September 25, 2015
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PrEP protects high-risk MSM against HIV-1 infection

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Daily oral pre-exposure prophylaxis treatment with Truvada appeared to reduce HIV-1 infection among high-risk men who have sex with men, according to recently published pilot-phase data from the PROUD study.

“The biological efficacy of daily oral tenofovir-based regimens used as PrEP to reduce HIV acquisition has been established through randomized placebo-controlled trials including [MSM], heterosexual individuals and intravenous drug users,” Sheena McCormack, MD, senior clinical scientist in the Medical Research Council Clinical Trials Unit at University College London, and colleagues wrote. “One purpose of using placebo in these studies was to avoid confounding bias due to risk compensation, which occurs if individuals perceive themselves to be protected by PrEP and so become more likely to engage in riskier sexual practices.

Sheena McCormack

“Our findings refute concerns that the effectiveness of PrEP would be compromised in a real-world setting.”

McCormack and colleagues conducted their open-label, randomized controlled trial at 13 sexual health clinics in England. Adult MSM without HIV who reported unprotected anal intercourse in the previous 90 days and anticipated further unprotected anal intercourse were randomly assigned daily Truvada (emtricitabine, tenofovir disoproxil fumarate, Gilead Sciences) either at enrollment or after a 1-year deferral period. Participants were asked to attend a clinic every 3 months for HIV, sexually transmitted infection and hepatitis C virus testing. They also maintained daily diaries and monthly questionnaires about sexual behavior and PrEP adherence.

Between Nov. 29, 2012 and April 30, 2014, 275 MSM were enrolled to the immediate treatment group and 269 to the deferred group. The median age of participants was 35 years, 30% lived with a partner, and 64% had been diagnosed with an STI in the previous 12 months. On Oct. 13, 2014, PrEP-naive participants in the deferred group were offered treatment due to a significantly increased risk for HIV infection detected by a data monitoring committee. Follow-up for HIV incidence was collected after 48 weeks or at closure of the deferred group, and was complete for 94% of 259 patient-years in the immediate treatment group and 90% of 245 patient-years for the deferred group.

There were three HIV infections observed among the immediate treatment group (1.2 per 100 person-years) compared with 20 in the deferred treatment group (9 per 100 person-years; P = .0001). In addition, there were 174 prescriptions of post-exposure prophylaxis to 85 participants in the deferred group, compared with 14 prescriptions for 12 participants in the immediate group (relative reduction = 86%; P = .0001). There were no serious adverse drug reactions, and no difference in STI occurrence was seen between groups.

These positive results could negate concerns of risk compensation among PrEP recipients, McCormack and colleagues wrote, and even exceed results previously reported during placebo-controlled trials.

In the U.K., the standard of prevention is already high,” the researchers wrote. “Nonetheless, there remains a substantial burden of new HIV diagnoses in [MSM] already attending sexual health clinics and thus accessing this standard of prevention. The impressive reduction in HIV incidence in people taking PrEP, without a measurable increase in other sexually transmitted infections, is reassuring for clinical, community and public health stakeholders.” –by Dave Muoio

Disclosure: McCormack reports being named on HIV vaccine patents, with any profits going directly to Imperial College London, and that Gilead Sciences provided a grant to her institution. Please see the full study for a list of all other authors’ relevant financial disclosures.