During this first year, the project focused on building a library of supramolecules and related building blocks for further structural characterization. In particular, different types of metallacages of the type M2L4 (M = Pd2+, Pt2+, L = ditopic N-donor ligand) were synthesized and fully characterized. We devoted significant time to design cage scaffolds exo-functionalized with different moieties for tethering to bioactive ligands, including synthons for radiolabeling, fluorophores and peptides. The conditions for the radiolabeling were optimized for the free ligands and ongoing studies are focused on the obtainment of the respective cage structures. Preliminary studies were conducted to study the host-guest chemistry of the new metallacages.
For rotaxane-based molecules, we focused on synthesizing monomeric building blocks to create a flexible and modular rotaxane platform. Preliminary test reactions were conducted to demonstrate the concept of rotaxane self-assembly. However, further synthetic refinement is required to optimize rotaxane synthesis and expand the library of monomeric compounds with diverse functional units in the coming months. Finally, we developed N-heterocyclic carbene (NHC) ligands as stabilizers of gold nanoparticles. In particular, water soluble NHCs were synthesized based on the imidazole and benzimidazole scaffolds. Further, the synthesis of the NHC@AuNPs was attempted using two different bottom-up approaches. Significant time was devoted to developing a methodology yielding stable, non-aggregated and small-sized uniform particles.
To prepare for the biological evaluation of our agents, a high-throughput screening platform was developed to conduct saturation binding assays with radioligands in vitro. Access to resected medulloblastoma tissue was further granted through the UMCU/PMC biobank. Here, target expression was determined through gold-standard immunohistochemistry and independently scored by pathology. In addition, the chicken chorioallantoic membrane (CAM) model was optimized to grow multiple NSCLC xenograft tumors. We will use this model as the primary in vivo screen for our novel agents. Importantly, we have performed technology transfer of these techniques from KCL to UMCU to use the CAM model for growth and in ovo analysis of medulloblastoma. To date, the model has been successfully implemented, and the growth of three patient-derived organoids has been achieved. Moreover, we have developed and optimised the growth of orthotopic, PDX, and GEMM in vivo models of NSCLC.
It is important to compare our novel supramolecular radiotheranostics with gold-standard agents using conventional covalent chemistry. We have made progress towards developing antibody-based ‘conventional’ radiotheranostics that target both EGFR and xCT.
