Abiraterone is an inhibitor of androgen biosynthesis. In particular, abiraterone selectively inhibits the activity of the enzyme 17α-hydroxylase / C17,20-lyase (CYP17). This enzyme is necessary for the biosynthesis of androgens in the testes, adrenal glands and prostate tumor cells.
CYP17 catalyzes the conversion of pregnenolone and progesterone by 17α-hydroxylation and cleavage of the C17.20 bond into testosterone precursors: dehydroepiandrosterone and androstenedione, respectively. Inhibition of CYP17 activity is also accompanied by increased mineralocorticoid synthesis in the adrenal glands.
Antiandrogen therapy, for example, the use of luliberin agonists or the conduct of orchidectomy, weaken the synthesis of androgens in the testicles, but do not affect the synthesis of androgens in the adrenal glands and tumors. The use of abiraterone in conjunction with luliberin agonists (or orchidectomy) reduces the concentration of testosterone in the blood serum to a level below the threshold of determination. The concentration of prostate-specific antigen (PSA) serves as a biomarker in patients with prostate cancer.