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Is Yonsa a form of chemotherapy?

Medically reviewed by Philip Thornton, DipPharm. Last updated on Dec 22, 2022.

Official answer


Yonsa (abiraterone acetate) is a CYP17 inhibitor used in combination with methylprednisolone to treat men with advanced prostate cancer.

Yonsa is not a chemotherapy drug. It is a hormone therapy, which contains the same active ingredient as another prostate cancer treatment called Zytiga.

Yonsa is specifically used to treat prostate cancer that has spread to other parts of the body and no longer responds to other medical and surgical treatments that lower testosterone - metastatic castration-resistant prostate cancer (CRPC).

How does Yonsa work?

After being swallowed, the active ingredient in Yonsa called abiraterone acetate is converted to abiraterone. Abiraterone is an androgen biosynthesis inhibitor, which inhibits the enzyme CYP17 (17 ɑ-hydroxylase/C17, 20-lyase).

CYP17 is involved in the production of dehydroepiandrosterone (DHEA) and androstenedione, which are both androgens and are used to make testosterone.

Androgens are a group of hormones that play a key role in the development and function of the normal prostate gland, but they can also cause prostate cancer to develop and progress.

How does the hormone therapy drug Yonsa differ from a chemotherapy drug?

Yonsa works to prevent prostate cancer cells from growing and spreading by inhibiting the production of androgens, including testosterone. Androgens help prostate cancer cells grow and spread.

Chemotherapy drugs work differently from hormone therapy drugs such as Yonsa. Chemotherapy drugs target cells that are developing and growing, which is a process that does unchecked in cancer cells. Chemotherapy drugs target a specific point in the cell cycle, which is the series of phases the cells go through as they mature. Different chemotherapy drugs have different targets and by interrupting the development of cells as they grow chemotherapy drugs help to slow and stop the growth of cancer cells.


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