Inclusion Criteria:

- Histological diagnosis of breast cancer

- Indication for hormonal therapy (ER and/or PgR positive)

- Stage IV disease

- Female gender

- Postmenopausal status (patients treated with LHRH analogs are eligible for the Phase
II part of the study)

- At least one target or non-target lesion according to RECIST criteria

- ECOG Performance Status 0-2

- Adequate bone marrow (neutrophils > or = 1.500/mm³, platelets > or = 100.000/mm³ and
hemoglobin > or = 9 g/dl), hepatic (GOT, GPT < 2.5 e bilirubin <1.25 times the value
of upper normal limit) and renal (creatinine < 1.25 times the value of upper normal
limit) function

- Adequate cardiac function (FEVS > or = 50%)

- Able to take oral medications

- Life expectancy > 3 months

- Signed informed consent

Exclusion Criteria:

- Any previous hormone therapy for metastatic disease

- More than one line of chemotherapy for metastatic disease (first line chemotherapy is
permitted)

- Symptomatic cerebral metastases

- Planned concomitant radiation therapy in the first month of therapy (for those
patients participating in the dose finding phase of the study)

- Previous therapy with exemestane, including as adjuvant therapy (previous therapy
with non-steroidal aromatase inhibitors is permitted)

- Previous or concurrent malignancy in past 5 years (excluding adequately treated basal
cel or spinocellular skin cancer and in situ carcinoma of the cervix)

- Treatment with experimental pharmacologic therapy within 4 weeks of enrollment in the
study

- Unable or unwilling to provide signed informed consent

- Any concurrent illness that would, in the Investigator's opinion, contraindicate the
use of the study drugs.

- Active infection

- Assumption of CYP3A4 inhibitors or inducers (ketoconazole, itraconazole,
fluconazole, macrolide antibiotics, antidepressives, calcium-antagonists, cimetidine,
carbamazepine, phenytoin, barbiturates, rifampicin e glucocorticoids)

- Pregnancy or lactation

- Unable to comply with follow-up

- Active hepatobiliary disease (with the exception of Gilbert's syndrome, asymptomatic
biliary calculi, hepatic metastases or stabile chronic hepatopathy)