Strategic Optimization of Nanoparticle Characteristics to Enhance Tumor Targeting and Doxorubicin Delivery

Young-Jin Lee, Jisan Hong, Bo-Yeon Seo, Byung-Heon Lee, Vijaya Sarangthem,* Rang-Woon Park* Department of Biochemistry and Cell Biology, Cell & Matrix Research Institute, Kyungpook National University, School of Medicine, Daegu, 41944, Republic of Korea*These authors contributed equally to this workCorrespondence: Rang-Woon Park, Email [email protected] Vijaya Sarangthem, Email [email protected]: Doxorubicin (Dox) is a potent anticancer agent; however, its therapeutic efficacy is constrained by a narrow therapeutic index, resulting in nonselective cardiotoxicity and nephrotoxicity. To improve its specificity and therapeutic efficacy, multivalent targeting strategies are being developed.Methods: A chimeric polypeptide consisting of an elastin-like polypeptides (ELP) copolymer with a repeating IL-4 receptor-specific targeting peptide, AP-1, and a (GGCGSCGSC)2 sequence encoding 6 cysteine residues (C6) at the carboxyl-terminus for Dox conjugation was designed. Several AP1-ELPs of varying molecular sizes and structures, ranging from unimers to micelle-forming polymers, were characterized to evaluate their influence on Dox delivery and tumor inhibition.Results: Conjugating Dox to the C6 via an acid-labile linker induced self-assembly into micelle-like structures at body temperature. The size of these multivalent constructs significantly influenced their tumor penetration and overall therapeutic outcomes. High molecular weight, micelle-forming AP1-ELP constructs demonstrated faster tumor entry and enhanced inhibition compared to lower molecular weight linear AP1-ELPs. Tumor uptake of Dox was five times greater than that of free drug and twice that of low molecular weight, linear AP1-ELPs. Furthermore, systemic administration of these high molecular weight constructs effectively inhibited tumor growth in breast carcinoma xenograft models without inducing specific organ toxicity.Conclusion: Outperforming free Dox, high molecular weight micelle-forming AP1-ELP constructs achieve superior tumor targeting and efficacy with minimal toxicity, highlighting their potential as safer and more promising carriers for targeted drug delivery. Keywords: doxorubicin, tumor-targeting, elastin-like polypeptide, multivalent targeting, IL-4 receptor, AP1-ELPs, size dependency, tumor penetration, therapeutic efficacy, AP1-ELP-Dox