Real-world outcomes of antiviral therapy in Asian chronic HBV patients described
medwireNews: Analysis of a community-based cohort comprising mainly Asian patients receiving antiviral therapy for chronic hepatitis B virus (HBV) infection shows a higher rate of hepatitis B surface antigen (HBsAg) loss than is generally reported for Asian clinical trial cohorts.
And although only a third of the patients with HBsAg loss developed surface antibodies (anti-HBs) during the course of follow-up, nearly all patients achieved and maintained undetectable viral levels, the researchers report.
Robert Wong (Alameda Health System – Highland Hospital, Oakland, California, USA) and co-workers evaluated the outcomes of 1072 chronic HBV patients (98.1% Asian) treated at two US community clinics between 1997 and 2015 for a median duration of 76.7 months, with the majority receiving tenofovir disoproxil fumarate (TDF; 47.8%) or entecavir (46.1%).
As reported in the Journal of Viral Hepatitis, 4.58% of patients achieved HBsAg loss during a median follow-up of 81.6 months, which is notable given that some previous analyses have shown no HBsAg loss in Asian patients despite 3 to 5 years of nucleos(t)ide analog therapy, the team remarks.
Of these 49 patients, 33.3% underwent seroconversion to anti-HBs, 66.0% achieved normalization of alanine aminotransferase levels, and 95.8% achieved and maintained undetectable levels of HBV DNA until the end of follow-up.
Six patients with HBsAg loss, one of whom had also developed anti-HBs, experienced seroreversion, testing positive for the antigen again. But the researchers point out that all six patients had undetectable HBV DNA levels despite the seroreversion, “demonstrating the sustainability of viral suppression.”
Of note, the rates of HBsAg loss, and indeed of the other outcome measures, did not differ significantly between the 68.2% of patients who were negative for the hepatitis B e antigen (HBeAg) at baseline and the remaining 31.8% who were HBeAg-positive. Specifically, HBsAg loss occurred in 4.71% and 4.44% of the groups, respectively.
Wong et al describe the observed rate in HBeAg-negative patients as “striking” compared with previous studies (proportion of HBeAg-negative Asian participants ranging from 24 to 100%) that have reported HBsAg loss rates of 0.0–0.7% following treatment with TDF, entecavir, or TDF plus emtricitabine.
On the other hand, the rate they observed for HBeAg-positive patients falls in the middle of the 0.0–11.8% range seen with antiviral therapy.
“While it is not clear as to the exact explanation of such high rates among our Asian cohort, underlying differences in hepatitis B virus characteristics, including yet to be discovered mutations or proteins, along with their interaction with the host patients may account for some of these observed differences,” Wong and colleagues write.
“Future studies are needed to better elucidate the underlying mechanisms of these differences so that research can harness this knowledge for future therapeutics.”
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