Palbocicril, the first cyclin-dependent kinases 4 and 6 inhibitors, is a crucial milestone in the development history of antineoplastic drugs. It combined with aromatase inhibitor or fulvestrant as first-line, second-line or post-line therapy has good efficacy and safety for hormone receptor-positive, human epidermal growth factor receptor-2 negative locally advanced or metastatic breast cancer, which has a good application prospect. This article summarizes the clinical trials and safety studies related to palbociclib.