PSMA-PET/CT to Assess the Expression of Specific Membrane Antigen (PSMA) in Patients With Progressive Triple-negative Breast Cancer.

Inclusion Criteria: * Written informed consent in accordance with institutional guidelines and obtained prior to any study procedure * Women with ≥ 18 years-old * Eastern Cooperative Oncology Group Performance Status of 0 to 2 * Confirmed diagnosis of progressive metastatic TNBC and presenting measurable disease on 18F-FDG PET/CT (performed within 2 weeks) or Brain MRI in case of progressive brain metastases (performed within 4 weeks) prior to PSMA PET/CT. * Radiolabelled PSMA PET/CT has to be performed before the next treatment line initiation Exclusion Criteria: * Pregnant or lactating patients * Other active neoplastic disease * Treatment by another molecule that is the object of investigation within 30 days * Skin only metastatic disease * Patients with a significant medical, neuro-psychiatric, or surgical condition, which, in the investigator's opinion, may interfere with completion of the study