Co-Author: Susa Coffey, MD; Medical Editor, AETC National Resource Center
An open-label study is evaluating the renal safety of elvitegravir/cobicistat/emtricitabine/tenofovir (Stribild, or the "quad" pill) and cobicistat. For those patients with mild-to-moderate renal impairment (estimated glomerular filtration rate [eGFR]: 50 to <90 mL/min).
The study comprises 2 treatment groups:
- Treatment-naive patients treated with elvitegravir/cobicistat/emtricitabine/tenofovir DF (n=33)
- Patients receiving atazanavir/ritonavir or darunavir/ritonavir with 2 NRTIs who were switched from ritonavir to cobicistat; these patients had HIV RNA levels of <50 copies/mL at baseline; 70% of patients were taking tenofovir DF as part of their regimen (n=73)
At the interim 24-week analysis, there were small changes in eGFR, consistent with changes reported in Phase III clinical trials. As in other studies, there were no significant changes in actual GFR in a subgroup measured by iohexol clearance. The study reported no difference in eGFR changes in subjects with baseline eGFR of ≤70 mL/min vs those with baseline eGFR of >70 mL/min, but unfortunately, less than half the patients in both arms had eGFR of ≤70 mL/min at baseline.
Clinical Bottom Line
A majority of patients in this study had eGFR of 70-89 mL/min at baseline, indicating very mild (if any) renal impairment. These patients already fall within the prescribing guidelines (elvitegravir/cobicistat/emtricitabine/tenofovir is recommended only for otherwise appropriate patients with creatinine clearance [CrCl] of >70 mL/min). Given the very small number of subjects in the 2 groups with baseline eGFR of <70 mL/min, the results of this study should not be extrapolated to determine that elvitegravir/cobicistat/emtricitabine/tenofovir (Stribild) or cobicistat are safe or appropriate in this patient population; additional data are needed.
Thus, the current recommendation is to follow the package insert instructions and the DHHS guidelines by considering use of the quad pill only for patients with CrCl >70 mL/min at baseline, and to discontinue the quad when patients' CrCl falls to <50 mL/min.
Post F, Andrade Villanueva J, Fisher M, et al. Renal safety of elvitegravir/cobicistat/emtricitabine/tenofovir DF (STB) and cobicistat-boosted protease inhibitor regimens in HIV-1- infected patients with mild to moderate renal impairment. In: Program and abstracts of the 7th International AIDS Society Conference on HIV Pathogenesis, Treatment, and Prevention; June 30-July 3, 2013; Kuala Lumpur, Malaysia. Abstract TuPE280.