Palbociclib Combined With Fulvestrant in HR-Positive, HER2-Negative Metastatic Breast Cancer After Endocrine Failure.  Multicenter, Randomized, Double-Blind, Placebo Controlled, Phase 3 Trial of Fulvestrant (Faslodex®) With or Without Palbociclib ± Goserelin in Women With HR-Positive, HER2-Negative Metastatic Breast Cancer Whose Disease Progressed After Prior Endocrine Therapy.