127 – Final Results of the ANRS PREVENIR Study With Daily or On-Demand Oral PrEP With TDF/FTC in Paris

Background

On-demand PrEP with TDF/FTC is now recommended as an alternative to daily PrEP for MSM, but long-term experience is lacking.

Methods

The ANRS Prevenir study was a prospective cohort study enrolling individuals at high risk for HIV infection using PrEP. MSM could opt for either daily or on-demand PrEP with TDF/FTC and could switch. At baseline, month 1 and every 3 months thereafter, subjects were tested for HIV using a 4^th generation combined ELISA assay. At each visit participants provided information regarding sexual behaviour, dosing regimen and drug adherence. Our main objective was to assess the overall HIV incidence in the study and per dosing regimen, as well as incidence of viral hepatitis. Safety and study retention were also assessed. This analysis used data accumulated up to May 2^nd, 2025.

Results

From May 3^rd 2017 to May 2^nd 2024, 3229 subjects were enrolled across 22 sites in the Paris region and 3209 who used PrEP were analyzed. At enrolment, median age was 36 years (IQR: 29-43), 98.7% were MSM, 0.4% were transgender individuals, 82.7% were born in France, and 48.5% were PrEP naïve. Median follow-up lasted 45.4 months (IQR: 25.2-76.3) and accumulated 13130 person-years (PY). During follow-up, PrEP was used at least 75% of the time daily, or on demand or both by 38.4%, 38.3% and 23.3% of participants, respectively. Incidence of study discontinuation was 15.0, 17.4 and 12.8 per 100 person-years in the daily, on demand and switch groups, respectively (p<0.0001). Participants who used neither condoms nor PrEP at last sexual intercourse were 2.3, 13.4 and 7.4% in the daily, on demand and switch groups, respectively (p<0.0001). Percent change from baseline in median number of partners in last 3 months was -23%, -34% and -37% in the daily, on demand and switch groups, respectively (p=0.8) but condomless receptive anal intercourse increased by 21, 29 and 50% in the daily, on demand and switch groups, respectively (p<0.01). Overall HIV incidence in the cohort was 0.11 (95% CI: 0.06-0.18) per 100 PY with 14 HIV-infections and was not significantly different by PrEP regimens (p=0.39). HCV incidence was 0.46 per 100 PY. Thirteen subjects (0.4%) discontinued PrEP for drug-related adverse events (gastrointestinal: 6, Fanconi: 1, others:6) and 4 died, 3 of suicide.

Conclusions

In this PrEP cohort, enrolling mainly MSM in Paris, HIV incidence was low despite increasing rates of condomless sex. Rate of study discontinuation was lower in participants who switched between PrEP regimens.