From Bench to Bedside: Preclinical Studies of Novel Approaches to Cancer Treatment

The focus of this chapter is on the guanidine molecule. Following its synthesis, these molecules have been investigated for various applications. The synthesis of a series of phenyl-guanidines was successfully achieved in high yields through guanylation reactions, utilizing commercially available ZnEt2 as a catalyst. These guanidines were initially evaluated as antitumor agents against various solid tumors, with ACB3 identified as the lead compound of the series. Several biological assays, along with an uptake study of the fluorescent guanidine ACB10 were conducted to elucidate the mechanism of action. The lead compound demonstrated induction of apoptosis, cell cycle arrest, and a reduction in cell adhesion and colony formation, underscoring the potential of the rational design of guanidine-based therapeutic agents for cancer treatment. Following the evaluation of the antitumor properties of this series of phenyl-guanidines, additional potential applications of these compounds were explored. Initially, the guanidine series was used as a scaffold to develop ruthenium metallodrugs for antitumor therapy. A novel family of guanidine-ruthenium derivatives was then synthesized, characterized, and assessed as potential alternatives to platinum-based chemotherapy for cancer treatment. Two lead compounds, RuG3 and RuG8, were identified for their antitumor activity. Further in vitro assays confirmed their strong antiproliferative effects across multiple tumor types, supporting their potential as versatile cancer therapeutic candidates. Furthermore, photophysical studies of the fluorescent ruthenium metallodrug RuG8 revealed an aqueous-induced isomerization process, resulting in the formation of a more symmetrical species, which is proposed as the active form of the complexes. Finally, in vivo evaluation of the RuG3 compound has commenced with preliminary toxicity studies, which demonstrated excellent tolerability, paving the way for ongoing tumor reduction studies. In addition to their role in cancer treatment as antitumor drugs or as versatile scaffolds for developing antitumor metallodrugs, the CS3 guanidine was also investigated as a nanothermometer based on fluorescence lifetime measurements and its bioimaging applications. The study demonstrated that the balance between T-shaped excimers and other aggregated species of CS3 is highly temperature-dependent, with an increase in fluorescence lifetime linked to a greater contribution of T-shaped excimers at the expense of p-p aggregates and monomers. CS3 was further evaluated as a nanothermometer in living cells using MCF7 breast cancer cells, where excellent linearity between lifetime and temperature was also observed, demonstrating exceptional sensitivity. Finally, several of the synthesized guanidines were evaluated for their antimicrobial properties against three distinct strains each of Escherichia coli, of Pseudomonas aeruginosa, and of Staphylococcus aureus, as well as three additional collection and clinical strains of Staphylococcus aureus. Following minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) experiments, and the drop plate (DP) method, guanidine ACB13 was identified as the most active guanidine-based antimicrobial compound, paving the way for the clinical development of these compounds as alternatives for infection treatment. CHAPTER II This chapter explores the potential direct application of different drugs in the treatment of head and neck squamous cell carcinoma (HNSCC). Efforts have been made to enhance the profile of these drugs through the use of nanotechnology. All the nanoparticles discussed in this chapter have received Food and Drug Administration (FDA) approval. Non-conjugated (passive) and antibody-conjugated (active) PLA-polymeric nanoparticles were developed to deliver the PI3K-specific inhibitor Alpelisib in HNSCC tumor cell lines. In vitro results demonstrated that encapsulating Alpelisib in nanoparticles enhances drug efficacy. Furthermore, using DiR fluorophore-labeled antibody-conjugated polymeric nanoparticles (ACPOL-DiR), an improvement in both in vitro drug uptake and in vivo distribution was demonstrated, paving the way for its safe use in HNSCC treatment. Other formulation types were also developed for the treatment of HNSCC. In this case, the drugs Alpelisib and Cisplatin (CDDP) were individually encapsulated in lipid-based nanocarrier drug delivery systems for HNSCC treatment. Passive targeting and active targeting, involving antibody-functionalized liposomes (ACLIP), were again compared. In vitro biological assessments on HNSCC cell lines demonstrated that both passive and active nanomedicines were as effective as the free drugs in reducing cell viability. Additionally, in vivo studies were conducted with DiR-loaded ACLIP. Microscopy and ex vivo imaging revealed an improvement in the accumulation of active targeted liposomes in the tumor compared to passive targeted liposomes.