Indications
Palbociclib is a kinase inhibitor used to treat advanced or metastatic breast cancer that is hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative. It is given in combination with other medicines, in one of two ways. In postmenopausal women, it is used with an aromatase inhibitor as the first endocrine-based therapy. In women whose disease has progressed after endocrine therapy, it is used with fulvestrant.
⚠️ Always consult a registered physician before taking any medicine.
Pharmacology
Palbociclib is an inhibitor of Cyclin-dependent kinases (CDK) 4 and 6. Cyclin D1 and CDK4/6 sit downstream of the signaling pathways that lead to cells multiplying. In Estrogen receptor (ER)-positive breast cancer cell lines, Palbociclib reduced cell proliferation by blocking the cell's progression from G1 into S phase of the cell cycle.
When breast cancer cell lines were treated with Palbociclib together with antiestrogens, retinoblastoma (RB) protein phosphorylation went down. This led to reduced E2F expression and signaling, and more growth arrest than either drug gave alone. In ER-positive breast cancer cell lines, the same combination also increased cell senescence compared to each drug alone. That effect was sustained for up to 6 days after Palbociclib was removed, and it was greater if the antiestrogen treatment was continued.
In vivo studies used a patient-derived ER-positive breast cancer xenograft model. They showed that Palbociclib combined with letrozole increased the inhibition of RB phosphorylation, downstream signaling and tumor growth, compared to each drug alone.
Pregnancy & Breastfeeding
Palbociclib can harm an unborn baby when it is given to a pregnant woman. Pregnant women should be told about this possible risk to the baby. In pregnancies that are clinically recognized, the risk of major birth defects is 2%-4% and the risk of miscarriage is 15%-20%.
⚠️ Talk to your doctor before taking any medicine during pregnancy or while breastfeeding.
Dosage Reference
⚠️ Reference ranges from official sources only. Consult your doctor for personalized dosing.
Side Effects & Interactions
Side Effects
No side-effect data recorded yet.