New AIDS drug works faster to reduce virus


LOS ANGELES -- An experimental AIDS drug, part of a new class of medicines known as integrase inhibitors, worked faster in controlling HIV than one of the most widely used drugs on the market, according to a preliminary study released yesterday.

The integrase inhibitor, used in a drug cocktail with two others, cut the amount of HIV in 90 percent of patients to undetectable levels in 24 weeks. Much of the reduction occurred in the first four to eight weeks, said Dr. Robin Isaacs, who led the research.

Isaacs, executive director of clinical research for the drug's maker, Merck & Co., said those results were achieved faster than with a drug cocktail that included efavirenz, commonly used as a first treatment for newly infected patients.

The study, conducted by Merck, was released yesterday to coincide with the start of the International AIDS Conference in Toronto.

The integrase inhibitors "really look fantastic, with very few side effects," said Mark Wainberg, a professor at McGill University in Montreal and co-chairman of the conference.

The results encouraged researchers, who called this new class of drugs the most promising since fusion inhibitors were approved to treat AIDS, or acquired immune deficiency syndrome, by the Food and Drug Administration three years ago.

Integrase inhibitors prevent HIV, or human immunodeficiency virus, from replicating by blocking its ability to patch its DNA onto a cell's.

The Merck drug, when combined with two others, tenofovir and lamivudine, appeared promising for new patients and patients who have been on drug therapy for a long time, Isaacs said.

In data presented this year, as many as 72 percent of patients who had developed resistance to multiple drugs saw the concentration of HIV in their blood drop to undetectable levels after 16 weeks of taking the drug, called MK-0518.

The latest study looked at patients who recently had started drug treatment. A group of 198 patients took 100 to 600 milligrams of the integrase inhibitor twice a day, along with the two other drugs.

A control group took 600 milligrams of efavirenz once a day with the same two drugs.

The integrase-inhibitor cocktail at all doses suppressed the virus faster than the efavirenz combination did, although they performed about the same at the end of 24 weeks, Isaacs said.

The drug still has several years of testing before it can be reviewed by the FDA.

Gilead Sciences Inc. also has been testing an integrase inhibitor; its development is not as far along as the Merck drug's.

In a presentation on a 40-patient trial, Gilead researchers reported that its drug showed an almost tenfold reduction in virus multiplication when taken by itself once a day. When taken once a day with another drug that helped the integrase inhibitor last longer in the bloodstream, the reduction was hundredfold.

Drugmaker GlaxoSmithKline Inc. is also working on an integrase inhibitor, although results from the first part of its clinical trial will be presented next year.

Jia-Rui Chong writes for the Los Angeles Times.

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