64Cu-DOTA-Trastuzumab PET Imaging in Women with HER2-Overexpressing Breast Cancer
Abstract
Objectives. Patients with metastatic breast cancer identified as human epidermal growth factor receptor 2 (HER2)-positive (HER2+) routinely receive the anti- HER2 antibody trastuzumab plus chemotherapy. 64Cu-DOTA-trastuzumab/PET-CT has high tumor detection sensitivity in HER2+ patients [Bading, et al., JNM 2012;53 (Suppl 1):229P]. We are also imaging HER2- patients and present an initial comparison of tumor uptake between the two groups. Methods. Patients with biopsy-proven HER2+ (n=9) or HER2- (n=4) metastatic breast cancer who had not received anti-HER2 therapy for 4 mo were given trastuzumab i.v. (45 mg, to reduce liver uptake) prior to i.v. injection of 64Cu-DOTA-trastuzumab (364-512 MBq). PET-CT scans were obtained at 21-25 h (Day 1; 3-4 bed positions, 20 or 15 min each) and 47-49 h (Day 2; 1-2 bed positions, 60 or 30 min each) over fields of view based on recent (5-17 d prior) 18FFDG scans. Tumor uptake was measured as body weight-normalized SUV [maximum voxel (SUVmax) and whole-tumor (SUVwt)]. Results. For Day 1, mean SUVmax was 77% higher in lesions from HER2+ vs HER2- patients [(n, mean, median, sd, range) = (57, 7.8, 6.6, 4.3, 2.4-22.5) and (25, 4.4, 4.1, 1.1, 3.0- 6.8), respectively; p<1x10-6 by 2-tailed t test on log-transformed data]. Day 2 and SUVwt results were qualitatively the same as Day 1 SUVmax. Using median Day 1 SUVmax for a given lesion site and patient (pt), analysis for the two most common sites showed: bone [HER2+ (6 pts) 91% > HER2- (3 pts), p<0.05] and lymph nodes [HER2+ (8 pts) 54% > HER2- (3 pts), p<0.05]. Conclusions. Tumor uptake of 64Cu-DOTA-trastuzumab was higher on average in HER2+ vs HER2- patients, with significant intra-group and intra-patient variability. Our observations suggest that, by 1 d post-injection, uptake reflects binding of the radiotracer to HER2. Intra-group and intra-patient heterogeneity may have been due to variations in tumor HER2 expression, and/or other factors (blood clearance, blood-tumor transport, etc.)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 2013
- Accession Number
- ADA598708
Entities
People
- Joanne Mortimer