What does Palbociclib capsules do?

Palbociclib (Palbociclib)is an inhibitor of cyclin-dependent kinases (CDK) 4 and 6. Cyclin D1 and CDK4/6 are downstream of signaling pathways leading to cell proliferation. In vitro, palbociclib reduces cell proliferation in estrogen receptor (ER)-positive breast cancer cell lines by preventing cells from entering the S phase of the cell cycle from G1. Treatment of breast cancer cell lines with the combination of palbociclib and antiestrogen resulted in reduced retinoblastoma (Rb) protein phosphorylation, resulting in reduced E2F expression and signaling, and increased growth arrest compared to treatment with each drug alone.