RT Journal Article SR Electronic T1 Tumor Uptake of 64Cu-DOTA-Trastuzumab in Patients with Metastatic Breast Cancer JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 38 OP 43 DO 10.2967/jnumed.117.193888 VO 59 IS 1 A1 Joanne E. Mortimer A1 James R. Bading A1 Jinha M. Park A1 Paul H. Frankel A1 Mary I. Carroll A1 Tri T. Tran A1 Erasmus K. Poku A1 Russell C. Rockne A1 Andrew A. Raubitschek A1 John E. Shively A1 David M. Colcher YR 2018 UL http://jnm.snmjournals.org/content/59/1/38.abstract AB The goal of this study was to characterize the relationship between tumor uptake of 64Cu-DOTA-trastuzumab as measured by PET/CT and standard, immunohistochemistry (IHC)-based, histopathologic classification of human epidermal growth factor receptor 2 (HER2) status in women with metastatic breast cancer (MBC). Methods: Women with biopsy-confirmed MBC and not given trastuzumab for 2 mo or more underwent complete staging, including 18F-FDG PET/CT. Patients were classified as HER2-positive (HER2+) or -negative (HER2−) based on fluorescence in situ hybridization (FISH)–supplemented immunohistochemistry of biopsied tumor tissue. Eighteen patients underwent 64Cu-DOTA-trastuzumab injection, preceded in 16 cases by trastuzumab infusion (45 mg). PET/CT was performed 21–25 (day 1) and 47–49 (day 2) h after 64Cu-DOTA-trastuzumab injection. Radiolabel uptake in prominent lesions was measured as SUVmax. Average intrapatient SUVmax (<SUVmax>pt) was compared between HER2+ and HER2− patients. Results: Eleven women were HER2+ (8 immunohistochemistry 3+; 3 immunohistochemistry 2+/FISH amplified), whereas 7 were HER2− (3 immunohistochemistry 2+/FISH nonamplified; 4 immunohistochemistry 1+). Median <SUVmax>pt for day 1 and day 2 was 6.6 and 6.8 g/mL for HER 2+ and 3.7 and 4.3 g/mL for HER2− patients (P < 0.005 either day). The distributions of <SUVmax>pt overlapped between the 2 groups, and interpatient variability was greater for HER2+ than HER2− disease (P < 0.005 and 0.001, respectively, on days 1 and 2). Conclusion: By 1 d after injection, uptake of 64Cu-DOTA-trastuzumab in MBC is strongly associated with patient HER2 status and is indicative of binding to HER2. The variability within and among HER2+ patients, as well as the overlap between the HER2+ and HER2− groups, suggests a role for 64Cu-DOTA-trastuzumab PET/CT in optimizing treatments that include trastuzumab.