Microbicide trial results signal end of one chapter, focus turns to promising ARV-based candidates

Microbicide trial results signal end of one chapter, focus turns to promising ARV-based candidates

While acknowledging disappointment in the trial results announced today, the Global Campaign for Microbicides noted that the failure of PRO 2000, a candidate microbicide gel, to show effectiveness against HIV was only the “end of the beginning” in the search for a safe and effective product. This comment came in response to the UK-based Microbicides Development Programme’s announcement that its MDP 301 trial, which enrolled over 9000 women in four African countries, has shown conclusively that PRO 2000 was safe but did not reduce women’s risk of acquiring sexually-transmitted HIV.

Microbicides are being developed as products that could be topically applied by a receptive sex partner to reduce risk of becoming HIV infected during sex. Microbicide candidates are being formulated as vaginal gels, suppositories, foaming tablets or slow-releasing vaginal rings.

Last February, the release of promising results from another PRO 2000 study, HPTN 035, signaled that PRO 2000 might be effective—a hope that was disproven by the MDP 301 results. “We all knew that the trend observed in HPTN 035 could have been due to chance,” noted Yasmin Halima, Director of the Global Campaign. “While we are deeply disappointed to learn definitively that PRO 2000 is not effective, it is our responsibility as advocates to turn our full attention now to the candidates currently in clinical trials”, she continued. “These candidates, being tested as oral pills as well as microbicides, contain antiretroviral drugs or ARVs, the same life-saving medications used as treatment by people living with HIV. In laboratory and animal studies, they appear to be many times more potent than any of the non-ARV-based candidates”, she added, noting that results of the first effectiveness results from this new class of products are expected next year.

Dr. Sheena McCormack, Principal Investigator for the PRO 2000 trial, observed that adherence rates (participants’ use of the test product as directed) were high in this study. “We know that women and their partners liked the gels and used them”, McCormack stated. The trial used multiple methods to determine how frequently women were using the gel and all indicated a high level of use. “Women reported that using it increased sexual pleasure and fostered intimacy by helping women talk about sex with their partners,” McCormack added, “So we know that we have the method right. Now we just need a product with the potency to stop HIV.”

Because the MDP 301 trial featured a much stronger social science component than any previous HIV prevention trial, it has also generated a substantial body of data on sexual behaviors that can be immediately applied to existing HIV prevention research and programming. The findings, which will be published over the coming months, confirm that the majority of trial participants liked using the gel, noting it made condom use easier and more pleasurable. “We have heard this in other large-scale microbicide trials as well”, Halima added.

Samu Dube, leader of the Global Campaign’s Africa team noted that, while communities participating in the MDP 301 trial are understandably disappointed by the trial results, they are nevertheless proud to have participated in it and determined to see microbicide and other prevention research continue. “As African women, we cannot afford to feel defeated,” Dube stated. “We know that research is a painstaking process and that the challenge of finding safe and effective products is not easy. But women are engaging in the process because we must find a tool to save the lives of our daughters and sisters. Giving up is not an option for us,” she said.

Reiterating this sentiment, McCormack quoted the words of one of the South African women who volunteered for the MDP301 trial participants who said that, “[e]ven though the gel proved not to be effective, we played a role in the fight against HIV. We learnt a lot about caring for ourselves, such as using condoms. We also learnt to encourage others to test for HIV and we gained confidence in helping those who were already infected.”

Global Campaign for Microbicides is a network of advocates and nongovernmental organizations (NGOs) working to expand HIV prevention options for women and encourage ethical research that involves civil society. Since 1998, GCM has worked to accelerate product development, facilitate widespread access and use of existing tools, and protect the needs and interests of users and communities, especially women.

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