[Delta hepatitis: Epidemiology, diagnostic, natural history and treatment]. / Hépatite Delta : épidémiologie, diagnostic, histoire naturelle et traitements.

Hepatitis B virus is a small enveloped RNA virus, which replicates independently but requires the hepatitis B virus (HBV) to provide the envelope proteins necessary for the assembly of its own viral particles. Approximately 5% of chronic hepatitis B virus carriers are infected with HDV. HBV vaccination remains the best preventive treatment for HDV. All HBV patients should be screened for HDV (anti-HDV serology). In case of positive HDV serology, HDV replication (HDV RNA) should be investigated using a sensitive and specific technique. Hepatitis Delta is often complicated by cirrhosis and hepatocellular carcinoma (HCC). For this reason, every patient with Delta cirrhosis should be screened for HCC by abdominal ultrasound every 6 months. The historical treatment was based on PEG-IFN with many side effects. A new treatment has been approved, Bulevirtide (Hepcludex®) an HDV/HBV entry inhibitor, for any patient with chronic hepatitis Delta infection (CHD) with active replication (except in decompensated cirrhosis), at a dose of 2mg/day by subcutaneous injection. The exact duration on-treatment is unknown, thus treatment should be continued if clinical benefit is observed.

Resistance characterization of ledipasvir and velpatasvir in hepatitis C virus genotype 4.

HCV genotype 4 (GT4) has often been overlooked in drug development, even though it infects ~20 million people worldwide. Ledipasvir/sofosbuvir and sofosbuvir/velpatasvir were highly efficacious in GT4 HCV-infected patients from GS-US-337-1119 and GS-US-342-1138. Here, we characterize the resistance profile of ledipasvir (LDV) and velpatasvir (VEL) in patients with GT4 HCV infection. NS5A deep-sequencing was performed for 454 patients infected with HCV GT4 at baseline, including 44 patients enrolled in GS-US-337-1119 and 116 patients enrolled in GS-US-342-1138, and at relapse for patients with virologic failure. LDV and VEL susceptibilities of 56 patient isolates were determined. In GS-US-337-1119, SVR12 rates were 100% for all subtypes except 4b and 4r. Phenotypic assessment of 56 HCV NS5A patient isolates from various GT4 subtypes indicated that LDV had high potency for the common subtypes 4a/d, and subtypes 4c/f/k/l/m/n/o/p/r/t despite the presence of resistance-associated substitutions (RASs). For the rare GT4b, LDV median EC50 was higher, but with a broad range of individual values. Importantly, all GT4b isolates tested had 2-4 NS5A RASs, some including Y93H. Similarly, the 2 GT4r infected patients who had virologic relapse had rare triple RASs. Reversion of these substitutions to the consensus residue significantly increased LDV susceptibility. In GS-US-342-1138, all patients achieved SVR12, regardless of their subtype or presence of RASs. In vitro data confirmed that VEL is potent against all GT4 isolates tested. LDV and VEL are potent antiviral drugs, estimated to be effective against >95% and >99%, respectively, of GT4 HCV isolates.

Sofosbuvir and velpatasvir with or without voxilaprevir in direct-acting antiviral-naïve chronic hepatitis C: patient-reported outcomes from POLARIS 2 and 3.

BACKGROUND: Chronic hepatitis C infection leads to impairment of patient-reported outcomes (PROs). Treatment with direct-acting antiviral regimens results in short- and long-term improvement of these outcomes. AIM: To assess PROs in patients treated with a newly developed direct-acting antiviral, a fixed-dose combination of sofosbuvir/velpatasvir (SOF/VEL) with/without voxilaprevir (VOX). METHODS: The PRO data were collected from participants of POLARIS-2 and POLARIS-3 clinical trials (DAA-naïve, all HCV genotypes). Participants self-administered SF-36v2, FACIT-F, CLDQ-HCV and WPAI:SHP instruments at baseline, during treatment, and in follow-up. RESULTS: Of 1160 patients, 611 received SOF/VEL/VOX and 549 received SOF/VEL (52.8 ± 11.0 years, 55.9% male, 75.4% treatment-naïve, 33.9% cirrhotic). The sustained viral response at 12 weeks (SVR12) rates were 95%-98%. During treatment, improvements in most PRO scores were significant (all but one P < .01) and ranged from, on average, +2.3 to +15.0 points (on a 0-100 scale) by the end of treatment. These improvements were similar between SOF/VEL/VOX and SOF/VEL arms (all P > .05). After treatment discontinuation, patients treated with both regimens achieved significant and clinically meaningful PRO gains (+2.7 to +16.7 by post-treatment week 12, +3.9 to +20.1 by post-treatment week 24; all but one P < .001). Multivariate analysis showed that depression, anxiety and cirrhosis were the most consistent independent predictors of PRO impairment while no association of PROs with the treatment regimen choice was found (all P > .05). CONCLUSIONS: The pan-genotypic regimens with SOF/VEL with or without VOX not only have excellent efficacy and safety, but also significantly positively impact patients' experience both during treatment and after achieving sustained virologic response in DAA-naïve patients with HCV.

Effect of viral suppression on hepatic venous pressure gradient in hepatitis C with cirrhosis and portal hypertension.

Portal hypertension is a predictor of liver-related clinical events and mortality in patients with hepatitis C and cirrhosis. The effect of interferon-free hepatitis C treatment on portal pressure is unknown. Fifty patients with Child-Pugh-Turcotte (CPT) A and B cirrhosis and portal hypertension (hepatic venous pressure gradient [HVPG] >6 mm Hg) were randomized to receive 48 weeks of open-label sofosbuvir plus ribavirin at Day 1 or after a 24-week observation period. The primary endpoint was sustained virologic response 12 weeks after therapy (SVR12) in patients who received ≥1 dose of treatment. Secondary endpoints included changes in HVPG, laboratory parameters, and MELD and CPT scores. A subset of patients was followed 48 weeks posttreatment to determine late changes in HVPG. SVR12 occurred in 72% of patients (33/46). In the 37 patients with paired HVPG measurements at baseline and the end of treatment, mean HVPG decreased by -1.0 (SD 3.97) mm Hg. Nine patients (24%) had ≥20% decreases in HVPG during treatment. Among 39 patients with pretreatment HVPG ≥12 mm Hg, 27 (69%) achieved SVR12. Four of the 33 (12%) patients with baseline HVPG ≥12 mm Hg had HVPG <12 mm Hg at the end of treatment. Of nine patients with pretreatment HVPG ≥12 mm Hg who achieved SVR12 and completed 48 weeks of follow-up, eight (89%) had a ≥20% reduction in HVPG, and three reduced their pressure to <12 mm Hg. Patients with chronic HCV and compensated or decompensated cirrhosis who achieve SVR can have clinically meaningful reductions in HVPG at long-term follow-up. (EudraCT 2012-002457-29).

Baseline HBsAg and HBcrAg titres allow peginterferon-based 'precision medicine' in HBeAg-negative chronic hepatitis B patients.

Quantitative hepatitis B core-related antigen (qHBcrAg) has been proposed as an additional marker to quantitative HBsAg (qHBsAg), for management of chronic hepatitis B. Evaluate baseline combination of qHBsAg and qHBcrAg for identification of patients that could benefit from pegylated interferon-alpha-2a (PegIFN)-based therapy. Sixty-two HBeAg-negative patients treated with PegIFN or PegIFN plus tenofovir disoproxil fumarate (PegIFN+TDF). HBsAg and HBcrAg titres were evaluated at baseline. Thirty patients received PegIFN and 32 PegIFN+TDF. SR was 10 of 30 and 17 of 32 in PegIFN and PegIFN+TDF patients, respectively. Cut-offs determined by maximized Youden's index for identifying patients likely to respond to therapy were as follows: 3.141 log10 IU/mL and 3.450 log10 U/mL for HBsAg and HBcrAg, respectively. At the end of 3 years post-treatment follow-up, HBsAg loss was observed in 7 of 30 and 6 of 32 in PegIFN and PegIFN+TDF patients, respectively. The AUC was estimated to be 0.716 (95% CI [0.578, 0.855]) for HBsAg and 0.668 (95% CI [0.524, 0.811]) for HBcrAg (P=.5541). PPVs for AUCs(95%CI) were 0.762(0.590-0.947), 0.714(0.533-1.000) and 0.800(0.611-1.000), and NPVs for AUCs(95%CI) were 0.756(0.660-0.899), 0.718(0.630-0.857) and 0.765(0.675-0.889) for qHBsAg, qHBcrAg and the combination of both markers, respectively. Baseline qHBsAg 3.141 log10 IU/mL and qHBcrAg 3.450 log10 U/mL thresholds used separately or in combination allow prediction of response, prior to PegIFN-based therapy, with a PPV of 80.3% and NPV of 76.5%. Baseline qHBsAg is predictive of HBsAg loss. Both markers could be used, separately or in combination, for PegIFN-based 'precision therapy'. Our results emphasize that the combination of PegIFN alpha-2a plus TDF with 53% of SR might be an alternative to finite therapy.

Open-label study of faldaprevir plus peginterferon and ribavirin in hepatitis C virus genotype 1-infected patients who failed placebo plus peginterferon and ribavirin.

Faldaprevir, a hepatitis C virus (HCV) NS3/4A protease inhibitor, was evaluated in HCV genotype 1-infected patients who failed peginterferon and ribavirin (PegIFN/RBV) treatment during one of three prior faldaprevir trials. Patients who received placebo plus PegIFN/RBV and had virological failure during a prior trial were enrolled and treated in two cohorts: prior relapsers (n = 43) and prior nonresponders (null responders, partial responders and patients with breakthrough; n = 75). Both cohorts received faldaprevir 240 mg once daily plus PegIFN/RBV for 24 weeks. Prior relapsers with early treatment success (ETS; HCV RNA <25 IU/mL detectable or undetectable at week 4 and <25 IU/mL undetectable at week 8) stopped treatment at week 24. Others received PegIFN/RBV through week 48. The primary efficacy endpoint was sustained virological response (HCV RNA <25 IU/mL undetectable) 12 weeks post treatment (SVR12). More prior nonresponders than prior relapsers had baseline HCV RNA ≥ 800,000 IU/mL (80% vs 58%) and a non-CC IL28B genotype (91% vs 70%). Rates of SVR12 (95% CI) were 95.3% (89.1, 100.0) among prior relapsers and 54.7% (43.4, 65.9) among prior nonresponders; corresponding ETS rates were 97.7% and 65.3%. Adverse events led to faldaprevir discontinuations in 3% of patients. The most common Division of AIDS Grade ≥ 2 adverse events were anaemia (13%), nausea (10%) and hyperbilirubinaemia (9%). In conclusion, faldaprevir plus PegIFN/RBV achieved clinically meaningful SVR12 rates in patients who failed PegIFN/RBV in a prior trial, with response rates higher among prior relapsers than among prior nonresponders. The adverse event profile was consistent with the known safety profile of faldaprevir.

A Model-Based Illustrative Exploratory Approach to Optimize the Dosing of Peg-IFN/RBV in Cirrhotic Hepatitis C Patients Treated With Triple Therapy.

Hézode et al. recently reported the frequent occurrence of anemia and thrombocytopenia in the ANRS-CO20-CUPIC cohort of hepatitis C virus (HCV) cirrhotic experienced patients treated with pegylated-interferon (Peg-IFN), ribavirin (RBV), and telaprevir or boceprevir.1,2 Using frequent measurements of serum drug concentrations, hemoglobin, and platelet concentrations obtained in 15 patients of this cohort, we show how an on-treatment model-based approach could be used to individualize dose regimen and avoid the occurrence of RBV-induced anemia and Peg-IFN-induced thrombocytopenia.

IFNL3 (IL28B) polymorphism does not predict long-term response to interferon therapy in HBeAg-positive chronic hepatitis B patients.

UNLABELLED: The impact of IFNL3 (IL28B) polymorphism on response to interferon (IFN) treatment in patients infected with hepatitis B virus (HBV) is controversial. We aimed to investigate whether IFNL3 polymorphism (rs12979860) influences the long-term response of chronic hepatitis B (CHB) treatment to conventional IFN. DESIGN: Ninety-seven HBeAg-positive patients treated with IFN were evaluated in this study. Associations were investigated between IFNL3 genotypes and (i) HBeAg seroconversion at the end of treatment (EOT), (ii) sustained virological response (SVR) and (iii) HBsAg seroconversion through long-term follow-up (LTFU). Patients were followed for a median of 14 years. The majority of patients were infected with HBV genotype A (69.6%) and were Caucasian (77.9%). Ninety-five patients were genotyped at rs12979860. Similar IFNL3 distribution was observed among the different ethnicities (P = 0.62) or across HBV genotypes A through G (P = 0.70). Thirty-six patients experienced HBeAg seroconversion at EOT; HBeAg seroconversion rates were 37.0 and 35.5% in patients with CC and CT/TT genotypes, respectively (P = 0.82). Among the 44 patients (45%) who achieved a SVR, SVR rates were 48.9 and 39.6% in patients with CC and CT/TT IL28B genotypes, respectively (P = 0.80). HBsAg seroconversion occurred through LTFU in 28 patients. HBsAg seroconversion rates were 25.5 and 31.2% in patients with CC and CT/TT genotypes, respectively (P = 0.51). No significant relationship between IFNL3 rs12979860 and fibrosis stage was observed (P = 0.85). IFNL3 genotype was neither associated with SVR, nor with HBeAg seroconversion and long-term HBsAg seroconversion in HBeAg-positive CHB patients responding to IFN therapy.

Gene expression and hepatitis C virus infection.

Hepatitis C virus (HCV) is a major cause of chronic liver disease, with about 170 million people infected worldwide. Up to 70% of patients will have persistent infection after inoculation, making this disease a significant cause of morbidity and mortality. The severity of disease varies widely, from asymptomatic chronic infection to cirrhosis and hepatocellular carcinoma. Since the discovery of HCV, the treatment of hepatitis C has considerably improved. Recently, combination of pegylated interferons with ribavirin gives a response rate of about 55%. Treatment is indicated in patients with moderate or severe fibrosis. The tolerability of combination treatment is relatively poor, with a frequent flu-like syndrome and an impaired quality of life. In addition to viral and environmental behavioural factors, host genetic diversity is believed to contribute to the spectrum of clinical outcomes in HCV infection. The sequencing of the human genome, together with the development of high-throughput technologies that measure the function of the genome, have afforded unique opportunities to develop profiles that can distinguish, identify and classify discrete subsets of disease, predict the disease outcome or predict the response to treatment. This paper reviews the published literature on gene expression associated with HCV infection (HCV infection, fibrosis progression), and also according to response to treatment.

[Treatment of chronic hepatitis B]. / Traitement de l'hépatite chronique B.

SUMMARY: In recent years, marked progress has been made in the treatment of chronic hepatitis B. Several agents have been approved: interferon alpha-(IFN), pegylated interferon alpha2a (PEG-IFN alpha2a), lamivudine, adefovir, entecavir, telbivudine and recently, tenofovir. Each drug has advantages and limitations. IFN and PEG-IFN alpha2a have the advantage of inducing a sustained virologic response after a defined, limited course of treatment. However, these drugs are only effective in a minority of patients and have frequent side effects. Analogues have the advantage of being administered orally, with good safety profiles and a potent antiviral effect. However, these drugs need to be administered indefinitely since withdrawal of therapy is generally associated with reactivation, and a sustained response is uncommon except in HBeAg positive patients who develop HBe seroconversion. In case of HBe seroconversion, therapy should usually be continued for at least another 24 weeks. The efficacy of lamivudine is limited by the emergence of lamivudine-resistant HBV. Adefovir is associated with a moderate incidence of resistance but its antiviral effect is not optimal. Entecavir has shown to be more effective with a favourable safety profile and a low incidence of resistance. Telbivudine is more potent and has a lower rate of resistance than lamivudine but the resistance rate is significantly higher than other approved drugs. Tenofovir has a potent antiviral effect with a good resistance profile. The future of chronic hepatitis B therapy appears to be different drug combinations. Normally the advantage of drug combinations versus monotherapy should be additive or synergistic antiviral effects and a decrease in viral resistance. Unfortunately, there are few data available and none of the evaluated analogue combinations have been shown to be better than monotherapy. The only combination which has shown a synergistic effect is of pegylated interferon alpha2a with lamivudine. Therefore, combinations of pegylated interferon with the most potent analogues need to be evaluated. The ultimate goal of therapy is HBsAg seroconversion which is more often observed with interferon. Indeed, quantification of serum HBsAg will be a useful tool to predict the treatment outcome. More potent drugs and new combinations as well as understanding the mechanisms of viral resistance should be evaluated to improve the efficacy of treatment.

Liver gene expression signature to predict response to pegylated interferon plus ribavirin combination therapy in patients with chronic hepatitis C.

BACKGROUND AND AIMS: The gold standard treatment of chronic hepatitis C (CHC) is combined pegylated interferon and ribavirin. Considering side effects and treatment cost, prediction of treatment response before therapy is important. The aim of this study was to identify a liver gene signature to predict sustained virological response in patients with CHC. METHODS: Group A (training set) comprised 40 patients with CHC including 14 non-responders (NRs) and 26 sustained virological responders (SVRs). Group B (validation set) comprised 29 patients including 9 NRs and 20 SVRs. Eleven responder-relapsers were also included. A total of 58 genes associated with liver gene expression dysregulation during CHC were selected from the literature. Real-time quantitative RT-PCR assays were used to analyse the mRNA expression of these 58 selected genes in liver biopsy specimens taken from the patients before treatment. RESULTS: From the Group A data, three genes whose expression was significantly increased in NRs compared with SVRs were identified: IFI-6-16/G1P3, IFI27 and ISG15/G1P2. These three genes also showed significant differences in their expression profiles between NRs and SVRs in the independent sample (Group B). Supervised class prediction analysis identified a two-gene (IFI27 and CXCL9) signature, which accurately predicted treatment response in 79.3% (23/29) of patients from the validation set (Group B), with a predictive accuracy of 100% (9/9) and of 70% (14/20) in NRs and SVRs, respectively. The expression profiles of responder-relapsers did not differ significantly from those of NRs and SVRs, and 73% (8/11) of them were predicted as SVRs with the two-gene classifier. CONCLUSION: NRs and SVRs have different liver gene expression profiles before treatment. The most notable changes occurred mainly in interferon-stimulated genes. Treatment response could be predicted with a two-gene signature (IFI27 and CXCL9).

Chronic hepatitis C: viral clearance several months after discontinuation of therapy in two non-responders.

When hepatitis C virus (HCV) infection becomes chronic, spontaneous viral eradication is a rare event. We report two patients with chronic hepatitis C, non-responders to standard interferon alone. They were treated with Pegylated interferon plus ribavirin. At the end of therapy, HCV RNA was still detectable. Several months after stopping treatment, aminotransferase level normalized and HCV RNA became undetectable. No case of sustained viral response happening several months after therapy has been yet described. During long-term follow-up of non-responders, when a persistent normalization of aminotransferase level is observed after stopping treatment, viral clearance could be suspected.

Management of chronic hepatitis C.

Chronic hepatitis C is a major cause of cirrhosis and primary liver cancer (hepatocellular carcinoma). Decompensated cirrhosis or hepatocellular carcinoma secondary to hepatitis C is the first cause of liver transplantation in Europe and in the United States. The prognosis of chronic hepatitis C depends on the progression of fibrosis which determines the risk of developing cirrhosis and its complications. Knowledge of the natural history and the factors associated with the progression of fibrosis is essential for the patient's management. The risk of the progression of fibrosis is difficult to predict in one particular patient. Liver biopsy remains the best test to evaluate the severity of fibrosis, determine its prognosis and discuss the therapeutic options. At present, in a patient with hepatitis C, combined therapy associating pegylated alpha interferon and ribavirin results in a sustained response in approximately 55% of cases. Based on existing results, the sustained virological response with this treatment option appears to be long lasting, to be associated with a histological benefit and is also probably associated with a reduction in the risk of cirrhosis and hepatocellular carcinoma. The management of hepatitis C virus infections must include better knowledge of the natural history of the disease and existing available antiviral treatments (pegylated interferon and ribavirin) as well as in depth knowledge of the aims of treatment, the results obtained, the predictive factors of response and side effects. With close follow-up, doses can be rapidly modified and erythropoietin more frequently administered; new molecules may also be developed in this context. This paper will discuss the natural history, the factors associated with the progression of fibrosis, the predictive factors of response to treatment, and existing and future treatments for hepatitis C.

Medical therapy of patients affected by HBeAg-negative chronic hepatitis B.

Five agents are currently approved for the treatment of chronic hepatitis B: standard interferon-alpha (IFN-alpha), pegylated interferon-alpha 2a (PEG-IFN-alpha 2a), lamivudine, adefovir and entecavir. Each agent has inherent limitations. IFN and PEG-IFN-alpha 2a are effective in a minority of patients and have frequent side effects that limit their tolerability. The efficacy of lamivudine is limited by the emergence of drug-resistant hepatitis B virus (HBV) mutants, restricting its utility as a long-term therapy. Adefovir is well tolerated and associated with a low incidence of resistance but its antiviral effect is not optimal. Entecavir, which has been recently registered, has a more potent anti-viral effect but its long term efficacy and resistance profile is still not known. These antivirals induce a sustained response after withdrawal of therapy in only a minority of patients and therefore the treatment needs to be indefinitely administered in the majority of patients. After a brief summary of the natural history of chronic hepatitis B in order to understand the indications and the objectives of therapy, this review focuses on treatment of HBeAg-negative chronic hepatitis B with IFN and PEG-IFN-alpha 2a.

Steatosis in chronic hepatitis C: why does it really matter?

Hepatic steatosis is a common histological feature of chronic hepatitis C. Various factors are associated with hepatic steatosis, including obesity, high alcohol consumption, diabetes type II, and hyperlipidaemia. These factors may contribute to steatosis in patients with chronic hepatitis C. In humans, hepatitis C virus (HCV) genotype 3 is more commonly associated with steatosis. In vitro studies and the transgenic mouse model have suggested that the HCV core protein (genotype 1) can induce lipid accumulation within hepatocytes. However, what is the relevance of steatosis in chronic hepatitis C? It seems that in certain populations, steatosis may be associated with fibrosis progression and this may be genotype specific. The mechanisms underlying this association are unknown; neither is it clear whether this holds true for all patients or only a subgroup. Indeed, after antiviral treatment, virus related steatosis disappears whereas the host associated steatosis remains unaffected. This review describes and discusses the basic and clinical aspects of the relationship between steatosis and progression of fibrosis, and response to treatment in patients with chronic hepatitis C.

Treatment of chronic hepatitis C virus in allogeneic bone marrow transplant recipients.

We recently reported an increased incidence of cirrhosis in hepatitis C virus (HCV)-infected stem cell transplant (SCT) recipients. Here, we describe our experience in the treatment of these patients, which has been, to date, poorly reported in the literature. Among 99 HCV-infected HCT recipients, 36 had HCV-related liver lesions on biopsy requiring therapy. Owing to HCV treatment contraindications, only 61% of patients (22/36) could be treated. In all, 12 patients received more than one course of anti-HCV treatment if they had HCV RNA still detectable after the first course of treatment and no treatment contraindications. Combined therapy (pegylated interferon (IFN): n=9, or standard IFN: n=9, in combination with ribavirin) led to sustained virological response in 4/18 (20%) patients as compared to 2/20 (10%) in patients who received IFN alone. Hematological toxicity was more frequent with combined therapy. While anemia responded to erythropoietin and/or dose modification, thrombocytopenia usually led to treatment interruption (n=3). This study thus highlights the efficacy of combined therapy and emphasizes the fact that the undue safety concerns are not a problem when treating this particular population.

Treatment of chronic hepatitis B.

In the last years, marked progress has been made in the treatment of chronic hepatitis B. The efficacy of lamivudine, the first nucleoside analogue available, is limited by the high incidence of resistance. Adefovir, which was recently approved has a comparable efficacy with a very low frequency of resistance. However, adefovir needs to be indefinitely administered as withdrawal of therapy is generally associated with reactivation and sustained response is uncommon. Recent large randomized controlled trials showed that PEG IFNs induce relatively high sustained response rates both in HBeAg positive and HBeAg negative chronic hepatitis B. So far, the combination of PEG IFN with lamivudine, used simultaneously, is disappointing in terms of short-term efficacy. However, long-term efficacy needs to be assessed and different schedules of combination (for example sequential) need to be evaluated. A number of nucleoside analogues, with favourable toxicity profiles and a promise of increased effectiveness against HBV, are at various stages of clinical development. Results of phase III trials of entecavir and emtricitabine confirmed their efficacy. However, while entecavir is associated with a low incidences of resistance, emtricitabine is associated with a relatively high incidence of resistance which limits its use as a monotherapy. The efficacy and safety of new and more potent drugs like telbivudine and clevudine need to be confirmed. The future of chronic hepatitis B therapy seems to be in the combination of different drugs. Ideally, the optimal drugs to combine would meet the following criteria: they should have different sites of action on HBV DNA replication, a potent antiviral effect, an excellent safety profile and they should induce a sustained response with a limited duration of therapy. Indeed, the concept of combination therapy has been recently developed in order to increase efficacy and to decrease the occurrence of viral resistance. However, so far few combinations have been evaluated. No combination therapy demonstrated a benefit as compared with monotherapy. More potent drugs and new combinations together with the understanding of the mechanisms of resistance to therapy are important challenges to improve the efficacy of treatment and decrease in the future the global burden related to chronic hepatitis B.

Treatment of chronic hepatitis c.

Since the discovering of the hepatitis C virus in 1989, the treatment of hepatitis C has considerably improved. Initially, with interferon alpha used as a single drug, the sustained virological response rate was below 20%. Then, with the use of combination therapy of interferon a with ribavirin, the response rate increased to 41%. More recently, combination of pegylated interferons with ribavirin give a response rate of about 54-63%. The long-term follow-up studies showed that sustained virological response is generally associated with clinical and histological improvement. The indication of therapy is mainly based on the results of the liver biopsy which is the best way to assess the prognosis of the liver disease. Therefore, treatment is indicated in patients with moderate or severe necroinflammation or fibrosis. The tolerability of combination therapy is relatively poor with a frequent flu-like syndrome and an impaired quality of life. Factors associated with a poor response to treatment are essentially genotype 1 and high viral load. To further improve the efficacy of therapy, different new drugs are under investigation (amantadine, cytokines). These drugs may be candidates for new combinations. In addition, intensive research is currently done for the development of inhibitors of viral enzymes (helicase, protease or polymerase) and anti-sense oligonucleotides, ribozymes and therapeutic vaccine.