CDK4/6 Inhibitors Combined With Standard Adjuvant Endocrine Therapy in High-Risk, HR+/HER2+ Early Breast Cancer Patients(CHESS)

This trial tests whether adding a CDK4/6 inhibitor to standard hormone therapy helps women with high-risk HR-positive, HER2-positive early breast cancer after completing anti-HER2 treatment. **You may be eligible if...** - You are a woman aged 18–70 with HR-positive, HER2-positive invasive breast cancer - You had a mastectomy and have positive lymph nodes or other high-risk features - You completed anti-HER2 therapy (trastuzumab, T-DM1, or TKI) within the past year - Your blood counts and organ function meet required levels **You may NOT be eligible if...** - You have another active malignancy - You are pregnant or breastfeeding - Your heart, liver, or kidney function does not meet study criteria Talk to your doctor to see if this trial is right for you.