Luteinizing hormone-releasing hormone analogs: their impact on the control of tumorigenesis

The development of the luteinizing hormone-releasing hormone (LH-RH) agonists and antagonists and the principles of their clinical use were reviewed. In the 28 years that have elapsed since the elucidation of the structure of LH-RH, various applications in gynecology, reproductive medicine, and oncology have been established for LH-RH agonists and antagonists. These clinical applications are based on inhibition of the pituitary and the gonads. The advantage of the LH-RH antagonists is due to the fact that they inhibit the secretion of gonadotropins and sex steroids immediately after the first injection and thus achieve rapid therapeutic effects in contrast to the agonists, which require repeated administration. LH-RH antagonists should find applications in the treatment of benign gynecologic disorders and benign prostatic hypertrophy and in assisted reproduction programs. The primary treatment of advanced androgen-dependent prostate cancer is presently based on the use of depot preparations of LH-RH agonists, but antagonists like Cetrorelix already have been tried successfully. Antagonists of LH-RH might be more efficacious than agonists in treatment of patients with breast cancer as well as ovarian and endometrial cancer. Recently, practical cytotoxic analogs of LH-RH that can be targeted to LH-RH receptors on tumors have been synthesized and successfully tested in experimental cancer models. Targeted cytotoxic LH-RH analogs show a great promise for therapy of prostate, breast, and ovarian cancers.