Tenofovir Alafenamide May Offer Safety Benefit over Tenofovir Disoproxil Fumarate

Keith Henry, MD

Results from a phase II study suggest that TAF may have less renal and bone toxicity than TDF when combined with elvitegravir/cobicistat/FTC.

Because of its safety and efficacy, tenofovir disoproxil fumarate (TDF) is an important component of many key antiretroviral therapy regimens, despite concerns about renal and bone toxicity with long-term use. Tenofovir alafenamide (TAF) addresses some of those concerns, in part because the plasma levels needed to maintain antiviral efficacy are lower.

In a recent manufacturer-funded, phase II, double-blind study, researchers compared the safety and efficacy of single-tablet regimens containing elvitegravir/cobicistat/FTC plus either TAF (25 mg) or TDF (300 mg). Study participants — 170 HIV-infected, treatment-naive adults — were randomized 2:1 to the TAF or TDF formulation.

At 48 weeks, 88% of each study arm had viral loads <50 copies/mL. TAF-arm patients had a smaller median reduction in estimated creatinine clearance than TDF-arm patients (–5.5 vs. –1 mL/min) and a lower median decrease in bone-mineral density both in the hip (–0.6% vs. –2.4%) and in the lumbar spine (–1.0 vs. –3.4%). They also had greater increases in total, LDL, and HDL cholesterol levels, but the total/HDL cholesterol ratio remained unchanged in both arms. Both regimens were well tolerated.

Citation(s):

Sax PE et al. Tenofovir alafenamide vs. tenofovir disoproxil fumarate in single tablet regimens for initial HIV-1 therapy: A randomized phase 2 study. J Acquir Immune Defic Syndr 2014 Sep 1; 67:52.