1.Randomized phase II study of lonaprisan as second-line therapy for progesterone receptor-positive breast cancer.
Jonat W1, Bachelot T, Ruhstaller T, Kuss I, Reimann U, Robertson JF. Ann Oncol. 2013 Oct;24(10):2543-8. doi: 10.1093/annonc/mdt216. Epub 2013 Jun 20.
BACKGROUND: The progesterone-receptor (PR) antagonists onapristone (type I) and mifepristone (type II) showed modest activity in hormone-receptor-positive breast cancer; however, onapristone in particular was associated with hepatotoxicity. Lonaprisan is a novel, type III PR antagonist that was well tolerated in phase I studies.
2.The antiprogestin Lonaprisan inhibits breast cancer cell proliferation by inducing p21 expression.
Busia L1, Faus H, Hoffmann J, Haendler B. Mol Cell Endocrinol. 2011 Feb 10;333(1):37-46. doi: 10.1016/j.mce.2010.11.034. Epub 2010 Dec 5.
The ovarian steroid hormone progesterone is essential for normal mammary gland physiology but may also play a role in breast cancer. Highly potent and selective antiprogestins may therefore represent a new treatment option for this disease. Here we studied the effects of the new antiprogestin Lonaprisan on the T47D breast cancer cell line. Strong inhibition of cell proliferation and arrest in the G0/G1 phase were observed, as well as induction of a senescence-like phenotype. This was accompanied by p21 induction through direct binding of Lonaprisan-bound progesterone receptor (PR) to the promoter. Reduction of p21 levels blunted the antiproliferative effects of Lonaprisan. Mutation analysis showed that intact PR DNA-binding properties were needed for p21 induction. Phosphorylation of PR Ser345 was stimulated by Lonaprisan, but this post-translational modification was not required for p21 promoter activation, nor was the interaction with c-Src needed.