Estrogen receptor mutations and functional consequences for breast cancer

Highlights • There is a substantial frequency of ESR1 point mutations in metastatic breast tumors. • ESR1 mutations are implicated in clinical resistance to hormonal therapy. • ESR1 mutations render receptor activity constitutive by altering receptor conformation. • Early detection of the mutations can guide proper selection of therapy. • Novel therapeutics to overcome resistance conferred by the mutations are being tested.