Fulvestrant as Maintenance Therapy After First-line Chemotherapy in HER2 - Postmenopausal MBC Patients

Inclusion Criteria:

1. Histologically or cytologically diagnosis of breast cancer;
2. Presence of metastatic disease either measureable or non-measureable but evaluable bone disease as defined by the Response Evaluation Criteria in Solid Tumors;
3. Diagnosis of hormone receptor positive (HR+), HER2 negative breast cancer. To fulfill the requirement for HR+ disease, a breast cancer must express, by immunohistochemistry (IHC), at least one of the hormone receptors (estrogen receptor \[ER\], progesterone receptor \[PR\]). To fulfill the requirement for HER2 negative disease, a breast cancer must not demonstrate over-expression of HER2 by either IHC or fluorescence in-situ hybridization (FISH);
4. Post-menopausal status at the time of randomization.
5. Previous treatment with either an antiestrogen or an aromatase inhibitor for adjuvant or metastatic disease is allowed;
6. Age \>18;
7. One line chemotherapy for metastatic disease discontinued for 21-28 days. Patient has to have response or stability from the first-line chemotherapy. The patient may have received prior systemic chemotherapy in the neo-adjuvant or adjuvant setting;
8. Patients with measurable or evaluable disease according to Response Evaluation Criteria in Solid Tumors (RECIST) criteria;
9. Performance Status (ECOG) \<2;
10. No brain metastases;
11. No clinically serious concurrent illnesses;
12. Adequate organ function
13. Use of bisphosphonates are allowed;
14. Use of antiangiogenetic drugs (bevacizumab associated to paclitaxel) is allowed, but discontinued 21-28 days before start study;
15. Life expectancy \> 12 weeks;
16. Are willing to participate for the duration of the study and to follow study procedures;
17. Written informed consent prior to any study-specific procedures Written informed consent;

Exclusion Criteria:

1. Treatment with a drug that has not received regulatory approval for any indication within 21-28 days from the randomization;
2. Drug (chemotherapy or biological drug) after the end of first-line chemotherapy for maintenance phase;
3. Significant known cardiovascular impairment (NYHA CHF \> grade 2, unstable angina, myocardial infarction within the previous 6 months prior to randomization, or existing serious cardiac arrhythmia). VECF (Ventricular Ejection Cardiac Fraction) ≤ 50%;
4. Prior malignancy (other than breast cancer) except for non-melanoma skin cancer and carcinoma in situ (of the cervix or bladder), unless diagnosed and definitively treated more than 5 years prior to randomization;
5. Severe/uncontrolled intercurrent illness within the previous 28 days prior to randomization.
6. Any other significant co-morbid conditions that in the opinion of the Investigator would impair study participation or cooperation;
7. Patients with psychiatric illness, social situation or geographical situation that would preclude informed consent or limit compliance with study requirements, as determined by the Investigator;