Zunsemetinib in Combination With Capecitabine in Patients With Hormone Receptor-Positive and HER2-Negative Metastatic Breast Cancer With Bone Metastasis

This trial is testing a combination of a new drug (zunsemetinib, a p38/MK2 pathway inhibitor) with a standard chemotherapy called capecitabine, for people with hormone receptor-positive, HER2-negative metastatic breast cancer that has spread to the bones. The hope is that targeting this pathway may help overcome resistance to standard therapies. **You may be eligible if...** - You are 18 or older with hormone receptor-positive, HER2-negative metastatic breast cancer and bone metastases - You have already received endocrine therapy plus a CDK4/6 inhibitor - You have not received more than one prior chemotherapy for metastatic disease - Your overall health status allows treatment (ECOG 0–2) and you have at least 12 weeks life expectancy **You may NOT be eligible if...** - You have had more than one prior chemotherapy regimen for metastatic disease - You haven't yet tried endocrine therapy with CDK4/6 inhibitor - You have serious heart, liver, or kidney problems that prevent safe treatment Talk to your doctor to see if this trial is right for you.