Science Making Headway Against Hepatitis B
Two studies point to best therapies for specific patients
WEDNESDAY, June 29, 2005 (HealthDay News) -- Two new studies suggest researchers are moving closer to finding the best treatments for chronic hepatitis B, a viral infection affecting some 400 million people worldwide.
Chronic hepatitis B is an enormously complicated disease, one that strikes different people differently and which requires nuanced treatment approaches.
"Hepatitis B patients are not alike," said Dr. Anna S.F. Lok, a professor of internal medicine and director of clinical hepatology at the University of Michigan. "Having more treatment options is good for the patient [but] it can be confusing for physicians who are not as familiar with the disease."
"It's just like going into a shop," continued Lok, who wrote an editorial that accompanies the studies in the June 30 issue of the New England Journal of Medicine. "If they only sell white blouses, that's very easy. But if they have many different styles and colors, you end up standing there for half an hour and not deciding."
Hepatitis B kills about one million people each year worldwide. The disease is caused by a virus that attacks the liver and can cause lifelong infection, scarring of the liver, liver cancer, liver failure and death. The virus can be spread from a mother to the fetus, as well as through sex and intravenous drug use.
Now, more treatments are more easily available in pill form (as opposed to injection) and scientists are racing to discover the best way to deliver different options.
One study in the new issue of the journal found that longer-term treatment with the drug adefovir dipivoxil benefited patients with hepatitis B e antigen (HBeAg)-negative chronic hepatitis B.
HBeAg-negative disease tends to represent a later phase in the course of infection and also tends to be more aggressive.
This study involved 185 HBeAg-negative patients assigned to receive adefovir dipivoxil daily or a placebo for 48 weeks. The international study was based in Athens and supported by Gilead Sciences, which makes the drug.
When the 48-week point had been reached, the patients taking the drug were again randomly assigned either to take adefovir dipivoxil for another 48 weeks or to switch to a placebo. After 96 weeks, patients taking adefovir dipivoxil were offered continued therapy and continued to be monitored.
When treatment was discontinued after 48 weeks, any benefits achieved were lost. Patients who received adefovir dipivoxil for the full 144 weeks, however, maintained the benefit, suggesting that long-term therapy will be needed in most patients, the authors stated.
A second international study, supported by drug maker Roche and led by researchers in Hong Kong, compared peginterferon alfa-2a given in conjunction with another drug, lamivudine, against each of the two therapies alone. These patients were HBeAg-positive, which usually represents an earlier phase of infection.
More than 800 patients, most of them Asian, were randomly chosen to receive one of the three treatment regimens.
After 24 weeks of follow-up, more patients receiving peginterferon either alone or in combination were showing a benefit on multiple end points.
This supports the use of peginterferon alfa-2a as a first-line therapy for people with this type of chronic hepatitis B, the authors stated.
Still, there are many issues to be worked out.
One issue involves side effects. "Many of these drugs were approved based on one year but then we found out that one year was not good enough, that we needed to continue the drugs," Lok said. "Then we started getting worried. Do we really know these drugs are safe?"
Another issue is that the virus can develop resistance to specific drugs. "Unfortunately, it's like taking the same antibiotics for a long, long time. After a while they no longer work," Lok pointed out.
Then there are the perennial questions of when to start treatment and when to stop it. "It becomes important for us to think very carefully -- 'Should I be starting this patient on treatment? Do the benefits really outweigh the risks? What, actually, is the best treatment for this particular patient?' " Lok said. "We need to balance all the benefits as well as the potential problems."
The U.S. Centers for Disease Control and Prevention has more on hepatitis B.