— Christine M. Kukka, Project Manager, HBV Advocate
Entecavir lowers viral load, but not HBsAg levels: Chinese researchers followed 222 patients who were treated with entecavir (Baraclude) for up to five years and found that while the antiviral was very effective in lowering viral load, there was a disappointingly slow decline in HBsAg over the course of treatment.
Clearing HBsAg is an important treatment goal and it greatly reduces the risk of liver damage from the infection.
The researchers, reporting in the December issue of the Journal of Gastroenterology and Hepatology, found that viral load rapidly declined in all patients with entecavir treatment, with 97.1% achieving undetectable viral load after five years. Only two patients (representing 1.2% of those studied) developed resistance to entecavir.
However, “In contrast to the profound HBV DNA suppression, long-term entecavir treatment only achieved a slow decline in serum HBsAg,” they wrote. “…Additional therapeutic agents are needed to increase the chance of HBsAg clearance in chronic hepatitis B.”
One-third of patients who respond quickly to entecavir clear HBeAg: About 31% of hepatitis B “e” antigen (HBeAg-positive) patients who achieve undetectable HBV DNA after six months of entecavir treatment will lose HBeAg after two years of treatment, according to a Taiwanese study published in the December 2013 issue of the Journal of the Formosan Medical Association.
Researchers followed 68 HBeAg-positive patients (75% male, average age 46) and found that 30.9% of them lost HBeAg after two years of treatment. Patients who responded well to the antiviral after just six months of treatment and achieved undetectable HBV DNA usually went on to clear HBeAg within two years.
Study finds genetics—not drug resistance—is why some patients don’t respond to entecavir: While entecavir is recommended as one of the top, first-line treatments for hepatitis B, a small percentage of patients respond slowly to the antiviral.
Researchers have suspected that some people may harbor virus with mutations that are able to “resist” entecavir’s ability to halt viral replication. However, a study published in the November 2013 journal Antiviral Therapy, finds that a weak immune system may be the culprit.
Italian researchers analyzed HBV from five people who responded quickly to entecavir and five who responded slowly. They found no entecavir-resistant virus in patients who failed to respond, instead they found a weak immune response that… “might be at odds in rapidly clearing infected cells from the liver.”