Boceprevir for previously treated chronic HCV genotype 1 infection

Management of side-effects

The current treatment of chronic hepatitis C is the triple combination of pegylated interferon, ribavirin and a new direct-acting antiviral [either telaprevir (TVR) or boceprevir (BOC)]. This new association produces better viral response rates, but may induce or enhance adverse events, which can lead to discontinuation of treatment. TVR regimens are associated with an increased risk of dermatological side-effects such as rash, albeit generally mild. In these cases, optimal skincare treatments, including emollient creams and topical corticosteroids, allow the continuation of antiviral treatment. In a minority of cases, the rash may be severe and life-threatening, leading to immediate discontinuation of all treatments. The goal for the physician is to differentiate severe cutaneous adverse reactions (SCARs), including DRESS (drug reactions with eosinophilia and systemic symptoms). Anaemia is also more frequent with triple combinations using TVR or BOC. The management of anaemia requires the use of erythropoietin alpha (EPO) and the need to decrease ribavirin doses. Thus, monitoring haemoglobin has to be more frequent in difficult-to-treat patients such as cirrhosis cases; nevertheless, despite the use of EPO and ribavirin-dose adaptation, blood transfusion is sometimes still required. Thus, triple combination therapy with a DAA is effective, but it increases the rate of adverse events, and adds to the well-known adverse effects of pegylated interferon and ribavirin. This suggests the need for a different clinical and biological management of patients treated with the triple combination.

Antiviral activity of telaprevir and boceprevir for the treatment of hepatitis C virus infection in treatment-experienced patients

Around 50% of hepatitis C virus (HCV)-positive patients infected with genotype 1 are nonresponders to the combination of pegylated interferon (pegIFN) and ribavirin, including relapsers, and partial and null responders and, as such, are exposed to the risk of progression to cirrhosis and its complications, resulting in HCV-related morbidity and mortality. Repeat treatment using the same combination in such patients results in <5% viral eradication and there are no therapeutic prospects for patients who fail, as maintenance therapy has not proved efficacious. The triple association of direct-acting antivirals specific of HCV, and especially the first-generation protease inhibitors boceprevir and telaprevir, increases this percentage to around 65%, with variations according to the previous response to therapy of patients (85% of relapsers, 50% of partial responders and 30% of null responders). These encouraging results extend the therapeutic indications and costs of therapy during virological follow-up, and influence the rules of discontinuation. Information on the management of these new molecules also allows a larger number of patients to be cured and reduces the occurrence of viral resistance. Thus, the aim of the present review is to summarize the efficacy of the triple association of pegIFN, ribavirin and telaprevir or boceprevir in treatment-experienced patients who failed to respond to dual pegIFN and ribavirin therapy.

Side-effects of pegylated interferon plus ribavirin therapy with or without protease inhibitor direct acting antiviral agents during treatment of chronic hepatitis C virus infection

Hepatitis C virus (HCV) infection affects 2–3% of the population, approximately 170 million people worldwide, causing chronic HCV-related hepatitis with subsequent liver cirrhosis, hepatic failure, hepatocellular cancer, and liver-related mortality in a large number of patients. The gold standard therapy, pegylated interferon alpha in combination with ribavirin can eradicate hepatitis C virus infection in approx. 40% of treatment-naïve patients infected with HCV genotype G1, and only 15–20% of patients with previous treatment. Success rate is substantially improved with the development and registration of two direct acting anti-hepatitis C virus protease inhibitors (boceprevir and telaprevir) in the second decade of 21st century: combined with the standard therapy, almost three quarter of previously untreated, and more than half of previously unsuccessfully treated patients can achieve sustained viral response with protease inhibitor based triple therapies. A major barrier to successful treatment is the association of peginterferon/ribavirin therapy with frequent and sometimes serious adverse effects. In clinical trials, approximately 10–15% of treated patients discontinue peginterferon and ribavirin due to adverse events; however, in routine clinical practice, the rate of treatment discontinuation has been reported to be substantially higher. The side effects of peginterferon/ribavirin therapy affect virtually all organ systems, and addition of protease inhibitor can amplify these side effects (particularly anemia), and/or may lead to new ones (i.e., dysgeusia with boceprevir or skin rush with telaprevir). There is considerable regional and global variability in the nature and prevalence of these adverse effects as well as in the best strategies to ameliorate their impact on hepatitis C virus treatment. This article summarizes the side effects of dual and triple therapies and their management based on the labels of the drugs, on a comprehensive literature review, as well as on the recently published opinion of an international panel of experts – with the provision of providing help for the physicians treating hepatitis C virus infection to achieve the best possible success with the highest possible safety for the patients. Orv. Hetil., 2011, 152, 1997–2009.

Alteration of hepatic nuclear receptor-mediated signaling pathways in hepatitis C virus patients with and without a history of alcohol drinking

The current study tests a hypothesis that nuclear receptor signaling is altered in chronic hepatitis C patients and that the altered pattern is specific to alcohol drinking history. The expression of a panel of more than 100 genes encoding nuclear receptors, coregulators, and their direct/indirect targets was studied in human livers. Gene expression pattern was compared between 15 normal donor livers and 23 hepatitis C virus (HCV) genotype 1-positive livers from patients without a drinking history (matched for age, sex, and body mass index). HCV infection increased the expression of nuclear receptors small heterodimer partner and constitutive androstane receptor (CAR) as well as genes involved in fatty acid trafficking, bile acid synthesis and uptake, and inflammatory response. However, the expression of retinoid X receptor (RXR) α, peroxisomal proliferator-activated receptor (PPAR) α and β as well as steroid regulatory element-binding protein (SREBP)-1c was decreased in HCV-infected livers. Gene expression pattern was compared in chronic hepatitis C patients with and without a drinking history. Alcohol drinking increased the expression of genes involved in fatty acid uptake, trafficking, and oxidation, but decreased the expression of genes responsible for gluconeogenesis. These changes were consistent with reduced fasting plasma glucose levels and altered expression of upstream regulators that include RXRα, PPARα, and CAR. The messenger RNA levels of fibroblast growth factor 21, interleukin-10, and fatty acid synthase, which are all regulated by nuclear receptors, showed independent correlation with hepatic HCV RNA levels.

CONCLUSION

Our findings suggest that those genes and pathways that showed altered expression could potentially be therapeutic targets for HCV infection and/or alcohol drinking-induced liver injury.

Management of treatment with direct-acting antiviral (DAA) in clinical practice

The triple therapy has brought about a genuine revolution in the care of patients with chronic hepatitis C virus infection, although achieving a high cure rate requires adding disciplines beyond the attending physician when confronted by a motivated patient. The treatment is complex because of the many parameters involved (such as fibrosis score, patient's history of previous antiviral treatment and viral kinetics during treatment). A working knowledge of drug interactions and contraindications for drugs other than antiviral therapy is required, as well as meticulous follow-up.

Direct-acting antivirals for hepatitis C virus infections in patients co-infected with human immunodeficiency virus

Nearly three-quarters of human immunodeficiency virus-hepatitis C virus (HIV-HCV) coinfected patients in France currently need to be cured of their chronic HCV infection. The increase in sustained virological response rates obtained with the recently available HCV protease inhibitors in treatment-naïve genotype-1 patients has generated considerable hope in these co-infected patients. However, several particularities (such as a higher baseline HCV load, more advanced liver fibrosis, frequent co-morbidities, and the risk of toxicity and drug-drug interactions) have not allowed the direct extrapolation of the results observed in HCV-monoinfected patients to patients with HIV-HCV co-infection. Yet, despite these uncertainties and the little available data from ongoing trials, several proposals can be made not only because the patients and drugs are ready and waiting, but also because the clock is ticking. In general, it can be advocated that HCV triple therapy should be offered to most HIV-infected patients with advanced liver fibrosis, but should be deferred or discussed on a case-by-case basis in those with mild-to-moderate fibrosis. However, such proposals rely on a relatively small amount of evidence and many questions are still pending, as studies in HIV-HCV co-infected patients have been late in coming and are several years behind those in HCV-monoinfected patients. Thus, this situation, in the context of more rapid and more severe infection, and lower response rates with standard care (pegylated interferon and ribavirin), along with the many potential drug-drug interactions (particularly with antiretroviral therapy), underscores the need for earlier evaluation of new strategies, schedules and new direct-acting antivirals in HIV-infected patients.

Challenges and opportunities for hepatitis C drug development in HIV-hepatitis C virus-co-infected patients

The approval of the first direct-acting antivirals (DAAs) against the hepatitis C virus (HCV) has been eagerly expected for treating chronic hepatitis C in HIV individuals given that progression to cirrhosis and end-stage liver disease occurs faster in the co-infected population. The appropriate and judicious use of DAAs may provide cure to a large number of HIV-HCV patients. On the contrary, the widespread use of DAAs will occasionally be off-label or under unsatisfactory medical conditions, which may result in undesirable toxicities, drug interactions or selection of drug resistance in HCV. As a result of using first-generation DAAs in HIV-HCV-co-infected patients, a growing proportion of the remaining hepatitis C individuals will be those harboring non-HCV 1 genotypes or drug-resistant HCV variants. Over time, the largest reservoir of HCV genotype 1 patients will accumulate in resource-poor nations where access to hepatitis C therapy has been elusive and HIV treatment remains the primary health issue for the co-infected population.

Evaluation of pharmacokinetics, user handling, and tolerability of peginterferon alfa-2a (40 kDa) delivered via a disposable autoinjector device

BACKGROUND

Peginterferon alfa-2a (40 kDa) is currently administered using a prefilled syringe. The peginterferon alfa-2a disposable autoinjector is a new safety-engineered device designed to facilitate injection and reduce the risk of needlestick injuries. The analysis of two open-label Phase I trials evaluated the pharmacokinetics, successful administration, and tolerability of peginterferon alfa-2a when using the autoinjector. The studies were performed to support the filing and registration of the autoinjector device.

METHODS

In trial 1, 50 healthy adult subjects received one 180 μg dose of peginterferon alfa-2a via the autoinjector. Serial blood samples were collected predose, up to 336 hours following drug administration, and at follow-up (28 ± 3 days post-dosing) for noncompartmental pharmacokinetic analysis. Trial 2 randomized 60 adult patients with chronic hepatitis C to 180 μg peginterferon alfa-2a once weekly by the autoinjector or prefilled syringe for 3 weeks followed by the alternative device (prefilled syringe or autoinjector, respectively) for 3 weeks. Patients also received ribavirin. Administration by the devices was evaluated under direct observation by a study staff member and by patient subjective assessment.

RESULTS

In trial 1, following a single dose of peginterferon alfa-2a, the maximum plasma concentration was 16.1 ± 5.3 ng/mL (mean ± standard deviation), and area under the concentration time curve (0-168 hours) was 1996 ± 613 ng · hour/mL, similar to that reported using a vial/syringe or prefilled syringe. In trial 2, few patients showed handling difficulties with either device. Generally, patients were observed to be more satisfied and confident, followed instructions better, and successfully initiated injection with the autoinjector versus the prefilled syringe. Patients reported the autoinjector to be more convenient and easier to use. No pain or discomfort was experienced using the autoinjector. The autoinjector safety profile was consistent with that known for peginterferon alfa-2a/ribavirin.

CONCLUSION

These results indicate that peginterferon alfa-2a can be successfully and safely delivered via the autoinjector and that the device is easy to handle.

The therapeutic approaches for hepatitis C virus: protease inhibitors and polymerase inhibitors

The current standard of care for hepatitis C infection is peginterferon/ribavirin (PegIFN/RBV). We are entering the era where direct-acting antiviral agents (DAAs) will be added to PegIFN/RBV, leading to higher sustained response rates in genotype 1 infected individuals. Currently DAAs are directed toward specific proteins involved in hepatitis C replication with NS3/NS4A protease inhibitors furthest in development. Telaprevir and boceprevir are both NS3/NS4a inhibitors that significantly improve sustained response when added to PegIFN and RBV. The hepatitis C virus (HCV) polymerase inhibitors are another promising DAA class. These molecules are divided into nucleoside/nucleotide polymerase inhibitors and nonnucleotide/nucleoside polymerase inhibitors. Nucleoside/nucleotide polymerase inhibitors have a high barrier to resistance and appear to be effective across a broad range of genotypes. Nonnucleoside polymerase inhibitors have a lower barrier of resistance and appear to be genotype specific. Preliminary data with these compounds are also promising. A third class, NS5A inhibitors, has also shown potent HCV RNA suppression in preliminary studies as monotherapy and with PegIFN and RBV. Combinations of these agents are also entering clinical trials and indeed a preliminary report has demonstrated that the combination of an NS3/4A protease inhibitor and NS5B polymerase inhibitor can effectively suppress virus in genotype 1 individuals. Future studies will concentrate on combinations of direct-acting antiviral agents without and with PegIFN and RBV. Clinicians will need to be familiar with managing side effects as well as resistance as we enter this new era.

Hepatitis C virus epitope exposure and neutralization by antibodies is affected by time and temperature

A recent study with flaviviruses suggested that structural dynamics of the virion impact antibody neutralization via exposure of ostensibly cryptic epitopes. To determine whether this holds true for the distantly related hepatitis C virus (HCV), whose neutralizing epitopes may be obscured by a glycan shield, apolipoprotein interactions, and the hypervariable region on the E2 envelope protein, we assessed how time and temperature of pre-incubation altered monoclonal antibody (MAb) neutralization of HCV. Notably, several MAbs showed increased inhibitory activity when pre-binding was performed at 37°C or after longer pre-incubation periods, and a corresponding loss-of-neutralization was observed when pre-binding was performed at 4°C. A similar profile of changes was observed with acute and chronic phase sera from HCV-infected patients. Our data suggest that time and temperature of incubation modulate epitope exposure on the conformational ensembles of HCV virions and thus, alter the potency of antibody neutralization.

[New treatments of chronic hepatitis C]

The current treatment of chronic hepatitis C since several years, the association of pegylated interferon and ribavirine, allows to obtain a virological eradication in 55% of patients, all genotypes and 45% of those infected with the genotype 1, the most prevalent. The cure, defined by an undetectable viremia 24 weeks after the discontinuation of treatment is associated to a improvement of the prognosis of the patients with a decrease of mortality and morbidity. The development of news antiviral C molecules, efficient against the genotype 1, two protease inhibitors, boceprevir or telaprevir (which approval has been recently obtained), in association with pegylated interferon and ribavirine, allows to obtain a viral eradication in 70 to 75% of cases, with a reduction of treatment duration to 24 weeks in half of patients. This evolution will modify the therapeutic indications, the therapeutic schemas, the virologic follow-up, the risk factors of sustained virological reponse, the tolerance with the appearance of new adverse effects.

Improved responses to pegylated interferon alfa-2b and ribavirin by individualizing treatment for 24-72 weeks

BACKGROUND & AIMS

Guidelines recommend that patients with chronic hepatitis C virus (HCV) infection be treated with pegylated interferon and ribavirin for 24, 48, or 72 weeks, based on their virologic response to treatment. We investigated the effects of treating patients for individualized durations.

METHODS

We treated 398 treatment-naïve patients who had HCV genotype 1 infections with pegylated interferon alfa-2b and ribavirin for 24, 30, 36, 42, 48, 60, or 72 weeks (mean of 39 weeks, termed individualized therapy); the duration of therapy was determined based on baseline viral load and the time point at which HCV RNA levels became undetectable (measured at weeks 4, 6, 8, 12, 24, and 30). Results were compared with those of 225 patients who received standard treatment for 48 weeks (mean of 38 weeks).

RESULTS

Rates of sustained virologic response (SVR) were 55% among patients who received individualized treatment and 48% among those who received standard treatment (P < .0001 for noninferiority). SVR rates, according to the time point at which HCV RNA levels became undetectable, did not differ significantly between groups. Patients with a rapid virologic response (undetectable levels of HCV RNA at week 4) who were treated for 24 to 30 weeks achieved high rates of SVR (86%-88%). Rates of SVR increased among slow responders who first tested negative for HCV RNA at week 24 and were treated for 60 to 72 weeks compared with those treated for 48 weeks (60%-68% vs 43%-44%). The CC polymorphism at IL28B rs129797860 was associated with an increased rate of SVR compared with the CT/TT polymorphism (P < .0001) at baseline but not among patients who had undetectable levels of HCV RNA following treatment.

CONCLUSIONS

Individualizing treatment of patients with chronic HCV genotype 1 infections for 24 to 72 weeks results in high rates of SVR among rapid responders and increases SVR among slow responders.

Impact of IL28B on treatment outcome in hepatitis C virus G1/4 patients receiving response-guided therapy with peginterferon alpha-2a (40KD)/ribavirin

The IL28B genotype is the most important pretreatment predictor of treatment outcome in patients with chronic hepatitis C. The impact of the rs12979860 genotype on relapse was retrospectively evaluated in genotype 1/4 patients who received response-guided therapy with peginterferon alpha-2a 180 μg/week plus ribavirin 1,000/1,200 mg/day in a large, randomized, multicenter study. Patients with a rapid virologic response (RVR: hepatitis C virus [HCV] RNA <50 IU/mL) at week 4 were treated for 24 weeks; those with a slow virologic response (no RVR but undetectable HCV RNA or ≥ 2-log(10) decrease at week 12) were randomized to 48 (group A) or 72 weeks of treatment (group B). Relapse rates were compared by rs12979860 genotype (C/C versus combined T/C or T/T [T/*]) in patients with confirmed end-of-treatment response and known end-of-follow-up status (sustained virologic response [SVR] or relapse). The rs12979860 genotype was determined for 340/551 study participants. In patients with RVR and C/C or T/* genotype, relapse rates were similar (10.7% versus 15.2%). In patients randomized to groups A and B, relapse rates were similar in patients with C/C genotype randomized to group A (26.9%) and group B (20.0%). In contrast, relapse rates in T/* patients differed markedly between groups A and B, overall (42.9% and 18.8%; P < 0.025, respectively) and in those with low (<400,000 IU/mL: 37.5% versus 18.8%) and high (≥ 400,000 IU/mL: 45.0% versus 18.8%) baseline viral loads.

CONCLUSION

The results suggest that the benefits of extended therapy are restricted to patients with a T allele. Relapse rates are highest in patients with T/* genotype and are markedly higher in slow responders treated for 48 weeks compared with 72 weeks.

Drugs in development for chronic hepatitis C: a promising future

INTRODUCTION

The approval of the first direct-acting antiviral (DAA) drugs for treatment of HCV in 2011 has lead to improved sustained viral response rates of up to 79% in treatment-naïve or relapse genotype 1 patients.

AREAS COVERED

Clinical trial data, the clinical skills required for the use of DAA drugs, the use of genetic tests and HCV RNA assays, new small molecules, resistance-associated variants, combinations of two or more DAAs, treatment of special populations, and future directions. The results of the pivotal Phase III trials with telaprevir and boceprevir, including the efficacy, safety and tolerability, drug-drug interactions and management of the most common side-effects. Resistance-associated variant data and treatment strategies implemented to minimize the development of resistance with these first-generation protease inhibitors.

EXPERT OPINION

Combination therapies of protease inhibitors with nucleoside or non-nucleoside polymerase inhibitors, non-structural protein 5A (NS5A) inhibitors and cyclophylin inhibitors are currently underway in regimens that use pegylated interferon and ribavirin or are interferon-free. The explosion of new drug development will probably move the field forward and offer both improved efficacy and tolerability to patients with hepatitis C infections. The use of these drugs ushers in a new era for the treatment of HCV but must be done with care and caution.

Consensus interferon used to treat prior partial-responders to pegylated interferon plus ribavirin

BACKGROUND

The response to pegylated interferon (peg-IFN) plus ribavirin therapy remains less than ideal with 40-50% of treated subjects failing to clear the virus. Moreover, retreatment is only minimally effective. Consensus interferon (c-IFN) has been shown to be efficacious in HCV genotype 1 patients who have failed therapy with peg-IFN.

AIM

To evaluated the response to re-treatment of peg-IFN plus ribavirin partial-responders with c-IFN plus ribavirin.

METHODS

Forty-two subjects who had previously failed to clear virus after treatment with peg-IFN plus ribavirin were treated with c-IFN (15 μg/day) plus ribavirin (800-1,200 mg/day) until 12 months of therapy or a total of six consecutive months of PCR negativity was achieved.

RESULTS

The study population consisted predominantly of males (71%), Caucasians (76%), with African Americans comprising the remaining 24%, subjects with HCV genotype 1 infection (81%) and 21% had cirrhosis by liver biopsy. The overall SVR rate was 29%. The only pretreatment variable that distinguished responders from partial-responders was the serum triglyceride level.

CONCLUSIONS

The use of c-IFN plus ribavirin in the retreatment of prior peg-IFN plus ribavirin partial responders is essentially twice that achieved in prior re-treatment regimens consisting of a second course of peg-IFN plus ribavirin. These results will need to be evaluated against the use of triple therapy consisting of a peg-IFN plus ribavirin and a protease inhibitor. More studies utilizing c-IFN plus ribavirin with either a protease inhibitor or polymerase inhibitor need to be performed as well.

Boceprevir and Telaprevir

Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are sent in print and are also available on-line. Monographs can be customized to meet the needs of a facility. Subscribers to The Formulary Monograph Service also receive access to a pharmacy bulletin board, The Formulary Information Exchange (The F.I.X.). All topics pertinent to clinical and hospital pharmacy are discussed on The F.I.X.

Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service or The F.I.X., call The Formulary at 800-322-4349. The October 2011 monograph topics are on ticagrelor, peginesatide, linaclotide, vemurafenib, and tafluprost. The DUE/MUE is on ticagrelor.

Antiviral drugs for viruses other than human immunodeficiency virus

Most viral diseases, with the exception of those caused by human immunodeficiency virus, are self-limited illnesses that do not require specific antiviral therapy. The currently available antiviral drugs target 3 main groups of viruses: herpes, hepatitis, and influenza viruses. With the exception of the antisense molecule fomivirsen, all antiherpes drugs inhibit viral replication by serving as competitive substrates for viral DNA polymerase. Drugs for the treatment of influenza inhibit the ion channel M(2) protein or the enzyme neuraminidase. Combination therapy with Interferon-α and ribavirin remains the backbone treatment for chronic hepatitis C; the addition of serine protease inhibitors improves the treatment outcome of patients infected with hepatitis C virus genotype 1. Chronic hepatitis B can be treated with interferon or a combination of nucleos(t)ide analogues. Notably, almost all the nucleos(t) ide analogues for the treatment of chronic hepatitis B possess anti-human immunodeficiency virus properties, and they inhibit replication of hepatitis B virus by serving as competitive substrates for its DNA polymerase. Some antiviral drugs possess multiple potential clinical applications, such as ribavirin for the treatment of chronic hepatitis C and respiratory syncytial virus and cidofovir for the treatment of cytomegalovirus and other DNA viruses. Drug resistance is an emerging threat to the clinical utility of antiviral drugs. The major mechanisms for drug resistance are mutations in the viral DNA polymerase gene or in genes that encode for the viral kinases required for the activation of certain drugs such as acyclovir and ganciclovir. Widespread antiviral resistance has limited the clinical utility of M(2) inhibitors for the prevention and treatment of influenza infections. This article provides an overview of clinically available antiviral drugs for the primary care physician, with a special focus on pharmacology, clinical uses, and adverse effects.

Emerging therapies in hepatitis C: dawn of the era of the direct-acting antivirals

The HCV viral life cycle provides targets for drug development at virtually every step, and many new drugs aimed at these targets are currently being developed. Clinical practice takes a major step forward this year with the arrival of telaprevir and boceprevir, which will be added to the current standard of care of pegIFNα/RBV. Patients will need to be monitored closely and counseled extensively, and clinicians will need to learn the new response-guided therapy algorithms with these therapies. Although there remains work to be done in the field of HCV, these therapies will allow many more patients the opportunity to eradicate HCV infection.

Boceprevir: a protease inhibitor for the treatment of chronic hepatitis C

OBJECTIVE

To review the pharmacology, pharmacokinetics, safety, and efficacy of boceprevir, a novel oral hepatitis C virus (HCV) nonstructural 3 (NS3) protease inhibitor for the treatment of chronic HCV infection, specifically, genotype 1.

DATA SOURCES

A literature search was conducted through MEDLINE and EMBASE (1966-May 2011) using the terms boceprevir and SCH 503034. Data from the package insert, abstracts obtained from conferences, and unpublished Phase 2-3 clinical trials, obtained through clinicaltrials.gov, were also reviewed.

STUDY SELECTION AND DATA EXTRACTION

All English-language articles identified from the data sources were evaluated. References from selected articles were used to identify other pertinent citations. Article selection focused on pharmacology, clinical trials, safety analyses, and resistance. Preference was given to human data.

DATA SYNTHESIS

Boceprevir is an oral protease inhibitor that binds to the NS3 protein of HCV, ultimately inhibiting viral intracellular replication. Boceprevir displays linear pharmacokinetics and is rapidly absorbed upon oral administration. In clinical studies of treatment-naïve and treatment-experienced patients, boceprevir, in combination with standard of care (pegylated interferon [Peg-IFN]-α-2b with or without ribavirin) achieved greater sustained viral response (SVR) rates compared to standard of care. Safety analyses showed an increased incidence of adverse effects when boceprevir was used with Peg-IFN-α-2b and ribavirin. The most common adverse events reported include fatigue, headache, nausea, dysguesia, and anemia; the incidence of the latter 2 adverse effects may be increased if boceprevir is added to standard therapy. Additional Phase 2 and 3 studies are currently enrolling participants.

CONCLUSIONS

Boceprevir should be used in combination with Peg-IFN-α-2b and ribavirin in the treatment of chronic HCV genotype 1 infection. The improved response rates achieved with that combination will make boceprevir a viable option compared with other developing and approved NS3 protease inhibitors for treatment-naïve and treatment-experienced nonresponders/relapsers. Additional data are needed to clarify the potential for resistance and drug interactions.

Redefining baseline demographics: the role of genetic testing in hepatitis C virus infection

The current standard of care for hepatitis C virus (HCV) infection is pegylated interferon and ribavirin. Unfortunately, treatment cures at best only 40% to 50% of patients infected with genotype 1 HCV, the most common HCV genotype in Western countries. Treatment is also expensive and is often poorly tolerated. Therefore, the identification of patients most likely to benefit from treatment is clinically important. Genome-wide association studies have recently identified genetic variants, most notably IL28B and ITPA, which will enhance the ability of clinicians to personalize antiviral therapy for HCV infection.

Naives, nonresponders, relapsers: who is there left to treat?

Hepatitis C has a high prevalence in the United States, and the disease burden of HCV will increase over the next 20 to 30 years by many estimates. Trials to evaluate new therapies and optimize the use of triple drug therapies are needed if HCV is to be successfully controlled and its incumbent morbidity and mortality drastically lowered for all groups of patients. With improvements in ability to achieve SVR with agents such as telaprevir and boceprevir, efforts to improve treatment uptake rates and to re-examine the utility of universal or more inclusive screening for chronic hepatitis C are warranted.

Boceprevir: a user's guide

Given its essential role in the process of hepatitis C virus (HCV) replication, the viral NS3/4A serine protease is arguably the most thoroughly characterized HCV enzyme and the most intensively pursued anti-HCV target for drug development thus far. Recent data have demonstrated promise for the NS3 protease inhibitor boceprevir, which, when added to the standard of care peginterferon and ribavirin, improves sustained virological response while shortening duration of therapy in genotype-1-infected individuals. This review discusses the mechanism of action of boceprevir, its effects on HCV, and its viral resistance.

Randomised clinical trial: anti-viral activity of ANA773, an oral inducer of endogenous interferons acting via TLR7, in chronic HCV

BACKGROUND

The ANA773 is an oral prodrug of a small-molecule toll-like receptor (TLR)7 agonist. Preclinical and healthy volunteer clinical studies with ANA773 have demonstrated induction of endogenous interferon-α (IFN-α) of multiple subtypes, which supports the potential utility in the treatment of chronic hepatitis C virus (HCV) infection.

AIM

To examine safety, tolerability, pharmacodynamics, pharmacokinetics and anti-viral activity of ANA773.

METHODS

The ANA773 was investigated in a double-blind, placebo-controlled study in 34 patients chronically infected with HCV of any genotype. Patients were treatment-naïve or had relapsed following previous interferon-based treatment. This dose escalation study was composed of four dose groups (800, 1200, 1600 and 2000mg). In each group, six to eight patients received ANA773 and two received placebo. Patients were dosed with ANA773 every-other-day for either 28 days (800, 1200 or 1600mg) or 10days (2000mg).

RESULTS

Mild to moderate adverse events were reported, with an increase in frequency and intensity with increasing dose. No serious AEs were reported and there were no early discontinuations. There were dose-related increases in various markers of IFN-α response. The mean maximum change in serum HCV RNA level from baseline was -0.34, -0.29, -0.40, -0.97 and -1.26log(10) in the placebo, 800, 1200, 1600 and 2000mg cohorts, respectively. At the 2000mg dose, ANA773 significantly (P=0.037) reduced serum HCV RNA levels (range: 0.14 to -3.10log(10) ).

CONCLUSION

The ANA773 was generally well tolerated and resulted in a dose-related IFN-dependent response leading to a significant decrease in serum HCV RNA levels in the 2000mg dose group.

IL28B polymorphism and genetic biomarkers of viral clearance in hepatitis C virus infection

Infection with hepatitis C virus (HCV) is a major global health issue. Only a small proportion of patients clear the virus spontaneously and the majority develop chronic hepatitis C infection. Chronic hepatitis C is one of the most common causes of advanced liver disease in the western world and is now the leading indication for liver transplantation. Unfortunately, the standard treatment, consisting of pegylated-interferon and ribavirin, is suboptimal. Less than 50% of patients infected with HCV genotype 1 are cured, treatment is costly and is associated with significant toxicity. Therefore, there has been a need to identify accurate predictors of treatment outcome to facilitate treatment decision-making. Four independent genome-wide association studies have recently confirmed an association between genetic variation in the region of the IL28B gene and treatment outcome in HCV-1 patients. Patients who carry the good response variant are two- to three-fold more likely to be cured. The difference in the frequency of the good response variant between patients of different ethnic background explains much of the recognized ethnic disparity in treatment response rates. The IL28B variants are also associated with likelihood of spontaneous clearance of HCV infection. This discovery represents a significant advance in our ability to personalize HCV therapy, as well as suggesting novel avenues for research into viral pathogenesis and therapeutic development.

An overview of emerging therapies for the treatment of chronic hepatitis C

Chronic hepatitis C (CHC) is a leading cause of chronic hepatitis, cirrhosis, liver failure, and hepatocellular carcinoma (HCC) worldwide. Currently, pegylated interferon (Peg-IFN) and ribavirin therapy achieve curative responses in 40% to 80% of patients, depending on genotype. Recognition of new therapeutic targets for HCV therapy has led to development of novel therapies. The purpose of this review is to summarize the status of novel therapeutics for CHC that promise to increase the safety and efficacy of therapy.

Mixing and matching drugs: what makes sense?

The introduction and ongoing development of directly acting antiviral agents (DAAs) and drugs targeting host cell structures will change the management of patients with chronic hepatitis C virus (HCV) infection. The concomitant use of the protease inhibitors telaprevir or boceprevir with the standard of care, a combination of pegylated interferon (PegIFN) and ribavirin, will represent the new standard for the treatment of HCV genotype 1 infection. Contraindications and side effects limit the applicability of interferon-based therapies and motivate the investigation of PegIFN-sparing regimens. Different DAA combinations under investigation are reviewed in this article.

Management of the treatment-experienced patient infected with hepatitis C virus genotype 1: options and considerations

Individuals infected with hepatitis C virus (HCV) are at risk for cirrhosis and/or hepatocellular carcinoma. Treatment of HCV infection has undergone several revisions over the past 15 years and continues to evolve. The current major advance is with the protease inhibitors in addition to pegylated interferon and ribavirin. The emergence of resistance needs to be monitored carefully as newer and more potent drugs are added to the interferon and ribavirin backbone drugs. In addition, adverse events will be more frequent and some novel ones will require special attention.

Telaprevir for retreatment of HCV infection

BACKGROUND

Up to 60% of patients with hepatitis C virus (HCV) genotype 1 infection do not have a sustained virologic response to therapy with peginterferon alfa plus ribavirin.

METHODS

In this randomized, phase 3 trial, we evaluated the addition of telaprevir to peginterferon alfa-2a plus ribavirin in patients with HCV genotype 1 infection who had no response or a partial response to previous therapy or who had a relapse after an initial response. A total of 663 patients were assigned to one of three groups: the T12PR48 group, which received telaprevir for 12 weeks and peginterferon plus ribavirin for a total of 48 weeks; the lead-in T12PR48 group, which received 4 weeks of peginterferon plus ribavirin followed by 12 weeks of telaprevir and peginterferon plus ribavirin for a total of 48 weeks; and the control group (PR48), which received peginterferon plus ribavirin for 48 weeks. The primary end point was the rate of sustained virologic response, which was defined as undetectable HCV RNA 24 weeks after the last planned dose of a study drug.

RESULTS

Rates of sustained virologic response were significantly higher in the two telaprevir groups than in the control group among patients who had a previous relapse (83% in the T12PR48 group, 88% in the lead-in T12PR48 group, and 24% in the PR48 group), a partial response (59%, 54%, and 15%, respectively), and no response (29%, 33%, and 5%, respectively) (P<0.001 for all comparisons). Grade 3 adverse events (mainly anemia, neutropenia, and leukopenia) were more frequent in the telaprevir groups than in the control group (37% vs. 22%).

CONCLUSIONS

Telaprevir combined with peginterferon plus ribavirin significantly improved rates of sustained virologic response in patients with previously treated HCV infection, regardless of whether there was a lead-in phase. (Funded by Tibotec and Vertex Pharmaceuticals; REALIZE ClinicalTrials.gov number, NCT00703118.).

Directly acting antivirals against hepatitis C virus

The approval of directly acting antivirals (DAA) for the treatment of chronic hepatitis C virus (HCV) infection will represent a major breakthrough for the 180 million persons infected worldwide. Paradoxically, hepatitis C is the only human chronic viral disease that can be cured, as all other pathogenic viruses infecting humans either display self-limited courses or establish non-eradicable persistent infections. Until now, treatment of chronic hepatitis C consisted of the combination of peginterferon-α plus ribavirin, which provided limited rates of cure and was associated with frequent side effects. Several DAA have been identified that inhibit the NS3 protease, the NS5B polymerase or the NS5A replication complex, and have entered the final steps of clinical development. These molecules, coupled with significant progress made in the recognition of more potent and safe interferon forms (e.g. interferon-λ) and host protein targets (e.g. alisporivir), are opening a new era in hepatitis C therapeutics. The expectations are so great that, to some extent, it is reminiscent of what happened in 1996 in the HIV field when the introduction of the first protease inhibitors as part of triple combinations revolutionized antiretroviral therapy. To maximize treatment success and reduce the likelihood of drug resistance selection, a proper individualization of hepatitis C therapy will be required, choosing the most convenient drugs and strategies according to distinct viral and host profiles. The complexity of HCV therapeutics has reached a point that presumably will lead to the birth of a new specialist, the HCV doctor.