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

Exclusion Criteria

• •Patient who received any CDK4/6 inhibitor.
• •Patient has a known hypersensitivity to any of the excipients of LEE011 or letrozole
• •Patients with inflammatory breast cancer.
• •Patient who received any prior systemic anti-cancer therapy (including hormonal therapy and chemotherapy) for advanced breast cancer
• •Patient is currently using other anti-cancer therapy
• •Patient has had major surgery within 14 days prior to starting study drug or has not recovered from major side effects.
• •Patient who has received radiotherapy ≤ 4 weeks
• •Patient has a concurrent malignancy or malignancy within 3 years
• •Patient has metastases to the central nervous system (CNS).
• •Patient has a known history of HIV infection