Tucatinib+Trastuzumab+Eribulin in HER2+ MBC

This study is testing a three-drug combination — tucatinib, trastuzumab, and eribulin — for people with HER2-positive metastatic breast cancer who have already received prior treatments including trastuzumab deruxtecan (T-DXd). HER2-positive means the cancer cells carry a protein that fuels their growth, and these drugs target that protein in different ways. **You may be eligible if...** - You have HER2-positive metastatic breast cancer confirmed by biopsy - You have previously received trastuzumab deruxtecan (T-DXd) in the metastatic setting, or your cancer returned after prior HER2-targeted therapy - Your organ function and overall health status are adequate **You may NOT be eligible if...** - You have untreated or actively progressing brain metastases - You have significant heart problems (reduced ejection fraction) - You have had prior treatment with tucatinib or eribulin Talk to your doctor to see if this trial is right for you.