Hepatitis B surface antigen declines and clearance during long-term tenofovir therapy in patients coinfected with HBV and HIV.

Background: The kinetics of hepatitis B surface antigen (HBsAg) are predictive in HBV-infected patients treated with pegylated interferon. Knowledge about the value of HBsAg levels in patients coinfected with HBV and human immunodeficiency virus (HIV) is lacking.
Methods: We quantified serum HBsAg in a Dutch multicenter cohort of 104 patients coinfected with HIV and HBV who were treated with tenofovir disoproxil fumarate (TDF) as part of highly active antiretroviral therapy. The median duration of therapy was 57 months (interquartile range, 34-72 months).
Results: Hepatitis B e antigen (HBeAg)-positive patients achieved a decline of 2.2 log IU/mL in HBsAg, whereas HBeAg-negative patients only achieved a decline of 0.6 log IU/mL during 6 years of TDF therapy. Declines in HBsAg at months 6 and 12 correlated with CD4 cell count for HBeAg-positive patients. Five HBeAg-positive patients (8%) and 3 HBeAg-negative patients (8%) cleared HBsAg. HBeAg-negative patients who cleared HBsAg had lower baseline HBsAg as compared to patients who remained HBsAg positive. The majority of patients who cleared HBsAg achieved this end point within the first year. In HBeAg-positive patients, decline in HBsAg at month 6 was predictive of achieving HBsAg seroclearance.
Conclusions: Receipt of TDF therapy by HIV/HBV-coinfected patients for up to 6 years led to a significant decrease in HBsAg in the HBeAg-positive population. HBsAg kinetics early during treatment were predictive of HBsAg seroclearance and correlated with an increased CD4 cell count, underlining the importance of immune restoration in HBV clearance.