Background And Objectives: Palbociclib is a cyclin-dependent kinase 4/6 inhibitor that is approved in the United States for the treatment of hormone receptor‒positive (HR+)/human epidermal growth factor receptor‒2 negative (HER2-) advanced breast cancer (ABC). The objectives of this expanded access trial were to provide palbociclib in combination with letrozole to patients with HR+/HER2- ABC in Argentina, Brazil, Colombia, and Mexico who were candidates for letrozole therapy before commercial availability of palbociclib, and to evaluate the safety and tolerability of palbociclib plus letrozole.
Patients And Methods: Postmenopausal women aged ≥ 18 years with HR+/HER2- ABC were eligible to participate in this study.