Study of LEE011, BYL719 and Letrozole in Advanced ER+ Breast Cancer

Inclusion Criteria:

Postmenopausal, Estrogen-receptor positive and/or Progesterone-receptor positive breast cancer
Phase Ib dose escalation only: Any number of prior lines of endocrine therapy is allowed with the exception of cytotoxic therapy which is limited to one prior line administered in the advanced (metastatic or locally advanced) setting.
Phase Ib dose expansions Arms 1, 2 and 3
No prior systemic treatment in the advanced (metastatic or locally advanced) setting with the exception of treatment with letrozole for a maximum of one month prior to starting study treatment.
Patients who received (neo)adjuvant therapy for breast cancer are eligible. Prior therapy with letrozole or anastrozole in the (neo)adjuvant setting is permitted if the disease-free interval is greater than 12 months from the completion of treatment.

Exclusion Criteria:

HER2-overexpression in the patient's tumor tissue
Patients with active CNS or other brain metastases
Major surgery within 2 weeks
Acute or chronic pancreatitis
Bilateral diffuse lymphangitic carcinomatosis
Another malignancy within 3 years
Receiving hormone replacement therapy that cannot be discontinued
Impaired cardiac function
Patients with clinically manifest diabetes mellitus (treated and/or clinical signs or with fasting glucose ≥ 126 mg/dL / 7.0 mmol/L or hemoglobin A1c >6.5%), history of gestational diabetes mellitus or documented steroid-induced diabetes mellitus.
Other protocol-defined inclusion/exclusion criteria may apply