Development of PET Radioisotope Copper-64-Labeled Theranostic Immunoliposomes for EGFR Overexpressing Cancer-Targeted Therapy and Imaging

Combining standard surgical procedures with personalized chemotherapy and the continuous monitoring of cancer progression is necessary for effective NSCLC treatment. In this study, we developed liposomal nanoparticles as theranostic agents capable of simultaneous therapy for and imaging of target cancer cells. Copper-64 (⁶⁴Cu), with a clinically practical half-life (t_1/2 = 12.7 h) and decay properties, was selected as the radioisotope for molecular PET imaging. An anti-epidermal growth factor receptor (anti-EGFR) antibody was used to achieve target-specific delivery. Simultaneously, the chemotherapeutic agent doxorubicin (Dox) was encapsulated within the liposomes using a pH-gradient method. The conjugates of ⁶⁴Cu-labeled and anti-EGFR antibody-conjugated micelles were inserted into the doxorubicin-encapsulating liposomes via a post-insertion procedure (⁶⁴Cu-Dox-immunoliposomes). We evaluated the size and zeta-potential of the liposomes and analyzed target-specific cell binding and cytotoxicity in EGFR-positive cell lines. Then, we analyzed the specific therapeutic effect and PET imaging of the ⁶⁴Cu-Dox-immunoliposomes with the A549 xenograft mouse model. In vivo therapeutic experiments on the mouse models demonstrated that the doxorubicin-containing ⁶⁴Cu-immunoliposomes effectively inhibited tumor growth. Moreover, the ⁶⁴Cu-immunoliposomes provided superior in vivo PET images of the tumors compared to the untargeted liposomes. We suggest that nanoparticles will be the potential platform for cancer treatment as a widely applicable theranostic system.