Phase Ib Trial of LEE011 With Everolimus (RAD001) and Exemestane in the Treatment of Hormone Receptor Positive HER2 Negative Advanced Breast Cancer

Inclusion Criteria: * Adult women (≥ 18 years of age) with metastatic or locally advanced breast cancer * Histological or cytological confirmation of ER+ breast cancer in dose escalation and HR+ breast cancer in dose expansion * A representative tumor specimen must be available for molecular testing. * Postmenopausal women. Postmenopausal status is defined either by: * Age ≥ 18 with prior bilateral oophorectomy * Age ≥ 60 years * Age \<60 years with amenorrhea for at least 12 months and both follicle-stimulating hormone (FSH) and estradiol levels are in postmenopausal range (according to the local laboratory) * Recurrence while on, or within 12 months of end of adjuvant treatment with letrozole or anastrozole, or * Progression while on, or within one month of end of letrozole or anastrozole treatment for locally advanced or metastatic breast cancer. * Patients must have: * Measurable disease\*: At least one lesion that can be accurately measured in at least one dimension ≥ 20 mm with conventional imaging techniques or ≥ 10 mm with spiral CT or MRI or * Bone lesions: lytic or mixed (lytic + sclerotic) in the absence of measurable disease as defined above. * ECOG Performance Status 0-1. * Fasting serum cholesterol ≤ 300 mg/dl or 7.75 mmol/L and fasting triglycerides ≤ 2.5 × ULN. In case one or both of these thresholds are exceeded, the patient can only be included after initiation of statin therapy and when the above mentioned values have been achieved * Standard 12-lead ECG values defined as the mean of the triplicate ECGs and assessed by the central laboratory. * QTcF interval at screening \< 450 msec (using Fridericia's correction). * Resting heart rate 50-90 bpm Exclusion Criteria: * HER2-overexpressing patients by local laboratory testing (IHC 3+ staining or in situ hybridization positive). * Patients who received more than one chemotherapy line for advanced breast cancer. * Previous treatment with exemestane or mTOR inhibitors\* (Note: Patients with disease refractory to prior LEE011 are excluded for dose expansion Group 3 only). * History of brain or other CNS metastases. * Clinically significant, uncontrolled heart disease and/or recent cardiac repolarization abnormality including any of the following: * History of myocardial infarction (MI), angina pectoris, symptomatic pericarditis, or coronary artery bypass graft (CABG) within 6 months prior to study entry * Documented cardiomyopathy * Left ventricular ejection fraction (LVEF) \< 50% as determined by Multiple Gated acquisition scan (MUGA) or echocardiogram (ECHO) * Long QT syndrome or family history of idiopathic sudden death or congenital long QT syndrome, and etc. * Clinically significant cardiac arrhythmias, complete left bundle branch block, high-grade AV block * Systolic Blood Pressure (SBP) \>160 or \<90 mmHg * Patients who are currently receiving treatment with agents that are known to cause QTc prolongation in humans * Patients who are currently receiving treatment (within 7 days prior to starting study treatment) with strong and moderate inhibitors or inducers of CYP3A4/5, substrates of CYP3A4/5 with a narrow therapeutic index or Herbal preparations/medications (Refer to Section 6.4 and Appendix 3) Inclusion Criteria Exceptions for Phase Ib Dose Expansion patients: Dose Expansion part of the study has 3 groups, following are the Inclusion Criteria exceptions for these 3 groups 1. Group 1 - Patients must not have received prior treatment with any CDK4/6 inhibitors 2. Group 2 - Patients must have disease progression while on or within one month after CDK4/6 inhibitor based therapy 3. Group 3 - Patients must have disease progression while on or within one month after CDK4/6 inhibitor based therapy (except those patients who received prior LEE011 based therapy). Other protocol-defined Inclusion/Exclusion may apply.