We previously reported that 48 weeks of combination therapy with pegylated interferon-α2b (PEG-IFN-α2b) and adefovir dipivoxil (ADV) in patients with chronic hepatitis B led to marked decreases of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) (-2.4 log₁₀ copies/ml). Combination therapy was followed by 96 weeks of ADV monotherapy.

Here, we report on the final outcome after 144 weeks of sequential antiviral treatment. Twenty-four patients were analysed, triplet liver biopsies (taken at baseline, week 48 and week 144) were available from 16 patients.

At week 144, 12/15 patients positive for hepatitis B virus e antigen (HBeAg) had lost HBeAg, alanine transaminase (ALT) levels were normal in 23 patients (96%), median serum HBV DNA had decreased by -4.9 log₁₀ copies/ml and was undetectable (<100 copies/ml) in 11/24 individuals (46%). Median total intrahepatic HBV DNA had decreased by -2.2 log. Although no further significant cccDNA changes occurred between week 48 and week 144, two years of ADV monotherapy proved capable of controlling cccDNA levels in most patients. Analysis of intrahepatic HBV DNA species demonstrated that combination therapy with PEG-IFN-α2b and ADV inhibited viral productivity by 99% and subsequent ADV monotherapy by 76%, respectively. Virus suppression to undetectability within the first 12 weeks of treatment was strongly associated with long-term virological response and HBeAg and hepatitis B virus surface antigen HBsAg seroconversion. Histological improvement was determined in 11/16 patients at week 144. Two patients developed ADV resistance during the third year of treatment.

Reduction of intrahepatic viral load achieved after 48 weeks of combination therapy with PEG-IFN-α2b and ADV was maintained in the following 96 weeks of ADV monotherapy and translated into long-term clinical benefit for most of the treated patients.