Immune Therapy in HR-positive/HER2-negative Metastatic Breast Cancer(ENIGMA)-BCTOP-L-M02

This study is testing immunotherapy combinations in women with a specific subtype of hormone receptor-positive, HER2-negative metastatic breast cancer — a subtype identified by a molecular profiling test called SNF-2. Researchers want to see if adding immunotherapy to standard hormone-blocking treatment improves outcomes. **You may be eligible if...** - You are a woman between 18 and 75 years old - You have been diagnosed with hormone receptor-positive (HR+), HER2-negative metastatic breast cancer - Your tumor is classified as SNF-2 subtype by specialized testing - Your cancer has progressed or you require a new line of treatment **You may NOT be eligible if...** - Your tumor is not the SNF-2 subtype - Your cancer is HER2-positive - You have active autoimmune disease - Your organ function is inadequate Talk to your doctor to see if this trial is right for you.