Synthesis and Biological Evaluation of PSMA Ligands with Aromatic Residues and Fluorescent Conjugates Based on Them

Abstract

Prostate-specific membrane antigen (PSMA), also known as glutamate carboxypeptidase II (GCPII), is a suitable target for specific delivery of antitumor drugs and diagnostic agents due to its overexpression in prostate cancer cells. In the current work, we describe the design, synthesis, and biological evaluation of novel low-molecular PSMA ligands and conjugates with fluorescent dyes FAM-5, SulfoCy5, and SulfoCy7. In vitro evaluation of synthesized PSMA ligands on the activity of PSMA shows that the addition of aromatic amino acids into a linker structure leads to a significant increase in inhibition. The conjugates of the most potent ligand with FAM-5 as well as SulfoCy5 demonstrated high affinities to PSMA-expressing tumor cells in vitro. In vivo biodistribution in 22Rv1 xenografts in Balb/c nude mice of PSMA-SulfoCy5 and PSMA-SulfoCy7 conjugates with a novel PSMA ligand demonstrated good visualization of PSMA-expressing tumors. Also, the conjugate PSMA-SulfoCy7 demonstrated the absence of any explicit toxicity up to 87.9 mg/kg.

Synthesis, Characterization, and Preclinical Evaluation of a Small-Molecule Prostate-Specific Membrane Antigen-Targeted Monomethyl Auristatin E Conjugate

“…41 In vitro tests inhibiting cleavage of the N-acetyl-Laspartyl-L-glutamate reaction demonstrated that the DCL ureabased ligand containing an m-chloro-substituted aromatic moiety at a lysine atom and a dipeptide linker (L-phenylalanine-L-tyrosine) had the best IC 50 value (9 ± 3 nM) compared with 2-PMPA, which had an IC 50 value of 80 ± 24 nM. 34,42 The synthesis scheme proposes a separate synthesis and the modification of the urea vector with a dipeptide linker based on phenylalanine and tyrosine. The use of a Val-Cit-PAB cathepsin-cleavable linker for the binding and delivery of monomethyl auristatin E has been done in practice.…”

“…We previously worked to modify low-molecular-weight PSMA ligands with a linker to increase their affinity for PSMA ,…”

“…This ligand had successfully demonstrated itself with the fluorescent dyes SulfoCy5 and SulfoCy7 in both in vitro and in vivo experiments. 34 It is especially worth noting that both the synthesis and the final conjugate presented were patented (WO 2021101407 A1). 35…”

“…In this work, we implemented a synthetic approach to a conjugate based on monomethyl auristatin E, where a previously optimized ligand with a high affinity to PSMA was used as the target molecule. This ligand had successfully demonstrated itself with the fluorescent dyes SulfoCy5 and SulfoCy7 in both in vitro and in vivo experiments . It is especially worth noting that both the synthesis and the final conjugate presented were patented (WO 2021101407 A1)…”

Synthesis and initial in vitro evaluation of PSMA-targeted ligands with optimized structural motifs.

“…[4 -6] By introducing substituents of different nature into their structure, high-a nity rates can be achieved (Figure 1A). This study was an extension of the previously developed series of PSMA ligands (a complete table of ligands including the previously developed library is given in the supplementary data) (Table S2) [7,8] A series of 14 ligands was obtained based on the methodologies we developed and optimized earlier. The detailed synthetic scheme of these ligands is given in the Supplementary data.…”