Directly acting antivirals for hepatitis C and antiretrovirals: potential for drug-drug interactions. Curr Opin HIV AIDS. 2011;6:514-526. [PMID: 22001895 DOI: 10.1097/coh.0b013e32834b54dc]

Impact of HIV and chronic kidney disease comorbidities on hepatitis C treatment choices, drug-drug interactions and hepatitis C cure

Background Human immunodeficiency virus (HIV) co-infection and chronic kidney disease add challenges to hepatitis C virus treatment. Objective To conduct a comparative study of treatment choices, drug–drug interactions and clinical outcomes in hepatitis C mono-infected patients, or those with HIV or chronic kidney disease comorbidities. Setting Hepatitis C treatment centers of West Midlands England, United Kingdom. Method An observational study was conducted analyzing datasets of all hepatitis C patients that were referred to a large tertiary liver unit in the West Midlands, UK between July 2015 and January 2018. Patients aged ≥ 18 years with diagnosis of hepatitis C alone or co-infected with HIV or comorbid with chronic kidney disease were eligible. Main outcome measures The treatment choices, relevant potential drug–drug interactions and sustained virologic response 12 weeks post end of treatment were assessed. Results Out of 313 patients, 154 (49.2%) were hepatitis C mono-infected, 124 (39.6%) hepatitis C/HIV co-infected and 35 (11.2%) were hepatitis C/chronic kidney disease comorbid. There were 151 (98.1%) of hepatitis C mono-infected, 110 (88.7%) of hepatitis C/HIV and 20 (57.1%) of hepatitis C/chronic kidney disease patients treated with 1st line regimens. Significantly more patients who had co-morbidity with either HIV or chronic kidney disease were prescribed 2nd line regimens (8.1% and 37.1% respectively), compared to patients with hepatitis C mono-infection (1.9%) (P value < 0.05). Comorbid patients (12.1% of HIV and 25.8% of chronic kidney disease) were more likely to required drug–drug interactions advice (grade 5) than hepatitis C mono-infected (1.8%). Higher cure rates were observed in hepatitis C mono-infected (95.33%), hepatitis C/HIV (96.1%) compared to hepatitis C/chronic kidney disease patients (90.3%). Conclusion This study shows that treatment pathways permitting access to individual treatment adjustments in accordance with comorbidities and with consideration of drug–drug interaction in a multi-disciplinary team, provides successful outcomes in hepatitis C patients co-morbid with HIV or chronic kidney disease.

Multiplexed therapeutic drug monitoring (TDM) of antiviral drugs by LC-MS/MS

Background

Therapeutic drug monitoring (TDM) can be a useful tool in the clinical management of anti-hepatitis C virus (anti-HCV) drugs. Methods for the determination of various types of anti-HCV drugs in biological samples are, therefore, needed for clinical laboratories.

Objective

In this work, employing the LC-MS/MS approach, we aimed to develop a multiplexed method for identification of the following anti-HCV drugs: Ribavirin (RBV), Boceprevir (BOC), Telaprevir (TVR), Simeprevir (SIM), Daclatasvir (DAC), Sofosbuvir (SOF) and its metabolite GS 331007 (SOFM) in liquid plasma and in dried plasma spots (DPSs).

Method

A single-step extractive-deproteinization was employed for both liquid plasma and DPSs. Reverse-phase liquid chromatography coupled with MRM detection was developed for multiplexed drug detection and quantification.

Results

Sensitivities (expressed as LOQ) were 10 (±1.2), 10 (±4.9), 10 (±4.4), 10 (±4.4), 10 (±6.4), 10 (±3.4), 10 (±6.4) ng/ml for RBV, SOFM, SOF, DAC, BOC, TVR, and SIM, respectively; accuracy (expressed as BIAS%) was <10% for all drugs; reproducibility (intra- and inter-day CV%) was <10% for all drugs; dynamic range was 10-10,000 ng/ml for all drugs.

Conclusions

A novel, simple, rapid and robust LC-MS/MS multiplex assay for the TDM of various anti-HCV drugs that are currently in the clinic was successfully developed. Application to DPS samples enabled TDM to be used for outpatients as well.

Efficacy and safety of sofosbuvir/ledipasvir for the treatment of patients with hepatitis C virus re-infection after liver transplantation

BACKGROUND

Hepatitis C virus (HCV) infection is associated with a particularly poor outcome after liver transplantation. In December 2014, sofosbuvir/ledipasvir (SOF/LDV) fixed-dose combination (FDC) was approved for HCV genotype 1 and 4 in Europe. In orthotopic liver transplantation (OLT) recipients, the interferon-free treatment of HCV re-infection with novel direct-acting antivirals has been demonstrated to be safe and effective in clinical trials, but real-world data are missing. The aim of this study was to investigate the safety and efficacy of SOF/LDV FDC in OLT recipients in the real-life setting.

METHODS

All consecutive OLT patients started on SOF/LDV FDC for 12 or 24 weeks at the University Medical Center Hamburg-Eppendorf and Medical School Hannover between October 2014 and August 2015 were retrospectively analyzed (n = 30). The primary efficacy endpoint was sustained virological response (SVR), i.e., absence of viremia 12 weeks after end of treatment (SVR 12). Liver function tests, creatinine, blood count, and HCV RNA (by polymerase chain reaction assay) were determined at each visit.

RESULTS

SVR was achieved in 29/30 patients (96.67%) treated with SOF/LDV ± ribavirin (RBV) for 12 (n = 4) or 24 weeks (n = 25). Twenty-five patients (86.2%) received RBV. However, in 15 of the 25 patients, RBV administration had to be discontinued because of severe anemia (57.7%). One RBV-treated patient died of a myocardial infarction during antiviral therapy; this event was most likely not directly related to SOF/LDV. Aside from RBV-associated anemia, no severe side effects of the antiviral regimen were observed.

CONCLUSION

Antiviral treatment with SOF/LDV is highly effective, safe, and well tolerated in OLT recipients. The addition of RBV often results in severe anemia, requiring dose reduction or discontinuation.

Anti-HCV therapy: Whether it comes into the age of DAA-based specific therapy?

Hepatitis C virus (HCV) infection is one of the main causes of chronic liver diseases. Direct-acting antiviral (DAA) agents undoubtedly bring hope for patients who cannot tolerate or are not suitable for interferon therapy. There have been six foreign guidelines for anti-HCV therapy in 2014, and in October this year, China also updated its guideline for the diagnosis and treatment of HCV infection. In this paper I review the current status and future perspectives of HCV treatment.

Dual antiviral therapy for HIV and hepatitis C - drug interactions and side effects

INTRODUCTION

Roughly 20% of HIV-positive persons worldwide are coinfected with hepatitis C virus (HCV). The recent advent of direct-acting antivirals (DAA) that cure most hepatitis C patients has attracted much attention. Knowledge on drug interactions between DAA and antiretrovirals (ARV) may allow maximizing antiviral efficacy while minimizing drug-related toxicities.

AREAS COVERED

We review the most frequent side effects and clinically significant drug interactions between DAA and ARV. We further discuss how they can be prevented and managed in HIV/HCV-coinfected patients.

EXPERT OPINION

The safety profile of current DAA and the most recently approved ARV is quite favorable. Interactions between DAA and ARV could be frequent in clinical practice. The most common drug interactions affect drug metabolism by inducing or inhibiting the cytochrome P450 system, leading to abnormal drug exposures. Throughout this mechanism HCV and HIV protease inhibitors interact, especially when co-formulated with ritonavir as a pharmacoenhancer, and non-nucleoside HCV and HIV polymerase inhibitors. In contrast, HIV and HCV nucleos(t)ide polymerase inhibitors, and most HCV NS5A inhibitors (i.e., ledipasvir) and HIV integrase inhibitors (i.e., dolutegravir), do not or only marginally affect CYP450, and therefore are free of significant drug interactions. Exposure to HIV and HCV nucleos(t)ide analogues (i.e., tenofovir and sofosbuvir, respectively) is subject to induction/inhibition of drug transporters (i.e., P-glycoprotein).

Lipid dysregulation in hepatitis C virus, and impact of statin therapy upon clinical outcomes

The hepatitis C virus (HCV) is one of the most common causes of chronic liver disease and the leading indication for liver transplantation worldwide. Every aspect of the HCV life cycle is closely tied to human lipid metabolism. The virus circulates as a lipid-rich particle, utilizing lipoprotein cell receptors to gain entry into the hepatocyte. It has also been shown to upregulate lipid biosynthesis and impair lipid degradation, resulting in significant intracellular lipid accumulation and circulating hypocholesterolemia. Patients with chronic hepatitis C (CHC) are at increased risk of hepatic steatosis, fibrosis, and cardiovascular disease including accelerated atherosclerosis. HMG CoA Reductase inhibitors, or statins, have been shown to play an important role in the modulation of hepatic steatosis and fibrosis, and recent attention has focused upon their potential therapeutic role in CHC. This article reviews the hepatitis C viral life cycle as it impacts host lipoproteins and lipid metabolism. It then describes the pathogenesis of HCV-related hepatic steatosis, hypocholesterolemia and atherosclerosis, and finally describes the promising anti-viral and anti-fibrotic effects of statins, for the treatment of CHC.

Drug interactions with new hepatitis C oral drugs

INTRODUCTION

Chronic hepatitis C virus (HCV) infection has recently become a curable disease with antiviral therapy. The knowledge of drug interactions using direct-acting antivirals (DAA) may permit maximizing antiviral efficacy and avoiding drug-related toxicities. Ageing in the chronic hepatitis C population, along with added co-morbidities that require other medications, has increased the attention on drug interactions using DAA.

AREAS COVERED

This review provides an update of the most clinically significant pharmacokinetic and pharmacodynamic drug interactions occurring between currently available DAA and other medications. The review also revisits how drug interactions with DAA can be prevented and managed.

EXPERT OPINION

Interactions between DAA and other drugs are frequent in clinical practice. The most frequent drug interactions modify drug metabolism by inducing or inhibiting the cytochrome P450, leading to abnormal drug exposures. Through this mechanism HCV protease inhibitors, especially when co-formulated with ritonavir as pharmacoenhancer, and non-nucleoside HCV polymerase inhibitors interact with other medications. In contrast, NS5B nucleos(t)ide analog inhibitors (i.e., sofosbuvir) and some HCV NS5A inhibitors (i.e., ledipasvir), which do not or only marginally affect CYP450, are relatively free of significant pharmacokinetic interactions. However, exposure to HCV nucleos(t)ide analogs may be influenced by induction/inhibition of drug transporters (i.e., P-glycoprotein) as well as by pharmacodynamic interference with other nucleos(t)ide analogs used as antivirals or cancer drugs. Drug interactions for some NS5A inhibitors (i.e., daclatasvir) are generally moderate and can be managed with dose adjustments.

[Drug-drug interaction with telaprevir or boceprevir in liver transplant patients: about four cases]

Boceprevir and telaprevir are both direct-acting antivirals indicated, as part of combination therapy for the management of chronic hepatitis C virus (HCV) genotype 1 infection. Transplanted patients treated with anticalcineurines (tacrolimus and cyclosporine) are confronted with major risks of interactions. Indeed, these antiviral are strong inhibitors of the enzyme cytochrome 3A4/A5, responsible for the metabolisme of ciclosprine and tacrolimus. The literature gives evidence of the dangerousness of this drug-drug interaction. We report four clinical cases illustrating the dosage adaptations at liver transplant patients and treated by telaprevir or boceprevir. To protect the immunosuppressive efficiency, a multidisciplinary care and narrow monitoring of the interaction between immunosuppressing agents and protease inhibitors were necessary.

Liver fibrosis, host genetic and hepatitis C virus related parameters as predictive factors of response to therapy against hepatitis C virus in HIV/HCV coinfected patients

OBJECTIVE

To establish the role of liver fibrosis as a predictive tool of response to pegylated interferon alpha (Peg-IFN) and ribavirin (RBV) treatment in human immunodeficiency (HIV)/hepatitis C virus (HCV) coinfected patients, in addition to recognized predictive factors (HCV load, HCV genotype, IL-28B polymorphism).

PATIENTS AND METHODS

A sample of 267 HIV/HCV coinfected patients was treated with Peg-IFN and RBV. Predictive factors of rapid (RVR) and sustained (SVR) virological response were analyzed. Independent variables were age, sex, IL28B, -238 TNF-α and -592 IL-10 polymorphisms, HCV genotype, HCV-RNA levels, significant fibrosis or cirrhosis and CD4+ T cell count.

RESULTS

Patients infected by HCV genotype 1 (n = 187) showed RVR and SVR in 12% and 39% of cases, respectively. The parameters associated with RVR were IL28B genotype CC and plasma HCV-RNA levels <600,000 IU/ml. Advanced liver fibrosis was negatively associated with SVR in patients without RVR. A SVR was obtained in 42% of subjects with HCV genotype 4, and the independent factors associated with SVR were IL28B genotype CC and an HCV-RNA <600,000 IU/ml. A SVR was obtained in 66% of patients with HCV genotypes 2/3; in this case, the independent parameter associated with SVR was the absence of significant liver fibrosis. TNF-α and IL-10 polymorphisms were not associated with SVR, although a significantly higher percentage of -238 TNF-α genotype GG was detected in patients with significant liver fibrosis.

CONCLUSIONS

In HIV/HCV coinfected patients with HCV genotypes 1 or 4, RVR, mainly influenced by genotype IL28B and HCV-RNA levels, reliably predicted SVR after 4 weeks of therapy with Peg-IFN plus RBV. In patients infected by HCV genotype 3, an elevated relapse rate compromised the influence of RVR on SVR. Relapses were related to the presence of advanced liver fibrosis. Liver cirrhosis was associated with a -238 TNF-α polymorphism in these patients.

Drug interactions and protease inhibitors used in the treatment of hepatitis C: how to manage?

PURPOSE

The first-generation protease inhibitors (PI) boceprevir and telaprevir combined with pegylated interferon have revolutionized the treatment of type-1 hepatitis C by increasing the rates of sustained virologic response. However, they induce drug interactions, and their clinical relevance is difficult to predict. This review compiles available data on drug-drug interactions (DDI) based on their pharmacokinetic and pharmacodynamic properties with the aim of assisting clinicians in managing DDI METHODS: PubMed, drug interaction databases and hepatology and infectious disease conference abstracts were systematically searched using the key search terms "interaction", "hepatitis C", "telaprevir" and "boceprevir". All known interactions were compiled and reclassified according to their pharmacokinetic and pharmacodynamic mechanisms. The state of knowledge of interaction mechanisms are reported and a therapeutic approach is proposed.

RESULTS

Boceprevir and telaprevir are both substrates and potent inhibitors of cytochrome P450 3A4 and the drug transporter P-glycoprotein. They induce overdosage but can sometimes decrease the effect of other drugs by inducing other cytochromes. Overdosage or low dosage mainly affects drugs with a narrow therapeutic range, such as immunosuppressants or antiretrovirals. The distribution and elimination of PI are unaffected by interactions. In terms of pharmacodynamic interactions, PI can trigger drug-induced QT interval prolongation, which means that clinicians should manage such risk factors as potassium/magnesium levels or avoid other QT-prolonging drugs.

CONCLUSIONS

Management of hepatitis C therapy is complex. The key to interpreting DDI data is a solid understanding of the pharmacokinetic and pharmacodynamic profiles of the drugs involved. Their ability to inhibit cytochrome P450 3A4 and prolong the QT interval can have significant clinical consequences. This review provides a practical guide to the safe and effective management of therapy with boceprevir and telaprevir.

Safety and efficacy of faldaprevir with pegylated interferon alfa-2a and ribavirin in Japanese patients with chronic genotype-1 hepatitis C infection

BACKGROUND & AIMS

Faldaprevir (BI 201335) is a potent once-daily (QD) NS3/4A protease inhibitor for the treatment of patients with genotype-1 (GT-1) hepatitis C virus (HCV). The aim of this study was to evaluate the safety, pharmacokinetics and efficacy of faldaprevir plus pegylated interferon alfa-2a (PegIFN) and ribavirin (RBV) in Japanese patients infected with chronic GT-1 HCV.

METHODS

Part 1 of this phase II study was a randomized, double-blind, placebo-controlled, dose-ascending study. Treatment-naïve patients received faldaprevir 120 or 240 mg QD, or placebo, plus PegIFN/RBV for 4 weeks, then PegIFN/RBV alone for 44 weeks. In Part 2 (open label), treatment-experienced patients received faldaprevir 240 mg QD plus PegIFN/RBV for 4 weeks, then PegIFN/RBV alone for 44 weeks. Efficacy was assessed using sustained virological response (SVR) 24 weeks after treatment completion. The pharmacokinetics, safety and tolerability of faldaprevir were also assessed.

RESULTS

SVR was achieved by 4/6 (67%) treatment-naïve patients treated with faldaprevir 120 mg QD, 5/6 (83%) patients treated with faldaprevir 240 mg QD and 2/4 (50%) patients who received placebo. Of the treatment-experienced patients, 3/6 (50%) achieved SVR. Faldaprevir was well tolerated. There was one serious adverse event, which was not considered to be treatment related. Rash and hyperbilirubinaemia were more frequently reported with faldaprevir than with placebo in treatment-naïve patients, but no cases were severe or serious and none led to discontinuation. Steady-state plasma concentrations of faldaprevir were reached within 7 days of QD dosing.

CONCLUSIONS

Faldaprevir with PegIFN/RBV was efficacious and well tolerated, supporting further evaluation of this combination in Japanese patients.

Hepatitis C and lipid metabolism, hepatic steatosis, and NAFLD: still important in the era of direct acting antiviral therapy?

Chronic hepatitis C (CHC) and nonalcoholic fatty liver disease (NAFLD) have an individual prevalence of 1.8-3% and at least 30%, respectively, in the United States. It is therefore not surprising that there is overlap between these two common chronic liver diseases, although the relationship appears to go beyond isolated co-existence. Hepatic steatosis is a common feature of CHC infection and can be related to both metabolic and viral specific factors. Steatosis in the setting of nongenotype 3 CHC has been predictive of response to therapy prior to the advent of the direct acting antiviral medications (DAAs). Similarly, lipid metabolism appears important in response to CHC treatment. The pathways for both lipid homeostasis and NAFLD as it pertains to CHC infection as well as the utilization of statin therapy in CHC infection will be reviewed with a focus on the relevance of these topics in the era of DAA therapy.

Sustained virological response in HIV/HCV co-infected patients treated with pegylated interferon/ribavirin can be predicted from the overall rate of viral load decline over the first 4 weeks of therapy

OBJECTIVE

It is not known whether the probability of achieving sustained virological response (SVR) can be determined on the basis of the magnitude of HCV viral decline over the first 4 weeks of Peg-IFN/RBV treatment of HIV/HCV co-infected patients who fail to achieve a rapid virological response (RVR).

METHODS

HIV patients co-infected with HCV genotype 1 naïve to Peg-IFN/RBV treatment were included. HCV viral decline from baseline to week 4 was graded. The positive predictive value (PPV) for SVR was evaluated according to the magnitude of HCV viral decline at week 4.

RESULTS

One hundred and fifty patients were included. Thirty-four (22.6%) patients achieved RVR, 33 of these (PPV [CI 95%]; 97.05% [86.34-99.85]) achieved SVR. In those patients who did not achieve RVR, the probability to achieving SVR was graded according to the magnitude of viral decline at week 4 (>2 log10 [55.5%], >2.5 log10 [73.3%] and >3 log10 [75%]). The combination of undetectable and magnitude of decline (>2.5 log10) had a PPV for SVR of 89.8% (CI 95%; 0.794-0.964).

CONCLUSIONS

The combination of undetectable HCV viral load and magnitude of decline at week 4 has a high PPV for SVR and identified a higher number of potential Peg-IFN/RBV responders.

Biochemical interaction of anti-HCV telaprevir with the ABC transporters P-glycoprotein and breast cancer resistance protein

Background

The ATP-binding cassette (ABC) transporters P-glycoprotein (P-gp)/ABCB1 and breast cancer resistance protein (BCRP)/ABCG2 are involved in the intestinal absorption and renal excretion of various substrate drugs. Their activities affect sub-therapeutic drug concentrations and excretion of natural transporter substrates. The new oral anti-HCV drug telaprevir has dramatically improved the efficacy of hepatitis-C virus (HCV) treatment, and recent studies have suggested a possible pharmacological interaction between telaprevir and P-gp. We studied the kinetics of in vitro interactions between telaprevir and P-gp and BCRP to understand the molecular basis of that interaction.

Findings

The effect of telaprevir on P-gp- and BCRP-mediated transport was evaluated by an in vitro vesicle transporter assay using different transport substrates, and the kinetics of transporter inhibition was determined. The results showed that telaprevir could inhibit P-gp- and BCRP-mediated transport in the in vitro vesicle transport assay, with each IC₅₀ values of ≈ 7 μmol/L and ≈ 30 μmol/L, respectively. Analyses of Lineweaver–Burk plots showed that telaprevir was likely to be a competitive inhibitor against P-gp and BCRP. Photoaffinity labeling experiments were employed to observe competitive inhibition by telaprevir using iodoarylazidoprazosin (IAAP) as a binding substrate for P-gp and BCRP. These experiments revealed that telaprevir inhibited [¹²⁵I]-IAAP-binding with P-gp and BCRP.

Conclusion

Telaprevir competitively inhibited P-gp and BCRP, and P-gp-mediated transport was more sensitive to telaprevir compared with BCRP-mediated transport. These data suggest that telaprevir represses the transporter functions of P-gp and BCRP via direct inhibition.

Protease inhibitors for hepatitis C: economic implications

Chronic hepatitis C virus (HCV) infection, a blood-borne virus, is the leading cause of chronic liver disease and liver transplantation worldwide. Chronic HCV infection is usually asymptomatic in the early stages of the disease, making an estimation of the total population affected difficult to elicit. The gold standard treatment option to date has been a combination of pegylated interferon and ribavirin. Recent developments have led to the introduction of two protease inhibitors for use in chronic HCV-boceprevir and telaprevir. Phase III studies have shown both agents have the potential to significantly increase the probability of attaining a sustained virologic response (the primary outcome of interest in chronic HCV) in genotype 1 infections. However, the added cost of these agents also presents the need for decision makers to determine their place on drug formularies. The protease inhibitors are to be administered as triple therapy with the existing gold standard. However, significant variation exists as to the proposed duration of triple therapy, use of lead-in pegylated interferon and ribavirin and subsequent pegylated interferon therapy after finishing the course of triple therapy. Treatment algorithms also exist for the use of stopping rules in the case of early non-responders.The aim of this review is to highlight the current understanding of the economic impact protease inhibitors may have on health care systems and considerations required in the treatment of HCV. Economic and health-related quality of life issues are addressed from multiple viewpoints. The major aspects of the economic evaluations, to date, that included triple therapy as an alternative in the treatment of chronic HCV are brought to light. Future economic evaluations in alternative settings would be useful. The review also emphasizes the challenges for future research. This includes the potential for new therapies to no longer require inclusion of pegylated interferon and/or ribavirin, as well as the use of protease inhibitors in non-genotype 1 patients or those with significant co-morbidities such as HIV/AIDS.

Telaprevir in HIV/HCV-coinfected patients: a new standard with a short half-life

The licensing of the first HCV protease inhibitors will lead to a dramatic increase in cure rates for patients with chronic genotype 1 hepatitis C. The addition of a third drug, such as telaprevir, to the standard treatment with pegylated interferon and ribavirin has become the new standard of care in the western world. While a shortening of the treatment duration is often possible, side effects are likely to increase with these products. The experience with telaprevir in HIV/HCV-coinfected patients is limited to one Phase II trial. Nevertheless, HIV-positive patients are in urgent need for new treatment options, as they often have more aggressive liver disease and lower reponse rates with the current standard treatments. These initial results are very promising, and HIV/HCV-coinfected patients seem to now have equal response rates as monoinfected patients, as long as drug–drug interactions remain under control.

Multiplex liquid chromatography-tandem mass spectrometry assay for simultaneous therapeutic drug monitoring of ribavirin, boceprevir, and telaprevir

New directly acting antivirals (DAAs) that inhibit hepatitis C virus (HCV) replication are increasingly used for the treatment of chronic hepatitis C. A marked pharmacokinetic variability and a high potential for drug-drug interactions between DAAs and numerous drug classes have been identified. In addition, ribavirin (RBV), commonly associated with hemolytic anemia, often requires dose adjustment, advocating for therapeutic drug monitoring (TDM) in patients under combined antiviral therapy. However, an assay for the simultaneous analysis of RBV and DAAs constitutes an analytical challenge because of the large differences in polarity among these drugs, ranging from hydrophilic (RBV) to highly lipophilic (telaprevir [TVR]). Moreover, TVR is characterized by erratic behavior on standard octadecyl-based reversed-phase column chromatography and must be separated from VRT-127394, its inactive C-21 epimer metabolite. We have developed a convenient assay employing simple plasma protein precipitation, followed by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) for the simultaneous determination of levels of RBV, boceprevir, and TVR, as well as its metabolite VRT-127394, in plasma. This new, simple, rapid, and robust HPLC-MS/MS assay offers an efficient method of real-time TDM aimed at maximizing efficacy while minimizing the toxicity of antiviral therapy.

Statin therapy improves response to interferon alfa and ribavirin in chronic hepatitis C: a systematic review and meta-analysis

The treatment of interferon alfa (IFN-α) and ribavirin for chronic hepatitis C virus (HCV) infection achieves limited sustained virological response (SVR). We conducted a systematic review and meta-analysis to explore the efficacy of adding statins to IFN-α and ribavirin therapy for chronic hepatitis C. Studies with data pertinent to the effect of statins on chronic hepatitis C were reviewed, and randomized controlled trials (RCTs) evaluating the efficacy of the addition of statins to IFN-α and ribavirin were included in meta-analysis. The primary outcome measure was SVR. Secondary outcome measures were rapid virological response (RVR) and early virological response (EVR). The literature was systematically searched through October 2012. After screening of the 1724 non-duplicated entries, 54 potentially relevant studies were fully reviewed. Of those, 18 studies were relevant and 5 RCTs met the inclusion criteria for meta-analysis. In comparison with IFN-α and ribavirin therapy, the addition of statins significantly increased SVR (OR=2.02, 95% CI: 1.38-2.94), RVR (OR=3.51, 95% CI: 1.08-11.42) and EVR (OR=1.89, 95% CI: 1.20-2.98). The SVR increase remained significant for HCV genotype 1 (OR=2.11, 95% CI: 1.40-3.18). There were no significant increases in adverse events and withdrawals with the addition of statins. In conclusion, the addition of statins to IFN-α and ribavirin improves SVR, RVR, and EVR without additional adverse events and thus may be considered as adjuvant to IFN-α and ribavirin for chronic hepatitis C. Statins might also be used for HCV genotypes other than genotype 1, or in patients in whom the use of protease inhibitors is contraindicated or not indicated.

Natural killer KIR3DS1 is closely associated with HCV viral clearance and sustained virological response in HIV/HCV patients

Aim

To evaluate the influence of the presence of the killer cell immunoglobulin-like receptor (KIR) 3DS1 on HCV treatment response in HIV/HCV genotype 1 co-infected patients

Methods

HIV/HCV co-infected patients were included. KIR3DS1, their specific HLA-B ligands and IL28B gene were genotyped. Reductions of plasma HCV RNA levels between baseline and week 1, week 2 and week 4 were analyzed for IL28B genotype and KIR3DS1 (HLA Bw4 or Bw6). Rapid and sustained virological response (RVR and SVR) rates were also analyzed.

Results

Sixty HIV/HCV genotype 1 co-infected patients were included. Patients with KIR3DS1 and Bw4 had higher rates of HCV viral decline than those who were not carriers of KIR3DS1 (week1: p = 0.01; week2: p = 0.038; week 4: p = 0.03). Patients carrying KIR3DS1/Bw4 had higher rates of RVR and SVR than those who did not carry KIR3DS1 (RVR: 46.15% versus 17.02%, p = 0.012; SVR: 63.6% versus 13 26.5%, p = 0.031). With respect to patients carrying the IL28B-CC genotype, those with KIR3DS1/Bw4 had greater rates of HCV viral clearance (week1: p<0.001; week2: p = 0.01; week 4: p = 0.02), RVR (p = 0.015) and SVR (p = 0.029) than those not carrying KIR3DS1.

Conclusion

Our results show that the KIR3DS1 genotype has a positive effect on HCV viral clearance during the first weeks of Peg-IFN/RBV treatment in HCV/HCV co-infected patients bearing genotype 1, and higher RVR and SVR rates.

Safety aspects of protease inhibitors for chronic hepatitis C: adverse events and drug-to-drug interactions

The standard of care therapy of chronic hepatitis C with the combination of pegylated interferon and ribavirin for 24 or 48 weeks was a remarkable accomplishment of the past decade. However, sustained virological responses rates of about 80% (genotypes 2–3) and 50% (genotype 1) were not satisfactory especially for patients infected with genotype 1. Important advances in the biology of HCV have made possible the development of the direct-acting antiviral agents boceprevir and telaprevir with substantial increase in the rates of sustained virological response with shorter duration of therapy for a large number of patients. However, the complexity of triple therapy is higher and several new side effects are expected suggesting greater expertise in the patient management. Anemia and disgeusia are frequent with boceprevir while cutaneous rash, ranging from mild to severe, is expected with telaprevir. Higher risk of drug–drug interactions demand further clinical consideration of the previous well-known adverse events of pegylated interferon and ribavirin. Identification and prompt management of these potential new problems with boceprevir and telaprevir are crucial in clinical practice for optimizing treatment and assuring safety outcomes to HCV-genotype 1 patients.

Absolute and relative contraindications to pegylated-interferon or ribavirin in the US general patient population with chronic hepatitis C: results from a US database of over 45 000 HCV-infected, evaluated patients

BACKGROUND

Chronic hepatitis C (HCV) treatment with pegylated-interferon (PEG-IFN)/ribavirin (RBV) is often limited by preexisting medical, psychiatric and psychosocial contraindications. However, limited data exist in general patient populations.

AIM

To evaluate the percentage of HCV-infected patients in the general US population who may have contraindications to PEG-IFN/RBV.

METHODS

The General Electric (GE) Centricity dataset was used to screen the US population between 2004 and 2009 for HCV infection and contraindications to PEG-IFN/RBV. HCV diagnosis and contraindications were identified using ICD-9-CM codes or laboratory values. Only patients with an encounter 180 days prior to HCV diagnosis were included. Demographic differences were calculated using Pearson's chi-squared test. Frequencies and percentages for absolute and relative contraindications to PEG-IFN and/or RBV were determined and proportions and rates/1000 person-months were calculated.

RESULTS

A total of 15 561 021 patients were screened, and 45 690 (0.3%) were HCV-positive and were evaluated. Those with contraindications were significantly younger, female, White, not currently married and receiving Medicare or Medicaid coverage (all P < 0.0001). 17.3% had at least one contraindication to PEG-IFN/RBV (5.5 events/1000 person-months); bipolar disorder (6.5%), anaemia (Hgb < 10 g/dL; 5.9%), pregnancy (1.9%) and neutropenia (neutrophils <750 cells/mm(3) ; 1.2%) were most frequently cited.

CONCLUSIONS

Approximately, 17% of HCV-infected patients in the general US population had at least one contraindication to PEG-IFN/RBV. Most contraindications were relative and potentially modifiable. Clinical assessment of contraindications as relative and/or modifiable should be considered and used to determine if patients could benefit from current PEG-IFN-containing triple therapy or future PEG-IFN- or RBV-free regimens.

CIHR Canadian HIV Trials Network Coinfection and Concurrent Diseases Core: Canadian guidelines for management and treatment of HIV/hepatitis C coinfection in adults

BACKGROUND

Hepatitis C virus (HCV) coinfection occurs in 20% to 30% of Canadians living with HIV, and is responsible for a heavy burden of morbidity and mortality. HIV-HCV management is more complex due to the accelerated progression of liver disease, the timing and nature of antiretroviral and HCV therapy, mental health and addictions management, socioeconomic obstacles and drug-drug interactions between new HCV direct-acting antiviral therapies and antiretroviral regimens.

OBJECTIVE

To develop national standards for the management of HCV-HIV coinfected adults in the Canadian context.

METHODS

A panel with specific clinical expertise in HIV-HCV co-infection was convened by The CIHR HIV Trials Network to review current literature, existing guidelines and protocols. Following broad solicitation for input, consensus recommendations were approved by the working group, and were characterized using a Class (benefit verses harm) and Level (strength of certainty) quality-of-evidence scale.

RESULTS

All HIV-HCV coinfected individuals should be assessed for HCV therapy. Individuals unable to initiate HCV therapy should initiate antiretroviral therapy to slow liver disease progression. Standard of care for genotype 1 is pegylated interferon and weight-based ribavirin dosing plus an HCV protease inhibitor; traditional dual therapy for 24 weeks (for genotype 2/3 with virological clearance at week 4); or 48 weeks (for genotypes 2-6). Therapy deferral for individuals with mild liver disease may be considered. HIV should not be considered a barrier to liver transplantation in coinfected patients.

DISCUSSION

Recommendations may not supersede individual clinical judgement.

Who needs direct-acting antivirals for HCV? Challenges faced in advancing HCV therapy for HIV-HCV-coinfected individuals

BACKGROUND

The recent availability of new direct-acting antivirals (DAAs) for HCV treatment, which significantly increase sustained virological response rates for genotype 1 HCV infection, has brought new optimism with respect to curative HCV treatment for HIV-HCV-coinfected patients. We describe the characteristics of coinfected patients who could be eligible for DAAs to determine potential challenges facing clinicians and patients hoping to take advantage of these new therapies.

METHODS

We evaluated the sociodemographic and clinical characteristics of the genotype 1 HCV-HIV-infected participants in a Canadian prospective multicentre cohort study at their most recent visit to assess potential eligibility for combination HCV treatment with boceprevir or telaprevir.

RESULTS

Of the 1,020 coinfected participants enrolled in the cohort, 707 (85%) had evidence of chronic HCV infection (HCV-RNA-positive), of whom 497 (70%) were infected with genotype 1; 375 (75%) were naive to HCV treatment and 122 (25%) had previously received therapy and failed. Only 143 (38%) of HCV treatment-naive and 39 (32%) of treatment-experienced participants had no absolute contraindications for treatment. Alcohol abuse, active depression and decompensated liver disease were the most frequent reasons for treatment ineligibility. The majority would require alterations in antiretroviral regimens to avoid important drug-drug interactions.

CONCLUSIONS

Although the need for curative HCV therapy in HIV-HCV coinfection is great, the actual number of patients who could be eligible for DAAs at the present time may be quite low. There remains an urgent need to develop safe, simple and interferon-sparing treatments for coinfected individuals.

Effect of maintenance immunosuppressive drugs on virus pathobiology: evidence and potential mechanisms

Recent evidence suggesting a potential anti-CMV effect of mTORis is of great interest to the transplant community. However, the concept of an immunosuppressant with antiviral properties is not new, with many accounts of the antiviral properties of several agents over the years. Despite these reports, to date, there has been little effort to collate the evidence into a fuller picture. This manuscript was developed to gather the evidence of antiviral activity of the agents that comprise a typical immunosuppressive regimen against viruses that commonly reactivate following transplant (HHV1 and 2, VZV, EBV, CMV and HHV6, 7, and 8, HCV, HBV, BKV, HIV, HPV, and parvovirus). Appropriate immunosuppressive regimens posttransplant that avoid acute rejection while reducing risk of viral reactivation are also reviewed. The existing literature was disparate in nature, although indicating a possible stimulatory effect of tacrolimus on BKV, potentiation of viral reactivation by steroids, and a potential advantage of mammalian target of rapamycin (mTOR) inhibition in several viral infections, including BKV, HPV, and several herpesviruses.

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.

A Phase I, randomized, placebo-controlled, 3-day, ascending-dose study of GS-9451, an NS3/4A protease inhibitor, in genotype 1 hepatitis C patients

BACKGROUND

GS-9451 is a novel inhibitor of the HCV NS3/4A protease and demonstrates potent in vitro suppression of HCV genotype 1 replicons.

METHODS

The safety, pharmacokinetics and antiviral efficacy of GS-9451 were evaluated in a Phase I study in treatment-naive, HCV genotype-1-infected patients. Patients were randomized to 3 days of once-daily dosing with placebo (n=8) or GS-9451 60 mg (n=8 genotype 1a), 200 mg (n=8 genotype 1a; n=8 genotype 1b) or 400 mg (n=9 genotype 1a). Plasma samples were collected up to and on day 14 for pharmacokinetic evaluation, serum HCV RNA quantitation and NS3 sequencing.

RESULTS

No patients interrupted or discontinued dosing because of an adverse event. The median (range) maximal HCV RNA reductions from baseline were -0.88 (-1.24- -0.64), -3.19 (-3.31- -2.94) and -3.64 (-4.08- -3.54) log10 IU/ml in genotype 1a patients receiving 60, 200 and 400 mg/day GS-9451, respectively, and -3.48 (-3.54- -3.03) log10 IU/ml in genotype 1b patients receiving GS-9451 200 mg/day. Median half-life ranged from 14 to 17 h. Day 3 mean concentration at the end of dosing interval was 5.5- and 17-fold above protein-binding adjusted mean 50% effective inhibitory concentration in 200 mg and 400 mg cohorts, respectively. No resistance mutations were detected with GS-9451 60 mg/day. In the 200 mg/day or 400 mg/day groups, predominant mutations were NS3 R155 (R155K) in genotype 1a patients and D168 (D168E, D168V and D168G) in genotype 1b patients.

CONCLUSIONS

GS-9451 was well-tolerated. During 3 days of monotherapy, GS-9451 200 mg/day or 400 mg/day demonstrated potent antiviral activity in both HCV genotype 1a- and 1b-infected patients. GS-9451 is currently being evaluated in combination regimens with and without pegylated interferon-α.

Boceprevir: a protease inhibitor for the treatment of hepatitis C

BACKGROUND

Boceprevir is a protease inhibitor indicated for the treatment of chronic hepatitis C virus (HCV) genotype 1 infection in combination with peginterferon and ribavirin for treatment-naive patients and those who previously failed to improve with interferon and ribavirin treatment.

OBJECTIVE

This article provides an overview of the mechanism of action, pharmacologic and pharmacokinetic properties, clinical efficacy, and tolerability of boceprevir.

METHODS

Relevant information was identified through a search of PubMed (1990-July 2012), EMBASE (1990-July 2012), International Pharmaceutical Abstracts (1970-July 2012), and Google Scholar using the key words boceprevir, SCH 503034, non-structural protein 3 (NS3) serine protease inhibitor, and direct-acting antiviral agent (DAA). Additional information was obtained from the US Food and Drug Administration's Web site, review of the reference lists of identified articles, and posters and abstracts from scientific meetings.

RESULTS

Clinical efficacy of boceprevir was assessed in 2 Phase III trials, Serine Protease Inhibitor Therapy-2 (SPRINT-2) for treatment-naive patients and Retreatment with HCV Serine Protease Inhibitor Boceprevir and PegIntron/Rebetol 2 (RESPOND-2) for treatment-experienced patients. In SPRINT-2, patients were randomized to receive peginterferon + ribavirin (PR) or peginterferon + ribavirin + boceprevir (PRB); duration of boceprevir therapy varied from 24, 32, to 44 weeks on the basis of HCV RNA results. The primary endpoint was achievement of sustained virologic response (SVR; lower limit of detection, 9.3 IU/mL). The addition of boceprevir was shown to be superior, with overall SVR rates ranging from 63% to 66% compared with 38% with PR (P < 0.001). Results of SVR in SPRINT-2 were also reorganized to monitor SVRs in black and non-black patients. Treatment-experienced patients were assessed in RESPOND-2; however, null responders were excluded. Patients were again randomized to PR or PRB; duration of boceprevir therapy varied from 32 to 44 weeks on the basis of HCV RNA results. SVR was significantly higher in patients receiving boceprevir (59%-66% vs 21% with PR; P < 0.001). This benefit was seen in both previous nonresponders (SVR, 40%-52% vs 7% with PR), as well as previous relapsers (SVR, 69%-75% vs 29% with PR). Importantly, SVR could be attained with a shortened course of therapy in almost one half of all treated patients in SPRINT-2 (44%) and RESPOND-2 (46%).

CONCLUSIONS

Boceprevir was well tolerated in clinical trials and a welcomed addition to our HCV armamentarium.

Telaprevir: a review of its use in the management of genotype 1 chronic hepatitis C

Telaprevir (Incivo®, Incivek®), an orally administered inhibitor of the hepatitis C virus non-structural protein NS3-4A serine protease, is used in combination with pegylated interferon (peginterferon)-alpha and ribavirin in the treatment of adults with genotype 1 chronic hepatitis C virus (HCV) infection (chronic hepatitis C). This article reviews data on the clinical efficacy and tolerability of telaprevir in adults with genotype 1 chronic hepatitis C and provides a summary of its pharmacological properties. In in vitro studies, telaprevir shows good activity against genotype 1 HCV, including viral isolates from patients with chronic hepatitis C. Numerous resistant variants of HCV have been identified in clinical isolates from patients receiving treatment with telaprevir-based therapy. However, the clinical relevance of viral variants emerging during treatment requires further study. Telaprevir administered for 12 weeks in combination with peginterferon-alpha-2a and ribavirin for up to 48 weeks was effective in the treatment of previously untreated or previously treated adults with genotype 1 chronic hepatitis C in three major randomized phase III trials. Sustained virological response rates (i.e. percentages of patients with undetectable HCV RNA levels 24 weeks after the last planned dose of study medication: the primary endpoint) achieved with the telaprevir-based regimens were significantly higher than those produced with peginterferon-alpha-2a and ribavirin alone (the 'current standard of care'). In the largest trial (the ADVANCE trial) in previously untreated patients, 24 weeks after the last planned dose of study drug, recipients of 12 weeks' treatment with telaprevir in combination with peginterferon-alpha-2a and ribavirin followed by treatment with peginterferon-alpha-2a and ribavirin for a further 12 or 36 weeks experienced significantly (p < 0.001) higher sustained virological response rates than patients who received peginterferon-alpha-2a and ribavirin dual therapy for 48 weeks (75% vs 44%). Adverse events were reported more frequently with telaprevir-based regimens than with peginterferon-alpha-2a and ribavirin dual therapy in the major trials. The most common adverse events included fatigue, rash, pruritus, anaemia and nausea. In conclusion, telaprevir in combination with peginterferon-alpha and ribavirin is an effective treatment for treatment-naive and previously treated adults with genotype 1 chronic hepatitis C - patient groups in whom peginterferon-alpha and ribavirin dual therapy may not be successful. Thus, telaprevir is a valuable new treatment option for use in combination with peginterferon-alpha and ribavirin in treatment-naive or previously treated adults with genotype 1 chronic hepatitis C.

[Current indications for triple therapy in hepatitis C virus infection]

Chronic hepatitis C virus (HCV) infection is the main cause of liver cirrhosis and liver carcinoma in western countries. There is evidence that HCV clearance induced by antiviral therapy is beneficial, increasing survival and reducing the complications of cirrhosis. Triple therapy with boceprevir or telaprevir associated with pegylated interferon and ribavirin has increased rates of sustained viral response both in treatment-naïve patients and in those failing previous regimens. Before treating patients with these new molecules, physicians should be familiar with their indications and the regimens to be used. Furthermore, both adverse events and the development of resistances must be monitored. The main aims are careful selection of patients and of the regimen to be used, and achieving adequate adherence to obtain optimal results.