Some cases of metastatic breast cancer have mutations in the gene encoding the estrogen receptor, according to two independent studies published online this week in Nature Genetics. These findings suggest that estrogen receptor antagonists may have therapeutic effects against some cases of metastatic breast cancer.
Sarat Chandarlapaty and colleagues sequenced 230 genes in 36 metastatic breast cancers resistant to hormonal therapy and identified mutations in the ESR1 gene in nine of the tumors. They then analyzed ESR1 in 44 metastatic breast cancers and identified mutations in five of the tumors.
In a second study, Arul Chinnaiyan and colleagues sequenced the exomes of 11 metastatic breast cancers and identified mutations in the ESR1 gene in six of the tumors. Both groups used cultured cells to show that the mutant estrogen receptors were active in the absence of estrogen hormone and that the mutant estrogen receptors were responsive to anti-estrogen therapies.