Washington Editor

Public and private backing, to the tune of $24 million, is being poured into the late-stage development of a vaginal microbicide candidate to prevent the transmission of HIV/AIDS.

Run by a non-profit organization called CONRAD, the program is aimed at determining if a gel consisting of 6 percent cellulose sulfate (CS), also known as Ushercell, is an effective and safe method for preventing HIV transmission. The product has been developed by CONRAD in collaboration with Polydex Pharmaceuticals Ltd.

Two Phase III prevention trials have been planned and will be funded through a pair of $12 million grants: the first from the Bill & Melinda Gates Foundation, and matching funds were committed by the U.S. Agency for International Development (USAID). Such funding is crucial, said CONRAD Director Henry Gabelnick, who also said many companies in the drug industry lack interest for such a venture.

"For it to get done," he told BioWorld Today, "because there doesn't seem to be the likelihood of a large, blockbuster, private sector market for this, it's going to have to be done with foundation and government money."

One trial, implemented by CONRAD, will be conducted in India and four African countries and funded equally by both organizations. The other trial, which began late last year in Nigeria in collaboration with Family Health International, is entirely supported by USAID. Each will enroll about 2,500 people, and last about four years, a duration that includes recruitment, testing, follow-up and analysis.

In the past 10 years, CONRAD has evaluated a number of microbicides and decided to advance Ushercell.

"This one looked to have a broad spectrum of activity," Gabelnick said. "It's also contraceptive."

Previous funding from the Gates Foundation and USAID provided support for earlier-stage studies that demonstrated Ushercell's safety profile. Going forward, the researchers hope the trials will demonstrate a decrease of at least 50 percent in HIV incidence among Ushercell users compared to placebo, and a measurable reduction in incidence of gonorrhea and chlamydia. Efficacy will be measured by the number of people who seroconvert.

Should the studies demonstrate the stated goal's effectiveness in decreasing the incidence of HIV, the research group said the microbicide would lead to overall health care cost savings. Based on mathematical modeling of 73 countries with a gross domestic product of less than $1,200 per year and all sub-Saharan countries, a microbicide of 50 percent efficacy and 20 percent service coverage would prevent 2.5 million new infections and lead to $3.7 billion in direct cost savings to health systems.

Gabelnick said CONRAD plans to eventually submit its data to the FDA and other regulatory bodies for international registration. Polydex, the Toronto biotech firm that owns Ushercell's underlying intellectual property, also is involved in supervising quality assurance in the product's development.

Current HIV prevention methods largely consist of condoms, and Gabelnick also made mention of a study to use tenofovir (Viread, from Gilead Sciences Inc.) as an oral means of blocking HIV transmission. But that trial ran into ethical problems, he said. Activists charged that prostitutes being used for the trial weren't fully informed of the protocol. He added that "condoms are not always a negotiable item" between partners.

Therein lays CONRAD's research into the microbicide field. The research group also is testing Ushercell's contraceptive abilities in an ongoing Phase II trial in the U.S.

A cooperating agency of USAID, CONRAD operates to improve reproductive health by helping to prevent the transmission of HIV/AIDS and other sexually transmitted diseases. It is administered through the Department of Obstetrics and Gynecology at Eastern Virginia Medical School in Norfolk, Va., with its main office in Arlington, Va.