MONA-7: A Phase III Randomized, Double-blind, placebo-controlled study of MONA-7: LEE011 or Placebo in Combination with Tamoxifen and Goserelin or a Non-Steroidal Aromatase Inhibitor (NSAI) and Goserelin for the Treatment of Premenopausal Women with Hormone Receptor Positive, HER 2-Negative, Advanced Breast Cancer