Forty-eight weeks treatment with clevudine 30 mg qd versus lamivudine 100 mg qd for chronic hepatitis B infection: a double-blind randomized study / 대한간학회지

BACKGROUND/AIMS: Clevudine is a pyrimidine analogue with potent activity against hepatitis B virus (HBV) replication in vitro. In a previous pivotal phase III clinical study, 24 weeks treatment with clevudine 30 mg has been shown to profoundly suppress HBV replication and normalize serum alanine aminotransferase level. METHODS: In this study, we compare the efficacy and safety of clevudine (30 mg daily) versus lamivudine (100 mg daily) for 48 weeks in treatment-naive chronic hepatitis B e antigen (HBeAg) positive patients. RESULTS: Ninety-two chronic HBeAg positive patients were randomized to receive clevudine 30 mg daily or lamivudine 100 mg daily in a 1:1 ratio. The clevudine group demonstrated greater viral suppression at week 48 when compared with the lamivudine group (median reduction: 4.27 vs. 3.17 log(10) copies/ml at week 48, p<0.0001). At week 48, serum HBV DNA level was below 300 copies/mL in 73% and 40% in the clevudine and lamivudine groups, respectively (p=0.001). HBeAg seroconversion occurred in 18% of patients in the clevudine group versus 12% in the lamivudine group at week 48. Lamivudine-resistant mutations were detected in 11 (24%) patients in the lamivudine group, who showed viral rebound during lamivudine therapy but no resistance was found in the clevudine group during 48-week treatment period. CONCLUSIONS: A 48-week dosing with clevudine 30 mg daily was superior to lamivudine 100 mg daily in suppressing HBV replication, with no emergence of viral breakthrough in patients with HBeAg positive chronic hepatits B.

Chronic hepatitis B--treatment with nucleoside analogues

Nucleot(s)ide analogues are making milestones in the treatment of chronic hepatitis B (CHB) as safe oral therapy. FDA approved lamivudine in adult patients in 1998, adefovir dipivoxil in 2002, and entecavir in March 2005. Lamivudine is effective in viral suppression, ALT normalization, and improvement in histology in both HBeAg positive and HBeAg negative / HBV DNA positive patients. HBeAg seroconversion rates correlate directly with pretreatment ALT levels at 18-30% after one year of therapy. Hepatitis flares may occur if lamivudine is stopped before HBeAg seroconversion. Lamivudine resistant YMDD mutants emerge at a rate of 15-20% per year of therapy; often associated with the rebound viraemia, relapse of hepatitis or even hepatic decompensation. Durability of response off lamivudine therapy is not satisfactory and may be dependent on duration of therapy post-seroconversion. Lamivudine is well tolerated with few serious adverse events, even in patients with decompensated cirrhosis. Long term therapy in viraemic patients with advanced fibrosis or cirrhosis delays clinical progression. Adefovir dipivoxil is an oral prodrug of adefovir. 10 mg daily is effective in suppressing both wild-type HBV and YMDD mutants, normalising ALT and improving histology. Adefovir dipivoxil has been shown to be well tolerated in longterm therapy. Renal toxicity reported in higher dosages is rarely seen except among patients with creatinine clearance less than 50 ml/min. Adefovir resistance may emerge and the overall rate is much lower than lamivudine, reaching 18% after 4 years of therapy. Adefovir-resistant mutants (rt N236T) are susceptible to lamivudine and entecavir. Little data is available for durability of response off therapy. Entecavir is an oral nucleoside analogue with a recommended dosage of 0.5 mg daily for nucleoside-naive patients, and 1 mg daily for lamivudine-refractory patients. It is a potent antiviral and may also reduced intrahepatitic cccDNA. Entecavir resistance so far has only been detected in lamivudine resistant patients in the one-year studies. Patient counseling is very important to decide on the choice among available therapeutic options. The assessment of the risks/benefits of each option should be carefully explained to individual patient.

HBV and liver cancer

The association of hepatitis B virus (HBV) infection and liver cancer is well documented in epidemiological study. Patients with chronic hepatitis B have increased risk of hepatocelluar carcinoma (HCC), in particular those with active liver disease and cirrhosis. The incidence of HCC increases with age and is more common among male patients. The introduction of universal HBV vaccination program for the newborn in endemic regions has started to show beneficial impact. Taiwan introduced this program two decades ago and the incidence of liver cancer among infants and young children have declined significantly. The carcinogenic events leading to HCC are under intense research. A number of hypotheses have been proposed. HBV is not directly hepatotoxic but its interaction with the host immune system creates opportunity for HBV DNA integration into the host genome. One of the main foci of research is the HBX-encoded X protein. Its integration and protein expression impose alteration in cell proliferation cycle and apoptosis process. Many other factors may be involved including viral-induced alterations in p53 and telemerase, HBV genotypes, co-infection with HCV or delta agents, patient's lifestyle such as smoking, alcohol excesses, and genetic factors of the host patient. The processes of necroinflammation, cell proliferation and fibrosis facilitate the initial carcinogenic development. HCC surveillance with tumor markers such as alpha-foetal protein, decarboxylated prothrombin, in conjunction with imaging techniques has identified early small HCC that is amenable to curative therapy. Viral load has been correlated with increase risk of HCC. The available anti-viral agents have demonstrated clinical benefit among those with maintained and sustained response. Interferon and lamivudine therapy have demonstrated reduction of HCC among responders. However, they only constitute a minority proportion of treated patients. The mainstay of prevention should lie in prevention of HBV infection and early effective therapy of chronic hepatitis B infection.