Spontaneous remission of hepatitis B virus reactivation during direct‐acting antiviral agent‐based therapy for chronic hepatitis C

The administration of direct-acting antiviral agents (DAAs) to treat hepatitis C virus (HCV) infection has been reported to cause hepatitis B virus (HBV) reactivation. However, the actual conditions of HBV reactivation and the ideal timing of medical intervention have not been fully evaluated. We report the cases of two female patients dually infected with HBV and HCV. Both patients were inactive HBV carriers. Although the serum HCV RNA levels promptly decreased after the initiation of DAA-based therapy, the serum HBV DNA levels gradually increased during DAA-based therapy, with the peak serum HBV DNA levels observed at 16 weeks after the initiation of DAA-based therapy in both cases. Subsequently, we checked the serum HBV DNA levels closely every week several times. Fortunately, the serum HBV DNA levels gradually decreased without medical intervention. Neither case developed an alanine aminotransferase flare-up. The HCV genotypes were 2a and 1b, and the DAA-based therapies of Cases 1 and 2 were 12 weeks of sofosbuvir/ribavirin and ombitasvir/paritaprevir/ritonavir, respectively. The significance of our case reports is the demonstration of the existence of spontaneous remission of HBV reactivation that developed during DAA-based therapy, the avoidance of intervention of nucleot(s)ide analogs by frequent monitoring of serum HBV DNA levels, and development of HBV reactivation regardless of the viral genotype or class of DAA. In conclusion, the close monitoring of serum HBV DNA levels during and after DAA-based therapy is essential and medical intervention for HBV reactivation should be carefully considered on an individual basis.