Ibrance (palbociclib) is a targeted cancer therapy belonging to the class of cyclin-dependent kinase (CDK) 4/6 inhibitors. It works by blocking CDK4 and CDK6 proteins, which play a key role in promoting the growth and division of cancer cells. By inhibiting these enzymes, Ibrance helps slow the progression of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced or metastatic breast cancer.

It is typically prescribed in combination with aromatase inhibitors (such as letrozole) as initial endocrine-based therapy, or with fulvestrant in patients who have disease progression following endocrine therapy. Ibrance is taken orally in cycles, usually 21 days on treatment followed by 7 days off. Common side effects include low white blood cell counts (neutropenia), fatigue, nausea, infections, and hair thinning.

Ibrance offers a significant treatment option for postmenopausal women and men with HR+/HER2- breast cancer, helping to extend progression-free survival when used as part of a comprehensive treatment plan.