New biomarker and strategy identify and overcome resistance in HR+/HER2- breast cancer
MD Anderson Research Highlight August 04, 2025
CDK4/6 inhibitors are targeted therapies commonly used as first-line treatments for patients with hormone receptor-positive HER2-negative (HR+/HER2-) metastatic breast cancer. However, some patients stop responding to CDK4/6 inhibitors, and the mechanisms behind this acquired resistance are poorly understood. In a new study led by , researchers discovered that the inflammatory protein IL-6 becomes elevated in these patients, which then triggers another protein ¨C STAT3 ¨C that helps tumors progress. This highlights the potential of monitoring IL-6 levels, which are easily measured in blood samples, as an early predictive biomarker for CDK4/6 inhibitor resistance, allowing physicians to guide patients toward more effective treatments. Further, the researchers also demonstrated that blocking the pathway using a STAT3 inhibitor stopped or slowed tumor growth in preclinical models of resistant cancer. Learn more in
Our findings support combining IL-6 and CDK4/6 inhibitors as a novel therapeutic approach and suggest that monitoring IL-6 could guide personalized treatment in patients with resistant HR+/HER2- breast cancer.