Merck announces results from ISENTRESS Phase III combination study on HIV-1

Merck (NYSE: MRK), known as MSD outside the United States and Canada, today announced results of new exploratory pre-specified analyses from the ongoing STARTMRK Phase III study of its integrase inhibitor ISENTRESS^® (raltegravir) Tablets in combination therapy compared to efavirenz in combination therapy in previously untreated (treatment-naïve) adult HIV-1-infected patients. The analyses showed that the regimen containing ISENTRESS demonstrated better efficacy compared to the regimen containing efavirenz at 192 weeks of treatment, as measured by the percentage of patients maintaining undetectable virus levels (less than 50 copies/mL) [76.2 percent>3; CI 24.1, 95.4) versus the efavirenz regimen.

"These results offer further insight into the virologic and immunologic response seen with ISENTRESS in combination therapy when compared to efavirenz at 192 weeks in treatment-naïve adult patients with HIV-1," said Dr. Jürgen Rockstroh, University of Bonn, Bonn-Venusberg, Germany, who presented the data.

ISENTRESS is indicated in combination with other antiretroviral (ARV) agents for the treatment of HIV-1 infection in adult patients. The label for ISENTRESS is based on analyses of plasma HIV-1 RNA levels through 96 weeks in three double-blind controlled Phase III clinical studies of ISENTRESS. Two of these studies were conducted in clinically advanced, three-class ARV [non-nucleoside reverse transcriptase inhibitor (NNRTI), nucleoside reverse transcriptase inhibitor (NRTI), protease inhibitor (PI)] treatment-experienced adults and one was conducted in treatment-naïve adults. The use of other active agents with ISENTRESS is associated with a greater likelihood of treatment response. The safety and efficacy of ISENTRESS have not been established in pediatric patients.

Additionally, based on analyses of pre-specified demographics (age, gender, region, race and hepatitis co-infection) and baseline prognostic factors (viral load, CD4-cell count and HIV-1 subtypes), ISENTRESS in combination therapy demonstrated consistent virologic and immunologic efficacy relative to efavirenz in combination therapy at week 192. Data also showed that ISENTRESS in combination therapy resulted in fewer reported drug-related clinical adverse events (AEs) than combination therapy with efavirenz. These findings were presented for the first time today at the 13^th European AIDS Conference (EACS 2011) in Belgrade, Serbia.