Exemestane (trade name Aromasin) is a medication used to treat breast cancer. It is a member of the class of antiestrogens known as aromatase inhibitors. Some breast cancers require estrogen to grow. Those cancers have estrogen receptors (ERs), and are called ER-positive. They may also be called estrogen-responsive, hormonally-responsive, or hormone-receptor-positive. Aromatase is an enzyme that synthesizes estrogen. Aromatase inhibitors block the synthesis of estrogen. This lowers the estrogen level, and slows the growth of cancers.

Cyclophosphamide (Cytoxan) is a medication that belongs to a group of drugs called alkylating agents. It is used to treat various types of cancer, including lymphoma, leukemia, breast cancer, and ovarian cancer. It works by interfering with the DNA replication process, which inhibits the growth of cancer cells.