New targets and possible new therapeutic approaches in the chemotherapy of chronic hepatitis B

Targeting Viral cccDNA for Cure of Chronic Hepatitis B

Purpose of Review

Chronic hepatitis B (CHB), caused by hepatitis B virus (HBV), is a major cause of advanced liver disease and hepatocellular carcinoma (HCC) worldwide. HBV replication is characterized by the synthesis of covalently closed circular (ccc) DNA which is not targeted by antiviral nucleos(t)ide analogues (NUCs) the key modality of standard of care. While HBV replication is successfully suppressed in treated patients, they remain at risk for developing HCC. While functional cure, characterized by loss of HBsAg, is the first goal of novel antiviral therapies, curative treatments eliminating cccDNA remain the ultimate goal. This review summarizes recent advances in the discovery and development of novel therapeutic strategies and their impact on cccDNA biology.

Recent Findings

Within the last decade, substantial progress has been made in the understanding of cccDNA biology including the discovery of host dependency factors, epigenetic regulation of cccDNA transcription and immune-mediated degradation. Several approaches targeting cccDNA either in a direct or indirect manner are currently at the stage of discovery, preclinical or early clinical development. Examples include genome-editing approaches, strategies targeting host dependency factors or epigenetic gene regulation, nucleocapsid modulators and immune-mediated degradation.

Summary

While direct-targeting cccDNA strategies are still largely at the preclinical stage of development, capsid assembly modulators and immune-based approaches have reached the clinical phase. Clinical trials are ongoing to assess their efficacy and safety in patients including their impact on viral cccDNA. Combination therapies provide additional opportunities to overcome current limitations of individual approaches.

Protective Effects of Moringa oleifera on HBV Genotypes C and H Transiently Transfected Huh7 Cells

Chronic hepatitis B infection treatment implicates a long-lasting treatment. M. oleifera extracts contain compounds with antiviral, antioxidant, and antifibrotic properties. In this study, the effect of M. oleifera was evaluated in Huh7 cells expressing either HBV genotypes C or H for the antiviral, antifibrotic, anti-inflammatory, and antioxidative responses. Huh7 cells were treated with an aqueous extract of M. oleifera (leaves) at doses of 0, 30, 45, or 60 μg/mL. The replicative virus and TGF-β1, CTGF, CAT, IFN-β1, and pgRNA expressions were measured by real time. HBsAg and IL-6 titers were determined by ELISA. CTGF, TGF-β1, IFN-β1, and pgRNA expressions decreased with M. oleifera treatment irrespective of the HBV genotype. HBsAg secretion in the supernatant of transfected Huh7 cells with both HBV genotypes was decreased regardless of the dose of M. oleifera. Similar effect was observed in proinflammatory cytokine IL-6, which had a tendency to decrease at 24 hours of treatment. Transfection with both HBV genotypes strongly decreased CAT expression, which is retrieved with M. oleifera treatment. M. oleifera treatment reduced fibrosis markers, IL-6, and HBsAg secretion in HBV genotypes C and H. However, at the level of replication, only HBV-DNA genotype C was slightly reduced with this treatment.

Pegylated interferon alfa for chronic hepatitis B: systematic review and meta-analysis

Conventional interferon alfa and nucleos(t)ide analogues, such as lamivudine, are frequently used for chronic hepatitis B (CHB) treatment, but are associated with adverse effects and viral resistance. Here we performed a systematic review and meta-analysis evaluating all studies of pegylated interferon alfa (PEG-IFNα) treatment in hepatitis B e antigen (HBeAg)-positive and HBeAg-negative patients with CHB. We searched electronic databases--PubMed, EMBASE, Cochrane Library and LILACS--for randomized controlled trials evaluating PEG-IFNα therapy between 1999 and September 2014. Virological response was the primary outcome. We identified 14 studies involving 2829 patients. Our analysis revealed that PEG-IFNα + lamivudine combination therapy produced better virological and biochemical responses than PEG-IFNα monotherapy in HBeAg-positive and HBeAg-negative patients at the end of treatment. PEG-IFNα + adefovir dipivoxil achieved better seroconversion rate than PEG-IFNα in HBeAg-positive patients at the end of treatment. The present findings demonstrated a beneficial response rate following PEG-IFNα combination therapy with nucelos(t)ides among HBeAg-positive and HBeAg-negative patients with CHB. Further trials are needed to investigate simultaneous and sequential therapy strategies.

Liver Enzymes in Children with beta-Thalassemia Major: Correlation with Iron Overload and Viral Hepatitis

BACKGROUND:

Beta Thalassemia is the most common chronic hemolytic anemia in Egypt (85.1%) with an estimated carrier rate of 9-10.2%. Injury to the liver, whether acute or chronic, eventually results in an increase in serum concentrations of Alanine transaminase (ALT) and Aspartate transaminase (AST).

AIM:

Evaluating the potentiating effect of iron overload & viral hepatitis infection on the liver enzymes.

PATIENTS AND METHODS:

Eighty (80) thalassemia major patients were studied with respect to liver enzymes, ferritin, transferrin saturation, HBsAg, anti-HCV antibody and HCV-PCR for anti-HCV positive patients.

RESULTS:

Fifty % of the patients were anti-HCV positive and 55% of them were HCV-PCR positive. Patients with elevated ALT and AST levels had significantly higher mean serum ferritin than those with normal levels. Anti-HCV positive patients had higher mean serum ferritin, serum ALT, AST and GGT levels and higher age and duration of blood transfusion than the negative group. HCV-PCR positive patients had higher mean serum ferritin and serum ALT and also higher age and duration of blood transfusion than the negative group.

CONCLUSION:

Iron overload is a main leading cause of elevated liver enzymes, and presence of HCV infection is significantly related to the increased iron overload.

A review of non-nucleoside anti-hepatitis B virus agents

Hepatitis B Virus is the most common cause of chronic liver disease worldwide. Currently approved agents of chronic HBV infection treatment include interferon and nucleoside analogues. However, the side effects of interferon and the viral resistance of nucleoside analogues make the current treatment far from satisfactory. Therefore, new drugs with novel structures and mechanisms are needed. Recently, a number of non-nucleoside HBV inhibitors have been obtained from natural sources or prepared by synthesis/semi-synthesis. Some of them exhibited potent anti-HBV activity with novel mechanisms. These compounds provide useful information for the medicinal chemist to develop novel non-nucleoside compounds as anti-HBV agents.

Adenoviral delivery of recombinant hepatitis B virus expressing foreign antigenic epitopes for immunotherapy of persistent viral infection

We previously reported a proof-of-concept study for curing chronic hepatitis B virus (HBV) infection using a foreign-antigen recombinant HBV (rHBV) as a gene therapy vector. Targeted elimination of wild-type HBV (wtHBV)-infected cells could be achieved by functionally activating an in situ T-cell response against the foreign antigen. However, as chronic HBV infection spreads to all hepatocytes, specific targeting of virus-infected cells is thought to be less critical. It is also feared that rHBV may not induce active immunization in a setting resembling natural infection. For this immunotherapeutic approach to be practically viable, in the present study, we used a recombinant adenovirus (rAd) vector for rHBV delivery. The rAd vector allowed efficient transduction of wtHBV-producing HepG2 cells, with transferred rHBV undergoing dominant viral replication. Progeny rHBV virions proved to be infectious, as demonstrated in primary tupaia hepatocytes. These results greatly expanded the antiviral capacity of the replication-defective rAd/rHBV in wtHBV-infected liver tissue. With prior priming in the periphery, transduction with rAd/rHBV attracted a substantial influx of the foreign-antigen-specific T-effector cells into the liver. Despite the fully activated T-cell response, active expression of rHBV was observed for a prolonged time, which is essential for rHBV to achieve sustained expansion. In a mouse model of HBV persistence established by infection with a recombinant adeno-associated virus carrying the wtHBV genome, rAd/rHBV-based immunotherapy elicited a foreign-antigen-specific T-cell response that triggered effective viral clearance and subsequent seroconversion to HBV. It therefore represents an efficient strategy to overcome immune tolerance, thereby eliminating chronic HBV infection.

IMPORTANCE

Adenovirus-delivered rHBV activated a foreign-antigen-specific T-cell response that abrogated HBV persistence in a mouse model. Our study provides further evidence of the potential of foreign-antigen-based immunotherapy for the treatment of chronic HBV infection.

Transfusion transmitted hepatitis: where do we stand now? A one center study in upper egypt

BACKGROUND

Despite progress made in the prevention of transfusion-transmitted infections (TTI) over the last few years, they continue to be a problem in many parts of the world, particularly in multitransfused patients.

OBJECTIVES

The aim of this study was to estimate the prevalence of hepatitis B virus (HBV), hepatitis C virus (HCV), and to evaluate the screening and vaccination program among our cohort of multitransfused children from Qena, Upper Egypt.

PATIENTS AND METHODS

One-hundred children suffering from diseases requiring repeated blood transfusions were included in the study. They were classified into group 1, which included 67 children with thalassemia, and group 2, which included 33 children with hemophilia. Screening for hepatitis B surface antigen, hepatitis B surface antibody, hepatitis B core antibody and antibody to HCV was done using a second-generation enzyme-linked immunosorbent assay technique.

RESULTS

Only 12% of all patients were either acutely or chronically infected with HBV. 46% were immune due to previous vaccination, whereas 39% of patients were not protected from HBV infection. HCV antibodies were positive in 45% of cases. Seventy-eight patients had a complete hepatitis B vaccination in the form of three doses as documented by birth certificate. Thirty-six patients mentioned history suggestive of hepatitis. The prevalence of the studied hepatitis markers was similar in both the thalassemia and hemophilia groups of children.

CONCLUSIONS

Transfusion-transmitted hepatitis is still a major problem for multitransfused children in Egypt. More effort is required to reduce the infection rate through proper screening of blood and blood products, strict emphasis on receiving the vaccine, regular follow-up for those children with a hepatitis B antibody titer, and providing booster doses for those in need.

Human microRNA hsa-miR-125a-5p interferes with expression of hepatitis B virus surface antigen

MicroRNAs are small non-coding RNAs that modulate gene expression at post-transcriptional level, playing a crucial role in cell differentiation and development. Recently, some reports have shown that a limited number of mammalian microRNAs are also involved in anti-viral defense. In this study, the analysis of the hepatitis B virus (HBV) genome by the computer program MiRanda led to the identification of seven sites that are potential targets for human liver microRNAs. These sites were found to be clustered in a 995-bp segment within the viral polymerase ORF and the overlapping surface antigen ORF, and conserved among the most common HBV subtypes. The HBV genomic targets were then subjected to a validation test based on cultured hepatic cells (HepG2, HuH-7 and PLC/PRF/5) and luciferase reporter genes. In this test, one of the selected microRNAs, hsa-miR-125a-5p, was found to interact with the viral sequence and to suppress the reporter activity markedly. The microRNA was then shown to interfere with the viral translation, down-regulating the expression of the surface antigen. Overall, these results support the emerging concept that some mammalian microRNAs play a role in virus-host interaction. Furthermore, they provide the basis for the development of new strategies for anti-HBV intervention.

Effect of nucleoside analog-interferon sequential therapy on patients with acute exacerbation of chronic hepatitis B

AIM

Nucleoside analog (NA)-interferon (IFN) sequential therapy may enable the long-term control of chronic hepatitis B (CHB) and the withdrawal of the nucleoside analog. We evaluated the efficacy of NA-IFN sequential therapy for acute exacerbation of CHB.

METHODS

A total of 12 patients with acute exacerbation of CHB, nine of whom were positive for hepatitis B e antigen (HBeAg), were enrolled in this study. All the patients were treated with lamivudine 100 mg/day alone for 20 weeks, then with both IFN-alpha 6 megaunits three times per week and lamivudine for 4 weeks, and lastly, with IFN-alpha alone for 20 weeks. Patients whose serum alanine aminotransferase (ALT) level was normalized, whose serum hepatitis B virus (HBV) DNA level decreased to less than 5 log copies/mL, and HBeAg level was absent 24 weeks after the end of treatment were defined as having sustained virological response (SVR). The other patients were defined as having no response (NR).

RESULTS

Four out of nine (44.4%) HBeAg-positive and all three HBeAg-negative patients achieved SVR. The levels of serum alanine aminotransferase (ALT), HBV DNA and HBV core-related antigen were similar between SVR and NR patients at baseline. Three of four patients (75.0%) whose serum HBeAg became negative at the end of treatment achieved SVR, while one of five (20.0%) whose serum HBeAg remained positive achieved SVR.

CONCLUSION

NA-IFN sequential therapy for patients with acute exacerbation of CHB enables the withdrawal of treatment and is particularly effective for patients whose serum HBeAg has become undetectable by the end of the IFN treatment.

Production, characterization and in vitro testing of HBcAg-specific VHH intrabodies

Hepatitis B virus (HBV) infections represent a global health problem, since these account for 350 million chronic infections worldwide that result in 500,000-700,000 deaths each year. Control of viral replication and HBV-related disease and mortality are of utmost importance. Because the currently available antiviral therapies all have major limitations, new strategies to treat chronic HBV infection are eagerly awaited. Six single-domain antibodies (VHHs) targeting the core antigen of HBV (HBcAg) have been generated and three of these bound strongly to HBcAg of both subtype ayw and adw. These three VHHs were studied as intrabodies directed towards the nucleus or the cytoplasm of a hepatoma cell line that was co-transfected with HBV. A speckled staining of HBcAg was observed in the cytoplasm of cells transfected with nucleotropic VHH intrabodies. Moreover, an increased intracellular accumulation of hepatitis B e antigen (HBeAg) and a complete disappearance of intracellular HBcAg signal were observed with nuclear targeted HBcAg-specific VHHs. These results suggest that HBcAg-specific VHHs targeted to the nucleus affect HBcAg and HBeAg expression and trafficking in HBV-transfected hepatocytes.

Four conserved cysteine residues of the hepatitis B virus polymerase are critical for RNA pregenome encapsidation

Hepadnaviruses replicate via reverse transcription of an RNA template, the pregenomic RNA (pgRNA). Although hepadnaviral polymerase (Pol) and retroviral reverse transcriptase are distantly related, some of their features are distinct. In particular, Pol contains two additional N-terminal subdomains, the terminal protein and spacer subdomains. Since much of the spacer subdomain can be deleted without detrimental effects to hepatitis B virus (HBV) replication, this subdomain was previously thought to serve only as a spacer that links the terminal protein and reverse transcriptase subdomains. Unexpectedly, we found that the C terminus of the spacer subdomain is indispensable for the encapsidation of pgRNA. Alanine-scanning mutagenesis revealed that four conserved cysteine residues, three at the C terminus of the spacer subdomain and one at the N terminus of the reverse transcriptase subdomain, are critical for encapsidation. The inability of the mutant Pol proteins to incorporate into nucleocapsid particles, together with other evidence, argued that the four conserved cysteine residues are critical for RNA binding. One implication is that these four cysteine residues might form a putative zinc finger motif. Based on these findings, we speculate that the RNA binding activity of HBV Pol may be mediated by this newly identified putative zinc finger motif.

Correlation of quantitative assay of HBsAg and HBV DNA levels during chronic HBV treatment

BACKGROUND AND AIM

Viral load is used for the diagnosis and monitoring the treatment of chronic hepatitis B (CHB). These methods are molecular-based and are expensive. Previous studies suggest that quantitative hepatitis B surface antigen (HBsAg) studied by automated chemiluminescent microparticle immunoassay can be a surrogate marker. In this study, we aimed to investigate whether quantitative HBsAg correlates hepatitis B virus (HBV) DNA levels during CHB treatment.

METHODS

The study included 18 patients (13 male, 5 female, mean age: 33 +/- 9 years) with CHB. They were given pegylated interferon +/- lamivudine for 52 months and serum samples were obtained in weeks 0, 4, 8, 24, 48, 52, and 76. HBV DNA was measured by TaqMan polymerase chain reaction (PCR; Erasmus MC, University Medical Center, Rotterdam, The Netherlands). Quantitative HBsAg was studied by automated chemiluminescent microparticle immunoassay (Architect HBsAg, Abbott, IL). Results HBV DNA levels were measured as follows: 9.66, 7.69, 7.06, 5.93, 5.89, 5.88, and 7.27 logarithmic genome equivalent/ml, respectively. The corresponding HBsAg quantitation results were 42,888, 31,176, 37,882, 27,277, 28,279, 29,471, and 31,535 IU/ml, respectively. They showed a significant correlation (canonical correlation = 0.85).

CONCLUSIONS

HBsAg studied by automated chemiluminescent microparticle immunoassay correlates with HBV DNA and can be a surrogate marker during the monitoring of the efficacy of HBV treatment.

Isolation of quinic acid derivatives and flavonoids from the aerial parts of Lactuca indica L. and their hepatoprotective activity in vitro

In our continuing study of biologically active compounds from Korean medicinal plants, we investigated the hepatoprotective constituents of the aerial parts of Lactuca indica L. (Compositae), since the methanolic extract of L. indica has hepatoprotective activity against hepatitis B virus (HBV) production. The bioactivity-guided separation of the methanolic extract of the aerial parts of L. indica resulted in the isolation of seven quinic acid derivatives (1, 3-4, 6, and 10-12), along with five flavonoids (2, 5, and 7-9). All the isolated compounds were evaluated for hepatoprotective activity by the HBV assay in vitro. In the human HBV-transfected liver cell line HepG2.2.15, all the compounds except 2 and 5 effectively reduced HBV DNA level in the release of mature HBV particles from HepG2.2.15 cultivation. Of the ten active compounds, treatment with 1, 3, and 12 led to significant reduction in the extracellular HBV DNA level, suggesting that they could be potent phytochemical agents against hepatitis B virus.

Optimized expression from a synthetic gene of an untagged RNase H domain of human hepatitis B virus polymerase which is enzymatically active

The RNase H domain of human hepatitis B virus (HBV) polymerase is an attractive molecular target for the development of new anti-HBV drugs. In this study, a synthetic gene coding for HBV RNase H was assembled from 12 oligonucleotides and expressed in Escherichia coli. The encoded protein was then recovered from inclusion bodies, purified, and refolded by a dilution-dialysis procedure in the presence of a low concentration of lauroylsarcosine (0.01%). The presence of the detergent was an absolute requirement for solubility, suggesting that the untagged RNase H might have exposed hydrophobic regions that need to be shielded from the solvent. The structural identity of the protein was confirmed by N-terminal amino acid sequence analysis and mass spectrometry. The enzymatic activity of HBV RNase H was then tested by a recently developed fluorometric assay and was found to be only slightly lower than that registered with the entire HIV-1 reverse transcriptase. Finally, a structural model of the enzyme showed that H715, R744 and K745 may be involved in substrate recognition.

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Virology of hepatitis B and C viruses and antiviral targets

Hepatitis B and C viruses belong to two distinct virus families, the Hepadnaviridae and the Flaviviridae, respectively, and have different virological characteristics. Better knowledge of their lifecycles and variability offers the opportunity to develop novel therapeutic approaches and classes of drugs. The issue of cccDNA clearance, however, remains in hepatitis B treatment, whereas HCV infection is curable.

Emerging therapeutics for chronic hepatitis B

Hepatitis B is a global health problem. Patients with chronic hepatitis B (CHB) carry a significant risk to eventually develop cirrhotic liver disease. Recent therapeutic advances against CHB offer excellent potential for long-term suppression of hepatitis B virus (HBV) replication during antiviral therapy, and occasionally a durable remission off medication. Selection of appropriate patients for antiviral therapy depends on identification of HBV replication and an elevated alanine aminotransferase level or histologic liver injury. Pegylated interferon alpha offers potent immunomodulatory and antiviral activity with the potential for durability, but also with adverse effects and significant cost. The nucleoside or nucleotide analogs, lamivudine, adefovir, and entecavir, suppress HBV replication and are extremely well-tolerated, but long-term or even lifelong therapy is required. Most experience has been gained with lamivudine, but viral resistance occurs frequently. Newer analogs appear to be relatively free of this problem. Approaches using a combination of agents have promise, but have yet to be proven superior to individual drugs alone.

Fibronectin is essential for hepatitis B virus propagation in vitro: may be a potential cellular target?

Previous studies in our laboratory strongly suggested that fibronectin was upregulated by hepatitis B virus (HBV) in HepG2.2.15 cells. Report by Budkowska A also indicated that human liver fibronectin could bind HBV in a species-restricted manner. Therefore, it is reasonable to ask whether inhibiting fibronectin expression might have anti-HBV activity and whether fibronectin might be developed as a new potential cellular target for anti-HBV drugs. By using fibronectin antisense oligonucleotide (ASODN), fibronectin antibody, and Protocatechuic aldehyde (PA), we were able to show that HBV productions in HepG2.2.15 cell culture were reduced in a dose-dependent manner by fibronectin inhibition. In addition, we found that treatment with ASODNs, fibronectin antibody, and PA did not affect HepG2.2.15 cell viability. Furthermore, we observed that fibronectin inhibition sensitized HBV to anti-HBV drugs. In summary, this study demonstrates that fibronectin is essential for HBV propagation and also provides some evidences for the potential of fibronectin as a new cellular target for HBV infection therapy.

Successful treatment with tenofovir in a child C cirrhotic patient with lamivudine-resistant hepatitis B virus awaiting liver transplantation. Post-transplant results

Antiviral treatment can be complex in decompensated hepatitis B virus (HBV) cirrhosis because of potential emergence of lamivudine-resistant mutants and worsening liver function, and to multifactorial nephrotoxicity. Negative HBV-DNA status by hybridization before liver transplantation is a favorable prognostic factor. We present the case of a 54-year-old HBV+ liver transplantation candidate who, after testing negative for HBV-DNA, developed YMDD lamivudine-resistant mutants resulting in a deteriorated clinical condition. After 8 months of adefovir plus lamivudine double therapy, only partial response was achieved. Tenofovir was added to this regimen, and an early decline of HBV-DNA was seen at 4 weeks without adverse events. The patient underwent transplantation. At 21-month postoperative follow-up, the patient's outcome was excellent. Post-transplantation HBV prophylaxis, taking into account the prior development of mutants, consists of hepatitis B immunoglobulin plus lamivudine and adefovir. Tenofovir was well tolerated and produced a fast antiviral response, suggesting its potential value in combined antiviral treatment for liver transplantation candidates.

Entecavir for the treatment of chronic hepatitis B

Chronic infection with the hepatitis B virus remains a serious and life-threatening disease for approximately 5% of the world's population, despite the availability of effective vaccines. Although prognoses can be improved by chemotherapy, treatment options are limited and none has been consistently successful. Interferon-alpha, the longest established therapy, has limited efficacy, is slow-acting and frequently causes adverse effects. Newer drugs comprise of mainly nucleoside and nucleotide analogs. The two that are currently approved, lamivudine and adefovir dipivoxil, are well tolerated; both produce rapid and dramatic responses, but their effects may not be sustainable in the long-term due to the emergence of resistant virus. Development of resistance to lamivudine is approximately ten-times more frequent than development of resistance to adefovir dipivoxil (approximately 60 and 6%, respectively) during the first 3 years of therapy. Entecavir, a carbocyclic deoxyguanosine analog that is active against both lamivudine- and adefovir dipivoxil-resistant HBV, is in the vanguard of new antihepatitis B virus drugs that have progressed to Phase III clinical trials. It is the most potent antihepatitis B virus agent discovered to date.

Translation of the first upstream ORF in the hepatitis B virus pregenomic RNA modulates translation at the core and polymerase initiation codons

The human hepatitis B virus (HBV) has a compact genome encoding four major overlapping coding regions: the core, polymerase, surface and X. The polymerase initiation codon is preceded by the partially overlapping core and four or more upstream initiation codons. There is evidence that several mechanisms are used to enable the synthesis of the polymerase protein, including leaky scanning and ribosome reinitiation. We have examined the first AUG in the pregenomic RNA, it precedes that of the core. It initiates an uncharacterized short upstream open reading frame (uORF), highly conserved in all HBV subtypes, we designated the C0 ORF. This arrangement suggested that expression of the core and polymerase may be affected by this uORF. Initiation at the C0 ORF was confirmed in reporter constructs in transfected cells. The C0 ORF had an inhibitory role in downstream expression from the core initiation site in HepG2 cells and in vitro, but also stimulated reinitiation at the polymerase start when in an optimal context. Our results indicate that the C0 ORF is a determinant in balancing the synthesis of the core and polymerase proteins.

Pegylated interferon alfa-2b alone or in combination with lamivudine for HBeAg-positive chronic hepatitis B: a randomised trial

BACKGROUND

Treatment of HBeAg-positive patients with chronic hepatitis B is not effective in most. A combination of immunomodulatory pegylated interferon alfa-2b and antiviral lamivudine might improve the rate of sustained response.

METHODS

307 HBeAg-positive patients with chronic hepatitis B were assigned combination therapy (100 microg/week pegylated interferon alfa-2b and 100 mg/day lamivudine) or monotherapy (100 microg/week pegylated interferon alfa-2b and placebo) for 52 weeks. During weeks 32-52 the pegylated interferon dose was 50 microg/week in both treatment groups. The analyses were based on the modified intention-to-treat population after exclusion of 24 patients from one centre withdrawn for misconduct, ten who lost HBeAg before the study start, and seven who received no study medication. All included patients were followed up for 26 weeks after treatment.

FINDINGS

49 (36%) of 136 patients assigned monotherapy and 46 (35%) of 130 assigned combination therapy had lost HBeAg at the end of follow-up (p=0.91). More of the combination-therapy than of the monotherapy group had cleared HBeAg at the end of treatment (57 [44%] vs 40 [29%]; p=0.01) but relapsed during follow-up. Patterns were similar when response was assessed by suppression of serum hepatitis B virus (HBV) DNA or change in concentrations of alanine aminotransferase. Response rates (HBeAg loss) varied by HBV genotype (p=0.01): A, 42 (47%) patients; B, ten (44%); C, 11 (28%); and D, 26 (25%).

INTERPRETATION

Treatment with pegylated interferon alfa-2b is effective for HBeAg-positive chronic hepatitis B. Combination with lamivudine in the regimen used is not superior to monotherapy. HBV genotype is an important predictor of response to treatment.

Treatments for hepatitis B

New optimism surrounds treatments for chronic hepatitis B (CHB). Interferon- alpha , lamivudine, and adefovir dipivoxil are currently approved by the United States Food and Drug Administration for the treatment of CHB. All 3 treatments possess unique characteristics with respect to their side effect profiles, potencies, and treatment niches within the spectrum of CHB. New agents, which are in various stages of clinical development, represent potential improvements within existing, as well as novel, classes of antiviral therapy, and they offer significant promise of a cure for the many patients with chronic and progressive hepatitis B. However, there remain many challenges in understanding the implications of drug resistance, the role of combination therapy, and how to define the response to therapy within subsets of patients with hepatitis B.

Hepatocellular carcinoma: paradigm of preventive oncology

Morbidity and mortality from hepatocellular carcinoma (HCC), which is primarily caused by hepatitis B virus or hepatitis C virus, can be prevented. Public health interventions have eliminated transfusion transmission of these viruses and, in endemic countries with effective hepatitis B virus vaccination programs, have greatly reduced incident hepatitis B virus infections (and HCC) in children. Antiviral treatment can eliminate detectable hepatitis C virus in 50%-80% of chronically infected patients, presumably reducing their risk of cancer. HCC survival rates remain universally poor, but early detection and treatment in developed countries has improved survival in selected patients. Despite these advances, worldwide HCC rates remain high, and additional preventive efforts are needed. The most important opportunity is wider distribution of hepatitis B virus vaccine in endemic areas. Development of an HCV vaccine, improved antiviral therapies, and better methods for HCC detection would also help decrease morbidity and mortality from HCC. HCC prevention efforts provide a paradigm for preventive oncology in cancers of viral etiology.

Antiviral therapy: nucleotide and nucleoside analogs

For the management of HBV infection, an increasing number of nucleotide and nucleoside analogs are active against wild-type HBV and some against HBV with YMDD and other compensatory mutations. Table 2 depicts the IC50 and susceptibilities of HBV to various antiviral agents. The dichotomy between in vitro and in vivo susceptibilities to YMDD mutants is due to a change in IC50 between wild-type and mutant virus. Thus a drug may have less activity in vitro but at doses used in vivo show activity against YMDD and other compensatory mutations. Some HBV drugs share activity against HIV, which may be useful in the co-infected patient. Other nucleoside analogs are in various stages of development, including MCC-478 and DAPD. In the future, clinicians will have a plethora of reagents to chose from, and combination therapies may be invoked.