A birth control pill for men is progressing through the clinic after clearing a safety hurdle in its first human trial. The drug, which its developer YourChoice Therapeutics claims is the only non-hormonal male birth control pill in human studies, is in the midst of a second trial, putting it in contention to become the first oral contraceptive for men. But the potential to shift responsibility in pregnancy prevention has stirred up emotions even in scientific circles, said Nadja Mannowetz, the company’s chief scientific officer.
“I always thought when working with regulatory agencies, we would talk about science and safety findings,” she said, pointing out that many of the questions they’ve gotten seem to carry a different undertone. “You want to decrease sperm counts in men — what if something goes wrong? Would they ask that same question if we were to introduce that as a female contraceptive? I doubt that.”
Still, Mannowetz welcomes the public perception challenge as part of the innovation process. If the pill, dubbed YCT-529, succeeds, it could revolutionize a field that has seen little progress since the FDA approved the female birth control pill more than 60 years ago.
The lag in male contraception
While women’s options have largely stagnated since the 1960s, men still rely on 19th-century technologies — condoms and vasectomies — despite decades of research into alternatives. One option, a hormonal injection, was shelved due to side effects such as mood swings and acne, which are also common in female hormonal contraceptives. But because men don’t face physical risks related to pregnancy and childbirth, the bar for the benefit-to-risk ratio is higher.
“It is true that men, if you just speak in traditional terms, will never get pregnant,” Mannowetz said. But that doesn’t mean they don’t face consequences from unintended pregnancies, she pointed out.
Giving men the ability to control their fertility also benefits women, particularly those who can’t or don’t want to use available options. And men seem willing. According to one poll from 2024, 61% of men said they would try a new contraceptive.
YCT-529 is part of a rising wave of options in development, including ADAM, a reversible sperm-blocking hydrogel from Contraline; EP055, a non-hormonal pill from Eppin Pharma that reduces sperm motility; and a wearable contraceptive device from Entrelac.coop.
The hormone-free approach
Early phase 1a trial results showed YCT-529 was safe and well tolerated, allowing it to advance into a larger 1b/2a study that will focus on safety, tolerability and efficacy by monitoring sperm counts, Mannowetz said. In animals, the drug was 99% effective and 100% reversible with no side effects.
The medication, taken daily or potentially less frequently, may not kick in for weeks at first and could last in the system for up to 85 days before fertility is restored, Mannowetz said. The pill halts sperm production in the testes by blocking an essential retinoic acid receptor. And this mechanism is part of a natural process, Mannowetz said.
“This [retinoic acid] receptor is also present in other tissues of the body. But in adults, it doesn't play a major role anymore,” she said. “And so far, if we just look at our animal studies, and also at our completed clinical trial, we haven't seen any negative side effects, which just points to this receptor being predominantly important in the testes.”
Researchers will learn more as studies progress, but some experts were initially skeptical that the mechanism would be free of side effects.
If YCT-529 pans out, the pill promises a sorely needed option.
“We are living in a world where women's reproductive rights are becoming narrower,” Mannowetz said. “A male product will be a win-win situation. It will help women offset the contraceptive burden, and at the same time, it will give men, especially all the men who want to take on responsibility when it comes to contraception, the possibility to do that.”
