Hepatitis B-related outcomes following direct-acting antiviral therapy in Taiwanese patients with chronic HBV/HCV co-infection

Background & aims: The outcome of HBV infection, including the dynamics of HBsAg and HBV virological reactivation, among patients coinfected with HCV receiving direct-acting antivirals (DAAs) remains unclear. Thus, we aimed to analyze HBV-related outcomes in these patients.
Methods: Serial HBsAg and HBV DNA levels were measured in 79 HBV/HCV-coinfected patients receiving DAAs (13 receiving anti-HBV nucleot(s)ide analog [NUC] therapy simultaneously). The endpoints included HBsAg dynamics and seroclearance, HBV reactivation (HBV DNA >1 log increase or >100 IU/ml if undetectable at baseline) and HBV-related clinical reactivation.
Results: HBsAg levels declined from a median of 73.3 IU/ml at baseline to 16.2 IU/ml at the end-of-DAA treatment and increased to 94.1 IU/ml at 12 months post-treatment. During a mean 11.1-months of follow-up, 8 (10.1%) patients experienced HBsAg seroclearance and 30 (38.0%) HBV reactivation (12-month cumulative incidence, 10.3% and 40.4%, respectively). Patients with pre-treatment HBsAg ≤10 IU/ml had a significantly higher rate of HBsAg seroclearance (hazard ratio [HR] 8.52; 95% CI 1.048-69.312) and lower risk of HBV reactivation than those with pre-treatment HBsAg >10 IU/ml (HR 2.88; 95% CI 1.057-7.844) in multivariate analyses. Six patients (4 cirrhotics) not receiving NUC therapy experienced HBV-related clinical reactivation; 3 of the 4 cirrhotics developed liver failure and 2 died despite immediate NUC therapy. Compared to untreated HBV-monoinfected patients, HBV/HCV-coinfected patients without NUC prophylaxis had a similar rate of HBsAg seroclearance, but a significantly higher risk of HBV reactivation following DAA therapy (HR 6.59; 95% CI 2.488-17.432).
Conclusions: DAA-treated HBV/HCV-coinfected patients had significantly higher rates of HBV seroclearance, particularly among those with low pre-treatment HBsAg titer, but were at higher risk of HBV reactivation, particularly among those with higher pre-treatment HBsAg titer. Prophylactic anti-HBV therapy is essential for cirrhotic patients, irrespective of baseline HBV DNA levels.
Lay summary: We studied outcomes relating to hepatitis B virus (HBV) in patients coinfected with both hepatitis B and C. Patients receiving direct-acting antiviral treatment for hepatitis C were more likely to experience seroclearance (or functional cure of HBV), but were also more likely to experience HBV reactivation, which can lead to hepatitis, liver failure and death. In coinfected cirrhotic patients being treated for HCV, prophylactic treatment for HBV is mandatory.