BACKGROUND
The current study aims to assess the safety, pharmacokinetics, feasibility, and reproducibility of immunoPET imaging with copper-64 (64Cu)-trastuzumab.
METHODS
An i.v. injection of 296-370MBq/5mg 64Cu-trastuzumab was administered between 1 to 4 h after routine trastuzumab treatment. Whole-body PET scans were performed immediately post-injection and at 24 h post-injection. Serial pharmacokinetics were performed. Of 11 patients (median age of 52; range of 31-61), 8 underwent a repeat study with 64Cu-trastuzumab to assess image and pharmacokinetic reproducibility. Patients were monitored for toxicity.
RESULTS
Patients experienced no allergic reactions or significant adverse effects from 64Cu- trastuzumab. Eight patients successfully completed a repeat 64Cu-trastuzumab study, with acceptable reproducibility of both the biodistribution and pharmacokinetic clearance. Study 1 vs. study 2 showed similar serum concentration post-injection (mean 42.4 + 7.8 %ID/L vs. 44.7 + 12.6 %ID/L) and similar T1/2 (single exponential 46.1 vs. 44.2 h), p>0.5. The volume of distribution (median 2.50L) was in the range reported for trastuzumab and close to the estimated plasma volume of 2.60L. Of 11 patients, 2 had 64Cu-trastuzumab localization corresponding to known tumor sites-1 in liver and 1 in breast.
CONCLUSIONS
Preliminary results suggest that scanning with 64Cu-trastuzumab is feasible, safe, and reproducible. Tumor uptake of 64Cu-trastuzumab was observed, but tumor detection exhibited low sensitivity in this study in which imaging was performed in the presence of trastuzumab therapy.