An Open-label, Multicenter Phase II Study to Assess the Response of Subjects With Metastatic Breast Cancer Previously Treated With Anthracycline and Taxane Therapy With or Without Capecitabine to ZD6474 (100-mg or 300-mg Daily Oral Dose).

Inclusion Criteria:

- Histological and/or cytological confirmation of metastatic breast cancer which is
refractory to anthracycline, taxane, with or without capecitabine therapies;

- WHO performance status 0, 1 or 2 on the day of registration;

- Females, aged >= 18 years;

- No Gastrointestinal pathology which could affect the bioavailability of ZD6474.

Exclusion Criteria:

- Any evidence of severe or uncontrolled systemic diseases including known cases of
Hepatitis B or C or human immunodeficiency virus (HIV).

- Significant cardiac event (including symptomatic heart failure or unstable angina)
within 3 months of entry or any cardiac disease that in the opinion of the
investigator increases risk for ventricular arrhythmia;

- History of clinically significant cardiac arrhythmia (multifocal PVCs, bigeminy,
trigeminy, ventricular tachycardia), which is symptomatic or requires treatment (CTC
grade 3) or asymptomatic sustained ventricular tachycardia;

- Chronic atrial fibrillation;

- Previous history of QT / QTc prolongation with other medication;

- Congenital long QT syndrome;

- Systemic anti-cancer therapy or other investigational agent within the last 4 weeks
(6 weeks for nitrosoureas, mitomycin C, or suramin);

- Currently receiving drugs with known significant 3A4 inhibitory (ie, ketoconazole,
itraconazole, troleandomycin, erythromycin, diltiazem, verapamil) or stimulatory (ie,
phenytoin, carbamazepine, barbiturates, rifampicin) effects;

- Currently receiving therapeutic doses of warfarin (Coumadin?)