How To Use Pre Exposure Prevention

Transcription

1 What is PrEP, or Pre-Exposure Prevention? JULY 2011

2 What is PrEP? An HIV-negative person would use PrEP by taking certain HIV medicines daily (in either a pill or microbicide) to help him or her prevent getting the virus. Currently, PrEP is being studied in various communities internationally to see if it is safe and effective at reducing HIV infection in people at high risk. Currently, two combinations are used: tenofovir (Viread) alone and tenofovir + emtricitabine (Truvada). Why is PrEP important to study? Although prevention strategies such as condom use, sero-sorting, abstinence and monogamy as well as increased testing have reduced the number of infections worldwide, more than 3 million people become infected each year. The rate of new infections remains high even in places that promote 100% condom use. At 56,300 new infections yearly in the US, this number remains flat, an indication that new prevention interventions need to be proven effective and implemented. Several monkey studies have shown that using HIV drugs significantly reduced the number of infections. The monkeys were given HIV drugs, and then exposed vaginally or rectally to SIV (the monkey form of HIV). These results provided the basis for studying PrEP in humans. What is iprex? iprex stands for the Pre-Exposure Prophylaxis Initiative. It is the first of 8 international double-blinded studies (no one knows who s taking which regimen) that are looking at using various drug regimens and microbicides in different populations at high risk for HIV infection. These populations include What is PrEP (Pre-Exposure Prevention)?

3 men who have sex with men (MSM), injection drug users, mixed status couples, and heterosexual men and women. On November 23, 2010, researchers released data from iprex. This two-year study followed 2,499 high-risk MSM and trans-women at 11 sites in the US, Brazil, Ecuador, Peru, South Africa and Thailand. Average age was 27, and 3 out of 4 were Latino/Hispanic. High-risk behavior included unprotected anal sex (60% within last 3 months), partners of unknown or HIV-positive status (77% within last 6 months) and high rate of alcohol use (54% at 5 or more drinks per day). Everyone was tested twice for HIV before starting the study. Half took Truvada once a day, while the other half took a placebo. Everyone received free condoms, intensive safer sex and adherence counseling, and routine medical care that included ongoing HIV testing and monitoring of side effects and drug resistance. All were told that using Truvada in this way is experimental and may not protect them from getting HIV. At monthly study visits, antibody tests and other blood work were done to assess HIV status and adherence through drug levels in blood. Pills were counted at each visit to assess adherence as well. What are the iprex results and what do they mean? The results showed an overall reduction in HIV infections of 44% in those who took Truvada. When looking at those who reported taking PrEP more than half the time, the risk for infection fell by 50%. When looking only at those who reported taking PrEP more than 90% of the time, the risk fell by 73%. Although participants reported taking their regimen more than 93% of the time, the actual adherence rate was around 51%, which was confirmed by measuring drug levels in blood at regular visits. In fact, Truvada was detected in only 9% of those became infected but in 51% of those who stayed negative. The What is PrEP (Pre-Exposure Prevention)? 1

4 researchers hypothesized that if all participants had taken every dose of PrEP, the rate of HIV infections could have dropped by 92% or more. A total of 110 participants became HIV-positive during the study: 10 at the start of the study, who were not known to have HIV despite taking antibody tests, and 100 others of whom 64 took placebo while 36 took PrEP. Of those 100 men, none showed drug resistance to either drug. Of the 10 men with undiagnosed acute infection, three showed resistance to emtricitabine, though not tenofovir. One had transmitted resistance, one developed resistance while on PrEP, and one had low viral load at study entry for a resistance test to be done. Truvada was generally well tolerated, though more who took the pill had more nausea and higher levels of certain blood proteins that refer to kidney damage. If anyone had stopped Truvada due to kidney concerns, all were able to see their blood proteins go back to normal. However, given the low level of adherence in the study, the actual rate of side effects could be higher if more people had taken the pill as prescribed. What do the results NOT mean? First, this study was done in high-risk men and trans-women who have sex with men. We do not know if using PrEP in this way would have the same results in other groups, such as injection drug users or women. Second, the results from this highly controlled study may not relate equally to the real world. Third, a lower risk for infection appears to apply more to the receptive partner during anal sex than to the insertive partner. Fourth, and probably most importantly, do not try taking PrEP on your own. This study was done with intensive safer sex and adherence counseling along with more frequent health care visits for blood work. Some individuals may not be able to achieve these aspects of taking PrEP outside the influence of 2 What is PrEP (Pre-Exposure Prevention)?

5 this study. Disco dosing of Truvada, or taking the pill before/ after random sexual activity, has not been proven to be effective and could actually increase a person s risk for HIV. If a person wants to take PrEP, s/he should contact their doctor and start the conversation. What will happen now after these results? Certain pilot projects will be done in high-risk communities around the country to gather more information on PrEP s effectiveness and figure out the best way to make PrEP available. This will probably take a couple of years. In the meantime, those interested in taking PrEP should talk to their doctors about it, including more regular doctor visits, HIV testing and counseling. Why use Truvada as the PrEP regimen? The two drugs in Truvada, tenofovir and emtricitabine, have been used by tens of thousands of people in studies worldwide for treating HIV. Side effects from this combination, first approved in 2004, are generally mild for most people and can include rash, nausea, vomiting, diarrhea and flatulence. Some people will experience few or no side effects, while others may have mild to moderate or severe side effects. They generally improve after the first few weeks of taking a new drug. PrEP has shown to be safe in studies so far. However, if side effects become too much for individuals to handle, then they could stop their regimen and withdraw from the study. An earlier West African study in 936 HIV-negative women showed that tenofovir was well tolerated with no increased risk of serious side effects. Other studies report that less than 1% who took Truvada quit the studies due to side effects. However, some HIV-positive people who have used tenofovir What is PrEP (Pre-Exposure Prevention)? 3

6 for treatment have reported some bone loss and kidney problems. Therefore, using Truvada may present concerns for some people, who should be monitored for any signs of these issues. There are concerns for people who have hepatitis B since the drugs in Truvada are effective for both diseases. What about HIV drug resistance? One concern with using PrEP is that if a person becomes infected while taking these HIV drugs, the virus may become resistant to them. Although two drugs are being studied to prevent HIV, it s standard to use three drugs to treat HIV infection. Therefore, a newly infected person on PrEP might see his/her HIV become resistant to either or both drugs. This means they couldn t be used later in the actual regimen for treating their HIV infection. However, earlier studies show that it s more difficult for HIV to become resistant to this drug combination than other HIV drugs. In animal studies, monkeys that were given tenofovir and became infected did not show drug resistance, which may or may not be the same for humans. (Refer to the section above, What are the iprex results? for more information on resistance.) What if a person becomes HIV-positive while taking PrEP? The iprex study s PrEP regimen may be stopped, whether it s the Truvada or placebo. Study doctors will confirm that the person is positive with a PCR viral load test. Other medical care will also be provided to assess their options which may include starting a full HIV regimen. 4 What is PrEP (Pre-Exposure Prevention)?

7 Does PrEP increase risky sexual behavior? As seen in similar studies leading up to this one, PrEP does not appear to increase risk behavior. As an example, a West African study in HIV-negative women taking tenofovir daily found that their risk behavior had actually decreased during the study. This was likely due to the counseling provided in the study. However, there may be a difference in risk behavior in these studies vs. what s found using PrEP in the real world. In iprex, the study did not report increased risky sexual behavior. Overall, participants reported lower risky behavior with fewer sexual partners and increased condom use over the course of the study. (However, self-reporting behavior in many studies is not to be the most accurate way to document a person s actual behavior.) How much will PrEP cost? It is unknown what the cost of PrEP will be. Since Truvada has not been approved by the FDA for PrEP, using it this way is considered off-label use. Therefore, it s unknown how PrEP would be covered through insurance or federal programs, if at all, although early reports look like the FDA will eventually allow this off-label use. The current cost of Truvada for treating HIV infection runs about $14,000 per year. HELPFUL RESOURCES New England Journal of Medicine iprex Website AIDS Vaccine Advocacy Coalition Help Fight HIV.org What is PrEP (Pre-Exposure Prevention)? 5

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