Researchers are studying a novel contraceptive delivery system, which uses a vaginal film to produce antibodies to sperm. The same film also could be developed to protect against HIV infection and herpes (HSV).1,2
“It’s been known for some time that a large percentage of infertile patients have anti-sperm antibodies. They’re associated with reduced sperm function, which is speculated to cause infertility,” says Deborah J. Anderson, PhD, professor of medicine, OB/GYN, and microbiology at Boston University School of Medicine.
Studies have detected anti-sperm antibodies in approximately 15% of couples with unexplained infertility.1
“We have been interested in anti-sperm antibodies for contraception,” Anderson says. “Because the monoclonal antibodies are so much better [evolved] now, we were finally able to produce a medical-grade monoclonal antibody for contraception.”
The antibody was first developed in the 1980s in Japan from the blood of an infertile woman. Investigators sequenced it and put the gene sequence in a new antibody platform, which uses tobacco plants.
“We put the antibody’s DNA in the tobacco plant, and the plants produce clean reagent-grade antibodies,” she adds.
In a Phase I clinical trial, which began in early 2021, investigators recruited couples and gave women the contraceptive film containing the antibody. The woman inserts the film into her vagina and the couple have intercourse about an hour after insertion.
“Then they come into the doctor’s office within two hours and the woman’s cervical mucus is sampled, and the number of progressive sperm in the cervical mucus is tested,” Anderson explains. “It is a pretty good indicator of whether the sperm are impaired by the contraceptive.”
The film is rectangular and about an inch wide. Survey results suggest it is easy to use, Anderson says. “We are hopeful this will be a good method,” she adds. “We could put the antibody in a gel, tablet, or ring, but this is what we’re testing right now.”
Earlier, Anderson and colleagues completed a Phase I clinical trial using a similar film, called MB66, to prevent HIV and HSV infections. The investigators found that single and repeated intravaginal applications of the film were well-tolerated, safe, and acceptable to study participants.2
Concentrations of the anti-HIV/HSV agents were significantly elevated, suggesting that they could provide protection for up to 24 hours post-dose. The same platform also could protect against other sexually transmitted infections as well as provide contraception.
The early research shows that the film dissolves within an hour of placement in the vagina, and the women’s sexual partners could not discern its presence. Also, there were no reported side effects, Anderson says.
Studies of the contraceptive film took place in the United States. If the film is successful in future clinical trials, it could be used worldwide.
“There are a lot of couples who will have sex infrequently and don’t really want to use a method like the pill that is constant; they want to use a contraceptive when they need it,” Anderson explains. “We call this an on-demand method.”
On-demand contraception is appealing to a large percentage of women who are not interested in taking birth control pills or using an intrauterine device, she says. Compared to a spermicide like N9 that is used in gels and foams, the new contraceptive film product is not messy, does not cause irritation, and can last longer.
“A film may be more discreet and acceptable to a lot of women,” Anderson says.
Plus, a woman-controlled product that can provide protection against sexually transmitted infections and work as a contraceptive could be very popular should it become available to consumers.
“We think it’s going to be a game-changer, especially for preventing HIV and herpes,” Anderson says.
- Baldeon-Vaca G, Marathe JG, Politch JA, et al. Production and characterization of a human antisperm monoclonal antibody against CD52g for topical contraception in women. EBioMedicine 2021;69:103478.
- Politch JA, Cu-Uvin S, Moench TR, et al. Safety, acceptability, and pharmacokinetics of a monoclonal antibody-based vaginal multipurpose prevention film (MB66): A Phase I randomized trial. PLoS Med 2021;18:e1003495.