— Christine M. Kukka, Project Manager, HBV Advocate
Measuring the amount of hepatitis B surface antigen
(HBsAg) in your bloodstream or conducting quick tests for
drug-resistant hepatitis B virus (HBV) may soon be part of your office
visit in the brave new molecular world of hepatitis B treatment.
Doctors increasingly are
measuring HBsAg levels to determine if treatment is needed or if
current medications are working. HBsAg tests—along with measuring
alanine aminotransferase (ALT) for signs of liver damage and HBV DNA
for viral load—may become essential tools to assess hepatitis B
progression or remission.
HBsAg is the protein that makes
up the outer covering of HBV. When a patient has a high viral load
(and is positive for the hepatitis B "e" antigen—HBeAg), there are
often large quantities of HBsAg circulating in the blood stream. When
viral replication slows and HBeAg disappears, there can be lower
quantities of HBsAg.
But experts are learning that
high HBsAg levels can increase cancer risk, even in HBeAg-negative
patients, according to a study published in the journal Annales de Biologie Clinique. (1) As a result, there is heightened attention on HBsAg as a key indicator of a patient's health. For example:
- In HBeAg-negative patients, HBsAg levels less
than 1,000 international units per milliliter (IU/mL) along with low
viral load (HBV DNA) under 2,000 IU/mL indicate the patient is an
"inactive" patient.
- When patients are treated with pegylated
interferon, doctors can tell if the treatment is working if there is a
decline in HBsAg levels within 12 weeks. This early indicator can save
money if the drug isn't working and help to avoid uncomfortable side
effects. Doctors recommend patients with genotypes B and C should stop
interferon at week 12 if their HBsAg levels remain at 20,000 UI/mL or
higher.
Another team of French
researchers, also exploring the implications of HBsAg in an article
published in the February 2014 issue of the journal Liver International, suggest that as HBsAg levels decline, so does the risk of liver cancer.
They also suggest that during
antiviral treatment, a rapid decline in HBsAg may indicate which
patients will eventually clear HBsAg. A 100-fold decline or more of
HBsAg over six months of treatment, "... could be a marker of a
sustained response after treatment cessation," they wrote.(2)
In another diagnostic breakthrough, researchers writing in the December journal of Clinical Molecular Hepatology
promoted the value of a HepB Typer-Entecavir kit that can precisely
detect HBV that have viral mutations that can “resist” the antiviral
drug entecavir (Baraclude). This diagnostic tool allows doctors to
select the most effective antiviral for each individual patient based on
the molecular makeup of their HBV.(3)
Labels: diagnostic tools, drug resistance
