PERCIST Evaluation of Trastuzumab Deruxtecan in the Treatment of HER2 Low Breast Cancer

Inclusion Criteria

• •1. Age greater than or equal to 18 years at inclusion
• •2. Cytological or histological confirmation of the diagnosis of low HER2 breast cancer (IHC 1+ or 2+ with non-amplified FISH/SIS)
• •3. Metastatic disease according to RECIST 1.1
• •4. Indication of T-DXd treatment
• •5. Patient (male or female of childbearing potential) using a highly effective contraceptive method
• •6. Women of childbearing potential must have a negative pregnancy test within 72 hours before starting treatment
• •7. Willingness and ability to comply with the visit schedule, treatment regimens, examinations and other procedures planned in the study
• •8. Patient enrolled in a health insurance plan or beneficiary of such a plan
• •9. Signed informed consent obtained before inclusion (after giving clear, fair and appropriate information)