Simple explanation
Some prostate cancers depend on androgen signaling for growth. Androgens include testosterone and related hormones.
Abiraterone reduces androgen production by blocking CYP17A1, an enzyme required for steroid hormone and androgen synthesis.
Detailed mechanism
Abiraterone acetate is converted to the active compound abiraterone. Abiraterone inhibits the steroidogenic enzyme complex CYP17A1, which has 17-alpha-hydroxylase and C17,20-lyase activity. This interferes with steroid intermediates needed for androgen production.
CYP17A1 is present in tissues involved in androgen production, including the testes, adrenal glands and prostate tumor tissue. Consequently, CYP17 inhibition can reduce androgen availability from several sources.
Why mineralocorticoid effects occur
CYP17 inhibition also changes steroid production upstream of cortisol. The resulting hormonal shift can increase mineralocorticoid activity and contribute to:
- Hypertension
- Hypokalemia
- Fluid retention
- Edema
These effects help explain why corticosteroid therapy and monitoring are important during treatment.
Abiraterone is not a conventional androgen-receptor blocker
Abiraterone works primarily by reducing androgen synthesis rather than directly blocking the androgen receptor. It therefore belongs to the androgen-biosynthesis-inhibitor group.