Context -Investigational Medicine - Onapristone Extended Release (ONA-XR)
ONA-XR is an investigational medicine that prevents progesterone signaling by blocking the interaction between progesterone and its binding partner, progesterone receptor. Onapristone is the only known full PR antagonist.
Over 75,000 women with metastatic breast, ovarian, or uterine (endometrial) cancers die per year in the United States. For many of these patients, continuous progesterone and estrogen signaling drives disease progression. Currently, only medicines that block estrogen are approved, meaning that progesterone signaling continues in those patients receiving anti-estrogen therapy.
Under normal conditions, progesterone is primarily responsible for the development of sex organs and for regulating the menstrual cycle. Cancer cells hijack progesterone to stimulate cancer cell proliferation, metastases, regeneration, and immune evasion - thus, leading to worse outcomes.