Durability of HBsAg clearance induced by NA therapy demonstrated
medwireNews: Clearance of hepatitis B surface antigen (HBsAg) with nucleos(t)ide analogs (NA) is as durable as spontaneous clearance in patients with chronic hepatitis B virus (HBV) infection, researchers report.
Henry Lik-Yuen Chan and co-investigators from The Chinese University of Hong Kong say that their findings “reaffirm that the quality of HBsAg seroclearance induced by NA is as good as that occurring spontaneously.”
The data also show that “the presence of anti-HBs [anti-HBsAg antibodies] may not be essential for maintaining HBsAg seroclearance after NA treatment,” they add.
The researchers analyzed data for 4080 patients with chronic HBV infection and at least one positive HBsAg test result that later became negative (seroclearance). Of these, 475 were treated with an NA.
The team found that around half (49.7%) of the 3563 untreated patients had confirmed HBsAg seroclearance, defined as at least two negative HBsAg results, while 2.1% had HBsAg seroreversion, defined as the reappearance of HBsAg after seroclearance.
In patients with NA-induced HBsAg seroclearance, 67.4% had confirmed HBsAg seroclearance and 2.9% had HBsAg seroreversion.
This “illustrates that HBsAg seroreversion does occur after both spontaneous and NA-induced HBsAg seroclearance, but the rates are very low and similar in both patient groups,” Chan et al remark in the Journal of Hepatology.
They report that the 5-year cumulative probability of confirmed HBsAg seroclearance was comparable in patients with spontaneous and NA-induced HBsAg seroclearance, at 88.1% versus 92.2% (p=0.964).
Among 2559 individuals with data on anti-HBs status, 53.1% developed HBsAg seroconversion, that is, they were positive for anti-HBs but negative for HBsAg.
Overall, patients who developed anti-HBs within a year of HBsAg seroclearance had a significantly higher 5-year cumulative probability of confirmed HBsAg seroclearance than those negative for anti-HBs, at 96.5% versus 85.4% (p=0.007).
A similar association was observed among untreated patients with spontaneous HBsAg clearance (94.9 vs 84.6%, p=0.006), but for patients with NA-induced seroclearance, the 5-year cumulative probability of confirmed HBsAg seroclearance did not differ significantly between those with and without anti-HBs (96.2 vs 95.2%, p=0.946).
The researchers conclude that their findings “provide some guidance on the definition of functional cure of [chronic HBV].”
“Although a single documentation of HBsAg seroclearance is often good enough to define functional cure, confirmed HBsAg seroclearance with a second HBsAg checked six months later is associated with a low risk of HBsAg seroreversion,” they write.
Chan et al add: “HBsAg seroclearance induced by NA is as stable as that occurring spontaneously, and the presence of anti-HBs may not be required in the definition of functional cure by NA treatment.”
By Laura Cowen
medwireNews is an independent medical news service provided by Springer Healthcare. © 2017 Springer Healthcare part of the Springer Nature group