D4-Abiraterone is an inhibitor of CYP17A1, 3b-hydroxysteroid dehydrogenase (3βHSD) and steroid 5a-reductase (SRD5A), the main metabolite of abiraterone. D4-Abiraterone is also an antagonist of androgen receptor.

D4-Abiraterone (D4A) (10 mM) almost completely prevented the conversion of D4-androstenedione (AD) to 5α-androstanedione and other 5α-reducing androgens. D4-Abiraterone has greater affinity for androgen receptor (AR) than mutant (expressed in LNCaP, half maximum inhibitory concentration (IC50 = 5.3 nM)) and wild type (expressed in LAPC4, IC50 = 7.9 nM) Abiron (IC50 = 418 and> 500 nM, respectively). Compared with Abi, D4-abiraterone significantly inhibited the expression of PSA, TMPRSS2 and FKBP5 in LNCAP, LAPC4 and C4-2 cell lines. D4-Abiraterone also suppressed AR target gene expression in a dose-dependent manner.

In preventing the conversion of 3β-hydroxysteroid dehydrogenase (3βHSD) from dehydroepiandrosterone (DHEA) to D4-androstenedione (AD) in LNCaP and VCaP xenografts, D4-Abiraterone (D4A) The effect is ten times higher than that of Abiron. In LNCaP and VCaP xenografts, AD accumulation was blocked at 48 h, and 0.1 μMD4-Abiraterone was equivalent to 1 μMAbi. Compared with the Abirate acetate group, the progress of the D4-Abiraterone group was significantly delayed (P = 0.011). Compared with abirate acetate, D4-Abiraterone treatment can increase progression-free survival .