On demand PrEP with oral TDF-FTC has been shown to reduce the incidence of HIV-1 infection in high risk MSM in the ANRS IPERGAY trial from 6.60 per 100 participants-years (py) in the placebo arm to 0.91 per 100 py in the TDF-FTC arm. However, because the placebo arm was discontinued early, the cumulative follow-up time with TDF/FTC was only 219 py and the long term efficacy and safety of this strategy remains to be demonstrated.
High risk adult MSM who were followed or being screened in the ANRS IPERGAY trial at the time of the discontinuation of the placebo arm (November 2014) were offered to continue follow-up every two months with open-label TDF/FTC. The primary study objectives of this open-label phase were to assess study retention, HIV incidence, safety and changes in sexual behaviour.
In November 2014, among the 400 pts initially enrolled in the study, 336 (84%) were eligible and all but 3 (99%) were enrolled in the open-label phase. Twenty-nine new pts were also enrolled in this open-label study. Overall, 362 pts were enrolled for a cumulative follow-up time of 248 py until September 14, 2015. Study retention was good with only 13 pts discontinuing follow-up (3.6%). During follow-up, only a single individual who had discontinued PrEP acquired HIV-1 infection. The incidence of HIV-1 infection in this open-label phase was 0.40 per 100 py (95%CI: 0.01-2.25). Pts used a mean of 18 pills/month (SD:8.7). Overall, 33% of pts acquired a new STI. There was no significant changes between the double-blinded phase and the open-label phase in the median number of sexual intercourses or sexual partners, but there was a significant decrease in condom use for receptive anal intercourse (p=0.01). Safety was good with a low rate of serious adverse events (4%). One pt discontinued TDF-FTC because of an increase in serum creatinine level. Drug-related gastrointestinal adverse events (nausea, diarrhea, abdominal pain) were reported in 10% of pts.
Open-label on demand PrEP with oral TDF-FTC remains highly effective to prevent HIV-infection in high risk MSM and has a good safety profile.