You will be shown a question, followed by excerpts from biomedical research papers. Please answer the question based on the provided context. Do not include any text in your response other than the answer.

Question: What is the mechanism of action of abiraterone?

Context: The recognition of sustained androgen dependence of CRPC has led to the identification of more potent and selective inhibitors of androgen synthesis and androgen-receptor signaling, such as abiraterone and enzalutamide, respectively.
This review summarizes the rationale, mechanism of action and relevant clinical data of abiraterone acetate , an oral androgen biosynthesis inhibitor, in the management of CRPC.
Sipuleucel-T, an immunotherapeutic vaccine, is now available in the US for patients with non-metastatic CRPC and abiraterone, an oral enzyme inhibitor of androgen biosynthesis, as well as cabazitaxel, a cytotoxic chemotherapeutic, have been approved for the treatment of metastatic CRPC.
Abiraterone (17-(3-pyridyl)androsta-5,16-dien-3beta-ol, 1) is a potent inhibitor (IC50 4 nM for hydroxylase) of human cytochrome P45017alpha.
Abiraterone acts by inhibiting cytochrome P450 17α-hydroxylase (CYP17A1), a critical step in androgen biosynthesis, thus leading to inhibition of androgen biosynthesis.