What is the mechanism of action of CYP17 inhibitors?

CYP17 inhibitors function by inhibiting the enzyme CYP17, which is crucial for the biosynthesis of androgens such as testosterone and dehydroepiandrosterone (DHEA). This enzyme plays a pivotal role in the production pathway of these hormones, which are implicated in conditions like prostate cancer. By blocking CYP17, these inhibitors effectively decrease the levels of circulating androgens, thereby reducing androgen receptor activation, which is necessary for the growth and survival of androgen-dependent tumors.

This targeted approach is significant because it disrupts the hormonal support that some cancers rely on, leading to a reduction in tumor growth. The other options do not accurately describe the action of CYP17 inhibitors, as they do not prevent androgen binding, block estrogen receptors, or enhance androgen production. Instead, they specifically inhibit the synthesis of androgens at the enzymatic level, making option B the correct choice.