Palbociclib is used in the treatment of breast cancer. It is also used to treat patients with certain types of breast cancer (estrogen receptor-positive, human epidermal growth factor receptor 2-negative) which have spread to other organs. It is given together with hormonal anticancer therapies.

Palbociclib is an anti-cancer medication. Cyclin dependent kinase 4 and 6 (chemical messengers) are downstream of signaling pathways which lead to the proliferation of cells. This medicine works by inhibiting cyclin dependent kinase 4 and 6, thus arrests the cancer cell cycle (cell growing process). It also targets the estrogen (hormone) receptor-positive breast cancer cells by disrupting the cell cycle.

Fatigue, Hair loss, Rash, Vomiting, Diarrhea, Nausea, Decreased appetite, Infection, Decreased white blood cell count, Stomatitis (Inflammation of the mouth), Anemia (low number of red blood cells), Weakness, Fever