Biodistributionof ⁸⁹Zr-Radiolabeled Nanoassembliesfor Monoclonal Antibody Delivery Revealed through <i>In Vivo</i> PET Imaging

Despite the outstanding performance of monoclonal antibodies (mAbs) in the clinic, their full potential has been hindered due to their inability to cross cell membranes and therefore reach intracellular targets. The use of nanotechnology to deliver mAbs to intracellular domains has been highlighted as a strategy with high potential. Working toward this goal, we have recently developed and validated palmitoyl hyaluronate (HAC16)-based nanoassemblies (HANAs), a novel technology for the intracellular delivery of mAbs in Kirsten Rat Sarcoma Virus (KRAS)-mutated tumors, one of the most prevalent and a challenging intracellular oncoprotein. Despite their success, the pharmacokinetics and biodistribution of these delivery vehicles are still unknown due to their chemical complexity, a challenge common to a large proportion of drug delivery nanomedicines. To support further development and clinical translation, we present an efficient radiolabeling approach with the positron emitter zirconium-89 (⁸⁹Zr) for the <i>in vivo</i> evaluation of HANAs by whole-body PET imaging. Additionally, we assessed the impact of PEGylation and size modulation on the biodistribution profile of mAbs using ⁸⁹Zr-radiolabeled PEGylated and non-PEGylated HANAs. Our PET imaging results demonstrated that HANAs significantly modify the pharmacokinetics and biodistribution of the ⁸⁹Zr-mAb. Furthermore, we established that the biodistribution of HANAs can be conveniently modulated by introducing PEG polymers on the surface, facilitating customization for cancer applications. This versatile radiolabeling strategy provides a facile approach for the <i>in vivo</i> evaluation of complex nanoformulations loaded with mAbs, in a quantitative manner with high sensitivity.