ISENTRESS® , an integrase inhibitor from Merck & Co., Inc., was studied in comparison to efavirenz in maintaining viral load suppression to undetectable levels (less than 50 copies/mL) and at improving CD4 cell counts in previously untreated (treatment-naïve) HIV-1-infected patients through 96 weeks in a Phase III study called STARTMRK. In STARTMRK, ISENTRESS patients received either ISENTRESS or efavirenz in combination therapy. The data was presented today at the 49th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in San Francisco, CA.
The U.S. Food and Drug Administration (FDA) recently approved an expanded indication for ISENTRESS on July 8, 2009, to include the treatment of adult patients starting HIV-1 therapy for the first time, as well as treatment-experienced adult patients, in combination with other antiretroviral (ARV) medicines. The expanded indication for ISENTRESS was based on analyses of plasma HIV-1 RNA levels through 48 weeks in three double-blind controlled studies. Two of these studies were conducted in clinically advanced, three-class antiretroviral [nonnucleoside reverse transcriptase inhibitor (NNRTI), nucleoside reverse transcriptase inhibitor (NRTI) and protease inhibitor (PI)] treatment-experienced adults. The third study was a 48-week analysis of the STARTMRK trial in treatment-naïve patients.
ISENTRESS is used in combination with other ARV medicines for the treatment of HIV-1 infection in adult patients. The safety and efficacy of ISENTRESS have not been established in pediatric patients. The use of other active agents with ISENTRESS is associated with a greater likelihood of treatment response.
“Results from the 96 week analysis of STARTMRK showed that ISENTRESS in combination therapy was as effective as efavirenz at suppressing HIV viral load and increasing immune system function,” said Edwin de Jesus, M.D., F.A.C.P., medical director of the Orlando Immunology Center in Orlando, Florida. "These results further confirm the findings from the 48 week analysis of this ongoing study.”
ISENTRESS studied through 96 weeks in 563 previously untreated adult patients
In this ongoing, multi-center, double-blind, randomized, active-controlled Phase III STARTMRK trial, 563 treatment-naïve adult patients received either 400 mg ISENTRESS administered orally twice daily in combination with tenofovir/emtricitabine or 600 mg efavirenz administered orally once daily in combination with the same agents. The primary endpoints were reductions in HIV-1 viral load to less than 50 copies/mL and an evaluation of safety and tolerability at Week 48. Secondary endpoints included ARV activity as measured by the proportion of patients achieving HIV viral load to less than 50 copies/mL, less than 400 copies/mL and change from baseline in CD4 count at Week 96, as well as tolerability and safety at Week 96.
Patients who entered the study were required to have HIV viral loads greater than 5,000 copies/mL. At baseline, geometric mean viral load levels for patients on the regimen including ISENTRESS was 103,205 copies/mL>3 and 217.4 cells/mm3 for the groups receiving ISENTRESS and efavirenz, respectively.
Viral load reductions and increase in CD4 cell counts maintained through 96 weeks