An Open-label, Multi-center, Phase I/Ib Study of IEV407 as a Single Agent and in Combination With Endocrine Therapy in Patients With Advanced Hormone Receptor Positive, HER2- Negative Breast Cancer

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.