Abstract OT2-01-06: Phase III study of palbociclib (PD-0332991) in combination with endocrine therapy (exemestane or fulvestrant) versus chemotherapy (capecitabine) in hormonal receptor (HR) positive/HER2 negative metastatic breast cancer (MBC) patients with resistance to aromatase inhibitors.“The PEARL study”(GEICAM/2013-02)