Synthesis and Analysis of Cu-64-Labeled GE11-Modified Polymeric Micellar Nanoparticles for EGFR-Targeted Molecular Imaging in a Colorectal Cancer Model

Polymeric micellar nanoparticles represent versatile and biocompatible platforms for targeted drug delivery. However, tracking their biodistribution, stability, and clearance profile in vivo is challenging. The goal of this study was to prepare surfacemodified micelles with peptide GE11 for targeting the epidermal growth factor receptor (EGFR). In vitro fluorescence studies demonstrated significantly higher internalization of GE11 micelles into EGFR-expressing HCT116 colon cancer cells versus EGFRnegative SW620 cells. Azo coupling chemistry of tyrosine residues in the peptide backbone with aryl diazonium salts was used to label the micelles with radionuclide Cu-64 for positron emission tomography (PET) imaging. In vivo analysis of Cu-64-labeled micelles showed prolonged blood circulation and predominant hepatobiliary clearance. The biodistribution profile of EGFR-targeting GE11 micelles was compared with nontargeting HW12 micelles in HCT116 tumor-bearing mice. PET revealed increasing tumor-to-muscle ratios for both micelles over 48 h. Accumulation of GE11-containing micelles in HCT116 tumors was higher compared to HW12-decorated micelles. Our data suggest that the efficacy of image-guided therapies with micellar nanoparticles could be enhanced by active targeting, as demonstrated with cancer biomarker EGFR.