1:Anticancer Res. 2009 May;29(5):1611-3.Mifepristone may halt progression of extensively metastatic human adenocarcinoma of the colon - case report.
http://www.ncbi.nlm.nih.gov/pubmed/19443374?ordinalpos=1&itool=EntrezSystem2.PEnCheck JH, Dix E, Sansoucie L, Check D.7447 Old York Road, Melrose Park, PA 19027, U.S.A.firstname.lastname@example.org.BACKGROUND: Mifepristone, a progesterone receptor antagonist has been found to improve the length and quality of life in various spontaneous murine cancer models including tumors without progesterone receptors theoretically by inhibiting an immunomodulatory protein that suppresses natural killer cell function in the tumor microenvironment. MATERIALS AND METHODS: Mifepristone 200 mg per day by mouth was given to two patients with stage 4 colon cancer with extensive metastases. RESULTS: Both patients not only survived far longer than expected but had marked improvement in their quality of life similar to mice. Though the metastatic lesions did not disappear, no new ones appeared for a long time and the ones present did not grow. The drug was extremely well tolerated. CONCLUSION: The use of progesterone receptor antagonists may present a novel immunotherapy to help fight cancer. A larger controlled study is needed.1:Clin Exp Obstet Gynecol. 2007;34(4):207-11. Evidence that progesterone receptor antagonists may help in the treatment of a variety of cancers by locally suppressing natural killer cell activity.http://www.ncbi.nlm.nih.gov/pubmed/18225679Check JH,Sansoucie L,Chern J,Amadi N,Srivastava M,Larece KPURPOSE:To propose a novel concept that progesterone receptor antagonists, e.g., mifepristone, may prove effective in treating a variety of cancers--even those not shown to be hormonally dependent or possessing progesterone receptors. METHODS: Multiple human leukemia cell lines were evaluated for mRNA expression of an immunomodulatory protein called the progesterone-induced blocking factor (PIBF) that suppresses natural killer (NK) cell activity during normal pregnancy. Furthermore, we evaluated the effects of progesterone (P) and mifepristone in PIBF protein expression. Finally, the effect of mifepristone treatment of mice with advanced leukemia was evaluated. RESULTS: All tumor cell lines evaluated were found to express mRNA for PIBF and some were found to even express the PIBF protein. The addition of P to the media increased the expression of PIBF and mifepristone downregulated its expression. Treatment of mice with spontaneous leukemia when they already had extensive disease seemed to increase the length and quality of their life. CONCLUSIONS: These data and other experience with mice with lung cancer and some anecdotal human cancer experience suggest that various cancers may utilize similar mechanisms used by the fetus to escape NK cell surveillance. Mifepristone and other progesterone receptor antagonists may deserve a clinical trial in human cancer even where there is no knowledge of the presence of progesterone receptors.