Progress in Nonhormonal Male Contraception Advances in Early Clinical Studies
Early clinical studies highlighted nonhormonal male contraception candidates YCT-529 and ADAM. YCT-529 showed favorable phase 1a safety, while ADAM reported mild transient effects and durability up to 24 months.
Male contraceptives represent a step toward equality in reproductive responsibility. Nonhormonal pharmacologic male contraceptives look to bypass the challenges of hormonal approaches, acting on testis-specific pathways, sperm function without endocrine disruption, and generation of sperm.
Condoms and vasectomy are still the only methods of male contraception available, and both have drawbacks due to their complex process of reversibility or poor reliability. Hormonal approaches have shown efficacy but are hindered by systemic adverse effects such as weight gain, mood changes, and decreased libido. The integration of male contraceptives, particularly nonhormonal pharmacologic approaches, allows for an opportunity to offset this responsibility, decrease the health risk placed upon women, and give individuals more flexible options for child planning.
YCT-529, a selective retinoic acid receptor α (RAR-α) antagonist, disrupts spermatogenesis without altering systemic testosterone. A phase 1a trial enrolled 16 vasectomized men who received single ascending doses of 10 mg, 30 mg, 90 mg, or 180 mg of YCT-529 in the fasted state, with an additional 30-mg dose in the fed state to assess food effects. Single doses up to 180 mg were safe and well tolerated with no effects on heart rate, hormone levels, sex hormone-binding globulin, inflammatory biomarkers, sexual desire, or mood. There was no clear food effect on pharmacokinetics. Larger phase 1b/2 studies are ongoing to evaluate multiple-dose safety, tolerability, pharmacokinetics and pharmacodynamics, and sexual function and mood in healthy males.
ADAM is an injectable hydrogel that occludes the vas deferens to block sperm transport while maintaining ejaculation and sensation. A first-in-human dose-ranging trial enrolled 25 men seeking long-acting contraception as an alternative to vasectomy. The study showed mild adverse effects with preliminary azoospermia at 90 days; temporary scrotal enlargement and mild scrotal/inguinal pain were the most common adverse effects, resolving within 1 month without activity impairment. Durability up to 24 months was reported at the American Urological Association 2025 Annual Meeting. It is estimated that the contraceptive can last up to 2 years, potentially providing prolonged reproductive control.