New HIV Drug Shows Viral Load Reduction in Treatment-Resistant Patients

A study led by Roy T. Steigbigel, M.D., Professor of Medicine, Pathology, Microbiology and Pharmacological Sciences at Stony Brook University Medical Center, and colleagues worldwide demonstrated that raltegravir, a new medication to treat HIV infection, combined with other anti-HIV medications, provided superior suppression of HIV-1 in patients with highly resistant virus compared to placebo used with other anti-HIV medications. The results, reported in the July 24 edition of the New England Journal of Medicine, are for 48 weeks of therapy from two pivotal Phase III studies of 699 patients.

Resistance to antiretroviral therapies against HIV infection remains a problem for millions worldwide being treated for the infection. In fall 2007, the U.S. Food and Drug Administration granted approval of raltegravir for use in combination with other antiretroviral agents for the treatment of HIV-1 infection in treatment-experienced adult patients with HIV-1 strains resistant to multiple antiretrovial agents. The approval was based on analyses of viral load reductions and CD4 cell count increases from the start of treatment to 24 weeks in Phase III studies of the drug, which are ongoing. The 48-week data, reported in NEJM, adds to those studies.

“HIV disease is very complex and is especially difficult to manage in patients whose virus has become resistant to therapy,” says Dr. Steigbigel, Principal Investigator. “This new drug and approach, however, offers enormous hope for patients living with and being treated for HIV infection for many years.”

Dr. Steigbigel emphasizes that the 48-week results for raltegravir shows that when paired with other anti-HIV medicines, the drug effectively lowered the amount of virus in the blood to undetectable levels in 62 percent of the patients taking raltegravir plus other anti-HIV medicines, versus 33 percent of the patients receiving placebo plus other anti-HIV medicines. In total, 462 patients received the new drug and 237 received placebo.

Dr. Steigbigel also says the combination therapy with the drug helped the immune system to rebound in most patients, as CD4 cell counts were more than doubled in patients receiving raltegravir plus other anti-HIV medicines compared to patients receiving placebo plus other anti-HIV medicines.

The overall results stem from two major ongoing clinical trials (BENCHMRK-1 and BENCHMRK-2) that compares the drug in combination with other anti-HIV medicines to placebo plus other anti-HIV medicines. Patients in BENCHMRK-1 were enrolled in Europe, Asia, Australia, and South America. Patients in BENCHMRK-2 were enrolled in North and South America. Both of these studies are supported by Merck & Co, Inc., the manufacturer of raltegravir.

According to Co-investigator David Cooper, M.D., D.Sc., Professor of Medicine and Director of the National Centre in HIV Epidemiology and Clinical Research, University of South Wales, Sydney, Australia, results at week 48 were consistent across both BENCHMRK studies. Dr. Cooper also indicated that the efficacy shown after 48 weeks of treatment is consistent with observations at 24 weeks.