Role of Hepatitis B Surface Antigen in Hepatitis B Virus Relapse After Entecavir or Tenofovir Prophylaxis in Patients Undergoing Cancer Chemotherapy

Background And Aim: This study investigated whether hepatitis B surface antigen (HBsAg) could predict hepatitis B virus (HBV) relapse after cessation of entecavir or tenofovir disoproxil fumarate (TDF) prophylaxis for chronic hepatitis B cancer patients who are undergoing chemotherapy.

Methods: The study enrolled 122 hepatitis B e-antigen-negative cancer patients who underwent chemotherapy with entecavir or TDF for antiviral prophylaxis and posttreatment follow-up for at least 6 months.

Results: Of the 122 patients, 52 and 18 experienced virological and clinical relapse, which had 3-year cumulative incidences of 46.6% and 18.6%, respectively. Multivariate analysis showed that end-of-treatment HBsAg levels and baseline HBV-DNA ≥ 2000 IU/mL were independent predictors of virological relapse. The best HBsAg cutoff value was 500 IU/mL. An end-of-treatment HBsAg of 500 IU/mL was useful for predicting virological relapse in patients with baseline HBV-DNA < 2000 IU/mL (3-year rate: 21.3% vs 46.4%, P = 0.038, in patients with HBsAg < 500 and ≥ 500 IU/mL, respectively), but not in patients with baseline HBV-DNA ≥ 2000 IU/mL. Of the 52 patients who experienced virological relapse, 13 experienced transient virological relapse. Patients with baseline HBV-DNA level < 2000 IU/mL experienced a higher rate of transient virological relapse (42.1% vs 15.2%, P = 0.031). Three patients experienced hepatic decompensation upon alanine aminotransferase flares, and no patient died after timely retreatment. Ten patients experienced posttreatment HBsAg loss, and the 3-year HBsAg loss rate was 30.7% in patients with end-of-treatment HBsAg < 100 IU/mL.

Conclusions: The baseline HBV-DNA and end-of-treatment HBsAg levels could predict virological relapse after withdrawal of entecavir and TDF prophylaxis for chemotherapy.