Phase 1, First-in-Human Study of RAD140 in Postmenopausal Women With Breast Cancer

Key Inclusion Criteria: * Progressive metastatic or locally advanced or metastatic breast cancer. * Clinically confirmed as postmenopausal. * Eastern Cooperative Oncology Group (ECOG) score of 0 to 1 at screening. Key Exclusion Criteria: * HER2 positive patients by local laboratory testing. * Triple negative breast cancer. * Any chemotherapy within the 28 days prior to the first dose of study drug. * Any non-chemotherapy anti-cancer drug less than 5 half-lives (30 days for biologics) or less than 14 days for small molecule therapeutics, or if half-life is not known. * Tamoxifen and aromatase inhibitors within 14 days prior to the first dose of study drug. * Fulvestrant within 30 days prior to first dose of study drug. * Any investigational drug therapy within 5 half-lives of the previous investigational study drug or 30 days, whichever is shorter. * Radiation therapy for breast cancer within 2 weeks of dosing and planning to have radiation therapy during participation in this study. * Known history of human immunodeficiency virus infection (HIV) or hepatitis C or active hepatitis B infection, unless the patient was diagnosed \>10 years prior to enrollment and no evidence of active liver disease. * Currently taking testosterone, methyltestosterone, oxandrolone (Oxandrin), oxymetholone, danazol, fluoxymesterone (Halotestin), or testosterone-like agents. * Untreated or uncontrolled brain metastasis. * Diagnosed with or treated for cancer within the previous 2 years, other than breast cancer or non-melanoma carcinoma of the skin. * Pregnant and nursing females.