Elvitegravir is a once-daily integrase inhibitor that requires PK boosting with either ritonavir or cobicistat. It recently received FDA approval for initial therapy as part of a fixed-dose combination that includes cobicistat, tenofovir, and emtricitabine (Stribild).
Results from a study of elvitegravir in treatment-experienced patients were presented recently at the IAS conference. Study subjects with resistance to at least two ARV classes were randomized to receive either elvitegravir or raltegravir, in combination with a ritonavir-boosted PI and at least one other active ARV. After 96 weeks of treatment, rates of HIV control in the two groups were comparable (<50 copies/mL in 48% and 45% of subjects, respectively), as were CD4 increases. Adverse effects were quite similar in elvitegravir and raltegravir recipients.
In subjects who experienced virologic failure, the overall numbers of those who developed integrase resistance were comparable, but the two integrase inhibitors differed in the specific mutations they most commonly selected.
Clinical Bottom Line
Elvitegravir may be effective when used in combination with a ritonavir-boosted PI and other active agents in treatment-experienced patients. More data on elvitegravir resistance are needed to clarify whether subsequent integrase inhibitor therapy (eg, with dolutegravir) would be effective. The FDA is considering approval of elvitegravir as a stand-alone agent.