Researchers are stopping tests of a daily pill to prevent infection with the AIDS virus in thousands of African women.
The study was stopped because partial results show no signs that the drug is preventing the virus.
The study found that women taking Truvada, made by Gilead Sciences Inc., are just as likely to get HIV as other women who have been given dummy pills. Researchers said that even if the study were to continue it would not be able to determine whether the pills help prevent infection, since the results are even this far along.
Another study last fall concluded that Truvada did help prevent infections in gay and bisexual men when given with condoms, counseling and other prevention services. Many AIDS experts view that as a breakthrough that might help slow the epidemic.
Family Health International announced the new results on Monday. The nonprofit group launched the study two years ago and had enrolled about half of the 3,900 women treated in Kenya, Tanzania and South Africa. As of last week, 56 new HIV infections had occurred, half in each group.
No safety problems were seen with Truvada, but women taking it were more likely to become pregnant.
“That’s both a surprising finding and one that we can’t readily explain” by what is known so far about Truvada’s effects on women using hormonal contraceptives, Dr. Timothy Mastro of Family Health International told The Associated Press (AP).
The study was sponsored by the U.S. Agency for International Development and the Bill & Melinda Gates Foundation. Gilead provided the drugs for the study.
A study performed last year in South Africa found that a vaginal gel spiked with tenofovir cut a woman’s chance of getting HIV from an infected partner in half. Protection was greater for those who used it most faithfully.
A similar effect was seen in the study of Truvada in gay men. The drug lowered the chances of infection by 44 percent, and by 73 percent or more among men who took their pills faithfully.
Dr. Robert M. Grant of the Gladstone Institutes, a private foundation affiliated with the University of California, San Francisco, told AP that in the new study, “it’s difficult to understand why they did not see protection.”
Grant led the study of Truvada in gay men and said “we are very confident that this approach is useful” for them.
The new study’s result “must be seen as what it is “” the closure of a single trial in a field that has generated exciting results in the recent past,” Mitchell Warren, head of the AIDS Vaccine Advocacy Coalition, told AP.
Truvada costs $5,000 to $14,000 a year in the U.S. but as little as $140 a year in some poor countries where it is available in generic form.
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