Hormone-Based Cancer Drugs

Hormone is responsible for the growth of certain cancers. Hormone-sensitive cancers can be treated with drugs that prevent hormone production or block the action of the hormone, thus prevent tumor growth.

Table 15. Hormone-Based Cancer Drugs

Two classes of drugs most commonly used as hormonal therapy in breast and prostate cancers include: 1. Luteinizing hormone-releasing hormone (LHRH) analogs. This class of drugs, including D63153, Teverelix, and Zoladex, prevents hormone production. 2. Antiandrogens or antiestrogens. This class of drugs, including Casodex, Faslodex, and Tamoxifen, blocks the actions of hormones. The antiestrogen Tamoxifen is used to prevent estrogen stimulation of breast cancer cells. Tamoxifen binds to the estrogen receptor but the complex is not productive, that is, the complex fails to induce estrogen-responsive genes and RNA synthesis does not ensue. The result is a depletion of estrogen receptors, and the growth-promoting effects of the natural hormone and other growth factors are suppressed.

Arimidex and Femara are aromatase inhibitors and highly potent estrogen suppressor. It acts by interfering with the production of estrogen triggered by aromatase and reduces the total amount of estrogen in the body. As a result, less estrogen can reach breast cancer cells.Hormone-dependent breast cancers contain protein molecules called estrogen receptors. When no estrogen is present, the estrogen receptors remain inactive. When the estrogen receptors are exposed to estrogen, however, they trigger a chain of events that results in tumor cell growth and multiplication. Aromatase enzyme is needed to convert androgen into estrogen, which results in tumor growth. The drugs bind to the aromatase enzyme and block it from converting androgen to estrogen, thereby reducing growth of the tumor. Tumors that contain these estrogen receptors are known as estrogen receptor-positive (ER+) tumors. These are the cancers that can be treated by drugs to deprive them of estrogen. Acapodene is a selective estrogen receptor modulator (SERM).

D17DT (anti-gastrin 17) is a vaccine, containing a portion of the hormone gastrin 17 (G17), and diphtheria toxoid (DT), chemically bound together to form G17DT, neutralizes both G17 and the hormone Gly-G17 to treat relevant cancers. Phase III results showed that the drug had no overall survival benefit in pancreatic cancer compared to placebo and development for pancreatic patient was terminated in May 2005.

GnRH Pharmaccine is a vaccine that neutralizes the GnRH hormone for hormone-failed or hormone-resistant patients with prostate cancer.