RESUMEN
AIM: To compare additive efficacy of combination therapy including interferon (IFN)-alpha2a+lamivudine (3TC) to IFN-alpha2b+3TC in children with chronic hepatitis B virus (HBV) infection. MATERIAL AND METHODS: Chronic hepatitis B infection was determined by presence of HBsAg, HBeAg and HBV DNA in serum screened at 3 months intervals for at least 1 year, serum alanine transaminase (ALT) levels more than 1.5-times the upper normal limit and chronic hepatitis with histological activity index (HAI) more than 6 by liver biopsy. Sixty-three children with chronic hepatitis B infection were treated randomly with thrice-weekly subcutaneous injections of 5 MU/m2 recombinant IFN-alpha2a (n=29) or recombinant IFN-alpha2b (n=34) with the same dose, intervals for 6 months. Patients also received 3TC (4 mg/kg/day, max 100 mg/day) orally daily combined with IFN and continued for 12 months. End of therapy response was defined as ALT normalization, HBV DNA clearance and HBe/anti-HBe seroconversion. Breakthrough infection was determined as re-emergence of HBV DNA in serum after its clearance. Response rate, incidence of side effects and breakthrough infection were compared between IFN-alpha2a+3TC- and IFN-alpha2b+3TC-treated patients. RESULTS: Response rate was 44.8% (n=13) with IFN-alpha2a+3TC and 47.1% (n=16) with IFN-alpha2b+3TC (P=1.0). No significant difference was found in respect to the DNA clearance (P=0.32), anti-HBe (P=1.0), anti-HBs (P=0.09) seroconversion and response rates (P=1.0) between the groups. Breakthrough infection was detected in 1 (3.4%) case on IFN-alpha2a and none of the cases on IFN-alpha2b (P=0.46). All of the patients experienced flu-like symptoms, malaise and fatigue; however, side effect interfering with therapy was not encountered. CONCLUSION: No significant difference was found in response rates achieved by combination therapies based on IFN-alpha2a and IFN-alpha2b. Clinical efficacy of 3TC and two different IFN subtypes was found similar.