Background/introduction Tenofovir alafenamide (TAF) is a tenofovir prodrug that contains elvitegravir 150mg/cobicistat 150mg/FTC 200mg/TAF 10mg (E/C/F/TAF).

Aim(s)/objectives This study assessed efficacy and possible bone and renal safety advantages in patients who switched from a TDF-based regimen to E/C/F/TAF.

Methods Virologically suppressed (HIV-1 RNA < 50 copies/ml) adults on a TDF-based regimen for at least 96 weeks were randomised 2:1 to switch to open label E/C/F/TAF or to continue their prior regimen. At baseline, the median CD4 count was 658 cells/uL, the median eGFR(Cockcroft-Gault) was 103.8 mL/min and 10.6% of patients had baseline proteinuria of at least 1+ on dipstick analysis.

Results At Week 48, 390/402 (97.0%) of those who switched to E/C/F/TAF and 183/199 (92.0%) of those continuing boosted ATV plus FTC/TDF had HIV-1 RNA < 50 c/mL (difference, 5.1%; 95% CI: 0.9% to 9.2%). No patients had virologic failure with resistance. In patients who switched, hip and spine bone mineral density (BMD) improved significantly, and proteinuria and specific tubular proteinuria also improved significantly Serum creatinine mean change (µmol/L) from baseline: E/C/F/TAF, +0.88; ATV+ FTC/TDF, +3.54 (p = 0.003). E/C/F/TAF patients had statistically higher changes from baseline in fasted lipid tests; the median change in total cholesterol: HDL ratio was: E/C/F/TAF, +0.2; boosted ATV+FTC/TDF, +0.0 (p = 0.001).

Discussion/conclusion At Week 48, patients who switched from a boosted ATV+FTC/TDF regimen to E/C/F/TAF had a significantly higher rate of virologic control, had significant improvements in hip BMD, spine BMD and in serum creatinine, and also had significantly less proteinuria than those continuing on their TDF-based regimen.