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The first treatment studied combines a drug currently called ABT-450/r and one called ABT-333. Together, these drugs achieved up to a 95 percent sustained response, meaning the drugs suppressed levels of hepatitis C in the blood over time.
Both drugs require just 12 weeks of treatment compared to today's standard of 48 weeks, according to the authors.
"Over the next few years, we're going to have several new options to eradicate the hepatitis C virus," said the lead author of the ABT-450/r study, Dr. Fred Poordad, a professor of medicine at the University of Texas Health Science Center in San Antonio.
"We're hopeful that in the next 10 years, we should be able to eradicate hepatitis C in most Americans," said Poordad.
Both studies appear in the Jan. 3 issue of the New England Journal of Medicine. The ABT-450/r study was funded by the drug maker, Abbott Pharmaceuticals, and the sofosbuvir study was funded by drug makers Pharmasset and Gilead Sciences.
More than 3 million Americans have hepatitis C, a contagious liver disease usually spread through contact with the blood of someone already infected, according to the U.S. Centers for Disease Control and Prevention. The infection can be either acute or chronic. Chronic hepatitis C can scar the liver and eventually lead to liver failure. Poordad said it's one of the most common reasons for a liver transplant.
The current treatment combines two medications: interferon and ribavirin. Interferon is only available by injection, and must be administered three times a week for 48 weeks. Ribavirin is a pill. Side effects of interferon, which can last the duration of treatment, include flu-like symptoms, such as fever, chills, muscle aches and headache.
Poordad explained that this is because interferon dampens the whole immune system to keep the virus at bay. The new medications are what's called targeted therapies, which specifically go after the hepatitis C virus instead of attacking the whole immune system, he said.
"We're giving a drug that's killing the virus without bothering the host (the person with hepatitis C)," said Poordad.
His study had 50 people with genotype 1 hepatitis C, the most common and hardest-to-treat form of hepatitis C, according to Poordad. None had developed liver scarring (cirrhosis) yet.
Study volunteers were split into three groups. One group had never been treated for hepatitis C and received ABT-333, ribavirin and 250 milligrams (mg) of ABT-450 with 100 mg of ritonavir (making the ABT-450/r combination). The second group had also never received treatment. They received the same medications, except their dose of ABT-450 was 150 mg. The third group had received treatment for hepatitis C but had had no response or only a partial response to treatment. They were given ABT-333, ribavirin and 150 mg of ABT-450 and 100 mg of ritonavir.
The first two groups had a 95 percent and 93 percent sustained response to the drug. In the third group, only 47 percent had a sustained virologic response, the investigators found.
The second study, conducted in New Zealand, included 95 people with hepatitis C genotypes 1, 2 or 3. They were split into eight groups and received varying treatments. All of the treatments included 400 mg of the new drug sofosbuvir.
Sustained response rates were impressive -- 100 percent -- when sofosbuvir was combined with ribavirin, or with interferon for people with genotypes 2 and 3. When sofosbuvir was given alone, it achieved a sustained response rate of 60 percent for those with genotypes 2 and 3.
For those with genotype 1 who had never received treatment, sofosbuvir and ribavirin achieved an 84 percent sustained response. For those who hadn't responded to prior treatment, this combination resulted in just a 10 percent sustained viral response rate.
Like ABT-450/r, the side effects for sofosbuvir included headache, fatigue, nausea and skin rash.
Experts welcomed the findings.
"Overall, these results are encouraging, and there's definitely a need for new treatments," said liver specialist Dr. Natasha Von Roenn, from Loyola University Medical Center in Chicago.
"Headache seemed to be a significant side effect in both studies, but the good news was that none of the patients had to stop treatment because of side effects," she noted.
"We're moving closer to having an oral interferon-free regimen with good response rates," she added.
Both studies were phase 2 studies, so neither treatment is yet available.
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