Introduction: Elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate(E/C/F/TDF) demonstrated superior efficacy when compared to atazanavir boosted by ritonavir(ATV/r+F/TDF) in 575 treatment naïve women at Week(W) 48. We now report the safety and efficacy of subsequent switching to E/C/F/tenofovir alafenamide(TAF) versus remaining on ATV/r+F/TDF.

Methods: After completing the initial randomised, blinded 48-week trial,women on ATV/r+F/TDF were randomised 3:1 to receive open label E/C/F/TAF versus remaining on their current regimen. Viral suppression by FDA snapshot analysis,pre-defined bone and renal safetyand tolerability endpoints 48 weeks after switch are reported. Women who become pregnant while on study are given the option to continue study drug.

Results: 212 HIV-infected, virologically suppressed women were randomized(E/C/F/TAF n=159, ATV/r+F/TDF n=53). Virologic suppression(<50c/mL) was maintained in 94.3% on E/C/F/TAF vs 86.8% on ATV/r+F/TDF with virologic failure in 1.9%, 3.8%, respectively. More women on E/C/F/TAF achieved <20c/mL at W48 compared to ATV/r+F/TDF (84.9% versus 71.7%p=0.041). No treatment emergent resistance was detected in either group. Mean % increase in BMD was higher in the TAF group for both lumbar spine and total hip. Multiple markers of renal safety were improved for participants randomized to TAF. No cases of proximal renal tubulopathy were reported. Nineteen women became pregnant during the switch study 13 E/C/F/TAF, 6 ATV/r+F/TDF,3 normal infants have been delivered in each group to date.

Conclusion: These data demonstrate that women who switch to an integrase inhibitor+TAF-based regimen maintain high levels of virologic suppression with improvement in BMD and renal function biomarkers compared with those remaining on their  ATV/r+TDF-based regimen.

Efficacy and Safety of Switching to EVG/COBI/FTC/TAF in Virologically Suppressed Women

The Joint Annual Conference of the British Association for Sexual Health and HIV & the Society for the Study of Sexually Transmitted Diseases in Ireland