ICI 182,780 is a high affinity pure estrogen receptor antagonist, which is devoid of any partial agonism, and is also a high affinity agonist at the G protein-coupled estrogen receptor 1 (GPER), also known GPR30. ICI 182,780 inhibits MCF-7 human breast cancer cell growth in vitro and shows antitumour activity in mouse models. ICI 182,780 is a highly selective estrogen receptor downregulator, which is able to bind, block, and accelerate estrogen receptor (ER) degradation through inhibition of ER transcriptional activity. ICI 182,780 is a clinically useful option for some advanced breast cancers.
