Study confirms efficacy of PrEP in reducing risk of HIV infection in men who have sex with men

Jul 20 2016

The last phase of ANRS IPERGAY has confirmed that "on-demand" pre-exposure prophylaxis (PrEP) is a highly effective method of reducing the risk of HIV infection in men who have sex with men and who report high-risk behavior. These results will be presented at AIDS 2016 in Durban, South Africa (18 to 22 July). From late 2016, a vast research program, ANRS PREVENIR, will assess PrEP on a large scale in Paris and its suburbs (France).

Reducing the number of new infections in populations particularly affected by HIV is more than ever a public health priority recognized by international institutions and by most developed and resource-limited countries. Pre-exposure prophylaxis, or PrEP, in which preventive antiretroviral therapy is offered to people not infected by HIV, is a new approach that is being implemented in several towns mainly in the United States, and will soon be in Europe. Paris will be the first European capital to launch an ambitious program of PrEP designed to reduce new infections in the groups most at risk.

These advances in prevention are based on clinical trials, in particular on the findings of two studies: PROUD, in England, and ANRS IPERGAY , a French-Canadian study conducted with HIV-AIDS community organization AIDES. ANRS IPERGAY is a study of "on-demand" PrEP at the time of exposure to the risk of HIV infection among seronegative men who have sex with men (MSM) and who reported at-risk behavior in the six months prior to inclusion. Started in 2012, the first phase of ANRS IPERGAY was conducted double-blind (half the group took an oral antiretroviral combining TDF and FTC [Truvada®] at the time of sexual relations, the other half took a placebo). It showed that Truvada® reduced the risk of HIV infection by 86% (Molina et al. New England Journal of Medicine Dec 3, 2015).

Final results

Once these findings became available in November 2014, ANRS IPERGAY entered its second and last phase: all participants were given Truvada®. The aim was to ensure the benefits of "on-demand" PrEP and its long-term safety and to assess its impact on sexual behavior. Professor Jean-Michel Molina (Hôpital Saint-Louis, AP-HP, Université Paris Diderot, Paris, France) presents in an oral communication the final results of this last, "open-label" phase at AIDS 2016 in Durban, South Africa (18-22 July). Dr Bruno Spire (lnserm U912-Sesstim, Marseille, France) will complete the picture by reporting an analysis of sexual behavior.

The results of the follow-up between November 2014 and June 2016 in 362 volunteers (333 who participated in the randomized phase + 29 new recruits) presented today are even more remarkable than those of the first phase: a single person, who in fact interrupted PrEP, was infected by HIV in the "open-label" phase. The incidence (the number of new cases) was therefore only 0.19 infections per 100 person-years of follow-up. The incidence in the Truvada® arm during the double-blind phase was 0.91%.

Professor Molina said "The results of the "open-label" phase of the trial confirm the very good efficacy and safety of on-demand PrEP in reducing the risk of HIV infection in high-risk MSM. These results should promote broader use of PrEP in at-risk populations in countries where justified by the epidemic situation."

Professor Jean-François Delfraissy, Director of ANRS, applauds the French decision taken in late 2015 to authorize PrEP and its reimbursement, by means of a temporary recommendation for use. "The question today is no longer to know whether PrEP is effective and should be used, but rather how to make it available rapidly to the people most at risk."

Diversified prevention

What about condom use, which remains the cornerstone of prevention of infection by HIV and other sexually transmitted diseases? A study of sexual behavior during the open-label phase of the trial revealed a slight drop in condom use, particularly among those identified as being keen users of condoms in the double-blind phase. In the vast majority of cases use of PrEP compensated for this decrease.

"The decrease in condom use in the "open-label" trial is not worrying at present," said Dr Bruno Spire. "The trial participants were sure of being protected by PrEP, which they knew is effective. A small minority of participants, however, use neither PrEP nor condoms. We must try to understand what is holding them back." Dr Spire added that "Henceforth it seems important to speak of diversified prevention, which includes freedom of choice, rather than combined prevention, because it is somewhat illusory to imagine that most people will be able to use several methods of prevention at the same time."

ANRS will soon roll out an ambitious operational research program in Paris and its suburbs among 3000 people at high risk of HIV infection (mainly MSM, transgender people, and migrants). ANRS PREVENIR is designed to reduce the number of new HIV infections and will assess how community support improves treatment adherence and keeps participants on long-term PrEP.