Principle from the 1930s: Is the “pill” for men now coming?

At the 2024 BIO International Conference in San Diego, California, the completion of a first Phase 1 study with human subjects using a non-hormonally active substance was announced.

“We are one step closer to creating the first ‘pill’ for birth control for men,” the scientific director of the US biotech company YourChoice Therapeutics was quoted as saying in a press release. Since the advent of hormonal contraception almost 65 years ago, there has not been a similarly large breakthrough in this field. Above all, contraception in this way has remained exclusively a matter for women. The easier accessibility of safe contraception for them is based on the fact that ovulation inhibitors have to inhibit ovulation once a month. However, around 1,000 sperm are produced in the testicles every second.

Subgroup of vitamin A receptors is inhibited

With the support of the US health institutes, the US researchers unearthed a principle in preclinical studies that has been known since the 1930s: At that time, it was discovered that sperm production in mammals stopped if they did not receive vitamin A. The active ingredient YCT-529, which has now been developed by Your Choice Therapeutics, inhibits a subgroup (RAR-a) of vitamin A receptors in the testes. In animal experiments (mice, dogs), it was 99 percent effective in preventing pregnancy. After YCT-529 was discontinued, fertility returned in all male animals.

“No hormones, no problems”

“No hormones, no problems: For now, the first male birth control of its kind is safe,” wrote the biotech news service Fierce about the results presented at the BIO Conference 2024 in San Diego, California last week. 16 subjects had received up to three different doses of the active ingredient. There were no signs of side effects.

The next step is to complete another phase 1 study with test subjects taking multiple doses of YCT-529 by the beginning of 2025, including studies on the metabolism of the active ingredient, etc. The previous contraceptives for men, which are intended for oral use, as regular injections or as a gel, are always intended to work at the level of testosterone levels. Studies on this subject supported by the World Health Organization (WHO) have also been discontinued quite regularly due to side effects.