Gilead Sciences (Gilead) has reported that Phase II clinical trial of its investigational integrase inhibitor-based, once-daily, fixed-dose ‘Quad’ regimen of elvitegravir, GS 9350 and Truvada (emtricitabine and tenofovir disoproxil fumarate), met its primary objective.
Reportedly, the ongoing study of 71 HIV-infected, antiretroviral treatment-naive adults compares the Quad with Atripla (efavirenz 600mg/emtricitabine 200mg/tenofovir disoproxil fumarate 300mg).
Elvitegravir is Gilead’s investigational HIV integrase inhibitor. GS 9350 is Gilead’s investigational pharmacoenhancing agent, being developed to increase blood levels of certain medicines, including elvitegravir, and allows for once-daily dosing.
The Quad Phase II study is a double-blind, multicenter, randomised, active-controlled 48-week clinical trial evaluating the safety and efficacy of a fixed-dose regimen containing elvitegravir, GS 9350 and Truvada versus Atripla, each administered in HIV-infected treatment-naive adults with HIV RNA levels (viral load) greater than or equal to 5,000 copies/ml and CD4 cell counts greater than 50 cells/mm3 (n=71).
In the study, trial participants were randomized 2:1 to receive a once-daily tablet containing elvitegravir 150mg/GS 9350 150mg/emtricitabine 200mg/tenofovir disoproxil fumarate 300mg or Atripla (efavirenz 600mg/emtricitabine 200mg/tenofovir disoproxil fumarate 300mg).
Reportedly, the study is ongoing. Secondary endpoints will include the proportion of patients with HIV RNA levels (viral load) less than 50 copies/ml at 48 weeks of treatment, and the safety and tolerability of the two treatment regimens through 48 weeks of treatment.
After week 48, subjects will continue to take blinded study drug until treatment assignments have been unblinded, at which point all subjects will be given the option to participate in an open-label rollover extension and receive the single-tablet regimen containing elvitegravir, GS 9350 and Truvada.
Based on 24-week data, efficacy of the Quad met the statistical criteria of non-inferiority as compared to Atripla based on the proportion of subjects with HIV RNA levels (viral load) of less than 50 copies/ml.
The company is also studying GS 9350 as a stand-alone boosting agent for other antiretrovirals, in particular, protease inhibitors. A Phase II clinical trial evaluating the safety and efficacy of GS 9350-boosted atazanavir compared to ritonavir-boosted atazanavir, each in combination with Truvada, is ongoing. Results from this study will also be submitted for presentation at a scientific meeting in early 2010.