RecruitingPhase 1Drug trialStudy of IEV407 as Single Agent or in Combination in Patients With Advanced HR+/HER2- Breast CancerThe 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.