On Thursday, Myriad Pharmaceuticals Inc. announced the results of two clinical studies, which revealed findings about a new HIV drug called MPC-4326 (bevirimat dimeglumine).

MPC-4326 is a candidate antiretroviral drug with a unique mechanism of action. It completed a phase 2a clinical trial in 2008, and will undergo phase 2b in 2009. The studies’ abstracts will be presented at the Interscience Conference on Antimicrobial Agents and Chemotherapy Annual Meeting, held September 12-15 in San Francisco.

MPC-4326 fights HIV in a new way and is therefore first in a novel class of HIV drugs called maturation inhibitors. It blocks the HIV protein Gag from developing normally, which in turn prevents the formation of structurally intact HIV viruses. These viruses are “immature” and noninfectious. Drugs that combat HIV in new ways, like MPC-4326, are needed to overcome the evolution of HIV drug resistance to currently available therapies.

The first clinical study examined the efficacy and safety of singly administering 200- and 300- milligrams (mg) of MPC-4326 to HIV-infected individuals. The second clinical study (part a) looked at the pharmacokinetics, or the fate of drug substances administered externally, of a novel 100-mg MPC-4326 tablet.

The results of these studies are promising and have earned Fast Track designation by the U.S. Food and Drug Administration to speed up the clinical trial period and market release date. These preliminary studies show that MPC-4326 significantly lowers viral load, or the amount of virus in the blood, in both treatment- naïve and treatment-experienced patients.

These studies also show that some HIV strains are more sensitive to MPC-4326, which can be determined by a simple genetic test. Approximately 60 percent of all HIV-infected individuals have these sensitive HIV strains. These include strains that are resistant to currently approved HIV therapies.

MPC-4326 has not been shown to interact with other HIV drugs. Side effects are mild and include headache, nausea, diarrhea, and abdominal cramps. MPC-4326 strengthens combination therapy regimens containing protease inhibitors.

For more information, please visit the Myriad Pharmaceuticals Web site.