Development of p-carborane-based nonsteroidal progesterone receptor antagonists

Progesterone receptor (PR) regulates various physiological processes, including the female reproductive system, and development of nonsteroidal PR antagonists is considered desirable for clinical application, as they are expected to have reduced side effects. We have synthesized a series of nonsteroidal PR antagonists using a 4-cyanophenyl-p-carborane core structure. Among them, compound 14d exhibited potent PR-antagonistic activity (IC50: 27 nM). It showed high binding affinity for PR, but did not bind to androgen receptor or estrogen receptor. This PR-selective antagonist may be a promising lead compound for clinically applicable progesterone receptor modulators.