The Population Council is developing an antiretroviral (ARV)-based gel to prevent the transmission of HIV, HSV-2, and HPV in women and men.
Worldwide, an estimated 1.8 million people are infected with HIV annually, and more than a million people contract STIs every day. HSV is an often-painful chronic viral STI that can increase an individual’s susceptibility to other infections, including HIV, while HPV increases the risk of HIV acquisition and is the principal global cause of cervical cancer.
Developing a safe and effective microbicide for vaginal and/or rectal use is considered to be a key step in reducing the global epidemics of HIV and STIs. Researchers are particularly interested in developing multipurpose prevention technologies or MPTs, single products that can address multiple sexual and reproductive health needs. Microbicides that can be used around the time of sex also have the potential to improve prevention product use, or adherence. Although the majority of microbicide research has focused on products to prevent HIV infection associated with vaginal sex, important strides are being made in research aimed at addressing the need for rectal microbicides.
The Population Council has developed and is testing a new microbicide gel called PC-1005 to prevent three non-curable viral STIs simultaneously. It is the first multipurpose gel for both vaginal and rectal use. The gel, which is also known as MZC, contains:
- MIV-150 (M), an enzyme inhibitor that prevents HIV-infected cells from producing new virus;
- zinc acetate (Z), an antiviral agent with activity against HIV and HSV;
- and carrageenan (C), a seaweed-derived compound that is among the most potent anti-HPV agents discovered to date.
The compounds in the gel enhance each other’s effectiveness – providing increased antiretroviral activity at lower doses, which has the potential to increase the safety and reduce the cost of the product.
Council researchers and our collaborators have tested the gel in in vitro (in cells and tissues), in vivo (in animals) and in human studies. These studies have shown that PC-1005 completely blocked vaginal simian immunodeficiency virus (SHIV-RT) infection in monkeys for up to 8 hours after gel application and reduced rectal SHIV-RT infection when applied 1 hour prior to challenge. The gel also effectively blocked vaginal and rectal HSV-2 and HPV infection in mice and vaginal HSV-2 infection in macaques.
In its first human trial, PC-1005 was well tolerated when used vaginally, with no increase in adverse events over placebo. Cervicovaginal lavages from women who used the gel vaginally demonstrated activity against HIV and HPV, with no increase in adverse events over placebo. Acceptability of the gel was high, with 94% of participants reporting willingness to use it in the future.
Based on these results, a further Phase I study, MTN-037, will measure the safety and acceptability of the gel, and the presence of the drug in the blood and tissue, of women and men using the product rectally. The new study is being conducted by the Microbicide Trials Network at the University of Pittsburgh Medical Center and the University of Alabama at Birmingham, with funding from the U.S. National Institutes of Health. Results are expected in mid-2019.
The Population Council brings decades of experience to the development of new products and strategies to protect women and men’s sexual and reproductive health. Scientists at the Council’s Center for Biomedical Research (CBR) are advancing knowledge of the biological mechanisms of HIV transmission, pathogenesis and disease progression and developing new user-controlled MPTs that will allow man and women to prevent HIV, other STIs and in some cases, unintended pregnancy. If proven safe and effective, next-generation microbicides such as PC-1005 could help millions of women and men to protect themselves from HIV and other STIs.