A Proof-of-Concept Study on the Theranostic Potential of ¹⁷⁷ Lu-labeled Biocompatible Covalent Polymer Nanoparticles...

Theranostic nanomedicine combined bioimaging and therapy probably rises more helpful and interesting opportunities for personalized medicine. In this work, ¹⁷⁷ Lu radiolabeling and surface PEGylation of biocompatible covalent polymer nanoparticles (CPNs) have generated a new theranostic nanoformulation (¹⁷⁷ Lu-DOTA-PEG-CPNs) for targeted diagnosis and treatment of breast cancer. The in vitro anticancer investigations demonstrate that ¹⁷⁷ Lu-DOTA-PEG-CPNs possess excellent bonding capacity with breast cancer cells (4T1), inhibiting the cell viability, leading to cell apoptosis, arresting the cell cycle, and upregulating the reactive oxygen species (ROS), which can be attributed to the good targeting ability of the nanocarrier and the strong relative biological effect of the radionuclide labelled compound. Single photon emission computed tomography/ computed tomography (SPECT/CT) imaging and in vivo biodistribution based on ¹⁷⁷ Lu-DOTA-PEG-CPNs reveal that notable radioactivity accumulation at tumor site in murine 4T1 models with both intravenous and intratumoral administration of the prepared radiotracer. Significant tumor inhibition has been observed in mice treated with ¹⁷⁷ Lu-DOTA-PEG-CPNs, of which the median survival was highly extended. More strikingly, 50 % of mice intratumorally injected with ¹⁷⁷ Lu-DOTA-PEG-CPNs was cured and showed no tumor recurrence within 90 days. The outcome of this work can provide new hints for traditional nanomedicines and promote clinical translation of ¹⁷⁷ Lu radiolabeled compounds efficiently.