WASHINGTON (AP) -- A failed HIV therapy should be sold instead to treat the liver-destroying hepatitis B virus, advisers to the Food and Drug Administration ruled Tuesday.
If the FDA agrees, Gilead Sciences' adefovir would become the first new treatment in years for the estimated 1.2 million Americans struggling with the potentially deadly infection.
The FDA isn't bound by its advisers' recommendations but typically follows them.
Hepatitis B, which can lead to cirrhosis and liver cancer, is transmitted through blood, bodily fluids, shared needles, and from mother to child. Children are routinely vaccinated against hepatitis B, and it's recommended that adults at risk for hepatitis B get the inoculation, too. Despite all the work at preventing hepatitis infection, the government estimates about 4,000 people a year die of the virus.
There are two other treatments, but patients can become resistant to one of the drugs and many can't tolerate the side effects of the other medicine. So doctors have longed for another option.
Adefovir originally was tested as a potential treatment for the AIDS virus, but the FDA rejected that use because the high doses required proved toxic to patients' kidneys.
So Gilead tested far lower doses as a hepatitis B treatment. It didn't cure the chronic infection -- but studies concluded that liver cirrhosis, as measured by biopsies, improved in between 56 percent and 66 percent of patients testing the drug, said company vice president John Milligan.
Taking 10 milligrams once a day didn't appear to cause outright kidney damage, Milligan said.
But it is still a potential side effect: By a more conservative measurement, up to 5 percent of patients who used adefovir for a year showed early signs of some toxicity, he said.
And the risk appears to increase as patients take the drug for longer than a year, said FDA antiviral drugs chief Dr. Debra Birnkrant.
So while the FDA panel said adefovir's benefit means it should be sold, the advisers recommended that all patients get a blood test to check for kidney damage every month or two for as long as they take the drug, she said.
Stopping adefovir at the first sign of kidney damage allows most people to recover, she said, but the risk proved greater for more advanced hepatitis patients.
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