Overview

• YCT-529 blocks testicular retinoic acid receptors to halt sperm production without altering testosterone levels or libido
• In a randomized, double-blind single-ascending-dose study of 16 vasectomized men, no serious or severe treatment-emergent adverse events occurred up to 180 mg
• One participant experienced a brief asymptomatic arrhythmia at 90 mg and 180 mg but cardiology evaluation showed no structural abnormality
• At 180 mg, drug exposure (AUC0–24 ≈27 300 h·ng/mL) matched levels previously linked to reversible infertility in nonhuman primates
• Ongoing repeat-dose studies over 28 and 90 days are assessing longer-term safety and pharmacokinetics ahead of planned efficacy trials