Efficacy of Everolimus Combined With First-line Endocrine Therapy for HR+/HER2- SNF1-subtype Advanced Breast Cancer

This study is testing whether adding a drug called everolimus to standard hormone therapy helps treat a specific subtype of advanced breast cancer (called HR+/HER2- SNF1 subtype). This is for patients whose cancer has spread or cannot be removed with surgery and who have not yet received treatment for advanced disease. **You may be eligible if...** - You are between 18 and 75 years old - You have hormone receptor-positive (HR+), HER2-negative breast cancer that is locally advanced or metastatic - Your cancer has been confirmed as the SNF1 subtype by a special test - You have not previously received chemotherapy or targeted therapy for advanced or metastatic disease - You have at least one measurable tumor that has not been previously treated with radiation - Your organ function (blood counts, liver, kidneys) meets required levels **You may NOT be eligible if...** - Your cancer has spread to your brain in an uncontrolled way - You have had a serious heart condition (heart failure, heart attack) in the last 6 months - You received cancer treatment within 4 weeks before starting this study - You are pregnant or breastfeeding - You have had another cancer in the past 3 years (with some exceptions) Talk to your doctor to see if this trial is right for you.