PhII Randomized CAPecitabine + ELAcestrant vs. Capecitabine Alone in ER+ Breast Cancer (CAPELA)

This study (CAPELA) is testing whether adding a hormone-blocking drug called elacestrant to the chemotherapy capecitabine works better than capecitabine alone in people with estrogen receptor-positive, HER2-negative advanced breast cancer who also have a specific genetic mutation in the ESR1 gene. **You may be eligible if...** - You have estrogen receptor-positive (ER+), HER2-negative advanced or metastatic breast cancer - Your tumor has been tested and has one of several qualifying ESR1 gene mutations - You are 18 or older - Standard testing confirms your ER and HER2 status **You may NOT be eligible if...** - Your tumor is HER2-positive or ER-negative - You do not have an ESR1 mutation, or your ESR1 testing result is more than 2 months old - You have not received prior hormone therapy (endocrine therapy) for your metastatic disease Talk to your doctor to see if this trial is right for you.