A Randomized Phase III Trial of Endocrine Therapy Plus Entinostat/Placebo in Patients With Hormone Receptor-Positive Advanced Breast Cancer

This randomized phase III trial studies exemestane and entinostat to see how well they work
compared to exemestane alone in treating patients with hormone receptor-positive breast
cancer that has spread to nearby tissue or lymph nodes (locally advanced) or another place in
the body (metastatic). Estrogen can cause the growth of breast cancer cells. Endocrine
therapy using exemestane may fight breast cancer by lowering the amount of estrogen the body
makes. Entinostat may stop the growth of tumor cells by blocking some of the enzymes needed
for cell growth. It is not yet known whether exemestane is more effective with or without
entinostat in treating breast cancer.