{"entity":{"id":"fluoxymesterone","kind":"drug","name":"Fluoxymesterone","aka":["Androxy"],"tldr":"Fluoxymesterone is an oral male hormone approved in 1956 and once used to palliate advanced breast cancer in women, an approach abandoned when better tolerated antioestrogens and aromatase inhibitors arrived.","summary":"Androgens were among the first hormonal treatments for breast cancer, and fluoxymesterone, a potent oral androgen approved in the United States in 1956, carried a labelled indication for palliation of androgen-responsive recurrent breast cancer in women one to five years past the menopause. Virilisation, liver toxicity and fluid retention limited it, and by the 1980s tamoxifen and then the aromatase inhibitors had replaced androgen therapy. The drug has been discontinued in most markets, but androgen receptor biology in breast cancer is again under study with newer agents such as enobosarm.","status":"historic","asOf":"2026-09-08","wikipedia":"https://en.wikipedia.org/wiki/Fluoxymesterone","links":[{"label":"Wikipedia","url":"https://en.wikipedia.org/wiki/Fluoxymesterone"},{"label":"ChEMBL CHEMBL1445","url":"https://www.ebi.ac.uk/chembl/explore/compound/CHEMBL1445"}],"tags":["gap-fill","chembl-universe"],"related":[],"cancers":["breast-hr-positive"],"sections":[],"technologies":["endocrine-therapy"],"targets":["androgen-receptor"],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"notes":[],"brand":"Halotestin","modality":"Oral small-molecule synthetic androgen","mechanism":"A 17-alpha-alkylated testosterone derivative that activates the androgen receptor; in breast cancer it opposes oestrogen-driven growth and suppresses gonadotrophins.","approvals":[{"region":"US","year":1956,"indication":"Palliation of androgen-responsive advanced breast cancer in postmenopausal women (historic label)"}],"mechanismSteps":[],"toxicity":[],"access":[],"regulatoryEvents":[]},"route":"/drugs/fluoxymesterone/","neighbours":{"cancer":[{"id":"breast-hr-positive","kind":"cancer","name":"HR-positive / HER2-negative breast cancer","route":"/cancers/breast-hr-positive/"}],"technology":[{"id":"endocrine-therapy","kind":"technology","name":"Endocrine therapy (SERMs, AIs, SERDs)","route":"/technologies/endocrine-therapy/"}],"target":[{"id":"androgen-receptor","kind":"target","name":"Androgen receptor","route":"/targets/androgen-receptor/"}]}}