Gene Predicts Response to Hepatitis C Drugs: Study
August 20, 2009
A slight variation in a person's genetic code could explain why some racial and ethnic groups respond differently to standard hepatitis C treatment, a new study finds.
In a clinical trial of 1,671 people with the most common form of hepatitis C who were taking either of two standard treatments -- Schering-Plough's Pegintron or Roche's Pegasys, plus the antiviral ribavirin -- genetics researcher David Goldstein of Duke University and colleagues found that a "spelling mistake," a one-letter error in the genetic code near the Interleukin-28B or IL28B gene, which helps fight off infections, makes a "huge, huge difference" in treatment response.
"If you look at individuals with the good-response genotype, about 80 percent of them will be cured. If you look at individuals with the poor-response genotype, about 30 percent of them will be cured," Goldstein said.
The significant difference attributed to the favorable genotype persisted across all study populations. Because it occurs most often in whites of European ancestry, it helps explain why blacks respond less well to standard treatment.
According to Goldstein, the discovery is specific enough that it can help guide treatment decisions. "It is very difficult for me to imagine this wouldn't be something that both the patient and the clinician would want to know about in deciding on a course of treatment," he said. "Right now, absent genetic information, if a patient comes into the clinic and they have no signs of liver damage, a decision is often reached to postpone treatment because the treatment is unpleasant and it often doesn't work."
"This discovery enables us to give patients valuable information that will help them and their doctors decide what is best for them," said Goldstein.
However, the finding does not mean that poor responders should not be offered therapy. Provided they have no liver damage, these patients might consider waiting for a new class of hepatitis C drugs -- protease inhibitors -- that are currently in mid-stage development, said Goldstein.
The study, "Genetic Variation in IL28B Predicts Hepatitis C Treatment-Induced Viral Clearance," was published online in Nature (2009;doi:10.1038/nature08309).
08.16.2009; Julie Steenhuysen