Quantification of HBsAg in nucleos(t)ide-naïve patients treated for chronic hepatitis B with entecavir with or without tenofovir in the BE-LOW study.

Serum hepatitis B surface antigen (HBsAg) levels may predict treatment response in chronic hepatitis B (CHB). We examined the association between changes in HBsAg levels and response to treatment in the BE-LOW study.In this open-label, multicentre study, 379 nucleos(t)ide-naïve patients with hepatitis B e antigen (HBeAg)-positive or -negative CHB were randomized and treated with daily entecavir 0.5mg alone (n = 182) or combined with tenofovir 300 mg (n = 197) for 100 weeks. HBsAg levels were quantified (Abbott Architect assay) at baseline and at Weeks 12, 48, and 96.Mean baseline HBsAg levels were comparable across subgroups by baseline alanine aminotransferase (ALT), genotype, age, and treatment type, but were higher in HBeAg-positive than in HBeAg-negative patients. Mean HBsAg changes from baseline at Weeks 12, 48, and 96 were more pronounced in HBeAg-positive than in HBeAg-negative patients, in patients with genotype A than in those with genotypes C or D, and in patients with elevated baseline ALT, but were similar between treatment groups and between patients of different age categories. Mean HBsAg changes over 96 weeks were also comparable in patients with or without HBV DNA <50 IU/ml at Week 96, but among patients that were HBeAg-positive at baseline, changes were greater for those with Week 96 HBeAg loss than for those without.In this population of HBeAg-positive and HBeAg-negative, nucleos(t)ide-naïve patients, a greater HBsAg decline through 96 treatment weeks was observed in HBeAg-positive patients, especially in those who achieved subsequent HBeAg loss.