STRATEGY-PI is a 96 week , international , multicentre , randomised , open-label , phase 3b trial in which HIV-infected adults with a plasma HIV-1 RNA viral load of less than 50 copies per mL for at least 6 months who were taking a ritonavir-boosted protease inhibitor with emtricitabine plus tenofovir were randomly assigned ( 2:1 ) either to switch to coformulated elvitegravir , cobicistat , emtricitabine , and tenofovir or to continue on their existing regimen .