Biomarker Analyses of Response to Cyclin-Dependent Kinase 4/6 Inhibition and Endocrine Therapy in Women with Treatment-Naïve Metastatic Breast Cancer

These data underscore the importance of CDK4/6 signaling in HR+/HER2- breast cancer and suggest that the interplay between steroid hormone and peptide growth factor signaling could drive dependence on CDK4/6 signaling.<i>See related commentary by Anurag et al., p. 3</i>.