Dr. Robert Grant (Credit: Liz Highleyman)
Much-anticipated efficacy results from a French study of intermittent PrEP were announced at the 2015 Conference on Retroviruses and Opportunistic Infections (CROI) at the end of February. Although PrEP experts do not have enough information from this relatively small study of men to advise or recommend intermittent PrEP use, IPERGAY does add to clinical knowledge about one important issue: how to stop using PrEP if it's no longer needed.
Robert Grant, M.D., of the Gladstone Institutes, the University of California at San Francisco and chief medical officer of San Francisco AIDS Foundation, is excited to discuss the implications of the IPERGAY study, which he says will be even more exciting and relevant when the discussion includes informed PrEP users who are ultimately in charge of how PrEP is used. At this point, he's focusing on one implication of IPERGAY relevant to men now taking PrEP.
"We know that people go in and out of seasons of risk -- times when they're more likely to be exposed to HIV. Seasons of risk can start with the end of a long term relationship, the beginning of a new sexual practice, immigration to a new city, or some other change in situation -- such as going on a cruise. Perhaps sex happens on the cruise -- but then the cruise ends and the party ends. And people want to know, how do you stop PrEP, if you are no longer at risk?"
Previous PrEP use does not offer ongoing protection for future risk events once it's stopped -- PrEP is not a vaccine. For people who wish to stop PrEP because they no longer anticipate being exposed to HIV -- who are currently taking daily PrEP -- PrEP should continue until after the last possible exposure to HIV. Until now, it wasn't known how much longer PrEP needed to be taken to ensure the last HIV exposure didn't result in infection.
Previous recommendations for stopping PrEP called for an additional 28 days of PrEP use after the last possible HIV exposure through sex. This is the equivalent to the length of dosing needed for effective post-exposure prophylaxis (PEP) -- when HIV medications are started to prevent infection only after an exposure event.
But, according to Grant, "That may be more than what's needed. Two doses after a potential exposure to HIV appears to provide substantial protection in the IPERGAY study if men were taking PrEP before the exposure."
This excerpt was cross-posted with the permission of BETAblog.org. Read the full article.