A Study to Assess the Efficacy and Safety of Enzalutamide With Trastuzumab in Patients With Human Epidermal Growth Factor Receptor 2 Positive (HER2+), Androgen Receptor Positive (AR+) Metastatic or Locally Advanced Breast Cancer

Inclusion Criteria

• •The subject has histologically or cytologically proven adenocarcinoma of the breast that is HER2+
• •The subject has AR+ breast cancer
• •The subject has metastatic disease or has locally advanced disease that is not amendable to curative treatment
• •The subject has measurable disease or nonmeasurable, evaluable disease per RECIST 1.1. (NOTE: pleural effusions, ascites or other third fluid space are not evaluable diseases per RECIST 1.1).
• •The subject has received at least 1 line of therapy in the metastatic or locally advanced disease setting. The subject has been documented to have progressed by determination of the investigator on a regimen containing an anti-HER2 agent as the most recent regimen or the most recent anti-HER2 regimen was discontinued for any toxicity, with the exception of a cardiotoxicity.
• •The subject has adequately recovered from toxicities due to prior therapy.
• •The subject has an Eastern Cooperative Oncology Group performance (ECOG) status ≤ 1 at Screening and Day 1
• •The subject has available at the site a representative, formalin-fixed, paraffin-embedded, tumor specimen that enabled the definitive diagnosis of breast cancer with adequate viable tumor cells in a tissue block (preferred) or ≥ 10 (20 preferred) freshly cut, unstained, serial slides and the associated pathology report
• •The subject has a history of seizure or any condition that may predispose to seizure (e.g., prior cortical stroke, significant brain trauma).
• •The subject has a history of loss of consciousness, cerebrovascular accident, or transient ischemic attack within 12 months before the Day 1 visit.
• •The subject has had a hypoglycemic episode requiring medical intervention while on insulin (or other anti-diabetic) treatment within 12 months before Day 1.
• •The subject had a major surgical procedure, substantial open biopsy, or significant traumatic experience within 28 days before the Day 1 visit, or anticipation of need for major surgical procedure during the course of the study.
• •The subject has had palliative radiation therapy to bone metastases within 14 days prior to the Day 1 visit (side effects from radiation must be resolved).
• •The subject has received chemotherapy, immunotherapy, or any other systemic anticancer therapy, with the exception of anti-HER2 therapy (e.g., trastuzumab), within 14 days prior to the Day 1 visit.