Sofosbuvir-velpatasvir in adults with hepatitis C virus infection and compensated cirrhosis in Japan.

BACKGROUND & PURPOSE: Protease-free regimens for chronic hepatitis C virus (HCV) infection are safe and effective for persons with either compensated or decompensated cirrhosis. We examined the efficacy and safety of sofosbuvir-velpatasvir in participants with HCV and compensated cirrhosis in Japan. METHODS: This was a Phase 3, multi-center, open-label study. At 20 sites, 37 individuals with chronic HCV infection of any genotype and compensated cirrhosis received sofosbuvir-velpatasvir (400 mg/100 mg) daily for 12 weeks. Participants were treatment-naïve or treatment-experienced with interferon-based treatments with or without HCV NS3/4A protease inhibitors. Prior exposure with HCV NS5A or NS5B inhibitors was prohibited. The primary study endpoint was sustained virologic response 12 weeks after treatment (SVR12). RESULTS: Among participants, 62% had HCV genotype 1 infection, and 38% had HCV genotype 2. More than three quarters (29/37, 78%) were HCV treatment naïve. All participants (37/37, 100%) achieved SVR12. Seventeen participants (46%) and three participants (8%) had pretreatment resistance-associated substitutions to HCV NS5A and NS5B nucleoside inhibitors respectively, yet no on-treatment breakthrough or relapse occurred. Sofosbuvir-velpatasvir for 12 weeks treatment was safe and well tolerated. The most commonly reported adverse events were headache (8%, 3/37) and diarrhea (5%, 2/37). One serious adverse event, patella fracture, occurred and was considered not treatment related. No participants discontinued study treatment due to an adverse event. Three participants (8%) had a Grade 3 laboratory abnormality; all were hyperglycemia. CONCLUSION: Sofosbuvir-velpatasvir resulted in high SVR rates and was well tolerated among Japanese patients with HCV and compensated cirrhosis. This single-tablet regimen offers a highly effective, protease-inhibitor free regimen for treating HCV. CLINICALTRIALS: gov Identifier: NCT04112303.

Sofosbuvir: Really Meets the Unmet Needs for Hepatitis C Treatment?

Chronic hepatitis C remains a major public health concern with a prevalence of more than 1% worldwide. Of late, with the discovery of newer drugs, chronic HCV treatment has touched new dimensions. The treatment has progressed from Interferons to Pegylated interferon (Peg IFN) based therapy, with or without ribavirin to treatment with orally active Direct Acting Antivirals (DAA) with Peg IFN and ribavirin and eventually to various combinations of DAA, without IFN. Introduction of newer DAAs has transfigured the treatment of chronic HCV. Chronic HCV patients with advanced liver disease, psychiatric condition, anemia or autoimmune diseases, not eligible for Peg IFN based therapy have a ray of hope now. Amongst all DAAs, nucleoside inhibitors have been the most promising agent. Thus the present review focuses on Sofosbuvir, one of the most effective nucleoside inhibitors; in terms of potency, resistance profile, activity against all genotypes of HCV and adverse effects. FDA approved Sofobuvir for clinical use in 2013. Chemically, it is 2'-deoxy-2'-α-fluoro-ß-Cmethyluridine- 5'-triphosphate; a phosphoramidate prodrug that is activated by enzyme present in human liver. It is a highly potent inhibitor of HCV NS5B polymerase. Efficacy of the Sofosbuvir has been established in various phase 2 and phase 3 clinical trials like PROTON, ELECTRON, FUSION, POSITRON etc. Sofosbuvir has a good safety profile with few mild to moderate adverse effects. Evidence reveals that sofosbuvir has substantial impact on the treatment of HCV.

Sofosbuvir-velpatasvir single-tablet regimen administered for 12 weeks in a phase 3 study with minimal monitoring in India.

BACKGROUND AND AIMS: In clinical studies, sofosbuvir-velpatasvir has demonstrated high cure rates and favorable tolerability in patients chronically infected with chronic hepatitis C virus (HCV) of any genotype. We evaluated the effectiveness and safety of sofosbuvir-velpatasvir administered with minimal medical monitoring to patients in India. METHODS: At 16 sites in India, 129 adult patients with chronic HCV infection of any genotype initiated 12 weeks of once-daily sofosbuvir-velpatasvir (400-100 mg). Patients with compensated cirrhosis or prior treatment experience could be included in the study. Study drug was dispensed monthly, but there were no on-treatment study assessments. The primary efficacy endpoint was rate of sustained virologic response (HCV RNA < 15 IU/mL) 12 weeks after treatment (SVR12), which was compared to a pre-specified performance goal of 85%. RESULTS: The majority of patients had HCV genotype 3 infection (70%), followed by HCV genotype 1 (22%). The SVR12 rate was 93% (120/129; 95% CI, 87% to 97%) (p = 0.009 compared with the 85% performance goal). Of the nine patients who did not achieve SVR12, 1 experienced virologic failure, 2 relapsed after treatment, 1 withdrew consent after treatment, and 5 were lost to follow-up (1 during and 4 after treatment). Sofosbuvir-velpatasvir was well-tolerated, and no patients discontinued treatment because of an adverse event. The most frequently reported adverse events were headache (3% of patients), upper abdominal pain (2%), and pyrexia (2%). CONCLUSIONS: In this study conducted at multiple sites in India, sofosbuvir-velpatasvir administered without genotype restriction or on-treatment safety assessments was well-tolerated and highly effective.

Sofosbuvir-velpatasvir plus ribavirin in Japanese patients with genotype 1 or 2 hepatitis C who failed direct-acting antivirals.

BACKGROUND/PURPOSE: In Japan, there is a growing population of patients with chronic hepatitis C virus (HCV) infection who failed a direct-acting antiviral (DAA)-based regimen. In this Phase 3 study, we evaluated sofosbuvir-velpatasvir plus ribavirin in Japanese patients with genotype 1 or 2 HCV infection who previously received DAAs. METHODS: Patients were randomized 1:1 to receive sofosbuvir-velpatasvir plus ribavirin for 12 or 24 weeks. Randomization was stratified by HCV genotype and presence of cirrhosis. The primary endpoint was sustained virologic response 12-week post-treatment (SVR12). RESULTS: Of 117 participants, 81% had HCV genotype 1 infection, 33% had cirrhosis, and 95% had NS5A resistance-associated substitutions (RAS) at baseline. Overall, SVR12 rates were 97% (58/60; 95% CI 88-100%) with 24 weeks of treatment and 82% (47/57; 95% CI 70-91%) with 12 weeks. For HCV genotype 1 and 2 infected patients, the SVR12 rates with 24 weeks of treatment were 98% and 92%, respectively. In both treatment groups, SVR12 rates in HCV genotype 1 patients were statistically superior to a historical control rate of 50% (p < 0.001). For patients with NS5A RASs at baseline, 85% (46/54) in the 12-week group and 96% (54/56) in the 24-week group achieved SVR12. The most common adverse events were upper respiratory tract viral infection, anemia, and headache. Three (2.6%) patients discontinued treatment because of adverse events. CONCLUSION: Sofosbuvir-velpatasvir plus ribavirin was highly effective and well tolerated in Japanese patients who previously failed a DAA-based regimen. Baseline NS5A RASs did not affect treatment outcomes.

Sofosbuvir + velpatasvir + voxilaprevir for the treatment of hepatitis C infection.

INTRODUCTION: Hepatitis C is a disease with a significant global impact. Over the last several years, the treatment of the disease has been revolutionized. Therapy has transformed over the last several years with the approval of second generation direct acting antivirals, and currently utilized medications for the treatment of hepatitis C are significantly more efficacious with better safety profiles than previously approved treatments. Treatment for individuals who have failed therapy on direct acting antivirals has, until recently, been complex and difficult to treat, but the approval of sofosbuvir/velpatasvir/voxilaprevir represents a new therapeutic option for these individuals. Areas covered: Sofosbuvir/velpatasvir/voxilaprevir is a recently approved therapeutic combination for the treatment of hepatitis C. This article reviews the studies leading to the approval of the combination, and its efficacy and safety profile. Expert opinion: Sofosbuvir/velpatasvir/voxilaprevir fills one of the previously unfilled niches for the treatment of hepatitis C, that of the treatment of individuals who have failed therapy with resistant virus. With the filling of this niche, there appears to be a general slowing of the development of new therapeutics. Although understandable, in the long term, there are considerable risks associated with the decreased development of new drugs to treat hepatitis C.

Sofosbuvir plus ribavirin with or without peginterferon for the treatment of hepatitis C virus: Results from a phase 3b study in China.

BACKGROUND AND AIM: Sofosbuvir is a nucleotide analog inhibitor of the hepatitis C virus (HCV) NS5B RNA polymerase with pangenotypic potency. This phase 3b study evaluated the safety and efficacy of sofosbuvir + ribavirin ± peginterferon in Chinese patients infected with HCV genotype 1, 2, 3, or 6. METHODS: Patients with genotype 1 or 6 received sofosbuvir + peginterferon/ribavirin for 12 weeks or sofosbuvir + ribavirin for 24 weeks, depending on prior treatment and interferon eligibility. Patients with genotype 2 or 3 received sofosbuvir + ribavirin for 12 or 24 weeks, respectively. The primary endpoint was sustained virologic response at 12 weeks after the end of treatment (SVR12). RESULTS: Of 389 patients, 42% had genotype 1, 16% genotype 2, 32% genotype 3, and 9% genotype 6. Half were male, 58% were treatment-naïve, and 15% had cirrhosis. SVR12 rates for patients receiving 12 weeks of sofosbuvir + peginterferon/ribavirin were 94% (95% confidence interval [CI], 87-98%) for HCV genotype 1 and 97% (95% CI, 84-100%) for genotype 6. SVR12 rates for those receiving sofosbuvir + ribavirin for 24 weeks were 95% (95% CI, 87-99%) for genotype 1, 100% (95% CI, 40-100%) for genotype 6, and 95% (95% CI, 90-98%) for genotype 3. For genotype 2 patients receiving sofosbuvir + ribavirin for 12 weeks, the SVR12 rate was 92% (95% CI, 83-97%). Twenty patients (5%) relapsed. Ten (3%) experienced serious adverse events. Three (< 1%) discontinued treatment because of adverse events, of whom one died because of treatment-unrelated adverse events. CONCLUSIONS: Sofosbuvir-based regimens were highly effective and safe in Chinese patients with HCV genotype 1, 2, 3, or 6, suggesting sofosbuvir could serve as the backbone for HCV treatment in China irrespective of genotype.

Efficacy and safety of ledipasvir/sofosbuvir with ribavirin in chronic hepatitis C patients who failed daclatasvir/asunaprevir therapy: pilot study.

BACKGROUND: In Japan, daclatasvir (DCV) and asunaprevir (ASV) therapy was the first IFN-free treatment to be approved, and thousands of patients have since been successfully treated, with an SVR rate of around 90%. The converse, however, is that around 10% of patients fail to achieve viral eradication and must be retreated using a different approach. This study is to evaluate treatment efficacy of ledipasvir/sofosbuvir and ribavirin in patients who failed to respond to DCV and ASV therapy. METHODS: Thirty patients were treated with 12 weeks of ledipasvir/sofosbuvir and ribavirin. We evaluated the rate of sustained virological response 12 weeks after the end of treatment (SVR12) and examined the incidence of adverse events during ledipasvir/sofosbuvir and ribavirin treatment. NS5A and NS5B resistance-associated variants (RAVs) in treatment failure cases were examined. RESULTS: The overall SVR12 rate was 86.7% (26/30). Large decreases in mean log10 HCV RNA levels were observed in patients without cirrhosis, and the SVR12 rate for these patients was 100% (12/12). In cases of cirrhosis, SVR12 rate was 72.2% (13/18). The common factors in treatment failure cases were the presence of liver cirrhosis and both NS5A L31M/I and Y93H RAVs. The frequency of RAVs did not change before and after treatment among patients who relapsed. CONCLUSION: Ledipasvir/sofosbuvir with ribavirin is an effective retreatment option for patients with chronic hepatitis C who failed to respond to prior daclatasvir and asunaprevir therapy.

Protease Inhibitor Resistance Remains Even After Mutant Strains Become Undetectable by Deep Sequencing.

BACKGROUND: Although treatment-emergent NS3/4A protease inhibitor (PI)-resistant variants typically decrease in frequency after cessation of PI therapy in patients with chronic hepatitis C virus (HCV) infection, HCV susceptibility to PIs in patients who have not responded to previous PI therapy has not been addressed. METHODS: Patients with chronic HCV genotype 1 infection were treated either with simeprevir plus interferon or with daclatasvir plus asunaprevir. Frequencies of drug-resistant mutations among patients with treatment failure were analyzed by deep sequencing. Human hepatocyte chimeric mice were injected with serum samples obtained from either treatment-naive patients or nonresponders to treatment with daclatasvir plus asunaprevir and then were treated with simeprevir and sofosbuvir. RESULTS: Virological response to daclatasvir plus asunaprevir treatment was significantly lower in patients with simeprevir treatment failure as compared to those without previous treatment. Deep-sequencing analysis showed that the frequency of PI treatment-emergent NS3-D168 mutations gradually decreased and were completely replaced by wild-type genes after cessation of therapy. However, mice injected with serum obtained from a patient with PI treatment failure rapidly developed NS3-D168 mutations at significantly higher frequencies following either simeprevir or sofosbuvir treatment. CONCLUSIONS: The virological response to daclatasvir plus asunaprevir treatment was low in patients with simeprevir treatment failure. PI resistance remains even after disappearance of mutant strains by deep sequencing.

Successful Re-treatment of Hepatitis C Virus in Patients Coinfected With HIV Who Relapsed After 12 Weeks of Ledipasvir/Sofosbuvir.

UNLABELLED: We assessed the efficacy and safety of ledipasvir/sofosbuvir plus ribavirin for 24 weeks in 9 human immunodeficiency virus/hepatitis C virus-coinfected patients who relapsed after receiving 12 weeks of treatment with ledipasvir/sofosbuvir. Eight of 9 (89%) achieved sustained virologic response 12 weeks after the end of treatment. One patient relapsed at posttreatment week 4. These results suggest an effective salvage therapy for patients for whom direct-acting antiviral treatment has failed. CLINICAL TRIALS REGISTRATION: NCT02073656.

Efficacy of Sofosbuvir and Daclatasvir in Patients With Fibrosing Cholestatic Hepatitis C After Liver Transplantation.

BACKGROUND & AIMS: Fibrosing cholestatic hepatitis (FCH) is a life-threatening disorder that develops in patients with recurrent hepatitis C virus (HCV) infection after liver transplantation. Until recently, therapeutic options have been limited. We evaluated the efficacy and safety of sofosbuvir- and daclatasvir-based regimens. METHODS: We analyzed data from 23 patients with FCH who participated in a prospective cohort study in France and Belgium of the effects of antiviral agents in patients with recurrence of HCV infection after liver transplantation, from October 2013 through April 2014. Most of the patients had genotype 1 infections that had not responded to previous treatment; 4 patients also were infected with human immunodeficiency virus. Eight patients (37%) had ascites and 15 patients (65%) had bilirubin levels greater than 100 mmol/L; their median serum level of HCV RNA was 7 log IU/mL. The median time between transplantation and treatment initiation was 5 months. Subjects were given either sofosbuvir and daclatasvir (n = 15) or sofosbuvir and ribavirin (n = 8) for 24 weeks. The primary outcome was complete clinical response (survival without re-transplantation, bilirubin level <34 µmol/L, and no ascites or hepatic encephalopathy 36 weeks after treatment began). RESULTS: All patients survived, without re-transplantation, until week 36. Rapid and dramatic improvements in clinical status were observed. The patients' median bilirubin concentration decreased from 122 µmol/L at baseline to a normal value at week 12 of treatment. Twenty-two patients (96%) had a complete clinical response at week 36. Despite the low rate of rapid virologic response, 22 patients (96%) achieved a sustained virologic response at week 12. The only relapse of HCV infection occurred in a patient with human immunodeficiency virus infection who received sofosbuvir and ribavirin. Tolerance was satisfactory, with no grade 3 or 4 adverse events related to sofosbuvir or daclatasvir and no significant interactions among drugs. CONCLUSIONS: Sofosbuvir therapy with daclatasvir or ribavirin leads to major clinical improvement and high rates of sustained virologic response at week 12 in most patients with recurrence of HCV infection and FCH after liver transplantation. ClinicalTrial.gov no: NCT01944527.

Working together to tackle HCV infection: ombitasvir/paritaprevir/ritonavir and dasabuvir combination.

An estimated 184 million people worldwide have hepatitis C virus (HCV) infection. Chronic infection can ultimately result in liver cirrhosis and hepatic failure. Eradication of the virus by antiviral treatment can hinder the development of the aforementioned complications. Historically, the combination therapy of PEGylated interferon/ribavirin was considered the standard-of-care therapy for HCV. Such therapy did not demonstrate satisfactory cure rates and had significant side effects that precluded its widespread use among HCV patients. In view of this situation, scientific advances have led to the development of new interferon-free regimens that are better tolerated, more effective and with shorter duration of therapy. One of the newest members of this family is the all-oral regimen (ombitasvir/paritaprevir/ritonavir co-packaged with dasabuvir) that has recently received FDA approval for the treatment of adult patients with genotype 1 HCV infection, including those with compensated cirrhosis. This new combination was found to be safe and well tolerated with high rates of sustained virologic response of up to 100%. An overview of the current knowledge about this regimen is reviewed herein.

Changing the face of hepatitis C management - the design and development of sofosbuvir.

The availability of direct-acting antiviral (DAA) therapy has launched a new era in the management of chronic hepatitis C. Sofosbuvir, a uridine nucleotide analog that inhibits the hepatitis C RNA-dependent RNA polymerase, is the backbone of chronic hepatitis C therapy. Acting at the catalytic site of the polymerase, sofosbuvir is highly potent in suppressing viral replication and has a high genetic barrier to resistance. Sofosbuvir is effective across all hepatitis C genotypes, and is a mainstay of interferon-free combination therapy. In Phase II and III studies, genotype 1 patients who took sofosbuvir in combination with another DAA such as the NS3-4A protease inhibitor, simeprevir, or the NS5A replication complex inhibitors, ledipasvir or daclatasvir, achieved a sustained virologic response rate of over 90%. Harvoni(®), a combination tablet of sofosbuvir and ledipasvir, dosed once daily is recommended for 24 weeks for treatment-experienced genotype 1 patients with cirrhosis, but 12 weeks of therapy is sufficient for all other populations. While genotype 2 (12 weeks or 16 weeks) and treatment-naïve genotype 3 patients (24 weeks) have excellent response rates with sofosbuvir and ribavirin, treatment-experienced cirrhotic genotype 3 patients may need the addition of another DAA such as daclatasvir. Sofosbuvir is efficacious in special populations such as HIV-hepatitis C virus-coinfected patients and liver transplant recipients and has already made a profound impact in these groups. Since it is renally eliminated, patients with advanced kidney disease or on dialysis must await dosing recommendations. Sofosbuvir-based regimens appear to be well tolerated with headache and fatigue being the most common side effects. The opportunity to cure patients with hepatitis C with sofosbuvir combination therapy is likely to change the future for our patients, particularly if the emphasis shifts to identifying those patients unaware that they are infected and providing affordable access to treatment.

A randomized, placebo-controlled study of the NS5B inhibitor beclabuvir with peginterferon/ribavirin for HCV genotype 1.

Beclabuvir is a potent, non-nucleoside inhibitor of the HCV NS5B RNA polymerase, with nanomolar activity against HCV genotypes 1, 3, 4, 5 and 6 in vitro. This study evaluated the efficacy and safety of beclabuvir, in combination with peginterferon alfa-2a (pegIFN) and ribavirin (RBV), in HCV genotype 1. In this randomized (1:1:1), double-blinded, placebo-controlled, dose-ranging phase 2a study, 39 treatment-naive patients chronically infected with HCV genotype 1 were treated for 48 weeks with beclabuvir (75 mg or 150 mg) plus pegIFN (180 µg) and RBV (1000 mg/day [<75 kg] or 1200 mg/day [≥ 75 kg]) vs pegIFN/RBV alone. The primary efficacy endpoint of extended rapid virologic response (undetectable HCV RNA at treatment weeks 4 and 12) was achieved by 76.9% (10/13) of patients receiving beclabuvir 75 mg and 38.5% (5/13) receiving beclabuvir 150 mg vs 0% receiving pegIFN/RBV alone. Higher response rates were observed among patients receiving beclabuvir 75 mg for all secondary efficacy endpoints, including sustained virologic response at follow-up weeks 12 or 24. Three patients experienced virologic breakthrough on treatment, all in the beclabuvir 150-mg treatment group. Beclabuvir was well tolerated at both doses, with the most commonly observed adverse events (headache, fatigue, nausea, decreased appetite, irritability, depression and insomnia) consistent with those observed with pegIFN/RBV. In conclusion, beclabuvir was both effective and well tolerated when administered in combination with pegIFN/RBV for the treatment of chronic HCV GT 1, supporting the study of beclabuvir as part of an all-oral regimen for HCV GT1.

Sofosbuvir and ribavirin for treatment of compensated recurrent hepatitis C virus infection after liver transplantation.

BACKGROUND & AIMS: Interferon alfa-based regimens used to treat recurrent hepatitis C virus (HCV) infection after liver transplantation are poorly tolerated, associated with generally modest efficacy, and can interact with immunosuppressive agents. We evaluated the efficacy and safety of an interferon-free regimen of the nucleotide polymerase inhibitor sofosbuvir combined with ribavirin for 24 weeks in treating post-transplantation HCV infection. METHODS: In a prospective, multicenter, open-label pilot study, we enrolled patients with compensated recurrent HCV infection of any genotype after a primary or secondary liver transplantation. All patients received 24 weeks of sofosbuvir 400 mg daily and ribavirin starting at 400 mg daily, which was adjusted according to creatinine clearance and hemoglobin values. The primary end point was sustained virologic response 12 weeks after treatment. RESULTS: Of the 40 patients enrolled and treated, 78% were male, 85% were white, 83% had HCV genotype 1, 40% had cirrhosis (based on biopsy), and 88% had been previously treated with interferon. Sustained virologic response 12 weeks after treatment was achieved by 28 of 40 patients (70%; 90% confidence interval: 56%-82%). Relapse accounted for all cases of virologic failure. No patients had detectable viral resistance during or after treatment. The most common adverse events were fatigue (30%), diarrhea (28%), and headache (25%). In addition, 20% of the subjects experienced anemia. Two patients discontinued study treatment because of adverse events, which were considered unrelated to study treatment. No deaths, graft losses, or episodes of rejection occurred. No interactions with any concomitant immunosuppressive agents were reported. CONCLUSIONS: Sofosbuvir and ribavirin combination therapy for 24 weeks is an effective and well-tolerated interferon-free treatment for post-transplantation HCV infection. EudraCT, Number: 2012-002417-19; ClinicalTrials.gov, Number: NCT01687270.

Sofosbuvir, a novel nucleotide analogue inhibitor used for the treatment of hepatitis C virus.

OBJECTIVE: To provide an overview of a novel anti-hepatitis C agent, sofosbuvir. KEY FINDINGS: Sofosbuvir is a novel nucleotide analogue inhibitor of hepatitis C virus (HCV) NS5B polymerase that has recently been approved by the Federal Drug Administration for the treatment of HCV genotypes 1, 2, 3 or 4 in a variety of patients. The emergence of such a novel treatment provides benefit to previously untreated genotypes and patient populations, with little chance of promoting significant viral resistance. Excellent sustained virologic response rates 12 weeks after the end of treatment (SVR12) were seen in phase II and III clinical trials when sofosbuvir was used with ribavirin. Even more promising are the results from phase II and III clinical trials that evaluated sofosbuvir in combination with other oral direct acting antivirals (DAAs). Data with sofosbuvir in the hepatitis C virus (HCV)/HIV coinfected and in the pre- and post-transplantation populations are still emerging. The drug was very well tolerated in clinical studies, with the most common adverse events of headache, nausea and fatigue. SUMMARY: Overall, sofosbuvir presents a new and effective treatment option for HCV-infected patients.

Preparation and biological evaluation of 1'-cyano-2'-C-methyl pyrimidine nucleosides as HCV NS5B polymerase inhibitors.

The first synthesis of 1'-cyano-2'-C-methyl pyrimidine nucleosides is described. Anti-HCV activity of these nucleosides and their nucleotide phosphoramidate prodrugs was assessed and compared to the 1'-unsubstituted counterparts and to the related 1'-cyano-2'-C-methyl C-nucleoside parent of GS-6620.

Sofosbuvir: A Nucleotide NS5B Inhibitor for the Treatment of Chronic Hepatitis C Infection.

OBJECTIVE: To review the use of sofosbuvir for the treatment of chronic hepatitis C virus (HCV). DATA SOURCES: Review and nonreview articles were identified through MEDLINE (1996-April 2014), citations of articles, and meeting abstracts using keywords, including NS5B polymerase inhibitor, GS-7977, sofosbuvir, direct-acting antiviral (DAA), and others. STUDY SELECTION AND DATA EXTRACTION: Phase 1, 2, and 3 studies describing dose-ranging potential, pharmacokinetics, efficacy, safety, and tolerability of sofosbuvir were identified. DATA SYNTHESIS: Sofosbuvir is an NS5B polymerase inhibitor that was approved for use by the Food and Drug Administration in December 2013 for the treatment of chronic HCV in combination with pegylated interferon (peg-IFN) and ribavirin (RBV) for genotype 1. Additionally, it has been evaluated with other oral DAAs, such as simeprevir and others in the pipeline. It is not recommended as monotherapy because of lower sustained virological response (SVR) rates in clinical studies. Most of the treatment regimens are 12 weeks in duration; however, certain populations require a longer duration. Sofosbuvir has activity against all 6 genotypes, although most clinical trials evaluated genotypes 1 to 3. Sofosbuvir has a favorable safety and tolerability profile, making it a recommended first-line agent for chronic HCV infection. CONCLUSION: In clinical trials, 12 weeks of sofosbuvir with concomitant peg-IFN and RBV therapy in treatment-naïve and experienced HCV genotype 1 patients resulted in SVR rates of >90%. An all-oral regimen of sofosbuvir and RBV is highly effective for genotype 2 and 3 patients. Sofosbuvir was found to be tolerable with minimal adverse effects (AEs), and no treatment discontinuations occurred secondary to drug related AEs..

Classification of HCV NS5B polymerase inhibitors using support vector machine.

Using a support vector machine (SVM), three classification models were built to predict whether a compound is an active or weakly active inhibitor based on a dataset of 386 hepatitis C virus (HCV) NS5B polymerase NNIs (non-nucleoside analogue inhibitors) fitting into the pocket of the NNI III binding site. For each molecule, global descriptors, 2D and 3D property autocorrelation descriptors were calculated from the program ADRIANA.Code. Three models were developed with the combination of different types of descriptors. Model 2 based on 16 global and 2D autocorrelation descriptors gave the highest prediction accuracy of 88.24% and MCC (Matthews correlation coefficient) of 0.789 on test set. Model 1 based on 13 global descriptors showed the highest prediction accuracy of 86.25% and MCC of 0.732 on external test set (including 80 compounds). Some molecular properties such as molecular shape descriptors (InertiaZ, InertiaX and Span), number of rotatable bonds (NRotBond), water solubility (LogS), and hydrogen bonding related descriptors performed important roles in the interactions between the ligand and NS5B polymerase.

Emerging therapies for chronic hepatitis C virus.

Current hepatitis C virus (HCV) therapies are associated with significant adverse events and less-than-ideal sustained virologic response (SVR) rates in genotype 1 patients. The current standard of care, a combination of pegylated interferon and ribavirin, will likely remain a key component of the treatment regimen for years to come. Multiple new drugs are currently in development and are expected to be approved for use in the United States and/or European Union by 2011 at the earliest. Future therapies will include novel interferons, ribavirin analogues, NS3 HCV protease inhibitors, NS5b HCV polymerase inhibitors, cyclophilin inhibitors, and other novel agents. There is hope that multiple new drugs will be approved over the following 4-10 years to provide alternative treatment choices, improved SVR rates, and reductions in adverse events. However, a number of barriers must be overcome prior to the acceptance of these drugs, involving, but not limited to, their toxicity, viral resistance, optimal dose, duration, and their efficacy and safety in patients with unmet needs.