Phase III Study of Palbociclib (PD-0332991) in Combination With Exemestane Versus Chemotherapy (Capecitabine) in Hormonal Receptor (HR) Positive/HER2 Negative Metastatic Breast Cancer (MBC) Patients With Resistance to Non-steroidal Aromatase Inhibitors (P

This is an international, multicenter, open label, controlled, randomized phase III study comparing the efficacy and safety of palbociclib in combination with exemestane versus capecitabine in postmenopausal women with HR positive/HER2 negative MBC whose disease was refractory to previous non-steroidal aromatase inhibitors (NSAI: letrozole or anastrozole), defined as recurrence while on or within 12 months after the end of adjuvant treatment or progression while on or within 1 month after the end of treatment for advanced disease. It is not mandatory to have letrozole or anastrozole as the most recent treatment before randomization but progression while receiving the most recent systemic therapy had to be documented before randomization. Patients must have measurable disease or lytic bone lesions in the absence of measurable disease. Approximately 348 patients will be randomized 1:1 between the experimental arm (Arm A: approximately 174 patients treated with palbociclib plus exemestane) and the control arm (Arm B: approximately 174 patients treated with capecitabine).

The study hypothesis is to demonstrate that palbociclib in combination with exemestane is superior to capecitabine in prolonging Progression-Free Survival (PFS) in postmenopausal women with HR positive/HER2 negative MBC whose disease was resistant to non-steroidal aromatase inhibitors.