Correlation Of Cu-64 Dota-Trastuzumab Positron Emission Tomography (Pet) Imaging With Her2 Status By Immunohistochemistry (Ihc).

618 Background: We have developed 64Cu-DOTA-trastuzumab for PET imaging of HER2-positive breast cancer. We have determined that administering trastuzumab (45 mg) prior to 64Cu-DOTA-trastuzumab sharply reduces liver uptake of the radiotracer. We are now testing whether tumor uptake of 64Cu-DOTA-trastuzumab correlates with variable IHC staining in women with advanced breast cancer. Methods: Eligibility criteria included biopsy confirmation of metastatic disease that was HER2 1+, 2+, or 3+ by IHC, no anti-HER therapy within the prior 2 mo, and at least 1 non-hepatic site of metastasis u003e 20 mm outside the biopsy site. Staging workup included 18F-FDG PET-CT. Patients received 45 mg of cold trastuzumab prior to 64Cu-DOTA-trastuzumab. PET-CT scans were obtained at 21-25 h (Day 1) and 47-48 h (Day 2) over axial fields of view chosen in reference to 18F-FDG. Uptake in prominent lesions was measured in terms of maximum single-voxel SUV (SUVmax) . Lesions identified on CT and judged to have image intensity u003e adjacen...