Inclusion Criteria

Inclusion criteria:

- Female patients ≥ 18 years of age.

- Written informed consent given.

- Histologically confirmed Stage IV breast cancer with at least one bone metastasis
radiologically confirmed.

- Previous treatment with zoledronic acid every 3-4 weeks, for 9-12 infusions over no
more than 15 months.

- Eastern Cooperative Oncology Group (ECOG) performance status ≤2 .

- Life expectancy ≥ 1 year.

Exclusion criteria:

- More than 3 months since last infusion of Zoledronic Acid (Zometa®).

- Treatments with other bisphosphonate than Zoledronic Acid (Zometa®) at any time prior
to study entry.

- Serum creatinine > 3 mg/dL (265 μmol/L) or calculated (Cockcroft-Gault formula)
creatinine clearance (CLCr) < 30 mL/min CrCl = ({[140-age (years)] x weight(kg)}/ [72
x serum creatinine (mg/dL)])x 0.85

- Corrected (adjusted for serum albumin) serum calcium < 8 mg/dl (2 mmol/L) or > 12
mg/dL ( 3.0 mmol/L).

- Current active dental problem including infection of the teeth or jawbone (maxilla or
mandibular); dental or fixture trauma, or a recurrent or prior diagnosis of
osteonecrosis of the jaw (ONJ), of exposed bone in the mouth, or of slow healing
after dental procedures.

- Recent (within 6 weeks) or planned dental or jaw surgery (e.g. extraction, implants).

- Pregnant patients (with a positive pregnancy test prior to study entry) or lactating
patients. Women of childbearing potential not using effective methods of birth
control (e.g. abstinence, oral contraceptives or implants, IUD, vaginal diaphragm or
sponge, or condom with spermicide).

- History of non-compliance to medical regimens or potential unreliable behavior.

- Known sensitivity to study drug(s) or class of study drug(s).

- Patients with severe medical condition(s) that in the view of the investigator
prohibits participation in the study

- Use of any other investigational agent in the last 30 days.