In the 36 years since HIV/AIDS spiraled into a worldwide pandemic, killing roughly 35 million people, medical science still hasn’t been able to defeat the immunodeficiency virus. The World Health Organization (WHO) estimates that some 37 million people are living with HIV. There are 1.1 million Americans currently infected, according to the Centers for Disease Control and Prevention — and 1 in 7 of them don’t know it.
Researchers and scientists have been attacking HIV from all angles since the virus was identified. Countless trials of anti-retrovirals and various medications have succeeded at developing drug treatments that slow the growth of the virus in the body, but efforts to prevent the transmission of the virus could have the greatest impact yet.
One of the biggest breakthroughs in HIV medicine this century was the discovery of a PrEP (pre-exposure prophylactic) drug in the form of tenofovir, which can block HIV infection. This week, PrEP gained a powerful advocate when WHO included tenofovir in its updated list of essential medicines for the first time.
Tenofovir, combined with the antiviral HIV drug emtricitabine, is sold commercially as Truvada, the first prophylactic HIV drug on the market. Prophylactic drugs are unique in the sense that they are medications taken before exposure to the disease in an effort to block it ahead of time.
In a landmark multinational study called the Preexposure Prophylaxis Initiative (iPrEX), the results of which were released in 2010, researchers documented that Truvada provided 44 percent more protection against HIV among men and transgender women who had sex with men. Subsequent studies have shown even better effectiveness, with a 2015 UK study finding an 86 percent reduction in HIV when given to men in health clinics.
PrEP, says Dr. Susan Buchbinder, one of the authors of the original iPrEX study, “really is an essential tool for HIV prevention and for controlling the epidemic.” Buchbinder is the director of Bridge HIV, an HIV prevention research group in the San Francisco Department of Public Health.
“I think it’s fantastic,” Buchbinder remarked to Seeker of the WHO announcement. “PrEP has the potential for really substantively affecting the HIV epidemic.”
The WHO list of essential medicines first launched in 1977 as a guideline for international health policies. The organization characterizes this catalog of core medications, which tenofovir has joined, as “a list of minimum medicine needs for a basic health-care system.”
But while WHO’s guidelines carry a lot of weight in the world of public health, they are ultimately little more than suggestions. There has been no word yet on whether this announcement will impact policy in the United States. In the weeks ahead of the WHO announcement, Belgium, Brazil, and Portugal each declared initiatives to provide greater access to PrEP through their health services.
Truvada is currently available only by prescription in the US, and carries a stigma as well as a hefty price tag. Controversies have swirled around the drug since the FDA approved it in 2012. Some opponents speculate that its use encourages unsafe sex and will contribute to a rise in STDs, though this effect has not been demonstrated. In terms of price, Truvada comes in at over $13,000 for a year’s worth of pills without insurance. Most insurance companies currently cover Truvada, however, and Gilead, the pharmaceutical company that produces the drug, also offers cost assistance programs.
Though Truvada is effective, researchers are still exploring new technologies in HIV prophylactics. One idea being tested in a clinical trial is to see if PrEP can be administered in the form of a shot, making it easier for people to get the full dose of medication if they can’t adhere to the routine of taking a pill every day.
The shot form of PrEP wouldn’t be tenofovir, said Buchbinder, who is involved with that trial. Instead, they are testing another HIV medication, cabotegravir, and hope that the shot may provide protection for several months at a time. They are currently in the middle of a phase three clinical trial, and expect results within the next couple of years.
Other current studies in PrEP include trials that are studying the prophylactic effects of monoclonal antibody infusions. This solution could be particularly useful since it would eliminate the possibility of drug resistance. Researchers are also looking at ways to deliver PrEP medications through a variety of devices, including gels and rings.
PrEP is essential, Buchbinder said, but the real holy grail of HIV research remains a vaccine.
“Ultimately,” she said, researchers want to find “an active vaccine strategy that could be used in infancy so that everyone is protected against HIV.”