# Steering the Clinical Translation of Delivery Systems for Drugs and Health Products
## 3 Poster Presentations
### Mannose-Targeted Cationic Glycopolymers as New Tool for pDNA-Based Cancer Immunotherapy  
[PERSON] 1, [PERSON] 2, [PERSON] 1, [PERSON] 1, [PERSON] 1, [PERSON] 2 and [PERSON] 1,*  
1 Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Via F. Marzolo 5, 35131 Padua, Italy  
2 Faculty of Pharmacy, University of Helsinki, Viikinkaari 5E, 00790 Helsinki, Finland  
* Correspondence: [EMAIL_ADDRESS]  
Tumor immunology is changing the landscape of modern anticancer therapy and the delivery of pDNA encoding Tumor Associated Antigens (TAAs) is emerging as a new strategy for anticancer vaccination. In this scenario, synthetic polymeric carriers have recently drawn increasing attention. In this work, Reversible Addition Fragmentation chain Transfer (RAFT) polymerization has been exploited for the synthesis of a small library of copolymers designed to deliver pDNA encoding TAAs to antigen presenting cells (APCs) and to trigger the immune response and memory against cancer. These polymers were designed such that Agm initiates nucleic acid electrostatic interactions and triggers formation of polyplexes that are stabilized by the presence in the outer layer of a mannosylated corona, thought to shield the polyplex charges in the core via steric hindrance mechanism, to confer stealth properties to the polyplex and, most importantly, to actively target mannose receptor (MR) expressed on APCs. Eventually, a hydrophobic butyl acrylate-based block (But) was introduced to provoke membrane disruption tuned to promote endosomal escape. Importantly, the system is also expected to provide nucleic acid protection against fast degradation, minimizing its interactions with nucleases.  
Diblock Man58-b-Agm45 and a triblock Man62-b-Agm52-b-But32 cationic copolymers were generated by fast RAFT polymerization starting from D-Mannose acrylamide (Man) and Agmatine acrylamide (Agm), monomers and, for the triblock, performing the final chain extension with butyl acrylate (But). Polymers were found to fully complex model pDNA encoding for Enhanced Green Fluorescence Protein(pEGFP) at N/P ratios lower than 5 with the resulting glycoplexes (GPPs) being stable in the presence of physiological concentration of heparin. Furthermore, DLS and TEM characterization confirmed the co-existence of toroid-, rod- and spherical-shaped GPPswith a size distribution in the range of 100-1000 nm. In vitro flow cytometric studies revealed a remarkably high transfection of DC2.4 immortalized dendritic cells for Man58-b-Agm45/pEGFP and Man62-b-Agm52-b-But32/pEGFP, although the addition of the butyl-based block on the latter decreased the selectivity for MR-expressing cells, as shown by preliminary assays performed on model Chinese hamster Ovary cells (wild type CHO or mannose receptor expressing CHO-MR+). Finally, GPPs formulated with ovalbumin-encoding plasmid (pOVA) were found to efficiently stimulate the expression on DCs of the costimulatory clusters of differentiation CD86 and the presentation of the SIINFEKL ovalbumin antigenic epitope by MHC I molecule, with Man62-b-Agm52-b-But32/pOVA performing better than Man58-b-Agm45/pOVA. Despite that, therapeutic in vivo mice vaccination experiments highlighted Man58-b-Agm45/pOVA as the most promising candidate for cancer vaccine development, since it was able to control the tumor growth, and to efficiently induce the priming and the T cells specific activation against SIINFEKL antigenic peptide.  
Future Perspectives: ongoing studies will investigate polymers suitability for mRNA complexation and delivery, thus enabling their exploitability for cell transfection and anticancer vaccination with a wide range of genetic therapeutics.  
**Acknowledgments:** We acknowledge the University of Padua for financial support through the \"STARS Starting Grants (STARS-StG)\" (Grant No. MAST_STARS18_02; CUP G91I18001190005;) and the \"Progetto di Ricerca di Dipartimento Junior--PRID-J\" (Grant No MAST_SID2017_01; CUP C93C17002300005).