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Five Exciting HIV Prevention Studies We’re Paying Attention To

, by Emily Newman

science research What’s on the horizon of HIV prevention? With one drug approved for PrEP (pre-exposure prophylaxis) many people are now looking ahead and wondering what the future of HIV prevention will bring. Will it come in the form of a gel applied before or after sex? Will it be a long-acting injection? Or will it be a vaccine?

One way to anticipate what the future will bring is to keep tabs on the HIV prevention clinical trials now in process. Drugs and therapies are required to go through many rounds (or “phases”) of clinical trials to make sure they’re safe and effective. Drugs and therapies that reach later phases of testing (e.g., phase 3 studies) are those that have shown promise in earlier studies and therefore may be more likely to eventually be approved for use.

Here are five clinical trials to pay attention to, if you’re interested in what the next big breakthrough in the HIV prevention field may be.

HPTN 077: A Long-Acting PrEP Injection

Cabotegravir LA vial and syringe (Photo courtesy of David Margolis)

Cabotegravir LA vial and syringe (Photo courtesy of David Margolis)

The drug cabotegravir, an integrase inhibitor, is currently being tested as part of an every-other month, long-acting injection for PrEP. The idea is that, instead of having to take a daily pill, people would be able to go to their provider and get a shot that would offer protection from HIV for two months.

Promising results from a smaller previously completed study of the same drug formulation were presented in February 2016. The current two-year, phase 2a HPTN 077 study will assess the safety and tolerability of the drug injections among 176 HIV-negative men and women who are included in the study.  The study will compare the long-acting injection of cabotegravir (800 mg) given every 12 weeks to placebo.  Each dose of the study drug is delivered in two separate injections into the gluteus maximus muscle (the “glutes,” or butt muscle). Results are expected by the end of 2017.

HPTN 076: A Different Long-Acting PrEP Injection

Because taking a medication every day can oftentimes be a challenge for people taking PrEP, perhaps it’s no surprise that researchers are investigating more than one long-acting PrEP drug. A second drug, rilpivirine, is also being investigated as a long-acting PrEP injectable in a phase 2 study with adult HIV-negative women.

The two-year HPTN 076 study has enrolled about 132 women (88 will receive the active drug; 44 will receive placebo). The study will compare the long-acting injection of rilpivirine (1200 mg) given once every eight weeks to placebo. Each dose of the study drug is delivered in two separate injections in each gluteus maximus muscle (the “glutes,” or butt muscle). Results are expected by the end of 2017.

HVTN 702: An HIV Vaccine

This spring, the HIV community received news that a large HIV vaccine clinical trial would be conducted in South Africa towards the end of 2016. The announcement generated buzz because this is the first time in seven years that an HIV vaccine has shown enough promise to be ready for a large-scale clinical trial.

The study will test a vaccine composed to two separate compounds: A canarypox-based vaccine called ALVAC-HIV and a gp120 protein subunit vaccine. This vaccine regimen is similar to that used in the most successful study to date—the Thai RV144—which found that people who received the vaccine were 31% less likely to become infected with HIV.

Read more about why it’s been so difficult for scientists to develop an HIV vaccine on BETA.

The phase 2b/3 study—which is slated to begin enrolling at the end of 2016—will enroll 5,400 HIV-negative men and women between the ages of 18 and 35 in South Africa. Participants will be randomly assigned to receive placebo or the vaccine regimen, which consists of five injections over one year.

MTN 025 & IPM 032: A Vaginal Ring for Women

Dapivirine ring

Dapivirine ring (Photo: International Partnership for Microbicides)

Last year, the HIV community got a glimmer of hope that an HIV-prevention product designed specifically for women could be effective from results of two clinical trials called The Ring Study and ASPIRE. The product, a vaginal ring delivering the drug dapivirine, provides longer-lasting HIV protection and only needs to be replaced once per month. Although the results from these two studies looked promising, the researchers reported that there were still adherence issues—with women in the studies likely removing the ring in between study visits.

Two continuation studies—MTN 025 and IPM 032—will provide women with open-label access to the product to determine once and for all if this is a product that women at risk for HIV want to, and can, use successfully. Participants in the phase 3 studies will be provided with 25 mg dapivirine ring to be replaced once a month for a total period of 12 months. The studies will collect adherence and longer-term safety data.

HVTN 703 and HVTN 704

A little over 4,000 people in Africa and North and South America will participate in the HVTN 703 and HVTN 704 studies—phase 2 studies that will test how well a broadly neutralizing antibody called VRCO1 works to prevent HIV.

The VRC01 antibody was first discovered in the blood of an “elite controller”—a person who had HIV for many years and was able to control the virus without medication. The antibody blocks up to 90% of HIV strains, which is why it is called “broadly neutralizing.” Thus far, the VRC01 therapy has been effective in preventing HIV-like infections in studies with monkeys and was well-tolerated by human participants in a small study.

The current studies will test whether an intravenous (IV) infusion of VRC01, delivered once every eight weeks, will prevent HIV infection in women (HVTN 703) and men who have sex with men and transgender people (HVTN 704). Participants will enroll in the studies for approximately two years, and complete results from the studies are expected by 2022.

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