Clinical pharmacokinetics of the nicotinic channel modulator dexmecamylamine (TC-5214) in subjects with various degrees of renal impairment

Efficacy of Sofosbuvir and Velpatasvir Combination in the Treatment of Hepatitis C Virus (HCV) in Chronic Kidney Disease (CKD) Patients

Background Hepatitis C virus (HCV) infection is still common in patients with chronic renal failure, even those on maintenance dialysis. A bidirectional association exists between HCV infection and chronic renal disease. Objective To assess the efficacy of sofosbuvir and velpatasvir combination in the treatment of chronic HCV in chronic kidney disease (CKD) patients. Methodology This descriptive, cross-sectional study was undertaken at the departments of Gastroenterology and Nephrology Lady Reading Hospital, Peshawar, from April 7, 2021, to October 7, 2021. Patients with chronic HCV and chronic renal disease at stage 4 or 5 were included while patients with decompensated cirrhosis liver, hepatoma, hepatitis B virus/HCV (HBV/HCV) coinfection, and post liver transplant patients were excluded. HCV infection was diagnosed based on detectable HCV ribonucleic acid (HCV RNA) by PCR (polymerase chain reaction). In contrast, CKD was diagnosed based on the Kidney Disease Improving Global Outcomes (KDIGO) criteria for CKD. Sofosbuvir 400 mg orally daily and velpatasvir 100 mg orally with meals were given daily for 12 weeks. Effectiveness was defined as negative HCV RNA by PCR 12 weeks after treatment completion called sustained virological response rate 12 weeks after treatment completion (SVR12). Results A total of 73 patients including 67 (91.78%) males and six (8.22%) females between the ages of 20 years and 70 years were included in this study. The mean age of the participants was 48.77±8.0 years. Twelve weeks after the treatment completion, 69 (94.52%) had negative HCV RNA, whereas four (5.48%) patients had detectable HCV RNA. Conclusion It can be concluded from our study that a fixed-dose combination of sofosbuvir 400 mg and velpatasvir 100 mg is quite effective and recommended for treating chronic hepatitis C infection in patients with chronic renal disease in our local setup.

Sofosbuvir-based hepatitis C therapies in patients with chronic and end-stage kidney disease

Sofosbuvir (SOF), a nucleotide inhibitor of the hepatitis C virus (HCV) polymerase, is a component of several all-oral HCV therapies. GS-331007, SOF's predominant metabolite, is renally eliminated and accumulates 5- to 20-fold in patients with advanced chronic kidney disease (CKD) or undergoing hemodialysis (HD), respectively. Preclinical data did not determine whether these exposures represented a risk for toxicity. Therefore subjects with advanced CKD were not included in registrational studies and SOF was not initially approved for use in advanced CKD. Nevertheless, after initial licensing, off-label use of SOF at full or reduced doses was reported in patients with kidney disease. Two clinical trials of SOF-containing therapies were conducted in patients with end-stage kidney disease, demonstrating safety and efficacy. These led to expanded US Food and Drug Administration approval in 2019 for the use of SOF-containing regimens in patients with advanced CKD, including dialysis dependence. Even so, given the availability of protease inhibitor-containing direct-acting antiviral regimens, there was a reluctance by some practitioners to use SOF-containing regimens in moderate to severe kidney disease. Here we review the existing data on SOF's pharmacokinetics, toxicology, efficacy and safety in patients with kidney disease. Data from both clinical trials and real-world practice settings indicate that in patients with moderate to severe kidney disease, full-dose SOF-based regimens have high rates of efficacy and acceptable safety and tolerability profiles, without increased risk for cardiac adverse events or clinically meaningful changes in kidney function. SOF-based regimens are safe and effective in patients who have moderate to severe kidney disease, including those undergoing HD.

Pan-genotypic direct-acting antivirals for patients with hepatitis C virus infection and chronic kidney disease stage 4 or 5

Hepatitis C virus (HCV) infection is a major health problem with significant clinical and economic burdens in patients with chronic kidney disease (CKD) stage 4 or 5. Current guidelines recommend pan-genotypic direct-acting antivirals (DAAs) to be the first-line treatment of choice for HCV. This review summarizes the updated knowledge regarding the epidemiology, natural history, public health perspectives of HCV in patients with CKD stage 4 or 5, including those on maintenance dialysis, and the performance of pan-genotypic DAAs in these patients. The prevalence and incidence of HCV are much higher in patients with CKD stage 4 or 5 than in the general population. The prognosis is compromised if HCV patients are left untreated regardless of kidney transplantation (KT). Following treatment-induced HCV eradication, patient can improve the health-related outcomes by maintaining a long-term aviremic state. The sustained virologic response (SVR₁₂) rates and safety profiles of pan-genotypic DAAs against HCV are excellent irrespective of KT. No dose adjustment of pan-genotypic DAAs is required across CKD stages. Assessing drug–drug interactions (DDIs) before HCV treatment is vital to secure on-treatment safety. The use of prophylactic or preemptive pan-genotypic DAAs in HCV-negative recipients who receive HCV-positive kidneys has shown promise in shortening KT waiting time, achieving excellent on-treatment efficacy and safety, and maintaining post-KT patient and graft survival. HCV elimination is highly feasible through multifaceted interventions, including mass screening, treatment scale-up, universal precautions, and post-SVR₁₂ reinfection surveillance.

Sofosbuvir/velpatasvir with or without low-dose ribavirin for patients with chronic hepatitis C virus infection and severe renal impairment

OBJECTIVE

Data regarding the real-world effectiveness and safety of sofosbuvir/velpatasvir (SOF/VEL) with or without low-dose ribavirin (RBV) in patients with chronic hepatitis C virus (HCV) infection and severe renal impairment (RI) are limited. We evaluated the performance of SOF/VEL with or without low-dose RBV in HCV-infected patients with chronic kidney disease stage 4 or 5.

DESIGN

191 patients with compensated (n=181) and decompensated (n=10) liver diseases receiving SOF/VEL (400/100 mg/day) alone and SOF/VEL with low-dose RBV (200 mg/day) for 12 weeks were retrospectively recruited at 15 academic centres in Taiwan. The effectiveness was determined by sustained virological response at off-treatment week 12 (SVR₁₂) in evaluable (EP) and per-protocol populations (PP). The safety profiles were assessed.

RESULTS

The SVR₁₂ rates by EP and PP analyses were 94.8% (95% CI 90.6% to 97.1%) and 100% (95% CI 97.9% to 100%). In patients with compensated liver disease, the SVR₁₂ rates were 95.0% and 100% by EP and PP analyses. In patients with decompensated liver disease, the SVR₁₂ rates were 90.0% and 100% by EP and PP analyses. Ten patients who failed to achieve SVR₁₂ were attributed to non-virological failures. Among the 20 serious adverse events (AEs), none were judged related to SOF/VEL or RBV. The AEs occurring in ≥10% included fatigue (14.7%), headache (14.1%), nausea (12.6%), insomnia (12.0%) and pruritus (10.5%). None had ≥grade 3 total bilirubin or alanine aminotransferase elevations.

CONCLUSION

SOF/VEL with or without low-dose RBV is effective and well-tolerated in HCV-infected patients with severe RI.

An Updated View on the Antiviral Therapy of Hepatitis C in Chronic Kidney Disease

BACKGROUND

Hepatitis C virus infection remains common in patients with chronic kidney disease, including those on maintenance dialysis. The relationship between hepatitis C virus infection and chronic kidney disease is bi-directional; in fact, HCV is both a cause and consequence of chronic kidney disease. According to a systematic review with meta-analysis of observational studies (n = 23 studies) (n = 574,081 patients on long-term dialysis), anti-HCV positive serologic status was an independent and significant risk factor for death in patients with advanced chronic kidney disease on long-term dialysis. The overall estimate for adjusted mortality (all-cause death risk) with HCV was 1.26 (95% CI, 1.18; 1.34) (p < 0.0001). Interferon-based therapies are biased by low efficacy/safety in chronic kidney disease, but the advent of direct-acting antiviral drugs has made a paradigm shift in the treatment of HCV-infection. These medications give interruption of viral replication because they target specific non-structural viral proteins; four classes of DAAs exist-NS3/4A protease inhibitors, NS5A inhibitors, NS5B nucleoside and non-nucleoside polymerase inhibitors. All-oral, interferon-free, ribavirin-free combinations of DAAs are now available.

AIM

The goal of this narrative review is to report the available treatment options for HCV in advanced chronic kidney disease.

METHODS

We have made an extensive review of the medical literature and various research engines have been adopted.

RESULTS

Some combinations of DAAs are currently recommended for HCV in advanced CKD (including patients on maintenance dialysis): elbasvir/grazoprevir; glecaprevir/pibrentasvir; and sofosbuvir-based regimens. Solid evidence, based on registration and "real life" studies supports their efficacy (SVR rates > 90%) and safety even in patients with advanced CKD. No dosage adjustment is necessary and treatment duration is 8-12 weeks. However, recent data highlight that many patients with advanced CKD remain untreated, and numerous barriers to antiviral treatment of HCV still exist. Whether successful antiviral therapy with DAAs will translate into improved survival in the advanced CKD population is another point of future research.

Ledipasvir/Sofosbuvir for 8, 12, or 24 Weeks in Hepatitis C Patients Undergoing Dialysis for End-Stage Renal Disease

INTRODUCTION

We evaluated 8, 12, or 24 weeks of ledipasvir/sofosbuvir in patients with hepatitis C virus and end-stage renal disease undergoing dialysis.

METHODS

Primary efficacy end point was sustained virologic response 12 weeks after treatment. Primary safety end point was treatment discontinuation because of adverse events (AEs).

RESULTS

Ninety-four percent (89/95) achieved sustained virologic response 12 weeks after treatment. Six patients died during treatment (n = 4) or before study completion (n = 2); no deaths were related to treatment. No patients discontinued treatment because of AEs. Thirteen percent had serious AEs; none were related to treatment.

DISCUSSION

Treatment with ledipasvir/sofosbuvir was safe and effective in patients with end-stage renal disease undergoing dialysis.

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-β-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.

Renal safety in 3264 HCV patients treated with DAA-based regimens: Results from a large Italian real-life study

BACKGROUND

Sofosbuvir (SOF)-based regimens have been associated with renal function worsening in HCV patients with estimated glomerular filtration rate (eGFR) ≤ 45 ml/min, but further investigations are lacking.

AIM

To assess renal safety in a large cohort of DAA-treated HCV patients with any chronic kidney disease (CKD).

METHODS

All HCV patients treated with DAA in Lombardy (December 2014-November 2017) with available kidney function tests during and off-treatment were included.

RESULTS

Among 3264 patients [65% males, 67% cirrhotics, eGFR 88 (9-264) ml/min], CKD stage was 3 in 9.5% and 4/5 in 0.7%. 79% and 73% patients received SOF and RBV, respectively. During DAA, eGFR declined in CKD-1 (p < 0.0001) and CKD-2 (p = 0.0002) patients, with corresponding rates of CKD stage reduction of 25% and 8%. Conversely, eGFR improved in lower CKD stages (p < 0.0001 in CKD-3a, p = 0.0007 in CKD-3b, p = 0.024 in CKD-4/5), with 33-45% rates of CKD improvement. Changes in eGFR and CKD distribution persisted at SVR. Baseline independent predictors of CKD worsening at EOT and SVR were age (p < 0.0001), higher baseline CKD stages (p < 0.0001) and AH (p = 0.010 and p < 0.0001, respectively).

CONCLUSIONS

During DAA, eGFR significantly declined in patients with preserved renal function and improved in those with lower CKD stages, without reverting upon drug discontinuation.

A liquid chromatography-tandem mass spectrometry method for simultaneous determination of simeprevir, daclatasvir, sofosbuvir, and GS-331007 applied to a retrospective clinical pharmacological study

A highly sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for simultaneous determination of daclatasvir (DCV), simeprevir (SMV), sofosbuvir (SOF), and its major metabolite GS-331007 in human plasma using stable-isotope-labeled (SIL) analogs as internal standards (IS) to minimize a possible matrix effect. Liquid-liquid extraction (LLE) of the analytes and IS from human plasma was performed using a commercial extraction kit requiring low sample volume (50 μL). The analytes were eluted under a gradient program with mobile phase A (water + 0.1% formic acid) and mobile phase B (methanol + 0.1% formic acid) at a flow-rate of 0.6 mL/min for 10 min. The detection was performed on a Qtrap 5500 triple quadrupole tandem-mass spectrometer using multiple reaction monitoring (MRM) mode via the positive electrospray ionization interface. The method was validated according to the European Medicine Agency (EMA) guidelines over the clinically relevant concentration range of 15.6-2000 ng/mL. The high reproducibility, the low matrix effect associated with the use of SIL-IS, and the need of small sample amounts make this method particularly suited for high-throughput routine analysis. The proposed method was successfully applied to a retrospective clinical pharmacology study involving 67 HIV/HCV co-infected patients treated with a SOF-based therapy. DCV, SMV, SOF, and GS-331007 plasma levels were measured at week 4 of treatment and compared with the patients' clinical and laboratory characteristics. Higher GS-331007 plasma concentrations were observed in female patients compared to males, which can be explained by different anthropometric characteristics between genders. Importantly, patients with high plasma levels of GS-331007 also showed enhanced concentration of DCV and SMV probably due to a specific metabolic/pathological condition. Altogether, our findings indicate that the proposed method is a reliable and accurate new tool for high-throughput screening of large patient cohorts that could be readily used to optimize treatment modalities and reduce drug-related toxicities.

Incidence of Acute Kidney Injury in Patients Coinfected with HIV and Hepatitis C Virus Receiving Tenofovir Disoproxil Fumarate and Ledipasvir/Sofosbuvir in a Real-World, Urban, Ryan White Clinic

Ledipasvir/sofosbuvir (LDV/SOF), an antiviral treatment for hepatitis C virus (HCV), and tenofovir disoproxil fumarate (TDF), an antiretroviral for treating human immunodeficiency virus (HIV), may be coadministered in patients coinfected with these viruses. A drug interaction between LDV and TDF could increase TDF-associated nephrotoxicity rates; however, there is minimal clinical evidence describing acute kidney injury (AKI) rates in this population. This study was conducted at a Ryan White-funded facility in Atlanta, Georgia, that cares for over 5,000 patients with AIDS. This retrospective cohort used chart review to assess occurrence of and risk factors for AKI in HIV/HCV-coinfected patients receiving LDV/SOF and antiretroviral therapy (ART). AKI rates were compared between TDF-containing and non-TDF-containing ART groups according to Kidney Disease Improving Global Outcomes (KDIGO) criteria. Additional evaluated risk factors for AKI included chronic kidney disease and use of boosted protease inhibitor-based ART. In the 117 included patients, the overall incidence of AKI was 27.3%. AKI occurred more frequently in the non-TDF group (13/86, 15.1% vs. 19/31, 61.3%, p < .001). All AKI was KDIGO stage 1. From multivariable logistic regression, the only independent predictor of AKI was treatment with non-TDF relative to TDF (adjusted odds ratio 6.51, 95% confidence interval 2.34-18.10, p < .001). In this real-world cohort of HIV/HCV-coinfected patients, KDIGO-defined AKI was common, but occurred less frequently in patients receiving TDF-based ART. Our study suggests that patients with normal baseline renal function can be safely treated with TDF and LDV/SOF without significant nephrotoxicity if renal function is closely monitored.

Impact of Sofosbuvir-Based Regimens for the Treatment of Hepatitis C After Liver Transplant on Renal Function: Results of a Canadian National Retrospective Study

OBJECTIVES

We assessed the impact of sofosbuvir-based regimens on renal function in liver transplant recipients with recurrent hepatitis C virus and the role of renal function on the efficacy and safety of these regimens.

MATERIALS AND METHODS

In an expanded pan-Canadian cohort, 180 liver transplant recipients were treated with sofosbuvir-based regimens for hepatitis C virus recurrence from January 2014 to May 2015. Mean age was 58 ± 6.85 years, and 50% had F3/4 fibrosis. Patients were stratified into 4 groups based on baseline estimated glomerular filtration rate (calculated by the Modification of Diet in Renal Disease formula): < 30, 30 to 45, 46 to 60, and > 60 mL/min/173 m2. The primary outcome was posttreatment changes in renal function from baseline. Secondary outcomes included sustained virologic response at 12 weeks posttreatment and anemia-related and serious adverse events.

RESULTS

Posttreatment renal function was improved in most patients (58%). Renal function declined in 22% of patients, which was more marked in those with estimated glomerular filtration rate < 30 mL/min/173 m2, advanced cirrhosis (P = .05), and aggressive hepatitis C virus/fibrosing cholestatic hepatitis (P < .05). High rates (80%-88%) of sustained virologic response at 12 weeks posttreatment were seen across all renal function strata. Cirrhotic patients with glomerular filtration rates < 30 mL/min/173 m2 had sustained virologic response rates at 12 weeks posttreatment comparable to the overall patient group. Rates of anemia-related adverse events and transfusion requirements increased across decreasing estimated glomerular filtration rate groups, with notably more occurrences with ribavirin-based regimens.

CONCLUSIONS

Sofosbuvir-based regimens improved overall renal function in liver transplant recipients, with sustained virologic response, suggesting an association of subclinical hepatitis C virus-related renal disease. Sustained virologic response rates at 12 weeks posttreatment (80%-88%) were comparable regardless of baseline renal function but lower in cirrhosis.

Pharmacokinetics, Efficacy, and Safety of Hepatitis C Virus Drugs in Patients with Liver and/or Renal Impairment

Hepatitis C virus (HCV)-infected patients often suffer from liver cirrhosis, which can be complicated by renal impairment. Therefore, in this review we describe the treatment possibilities in HCV patients with hepatic and renal impairment. Cirrhosis alters the structure of the liver, which affects drug-metabolizing enzymes and drug transporters. These modifications influence the plasma concentration of substrates of drugs metabolized/transported by these enzymes. The direct-acting antivirals (DAAs) are substrates of, for example, cytochrome P450 enzymes in the liver. Most DAAs are not studied in HCV-infected individuals with decompensated cirrhosis, and therefore awareness is needed when these patients are treated. Most DAAs are contraindicated in cirrhotic patients; however, patients with a Child-Pugh score of B or C can be treated safely with a normal dose sofosbuvir plus ledipasvir or daclatasvir, in combination with ribavirin. Patients with renal impairment (glomerular filtration rate [GFR] <90 mL/min) or who are dependent on dialysis often tolerate ribavirin treatment poorly, even after dose adjustments. However, most DAAs can be used at the normal dose because DAAs are not renally excreted. To date, grazoprevir plus elbasvir is the preferred DAA regimen in patients with renal impairment as data are pending for sofosbuvir patients with GFR <30 mL/min (as for ledipasvir and velpatasvir). However, sofosbuvir has been used in a small number of patients with severe renal impairment and, based on these trials, we recommend sofosbuvir 400 mg every day when no other DAA regimen is available. Ledipasvir and velpatasvir are not recommended in patients with severe renal impairment.

Clinical Pharmacokinetics and Pharmacodynamics of Ledipasvir/Sofosbuvir, a Fixed-Dose Combination Tablet for the Treatment of Hepatitis C

Ledipasvir/sofosbuvir (Harvoni^®), a fixed-dose combination tablet of an NS5A inhibitor ledipasvir and an NS5B polymerase inhibitor sofosbuvir, is approved in the US, European Union, Canada, and other regions for the treatment of chronic hepatitis C virus infection in adults. Following absorption, ledipasvir reaches maximum plasma concentrations (T _max) 4-4.5 h post-dose and is eliminated with a terminal half-life (t _1/2) of 47 h. Sofosbuvir undergoes intracellular activation to an active triphosphate GS-461203 (not detected in plasma) and ultimately to GS-331007, a predominant circulating metabolite, which is the primary analyte of interest in clinical pharmacology studies. Sofosbuvir is rapidly absorbed and eliminated from plasma (T _max: 0.8-1 h; t _1/2: 0.5 h). The peak plasma concentrations for GS-331007 are achieved between 3.5 and 4 h post-dose; the elimination t _1/2 for GS-331007 is 27 h. Ledipasvir/sofosbuvir exhibits a favorable clinical pharmacology profile; it can be administered once daily without regard to food and does not require dose modification in hepatitis C virus-infected patients with any degree of hepatic impairment or mild to moderate renal impairment. The pharmacokinetic profiles of ledipasvir, sofosbuvir, and GS-331007 (predominant circulating metabolite of sofosbuvir) are not significantly affected by demographic variables; pharmacokinetic/pharmacodynamic analyses reveal no exposure-response relationships for efficacy or safety. The review summarizes the clinical pharmacokinetics, pharmacodynamics, and pharmacokinetic/pharmacodynamic analyses for ledipasvir/sofosbuvir.

Simeprevir and daclatasvir for 12 or 24 weeks in treatment-naïve patients with hepatitis C virus genotype 1b and advanced liver disease

BACKGROUND & AIMS

We investigated the efficacy and safety of simeprevir plus daclatasvir in treatment-naïve patients with chronic, genotype 1b hepatitis C virus infection and advanced liver disease, excluding patients with pre-defined NS5A resistance-associated substitutions.

METHODS

This phase II, open-label, single-arm, multicentre study included patients aged ≥18 years with advanced fibrosis or compensated cirrhosis (METAVIR F3/4). Patients with NS5A-Y93H or L31M/V resistance-associated substitutions at screening were excluded. Simeprevir (150 mg)+daclatasvir (60 mg) once daily was administered for 12 or 24 weeks; treatment could be extended to 24 weeks prior to or at the Week 12 visit. Primary efficacy endpoint was sustained virological response 12 weeks after the end of treatment.

RESULTS

A total of 106 patients were treated; 27% patients were aged >65 years, 39% had cirrhosis, 53% had estimated glomerular filtration rate 30-89 mL/min, 14% had diabetes, and 38% had arterial hypertension. Overall, 42/106 received 12 weeks of treatment and 64/106 received 24 weeks of treatment. Ninety-seven (92%) patients achieved a sustained virological response 12 weeks after the end of treatment. The reasons for failure were viral breakthrough (n=7) at weeks 4-16, early treatment discontinuation (n=1) and viral relapse (n=1). Seventy-four (70%) patients had ≥1 adverse event during treatment, including six (6%) patients with ≥1 serious adverse event. Three (3%) patients discontinued treatment owing to adverse events.

CONCLUSIONS

Simeprevir+daclatasvir demonstrated strong antiviral activity and was well-tolerated in patients with hepatitis C virus genotype 1b infection, advanced liver disease and a high prevalence of comorbidities. However, viral breakthrough occurred in seven patients, making this regimen unsatisfactory.

Efficacy and safety of sofosbuvir-based regimens for treatment in chronic hepatitis C genotype 1 patients with moderately impaired renal function

BACKGROUND/AIMS

Treatment of chronic hepatitis C virus (HCV) infection in patients with chronic kidney disease (CKD) is essential. The availability of sofosbuvir (SOF) has dramatically improved overall HCV cure rates, however there is insufficient data regarding its use in patients with CKD. We evaluated SOF in patients with hepatitis C genotype 1 (G1) and moderately impaired renal function.

METHODS

We retrospectively reviewed all patients treated with a SOF-based regimen from December 2013 through September 2015 at Virginia Mason Medical Center. Data was then collected for HCV G1 patients with stage 3 CKD.

RESULTS

A total of 28 patients with HCV G1 and stage 3 CKD were treated with a SOF-based regimen. Twenty-one patients had stage 3A CKD (estimated glomerular filtration rate [eGFR] 45-60 mL/min/1.73m2) and 7 patients had stage 3B CKD (eGFR 30-45 mL/min/1.73m2). The overall rate of sustained virologic response (SVR) 12 weeks after completion of therapy (SVR12) was 85.7% (24/28). SVR12 in stage 3A CKD patients was 81.0% (17/21) and in stage 3B CKD patients, SVR12 was 100% (7/7). Based on the treatment regimen used, the SVR12 was 81.8% (9/11), 92.3% (12/13), and 75.0% (3/4) for SOF/ledipasvir (LDV), SOF/simeprevir (SIM), and SOF/pegylated interferon (PEG)/ribavirin (RBV), respectively. Greater than 30% reduction eGFR was observed in 4 out of 28 patients.

CONCLUSIONS

SOF-based regimens resulted in high SVR12 rates in patients with moderately impaired renal function. During therapy, HCV patients with CKD should be carefully monitored for worsening renal function.

Sofosbuvir Use in the Setting of End-stage Renal Disease: A Single Center Experience

Background and Aims: Patients with chronic hepatitis C (CHC) and end-stage renal disease (ESRD) who are dialysis-dependent form a unique group, in which safety, tolerability and efficacy of sofosbuvir (SOF)-based direct-acting antivirals (DAAs) need further evaluation. Methods: We performed a retrospective analysis of 14 patients with CHC and ESRD on dialysis who received 15 courses of SOF-based therapy. We evaluated dose escalation to standard-dose SOF in this proof-of-principle experience. Results: Sustained virological response (defined as undetectable viral load at 12 weeks, SVR-12) was achieved in 13 out of the 15 (86.7%) treatment courses. Seven (46.6%) patients received reduced half dose as conservative proof-of-principal to mitigate potential toxicity. In 13 out of 15 treatment courses, patients completed the designated treatment duration. One patient was treated twice and developed SVR-12 with the retreatment. One patient was lost to follow-up and counted as a non-responder. Premature discontinuations were not due to DAA-related adverse effects. There were no reports of severe adverse effects or drug interactions. Conclusion: We treated CHC patients with ESRD using dose escalation to standard-dose SOF in this proof-of-principle experience and achieved SVR rates comparable to general population.

Hepatitis C virus infection

Hepatitis C virus (HCV) is a hepatotropic RNA virus that causes progressive liver damage, which might result in liver cirrhosis and hepatocellular carcinoma. Globally, between 64 and 103 million people are chronically infected. Major risk factors for this blood-borne virus infection are unsafe injection drug use and unsterile medical procedures (iatrogenic infections) in countries with high HCV prevalence. Diagnostic procedures include serum HCV antibody testing, HCV RNA measurement, viral genotype and subtype determination and, lately, assessment of resistance-associated substitutions. Various direct-acting antiviral agents (DAAs) have become available, which target three proteins involved in crucial steps of the HCV life cycle: the NS3/4A protease, the NS5A protein and the RNA-dependent RNA polymerase NS5B protein. Combination of two or three of these DAAs can cure (defined as a sustained virological response 12 weeks after treatment) HCV infection in >90% of patients, including populations that have been difficult to treat in the past. As long as a prophylactic vaccine is not available, the HCV pandemic has to be controlled by treatment-as-prevention strategies, effective screening programmes and global access to treatment.

Efficacy and safety of sofosbuvir-based regimens in chronic hepatitis C patients on dialysis

INTRODUCTION

Patients with end-stage renal disease (ESRD) have poor treatment tolerance and outcome to interferon-based regimens. Sofosbuvir-based regimens have improved treatment success in chronic hepatitis C. There is limited data in ESRD patients as sofosbuvir is excreted by the kidney. Several small studies have shown good results.

METHODS

Sixteen consecutive patients of ESRD (on dialysis) and chronic hepatitis C were treated with sofosbuvir-based regimens as they were prospective kidney transplantation recipients, at a tertiary care center in north India. Sofosbuvir was given 400 mg on alternate days. Data is shown as number, mean (SD), and median (range).

RESULTS

Sixteen patients (12 males) aged 45±12 years received sofosbuvir-based treatment. These patients were on hemodialysis from 10 (2-48) months. Eleven of these patients had genotype 1, four had genotype 3, and one had genotype 4 infection; baseline RNA was 7 (5-8) log. The following treatment regimens were used: sofosbuvir, ribavirin, and low dose peginterferon (n = 8; 6 genotype 1 and one each had genotype 3 and 4); sofosbuvir and daclatasvir (n = 7); sofosbuvir, ribavirin, and daclatasvir (n = 1). Ten patients achieved end of treatment response and 8 (80%) of these achieved sustained virological response at 12 weeks (SVR12); six are on treatment. Two patients with genotype one (including one with cirrhosis) had relapse. Seven patients needed blood transfusion; interferon was stopped in one due to thrombocytopenia. Fatigue was present in 4 patients.

CONCLUSION

Sofosbuvir-based regimens can be used in ESRD patients on dialysis with good efficacy.

Pharmacokinetic drug evaluation of velpatasvir plus sofosbuvir for the treatment of hepatitis C virus infection

INTRODUCTION

The fixed-dose combination therapy of sofosbuvir (SOF) plus velpatasvir (VEL) is the first pangenotypic, direct-acting antiviral (DAA), single-treatment regimen (STR) for the treatment of hepatitis C virus (HCV) infection to be commercialized. It is approved for the treatment of HCV genotypes 1, 2, 3, 4, 5, and 6. Following approval in 2016, new pharmacokinetic and pharmacodynamic data were reported, which led to important clinical applications. Areas covered: This review provides a summary of the pharmacokinetics, pharmacodynamics, efficacy and safety of SOF/VEL therapy for treatment of HCV infection. The topics covered include data regarding the drug's absorption, distribution, metabolism, excretion and antiviral activity strategies, such as clinical dose selection and treatment duration. Expert opinion: This novel combination therapy containing 400 mg of SOF plus 100 mg of VEL, taken orally, once daily, with or without food, has an excellent pharmacokinetic and pharmacodynamic profile. SOF/VEL achieved very high rates of sustained virological response in treatment-naive and treatment-experienced patients with chronic HCV genotype 1-6 infection, including those with compensated cirrhosis or HIV-1 co-infection.

Managing drug-drug interactions with new direct-acting antiviral agents in chronic hepatitis C

Several direct-acting antiviral agents (DAAs) have marketing authorization in Europe and in the USA and have changed the landscape of hepatitis C treatment: each DAA has its own metabolism and drug-drug interactions (DDIs), and managing them is a challenge. To compile the pharmacokinetics and DDI data of the new DAA and to provide a guide for management of DDI. An indexed MEDLINE search was conducted using the keywords: DAA, hepatitis C, simeprevir, daclatasvir, ledipasvir, sofosbuvir, 3D regimen (paritaprevir/ritonavir, ombitasvir, dasabuvir), DDI and pharmacokinetics. Data were also collected from hepatology, and infectious disease and clinical pharmacology conferences abstracts. Food can play a role in the absorption of DAAs. Most of the interactions are linked to metabolism (cytochrome P450-3 A4 [CYP3A4]) or hepatic and/or intestinal transporters (organic anion-transporting polypeptide and P-glycoprotein [P-gp]). To a lesser extent other pathways can be involved such as breast cancer resistance protein transporter or UDP-glucuronosyltransferase metabolism. DDI are more likely to occur with 3D regimen, daclatasvir, simeprevir and ledipasvir, as they are all both substrates and inhibitors of P-gp and/or CYP3A4, than with sofosbuvir. They can increase concentrations of coadministered drugs and their concentrations may be influenced by P-gp or CYP3A4 inducers or inhibitors. Overdosage or low dosage can be encountered with potent inducers or inhibitors of CYP3A4 or drugs with a narrow therapeutic range. The key to interpret DDI data is a good understanding of the pharmacokinetic profiles of the drugs involved. Their ability to inhibit CYP450-3A4 and transporters (hepatic and/or intestinal) can have significant clinical consequences.

Sofosbuvir plus daclatasvir with or without ribavirin for chronic hepatitis C infection: Impact of drug concentration on viral load decay

BACKGROUND

Sofosbuvir (SOF) plus daclatasvir (DCV) with or without ribavirin is one of the currently recommended treatment option for chronic hepatitis C.

AIMS

Our objectives were to identify factors associated with SOF/DCV plasma concentrations [C] variations and to evaluate their impact on viral kinetics.

METHODS

130 consecutive HCV patients initiating SOF/DCV therapy with or without ribavirin were enrolled. Clinical, biological, virological and pharmacological data were collected at baseline, at week 4, 8, 12, and 24 of therapy and 12 weeks after the end of therapy.

RESULTS

Mean age was 57 years, 68% of patients were males, 69% were infected by HCV genotype 1 and cirrhosis was observed in 76% of patients. Multivariate analysis showed that higher SOF [C] and DCV [C] during treatment were associated with eGFR impairment and absence of cirrhosis. We found a significant correlation between the magnitude of HCV viral load decrease from day 0 to week 4 and a higher SOF [C] at week 4 (p=0.032) and a higher DCV [C] at week 8 (p=0.013).

CONCLUSIONS

Pharmacological monitoring showed significant associations between elevated SOF or DCV [C] and absence of cirrhosis, decreased eGFR and viral load decrease during the first month of treatment.

Pharmacokinetics, safety and efficacy of a full dose sofosbuvir-based regimen given daily in hemodialysis patients with chronic hepatitis C

BACKGROUND & AIMS

Hepatitis C virus (HCV) infection is an independent risk factor for chronic kidney disease and leads to faster liver disease progression in patients requiring hemodialysis than in those with normal renal function. Little is known about the use of a sofosbuvir-containing regimen for infected patients on hemodialysis. We aimed to describe the pharmacokinetics, safety and efficacy of sofosbuvir in 2 dosing regimens and associated antiviral agents in HCV-infected patients requiring hemodialysis.

METHODS

Multicenter, prospective and observational study of patients receiving sofosbuvir, 400mg once daily (n=7) or 3 times a week (n=5), after hemodialysis with simeprevir, daclatasvir, ledipasvir or ribavirin was conducted. Drug plasma concentrations were determined by liquid chromatography-tandem mass spectrometry before and after a 4h hemodialysis and 1.5h after last drug intake at the end of hemodialysis.

RESULTS

Plasma concentrations of sofosbuvir or its inactive metabolite sofosbuvir-007 did not accumulate with either regimen between hemodialysis sessions or throughout the treatment course. Sofosbuvir-007 extraction ratio (52%) was consistent with historical data. In one patient receiving the once daily regimen, sofosbuvir-007 half-life was slightly higher (38h) than for patients with normal renal function receiving a full dose. Hemodialysis did not remove any other associated anti-HCV agents. Clinical and biological tolerance was good for all patients. Two relapses occurred with the 3 times a week regimen and none with the once daily.

CONCLUSIONS

A regimen including sofosbuvir, 400mg once daily, could be proposed for HCV-infected patients requiring hemodialysis and should be associated with close clinical, biological, cardiovascular, and therapeutic drug monitoring.

LAY SUMMARY

Hepatitis C Virus (HCV) infection in hemodialysis patients is prevalent and aggressive. Effective anti-HCV treatment in these patients may stabilize their renal disease. However, sofosbuvir, the cornerstone of most anti-HCV-containing regimens, should not be administered to these patients until more data is available. In this pharmacokinetic study, sofosbuvir full dose (400mg once daily) administered every day with another direct antiviral agent did not accumulate in hemodialysis patients and was safe and effective.

Review article: safety and tolerability of direct-acting anti-viral agents in the new era of hepatitis C therapy

BACKGROUND

Direct-acting anti-virals (DAAs) licensed to treat chronic HCV infection have revolutionised treatment algorithms by drastically mitigating side effects while enhancing efficacy relative to interferon-based therapy.

AIM

To review adverse events (AEs) uniquely associated with DAA therapy across a broad spectrum of patient populations.

METHODS

Searches of PubMed and FDA surveillance studies were undertaken to complete an exhaustive review. Search terms included 'DAAs', 'safety', and 'tolerability'.

RESULTS

While DAAs are remarkably well tolerated, they are accompanied by unique AEs. Simeprevir, an NS3/4A protease inhibitor, has been known, albeit infrequently, to cause mild hyperbilirubinemia and photosensitivity reactions; and paritaprevir boosted with ritonavir causes bilirubin and ALT elevations. Asunaprevir, another protease inhibitor, infrequently causes elevated transaminase levels. NS5A and NS5B inhibitors are well tolerated, although sofosbuvir is contraindicated in patients with severe renal impairment. Ribavirin co-administered in certain treatment regimens has been associated with cough, rash and haemolytic anaemia.

CONCLUSIONS

With the impending reality of a more tolerable interferon-sparing regimen, the future of DAA therapy offers shorter treatment duration, simplified disease management, and a patient-centred regimen. With advantages come drawbacks, including development of resistance to therapy and accessibility to this expensive treatment. DAA therapy continues to advance at a brisk pace with a promising trend for higher tolerability, even in difficult-to-treat subgroups such as those with cirrhosis, nonresponders to prior therapy, and transplant recipients. Subgroup-specific contraindications and safety-related limitations are active areas of research. Concerted research efforts and continuing advances lend hope to the goal of rendering HCV a routinely curable disease.

Pharmacokinetic, Pharmacodynamic, and Drug-Interaction Profile of the Hepatitis C Virus NS5B Polymerase Inhibitor Sofosbuvir

Sofosbuvir (SOVALDI(®)), a potent, once-daily, orally administered nucleotide analog prodrug inhibitor of the hepatitis C virus (HCV) NS5B polymerase is approved in the USA, EU, Canada, and other regions for the treatment of HCV infection as a component of an antiviral treatment regimen. Sofosbuvir undergoes intracellular activation to form GS-461203 (active triphosphate, not detected in plasma), and ultimately the inactive, renally eliminated metabolite GS-331007. GS-331007 was identified as the primary analyte of interest for clinical pharmacology studies as it accounted for >90 % of systemic drug-related material exposure, and provided comparable exposure-response relationships for viral kinetics as observed for sofosbuvir. GS-331007 and sofosbuvir exhibit linear pharmacokinetics with minimal accumulation upon multiple dosing. Compared to healthy subjects, HCV-infected patients had modestly lower (39 %) GS-331007 area under the plasma concentration-time curve (AUC) and higher sofosbuvir AUC (60 %). Sofosbuvir can be administered without dose modification in HCV-infected patients with any degree of hepatic impairment or mild to moderate renal impairment. Sofosbuvir has a low propensity for clinically significant drug interactions with common concomitant medications used by HCV-infected patients. Clinically significant alterations in GS-331007 or sofosbuvir exposures are limited to potent inducers of intestinal P-glycoprotein that may lower exposure. In HCV-infected patients, demographic variables do not significantly influence GS-331007 and sofosbuvir exposures and no consistent exposure-response relationships were observed for efficacy or safety. This review focuses on the clinical pharmacokinetics, pharmacodynamics, and pharmacokinetic-pharmacodynamic relationships of sofosbuvir, and summarizes a number of drug interaction studies with important concomitant medications commonly used by HCV-infected patients.

Tackling HCV-3 in Asia: Breakthroughs for Efficient and Cost-effective Treatment Strategies

Hepatitis C virus (HCV) is known to cause chronic hepatitis C, and its sequelae of cirrhosis and hepatocellular carcinoma. Hepatitis C genotype 3 (HCV-3) in particular is notorious for causing accelerated liver fibrosis, cardiovascular, and metabolic effects, thus increasing morbidity and mortality. It is the commonest variant in Asian countries like India and Pakistan. It is also one of the hardest-to-treat genotypes, especially among treatment-experienced and cirrhotic patients. Due to limited health care affordability and accessibility in these areas, many patients remain untreated. Until recently, the established therapy for HCV had been a combination of pegylated interferon + ribavirin. However, it was only effective in about half of patients and had severe adverse effects; hence a more efficacious option needed to be found. Recent advances have led to the development of sofosbuvir, an NS5B inhibitor that is fast becoming the standard of care, in combination with other novel drugs. It was initially marketed at $1,000 per pill, a cost that was too high for most. Thus, it has not been utilized as a global therapy as yet. Formulation of effective interferon-free regimens is a huge milestone, and awareness needs to be raised regarding these new highly effective options in both the physician and the patient population. This article discusses the newest drugs and combinations that have been developed in the fight against HCV-3, as a treatment outline for HCV-3-dominant areas. It also highlights recent breakthroughs in cost reductions of these drugs and the effort to make them globally accessible.

HOW TO CITE THIS ARTICLE

Saeed N, Gurakar A. Tackling HCV-3 in Asia: Breakthroughs for Efficient and Cost-effective Treatment Strategies. Euroasian J Hepato-Gastroenterol 2016;6(1):35-42.

Interferon-free regimens for the treatment of hepatitis C virus in liver transplant candidates or recipients

The goal of therapy in chronic hepatitis C virus (HCV) infection is sustained virological response (SVR) which reflects HCV eradication. Treatment against HCV has dramatically improved with the recent availability of direct-acting antivirals (DAAs) including sofosbuvir, simeprevir, daclatasvir, ledipasvir/sofosbuvir, paritaprevir/ombitasvir and dasabuvir. Carefully selected combinations of these DAAs offer the potential for highly effective all-oral safe regimens even for patients with decompensated cirrhosis or liver transplant (LT) recipients. Like all current protease inhibitors, simeprevir and paritaprevir should not be used in patients with Child C cirrhosis, while sofosbuvir and ledipasvir/sofosbuvir should not be given in patients with severe renal impairment and glomerular filtration rate less than 30 mL/min. Drug-drug interactions may still occur with the current DAAs particularly in post-LT patients, in whom simeprevir should not be co-administered with cyclosporine and dose adjustments of calcineurin inhibitors are required in case of regimens including the ritonavir boosted paritaprevir. Phase II clinical trials and real life cohort studies have shown that sofosbuvir based combinations are safe and can achieve improvements of clinical status, high SVR rates and even prevention of post-LT HCV recurrence in patients with decompensated cirrhosis or LT-candidates. In the post-LT setting, sofosbuvir based regimens and the combination of paritaprevir/ombitasvir and dasabuvir have been reported to be safe and achieve high SVR rates, similar to those in non-transplant patients, being effective even in cases with cholestatic fibrosing hepatitis. Ongoing clinical trials and rapidly emerging real life data will further clarify the safety and efficacy of the new regimens in these settings.

New therapies for hepatitis C: considerations in patients with renal impairment

Hepatitis C virus (HCV) is a major public health issue because infection may lead to liver failure, cirrhosis and hepatocellular carcinoma. In patients with renal dysfunction, hepatitis C can also worsen the underlying renal disease. Treating HCV infection is thus mandatory in this population. New therapies for hepatitis C have recently been developed, and some have been launched. Most of them are used in combination with the current standard of care, ribavirin and pegylated interferon alfa. Some of them can be used in regimens without ribavirin and/or pegylated interferon. However, few data are available on dosage adjustment for renal function in patients receiving these very new drugs. We reviewed the literature on this subject and gathered information, although scarce, to propose guidelines for using these drugs in patients with chronic kidney disease.

HIV and HCV Medications in End-Stage Renal Disease

Human immunodeficiency virus (HIV) infection and hepatitis C virus (HCV) infection affect populations worldwide. With the availability of over 35 Food and Drug Administration approved medications for treatment of HIV, the morbidity and mortality associated with HIV has greatly improved. On the other hand, treatment options for HCV have been limited until very recently. While the use of protease inhibitors (such as boceprevir and telaprevir) has become standard of care for treatment of hepatitis C in the general population, data for individuals with impaired kidney function, particularly those on dialysis, are extremely limited. Use of medications in dialysis patients can be challenging given the dose adjustments that must be made for renally cleared molecules, and potentially increased impact of adverse effects such as anemia. Recommendations for dosing of marketed therapies for HIV and HCV are reviewed.

Sofosbuvir and ribavirin before liver re-transplantation for graft failure due to recurrent hepatitis C: a case report

Background

Recurrent hepatitis C virus infection after liver transplantation is associated with reduced graft and patient survival. Re-transplantation for graft failure due to recurrent hepatitis C is controversial and not performed in all centers.

Case presentation

We describe a 54-year-old patient with hepatitis C virus genotype 1b infection and a null response to pegylated interferon-α and ribavirin who developed decompensated graft cirrhosis 6 years after a first liver transplantation. Treatment with sofosbuvir and ribavirin allowed for rapid negativation of serum HCV RNA and was well tolerated despite advanced liver and moderate renal dysfunction. Therapeutic drug monitoring did not reveal any clinically significant drug-drug interactions. Despite virological response, the patient remained severely decompensated and re-transplantation was performed after 46 days of undetectable serum HCV RNA. The patient is doing well 12 months after his second liver transplantation and remains free of hepatitis C virus.

Conclusions

The use of directly acting antivirals may allow for successful liver re-transplantation for recipients who remain decompensated despite virological response and is likely to improve the outcome of liver re-transplantation for end-stage recurrent hepatitis C.

Management of patients with hepatitis C infection and renal disease

Hepatitis C virus (HCV) infection in patients with end-stage renal disease (ESRD) is associated with more rapid liver disease progression and reduced renal graft and patients' survival following kidney transplantation. Evaluations and management of HCV in patients with renal disease are challenging. The pharmacokinetics of interferons (IFN), ribavirin (RBV) and some direct acting antiviral (DAA), such as sofosbuvir, are altered in patients with ESRD. With dose adjustment and careful monitoring, treatment of HCV in patients with ESRD can be associated with sustained virological response (SVR) rates nearly comparable to that of patients with normal renal function. DAA-based regimens, especially the IFN-free and RBV-free regimens, are theoretically preferred for patients with ESRD and KT in order to increase SVR rates and to reduce treatment side effects. However, based on the data for pharmacokinetics, dosing safety and efficacy of DAA for patients with severe renal impairment are lacking. This review will be focused on the evaluations, available pharmacologic data, and management of HCV in patients with severe renal impairment, patients who underwent KT, and those who suffered from HCV-related renal disease, according to the available treatment options, including DAA.

Peginterferon alfa-2a with or without low-dose ribavirin for treatment-naive patients with hepatitis C virus genotype 2 receiving haemodialysis: a randomised trial

OBJECTIVE

Data comparing the efficacy and safety of combination therapy with peginterferon plus low-dose ribavirin and peginterferon monotherapy in treatment-naive haemodialysis patients with hepatitis C virus genotype 2 (HCV-2) infection are limited.

DESIGN

In this randomised trial, 172 patients received 24 weeks of peginterferon alfa-2a 135 μg/week plus ribavirin 200 mg/day (n=86) or peginterferon alfa-2a 135 μg/week (n=86). The efficacy and safety endpoints were sustained virological response (SVR) rate and adverse event (AE)-related withdrawal rate.

RESULTS

Compared with monotherapy, combination therapy had a greater SVR rate (74% vs 44%, relative risk (RR): 1.68 [95% CI 1.29 to 2.20]; p<0.001). The beneficial effect of combination therapy was more pronounced in patients with baseline viral load ≥800,000 IU/mL than those with baseline viral load <800,000 IU/mL (RR: 3.08 [95% CI 1.80 to 5.29] vs. RR: 1.11 [95% CI 0.83 to 1.45]; interaction p=0.001). Patients receiving combination therapy were more likely to have a haemoglobin level of <8.5 g/dL (70% vs. 8%, risk difference (RD): 62% [95% CI 50% to 73%]; p<0.001) and required a higher dosage [mean: 13,417 vs. 6667 IU/week, p=0.027] of epoetin β to manage anaemia than those receiving monotherapy. The AE-related withdrawal rates were 6% and 3% in combination therapy and monotherapy groups, respectively (RD: 2% [95% CI -4% to 9%]).

CONCLUSIONS

In treatment-naive haemodialysis patients with HCV-2 infection, combination therapy with peginterferon plus low-dose ribavirin achieved a greater SVR rate than peginterferon monotherapy. Most haemodialysis patients can tolerate combination therapy.

TRIAL REGISTRATION NUMBER

ClinicalTrial.gov number, NCT00491244.

Sofosbuvir and simeprevir combination therapy in the setting of liver transplantation and hemodialysis

We report safety, tolerability, and 12-week sustained virologic response with half-standard dose sofosbuvir and standard-dose simeprevir combination therapy in a hepatitis C virus genotype 1a-infected liver transplant recipient on hemodialysis - uncharted territory for sofosbuvir-based therapy. The patient was a non-responder to prior treatment with pegylated interferon plus ribavirin. Sofosbuvir efficacy was maintained despite pill-splitting and administration of half-standard dose, 200 mg per day. No drug-drug interactions were noted with tacrolimus-based immunosuppression. Laboratory tests remained stable or improved during therapy. Our observation, if reproduced in a larger study, may lead to significant improvement in clinical outcomes and cost savings in this patient population.

Sofosbuvir for treatment of chronic hepatitis C

Chronic hepatitis C is a leading cause of liver-related morbidity and mortality worldwide. If untreated, chronic hepatitis C can progress to advanced liver fibrosis, cirrhosis, liver failure, hepatocellular carcinoma and death. Until recently, treatment of hepatitis C predominantly constituted an immunomodulatory agent, peg-interferon-alfa and ribavirin. In 2011, the first class of directly acting antiviral agents, HCV NS3/4A serine protease inhibitors, was added to peg-interferon-alfa and ribavirin with increased efficacy. In the past year, an NS5B inhibitor, sofosbuvir, has emerged as a potent agent with pangenotypic efficacy, resulting in the first interferon-free regimen for the treatment of hepatitis C. This review summarizes the data that resulted in regulatory approval of sofosbuvir and highlights the future of hepatitis C therapy with sofosbuvir as the backbone of a highly effective antiviral regimen.

Efficacy of new direct acting antivirals in transplant recipients and patients with advanced disease

The development of new direct acting antivirals constitutes a clinical revolution in the field of hepatitis C therapy and, most probably, in the history of Hepatology. Difficult-to-treat patients, such as cirrhotics or patients in the peri-transplant setting, will clearly benefit from these therapies, particularly from interferon-free all-oral combinations. However, despite the substantial improvement of the hepatitis C drug market, access to these therapies will likely be different around the world due to economic restrictions. This review aims to clarify the current stage of different antiviral strategies (with or without interferon) in these difficult populations by analysing specific efficacy and safety results in patients with cirrhosis, patients on the waiting list for liver transplantation and recipients with hepatitis C recurrence after liver transplantation. Hitherto, some important challenges still remain unanswered in these patients and will need to be assessed in clinical practice, such as the evaluation of safety and efficacy in advanced cirrhotic patients with portal hypertension, the impact (if any) of viral clearance on clinical outcomes in patients with decompensated liver disease, the role of ribavirin in all-oral combinations, the relevance of the development of multi-drug viral resistant strains and the drug-drug interaction profiles of these drugs, especially after liver transplantation.

Treatment options in patients with decompensated cirrhosis, pre- and post-transplantation

Interferon-based treatments have a poor safety profile and limited efficacy in patients with advanced liver disease and in patients with hepatitis C (HCV) recurrence after liver transplantation (LT). Despite the recent approval of the first interferon-free regimen, which will be followed by several other interferon-free combinations in 2014 and 2015, data in patients with advanced cirrhosis and hepatitis C after LT are still limited. One study has already proven the concept that graft HCV infection can be prevented in a significant proportion of patients by treating them with sofosbuvir and ribavirin while awaiting LT. Two interferon-free regimens have also demonstrated a high efficacy in patients with hepatitis C recurrence after transplantation. Before these treatment strategies can be implemented in clinical practice, a few issues need to be addressed: (1) safety and efficacy of new antivirals in patients with decompensated cirrhosis, (2) the impact of viral clearance on liver function, (3) the potential consequences of virological failure (and the selection of multi-drug resistant HCV strains) in patients with decompensated cirrhosis or with severe hepatitis C recurrence after LT, and (4) drug-drug interactions (DDI) profiles. Finally, in the transplant setting it is also relevant to learn which strategy is most cost-effective in minimizing the negative impact of hepatitis C: preventing graft infection by treating patients before transplantation or treating hepatitis C recurrence after LT.

Hepatitis C virus infection and kidney transplantation in 2014: what's new?

Chronic hepatitis C virus (HCV) infection remains an important health problem, which is associated with deleterious consequences in kidney transplant recipients. Besides hepatic complications, several extrahepatic complications contribute to reduced patient and allograft survival in HCV-infected kidney recipients. However, HCV infection should not be considered as a contraindication for kidney transplantation because patient survival is better with transplantation than on dialysis. Treatment of HCV infection is currently interferon-alpha (IFN-α) based, which has been associated with higher renal allograft rejection rates. Therefore, antiviral treatment before transplantation is preferable. As in the nontransplant setting, IFN-free treatment regimens, because of their greater efficacy and reduced toxicity, currently represent promising and attractive therapeutic options after kidney transplantation as well. However, clinical trials will be required to closely evaluate these regimens in kidney recipients. There is also a need for prospective controlled studies to determine the optimal immunosuppressive regimens after transplantation in HCV-infected recipients. Combined kidney and liver transplantation is required in patients with advanced liver cirrhosis. However, in patients with cleared HCV infection and early cirrhosis without portal hypertension, kidney transplantation alone may be considered. There is some agreement about the use of HCV-positive donors in HCV-infected recipients, although data regarding posttransplant survival rates are controversial.

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..

Sofosbuvir, a NS5B polymerase inhibitor in the treatment of hepatitis C: a review of its clinical potential

Treatment of chronic hepatitis C (HCV) is currently undergoing a significant change. Traditional interferon-based therapy has been limited by both efficacy and tolerability, and many direct acting antiviral (DAA) drugs are emerging. Sofosbuvir (GS-7977) is a HCV NS5B nucleotide polymerase inhibitor that has now been evaluated extensively in phase II and III interferon-free clinical trials. The focus of this review is on the clinical potential of sofosbuvir in the treatment of HCV. Sofosbuvir has a pan-genotypic effect on HCV, although viral genotype-specific differences in sustained virological response (SVR) have emerged in phase III clinical trials. Sofosbuvir has been studied both as dual therapy with ribavirin and also as triple therapy with either NS5A inhibitors or a protease inhibitor. High rates of SVR have been reported with these interferon-free combinations, particularly with genotypes 1 and 2, and the safety profile has been very favourable in both cirrhotic and noncirrhotic patients, without issues of viral resistance. Interferon-free, once-daily treatment of HCV is now becoming a reality.

Drug-drug interactions during antiviral therapy for chronic hepatitis C

The emergence of direct-acting antiviral agents (DAAs) for HCV infection represents a major advance in treatment. The NS3 protease inhibitors, boceprevir and telaprevir, were the first DAAs to receive regulatory approval. When combined with PEG-IFN and ribavirin, these agents increase rates of sustained virologic response in HCV genotype 1 to ∼70%. However, this treatment regimen is associated with several toxicities. In addition, both boceprevir and telaprevir are substrates for and inhibitors of the drug transporter P-glycoprotein and the cytochrome P450 enzyme 3A4 and are, therefore, prone to clinically relevant drug interactions. Several new DAAs for HCV are in late stages of clinical development and are likely to be approved in the near future. These include the protease inhibitors, simeprevir and faldaprevir, the NS5A inhibitor, daclatasvir, and the nucleotide polymerase inhibitor, sofosbuvir. Herein, we review the clinical pharmacology and drug interactions of boceprevir, telaprevir and these investigational DAAs. Although boceprevir and telaprevir are involved in many interactions, these interactions are manageable if health-care providers proactively identify and adjust treatments. Emerging DAAs seem to have a reduced potential for drug interactions, which will facilitate their use in the treatment of HCV.

Sofosbuvir and daclatasvir combination therapy in a liver transplant recipient with severe recurrent cholestatic hepatitis C

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

Pharmacokinetics of new oral hepatitis C antiviral drugs

INTRODUCTION

Approximately 175 million people worldwide are chronically infected with the hepatitis C virus (HCV), representing 3% of the total world population. Until recently, the only available therapeutic option for these patients was the combination of pegylated IFN-α plus ribavirin that overall resulted in HCV eradication in less than a half of cases. The development of new therapies with greater efficacy has been eagerly awaited but new challenges have emerged, with drug interactions being among the most challenging.

AREAS COVERED

This review updates the main pharmacokinetic and pharmacodynamic characteristics of the most promising new oral direct-acting antivirals (DAA) for hepatitis C. Given that a large proportion of chronic hepatitis C patients receive other medications, drug interactions are further discussed.

EXPERT OPINION

The recent approval of the first HCV genotype 1 protease inhibitors is a landmark step in the fight against the HCV pandemic. The benefit of higher rates of response along with shorter duration of treatment is counterbalanced by significant drug interactions and unprecedented complexities in the use of these drugs and management of their side effects. The knowledge of key pharmacologic parameters of distinct DAA is important for care providers in charge of chronic hepatitis C patients as it will avoid the danger of unexpected drug interactions. This concern must be particularly emphasized in special group populations, such as in HIV-HCV coinfected individuals and transplant patients, in whom interactions between DAA and antiretrovirals or immunosuppressants, respectively, are frequent.