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Before- and After-Sex PrEP Working Despite Low Condom Use
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21st International AIDS Conference (AIDS 2016), July 18-22, 2016, Durban, South Africa
IAS/2015: Coitally-Dependent TDF/FTC in MSM Updates on PrEP Efficacy in IPERGAY
CROI/2015: As-Needed PrEP Cuts HIV Rate 86% in French-Canadian Ipergay Trial
Mark Mascolini
Before- and after-sex preexposure prophylaxis (PrEP) with tenofovir/emtricitabine (TDF/FTC) continues to protect gay men in an open-label extension of the IPERGAY trial [1]. The only man infected with HIV 18 months into the extension had not been taking his PrEP pills. Low condom use and high sexually transmitted infection (STI) rates in IPERGAY extension participants indicate that TDF/FTC protects men who continue to have risky sex.
The IPERGAY protocol calls for men who have sex with men (MSM) to take two TDF/FTC tablets 2 to 24 hours before sex, one tablet 24 hours later, and one tablet 48 hours after the first two tablets. The randomized phase of the 400-man trial in France and Canada ended early because as-needed PrEP proved so effective [2]. After a median 9.3 months of randomized follow-up, 2 men taking TDF/FTC and 14 taking placebo became infected to yield an 86% lower HIV rate in the PrEP group (P = 0.002).
In the open-label extension phase, 362 men continued or started TDF/FTC PrEP, of whom 299 completed follow-up through July 15, 2016. The 362 men had a median age of 35 years, 93% were white, 91% completed secondary education, and 78% were single. One third had an STI in the past 6 months. These men had a median of 9.5 sex acts in the past 4 weeks and a median of 7 sex partners in the past 2 months.
At the end of follow-up, HIV incidence measured 6.60 new infections per 100 person-years in the placebo group, 0.91 per 100 with TDF/FTC in the randomized phase of the trial, and 0.19 per 100 in the open-label phase. After a median 18.4 months of follow-up, men taking TDF/FTC had a 97% relative reduction in new HIV infection compared with the placebo group. A single man became infected with HIV during the open-label extension. He had been randomized to TDF/FTC in the double-blind phase of the trial and switched to the open-label phase after 8 months. He got diagnosed with HIV 40 days later but reported not using PrEP in months. Tenofovir and FTC could not be detected in his blood at HIV diagnosis. The man was in a stable relationship with a single partner who had HIV infection.
Defining correct dosing as at least one pill before and one after sex, the IPERGAY investigators charted correct rates of 42% during the double-blind phase and 50% during the open-label phase (P = 0.007). Suboptimal dosing rates in the double-blind and open-label phases were 29% and 24% and no-PrEP rates 29% and 26%.
About 70% of men reported not using a condom during their last receptive anal sex through the double-blind part of the study. The rate of condom-free receptive anal sex rose from 77% at the start of the open-label phase to 88% at the end of follow-up, a significant jump (P = 0.0003). Rates of all STIs climbed from 37% of men in the double-blind phase of IPERGAY to 58% in the open-label phase, as first STI incidence rose from 35.2 to 40.6 cases per 100 person-years. Syphilis incidence nearly doubled from 10% to 19%.
The IPERGAY researchers concluded that "low condom use in the open-label phase did not undermine efficacy" of as-needed PrEP with TDF/FTC. They stressed that the high STI rate with as-needed PrEP needs to be addressed. Although the CDC has yet to sanction before- and after-sex PrEP in the United States, the strategy is now recommended in France, Britain, the European Union, and Canada.
References
1. Molina JM, Charreau I, Spire B, et al. Efficacy of on demand PrEP with TDF-FTC in the ANRS IPERGAY open-label extension study. 21st International AIDS Conference (AIDS 2016). July 18-22, 2016. Durban, South Africa. Abstract WEAC0102.
2. Molina JM, Capitant C, Spire B, et al. On-demand preexposure prophylaxis in men at high risk for HIV-1 infection. N Engl J Med. 2015;373:2237-2246. http://www.nejm.org/doi/full/10.1056/NEJMoa1506273
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