WASHINGTON A new class of HIV drugs can help control the virus in untreated patients, researchers reported on Sunday.
Merck and Co. hopes the findings will open a new market for its drug Isentress, the first drug on the market in a new class called integrase inhibitors.
Isentress worked slightly better than an older HIV drug called efavirenz in suppressing levels of the AIDS virus, the researchers told a meeting of the American Society of Microbiology and the Infectious Diseases Society of America.
Last October, the U.S. Food and Drug Administration cleared Isentress for use in HIV patients whose infection has begun to resist the effects of other drugs.
This problem, called resistance, is common in AIDS virus infections and is one reason why companies continue to develop new drugs to fight HIV.
Companies want their drugs to be approved for first-line treatment against HIV, as well. The human immunodeficiency virus that causes AIDS has no cure, but a cocktail of various drugs can control the infection and keep patients healthy.
Isentress, known generically as raltegravir, is sold as a twice-daily pill.
Cowen & Co analysts have forecast that the drug could reap up to a $1 billion in sales by 2012. The drug could compete with another integrase inhibitor called elvitegravir being tested by Gilead Sciences.
Merck estimates about 500,000 patients in the United States are getting these drug cocktails and that between 30 and 40 percent of them have developed resistance.
The U.S. Centers for Disease Control and Prevention estimates that about a million people in the United States are infected with HIV. Globally, 33 million are infected with the fatal and incurable virus.
Merck's phase III study -- the last stage of testing before seeking FDA approval -- found that Isentress reduced HIV viral load to undetectable levels in 86 percent of patients compared to 82 percent of patients treated with efavirenz.
The 500 patients were also taking the HIV drugs tenofovir and emtricitabine.
(Reporting by Maggie Fox, editing by Will Dunham)