Results out soon for iPrEx study on PrEP effectiveness among MSM

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When will we see the efficacy results from the iPrEx study on Pre-Exposure Prophylaxis (PrEP) effectiveness among men who have sex with men (MSM)?

“Sooner than you think,” said Pedro Goicochea, an iPrEx trial investigator, during a conference call this afternoon convened by AVAC. The trail data is currently being analyzed, but there have been some reports that the results have already been submitted for publication.

iPrEx, or Pre-Exposure Prophylaxis Initiative, will be the first effectiveness study of oral antiretrovirals (ARVs) for prevention in HIV-negative people to report results. The trial examines whether two ARVs used to treat HIV/AIDS can also help prevent HIV acquisition in high-risk populations, in this case MSM at high risk in Brazil, Ecuador, Peru, South Africa, Thailand and the U.S. Study participants were given a once-daily combination of tenofovir and emtricitabine in one tablet (Truvada). Gilead is interested in providing Truvada for prevention, but it depends on efficacy and further discussions.

While unable to give too many details about the trial, Goicochea did have some interesting information about how the trial was designed and conducted. The participant retention rate was between 85 and 92 percent, and while side effects were present they were not so severe as to incite consideration of study redesign or rerouting.

There were seven Data Safety and Monitoring Board (DSMB) meetings throughout the study, with the last taking place Nov. 3, 2009. When the DSMB reviewed the data at that time they considered that the information collected up to that point was sufficient enough to answer the research questions at hand, Goicochea said. “Their recommendation was to stop enrolling… because the number of [seroconversion] events up to November 2009 was enough, and they did not want to exceed this number of events… We could analyze the data fine with this.”

In terms of next steps, if the study shows considerable efficacy there will be an extended phase when study medication will be provided to all study participants that decide to enroll in the extended phase, according to Goicochea.

“We didn’t consider how we would continue providing PrEP between trial phases,” Goicochea said. “Participants at this very moment do not receive any kind of medication if they come to the clinic. But they do receive diagnosis and treatment of sexually transmitted infections, condoms and counseling at no cost.”

“Depending on the level of efficacy that the results show, regulatory authorities might decide that alone this is enough [to get the product to market],” Goicochea said. “From my understanding of what FDA requires, there should be at least two clinical trials with the same population with 0.05 significance to consider licensing the product for the purpose of the trial.”

“We in the MSM community require new, innovative ways of preventing HIV and the community should take the lead in instigating the discussions to make [PrEP] available,” Goicochea said.

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