High titers of anti-HBs prevent rituximab-related viral reactivation in resolved hepatitis B patient with non-Hodgkin's lymphoma.

Rituximab, an anti-CD20 monoclonal antibody, is associated with an increased risk of hepatitis B virus (HBV) reactivation. This study aimed to determine the predictive factors for rituximab-related HBV reactivation in resolved hepatitis B patients, defined as HBsAg-negative, anti-HBc-positive, and undetectable HBV DNA. Among 840 consecutive patients with CD20-positive B-cell lymphoma who received rituximab-based chemotherapy from 2003 through 2014 at Seoul National University Hospital, 732 patients were excluded because either anti-HBc was not assessed or they were HBsAg-seropositive. This retrospective study included 108 resolved hepatitis B patients. During a median 33.5-month follow-up period, eight cases of HBV reactivation occurred only among the patients with low anti-HBs titers (<100 mIU/ml) at baseline and those who did not receive antiviral prophylaxis. Using multivariate analyses, antiviral prophylaxis and baseline anti-HBs titers were the protective factors for HBV reactivation (hazard ratio [HR], 0.90 and 0.95, respectively). Among those who did not receive antiviral prophylaxis, patients with high baseline anti-HBs (≥100 mIU/ml) experienced significantly lower risk of HBV reactivation (HR, 0.49; P = 0.006) than the patients with low baseline anti-HBs (<100 mIU/ml) whose cumulative HBV reactivation rates at 6 and 24 months after chemotherapy were 8.3% and 17.3%, respectively. High anti-HBs titer at baseline and antiviral prophylaxis prevented HBV reactivation, suggesting antiviral prophylaxis should be considered according to baseline anti-HBs titer. Meticulous follow-up for ALT and HBV DNA without antiviral prophylaxis might be possible for the patients with high baseline anti-HBs (≥100 mIU/ml).