A Phase Ib Dose Escalation Study of the Combination of LEE011 With Letrozole and Dose Expansion of LEE011 With Hormonal Therapy for the Treatment of Pre-(With Goserelin) and Postmenopausal Women With Hormone Receptor Positive, HER2-negative, Advanced Breast Cancer

The purpose of the Phase Ib is to: 1. determine the recommended dose of LEE011 in combination with a standard dose of letrozole as well as to provide additional safety and anti-tumor activity data in Asian non-Japanese patients 2. determine the recommended dose of LEE011 in combination with a standard dose of letrozole as well as to provide additional safety and activity data in Japanese patients 3. evaluate the safety and anti-tumor activity of LEE011 at the RP2D established in the dose escalation part in combination with a standard dose of letrozole, fulvestrant or tamoxifen plus goserelin in Japanese patients.