this is the only phase-3 study GILD needs to obtain approval for Elvitegravir—provided, of course, that there are no safety problems.
In the PR you've posted, GILD indicated that
The nature and frequency of Grade 3/4 adverse events and laboratory abnormalities were similar between the two arms...Discontinuation rates due to adverse events were comparable in both arms of the study.
The study is ongoing in a blinded fashion, but I expect Elvitegravir to be as safe as Isentress.