Key Findings
- Marked organ- and histology-specific molecular and immune heterogeneity was observed across 2,645 metastatic breast cancer biopsies, supporting site-aware interpretation of metastatic biopsies and biomarker assessment in advanced disease.
- This study demonstrates how integrated genomic, transcriptomic, and immune profiling can identify biologically distinct breast cancer subgroups, refine therapeutic stratification, and uncover potential biomarkers of treatment response and resistance across metastatic, hormone receptor–positive, and triple-negative disease.