Lack of Success Terminates Study in Africa of AIDS Prevention in Women

Early data showed no evidence that the pill was working.

Women taking the medication, Truvada, were just as likely as those taking a placebo to become infected, according to an independent panel that analyzed the results after the study had enrolled about half the 4,000 women researchers had hoped to enlist.

Of the 1,900 women taking Truvada or a placebo, 28 in each group had become infected as of last week, according to FHI, formerly Family Health International, the nonprofit group that was conducting the study in South Africa, Kenya and Tanzania.

“It’s surprising, disappointing and frustrating,” said Mitchell Warren, executive director of AVAC, an advocacy group for AIDS prevention in New York. “But there’s a strong rationale for continuing other trials in women in hopes of obtaining better results in the future.”

Two other studies of what is called “pre-exposure prophylaxis” in women are still under way in Africa. The results are expected over the next two years.

The inconclusive results of the latest trial are a surprise to many experts. A study published last November found that Truvada protected gay men against infection. Men who took their pills faithfully were shown to have better than 90 percent protection, a result hailed as a breakthrough for AIDS prevention.

And results published last summer from a trial in South Africa showed that a vaginal gel containing tenofovir, one of the two antiretroviral drugs in Truvada, reduced the chances of infection by 54 percent in the women who used it faithfully before and after sex.

Because the current study — known as FEM-PReP on the list of catchy acronyms scientists use to distinguish many similar trials from one another — was stopped early and abruptly, many questions about it remain.

One is whether there was any difference in how often the women given Truvada and those given a placebo actually took their pills. More women taking Truvada complained of unpleasant side effects, and therefore a greater number might have failed to adhere to the program.

The researchers asked the women every month how often they took their pills, but preferred to confirm those answers through blood samples. The samples are in storage and have not yet been analyzed.

After that is done, “we might be able to get a better handle on the adherence,” said Dr. Timothy Mastro, vice president for health and development sciences of FHI.

Any woman who became pregnant was removed from the study, because Truvada has not been proved safe for pregnant women; for unknown reasons, more women taking the medication became pregnant, which may also have skewed the early results.

Another question is how much Truvada infused the walls of the vagina, where the initial infection takes place.

According to Dr. Robert M. Grant, a California AIDS researcher who led the study of Truvada in gay men, other research has shown that vaginal gels are as much as 100 times more effective than pills at getting protective antiretroviral drugs into the vaginal walls. Pills and gels are about equally effective in getting them into rectal tissue, he said.