An Imaging Study in ER Negative Breast Cancer by Targeting αvβ6

Inclusion Criteria: 1. Able to give written informed consent prior to admission to this study. 2. Female aged ≥18 years. 3. ECOG performance status of 0-2. 4. Histologically confirmed ER-ve metastatic or locally advanced breast cancer (latest available sample). ER-ve status defined as \<1% of tumour cells positive for ER on IHC or IHC score (Allred) ≤2. Any HER2 status is acceptable. 5. At least one metastatic tumour site measuring ≥1cm in the longest diameter (except lymph nodes which must have a short axis of ≥1.5cm) as assessed by clinical imaging or by physical clinical evaluation. 6. Biopsiable metastatic or locally advanced tumour sites, if a FFPE sample of current metastatic sites is not available. If an FFPE sample from the current metastatic sites is not available then patients must be willing to undergo an US or CT guided biopsy. 7. Available FFPE tumour sample of the primary tumour prior to study entry for central assessment. 8. Known αvβ6 status on primary or metastatic tumour (latest available) as defined by IHC. 9. Patient must be progressing on current anti-cancer treatment (non-responder). 10. Haematologic indices (FBC, WBC, ANC, platelets count and haemoglobin) and biochemical indices (sodium, potassium, chloride, urea, creatinine, total protein, albumin, total bilirubin, ALP and AST) within local institutional limits. 11. Negative serum or urine pregnancy test for female patients of childbearing potential prior to study entry . Female patients of childbearing potential must agree to use adequate contraception as described in the protocol from the day of the scan and until 4 weeks after the last scan. Exclusion Criteria: 1. Breast-feeding female patients. 2. Previous or current exposure to animals that may harbour the foot and mouth disease virus FMDV2 3. Previous long-term (≥ 3 months) residence in a country where FMDV2 is endemic (such as certain areas of Africa, Asia and South America). 4. Planned to receive further anti-cancer treatment while on study. 5. Subject feels unable to lie flat and still on their back for a period of up to 95 minutes in the PET/CT scanner. 6. Any other disease, metabolic dysfunction, physical examination finding, or clinical laboratory finding that, in the investigator's opinion, gives reasonable suspicion of a disease or condition that contraindicates the use of the tracer, may affect the interpretation of the results, render the patient at high risk from treatment complications or interferes with obtaining informed consent.