Targeting the Progesterone Receptor in Breast Cancer: Mind the Short Form!

The presurgical window of opportunity trial (WOT) MIPRA provides evidence that neoadjuvant treatment with the prog-esterone receptor (PR) antagonist mifepristone (RU486) may benefit patients with estrogen receptor-positive (ER+) breast cancer characterized by a high ratio of PR-A versus PR-B iso-form (>1.5), suggesting that PR may be targeted in a subset of patients. See related article by Elia et al., p. 866