Patient Derived Organoid-guided Personalized Treatment Versus Treatment of Physician's Choice in Breast Cancer

This study is testing whether using a lab-grown mini-tumor (called a patient-derived organoid) created from the patient's own cancer cells to predict which drug will work best — can lead to better treatment outcomes in patients with advanced breast cancer that has stopped responding to standard therapies. **You may be eligible if...** - You are 18 or older - You have locally advanced or metastatic breast cancer confirmed by biopsy - You have already been through at least 2 prior treatment regimens and your cancer has continued to grow - Your life expectancy is at least 3 months - Your general health and blood counts are within acceptable ranges **You may NOT be eligible if...** - You have not had prior treatment - You have serious organ dysfunction (heart, lung, liver, or kidney) - You are pregnant - You have active serious infections Talk to your doctor to see if this trial is right for you.