Microbicides to Prevent Pregnancy May Come to Market Sooner Than Those to Prevent HIV Due to Logistical Difficulties in Testing
Although large-scale clinical trials are scheduled to begin soon for several microbicidal compounds, a microbicide that is effective against HIV will be available in 2007 "at the earliest" due to problems that may be "less scientific than practical," according to a report in the October issue of the Guttmacher Report on Public Policy (AGI release, 11/12). The report states that more than 55 different microbicidal compounds are currently being investigated and six of the "most promising" substances have begun or will soon begin Phase III trials. However, because a microbicide designed to protect against HIV will need to be tested in regions with an HIV prevalence of at least 5% among the general public, trials cannot be conducted in the United States and "inevitably must be conducted in the developing world." Even at an HIV prevalence level of 5% -- the lowest possible level for a Phase III trial of an HIV microbicide -- more than 11,000 women would need to be enrolled in the study, and they would need to make 120,000 clinic visits. The sheer scope of the trial is problematic, the report states, but attempting to conduct such a large trial in resource-poor areas further complicates matters. "With the exception of cancer studies, clinical trials of this scale have never been done before," Sharon Hillier of the University of Pittsburgh/Magee Women's Hospital, who is a principal investigator in one microbicide trial, said, adding that the challenges presented by such a trial are "simply mind-boggling." For this reason, some researchers have proposed first conducting trials on microbicides that are designed to prevent pregnancy and at least one STD to demonstrate "proof of concept" and establish an initial "market niche" for the products.
Pros and Cons of Contraceptive Microbicides
Trials testing microbicides to prevent pregnancy and STDs would be smaller in scale and could be completed faster. "Testing a product for the prevention of pregnancy and STDs is a much more straightforward path. As a result, these kinds of microbicides will be approved faster. And that's important to my company, my investors and the U.S. market, all of which cannot wait the years required to conduct HIV efficacy trials," Anne-Marie Corner, president and CEO of Biosyn, Inc., said. Kevin Whaley, director of antibody discovery for EPIcyte Pharmaceutical, added that pregnancy prevention is the "key" to gaining consumer interest in the United States, where most women do not perceive themselves to be at risk for HIV infection. He added that studies of microbicides for pregnancy prevention and HIV prevention should be conducted concurrently. However, Zeda Rosenberg, scientific director for the HIV Prevention Trials Network at Family Health International, said that microbicides that protect against HIV should be a higher priority, explaining that women in developed countries already have ways of preventing pregnancy. She said that in the developing world, "[w]omen, as compared to men, still lack the power to negotiate condom use in sexual interactions. The need for a female-controlled method of HIV prevention is the number one public health objective for most parts of the developing world -- it hasn't gone away," adding that researchers will eventually have to conduct HIV studies, "no matter what," so there is "no reason to lengthen this process by delaying those studies." Pam Norick, legislative advocate for the Campaign for Microbicide Development, said that focusing on pregnancy prevention might seem like a "broken promise" to legislators who have allocated $15 million for HIV-specific microbicide research in fiscal year 2002. "If Congress sees that the first product out of the gate is not effective against HIV, they may think we sold them a bill of goods," she explained. The House is currently considering the Microbicide Development Act of 2001 (HR 2405), which would "formally" establish microbicide research programs at NIH and the CDC, and the bill is expected to be introduced in the Senate soon (Boonstra, Guttmacher Report on Policy, October 2001).