The purpose of this study is to evaluate the safety, tolerability and preliminary activity of IEV407 as a single agent and in combination with endocrine therapy (fulvestrant or letrozole) in patients with advanced hormone receptor positive (HR+), human epidermal growth factor receptor 2 negative (HER2-negative) breast cancer.
Age ≥ 18 years old
Patients with inadequate bone marrow and/or organ functions with out-of-range laboratory values.
Impaired cardiac function or clinically significant cardiac disease.
Concurrent use of hormone replacement therapy.
Women of childbearing potential who are unwilling to use highly effective contraception methods, pregnant or nursing women.