Oct. 2 -- WEDNESDAY, Oct. 1 (HealthDay News) -- New research offers more evidence that a new class of AIDS drug can provide major benefits for certain patients who have become immune to existing medications.
The U.S. Food and Drug Administration approved maraviroc, known by the brand name Selzentry, in August 2007 after a 24-week study showed it had beneficial effects. It was the first new HIV oral medication approved in more than a decade.
The new study followed the patients for another 24 weeks, and found that more than 40 percent of them had reduced levels of the AIDS-causing HIV virus in their blood.
"We're really able to do something we haven't been able to do before, essentially rescue someone with drug-resistant virus and gain control of their HIV infection," said principal investigator Dr. Roy Gulick, director of the Cornell HIV Clinical Trials Unit at Weill Cornell Medical College in New York City.
Since the 1990s, new generations of drugs have made major strides in treating the virus that causes AIDS. Patients are often able to control the levels of the virus in their bodies and live for years.
However, the virus has the ability to mutate and evolve, and it's often able to adjust to resist the killing powers of medications. Some people also become newly infected with strains of HIV that are already immune to certain drugs.
"Roughly, between a quarter and a third of patients [are resistant] to the classic classes of drugs," Gulick said. "These are patients who really need treatment options."
The new study, published in the Oct. 2 issue of the New England Journal of Medicine, followed 1,049 HIV patients who were resistant to three classes of HIV drugs. Some patients received doses of maraviroc, while others received a placebo. The study was funded by Pfizer Inc., the maker of the drug.
Between 42 percent and 47 percent of the patients taking maraviroc reached reduced levels of the AIDS virus in their bodies, compared to 17 percent of the placebo group.
"There were no apparent side effects or toxicity differences in patients that got maraviroc vs. placebo," Gulick said. "It looked safe and generally well-tolerated over 48 weeks."
The drug works by preventing the AIDS virus from binding to a receptor on immune cells known as CCR5. Some people are born without the receptor and are naturally resistant to the AIDS virus.
There are caveats with maraviroc: Doctors must give a $1,900 test to patients to make sure their strain of HIV would be susceptible to the drug, Gulick said. Also, researchers must follow patients on maraviroc to see if any unusual medical problems affect them over time, he said.
Dr. Barry S. Zingman, medical director of the AIDS Center at Montefiore Medical Center in New York City, and one of the doctors taking part in the study, said he has had good experiences prescribing maraviroc.
However, "many patients who need a new treatment option cannot use it" because they don't have the necessary strain of HIV, said Zingman, who has received research grants to study the drug.
In addition, he said, "there are significant interactions between maraviroc and other medications for HIV infection, making it a bit complicated to prescribe in the combination regimens that are standard around the world."
Visit the U.S. Food and Drug Administration for the list of the latest approved HIV drugs.
SOURCES: Roy Gulick, M.D., professor, medicine, and director, Cornell HIV Clinical Trials Unit, Weill Cornell Medical College, New York City; Barry S. Zingman, M.D., medical director, AIDS Center at Montefiore Medical Center, and associate professor, clinical medicine, Albert Einstein College of Medicine, New York City; Oct. 2, 2008, New England Journal of Medicine