Aromatase inhibitors are drugs used in postmenopausal women to treat breast cancers that are fueled by estrogen. They interfere with the production of estrogen in the body. However, in some women, the breast cancer stops responding to these drugs. Exemestane is an example of an aromatase inhibitor.
In this study, researchers want to find the highest dose of an investigational drug called LEE011 that can be given safely with exemestane and with another drug, everolimus, in postmenopausal women with locally advanced or metastatic estrogen receptor-positive, HER2-negative breast cancers that continue to grow despite aromatase inhibitor therapy.
Everolimus is a drug used in combination with exemestane. It works by blocking the activity of a molecule called mTOR, which helps cancer cells grow. LEE011 blocks a protein called CDK, which tells cancer cells to divide. Researchers hope LEE011 will slow the growth of cancer cells and lead to their death.
Patients in this study will receive LEE011 with exemestane and everolimus, or LEE011 with exemestane alone. All three drugs are taken orally (by mouth).