An Interview with PrEP Researcher, Dr. Albert Liu

In 2012, the U.S. Food and Drug Administration (FDA) approved Truvada for use in HIV prevention, a strategy known as pre-exposure prophylaxis, or PrEP. Bridge HIV’s Director of HIV Prevention Intervention Studies, Dr. Albert Liu, answers your questions about this important HIV prevention strategy.

What is PrEP and why do we need it?
Pre-exposure prophylaxis, or PrEP, involves HIV-negative people using anti-HIV medicines in order to prevent HIV infection. Several studies have shown that daily oral Truvada, a drug commonly used to treat HIV infection, is safe and effective in preventing HIV in different populations at risk for acquiring HIV infection. Based on these studies, the FDA approved Truvada for use as PrEP in combination with other prevention strategies.

This was an exciting development because we need more tools to fight HIV. Despite great advances in treatment and prevention there continues to be a significant number of new HIV infections. Because current prevention strategies may not work for everyone, it’s important for us to continue to innovate and find new strategies to fight the epidemic.

PrEP sounds a lot like PEP. What’s the difference between the two?
PEP, or post-exposure prophylaxis, is a 28-day course of anti-HIV medication started within 72 hours after an exposure to HIV that may help prevent infection. PrEP involves HIV-negative people starting anti-HIV medicines before a potential exposure and continuing it on a daily basis. PrEP may be a useful strategy to consider for people who require multiple courses of PEP.

A lot of people are understandably concerned about side effects and other risks. Is PrEP safe?
Studies in HIV-negative individuals have shown Truvada to be generally safe and well-tolerated. The most commonly reported side effects were nausea and other gastrointestinal symptoms. These symptoms often get better or go away as the body gets used to the medication. In a small number of PrEP users Truvada can cause kidney problems. In PrEP studies, these kidney problems went away after Truvada was stopped. So it’s important for people taking PrEP to have their kidney function and overall health monitored by a clinician.

Should everyone be taking PrEP? Who is it for?
PrEP is definitely not for everyone but may be useful for men and women who are at risk for HIV infection and are open to taking a daily pill to prevent HIV. Additional studies will help us understand who will be interested in taking PrEP and how to best prioritize PrEP in different populations to prevent the largest number of infections.

How about serodiscordant couples, or couples where one partner has HIV and the other is HIV-negative?
PrEP may be useful for HIV-negative individuals who have an HIV-positive partner. There was a study that showed that PrEP reduced HIV infection in heterosexual serodiscordant couples in Africa by 67-75%. We have also learned that treating the HIV-positive partner dramatically lowers the risk of HIV transmission to the HIV-negative partner. Individuals in serodiscordant relationships should discuss PrEP and other prevention strategies with their clinical provider.

If someone is taking PrEP, does that mean they don’t need to use condoms?
PrEP is likely to provide the greatest protection when used in combination with condoms and is
recommended as part of a comprehensive prevention package which also includes risk reduction counseling, regular HIV and STD testing, and linkages to prevention services. Also, PrEP doesn’t protect against other sexually transmitted diseases, such as syphilis and gonorrhea. However, PrEP may provide some level of protection against HIV when used without condoms. We’ve heard from folks who take PrEP that they appreciate how it gives them an extra layer of protection.

What are other challenges and issues people should know about PrEP?
One really big issue is adherence. For Truvada to work as PrEP it has to be taken regularly. Another issue is whether HIV resistance can develop with the use of PrEP. So far, it appears that resistance occurs when people who are already HIV-infected begin taking PrEP. Therefore, it’s very important that people are tested and evaluated by a clinician to make sure they are HIV-negative before starting PrEP. Other issues include finding out who wants PrEP and how best to deliver PrEP to people who need it most. Finally, just as a one-size-fits-all approach doesn’t work with HIV prevention strategies, we also need to find other PrEP options, as one PrEP drug won’t work for everyone.

Can you talk about ongoing and upcoming research on PrEP?
Bridge HIV has participated in several PrEP studies enrolling men who have sex with men (MSM), including Project T (a safety study of daily oral tenofovir) and the landmark iPrEx study, which showed that daily oral Truvada® is safe and effective for HIV prevention in MSM. The results from the iPrEx study supported the FDA approval of PrEP in 2012.

More recently, Bridge HIV has led efforts to test strategies to expand the use of PrEP in different communities and settings. We conducted The Demo Project, a PrEP demonstration project evaluating the delivery of PrEP in STD clinics and a community health center in 3 US cities. We are also collaborating with several local clinics to conduct the Stay Study, a PrEP demonstration project among transgender people in the San Francisco Bay Area.

As taking a daily pill may not suit everyone, Bridge HIV is also conducting studies to test new PrEP drugs and formulations. We participated in the HIV Prevention Trials Network HPTN 069 study testing the safety of a new oral PrEP medication, maraviroc, in MSM, and the Microbicide Trials Network MTN 017, testing a tenofovir gel applied rectally among MSM and transwomen. Were also involved in several vaginal ring studies, such as MTN 028, in healthy, HIV-negative women.

There has been a lot of interest in a long-acting, injectable form of PrEP which can be given every 1–2 months. Bridge HIV is currently involved in several injectable PrEP studies including HPTN 077, a study evaluating the safety of the injectable medication cabotegravir among HIV-negative men and women, and HPTN 083, a larger study evaluating the safety and efficacy of cabotegravir compared with daily oral Truvada® in 4,500 MSM and transgender women.

April 2013 / Updated December 2017