Monitoring and Treatment of Patients Undergoing Immunotherapy With Anti-CD20 Who are Exposed to HBV.

Reactivation of hepatitis B virus (HBV) is a potentially fatal complication of immunosuppressive therapy, and can occur in individuals who are hepatitis B surface antigen (HBsAg) negative but positive for hepatitis B core antibody (anti-HBc). While anti-HBc positivity indicates prior HBV exposure, it may also reflect clearance of HBsAg, but with viral persistence at low intrahepatic replicative and transcriptional levels. HBV reactivation can still occur during intense immunosuppression, including B cell-depleting therapy with anti-CD20 antibodies and hematopoietic stem cell transplantation. While prevention via antiviral prophylaxis is recommended, it remains uncertain, from a global perspective, if this is an ideal and cost-effective strategy. An alternative is regular HBV DNA monitoring. However, this approach is problematic in resource-constrained regions, where the logistics of sample collection, transportation, and molecular analysis in dedicated facilities poses challenges. We aimed to evaluate the effectiveness of simple monitoring strategies using routine liver biochemistry and serum HBsAg in preventing HBV-related complications during anti-CD20 therapy.