A Food and Drug Administration (FDA) panel is debating whether to make history by recommending approval of the first drug to prevent HIV infection.
The advisory committee is expected to vote on Thursday on whether the new indication for the drug Truvada, which has been approved since 2004 to treat people already infected with HIV, is warranted. The experts are basing their decision on groundbreaking studies conducted among gay men and heterosexual couples at high risk of becoming infected with HIV. Those trials showed that Truvada cut the risk of new infection by at least 44% in healthy gay and bisexual men when combined with condoms and counseling, and by 73% in heterosexual couples in which one partner had HIV but the other did not.
An FDA review of Truvada — a pill that combines two HIV-fighting antiretroviral drugs, tenofovir (Viread) and emtricitabine (Emtriva) — released on Tuesday ahead of the vote suggested that the drug was safe and effective for preventing HIV. It said that people at risk for HIV “may be spared infection with a serious and life-threatening illness” if they use Truvada daily along with other prevention methods. As for Truvada’s safety, the FDA said the drug “appeared to be well tolerated among HIV-uninfected individuals.”
Doctors already use Truvada off-label as a prevention tool, but FDA approval of the drug for that indication would allow its maker, Gilead Sciences Inc., to market it for that purpose. And given that an HIV vaccine is still a long way off, approval of Truvada would mark another milestone in the battle against HIV and AIDS, and for the antiretroviral (ARV) drugs that have already changed the course of the epidemic.
Physicians and AIDS advocacy groups have been divided over whether the FDA should approve the new indication. Some groups are eager to welcome another option for preventing HIV. “When a drug is safe and effective for a particular use, and there is a real need — which, in other words, is the HIV epidemic — then failing a good reason to stop people from using it, I think people have the right to access something that is safe and effective,” says Chris Collins, vice president and director of public policy of amfAR. “People need to know the potential risks and benefits, and we need to study this more, but what it comes down to is allowing people to make an informed choice on whether this can benefit them.”
However, some doctors argue that the data are not strong enough to support approval. It hasn’t been long since researchers began testing ARVs as a prevention tool in healthy patients — a strategy known as pre-exposure prophylaxis, or PrEP. It is only recently that improvements in drug development have mitigated some of the worst side effects of the medications, which initially included severe lipid imbalances, weight gain and an increased risk of certain cancers. In comparison to older ARVs, Truvada is relatively easy to take, and in the prevention trials, participants on the drug did not show a significantly higher rate of adverse effects compared to those taking placebo. Still, the follow-up for those studies only extended for several years, and some experts believe longer trials are necessary to better understand the effects of the medication on healthy people over time.
There is also little evidence to show that Truvada would actually have an impact on the incidence of HIV. Theoretically, if approved, more people might use the drug to protect themselves from infection. But there already exist well-proven prevention methods — condom use, for example, and other safe-sex practices — that haven’t quelled the epidemic yet. Some doctors note that new approval of Truvada could undercut these HIV prevention efforts.
Any approach that relies on human behavior — whether that means taking pills or using condoms — will never be as effective as they are designed to be. Indeed, in a study of Truvada to prevent HIV among female sex workers in the developing world, the drug did not protect against infection any better than a placebo; the trial was stopped early. Researchers think the drug’s failure may have been due to the fact that the participants were not taking the pill daily as required.
The drug is also expensive, costing more than $10,000 a year in the U.S., which depending on insurance coverage, could make it accessible only to a small group of people who could afford it.
But with some 50,000 new cases of HIV occurring in the U.S. each year, any new weapon against infection would be welcome, provided it is safe and effective, says Collins. Only as our anti-HIV arsenal grows will we finally have some chance of slowing the epidemic.