A Pharmacodynamics Pre-surgical Study of LEE011 in Early Breast Cancer Patients (MONALEESA-1)

Inclusion Criteria: * Female patient is ≥ 18 years old at the time of informed consent, with newly diagnosed resectable breast cancer, who received no prior therapy for breast cancer * Patient is postmenopausal. Postmenopausal status is defined either by: * Prior bilateral oophorectomy * Age ≥60 * Age \<60 and amenorrhea for 12 or more months and FSH (Follicle Stimulating Hormone) and estradiol in the postmenopausal range. * Patient has a histologically (and/or cytologically) confirmed diagnosis of estrogen-receptor positive and/or progesterone receptor positive breast cancer by local laboratory. * Patient has a grade II or grade III invasive breast cancer * Patient has Human Epidermal Growth Factor Receptor 2 (HER2) negative breast cancer defined as a negative in situ hybridization test or an Immunohistochemistry (IHC) status of 0, 1+ or 2+ (if IHC 2+, a negative in situ hybridization (respectively FISH/CISH/SISH) test is required) by local laboratory testing * Patient has at least one breast lesion with a diameter of ≥1.0 cm by the most accurate imaging modality used. * Patient has an Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1 Exclusion Criteria: * Patient has received any prior therapy for breast cancer. * Patient has a concurrent malignancy or malignancy within 3 years of randomization, with the exception of adequately treated, basal cell skin cancer or squamous cell carcinoma, non-melanomatous skin cancer or curatively resected cervical cancer. * Patient has active cardiac disease or a history of cardiac dysfunction including any of the following: * History of angina pectoris, symptomatic pericarditis, or myocardial infarction within 12 months prior to study entry * History of documented congestive heart failure (New York Heart Association functional classification III-IV) * Documented cardiomyopathy * Patient has a Left Ventricular Ejection Fraction (LVEF) \< 50% as determined by Multiple Gated acquisition (MUGA) scan or echocardiogram (ECHO) * History of ventricular, supraventricular, nodal arrhythmias, or any other cardiac arrhythmias, Long QT Syndrome or conduction abnormality in the previous 12 months. * Family history of QTc prolongation or of unexplainable sudden death at \<50 years of age. * On screening 12 lead ECG, any of the following cardiac parameters: bradycardia (heart rate \< 50 at rest), tachycardia (heart rate \> 90 at rest), PR interval \> 220 msec, QRS interval \>109 msec, or QTcF \>450 msec. * Systolic blood pressure \>160 mmHg or \<90 mmHg. * Patient is currently receiving any of the following medications (see Appendix 1 for details): * That are known strong inducers or inhibitors of CYP3A4. * That have a narrow therapeutic window and are predominantly metabolized through CYP3A4. * That have a known risk to prolong the QT interval or induce Torsades de Pointes. Other protocol-defined inclusion/exclusion criteria may apply