 31 in genotype 1a, and 93 in genotype 1b as the predominant sites of mutation following GS-5885 dosing. Plasma pharmacokinetics was consistent with QD dosing. Conclusions: During 3days of monotherapy, low doses of GS-5885 demonstrated significant antiviral activity in genotype 1a and 1b HCV-infected patients. GS-5885 is currently being evaluated in combination with direct antiviral regimens with and without peginterferon. [Copyright &y& Elsevier]