Frequent hepatitis B surface antigen (HBsAg) clearance during tenofovir therapy in persons with HIV/hepatitis B virus coinfection

Introduction: Hepatitis B surface antigen (HBsAg) loss is a rare event among persons with hepatitis B virus (HBV) monoinfection but seems to happen more frequently in people with HIV (PWH). We assessed the proportion of PWH/HBV coinfection who experienced HBsAg loss during long‐term tenofovir‐therapy and evaluated its association with quantitative HBsAg (qHBsAg) levels at tenofovir start. Methods: All Swiss HIV Cohort Study participants with two or more positive HBsAg measurements more than 6 months apart, and at least 4 years of tenofovir‐containing antiretroviral therapy (ART), were considered. Our main outcomes were the loss of HBsAg during the first 2 years of tenofovir therapy and until the last available follow‐up. We explored the association between qHBsAg levels at tenofovir start and HBsAg loss using multivariable logistic regression adjusted for potential confounders. Results: A total of 272 PWH and HBV coinfection were included. Median age was 41 years (IQR 36–46) and 81% (221) were men. At tenofovir start, 62% (169/272) received prior HBV active therapy, 49% (110/224) were hepatitis B e antigen (HBeAg)‐positive, 82% (222/272) had detectable HBV DNA (median 4.0 log10 IU/mL, IQR 2.1–7.5) and 19% (46/242) had low qHBsAg, defined as <1000 IU/mL. HBsAg loss was observed in 7% (19/272) of participants during the first 2 years of tenofovir‐containing ART and in 16% (43/272) after a median follow‐up time of 8.4 years (IQR 2.6–15.8). At the last follow‐up, 59% (16/27) of those with HBsAg loss had seroconverted for detectable anti‐HBs antibodies. In multivariable analyses, low qHBsAg at tenofovir start (OR 5.3, 95% CI 1.6–17.8) was a significant predictor of HBsAg loss. Conclusion: We found high rates of HBsAg loss in PWH and HBV coinfection on long‐term tenofovir‐containing ART, most of whom had low qHBsAg at tenofovir start.