Tommy has chronic HBV infection. (Hepatoloty)

While many studies have assessed treatment of chronic hepatitis B virus (HBV) infection in adults, less is known about optimal therapy for children and adolescents.

As reported in the June 2008 issue of Hepatology, M. Jonas of Children's Hospital in Boston and colleagues investigated the safety, efficacy, and pharmacokinetics of adefovir (Hepsera) in 173 treatment-naive and treatment-experienced children and adolescents with hepatitis B "e" antigen (HBeAg) positive chronic hepatitis B.

Study participants were randomly assigned to receive adefovir or placebo. Randomization was stratified by age (2 to < 7 years, >7 to <12 years, and >12 to <18 years) and prior treatment. The primary efficacy endpoint was serum HBV DNA < 1000 copies/mL and normal alanine aminotransferase (ALT).

Results

• Significantly more patients aged 12 to <18 years achieved HBV DNA < 1000 copies/mL and normal ALT in the adefovir arm compared with the placebo arm (23% vs 0%; P = 0.007).

• In the younger age groups, differences between the adefovir and placebo arms at the end of blinded treatment were not statistically significant.

• More adefovir than placebo subjects experienced HBeAg seroconversion (15.9% vs 5.3%; P = 0.051).

• More patients in the adefovir arm achieved the combined endpoint of HBeAg seroconversion, HBV DNA < 1000 copies/mL, and normal ALT (10.6% vs 0; P = 0.009).

• No patients developed adefovir-associated resistance mutations linked to HBV DNA rebound (rtN236T or rtA181V).

• Adefovir plasma concentrations were comparable across groups and within the target range.

• Adefovir was well tolerated and no new safety issues were identified.

• Treatment-related adverse events were reported for 12% of subjects in the adefovir arm and 10% in the placebo arm.

• After 48 weeks of adefovir treatment, antiviral efficacy in HBeAg positive patients aged 12 to <18 years was similar to that observed in a prior study of treatment-naive HBeAg positive adults.

• Adefovir outcomes were not different from placebo in patients aged 2 to 11 years, despite adequate plasma drug exposure in all 3 age groups.