The US Food and Drug Administration (FDA), announced on Monday that it has approved a existing drug, Truvada for reducing risk of infection by sexually transmitted HIV-1 in adults. This is the first drug the FDA has indicated for uninfected adults at high risk of acquiring HIV through sex. HIV-1 is the most common form of the human immunodeficiency virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS).
Agency experts say Truvada, produced by Gilead Sciences Inc, should be used in combination with safe sex practices. The once-daily oral medication is a combination of two antiretroviral drugs used to treat HIV: tenofovir disoproxil fumarate and emtricitabine.
The data supporting the approval of Truvada for HIV prevention in uninfected adults, a strategy called pre-exposure prophylaxis (PrEP), comes primarily from two large placebo-controlled trials that showed taken once daily, the drug significantly reduced the risk of HIV infection in uninfected adults at high risk of acquiring the virus through sex.
One trial, called Pre-Exposure Prophylaxis Initiative (iPrEx), involving about 2,500 HIV-negative gay and bisexual men and transgender women, showed the drug reduced risk of HIV infection by 42%. That trial was sponsored by the US National Institutes of Health (NIH) and the Bill and Melinda Gates Foundation.
The other trial, called Partners PrEP, involving about 4,800 heterosexual couples where one partner was HIV positive and the other was not, found the drug reduced risk of infection by 75%. That trial was sponsored by the University of Washington and funded by the Bill and Melinda Gates Foundation.
Connie Celum, Professor of Global Health and Medicine at the University of Washington and lead investigator of the Partners PrEP trial, said:
"The data clearly demonstrate that Truvada as pre-exposure prophylaxis is effective at reducing the risk of HIV infection acquired through sexual exposure." Several other studies also support the use of Truvada for HIV risk reduction.
In all trials of Truvada for PrEP, the most commonly reported adverse events were headache, stomach upset and weight loss. The frequency and types of side effects are similar to use of the drug for HIV treatment, which now has a history of four million years of patient use. Altogether, treatments containing tenofovir, add up to nine million patient years of experience.
New Use of An Existing Drug
Truvada, currently the most-prescribed antiretroviral in the US, was approved in 2004 in combination with other antiretrovirals, to treat HIV-infected adults and children over 12 years old. The drug works by stopping HIV from establishing itself and multiplying in the body.
Debra Birnkrant is director of FDA's Division of Antiviral Products. She told the press thanks to medical advances, and the availability of nearly 30 approved individual HIV drugs, we can now treat the infection as a chronic disease most of the time, instead of the life-threatening disease we used to view it as in the 80s and 90s.
"But it is still better to prevent HIV than to treat a life-long infection of HIV," she said.
Safe use of Truvada for HIV Prevention
Gilead and the FDA have produced a Risk Evaluation and Mitigation Strategy (REMS) to help ensure safe use of Truvada for PrEP.
The REMS materials aims to educate and inform uninfected patients and their doctors about how to use Truvada for HIV prevention.
They point out Truvada for PrEP should only be used by HIV-negative patients, and emphasize the importance of sticking strictly to the dosing regimen and of understanding the drug should only form one part of a comprehensive strategy to prevent HIV-1 infection. They also note that treatment should not be initiated when clinical signs or symptoms consistent with acute HIV-1 infection are present.
The comprehensive strategy includes consistently using condoms correctly, receiving counseling for risk reduction, regular HIV tests every three months, and being treated for other sexually transmitted diseases.
The drug is not a substitute for safer sex practices, said Birnkrant.
In a press statement, Gilead has announced the company will issue vouchers for free HIV tests and condoms, and provide an opt-in service that sends regular reminders about HIV testing. It will also subsidize HIV resistance testing for anyone who becomes HIV-positive while taking Truvada for PrEP.
The company also announced that, based on the iPrEx trial results, in January 2011, the US Centers for Disease Control and Prevention (CDC), issued interim guidelines on how to use Truvada as PrEP among high risk men who have sex with men.
The CDC is in the throes of developing formal guidelines for use of the HIV prevention drug with men and women. These will include procedures for HIV testing and health screening prior to treatment, as well as ongoing surveillance of cases of infection that may arise despite use of the drug, monitoring of any drug resistance among those who become infected, as well as side effects and clinical toxicities.
Patient Must Be HIV-Negative
In their press announcement, the FDA emphasize the importance of ensuring Truvada as PrEP is only given to patients who are HIV-negative. This is because when the drug is used to prevent HIV, the patient must also take a third drug, so the treatment is not the same as for a patient who is already infected.
Which of the other approved HIV drugs is taken with Truvada depends on the patient, said Birnkrant.
Also, before prescribing Truvada as PrEP, doctors must consider with their patients a number of factors in order to weigh the risks against the benefits, said Birnkrant. These include:
The patient must undergo an HIV test to ensure he or she is HIV-negative.
The patient must not have flu-like symptoms: these are a "red flag" because they could be early signs of acute HIV infection, even if the test is negative. It takes time for the antibodies that indicate HIV infection to appear in the blood and in the meantime they won't be picked up in a test.
The safety concerns about Truvada are linked to effects on bone and kidneys. Although evidence from trials suggest these are mild and reversible once medication ceases, people with a history of bone or kidney problems should have regular monitoring if they take the drug.
Patients should also undergo tests for hepatitis B, because these infections can worsen in patients who are co-infected with HIV-1 and hepatitis B when medication with Truvada ceases.