Source: Business Day Live
Hopes that a South African-developed vaginal gel containing the HIV/AIDS drug tenofovir would protect women against HIV were dashed on Tuesday, after a major new study found that it did not work.
Five years ago, scientists were optimistic that the microbicide would protect millions of women from HIV, after a phase 2 study of 900 women in KwaZulu-Natal called Caprisa 004 found it reduced the risk of getting the virus by 39%. The development was hailed as a breakthrough, though the scientists who led the work were careful to emphasise that further research was needed to replicate the findings. At that stage, 11 other trials testing six other products had failed.
The Caprisa 004 findings had a wide margin of error, with the efficacy of HIV protection estimated to lie between 6% and 60%, and so the much larger Follow-on African Consortium for Tenofovir Studies (Facts) 001 trial was launched in 2011 to confirm its findings. The trial was funded by the Department of Science and Technology, the Bill and Melinda Gates Foundation and USAID.
The first hint that Caprisa 004 might not be replicated came in 2013, when the Voice (Vaginal and Oral Interventions to Control the Epidemic) trial found there was no difference in HIV infection between women who used the gel daily and women who used a placebo. It also found a very low adherence rate.
On Tuesday, the Facts scientists announced at the annual Conference on Retroviruses and Opportunistic Infections in Seattle that a tenofovir-containing microbicide provided to 2,059 women aged between 18 years and 30 years did not protect them from HIV. Half the women were given the gel while half got a dummy product, and they were instructed to use it before and after sex. Overall, there were 123 HIV infections, with 61 infections in the group that received the tenofovir gel, and 60 infections in the group that got the placebo.
Only a small proportion (22%) of the women used the gel as intended, and even in this group the product was only modestly effective, reducing the risk of contracting HIV by 52%. Between 50% and 60% of the women used the product about half the time.
"This was a critically important study to answer the question: ‘Does a coitally-dependent gel work?’ The answer is no," said Facts protocol co-chairwoman Helen Rees, who is also executive director of the Reproductive Health and HIV Institute at Wits.
"We … used new strategies (to encourage women to use the product)," but it was probably unrealistic to expect women to use the product all the time. "Women’s lives are complicated," said FACTS protocol co-chairwoman Glenda Gray.
"The Facts 001 results are disappointing, but with all scientific endeavours there is a certain amount of uncertainty in the outcome," said Centre for AIDS Research in Africa (Caprisa) director Salim Abdool Karim, who jointly led the Caprisa 004 study with his wife Quarraisha. "We have lived through more than 18 years of disappointing results in this field and so we have to move on," he said.