Drs. John and Benita Katzenellenbogen have developed a novel class of anti-estrogen compounds with the potential to act as breast cancer therapeutics. These compounds show potent anti proliferation effects and downregulation of estrogen receptor α. Importantly, these compounds have enhanced bioavailability compared with currently prescribed therapeutics and due to their potency can be administered at lower doses, which minimizes deleterious side effects. Intriguingly, these compounds also show strong binding to various ERα mutants which are common in breast cancer patients.