Heartbreak in HIV Prevention

My emotions have yo-yo’d up and down in the last year with the results of two landmark HIV prevention clinical trials. This inconsistency makes me worried that funders will lose interest in the fight against HIV at a time when high levels of funding are still needed to fund costly, but necessary, clinical trials.

Only five months ago the HIV field was ecstatic when the results of the first clinical trial of Pre-Exposure Prophylaxis (PrEP – an approach of taking a pill with the drug Truvada daily to prevent HIV infection) called iPrEX found that healthy gay men on the treatment were 44% less likely to get infected with HIV than those taking a placebo. My colleague, David Zapol, blogged about these exciting results last November. Experts in the field naturally extrapolated on these results and began to see a future where heterosexual women (the largest growing population of new infections in Africa) and others could be protected from this stigma-ridden and debilitating disease. We were waiting with baited breath for the clinical trial results from testing the same drug and daily dosage as iPrEX on heterosexual women (FEM-PrEP) to provide similar results.

We have to wait no longer. Last Monday, FHI decided to discontinue FEM-PrEP after its Independent Data Monitoring Committee (IDMC) determined that the trial would not be able to answer the question of whether the study drug decreased risk of HIV infection among HIV-negative women via sexual transmission. Mitchell Warren, Executive Director of AVAC (and close friend of FSG), said “Today’s announcement about the FEM-PrEP study is disappointing. However, it 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. Even with this finding, there is still a strong rationale for continuing other trials, including those in women, in hopes of obtaining better results in the future.”

What happened? Was it adherence issues? Participants self-reported 95% adherence to the study product, but FHI has yet to verify these numbers. Or, as TIME's "Healthland" blog writes, was it due to a physiological difference in how men and women acquire HIV, such as the difference in tissues involved during sexual conduct? Or a different, unknown reason? And why did women taking Truvada have higher pregnancy rates than those randomly assigned to the placebo arm?

All hope it not lost – Two other ongoing trials in sub-Saharan Africa are evaluating PrEP among heterosexuals. The VOICE trial is focused on heterosexual women and Partners PrEP is testing the HIV-negative member of couples in which one partner is HIV-infected.

The results of FEM-PrEP, while disappointing, should be considered knowledge gained about HIV prevention that will help the field hone its efforts moving forward. Once FHI finalizes its findings and determines the primary cause of the lack of effect in HIV-negative heterosexual women, then future trials can incorporate this knowledge when developing protocols for new clinical trials.

It’s clear that a silver bullet for HIV prevention is not just right around the corner and research will require continued and consistently high levels of funding. The US government recently released funding figures for programs in its Global Health Initiative. While the president has requested greater funding for 2012, Congress has yet to approve it. More importantly, the amount is less than the field needs and hoped for.

At a time where global funding is extremely tight in all areas, including R&D for HIV, how will these results affect momentum and future funding commitments from countries and multilaterals?

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