Ribavirin monotherapy in patients with chronic hepatitis C: a retrospective study of 95 patients

A randomized controlled trial of SOF/VEL/VOX with or without ribavirin for retreatment of chronic hepatitis C

BACKGROUND & AIMS

The combination of sofosbuvir, velpatasvir and voxilaprevir (SOF/VEL/VOX) is recommended retreatment for patients with hepatitis C virus (HCV) infection who failed previous direct-acting antiviral (DAA) treatment. However, whether ribavirin further increases the therapeutic efficacy of SOF/VEL/VOX retreatment remains unclear. We aimed to test this hypothesis by a randomized controlled trial.

METHODS

We randomly assigned 315 patients with DAA treatment failure from 5 Egyptian sites into two groups. Group A (n=158) received SOF/VEL/VOX for 12 weeks, and group B (n=157) received SOF/VEL/VOX + weight-based ribavirin for 12 weeks. Therapeutic efficacy was defined as SVR12 (undetectable HCV RNA 12 weeks after treatment completion). Safety and tolerability were evaluated by monitoring treatment-related adverse events (AEs) and laboratory abnormalities.

RESULTS

Seventeen patients in each group were lost to follow-up. SVR12 rates by intention-to-treat (ITT) were 87.3% (138/158), and by per-protocol analysis, 97.8% (138/141) in group A; and 87.9% (138/157) and 98.5% (138/140) in group B (p=NS for ITT and PP). Males comprised 53.9% of group A, and 57.1% in group B (p=0.58), with mean ages of 51.8 and 47.3 years in group A and B, respectively. Both regimens were well-tolerated, with no deaths and only one serious AE (anemia) in group B requiring ribavirin discontinuation. Fifty-five patients in group A vs. 77 in group B experienced any adverse events (p=0.002).

CONCLUSION

This randomized controlled trial showed equal, high efficacy of both regiments in retreating previous DAA failures, although ribavirin was associated with more adverse events. Therefore SOF/VEL/VOX monotherapy should be the preferred retreatment strategy.

IMPACT AND IMPLICATIONS

HCV treatment guidelines recommend retreating DAA treatment failures with the combination of sofosbuvir, velpatasvir and voxilaprevir (SOF/VEL/VOX) for 12 weeks. However, whether ribavirin exerts an additional/synergistic effect remains unclear. The present study confirmed that SOF/VEL/VOX without ribavirin is the best regimen for retreating DAA treatment failures, and thus will help clinicians caring for patients who are not cured with a first course of DAA therapy. CLINCIALTRIALS.

GOV NUMBER

NCT04695769.

Serious Adverse Events with Sofosbuvir Combined with Interferon and Ribavirin: Real-Life Egyptian Experience

Viral hepatitis is a serious problem worldwide that was under-recognized till recently. The prevalence of chronic hepatitis C virus (HCV) is estimated to be 180 million people worldwide. Treatment of chronic HCV using combined pegylated interferon and ribavirin (PEG/RIBA) has long been the standard of care with modest response. In our study, we will report the real-life experience of serious adverse events (SAEs) that were reported by the National Committee for Control of Viral Hepatitis (NCCVH, Cairo, Egypt) program while treating chronic HCV using the triple therapy, sofosbuvir combined with pegylated interferon and ribavirin (PEG/RIBA/SOF), which led to premature discontinuation of treatment. This retrospective analysis included a total of 6,989 chronic HCV patients who were treated by the NCCVH. They received the triple antiviral therapy in 26 treatment centers in Egypt using PEG/RIBA/SOF for 12 weeks. Among 6,989 patients who were treated in 26 treatment centers related to NCCVH, 406 cases (5.9%) reported SAEs and prematurely stopped their treatment. Triple therapy PEG/RIBA/SOF was an important intermediate milestone between interferon-based therapy and the interferon-free all-oral direct acting antiviral agents (DAAs). Results of this study were the leading cause of discontinuation of interferon-based therapy and introduction of interferon-free all-oral treatment protocols, incorporating DAAs from different classes as soon as they gain approval.

QiHong Prevents Death in Coxsackievirus B3–Induced Murine Myocarditis Through Inhibition of Virus Attachment and Penetration

Viral myocarditis affects about 5% to 20% of the population. So far, there are not many effective antiviral treatments available. QiHong, the combination of the extracts from Astragali (Huangqi), Rhadiola rosea (Hongjingtian), and Sophora flavescens (Kushen), was developed based on laboratory research. The aim of this study was to investigate the effect and mechanism of QiHong on coxsackievirus B3 (CVB3)–induced myocarditis. The antiviral activity of QiHong in vitro was evaluated on HeLa and Vero cells infected by CVB3. Ribavirin was chosen as positive control. Our results showed that QiHong possessed potent antiviral effects on CVB3 by sodium 3′-[1-(phenylamino-carbonyl)-3, 4-tetrazolium]-bis (4-methoxy-6-nitro) benzene sulfonic acid and plaque-forming assay (50% inhibitory concentrations [IC50] were 7.16 ± 0.8 μg/ml and 2.63 ± 0.5 μg/ml, respectively). The 50% cytotoxicity concentration (CC50) was 16-fold higher in QiHong-treated cells than in ribavirin-treated cells. Time course studies demonstrated that the antiviral effect of QiHong was mainly found during 0–4 hrs of infection, and it blocked the attachment and penetration of CVB3 into cells. In vivo 4-week-old male Balb/C mice were used and inoculated intraperitoneally with CVB3 suspension or normal saline. At 48 hrs after inoculation, the infected mice were gavaged with QiHong or ribavirin. On Day 6, myocardial virus titers were significantly lower in the QiHong-treated group than in the viral-infected groups. On Day 14, QiHong significantly ameliorated CVB3-induced myocardium necrosis; on Day 28, QiHong treatment increased survival rate 4-fold compared with CVB3-infected controls (64% vs. 16%; P < 0.05). The results showed that QiHong is a very promising potent antiviral agent with a highly significant favorable effect on survival and pathologic changes in CVB3-induced myocarditis with less toxicity than ribavirin. The antiviral activity of QiHong is at least partially due to an inhibitory effect on virus attachment and penetration.

Ribavirin restores IFNα responsiveness in HCV-infected livers by epigenetic remodelling at interferon stimulated genes

OBJECTIVES

Caveats in the understanding of ribavirin (RBV) mechanisms of action has somehow prevented the development of better analogues able to further improve its therapeutic contribution in interferon (IFN)-based and direct antiviral agent-based regimens for chronic HCV or other indications. Here, we describe a new mechanism by which RBV modulates IFN-stimulated genes (ISGs) and contributes to restore hepatic immune responsiveness.

DESIGN

RBV effect on ISG expression was monitored in vitro and in vivo, that is, in non-transformed hepatocytes and in the liver of RBV mono-treated patients, respectively. Modulation of histone modifications and recruitment of histone-modifying enzymes at target promoters was analysed by chromatin immunoprecipitation in RBV-treated primary human hepatocytes and in patients' liver biopsies.

RESULTS

RBV decreases the mRNA levels of several abnormally preactivated ISGs in patients with HCV, who are non-responders to IFN therapy. RBV increases G9a histone methyltransferase recruitment and histone-H3 lysine-9 dimethylation/trimethylation at selected ISG promoters in vitro and in vivo. G9a pharmacological blockade abolishes RBV-induced ISG downregulation and severely impairs RBV ability to potentiate IFN antiviral action and induction of ISGs following HCV infection of primary human hepatocytes.

CONCLUSIONS

RBV-induced epigenetic changes, leading to decreased ISG expression, restore an IFN-responsive hepatic environment in patients with HCV, which may also prove useful in IFN-free regimens.

Ribavirin at the Era of Novel Direct Antiviral Agents for the Treatment of Hepatitis C Virus Infection: Relevance of Pharmacological Monitoring

Ribavirin is often used for the treatment of hepatitis C virus (HCV) infection. Although its mechanisms of action remain to be clearly elucidated, ribavirin plays a beneficial role for achieving virological response and decreasing the rate of virological relapse after treatment cessation. However, ribavirin may induce side effects leading to early treatment discontinuation. Among them, hemolytic anemia is the most frequent and results from intraerythrocyte accumulation. Pharmacological studies have shown that early ribavirin exposure assessed by the area under the curve (AUC) at day 0 and ribavirin trough concentration during the first three months of therapy were correlated with sustained virological response (SVR). These studies highlighted the relevance of ribavirin pharmacologic monitoring and early dose adaptation during therapy. Although the role of ribavirin within new direct acting antiviral (DAA) combinations will probably decrease in the future, its potential benefit in difficult-to-treat patients such as patients with severe hepatopathy or patients who failed triple therapy including patients with multiresistance will need to be further investigated.

Cleavage of the T cell protein tyrosine phosphatase by the hepatitis C virus nonstructural 3/4A protease induces a Th1 to Th2 shift reversible by ribavirin therapy

Ribavirin has proven to be a key component of hepatitis C therapies both involving IFNs and new direct-acting antivirals. The hepatitis C virus-mediated interference with intrahepatic immunity by cleavage of mitochondrial antiviral signaling protein (MAVS) and T cell protein tyrosine phosphatase (TCPTP) suggests an avenue for compounds that may counteract these effects. We therefore studied the effects of ribavirin, with or without inhibition of the nonstructural (NS)3/4A protease, on intrahepatic immunity. The intrahepatic immunity of wild-type and NS3/4A-transgenic mice was determined by Western blot, ELISA, flow cytometry, and survival analysis. Various MAVS or TCPTP constructs were injected hydrodynamically to study their relevance. Ribavirin pretreatment was performed in mice expressing a functional or inhibited NS3/4A protease to analyze its effect on NS3/4A-mediated changes. Intrahepatic NS3/4A expression made mice resistant to TNF-α-induced liver damage and caused an alteration of the intrahepatic cytokine (IFN-γ and IL-10) and chemokine (CCL3, CCL17, CCL22, CXCL9, and CXCL11) profiles toward an anti-inflammatory state. Consistent with this, the number of intrahepatic Th1 cells and IFN-γ(+) T cells in NS3/4A-transgenic mice decreased, whereas the amount of Th2 cells increased. These effects could be reversed by injection of uncleavable TCPTP but not uncleavable MAVS and were absent in a mouse expressing a nonfunctional NS3/4A protease. Importantly, the NS3/4A-mediated effects were reversed by ribavirin treatment. Thus, cleavage of TCPTP by NS3/4A induces a shift of the intrahepatic immune response toward a nonantiviral Th2-dominated immunity. These effects are reversed by ribavirin, supporting that ribavirin complements the effects of direct-acting antivirals as an immunomodulatory compound.

Review article: management of chronic hepatitis C in patients with contraindications to anti-viral therapy

BACKGROUND

There are patients with chronic hepatitis C who are not eligible for the current interferon-based therapies or refuse to be treated due to secondary effects.

AIM

To provide information on alternative treatments for the management of these patients.

METHODS

A PubMed search was performed to identify relevant literature. Search terms included hepatitis C virus, anti-inflammatory treatment, antioxidant, natural products and alternative treatment, alone or in combination. Additional publications were identified using the references cited by primary and review articles.

RESULTS

Several approaches, such as iron depletion (phlebotomy), treatment with ursodeoxycholic acid or glycyrrhizin, have anti-inflammatory and/or anti-fibrotic effects. Life interventions like weight loss, exercise and coffee consumption are associated with a biochemical improvement. Other alternatives (ribavirin monotherapy, amantadine, silibinin, vitamin supplementation, etc.) do not have any beneficial effect or need to be tested in larger clinical studies.

CONCLUSION

There are therapeutic strategies and lifestyle interventions that can be used to improve liver damage in patients with chronic hepatitis C who cannot receive or refuse interferon-based treatments.

Containing "The Great Houdini" of viruses: combining direct acting antivirals with the host immune response for the treatment of chronic hepatitis C

Presently the development of new therapies for hepatitis C virus (HCV) is rapidly moving forward. Almost every week new data appear on how direct acting antivirals (DAAs) succeed or fail in clinical trials. Despite the potency of many of the DAA combinations, the effect exerted by ribavirin (RBV) is still needed for an effective therapy in many new DAA combinations. Due to the strong antiviral effect of DAAs, it is likely that a major complementary therapeutic effect exerted by RBV is immune modulation resulting in an increased barrier to development of resistance. For HCV genotype 1a infections elimination of pegylated interferon, is not possible in many DAA combinations without jeopardizing the results. The host immune response is thus likely to play a key role even during DAA-based therapies. Hence, T cells may recognize and eliminate viral variants with resistance to the DAAs. We herein show several examples where this may be the case, supporting the rationale of including the host response also in the new therapeutic regimens. This review will describe the potential benefits of combining various DAAs with means to activate the specific immune response against HCV.

Assessment of the treatment of chronic hepatitis C in the state of Mato Grosso, central Brazil

In Brazil, the treatment of hepatitis C virus (HCV) infection is funded by the national public health system (SUS). To evaluate treatment results in the state of Mato Grosso, central Brazil, we have consulted the files of the office of the State Department of Health responsible for supplying such medications. We obtained information on 232 treatments of 201 patients who underwent treatment in or prior to 2008. The study was conducted by reviewing medical records, making telephone calls and interviewing the assistant physicians. Thirty-nine patients (19.4%) had cirrhosis and HCV genotype 1 predominated (64.3%). Excluding patients with comorbidities or treatment without ribavirin we analysed 175 treatments (sustained virologic response occurred in 32.6% of cases). Twenty-six of these 175 were retreatments and the sustained virological response (SVR) rate among them was 30.8%; the SVR rate was 32.9% among those receiving treatment for the first time. The SVR rate of genotype 1 patients was 27.8%, whereas it was 37.5% in non-1 genotype patients. The adjusted multivariate analysis showed association of SVR with the absence of cirrhosis [odds ratio (OR): 7.7; confidence interval (CI) 95%: 2.5, 33.3], the use of pegylated interferon (OR: 5.8; CI 95%: 1.5, 21.4), non-1 genotype (OR: 5.3; CI 95%: 1.7, 16.7) and uninterrupted treatment (OR: 9.0; CI 95%: 3.3, 45.4). The SVR rates were similar to those found in other Brazilian studies about HCV, but lower than those found in national and international clinical trials. These data suggest that the treatments of chronic hepatitis C that are made available by SUS does not, under normal conditions, work as well as the original controlled studies indicated.

VIRAL DYNAMICS IN A DISTRIBUTED TIME DELAYED HCV PATHOGENESIS MODEL

In this paper, we investigate global dynamics for a distributed time delayed HCV infection model. Our model admits two possible equilibria, an uninfected equilibrium and infected equilibrium depending on the basic reproduction number. By employing the method of Lyapunov functional, we prove that the uninfected equilibrium is global asymptotically stable if the basic reproduction number is less than one, it is unstable and the infected equilibrium is global asymptotically stable if the basic reproduction number is larger than one. The simulations results are in good accordance with our analytic results.

Randomised clinical trial: pre-dosing with taribavirin before starting pegylated interferon vs. standard combination regimen in treatment-naïve patients with chronic hepatitis C genotype 1

BACKGROUND

Combination therapy with the ribavirin (RBV) prodrug taribavirin (TBV) and pegylated interferon (PIFN) has produced lower rates of anaemia than with RBV and PIFN. Studies have demonstrated that the sharpest decline in viral load during TBV therapy occurs at Weeks 4 through 6, when TBV reaches steady-state blood levels.

AIM

The current proof-of-concept study was conducted to examine whether first-order viral kinetics could be influenced by pre-dosing TBV to steady state before introducing PIFN.

METHODS

Therapy-naïve patients with chronic hepatitis C virus (HCV) genotype 1 (G1) were randomised to receive (i) TBV 600 mg BID monotherapy for 4 weeks followed by combination therapy with PIFN [pre-dosing arm (n = 23)] or (ii) TBV administered concurrently with PIFN [standard dosing arm (n = 19)].

RESULTS

More patients achieved undetectable virus or a ≥2-log(10) reduction of HCV RNA at Week 4 in the pre-dosing vs. the standard dosing arm [33% vs. 22% (P = 0.497)]. There was also a trend towards greater reduction in mean log(10) change in HCV RNA in the pre-dosing vs. the standard dosing arm, which was statistically significant at Day 1 [-0.34 ± 0.46 vs. 0.09 ± 0.32 (P < 0.003)] but not at other time points up to Week 24. No significant difference was observed in the rates of anaemia (haemoglobin <10 g/dL) between study arms (4.5% vs. 5.3%).

CONCLUSIONS

Pre-dosing TBV prior to starting PIFN produces a trend towards improved efficacy although statistical significance was not reached in this small patient population. These results warrant larger clinical trials of TBV pre-dosing.

Early dynamics of viremia in patients with genotype 1b chronic hepatitis C: Peg-IFNalpha2a shows earlier viral decline than peg-IFNalpha2b in combination therapy with ribavirin

Background

We aimed to assess differences in early viral dynamics following treatment with either peg-IFNα2a or peg-IFNα2b in combination with ribavirin in patients with chronic genotype 1b HCV infection.

Material/Methods

Sixty-one patients in the peg-IFNα2a + ribavirin treatment (group α2a) and 88 patients in the peg-IFNα2b + ribavirin treatment (group α2b) were retrospectively analyzed. The early dynamics of HCV RNA over 12 weeks were evaluated. Sustained virological response (SVR) was defined as undetectable HCV RNA at week 24 after end of therapy. First- (day 0–1) and second-phase (day 1–28) viral decline rates were calculated in accordance with theoretical formulae.

Results

Baseline HCV RNA concentrations were almost similar between the 2 groups. In group α2a, viral decline was significantly greater than in group α2b at weeks 4, 8, and 12. In group α2a, viral decline was significantly greater in SVR patients than in non-SVR patients at week 2, whereas significantly greater viral decline in SVR patients was found during weeks 1–12 in group α2b. The first-phase viral decline rate was significantly larger in group α2a than in group α2b (1.31±0.84 vs. 0.70±0.97 log IU/mL/day; p<0.0001). Within SVR patients, first-phase viral decline rate was significantly larger in group α2a compared with group α2b (1.45±0.85 vs. 0.78±1.0 log IU/mL/day; p<0.0001). Second-phase viral decline rate was comparable between the groups.

Conclusions

Peg-IFNα2a showed earlier viral decline than peg-IFNα2b and the difference was obvious, especially in the first-phase viral decline.

The protease inhibitor, GS-9256, and non-nucleoside polymerase inhibitor tegobuvir alone, with ribavirin, or pegylated interferon plus ribavirin in hepatitis C

Tegobuvir (GS-9190), a non-nucleoside nonstructural protein (NS)5B polymerase inhibitor, and GS-9256, an NS3 serine protease inhibitor, individually have activity against hepatitis C virus (HCV) genotype 1. The antiviral activity of tegobuvir and GS-9256 as oral combination therapy, or together with ribavirin (RBV) or pegylated interferon (Peg-IFN) alpha-2a and RBV, was assessed in a phase II, randomized, open-label trial. Treatment-naïve patients with genotype 1 HCV were assigned 28 days of tegobuvir 40 mg twice-daily (BID) and GS-9256 75 mg BID (n = 16), tegobuvir and GS-9256 plus RBV 1,000-1,200 mg daily (n = 15), or tegobuvir and GS-9256 plus Peg-IFN alpha-2a (180 μg once-weekly)/RBV (n = 15). The primary efficacy endpoint was rapid virologic response (RVR), with HCV RNA <25 IU/mL at day 28. After 28 days, all patients received Peg-IFN/RBV. All patients with viral rebound or nonresponse, defined as >0.5-log(10) increase in HCV RNA from nadir or <2-log decrease at day 5, initiated Peg-IFN/RBV immediately. Median maximal reductions in HCV RNA were -4.1 log(10) IU/mL for tegobuvir/GS-9256, -5.1 log(10) IU/mL for tegobuvir/GS-9256/RBV, and -5.7 log(10) IU/mL for tegobuvir/9256/Peg-IFN/RBV. RVR was observed in 7% (1 of 15) of patients receiving tegobuvir/GS-9256, 38% (5 of 13) receiving tegobuvir/GS-9256/RBV, and 100% (14 of 14) receiving tegobuvir/9256/PEG-IFN/RBV. The addition of Peg-IFN/RBV at day 28 or earlier resulted in HCV RNA <25 IU/mL at week 24 in 67% (10 of 15), 100% (13 of 13), and 94% (13 of 14) of patients in the three treatment groups. Transient elevations in serum bilirubin occurred in all treatment groups.

CONCLUSION

In genotype 1 HCV, adding RBV or RBV with Peg-IFN provides additive antiviral activity to combination therapy with tegobuvir and GS-9256.

Ribavirin-induced anemia in hepatitis C virus patients undergoing combination therapy

The current standard of care for hepatitis C virus (HCV) infection – combination therapy with pegylated interferon and ribavirin – elicits sustained responses in only ∼50% of the patients treated. No alternatives exist for patients who do not respond to combination therapy. Addition of ribavirin substantially improves response rates to interferon and lowers relapse rates following the cessation of therapy, suggesting that increasing ribavirin exposure may further improve treatment response. A key limitation, however, is the toxic side-effect of ribavirin, hemolytic anemia, which often necessitates a reduction of ribavirin dosage and compromises treatment response. Maximizing treatment response thus requires striking a balance between the antiviral and hemolytic activities of ribavirin. Current models of viral kinetics describe the enhancement of treatment response due to ribavirin. Ribavirin-induced anemia, however, remains poorly understood and precludes rational optimization of combination therapy. Here, we develop a new mathematical model of the population dynamics of erythrocytes that quantitatively describes ribavirin-induced anemia in HCV patients. Based on the assumption that ribavirin accumulation decreases erythrocyte lifespan in a dose-dependent manner, model predictions capture several independent experimental observations of the accumulation of ribavirin in erythrocytes and the resulting decline of hemoglobin in HCV patients undergoing combination therapy, estimate the reduced erythrocyte lifespan during therapy, and describe inter-patient variations in the severity of ribavirin-induced anemia. Further, model predictions estimate the threshold ribavirin exposure beyond which anemia becomes intolerable and suggest guidelines for the usage of growth hormones, such as erythropoietin, that stimulate erythrocyte production and avert the reduction of ribavirin dosage, thereby improving treatment response. Our model thus facilitates, in conjunction with models of viral kinetics, the rational identification of treatment protocols that maximize treatment response while curtailing side effects.

The treatment of HCV infection poses a major global health-care challenge today. The current standard of care, combination therapy with interferon and ribavirin, works in only about half of the patients treated. Because no alternatives are available yet for patients in whom combination therapy fails, identifying ways to improve response to combination therapy is critical. Increasing exposure to ribavirin does improve response but is associated with the severe side-effect, anemia. One way to maximize treatment response therefore is to increase ribavirin exposure to levels just below where anemia becomes intolerable. A second way is to supplement combination therapy with growth hormones, such as erythropoietin, that increase the production of red blood cells (erythrocytes) and compensate for ribavirin-induced anemia. Rational optimization of combination therapy thus relies on a quantitative description of ribavirin-induced anemia, which is currently lacking. Here, we develop a model of the population dynamics of erythrocytes in individuals exposed to ribavirin that quantitatively describes ribavirin-induced anemia. Model predictions capture several independent observations of ribavirin-induced anemia in HCV patients undergoing combination therapy, estimate the threshold ribavirin exposure beyond which anemia becomes intolerable, suggest guidelines for the usage of growth hormones, and facilitate rational optimization of therapy.

Role of ribavirin in HCV treatment response: now and in the future

IMPORTANCE OF THE FIELD

Ribavirin is a broad spectrum antiviral agent that is used with pegylated IFN (Peg-IFN) for HCV treatment. Ribavirin does not significantly reduce HCV viral load when used alone but increases rates of sustained virologic response (SVR) when combined with Peg-IFN. HCV genotype 1 infected patients require higher doses of ribavirin administered for a longer duration of time versus HCV genotypes 2 and 3 patients who respond effectively to Peg-IFN with lower doses of ribavirin and shorter duration of therapy. Higher serum concentrations of ribavirin are associated with higher response rates but also higher rates of hemolytic anemia which is a dose limiting side effect. Alternatives to current therapy are under clinical evaluation.

AREAS COVERED IN THIS REVIEW

Systematic literature review of ribavirin use in HCV patients from 1995 to 2009 was conducted.

WHAT THE READER WILL GAIN

To review the efficacy and safety of ribavirin in current HCV treatment and in new therapies in Phase III clinical trials.

TAKE HOME MESSAGE

Ribavirin is a drug which is essential to produce higher SVR rates both with Peg-IFN and HCV protease inhibitors currently in Phase III clinical trials. Thus, ribavirin is and will remain an important drug to achieving higher SVR rates in HCV infected persons.

Management of nonresponsive hepatitis C

More than 50% of hepatitis C virus (HCV)-infected patients do not respond to the classical pegylated interferon (PEG-IFN)/ribavirin combination therapy. However, failing to respond to one course of treatment is not synonymous of therapy failure and retreatment is often beneficial. Alternative retreatment strategies include repeating the classical standard of care with an optimized drug regimen and adherence, including ribavirin serum concentration adjustment, correcting, if at all possible, comorbidities, and the addition of new specific anti-HCV molecules to the backbone of pegylated interferon/ribavirin. Options of retreatment should include consensus and natural interferons. For patients with advanced disease exposed to a high risk of lethal complications, customized maintenance therapy could be an effective option since it may slow down complications in some patients. Since low-dose interferon monotherapy is not sufficient, such a maintenance therapy remains to be verified via clinical trials. New possibilities of noninvasive assessment of fibrosis and the use of genetic tests to predict fibrosis progression and responsiveness to interferon are major emerging opportunities that run parallel to the revolution of the pharmacologic armentarium.

Ribavirin monotherapy for chronic hepatitis C

BACKGROUND

Hepatitis C is a major cause of liver-related morbidity and mortality. A high proportion of patients never experience symptoms. Peginterferon plus ribavirin is the recommended treatment for chronic hepatitis C. However, ribavirin monotherapy may be considered for some patients.

OBJECTIVES

To assess the beneficial and harmful effects of ribavirin monotherapy for patients with chronic hepatitis C.

SEARCH STRATEGY

We identified trials through electronic databases, manual searches of bibliographies and journals, authors of trials, and pharmaceutical companies until March 2009.

SELECTION CRITERIA

We included all randomised trials irrespective of blinding, language, or publication status comparing ribavirin versus no intervention, placebo, or interferon for chronic hepatitis C.

DATA COLLECTION AND ANALYSIS

The primary outcome measures were serum sustained virological response (loss of hepatitis C virus RNA at least six months after treatment), liver-related morbidity plus all-cause mortality, and adverse events. Secondary outcome measures were end of treatment virological response, biochemical response (transaminase activity), and histological response. Randomisation methods, blinding, data handling, and funding were extracted as measures of bias control. Random-effects and fixed-effect meta-analyses were performed for all outcomes. We only present the results of the fixed-effect model if both models provide the same result regarding statistical significance. We present data as risk difference (RD) with 95% confidence intervals (CI).

MAIN RESULTS

We included 14 randomised trials with 657 patients. The majority of trials had unclear control of bias. Compared with placebo or no intervention, ribavirin had no significant effect on the sustained virological response (RD 0%, 95% CI -2% to 3%, five trials) or end of treatment virological response (RD 0% 95% CI -3% to 3%, ten trials). Ribavirin had no significant effect on liver-related morbidity plus mortality (RD 0%, 95% CI -2% to 3%, 11 trials). Ribavirin significantly increased the risk of adverse reactions, including anaemia. Ribavirin significantly improved end of treatment biochemical and histological response but not the sustained biochemical response. Ribavirin was significantly inferior to interferon regarding virological and biochemical responses (five trials).

AUTHORS' CONCLUSIONS

Ribavirin seems without beneficial effects on serum virological response and liver-related morbidity or mortality, and significantly increased the risk of adverse reactions. Ribavirin monotherapy seems significantly inferior to interferon monotherapy. The total number of included patients is small, and more trials are perhaps needed. The use of ribavirin monotherapy for chronic hepatitis C cannot be recommended outside randomised trials.

Ribavirin: current role in the optimal clinical management of chronic hepatitis C

Ribavirin in combination with peginterferon alfa shows strong clinical efficacy against chronic hepatitis C, and is now established as the standard of care. However, the precise role of ribavirin is still being defined, suggesting that optimal ribavirin dose should be maintained over the whole treatment period. Ribavirin dosage varies by bodyweight for genotype 1 disease (1000mg/day in patients <or =75kg and 1200mg/day in patients >75kg), whereas 800mg/day is sufficient to ensure optimal response in all genotype 2/3 patients. Similarly, genotype 1 patients benefit from 48 weeks of therapy, while 24 weeks is sufficient for genotype 2/3 disease. Recent data suggest treatment success is dependent on cumulative ribavirin exposure, as patients who receive <60% of the planned dose have lower response rates, regardless of whether reductions are from temporary interruptions or premature cessation of therapy. All patients should be monitored for hemolytic anemia, as early diagnosis allows management through small dose reductions and stepwise return to the target dose, maximizing cumulative exposure. Despite these recent advances in our knowledge, many questions remain, such as whether the role of ribavirin will change or even be eliminated as new therapies are developed.

Ribavirin in the treatment of chronic hepatitis C

BACKGROUND AND AIM

Current practice guidelines recommend that individuals chronically infected with the hepatitis C virus (HCV) be treated with pegylated interferon plus ribavirin. Ribavirin, however, is associated with serious adverse events (AE), especially anemia. We review its mechanism of action, its importance in treating chronic hepatitis C (CHC) patients, the AE associated with its use, and techniques used to lessen these AE.

METHODS

Medline searches were performed using the keywords ribavirin and hepatitis, together with the keywords mechanism, anemia, liver transplant, renal function, pharmacokinetics, and dose reduction. Searches of abstracts of recent Digestive Diseases Week, American Association for the Study of Liver Diseases, and European Association for the Study of Liver Diseases meetings were also performed.

RESULTS

Ribavirin may be effective in treating CHC by affecting the virus or the host; for example by inducing viral mutations, blocking cellular enzymes, or affecting the host immune response. Although the pegylated interferons are the primary drugs used to treat CHC, a combination with ribavirin is more effective than pegylated interferon alone. Ribavirin-associated AE may be lessened by ribavirin dose reductions and by maintenance of the hematocrit.

CONCLUSIONS

Treatments of ribavirin toxicities, especially anemia, can allow patients to continue full-dose combination therapy with peginterferon and ribavirin, enhancing their probability of attaining a sustained virologic response (SVR). Treatment of CHC should be tailored to individual patients, especially those with renal dysfunction, and should include agents that treat the side-effects of CHC treatment. Monitoring of plasma ribavirin concentrations during treatment may help in the future.

Ribavirin considerations in treatment optimization

Ribavirin is a guanosine analogue that has little antiviral activity when used alone, but considerably enhances the efficacy of conventional and pegylated interferon in the treatment of hepatitis C virus (HCV). The precise mode of action of ribavirin is not fully understood; however, it is crucial for the achievement of high sustained virological response (SVR) rates by enhancing virological response and reducing relapse rates. Data from several studies have confirmed that higher initial doses of ribavirin lead to higher SVR rates. Furthermore, intensified ribavirin dosing might also improve SVR rates in ‘difficult-to-cure’ patients. It is also important to minimize ribavirin dose reductions to promote high SVR rates and to maintain ribavirin levels throughout treatment to prevent viral breakthrough and relapse. The pharmacokinetic profile of ribavirin reveals a long elimination half-life due to accumulation in the blood, such that its side-effect profile includes haemolytic anaemia. Therefore, finding the optimal ribavirin dose requires a balance between efficacy and its associated side effects to ensure improved patient outcomes. Here, we discuss how optimizing the ribavirin component of combined therapy for HCV is an essential part of treatment optimization.

Replicative homeostasis III: implications for antiviral therapy and mechanisms of response and non-response

While improved drug regimens have greatly enhanced outcomes for patients with chronic viral infection, antiviral therapy is still not ideal due to drug toxicities, treatment costs, primary drug failure and emergent resistance. New antiviral agents, alternative treatment strategies and a better understanding of viral pathobiology, host responses and drug action are desperately needed. Interferon (IFN) and ribavirin, are effective drugs used to treat hepatitis C (HCV), but the mechanism(s) of their action are uncertain. Error catastrophe (EC), or precipitous loss of replicative fitness caused by genomic mutation, is postulated to mediate ribavirin action, but is a deeply flawed hypothesis lacking empirical confirmation. Paradoxically ribavirin, a proven RNA mutagen, has no impact on HCV viraemia long term, suggesting real viruses, replicating in-vitro, as opposed to mathematical models, replicating in-silico, are likely to resist EC by highly selective replication of fit (~consensus sequence) genomes mediated, in part, by replicative homeostasis (RH), an epicyclic mechanism that dynamically links RNApol fidelity and processivity and other viral protein functions. Replicative homeostasis provides a rational explanation for the various responses seen during treatment of HCV, including genotype-specific and viral load-dependent differential response rates, as well as otherwise unexplained phenomena like the transient inhibition and rebound of HCV viraemia seen during ribavirin monotherapy. Replicative homeostasis also suggests a primarily non-immunological mechanism that mediates increased immune responsiveness during treatment with ribavirin (and other nucleos(t)ide analogues), explicating the enhanced second-phase clearance of HCV ribavirin promotes and, thus, the apparent immunomodulatory action of ribavirin. More importantly, RH suggests specific new antiviral therapeutic strategies.

Vitamin B12 reduces ribavirin-induced genotoxicity in phytohemaglutinin-stimulated human lymphocytes

Ribavirin, an N-glycosyl nucleoside (1-beta-D-ribofuranosyl-1, 2, 4-triazole-3 carboxamide), is a synthetic purine nucleoside analogue with a broad spectrum of antiviral activity, however, its high toxicity poses a major disadvantage of its use as a therapeutic. Various studies have shown that vitamin B12 plays a significant role in maintaining the stability of the human genome. We therefore investigated the potential beneficial effect of vitamin B12 in reducing ribavirin-induced genotoxicity. To test this, we used the cytokinesis-block micronucleus (CBMN) assay. Human blood cells were treated in vitro with increasing doses of ribavirin (0.05, 0.17, 0.32, 0.47 and 0.65 micromol/ml) for three different periods of time (2, 4 and 17 hrs). Duplicate cultures were supplemented with 50 mul of vitamin B12 during the drug treatment (final concentration of 13.5 microg/ml). Micronuclei formation and cell proliferation potential were then scored in both sets of samples and the corresponding controls. The results showed that supplementation with vitamin B12 lowered the frequency of micronuclei (Z = 2.02, p < 0.04) and recovered the proliferation potential of the treated cells for each treatment period, except for the conditions with the highest concentration of ribavirin and the shortest time. These observations underscore the unique beneficial effects of vitamin B12 in reducing genotoxicity, particularly by recovering the proliferation potential of treated cells, as demonstrated by the decrease in mononucleated cells and enhancement of binucleated and polynucleated cells. The mechanism by which vitamin B12 reduces ribavirin-induced genotoxicity is related to de novo synthesis of nucleotides, and is worthy of further investigation.

Viral kinetics in the treatment of chronic hepatitis C

Hepatitis C virus (HCV) is a major cause of chronic hepatitis and hepatic fibrosis, and chronic infection can frequently progress to cirrhosis, end-stage liver disease and hepatocellular carcinoma. Treatment with pegylated interferons (INFs) plus ribavirin has been shown to be more effective than pegylated INFs alone or standard INFs with or without ribavirin. The early response of HCV to treatment with peg-INF has been used to predict treatment outcomes in infected patients, emphasizing the importance of viral kinetics and genotyping in their treatment. Mathematic modelling of viral dynamics has shown the importance of optimal doses of drug, with early virologic response at week 12 predictive of sustained virologic response. Maintaining INF concentration above a therapeutically effective level is necessary to prevent viral rebound and subsequent treatment failure. Once-weekly dosing with peg-INF-alpha2a, which has a longer half-life than other forms of INF, plus daily dosing with ribavirin, has been shown to be effective in reducing viral load.

Modelling how ribavirin improves interferon response rates in hepatitis C virus infection

Nearly 200 million individuals worldwide are currently infected with hepatitis C virus (HCV). Combination therapy with pegylated interferon and ribavirin, the latest treatment for HCV infection, elicits long-term responses in only about 50% of patients treated. No effective alternative treatments exist for non-responders. Consequently, significant efforts are continuing to maximize response to combination therapy. However, rational therapy optimization is precluded by the poor understanding of the mechanism(s) of ribavirin action against HCV. Ribavirin alone induces either a transient early decline or no decrease in HCV viral load, but in combination with interferon it significantly improves long-term response rates. Here we present a model of HCV dynamics in which, on the basis of growing evidence, we assume that ribavirin decreases HCV infectivity in an infected individual in a dose-dependent manner. The model quantitatively predicts long-term response rates to interferon monotherapy and combination therapy, fits observed patterns of HCV RNA decline in patients undergoing therapy, reconciles conflicting observations of the influence of ribavirin on HCV RNA decline, provides key insights into the mechanism of ribavirin action against HCV, and establishes a framework for rational therapy optimization.

Ribavirin suppresses eIF4E-mediated oncogenic transformation by physical mimicry of the 7-methyl guanosine mRNA cap

The eukaryotic translation initiation factor eIF4E is deregulated in many human cancers, and its overexpression in cells leads to malignant transformation. Oncogenic properties of eIF4E are directly linked to its ability to bind 7-methyl guanosine of the 5' mRNA. Here, we observe that the antiviral guanosine analogue ribavirin binds to eIF4E with micromolar affinity at the functional site used by 7-methyl guanosine mRNA cap, competes with eIF4E:mRNA binding, and, at low micromolar concentrations, selectively disrupts eIF4E subcellular organization and transport and translation of mRNAs posttranscriptionally regulated by eIF4E, thereby reducing levels of oncogenes such as cyclin D1. Ribavirin potently suppresses eIF4E-mediated oncogenic transformation of murine cells in vitro, of tumor growth of a mouse model of eIF4E-dependent human squamous cell carcinoma in vivo, and of colony formation of eIF4E-dependent acute myelogenous leukemia cells derived from human patients. These findings describe a specific, potent, and unforeseen mechanism of action of ribavirin. Quantum mechanical and NMR structural studies offer directions for the development of derivatives with improved cytostatic and antiviral properties. In all, ribavirin's association with eIF4E may provide a pharmacologic means for the interruption of posttranscriptional networks of oncogenes that maintain and enhance neoplasia and malignancy in human cancer.

Predominance of type 1 (Th1) cytokine production in the liver of patients with HCV-associated mixed cryoglobulinemia vasculitis

BACKGROUND/AIMS

Patients with hepatitis C virus (HCV) mixed cryoglobulinemia (MC) vasculitis have a higher mortality rate and more frequent incidence of cirrhosis than their cryoglobulin-negative counterparts. To compare the cytokine profile of liver-infiltrating T cells in HCV-infected patients with or without MC vasculitis.

METHODS

Hepatic biopsy specimens were obtained from HCV infected patients with and without MC vasculitis. Using intracellular staining and flow cytometry, we assessed the ability of freshly isolated liver T cells from these biopsies to produce IFN-gamma, TNF-alpha, IL-2, IL-4, and IL-10 in response to stimulation with PMA and ionomycin.

RESULTS

HCV-MC vasculitis patients compared to HCV-MC negative controls have an enhanced hepatic T cells production of Th1-type cytokines [i.e. TNF-alpha(30.3 +/- 13% vs. 15.5 +/- 5%, P = 0.01), IL-2 (20.2 +/- 9% vs. 10 +/- 4%, P = 0.01) and IFN-gamma (22.2 +/- 11% vs. 9.4 +/- 4%, P = 0.008)], whereas IL-10, a representative Th2-type cytokine, was significantly lower (7.2 +/- 4% vs. 17 +/- 7%, P = 0.01).

CONCLUSIONS

T cell from the liver of HCV-MC vasculitis patients display a significantly augmented liver Th1 profile compared to MC-negative controls. This enhanced production of type-1 cytokines may account for a more severe course of liver disease.

Auto-immunisation induite par l’interféron alpha dans un contexte d’hépatite virale C chronique

We report the case of a 56 year-old woman with post-transfusion chronic hepatitis C who presented with a severe ALT flare up associated with a rapid progression of liver fibrosis during interferon alpha 2b therapy. Several hypotheses were considered to explain the etiology of this ALT flare: there was no viral super infection by other hepatotropic viruses, no toxic hepatitis, no metabolic disease, and no other specific liver diseases could be identified. HLA typing showed a specific profile A1 B8 DR3 (risk factor of auto-immunization during interferon alpha therapy) with antinuclear antibodies and anti smooth muscle antibodies. This case suggests that auto-immunization induced by interferon alpha should be investigated in case of ALT flare that is not followed by an HCV breakthrough.

An in vitro system combined with an in-house quantitation assay for screening hepatitis C virus inhibitors

Hepatitis C virus (HCV) infection is a serious global health problem. Interferon-alpha (IFN-alpha) and ribavirin have demonstrated efficacy in the treatment of HCV infection; however, these therapies display many side effects. To screen the anti-HCV compounds from plants, we established an in vitro model for inoculation of HCV by centrifugation-facilitated method. The HCV RNA molecules were then quantitated by nested competitive reverse transcription-polymerase chain reaction (cRT-PCR) using fluorescein-labeled primers, and analyzed by ABI Prism 310. The positive and negative strands of HCV RNA were detectable in Vero cells on Day 7 post-infection, suggesting that the HCV RNA was present in the cell model system. The cell culture system was further used to screen the anti-HCV activities of 4 Chinese herbal formulas and 15 formula components. IFN-alpha showed an antiviral effect. The formulas exhibited no anti-HCV activities, while Arnebia euchroma, Thlaspi arvense, and Poncirus trifoliata displayed anti-HCV activities. Therefore, these results pointed out the possibility by using the cell culture system established in this study to screen the herb extracts for their anti-HCV activities.

Interferons, interferon inducers, and interferon-ribavirin in treatment of flavivirus-induced encephalitis in mice

We evaluated the prophylactic and therapeutic efficacy of interferon alpha-2b, pegylated interferon alpha-2b, poly(I. C), and Ampligen against Modoc virus encephalitis in an animal model for flavivirus infections. All compounds significantly delayed virus-induced morbidity (paralysis) and mortality (due to progressive encephalitis). Viral load (as measured on day 7 postinfection) was significantly reduced by 80 to 100% in the serum, brain, and spleen in mice that had been treated with either interferon alpha-2b, pegylated interferon alpha-2b, poly(I. C), or Ampligen. We also studied whether a combination of interferon alpha-2b and ribavirin (presently the standard therapy for the treatment of infections with hepatitis C virus) would be more effective than treatment with interferon alone. However, ribavirin did not enhance the inhibitory effect of interferon therapy in this animal model for flavivirus infections.

Interferon-alpha and ribavirin treatment in patients with hepatitis C virus-related systemic vasculitis

OBJECTIVE

Hepatitis C virus (HCV)-related vasculitis may involve multiple organs, including the skin, kidneys, and nervous system, and may be life-threatening. Although HCV is increasingly recognized as a cause of systemic vasculitis, limited data are available regarding the optimal treatment of this potentially serious condition. Therefore, we retrospectively analyzed the response to treatment in patients with chronic hepatitis C complicated by systemic vasculitis who had received antiviral therapy with interferon-alpha (IFNalpha) and ribavirin.

METHODS

This retrospective study included 27 patients with systemic vasculitis and chronic HCV infection. Each patient had received treatment with IFNalpha and ribavirin for at least 6 months. The response to antiviral treatment was analyzed by comparing clinical, immunologic, and virologic data at the time of entry and during followup. Clinical response was defined according to the evolution of weight, arthralgia, nervous system, renal system, and cutaneous involvement. The virologic and immunologic responses were defined by the absence of HCV RNA and the absence of cryoglobulinemia, respectively, both 6 months after stopping antiviral therapy and at the end of followup.

RESULTS

Patients received IFNalpha for a mean +/- SD of 20 +/- 14 months and ribavirin (at a mean +/- SD dosage of 895 +/- 250 mg/day) for 14 +/- 12 months. Other treatments included low-dose corticosteroids and plasma exchange. After a mean +/- SD followup of 57 +/- 29 months, 25 of 27 patients are alive and are being followed up as outpatients. Because of the heterogeneity of anti-HCV treatments received, the main results were stratified according to patients with 6 months of followup after stopping antiviral treatment (group 1, n = 14) and those who were still undergoing antiviral therapy at the time of analysis (group 2, n = 13). Nine patients in group 1 had a sustained virologic response and were clinical and immunologic complete responders. Four patients in group 1 were virologic nonresponders, and 3 of these patients had partial clinical and immunologic responses. Overall, 10 patients in group 1 had a complete clinical and immunologic response of their vasculitis (all 9 of the sustained virologic responders and 1 of the 5 patients who remained viremic). At the end of followup, 7 patients in group 2 were negative for HCV RNA; 6 were complete clinical responders. Among the other 6 patients in group 2, who had persistent viremia, 4 had a partial clinical response. Among the patients in group 1, HCV RNA was more often undetectable and genotype 1 was less frequent in complete clinical responders compared with partial/nonresponders. Age, sex, clinical vasculitic involvement, mean duration or total cumulative dose of IFNalpha or ribavirin, and use of steroids or plasmapheresis did not differ significantly according to clinical response.

CONCLUSION

Treatment with IFNalpha and ribavirin can achieve a complete clinical response in most patients with HCV-related systemic vasculitis. Complete clinical response correlates with the eradication of HCV.

Nucleotide triphosphatase/helicase of hepatitis C virus as a target for antiviral therapy

The RNA nucleoside triphosphatase (NTPase)/helicases represent a large family of proteins that are detected in almost all biological systems where RNA plays a central role. The enzymes are capable of enzymatically unwinding duplex RNA structures by disrupting the hydrogen bonds that keep the two strands together. The strand separating activity is associated with hydrolysis of nucleoside triphosphate (NTP). Because of this, potential specific inhibitors of NTPase/helicases could act by one or more of the following mechanisms: (i) inhibition of NTPase activity by interference with NTP binding, (ii) inhibition of NTPase activity by an allosteric mechanism and (iii) inhibition of the coupling of NTP hydrolysis at the unwinding reaction. There are also other inhibitory mechanisms conceivable, which may involve a modulation of the interaction of the enzyme with its RNA substrate, for example, (iv) the competitive inhibition of RNA binding and (v) the inhibition of the unwinding by sterical blockade of the translocation of the NTPase/helicase along the polynucleotide chain. NTPase/helicase has also been identified in the viral genome of hepatitis C virus (HCV) which is a member of the Flaviviridae family. It is conceivable that the inhibition of the unwinding activity of the enzyme leads to the inhibition of virus replication and this may represent a novel antiviral strategy. This review updates the current spectrum of inhibitors targeting different mechanisms by which the NTPase and/or helicase activities of the HCV NTPase/helicase are inhibited. Consequently, some of the compounds might be important as antiviral agents against HCV.

Hepatitis C virus RNA-dependent RNA polymerase (NS5B) as a mediator of the antiviral activity of ribavirin

Ribavirin is administered in combination with interferon-alpha for treatment of hepatitis C virus (HCV) infection. Recently, we demonstrated that the antiviral activity of ribavirin can result from the ability of a viral RNA polymerase to utilize ribavirin triphosphate and to incorporate this nucleotide with reduced specificity, thereby mutagenizing the genome and decreasing the yield of infectious virus (Crotty, S., Maag, D., Arnold, J. J., Zhong, W., Lau, J. Y., Hong, Z., Andino, R., and Cameron, C. E. (2000) Nat. Med. 6, 1375-1379). In this study, we performed a quantitative analysis of a novel HCV RNA polymerase derivative that is capable of utilizing stably annealed primer-template substrates and exploited this derivative to evaluate whether lethal mutagenesis of the HCV genome is a possible mechanism for the anti-HCV activity of ribavirin. These studies demonstrate HCV RNA polymerase-catalyzed incorporation of ribavirin opposite cytidine and uridine. In addition, we demonstrate that templates containing ribavirin support CMP and UMP incorporation with equivalent efficiency. Surprisingly, templates containing ribavirin can also cause a significant block to RNA elongation. Together, these data suggest that ribavirin can exert a direct effect on HCV replication, which is mediated by the HCV RNA polymerase. We discuss the implications of this work on the development of nucleoside analogs for treatment of HCV infection.

The mechanism of action of ribavirin: lethal mutagenesis of RNA virus genomes mediated by the viral RNA-dependent RNA polymerase

Ribavirin (1-beta-D-ribofuranosyl-1,2,4-triazole) is a broad-spectrum antiviral nucleoside that is currently used in combination with interferon-alpha to treat hepatitis C virus infection and as a monotherapy to treat severe cases of respiratory syncytial virus infection and Lassa fever virus infection. The mechanism of action of ribavirin has been studied for decades. These studies have suggested that the antiviral activity of ribavirin may be related to its ability to cause a decrease in intracellular guanosine triphosphate pools, to inhibit capping of viral transcripts or to suppress humoral and cellular immune responses. Last year, another possibility was added to this list. The new proposition is that ribavirin, when converted to the triphosphate, is utilized by the viral RNA-dependent RNA polymerase and causes lethal mutagenesis of the viral genome. In this article, the data supporting this new hypothesis are reviewed. We discuss the implications of these data on alternative explanations for the apparent failure of ribavirin monotherapy in the treatment of hepatitis C virus infection, connections between developmental defects induced by ribavirin and posttranscriptional gene silencing/RNA interference, and the use of lethal mutagenesis and related concepts as strategies for antiviral therapy.

[Peripheral neuropathy and hepatitis C virus infection: more than cryoglobulinemia]

PURPOSE

To study characteristics of peripheral neuropathies associated with hepatitis C virus infection.

METHODS

A study of two groups of four patients with peripheral neuropathy and infected with hepatitis C virus, and a literature review.

RESULTS

We observed four cases of peripheral neuropathy in patients with hepatitis C virus infection with persistent negativity of mixed cryoglobulinemia, and with no purpura, rheumatoid factor, or low C4 level. Neuropathy improved with treatment in three patients between 8 and 28 months after treatment was begun. We report four other observations of peripheral neuropathy with mixed cryoglobulinemia. Worsening of peripheral neuropathy was observed 2 to 13 weeks after initiation of interferon alpha despite improvement of hepatic parameters. After stopping interferon, peripheral neuropathy worsened (one case), stabilized (one case), or improved (two cases).

DISCUSSION

In patients infected with hepatitis C virus, peripheral neuropathy can be due to mixed cryoglobulinemia, periarteritis nodosa, and perhaps hepatitis C virus itself as suggested by our first observations. Low doses of interferon alpha may worsen peripheral neuropathy in patients with mixed cryoglobulinemia, as suggested in our later observations.

Monitoring virological responses to interferon-ribavirin and interferon monotherapy of chronic hepatitis C re-treated due to relapse or non-response

Adding the nucleoside analog ribavirin (RBV) to interferon (IFN) for treatment of HCV has improved the sustained response rates, but the mechanism by which RBV mediates viral clearance is not fully understood. In this study, a highly sensitive method (Codes Amplicor HCV Monitor) was used to monitor the early (first 12 weeks of therapy) and long-term virological response in 20 patients who were treated first with IFN and later, due to non-sustained response, with IFN-RBV. All 10 IFN relapsers displayed a prompt virological response at week 4 to both IFN and IFN-RBV therapy; nine of them showed a sustained response to IFN-RBV. Out of 10 IFN non-responders, five showed a sustained response to IFN-RBV. Four of these were HCV RNA-negative at week 4 of IFN-RBV therapy and two of them had a transient early virological response (RNA-negative at weeks 4-8) to IFN alone. Overall, of the 14 patients (nine IFN relapsers, five IFN non-responders) with a sustained response to IFN-RBV, 11 and 13 had HCV RNA below 2000 copies/ml at week 4 of IFN and IFN-RBV, respectively, as compared with one and one of six patients without a sustained response to IFN-RBV (p < 0.02). Thus, addition of RBV to IFN increased both viral clearance during the first 12 weeks of therapy and the rate of sustained response. Loss of viremia at week 4 of IFN was associated with a sustained response to IFN-RBV and was seen in 11 of 13 patients (85%) with genotypes 2 or 3, as compared with one of seven patients (14%) with genotype 1 (p = 0.0044).

Evolution of hepatitis C virus genome in chronically infected patients receiving ribavirin monotherapy

Recent results of clinical trials suggest that combination of interferon and ribavirin exhibits an enhanced antiviral effect in the treatment of chronic hepatitis C. To investigate the effect of ribavirin on hepatitis C virus (HCV) infection, we analysed the evolution of the genetic heterogeneity of HCV in relation to the anti-HCV humoral response in patients treated by ribavirin alone. The study population included 35 patients with liver biopsy proven chronic hepatitis C infected with HCV genotype 1. Among them, 26 were treated with ribavirin for at least 12 months and nine untreated patients served as a control group. Serum samples were analysed before and at 6 and 12 months of therapy. Three regions of the HCV genome, i.e. HVR1, a domain of NS5A including part of the interferon sensitivity determining region (ISDR), and a segment of NS5B, were amplified by RT-PCR using specific primers. The PCR products were then studied using single-strand conformation polymorphism (SSCP) analysis followed by either direct sequencing, or cloning and sequencing. In parallel, the humoral anti-E1 response was studied using an ELISA (Innotest HCV E1Ab, Innogenetics). The results of HCV genome analysis showed no significant effect on the amino acid sequence evolution of the HVR1, NS5A and NS5B regions of HCV. Analysis of a phylogenetic tree from the major quasispecies variants showed the absence of correlation with ribavirin response, and the absence of selection of viral strains during ribavirin treatment. A trend towards a decrease in the anti-E1 Ab response was also observed. Altogether these results suggest that ribavirin may not exhibit a direct antiviral effect, but may trigger a favourable response to interferon by modulating the immune response against HCV.

Treatment of chronic hepatitis C with amantadine hydrochloride in patients who had not responded to previous treatment with interferon-alpha and/or ribavirin

Seven women and 3 men infected with hepatitis C virus, all of whom had failed to respond to therapy with either IFN-alpha or IFN and ribavirin, were treated with 200 mg/day of amantadine hydrochloride for 12 months. We found a significant decrease of serum ALT activity without any decrease in virus load. These results suggest that amantadine hydrochloride should not be used as monotherapy for patients who do not respond to treatment with IFN-alpha and/or ribavirin.

Perspectives for the treatment of infections with Flaviviridae

The family Flaviviridae contains three genera: Hepacivirus, Flavivirus, and Pestivirus. Worldwide, more than 170 million people are chronically infected with Hepatitis C virus and are at risk of developing cirrhosis and/or liver cancer. In addition, infections with arthropod-borne flaviviruses (such as dengue fever, Japanese encephalitis, tick-borne encephalitis, St. Louis encephalitis, Murray Valley encephalitis, West Nile, and yellow fever viruses) are emerging throughout the world. The pestiviruses have a serious impact on livestock. Unfortunately, no specific antiviral therapy is available for the treatment or the prevention of infections with members of the Flaviviridae. Ongoing research has identified possible targets for inhibition, including binding of the virus to the cell, uptake of the virus into the cell, the internal ribosome entry site of hepaciviruses and pestiviruses, the capping mechanism of flaviviruses, the viral proteases, the viral RNA-dependent RNA polymerase, and the viral helicase. In light of recent developments, the prevalence of infections caused by these viruses, the disease spectrum, and the impact of infections, different strategies that could be pursued to specifically inhibit viral targets and animal models that are available to study the pathogenesis and antiviral strategies are reviewed.

Perspectives for the treatment of infections with Flaviviridae

The family Flaviviridae contains three genera: Hepacivirus, Flavivirus, and Pestivirus. Worldwide, more than 170 million people are chronically infected with Hepatitis C virus and are at risk of developing cirrhosis and/or liver cancer. In addition, infections with arthropod-borne flaviviruses (such as dengue fever, Japanese encephalitis, tick-borne encephalitis, St. Louis encephalitis, Murray Valley encephalitis, West Nile, and yellow fever viruses) are emerging throughout the world. The pestiviruses have a serious impact on livestock. Unfortunately, no specific antiviral therapy is available for the treatment or the prevention of infections with members of the Flaviviridae. Ongoing research has identified possible targets for inhibition, including binding of the virus to the cell, uptake of the virus into the cell, the internal ribosome entry site of hepaciviruses and pestiviruses, the capping mechanism of flaviviruses, the viral proteases, the viral RNA-dependent RNA polymerase, and the viral helicase. In light of recent developments, the prevalence of infections caused by these viruses, the disease spectrum, and the impact of infections, different strategies that could be pursued to specifically inhibit viral targets and animal models that are available to study the pathogenesis and antiviral strategies are reviewed.

Hepatitis C: role of the advanced practice nurse

Hepatitis C virus (HCV) is a common but insidious and indolent viral infection that can lead to chronic hepatitis, cirrhosis, and hepatocellular carcinoma. This article provides the advanced practice nurse with current information on prevalence, incidence, spread, and clinical course of hepatitis C. It presents a discussion of the methods of diagnosis, treatment, and management of affected patients. To date, the diagnosis of hepatitis C in the United States has been serendipitous because no surveillance and screening programs have been established. It has been estimated that approximately 4 million persons in the United States are infected with HCV, with only 30% presently diagnosed. Patients with hepatitis C must make informed choices regarding their care and treatment. As more people are diagnosed with hepatitis C, the advanced practice nurse is at the forefront of providing information about spread and diagnosis, treatment options available, and potential side effects of antiviral therapy. The decision to treat chronic HCV must be made in collaboration with other medical experts in hepatology and antiviral therapy, and it must be made with knowledge and understanding of all facets of the disease process and adverse effects of therapy.