Inclusion Criteria:

- Adult women (≥ 18 years of age) with metastatic or locally advanced breast cancer not
amenable to curative treatment by surgery or radiotherapy.

- Histological or cytological confirmation of estrogen-receptor positive (ER+) breast
cancer

- Postmenopausal women.

- Disease refractory to non steroidal aromatase inhibitors (NSAI),

- Radiological or objective evidence of recurrence or progression on or after the last
systemic therapy prior to randomization.

- Patients must have at least one lesion that can be accurately measured or bone
lesions in the absence of measurable disease

- Adequate bone marrow and coagulation function

- Adequate liver and renal function

- ECOG Performance Status = 2 or less

Exclusion Criteria:

- HER2-overexpressing patients

- Patients with only non-measurable lesions other than bone metastasis (e.g. pleural
effusion, ascites etc.).

- Patients who received more than one chemotherapy line for Advanced Breast Cancer.

- Previous treatment with exemestane or mTOR inhibitors.

- Known hypersensitivity to mTOR inhibitors, e.g. sirolimus (rapamycin).

- Radiotherapy within four weeks prior to randomization

- Currently receiving hormone replacement therapy,

- Patients receiving immunosuppressive agents or chronic corticosteroids use

- Patients being treated with strong inhibitors or inducers of CYP3A within 5 days
prior to randomization

Other protocol-defined inclusion/exclusion criteria may apply