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'On-demand' PrEP regimen successful among MSM
SEATTLE — An “on-demand” pre-exposure prophylaxis regimen was highly successful at preventing HIV among men who have sex with men, according to results of the ANRS Ipergay trial.
The regimen involves taking Truvada (tenofovir/emtricitabine, Gilead Sciences) before and after each sexual encounter: two pills taken 2 to 24 hours before sex, one pill taken 24 hours later and one pill taken 48 hours after the first drug intake.
“Adherence is the ‘Achilles’ heel’ of PrEP,” Jean-Michel Molina, MD, PhD, of Paris Diderot University, said during his presentation. “This more convenient dosing regimen could improve adherence, safety and cost-effectiveness, making PrEP more attractive.”
Molina and colleagues evaluated the on-demand regimen in a randomized trial that included 414 HIV-negative, high-risk MSM who were randomly assigned to the on-demand regimen or placebo. Both patient groups also received full prevention services, including counseling, condoms and gels, testing and treatment for STDs, vaccination for hepatitis B and hepatitis A viruses and post-exposure prophylaxis (PEP). The primary efficacy endpoint was HIV seroconversion, and secondary endpoints included safety and tolerability, adherence, sexual behavior and STDs.
The modified intention-to-treat analysis included 176 participants who were assigned to PrEP and 177 who were assigned to placebo. The baseline characteristics were similar between the two groups. After a mean follow-up of 13 months, there were 16 infections — 14 in the placebo arm and two in the PrEP arm. This translated to an 86% relative reduction in the incidence of HIV associated with the PrEP regimen. Molina said the incidence of HIV infection in the placebo arm was higher than expected.
Adherence was similar between the two arms as was the number of participants who received PEP. There was no difference in serious adverse events between the two groups, but participants who received PrEP experienced more drug-related gastrointestinal toxicities (P = .02).
“Adherence to PrEP was good, supporting the acceptability of on-demand PrEP, and there was no evidence of risk compensation,” Molina said. “On demand PrEP is an attractive alternative to daily PrEP in high-risk MSM who do not use condoms consistently.” – by Emily Shafer
Reference:
Molina JM, et al. Abstract #LB23. On Demand PrEP With Oral TDF-FTC in MSM: Results of the ANRS Ipergay Trial. Presented at: Conference on Retroviruses and Opportunistic Infections; Feb. 23-26, 2015; Seattle.
Disclosure: Molina is a board member of Bristol-Myers Squibb, Gilead Sciences, Janssen, Merck and ViiV Healthcare.
Perspective
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One of the most significant developments in preventing HIV transmission is PrEP. Already at this year’s CROI, we have seen very interesting new data suggesting an evolution in PrEP strategies. We are seeing even more evidence that PrEP success is closely linked to levels of adherence. And in one of the more novel approaches, a French trial has shown that intermittent PrEP was highly effective.
In this trial, MSM took the combination pill of tenofovir and emtricitabine shortly before and for two days after possible sexual exposure to HIV. A placebo controlled trial was halted early because of clear PrEP benefit. This approach might decrease the cost of PrEP programs and possible toxicity. We will eagerly wait for the details of this trial but it offers substantial excitement for the use of PrEP to slow the epidemic of HIV in MSM populations.