Antiretroviral use before sex among men who have sex with men has shown early success

But “pre-exposure prophylaxis” raises ethical issues for current, future HIV prevention trials

 
Researchers in the fight against AIDS applauded the findings of a new study on the daily use of an antiretroviral pill to protect men who have sex with men from acquiring HIV. According to a study reported in the New England Journal of Medicine on Dec. 30, 2010, the so-named preventive strategy pre-exposure prophylaxis , or PrEP, resulted in a 43.8 percent lower infection rate in a group of 1,251 men and transgendered participants who were assigned to take the pill, compared to a similar control group of 1,248 who were assigned to receive a placebo.

 

In addition, the infection rate among participants who took the pill at least 90 percent of the days, over the 2.5-year-long study, was 72.8 percent lower than it was for the control group. The findings were reported by the international iPrEX (Pre-exposure Prophylaxis Initiative) team.

 

HIV prevention researchers say they have seen few other successes of this kind, or of this magnitude. The first major success in HIV prevention was the use of antiretrovirals in women at the time of labor and delivery to prevent mother-to-newborn transmission of HIV. The second major success was male circumcision, which was found to decrease the risk of HIV infection for men during intercourse with women.

 

Jeremy Sugarman“The iPrEX findings are phenomenally important in HIV prevention research,” said Jeremy Sugarman, M.D., M.P.H., M.A., deputy director for medicine at the Johns Hopkins Berman Institute of Bioethics. “Prevention is the key to fighting this epidemic.”

 

AIDS has killed more than 25 million people since the epidemic began in the early 1980s. A total of 2.6 million people were newly infected with HIV in 2009, according to the World Health Organization. The iPrEX team was led by Robert Grant, a virologist with the J. David Gladstone Institutes at the University of California, San Francisco. The 11-site, six-country study was supported in part by the Bill and Melinda Gates Foundation.

 
An article in Science on Dec. 3, 2010, reported that some HIV prevention researchers were so overwhelmed by the iPrEX findings when the team previewed them in October that a few “even cried.”

 

However, Sugarman also cautioned that elation over the success of the iPrEX study must not blind researchers or the public to its limitations. He noted that the study showed that pre-exposure prophylaxis with the antiretroviral pill—sold under the name Truvada—lowered the risk of HIV infection only among men who  frequently had sex with other men.  Further, the participants in the trial had many partners—on average, 18 in the 12 weeks leading up to enrollment.

 

But now that researchers have data about PrEP’s effectiveness, those who plan to conduct follow-up studies on similar population groups may be confronted with new ethical questions about how best to protect participants in light of the iPrEX results. Currently, four other trials testing the efficacy of PrEP on different population groups—involving a total of 16,000 heterosexuals and injecting drug users around the world—are underway.

 

Sugarman, who chairs the Ethics Working Group for the HIV Prevention Trials Network (HPTN), said the key for researchers conducting those studies in the wake of the good news is to first determine whether the iPrEX results are relevant or applicable to their respective study populations.

 

If so, then there is probably—at minimum—an obligation to inform participants about the iPrEX results, Sugarman said. Depending on the similarities in the populations, researchers may need to have participants re-consent to be in a trial, given the new information about PrEP.

 

Sugarman said that questions about researchers’ obligations in the wake of the iPrEX trial are best answered by the data safety monitoring boards and institutional review boards for the respective trials.

 

HPTN brings together experts from around the world who are interested in developing and testing the safety and efficacy of primarily non-vaccine interventions to prevent HIV infection. The network has published guidelines for the ethical conduct of HIV prevention trials, and one section in particular speaks to a critical issue that PrEP raises: “standard of prevention” in HIV prevention research.

 

In this setting, “standard of prevention” refers to an acceptable level of protection that has been generally agreed upon by experts. The medical procedures and treatments that provide protection are included in what is commonly referred to as the “prevention package,” which is offered to all participants in HIV prevention trials in order to minimize the risk of infection during the course of research.

 

HPTN’s Ethics Guidance Document states that all who sponsor or conduct clinical trials must offer participants a prevention package, and that an appropriate package should include methods of preventing HIV infection that are a) proven to be effective, b) reasonably accessible to the participants, and c) practically achievable in the local setting.

 

When research confirmed that male circumcision was an effective means of reducing men’s risk of acquiring HIV during heterosexual intercourse, the finding raised several questions about possible obligations to current and future trial participants: Should they be informed of the finding? Should male circumcision be promoted as part of the counseling process for participants? Should they be circumcised as part of the research protocol?

 

If ongoing and future studies confirm the effectiveness of pre-exposure prophylaxis in various population groups, PrEP would likely be accepted as a “standard of prevention” and then need to be included in at least some prevention packages—depending on the type of trial and population group under study.

 

“We’re looking at our portfolio to see whether there are studies that need to be adjusted in some way based on the results of the new study,” Sugarman says, “and we’re designing future trials in line with this very promising result, so we can try to answer the next set of questions related to PrEP.”

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