Merck has studied Isentress 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-naive) HIV-1-infected patients through 96 weeks in a phase III study – STARTMRK.
Reportedly, in STARTMRK, Isentress patients received either Isentress or efavirenz in combination therapy. The data was presented at the 49th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) in San Francisco, CA.
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.
In the ongoing, multi-center, double-blind, randomized, active-controlled phase III STARTMRK trial, 563 treatment-naive adult patients received either 400mg ISENTRESS administered orally twice daily in combination with tenofovir/emtricitabine or 600mg 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 and for the efavirenz regimen was 106,215 copies/ml. Mean baseline CD4 cell counts were 218.9 cells/mm3 and 217.4 cells/mm3 for the groups receiving Isentress and efavirenz, respectively.
Edwin de Jesus, FACP, medical director of the Orlando Immunology Center in Orlando, said: “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. These results further confirm the findings from the 48 week analysis of this ongoing study.”