Introduction
toxicity, HER2-negative, HR-positive, breast cancer
BREAST CANCER
Cyclin D-cyclin-dependent kinase 4 and 6 (CDK4/6) axis is known to play a key role in the cell cycle and its dysregulation is one of the central mechanisms of breast cancer (BC) biologyDalpiciclib (SHR6390) is a highly selective, small molecule CDK4/6 inhibitor, recently approved for HR-positive, HER2-negative ABC in China, based on impressive efficacy and manageable toxicity in a randomized phase 3 DAWNA‐1 trialOur study aims to investigate the dual-oral regimen of dalpiciclib and pyrotinib, a CDK4/6 inhibitor and a HER2 TKI without a backbone of chemotherapy or endocrine therapy, in HER2-positive ABC patients irrespective of HR status. Here we report the results.