A study of intermittent use of Truvada (tenofovir/emtricitabine) as pre-exposure prophylaxis (PrEP) among men who have sex with men (MSM) has been stopped because the intervention showed high efficacy in preventing HIV, aidsmap reports. Run by French researchers, the IPERGAY study is the second European PrEP study recently to end because of high efficacy; the UK PROUD trial did so two weeks ago.

IPERGAY recruited about 400 MSM at six sites in France and one in Canada, beginning in February 2012. The participants were randomly assigned to receive either a placebo or Truvada, with the instructions to take two pills 12 hours before they anticipated having sex and then two separate single-pill doses each day after having sex.

Preliminary results from the study were announced at the 20th International AIDS Conference in Melbourne, Australia, in July.

The participants were all offered personal counseling, repeated HIV testing, hepatitis B virus (HBV) vaccination, condoms and personal lubricant as well as screening and treatment for other sexually transmitted infections.

After the PROUD study was discontinued and all its members received daily Truvada, the IPERGAY researchers had the trial’s data safety monitoring board unblind the study’s data. The board found that there was a significant difference in the rate of HIV acquisition between the Truvada arm and the placebo arm and that those taking PrEP enjoyed a reduction in risk for HIV that was “much higher” than the 44 percent found in the iPrEx trial, according to a press release. (IPrEx was published in 2010 and first proved PrEP’s efficacy among MSM.) The board recommended that the IPERGAY researchers offer Truvada to all the participants.

There are no further specifics available about PrEP’s efficacy when used according to this intermittent paradigm. Full results should be released early in 2015.

Both PROUD and IPERGAY will continue without placebos for another year in order to gather more data.

Anyone considering trying intermittent dosing on their own should consider that the efficacy of the strategy is still unknown. Also, it is vital to receive quarterly HIV tests when taking PrEP to help prevent the virus, should someone become HIV positive, from developing resistance to either of the components of Truvada.

To read the aidsmap story, click here.

To read the press release (the English translation is at the bottom of the page), click here.