New AIDS Drug Helps Patients Immune to Other Medications

Nearly half of trial participants had essentially undetectable levels of virus in their blood

WEDNESDAY, April 4, 2007 (HealthDay News) -- A Spanish study reveals promising results for a new AIDS drug designed to help patients who are having the most trouble keeping the disease at bay.

The drug darunavir, when taken with an older drug, appears to be 4.5 times more effective than existing regimens at reducing the level of the AIDS virus in the blood to near zero, the study found.

Darunavir, known by the brand name Prezista, has been available in the United States since last summer. The findings in the study were previously available but are only now being published after they were reviewed by experts in the AIDS field, said Dr. Robert Shafer, an AIDS specialist who's familiar with the findings.

"It is a definite advance," said Shafer, an associate professor of medicine-infectious diseases at Stanford University's School of Medicine. "Physicians share a lot of information with each other, and we all know that it's helped a lot of patients who've failed multiple other drugs."

The findings are expected to be published online April 5 by the journal The Lancet.

Over the past decade, a new generation of AIDS drugs, called antiretrovirals, has allowed many HIV-infected people to live fairly normal lives. But the AIDS virus is a quick study when it comes to mutating itself to avoid drugs, and patients frequently become immune to the medications they take. That allows the virus to make patients sicker.

Complicating matters further, some people are infected with strains of HIV that are already resistant to certain drugs.

Enter darunavir, which is used when other drugs fail.

In the new study, Spanish researchers looked at 230 HIV-positive patients who were randomly assigned to receive a combination of darunavir and another AIDS drug known as ritonavir (at 600 and 100 milligrams twice daily, respectively) or other drug regimens that also utilize so-called protease inhibitors.

All the patients were suffering from advanced stages of HIV infection, and existing drugs weren't working well.

The researchers examined the patients after 48 weeks and found that 61 percent of those taking the darunavir regimen had a level of HIV genetic material that was at least 10-fold lower than it had been. Just 15 percent of the other patients, those taking the older regimen, reached that level.

Also, 45 percent of those taking darunavir had essentially undetectable levels of the HIV genetic material in their blood, compared to 10 percent of the other group.

Even though the patients had very low levels of HIV in their blood, they weren't cured; the infection hides in the body and can return.

The researchers also found that darunavir boosted the immune systems of the patients. Studies suggest this may significantly increase their chances of not going on to develop AIDS over the next three years.

Stanford's Shafer said darunavir works well without causing severe side effects, but it's not a silver bullet.

Doctors "really have to look at the data in the study to know what kind of response their patient will get," he said. "Not every patient will reach undetectable levels (of the virus). It will be important to use other drugs. Too much reliance on this drug can be a problem."

Still, for patients with advanced HIV infection, there's plenty of reason for hope, said Dr. Michael Horberg, director of HIV/AIDS policy, quality improvement, and research for the Kaiser Permanente Health Plan. "For a period, there seemed to be a little bit of stagnation in terms of new (drug) options. Now, if patients are failing regimens, they shouldn't necessarily continue plodding along with the old regimens, thinking there are no other options."

More research will determine if darunavir will help patients in the earlier stages of HIV infection, Shafer said. "It's really hard to know what the final place of this drug will be," he said. "Will it be used up front more often, or for those who failed multiple other drugs? We really have to wait for other studies."

More information

Learn more about AIDS drug resistance from the World Health Organization.

SOURCES: Robert Shafer, M.D., associate professor of medicine-infectious diseases, Stanford University School of Medicine, Palo Alto, Calif.; Michael Horberg, M.D., director of HIV/AIDS policy, quality improvement and research, Kaiser Permanente Health Plan, Santa Clara, Calif.; April 5, 2007, The Lancet, online
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