Kepalb^® Palbociclib Capsuless are an oral CDK4/6 inhibitor that selectively targets and inhibits the activity of the CDK4/6-Cyclin D1 complex. This prevents tumor cells from passing through the G1 to S phase checkpoint, blocking the cell cycle and inhibiting tumor cell proliferation. It is primarily used for the treatment of hormone receptor-positive (HR+), HER2-negative locally advanced or metastatic breast cancer, in combination with aromatase inhibitors as initial endocrine therapy for postmenopausal women. In August 2022,it was approved by NMPA and listed as a Category B product under the national medical insurance program. As the first CDK4/6 inhibitor approved for breast cancer, Palbociclib enhances the efficacy of endocrine therapy, delays the onset of endocrine resistance, and significantly improves patient survival. It is recommended as a first-line standard treatment in both domestic and international guidelines.