By Ed Susman
SYDNEY, AUSTRALIA -- July 25, 2007 - Close to 90% of patients treated with either the novel integrase inhibitor raltegravir or the standard-of-care non-nucleoside reverse transcriptase efavirenz were able to suppress HIV to undetectable levels, researchers said here at the 4th International AIDS Society (IAS) Conference on HIV Pathogenesis, Treatment and Prevention.
However, Martin Markowitz, MD, Clinical Director, Aaron Diamond AIDS Research Center, New York, New York, said that treatment with raltegravir -- which is still awaiting approval by the US Food and Drug Administration -- caused fewer adverse effects in the patients during the 48-week trial.
Dr. Markowitz and colleagues enrolled 198 treatment-naive patients and randomized them to one of four doses of raltegravir -- 100, 200, 400, and 600 mg twice a day -- or to 600 mg a day of efavirenz. Both treatments were administered with tenofovir and lamivudine.
Regardless of the study dose, it took about 4 weeks for about 90% of patients to reach a viral load of less than 400 copies of HIV RNA per milliliter of blood, he said. In contrast, patients on efavirenz took between 8 and 12 weeks to reach the same level.
"The FDA application for raltegravir is for its use in patients who have had previous antiretroviral treatments but have not been able to suppress viral levels to undetectable," Dr. Markowitz said. "The studies we presented here in Sydney are exploring the possibility of using the drug early in treatment."
In the study, Dr. Markowitz noted, there was no difference in the proportions of patients who reached low levels of HIV by the end of the study. Also, the proportion of patients who experienced treatment failure -- defined as nonresponse or a rebound in viral load -- was 3% for both raltegravir and efavirenz.
The major difference between the drugs, he said, was in the side effects, with raltegravir being "more benign." There were no dose-related toxicities.
The most common side effects were the known central nervous system events of efavirenz -- abnormal dreams, dizziness, and headache -- and those were higher in the efavirenz arm.
Raltegravir also appears to be neutral with respect to changes in lipids, Dr. Markowitz said.
The study was sponsored by Merck, which is developing raltegravir. Merck has filed for approval of raltegravir with the FDA. A hearing is scheduled for September 5, 2007.
[Presentation title: Rapid Onset and Durable Antiretroviral Effect of Raltegravir (MK-0518), a Novel HIV-1 Integrase Inhibitor, as Part of Combination ART in Treatment-Naive HIV-1 Infected Patients: 48-Week Data. Abstract TUAB104]
E-Mail this DGDispatch to a colleague
