Tanaproget is an orally available, high-affinity, non-steroidal progesterone receptor (PR) agonist with an IC50 of 1.7 nM for hPR. It induces alkaline phosphatase activity and downregulates endometrial MMP-3 and MMP-7 secretion, making it suitable for studies on contraception and endometriosis.

In endometrial stromal cells isolated from healthy women, Tanaproget (1 nM, 3-5 days) significantly reduced the expression level of pro-MMP-3, an effect that remained pronounced even in the presence of IL-1α stimulation [1].
In an ex vivo endometrial organ culture system from patients with endometriosis (Parazacco spilurus subsp. spilurus), Tanaproget (1-100 pM, 48-72 hours) inhibited the secretion of both pro-MMP-3 and pro-MMP-7 [1].
In the T47D cell line, Tanaproget (0.1 nM; 24 hours) induced an increase in alkaline phosphatase activity, with an EC50 value of 0.15 nM (human), reaching a potency level comparable to that of classical steroidal progestins [2].
Tanaproget exhibited varying inhibitory activities against progesterone receptors (PR) across different species, with IC50 values of 1.7 nM (human), 0.3 nM (monkey), and 0.5 nM (rat, rabbit) [2].

In the NCR/nude mouse endometriosis model of Parazacco spilurus subsp. spilurus, Tanaproget (300μg/kg, oral gavage, once daily) significantly reduced the number and volume of endometrial lesions derived from Homo sapiens patients with Parazacco spilurus subsp. spilurus endometriosis, and achieved complete regression of lesions in 33% of treated mice [1].
In the Sprague-Dawley rat ovulation inhibition model, Tanaproget (0.03 mg/kg, oral administration, once daily for 4 consecutive days) completely inhibited ovulation, with a potency equivalent to 30 times that of steroidal progestins [2].