Randomized trial of interferon beta-1a with or without ribavirin in Asian patients with chronic hepatitis C

Interferon β, an enhancer of the innate immune response against SARS-CoV-2 infection

COVID-19 exhibits a global health threat among the elderly and the population with underlying health conditions. During infection, the host's innate immune response acts as a frontline of defense by releasing cytokines such as type I interferon (IFN α and β) thereby initiating antiviral activity. However, this particular interferon response is interrupted by factors such as SARS-CoV-2 non-structural proteins, aging, diabetes, and germ-line errors eventually making the host more susceptible to illness. Therefore, enhancing the host's innate immune response by administering type I IFN could be an effective treatment against COVID-19. Here, we highlight the importance of innate immune response and the role of IFN β monotherapy against COVID-19.

The Removal of HBV in Plasma by Extracorporeal Immunoadsorption from Plasma: A Potential Therapy of Hepatitis B Patients

Objective

To establish a novel HBV specific immunoadsorbent for the removing of HBV particles.

Methods

The anti-HBsAg monoclonal antibody was immobilized on sepharose beads to produce a sepharose anti-HBs column. Then the immunoadsorbent was evaluated and characterized by scanning electron microscopy. In addition, time-dependent effects of the eradication capacity of anti-HBsAg functionalized sepharose beads against HBV were investigated.

Results

Proposed immunoadsorbents exhibited a favorable biocompatibility as well as specificity. With the optimized recycle time, the decontamination performance of HBV particles and quantity of HBsAg were assessed either by real-time quantitative PCR or ELISA, which showed that the immunoadsorbent could remove approximately 90% of the HBV and 90% of the HBsAg from human plasma samples.

Conclusions

All these results indicated that the novel immunoadsorbent could effectively remove HBV particles and likely serve as a novel therapy option or at least supplementary for the treatment regimen of HBV.

The effect of interferon-free regimens on health-related quality of life in East Asian patients with chronic hepatitis C

BACKGROUND

Interferon (IFN)-based regimens cause significant impairment of health-related quality of life (HRQL). Hepatitis C virus (HCV) cure with IFN-free regimens improves HRQL. The effect of these regimens on HRQL in East Asian HCV patients is unclear due to lack of published evidence.

AIM

To assess HRQL in East Asian HCV patients treated with an IFN-free regimen with sofosbuvir+ribavirin.

METHODS

Patients completed Short Form-36 (SF-36) before, during and after treatment.

RESULTS

686 subjects were included (China: 56.7%; S. Korea: 18.8%; Taiwan: 12.7%; genotype 2: 40.8%; genotype 1: 29.6%; genotype 3: 18.4%; genotype 6: 11.2%; cirrhosis: 13.4%; treatment-naïve: 66.5%). Patients received either pegylated-IFN, sofosbuvir, and ribavirin (IFN+SOF+RBV) for 12 weeks (n = 155, genotypes 1 and 6) or SOF+RBV for 12-24 weeks (n = 531, all genotypes). The SVR-12 rates were 95.5% and 96.0%; respectively (P = .76). Baseline HRQL scores were similar between treatment groups (all P > .05). By the end of treatment, the IFN-treated group experienced significant declines in most HRQL scores (on average, by up to -13.3 points on a 0-100 scale from the baseline level, P < .02) while subjects on SOF/RBV had milder impairments (up to -5.4 points). Achieving SVR-12 was associated with HRQL improvement regardless of regimen (up to +2.9 points, P < .05). The use of IFN-free treatment was a consistent independent predictor of higher HRQL scores during treatment (β: +2.1 to +10.7 points, P < .02).

CONCLUSIONS

East Asian HCV patients treated with an IFN-free regimen had better on-treatment HRQL scores. These data should inform policymakers about the comprehensive benefits of IFN-free regimens in East Asian patients with HCV.

Disease-modifying therapies and infectious risks in multiple sclerosis

Immunomodulatory and immunosuppressive treatments for multiple sclerosis (MS) are associated with an increased risk of infection, which makes treatment of this condition challenging in daily clinical practice. Use of the expanding range of available drugs to treat MS requires extensive knowledge of treatment-associated infections, risk-minimizing strategies and approaches to monitoring and treatment of such adverse events. An interdisciplinary approach to evaluate the infectious events associated with available MS treatments has become increasingly relevant. In addition, individual stratification of treatment-related infectious risks is necessary when choosing therapies for patients with MS, as well as during and after therapy. Determination of the individual risk of infection following serial administration of different immunotherapies is also crucial. Here, we review the modes of action of the available MS drugs, and relate this information to the current knowledge of drug-specific infectious risks and risk-minimizing strategies.

Patient-reported Outcomes in Asian Patients With Chronic Hepatitis C Treated With Ledipasvir and Sofosbuvir

Prevalence of chronic hepatitis C (CH-C) infection in patients of Asian ancestry ranges between 1% and 20%. Interferon (IFN)- and ribavirin (RBV)-containing regimens for CH-C have a negative impact on patient-reported outcomes (PROs) during treatment. The aim of this study was to assess the impact of IFN-free RBV-free sofosbuvir (SOF)-based regimens on PROs in CH-C patients of Asian ancestry. In this observational retrospective study, the PRO data from 12 multicenter multinational phase 3 clinical trials (2012-2015, conducted in Europe, North America, Australia, and New Zealand) of SOF-based regimens with and without IFN, ledipasvir (LDV), and/or RBV were used. At baseline, during treatment, and post-treatment, patients completed 4 validated PRO questionnaires (SF-36, CLDQ-HCV, FACIT-F, and WPAI:SHP). The resulting PROs in Asian patients were compared across the treatment regimens. Of 4485 of the trials' participants, 106 patients were of Asian ancestry (55.7% male, 69.8% treatment-naïve, 17.0% cirrhotic). In comparison with other patients, the Asian CH-C cohort was younger, had lower BMI, and lower rates of pre-treatment psychiatric comorbidities (anxiety, depression, sleep disorders) (all P < .05). At baseline, Asian patients also had lower SF-36 physical functioning scores (on average, by -5.6% on a normalized 0-100% PRO scale, P = .001). During treatment, Asian CH-C patients experienced a decline in their PRO scores while receiving IFN and/or RBV-containing regimens (up to -19.6%, P < .001). In contrast, patients receiving LDV/SOF experienced no PRO decrement and improvement of some PRO scores during treatment (+9.0% in general health of SF-36, P = .03). After achieving SVR-12, some of the PRO scores in Asian patients improved regardless of the regimen (up to +9.3%, P < .001). In multivariate analysis of Asian patients, the use of LDV/SOF was independently associated with higher PRO scores during and soon after the end of treatment (betas +15.0% to +29.3%, all P < .05). Other predictors of PRO impairment included depression, type 2 diabetes mellitus, and cirrhosis. The use of IFN- and RBV-free LDV/SOF regimens leads to PRO improvement in Asian patients with CH-C during treatment. Achieving SVR-12 results in improvement of PRO scores.

Natural interferon-beta treatment for patients with chronic hepatitis C in Japan

Chronic hepatitis C virus (HCV) infection can cause liver cirrhosis and hepatocellular carcinoma (HCC). Several studies have demonstrated that the eradication of HCV reduces the occurrence of HCC. In Japan, as many people live to an advanced age, HCV-infected patients are also getting older, and the age at HCC diagnosis has also increased. Although older HCV-infected patients have a risk of developing HCC, the treatment response to peginterferon-alpha plus ribavirin therapy is relatively poor in these patients because of drop-out or discontinuation of this treatment due to adverse events. It is established that the mechanism of action between interferon-alpha and interferon-beta is slightly different. Short-term natural interferon-beta monotherapy is effective for patients with acute hepatitis C and patients infected with HCV genotype 2 and low viral loads. Natural interferon-beta plus ribavirin for 48 wk or for 24 wk are also effective for some patients with HCV genotype 1 or HCV genotype 2. Natural interferon-beta plus ribavirin has been used for certain “difficult-to-treat” HCV-infected patients. In the era of direct-acting anti-virals, natural interferon-beta plus ribavirin may be one of the therapeutic options for special groups of HCV-infected patients. In the near future, signal transduction pathways of interferon-beta will inform further directions.

Serotonin and its implication in the side-effects of interferon-based treatment of patients with chronic viral hepatitis: Pharmacological interventions

Depression is a frequent side-effect of interferon-based treatment of patients with chronic viral hepatitis, that may lead to reduction or discontinuation of treatment. Clinical trials data showed the importance of therapy of psychiatric disorders for a successful antiviral treatment. Emerging evidence suggests that interferon may cause depression affecting serotonin synthesis via increased activity of indoleamine 2,3-dioxygenase. Serotonin reuptake inhibitors significantly improve mood disorders, but the use of these drugs requires caution because some studies reported the emergence of mania in patients treated for depression during antiviral therapy. Therefore, this review will examine and discuss the putative role of serotonin and its metabolism in the development of depression during antiviral therapy, focusing on pharmacological interventions to reduce side-effects.

Site-specific PEGylation enhances the pharmacokinetic properties and antitumor activity of interferon beta-1b

Interferon beta (IFN-β) is widely used to ameliorate disease progression in patients with Multiple Sclerosis. IFN-β has a short half-life in humans, necessitating frequent administration for optimum effectiveness. Covalent modification of IFN-β with polyethylene glycol (PEG) improves the pharmacokinetic properties of the protein, but can adversely affect the protein's in vitro bioactivity. Random modification of lysine residues in IFN-β with amine-reactive PEGs decreased the in vitro bioactivity of the protein 50-fold, presumably due to modification of lysine residues near critical receptor binding sites. PEGylated IFN-β proteins that retained high in vitro bioactivity could be obtained by selective modification of the N-terminus of the protein with PEG. Here we use site-specific PEGylation technology (targeted attachment of a cysteine-reactive-PEG to an engineered cysteine residue in IFN-β) to identify several additional amino acid positions where PEG can be attached to IFN-β without appreciable loss of in vitro bioactivity. Unexpectedly, we found that most of the PEG-IFN-β analogs showed 11- to 78-fold improved in vitro bioactivities relative to their unPEGylated parent proteins and to IFN-β-1b. In vivo studies showed that a lead PEG-IFN-β protein had improved pharmacokinetic properties compared to IFN-β and was significantly more effective than IFN-β at inhibiting growth of a human tumor xenograft in athymic mice.

Interferon-free regimens: the near future, the likely and the not so likely

Remarkable progress has been achieved in the treatment of chronic hepatitis C virus (HCV) since interferon was first used to treat this pathogen more than 20 years ago. This article reviews the mechanisms through which interferon is believed to suppress HCV and lead to SVR. These observations are used to speculate as to whether an all-oral antiviral cocktail could "cure" HCV in the near future.

Interferon-β and interferon-λ signaling is not affected by interferon-induced refractoriness to interferon-α in vivo

Therapy of chronic hepatitis C with pegylated interferon α (pegIFN-α) and ribavirin achieves sustained virological responses in approximately half of the patients. Nonresponse to treatment is associated with constitutively increased expression of IFN-stimulated genes in the liver already before therapy. This activation of the endogenous IFN system could prevent cells from responding to therapeutically injected (peg)IFN-α, because prolonged stimulation of cells with IFN-α induces desensitization of the IFN signal transduction pathway. Whether all types of IFNs induce refractoriness in the liver is presently unknown. We therefore treated mice with multiple injections and different combinations of IFN-α, IFN-β, IFN-γ, and IFN-λ. Pretreatment of mice with IFN-α, IFN-β, and IFN-λ induced a strong expression of the negative regulator ubiquitin-specific peptidase 18 in the liver and gut. As a result, IFN-α signaling was significantly reduced when mice where reinjected 16 hours after the first injection. Surprisingly, both IFN-β and IFN-λ could activate the Janus kinase-signal transducer and activator of transcription (STAT) pathway and the expression of IFN-stimulated genes despite high levels of ubiquitin-specific peptidase 18. IFN-λ treatment of human liver biopsies ex vivo resulted in strong and maintained phosphorylation of STAT1, whereas IFN-α-induced STAT1 activation was transient.

CONCLUSION

Contrary to the action of IFN-α, IFN-β, and IFN-λ signaling in the liver does not become refractory during repeated stimulation of the IFN signal transduction pathway. The sustained efficacy of IFN-β and IFN-λ could be an important advantage for the treatment patients who are nonresponders to pegIFN-α, through a preactivated endogenous IFN system.

Emerging therapies for hepatitis C virus

IMPORTANCE OF THE FIELD

Currently, 170 million people worldwide are affected by the HCV. Chronic HCV infection is amongst the leading causes of chronic liver disease and its complications such as cirrhosis and hepatocellular carcinoma, making it the most common reason for liver transplantation. The current standard of treatment for HCV is pegylated IFN-α plus ribavirin. This treatment, when administered for the standard duration, allows sustained virological response (SVR) in ∼ 50% of patients infected with HCV and about 40% for HCV genotype 1, the most prevalent form of HCV in the US. SVR rates for populations with co-morbidities (patients with chronic renal disease) and certain ethnic backgrounds (African Americans and Hispanics) are lower. Given the high prevalence and relatively low cure rates of current antiviral therapy, the burden of HCV is enormous.

AREAS COVERED IN THIS REVIEW

Faced with this urgent and growing medical need, research into novel therapeutic compounds for the treatment of HCV is a rapidly growing industry. Several novel compounds are in advanced stages of clinical development, such as HCV protease inhibitors (particularly those against NS3-4A protease), HCV polymerase inhibitors (including both nucleoside and non-nucleoside analogs) and cyclophilin inhibitors.

WHAT THE READER WILL GAIN

HCV treatment has seen many advances in the last decade and the discovery process has been fraught with both successes and disappointments. Through a process of rigorous research, the current late stage novel HCV therapeutics seem to have overcome some of the obstacles met by their early predecessors and offer the promise of meeting the shortfalls of the current standard of treatment.

TAKE HOME MESSAGE

Data from clinical trials are encouraging and suggest that combination therapies of these novel agents may have the potential to shorten treatment duration and increase viral clearance when used in conjunction with pegylated IFN-α and ribavirin.

Serum 90K/Mac-2 binding protein (Mac-2BP) as a response predictor to peginterferon and ribavirin combined treatment in HCV chronic patients

90K/Mac-2BP glycoprotein is involved in the immune defense against a variety of neoplasms and viral infections, modulating the activity of several effectors such as natural killer cells. Quite interestingly, 90K/Mac-2BP is associated to a poor response to interferon (IFN) alpha in hepatitis C virus (HCV) infected patients. Here, in 70 consecutive HCV chronic patients, we have evaluated 90K basal levels as a response predictor to combined therapy with Peginterferon and Ribavirin. We have found higher 90K levels in genotype 1/4 than in genotype 2/3 (p = 0.006) and in 62.5% of non-responders than in 20% of responders (p < 0.001). Genotype 1/4, higher 90K and gamma glutamyl transferase (gammaGT) levels resulted independently associated to a status of refractoriness to therapy. Consequently, evaluation of 90K serum levels seems to be a promising useful marker of response to combined therapy in HCV disease.

Progress towards improving antiviral therapy for hepatitis C with hepatitis C virus polymerase inhibitors. Part I: Nucleoside analogues

BACKGROUND

With an increasing worldwide burden of liver failure and liver cancer from chronic hepatitis C virus (HCV) infection, discovery and development efforts for new antiviral medicines for HCV are expanding rapidly. Two HCV protease inhibitors (PIs), telaprevir (VX950) and boceprevir (SCH503034), are now furthest along in clinical development, with Phase II data suggesting a potential treatment advance with triple combination regimens comprising a protease inhibitor, pegylated interferon and ribavirin. However, the current data suggest that such regimens will fail to produce sustained virologic responses in > or = 30 - 40% of patients, and tolerance of interferon/ribavirin treatment regimens is often problematic; hence, there is a need for continued development of new anti-HCV agents to further optimize treatment efficacy and safety. The HCV polymerase (HCV Pol) is an attractive target for antiviral therapy because the gene sequences encoding HCV Pol are relatively conserved across the six main HCV genotypes and the emergence of viral resistance is expected to be relatively slow for pharmaceutical agents, such as nucleoside analogues, that are targeted to the active (catalytic) site of HCV Pol.

METHODS

This review (Part I) of HCV Pol inhibitors focuses on the scientific rationale and recent development progress for nucleoside-type HCV Pol inhibitors; a subsequent review (Part II) will assess progress with non-nucleosidic HCV Pol inhibitors.

RESULTS/CONCLUSIONS

Early clinical data for several nucleosides targeted to HCV Pol indicate marked antiviral effects and a likelihood of relatively slow HCV resistance, consistent with the profile of nucleosidic inhibitors of HIV and hepatitis B virus infection and supporting potentially important roles for nucleoside agents in optimizing combination therapies for HCV infection. Optimally effective future anti-HCV therapies are likely to be based on multi-class treatment regimens combining polymerase and PIs, together with pegylated interferon and ribavirin or pharmaceutical agents from other mechanistic classes.

Novel interferons for treatment of hepatitis C virus

The current standard of care for treatment of hepatitis C is pegylated interferon and ribavirin. Despite the large number of new oral agents under development, interferon will likely remain the backbone of future therapy. Interferon has unique antiviral and immunomodulatory properties, which have been critical in limiting resistance to protease inhibitors and improving efficacy. Hence, optimizing pharmacokinetics and promoting adherence to interferon dosing regimens will become even more critical as new regimens enter the clinical arena. This review highlights novel interferons under development that may offer therapeutic advantages over the formulations currently available.

Recombinant interferon-Beta-1alpha plus ribavirin for the treatment of chronic HCV infection: a prospective, randomized, comparative pilot study

BACKGROUND/AIMS

Interferon beta (IFN-beta) has been shown to have antiviral activity, and thus could be useful in treating viral infections. Therefore, we compared the efficacy and safety of recombinant IFN-beta (IFN-beta-1a) plus oral ribavirin versus interferon alpha (IFN-alpha) plus ribavirin therapy for the treatment of chronic hepatitis C (HCV).

METHODS

Twenty treatment-naïve patients were randomized into two equal-sized treatment groups. Both IFN-beta-1a (44 microg) and IFN-alpha (3 MIU) were given subcutaneously three times a week, while ribavirin was given orally at 1,000-1,200 mg/day. Patients were treated for 24 weeks and followed for an additional 24 weeks.

RESULTS

After 24 weeks of treatment, six (60%) and four patients (40%) in the IFN-beta-1a group and IFN-alpha groups, respectively, achieved viral clearance. The sustained virological response (SVR) at the end of the observation period was similar in both groups (40%). However, the baseline viral load was significantly higher (p=0.034) in the IFN-beta-1a group than in the IFN-alpha group, and there were more HCV genotype 1 patients in the IFN-beta-1a group (eight versus seven). The IFN-beta-1a group was associated with similar adverse events in terms of frequency and severity.

CONCLUSIONS

The SVR rate and safety profile were similar for the combination of IFN-beta-1a and ribavirin and that of IFN-alpha and ribavirin.

Treatment of chronic hepatitis C in Asia: when East meets West

The issue of best treatment for chronic hepatitis C virus (HCV) infection is in constant flux, not only in Western countries but also in Asia. Currently, pegylated-interferon plus ribavirin is the standard of care. Studies from Asia provide evidence to support the same broad treatment strategies for Asian patients as recommended in Western countries. Nevertheless, there is increasing evidence that Asians have a higher likelihood of achieving a sustained virological response (SVR) than their Caucasians counterparts when treated with the corresponding regimen. With the recommended 'standard dose and duration treatment regimens', SVR is achieved in Asia for around 70% of HCV genotype 1 (HCV-1) infected cases, approximately 90% of HCV-2/3, approximately 65% of HCV-4, and approximately 80% of HCV-6 patients. Difference of body weight in race might contribute the superior response in Asian patients. HCV genotype distribution in Asia also differs from North-America/Europe. HCV-6 and its variants, previously mistyped as HCV-1, needs accurate genotyping. Increasing data support the proposal that HCV genotype, baseline viral load and on-treatment virological response provide information for decision-making so that treatment can be individualized. Beyond the older recommendations, an abbreviated 24-week regimen could be suggested for HCV-1/4 patients with baseline viral loads < 400 000 IU/mL and a rapid virological response (RVR, HCV RNA undetectable at week 4), and an abbreviated 12-16 weeks of pegylated-interferon with weight-based doses of ribavirin could be suggested for HCV-2/3 patients with a RVR. Such tailored treatment regimens can reduce the costs of treatment and incidence of adverse events without compromising efficacy. Hepatitis C virus (HCV) infection is one of the most important causes of cirrhosis worldwide, and particularly in some countries of Asia (notably Japan) where it is now more prevalent than chronic hepatitis B virus infection. Hepatitis C virus infection can also lead to hepatocellular carcinoma (HCC). It is estimated that there are more than 170 million people chronically infected with HCV, and 3 to 4 million persons are newly infected each year. The risk for developing cirrhosis 20 years after initial HCV infection among those chronically infected varies between studies, but is estimated at around 10%-15% for men and 1-5% for women. Once cirrhosis is established, the rate of developing HCC is at 1%-4% per year. Approximately 280 000 deaths per year are related to HCV infection. Hepatitis C virus-related end-stage liver disease and HCC have become the leading cause for liver transplantation worldwide. In the Asia-Pacific area, the estimated prevalence of antibodies to HCV (anti-HCV) range from 0.3% in New Zealand to 5.6% in Thailand. In Japan, Middle East, Vietnam and Taiwan, several HCV hyper-endemic areas have been reported with an anti-HCV prevalence rate of 12% to as high as 58%. In addition to the well-known endemic status of HBV infection in most countries of the Asia-Pacific region, HCV infection presents another critical scenario of public health issue in this region, as outlined in Guidelines by the Asia-Pacific Association for Study of the Liver (APASL). Given the lack of an effective vaccine, optimal treatment of chronic HCV infection is now perceived as a 'must' in terms of public health strategies, as well as of the clinical setting for individual patients.

Preclinical characteristics of the hepatitis C virus NS3/4A protease inhibitor ITMN-191 (R7227)

Future treatments for chronic hepatitis C virus (HCV) infection are likely to include agents that target viral components directly. Here, the preclinical characteristics of ITMN-191, a peptidomimetic inhibitor of the NS3/4A protease of HCV, are described. ITMN-191 inhibited a reference genotype 1 NS3/4A protein in a time-dependent fashion, a hallmark of an inhibitor with a two-step binding mechanism and a low dissociation rate. Under preequilibrium conditions, 290 pM ITMN-191 half-maximally inhibited the reference NS3/4A protease, but a 35,000-fold-higher concentration did not appreciably inhibit a panel of 79 proteases, ion channels, transporters, and cell surface receptors. Subnanomolar biochemical potency was maintained against NS3/4A derived from HCV genotypes 4, 5, and 6, while single-digit nanomolar potency was observed against NS3/4A from genotypes 2b and 3a. Dilution of a preformed enzyme inhibitor complex indicated ITMN-191 remained bound to and inhibited NS3/4A for more than 5 h after its initial association. In cell-based potency assays, half-maximal reduction of genotype 1b HCV replicon RNA was afforded by 1.8 nM; 45 nM eliminated the HCV replicon from cells. Peginterferon alfa-2a displayed a significant degree of antiviral synergy with ITMN-191 and reduced the concentration of ITMN-191 required for HCV replicon elimination. A 30-mg/kg of body weight oral dose administered to rats or monkeys yielded liver concentrations 12 h after dosing that exceeded the ITMN-191 concentration required to eliminate replicon RNA from cells. These preclinical characteristics compare favorably to those of other inhibitors of NS3/4A in clinical development and therefore support the clinical investigation of ITMN-191 for the treatment of chronic hepatitis C.

Dynamic Evolution of Therapy for Chronic Hepatitis C: How will Novel Agents be Incorporated into the Standard of Care?

There is a need for improved treatment strategies and new therapeutic agents to increase cure rates in chronic hepatitis C virus (HCV) infection. Ongoing trials are aimed at optimizing sustained virological response rates with pegylated interferon (PEG-IFN) plus ribavirin. For a new agent to supplant the standard of care it must augment the strengths or compensate for the weaknesses of PEG-IFN plus ribavirin. To improve cure rates on its own, a new agent must not only suppress replication of the virus, but also clear infected hepatocytes. It is now clear that new anti-HCV agents will be used, at least initially, against a backbone of PEG-IFN plus ribavirin. A broad spectrum of agents is under investigation and it is hoped that these drugs will ultimately increase cure rates, reduce the required duration of therapy, improve tolerability and possibly simplify therapy. Reductions in serum HCV RNA ranging from 2 to 5 log10 IU/ml have been obtained in human trials with NS3/4A protease inhibitors and polymerase inhibitors. A minimum of additive reductions in serum HCV RNA levels have been observed when agents in these classes have been administered with PEG-IFN plus ribavirin in treatment-naive patients. Preliminary results in non-responders to IFN are less promising. Combinations of small molecules will be needed in order to produce sustained suppression of HCV replication in the absence of the standard of care, and such large clinical trials are several years away. The treatment paradigm for chronic hepatitis C continues to evolve and will eventually incorporate new drugs as they are approved.

The emerging field of HCV drug resistance

BACKGROUND

With 170 million people infected worldwide and an inadequate current standard of care, hepatitis C virus (HCV) infection represents a major unmet medical need. Multiple companies are working on the discovery and development of specific HCV antiviral drugs, including inhibitors of HCV polymerase, protease and NS5A. Because of the error-prone nature of viral RNA replication, resistance mutants will develop that could present a potentially significant challenge to developing antiviral treatment regimens.

OBJECTIVE

Here, we review the major drug classes currently in preclinical and clinical development and the resistance mutations specific for each class that have been identified from cell culture and/or in vivo studies.

METHODS

We have analyzed currently available scientific literature to create a comprehensive review of the current state of the art in the field of HCV resistance to specific antiviral agents, in vitro and in vivo.

RESULTS/CONCLUSION

Most specific HCV inhibitors described in the literature can select resistant viral variants in cell culture and in the clinic. Interplay of a mutant's fitness and its level of resistance will determine its clinical importance. Combinations of non-cross-resistant classes of drugs will be key to successful antiviral therapy. The number of drugs in a combination as well as the optimal duration of antiviral treatment, are important issues that need to be addressed in future studies.

[New data and recommendations of antiviral therapy of chronic hepatitis B and C]

According to the new German guidelines therapy of chronic hepatitis B is recommended when HBV-DNA is >10.000 copies/ml and when GPT is >twice the ULN or biopsy shows inflammation/fibrosis. When patients are not suitable for interferon therapy, mono-therapy with adefovir, entecavir, telbivudine of lamivudine may be initiated provided that HBV-DNA is <1 Mio. copies/ml and cirrhosis is absent. When viral load is high, entecavir should be preferred. HBV-DNA need to be checked for early detection of non-response or resistance. When resistance is present, combination therapy is recommended.New studies warrant individualization of previous recommendation for therapy of hepatitis C because one can now early evaluate how successful and long the therapy shall be. When viral load is low and HCV-RNA becomes negative after 4 weeks, therapy may be shortened to 24 weeks. Without such rapid response HCV-RNA needs to be checked after 12 and 24 weeks: when HCV-RNA becomes negative only after 24 weeks, a prolongation of therapy might be advisable.

Natural human interferon beta plus ribavirin combination therapy in Japanese patients infected with hepatitis C virus and a high viral load

OBJECTIVE

The aim of this pilot study was to determine the safety and efficacy of natural human interferon beta (nIFNbeta) plus ribavirin (RBV) in patients with chronic hepatitis C who did not respond to pegylated interferon alpha (PEG-IFN), with special emphasis on the incidence of mental disorders or refusal for fear of adverse effects.

METHODS

We studied 19 patients with HCV genotype 1b, 2a or 2b and a high viral load, including 8 patients with mental disorders. They were treated with nIFNbeta-RBV. Eleven patients with HCV genotype 1b of these patients were treated with nIFNbeta-RBV for 48 weeks (group A), and compared with 22 matched controls treated with PEG-IFN plus RBV for 48 weeks (group B). The other 8 patients with HCV genotype 2 were treated with nIFNbeta-RBV for 24 weeks.

RESULTS

Six of 8 patients with mental disorders and 9 of 11 patients without mental disorders completed nIFNbeta-RBV therapy; 1 patient with mental disorder dropped out due to exacerbation of depression, and 3 patients suspended the therapy due to insufficient response. The sustained virological response (SVR) was 27% (3/11) in group A and 41% (9/22) in group B (p = 0.70). During treatment, platelet count increased in group A but not in group B. SVR was 88% (7/8) in patients of genotype 2 and high viral load treated with nIFNbeta plus RBV.

CONCLUSION

nIFNbeta-RBV therapy offers sufficient safety and efficacy for patients with mental disorders, and thus could represent an excellent second-line therapy for subpopulations that are not suitable for PEG-IFN-RBV.