BOSTON — An investigational male contraceptive gel suppresses sperm more rapidly than previous products in development, new data suggested.
The product 8 mg segesterone acetate (Nestorone) combined with 74 mg testosterone (“NesT”) is a gel that a man applies daily to both shoulders. The progesterone blocks spermatogenesis, and the testosterone restores blood levels to maintain sexual function. It is under development by the National Institute of Child Health and Human Development (NICHD) in collaboration with the Population Council, the Los Angeles Biomedical Research Institute, and the University of Washington School of Medicine.
Currently, the only available male contraceptives are vasectomy, which isn’t easily reversible, and condoms, which have a high failure rate. Previous attempts to develop a “male pill” have been unsuccessful for a variety of reasons, but so far, this product appears effective and safe, Diana Blithe, PhD, chief of the Contraceptive Development Program at NICHD, said at a press briefing held on June 2, 2024, during ENDO 2024: The Endocrine Society Annual Meeting.
“It’s been a long time coming…Men need and want more contraceptive options such as an effective reversible method,” she told Medscape Medical News.
New phase 2b data show that among 222 couples in which the man initially had normal (> 15 million/mL) sperm counts, the median time to suppression (
After two consecutive counts of
Asked to comment, session moderator Frances Hayes, MBBCh, associate clinical chief of the Division of Reproductive Endocrinology at Massachusetts General Hospital, Boston, said, “certainly, I think it’s a big advance on what we have so far…I think it’s showing great promise.”
Hayes did caution, though, that “with real-world use, daily application of a gel might be a bit more challenging than taking an injection…an injection is more consistent. With a gel, patients might forget or shower it off. But I don’t think 1 day of interruption would be a significant thing.”
Transference of the topical to a partner or a child is another potential concern, Hayes noted, although this is true of current testosterone gel products as well. During the briefing, Blithe said that this issue is why the product is recommended to be placed on the upper arms rather than the abdomen or another spot more likely to come into contact with another person. Also, in the trial, men were instructed to wear shirts during intercourse.
Regarding the rapidity of sperm suppression, Hayes said, “It’s surprising. It looks great as a reversible contraceptive…Normally, you think of the life cycle of the sperm being about 72 days. So to see 50% suppression by 8 weeks, and then 85%-90% by 15 weeks, that’s very rapid. It may be that the progesterone that they’re using is very potent. Progestins can have some negative effects on lipids on mood. We didn’t really see the safety data in this presentation. So that will be interesting to see.”
During the briefing, Blithe said that the phase 2b trial is expected to finish by the end of this year, and in the meantime, the researchers are communicating with the US Food and Drug Administration about the design of a phase 3 trial because this is an unprecedented area. “They don’t have guidelines yet. They’ll need to develop them first.”
Blithe has been the NICHD principal investigator on cooperative research and development agreements with HRA Pharma and Daré Bioscience. Hayes had no disclosures.
Miriam E. Tucker is a freelance journalist based in the Washington, DC, area. She is a regular contributor to Medscape Medical News, with other work appearing in the Washington Post, NPR’s Shots blog, and Diatribe. She is on X: @MiriamETucker.
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