Clinical Trial

Retrospective Observational Study of Hormone Receptor Positive (HR+) and HER2-low (IHC1+ or 2+ with ISH negative) and HER2- ultralow (IHC0 with membrane staining) Metastatic Breast Cancer (MBC)

Brief Summary: This is a multicenter retrospective observational study in participants with HR+ HER2-low and HER2-ultralow MBC. ENHERTU treatment should have been received on or after September 2022 and other treatments could have been received prior to September 2022

Key Eligibility Criteria:

• HR+ HER2-low and HER2-ultralow MBC participants who have received at least 2 cycles of treatment with ENHERTU
• HR+ HER2 negative defined as IHC0 without membrane staining excluded
• HR+ HER2-positive excluded
• HR- HER2-positive, HER2-low, HER2-ultralow and negative excluded