Conditions: Chronic Hepatitis B
Keywords: Hepatitis B Children Pediatric Adefovir Dipivoxil
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 173
Healthy volunteers: no

Brief summary:
The purpose of this study is to investigate the efficacy and safety of adefovir dipivoxil for the treatment of chronic hepatitis B in children and adolescents (age 2 to less than 18 years) following 48 weeks of placebo-controlled, double-blind treatment and following an additional 192 weeks of open-label adefovir dipivoxil treatment.

Detailed description:
Weeks 1 through 48 (Study Year 1): The first 48 weeks of the study were a randomized, double-blind, placebo-controlled, parallel-group treatment period. Participants were randomly assigned to treatment in a 2:1 fashion to ADV or PLB. Prior to randomization, eligible participants were classified into 1 of 6 strata based upon age at screening (2 to \< 7 years; \>= 7 to \< 12 years; \>= 12 to \< 18 years) and prior exposure to treatment for chronic hepatitis B (CHB) (prior treatment; no prior treatment).

Weeks 49 through 240 (Study Years 2 through 5): At Week 48, all placebo-treated participants who did not exhibit HBeAg or hepatitis B surface antigen (HBsAg) seroconversion at Week 44, plus all ADV-treated participants, were offered the opportunity to receive open-label ADV for up to an additional 192 weeks. Any participant with HBV DNA \>= 1000 copies/mL at 2 consecutive visits 12 weeks apart was to be discontinued from open-label study treatment. The only exception was for participants in the adolescent age range with prior lamivudine experience who were allowed the opportunity to add lamivudine to ADV; similarly, if combination failed to impart suppression of HBV DNA below 1000 copies/mL (confirmed) discontinuation was necessary. All participants who discontinued study drug due to confirmed seroconversion were requested to continue to return for study visits for the remainder of the study in order to evaluate the durability of seroconversion. Participants who wished to discontinue study treatment and withdraw from the study prior to study completion were requested to return every 4 weeks for 16 weeks for posttreatment evaluations following an early termination visit. Any participants who experienced posttreatment hepatic flares during the 16-week follow-up period were to be followed every 4 weeks until their ALT levels returned to \<= 2 times the upper limit of normal (ULN) for a maximum off-treatment follow-up of 6 months. Participants who experienced a severe hepatic flare (per protocol definition) after discontinuation of ADV during the open-label treatment period may have been eligible to receive ADV for treatment of the hepatic flare (after consultation with the Gilead medical monitor).

Arms:
arm 1: Participants randomized to receive placebo received placebo during the first 48 weeks of treatment (double-blind phase) and then all eligible participants were administered open-label ADV for the remainder of the study. arm 2: Participants randomized to receive ADV received ADV during the first 48 weeks of treatment (double-blind phase) and then all eligible participants were administered open-label ADV for the remainder of the study.

Interventions: intervention 1: Placebo (PLB) intervention 2: Adefovir Dipivoxil (ADV) intervention 3: Lamivudine
Intervention descriptions: intervention 1: Matching placebo intervention 2: 10-mg tablet or 2-mg/mL oral suspension intervention 3: 100-mg tablet administered according to package labeling. Lamivudine was to be added to the open-label ADV regimen of subjects with a serum HBV DNA concentration \>= 1000 copies/mL at 2 consecutive study visits at or after Study Week 96. If the HBV DNA concentration remained \>= 1000 copies/mL at 2 consecutive study visits after the addition of lamivudine, the investigator was required to discontinue all study drugs, perform the early termination ssessments, and have the subject return every 4 weeks for 16 weeks of posttreatment evaluations.

Protocol document: