Drug Repurposing for Cancer Therapy.

In the mid-1980s, a French company geared its efforts toward developing a synthetic steroid capable of blocking the glucocorticoid receptor in order to potentially treat Cushing’s syndrome. Preclinical studies revealed that the compound developed, termed RU-38486, was indeed a potent antiglucocorticoid agent [1], yet with a caveat: if given to pregnant animals, it terminated pregnancy [2-4]. Thus, a compound originally developed for treating one disease, rapidly acquired a different identity, was named mifepristone and investigated in depth for its abortifacient properties through the blockage of uterine progesterone receptors [4,5]. In other words, developed with one intended use, RU-38486 was repurposed for another modality of use even before gaining approval for medical usage. In the US, the Food and Drug Administration (FDA) approved mifepristone for chemical termination of early pregnancy in September 2000 [6]. It took 12 more years for the FDA to support mifepristone for its intended original use, the treatment of Cushing’s disease. In February 2012, the FDA approved mifepristone to control hyperglycemia in adults with endogenous Cushing’s syndrome and not eligible for surgery [7].