Estrogen receptor (ER) is present in 85% of all breast cancers, and more than 90% of ER+ positive breast cancers also contain the AR which has been demonstrated to be an important therapeutic target in ER+ breast cancer. Enobosarm is an oral drug that selectively targets the AR in breast cancer without having the unwanted virilizing androgen adverse side effects including facial hair, acne, increase in hematocrit, or liver toxicity, while having potential clinical benefits including increasing muscle and physical function as well addressing cancer treatment induced bone loss and fractures. Enobosarm has extensive nonclinical and clinical experience having been evaluated in 25 separate clinical studies with 2,091 enrolled patients, including three Phase 2 clinical studies in advanced breast cancer. There are also at least two enobosarm investigator-initiated Phase 2 clinical studies in advanced breast cancer.