Studies Show Progress in Finding New HIV Prevention Options and Implementing Existing Approaches

Researchers released data from five cutting-edge studies that show progress across several major HIV prevention approaches at an official press conference at the 9th IAS Conference on HIV Science (IAS 2017). These included new insight on the effectiveness of on-demand pre-exposure prophylaxis (PrEP), progress in developing a long-acting PrEP option, health benefits to female partners of circumcised men, effectiveness of treatment as prevention among gay male couples and new strategies to increase HIV testing among female sex workers.

"We're in an era of unprecedented progress in HIV prevention science," Linda-Gail Bekker, the President of the International AIDS Society (IAS) and International Scientific Chair of IAS 2017, said. "The research released today is helping discover new HIV prevention options and also providing a deeper understanding of how to use the tools we already have."

The press briefing highlighted the following five HIV prevention studies, which were selected from more than 1,700 scientific abstracts being presented at IAS 2017.

On-demand PrEP remains highly effective in MSM having less frequent sex:
A new subgroup analysis of the IPERGAY trial found that an on-demand PrEP regimen of tenofovir plus emtricitabine (TDF/FTC) remained highly effective among men who have sex with men (MSM) who had less frequent sex and used fewer pills than the trial's original overall study population.

Guillemette Antoni of the French National Institute of Health and Medical Research (Inserm) reported the results, which included MSM who "systematically or often" used PrEP during sex (median of five sex acts per month) and took 15 or fewer pills per month. In this subgroup, there were no infections in the TDF/FTC arm and six infections in the placebo arm.

The original IPERGAY trial results, announced in 2015, showed that on-demand PrEP reduced HIV risk among study participants by 86%. However, on average, participants in that trial engaged in more frequent sex (median of 10 sex acts per month) and took more PrEP pills (median of 15 pills per month). [Summary based on submitted abstract; updated data may be presented on site.]

Abstract: On-demand PrEP with TDF/FTC remains highly effective among MSM with infrequent sexual intercourse: a sub-study of the ANRS IPERGAY trial
Session: Updates from PrEP Clinical Trials (Blue Amphitheatre, Tuesday, 25 July, 11:00-12:30)

Promising results for an investigational long-acting HIV prevention option:
A new study found that pharmacokinetics support the exploration of cabotegravir for HIV prevention, using 600mg injections every eight weeks following a four-week loading dose.

Raphael Landovitz of the University of California, Los Angeles, reported results from HPTN 077, a Phase IIa, randomized double-blind placebo-controlled trial of a long-acting injectable form of cabotegravir (an integrase inhibitor) in low-risk, HIV-negative adults. The study enrolled 199 men and women in Brazil, Malawi, South Africa and the United States.

First, participants received a "loading dose" consisting of 30mg of the study drug, taken orally every day for four weeks. Then, one study group received 800mg injections of the drug at weeks 5, 17 and 29, while the other group received 600mg injections on a more frequent schedule: weeks 5, 9, 17, 25 and 33. The study drug was well tolerated in both groups, but only the second group consistently achieved targeted levels of the drug in their blood. [Summary based on submitted abstract; updated data may be presented on site.]

Abstract: Safety, tolerability and pharmacokinetics of long-acting injectable cabotegravir in low-risk HIV-uninfected women and men: HPTN 077
Session: Updates from PrEP Clinical Trials (Blue Amphitheatre, Tuesday, 25 July, 11:00-12:30)

Male circumcision associated with lower prevalence of HIV, some STIs among female partners in South Africa:
Based on data from 4,766 female participants, a new study found that partner circumcision was associated with decreased prevalence of herpes simplex virus-2 (HSV-2) in all women, decreased HIV prevalence in younger women, and decreased syphilis prevalence in older women.

Previous research has shown that circumcision partially protects men from acquiring HIV and some sexually transmitted infections (STIs) through heterosexual sex. Studies also suggest that female partners receive some protection, perhaps indirectly because of lower prevalence of infection among men. However, there has been a lack of population-level data outside of experimental settings.

This study, presented by Ayesha Kharsany of the Centre for the AIDS Programme of Research in South Africa (CAPRISA), uses data from South Africa's HIV Incidence Provincial Surveillance System to examine the association between HIV and STIs and partner circumcision among women in uMgungundlovu District, South Africa. The study concluded that male circumcision provides community-level protection against HIV and some other STIs among women. [Summary based on submitted abstract; updated data may be presented on site.]

Abstract: Association between HIV and sexually transmitted infections and partner circumcision among women in uMgungundlovu District, South Africa: a cross-sectional analysis of HIPSS baseline data
Session: Prevention: It's Not Just about PrEP (Blue Amphitheatre, Tuesday, 25 July, 14:30-16:00)

Strong evidence that undetectable viral load prevents HIV transmission among gay male couples:
While the landmark HPTN 052 study found clear evidence that undetectable viral load significantly reduces HIV transmission among heterosexual HIV-serodiscordant couples (i.e., one partner is HIV positive and the other is HIV negative), to date there has been limited prospective data on the association of HIV transmission and undetectable viral load in male HIV-serodiscordant couples.

Andrew Grulich of the University of New South Wales in Australia reported results from the Opposites Attract cohort study, which enrolled 358 male serodiscordant couples in Australia, Thailand and Brazil. At baseline, 79.9% of the HIV-positive partners were on antiretroviral treatment and 77.9% had an undetectable viral load.

Over the course of the study, the researchers found no linked HIV transmissions despite nearly 17,000 acts of condomless anal intercourse, indicating that undetectable viral load prevents HIV transmission among homosexual men. [Summary based on submitted abstract; updated data may be presented on site.]

Abstract: HIV treatment prevents HIV transmission in male serodiscordant couples in Australia, Thailand and Brazil
Session: The Key to Key Populations (Bordeaux Amphitheatre, Tuesday, 25 July, 14:30-16:00)

HIV self-tests for sex workers increases testing uptake, rapid linkage to care:
While an HIV test in itself cannot prevent HIV, knowledge of one's status is the first step to help stop the spread of HIV. Catherine Oldenburg of the University of California, San Francisco, shared the results of a randomized controlled trial in Zambia suggesting that HIV self-testing should be a core element of a comprehensive HIV prevention strategy for female sex workers.

The trial included 965 female sex workers who were randomized into one of three groups. The first group received oral HIV self-tests directly from a peer educator; the second group received a coupon to get a self-test from a clinic or pharmacy, and the third group received a referral to standard HIV testing. The results showed that direct provision of HIV self-tests via peer educators led to high HIV testing uptake and rapid linkage to care, including among women who had never been tested before. [Summary based on submitted abstract; updated data may be presented on site.]

Abstract: HIV self-testing among female sex workers in Zambia: a randomized controlled trial
Session: Just Do It Yourself: Preferences and Performances of HIV Self-testing (Bordeaux Amphitheatre, Monday, 24 July, 11:00-12:30)