Promising Drug to Prevent HIV Fails in Trial–But It's Not Out of the Picture

By Veronique Greenwood | April 19, 2011 3:23 pm

UPDATE: The blood tests are in, and it looks like the women instructed to take the pills were not popping them. Only a quarter of those who got infected had any Truvada in their blood. This suggests that the problem isn’t the drug’s effectiveness, but rather compliance on the part of the population.

What’s the News: A much-anticipated trial in African women of an HIV drug found to be effective in preventing infection in men has washed out—researchers announced today that women taking Truvada were no more likely to evade HIV infection than women taking a placebo.

The result is especially disappointing because Truvada, which is an oral pill combining two drugs, emtricitabine and tenofovir disoproxil fumarate, has been shown to be 90% effective in preventing infection in gay men who took it religiously.

What’s the Context:

  • Truvada, made by Gilead Sciences, is also used to treat patients with HIV, but researchers have been testing whether it can also prevent infections.
  • The trial, which was run by FHI, a North Carolina–based nonprofit, was investigating whether Truvada could be effective in an oral form for women. HIV prevention measures that a woman can take orally or apply before sex stand a greater chance of being effective than those that are dependent on male partners’ compliance.
  • Why the drug failed is not clear: researchers are not sure whether this indicates that the drug is not effective in oral form in women, or whether some other aspect is at play.

Not So Fast: The study’s results haven’t been published yet–these results were announced by FHI in a press release. Analysis of the study data may show that adherence to the drug regimen, rather than the drug itself, is at fault. The investigators asked subjects whether they had been taking the drug, which must be taken every day, but they also took blood samples in order to confirm it. Those samples haven’t been analyzed yet, so it’s possible that Truvada’s apparent lack of effect is due to the women not taking it as they should.

The Future Holds: Elsewhere in Africa, clinical trials of the drugs in Truvada are continuing. One trial focuses on the effect of the combined drugs or tenofovir alone on the uninfected partners of infected people; the other trial includes a tenofovir gel in addition to those oral treatments and is following 5,000 women in sub-Saharan Africa. The current trial’s failure is far from the end for Truvada.

CATEGORIZED UNDER: Health & Medicine
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