Breast cancer has been treated successfully with selective estrogen receptor antagonists (SERMs) such as tamoxifen, receptordepleting agents such as fulvestrant, and aromatase inhibitors such as anastrozole. Selective progesterone receptor modulators (SPRMs or PRMs) have not been studied as much and are currently under investigation for inhibition of mammary carcinogenesis in animal models and breast cancer prevention trials in women. | Turkish Journal of Biology Review Article Turk J Biol (2014) 38: 772-785 © TÜBİTAK doi: Progesterone receptor modulators in breast cancer , Ronald D. WIEHLE* ** Repros Therapeutics, The Woodlands, Texas, USA Received: Accepted: Published Online: Printed: Abstract: Breast cancer has been treated successfully with selective estrogen receptor antagonists (SERMs) such as tamoxifen, receptordepleting agents such as fulvestrant, and aromatase inhibitors such as anastrozole. Selective progesterone receptor modulators (SPRMs or PRMs) have not been studied as much and are currently under investigation for inhibition of mammary carcinogenesis in animal models and breast cancer prevention trials in women. They might follow tamoxifen and aromatase inhibitors in the adjuvant treatment of breast cancers with acquired resistance. These uses have not provoked ground-breaking progress or studies and PRMs do not have a high profile. Most in vitro and in vivo studies indicate that PRMs preferentially suppress cell proliferation and also induce apoptosis. In this review we summarized the data on the effects of PRMs and particularly of the antiprogestins RU-486 (mifepristone) and CDB-4124 (Progenta, Proellex or telapristone acetate) on breast cancer models. Both agents have been employed in preclinical and clinical studies for prevention and treatment of breast cancer. This author believes that PRMs should be investigated more intensely. Key words: Progesterone receptor, PRMs, antiprogestins, mammary carcinogenesis, biomarkers 1. The case for progesterone receptor modulators (PRMs) for breast cancer PRMs have shown benefit in women with uterine leiomyomas and endometriosis and those successes in clinical trials have led to the realization that the antiproliferative and pro-apoptotic actions seen may find use in other progesterone-sensitive tissues. As a prime developer of a .
