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

Prostate cancer is the second most common type of cancer among men. Its main method of treatment is chemotherapy, which has a wide range of side effects. One of the solutions to this challenge is targeted delivery to prostate cancer cells. Here we synthesized a novel small-molecule PSMA-targeted conjugate based on the monomethyl auristatin E. Its structure and conformational properties were investigated by NMR spectroscopy. Cytotoxicity, intracellular reactive oxygen species induction, and stability under liver microsomes and P450-cytochrome species were investigated for this conjugate. The conjugate demonstrated 77-85% tumor growth inhibition levels on 22Rv1 (PSMA (+)) xenografts, compared with a 37% inhibition level on PC-3 (PSMA (-)) xenografts, in a single dose of 0.3 mg/kg and a sufficiently high therapeutic index of 21. Acute, chronic, and subchronic toxicities and pharmacokinetics have shown that the synthesized conjugate is a promising potential agent for the chemotherapy of prostate cancer.

Preclinical Study of Biofunctional Polymer-Coated Upconversion Nanoparticles.

Upconversion nanoparticles (UCNPs) are new-generation photoluminescent nanomaterials gaining considerable recognition in the life sciences due to their unique optical properties that allow high-contrast imaging in cells and tissues. Upconversion nanoparticle applications in optical diagnosis, bioassays, therapeutics, photodynamic therapy, drug delivery, and light-controlled release of drugs are promising, demanding a comprehensive systematic study of their pharmacological properties. We report on production of biofunctional UCNP-based nanocomplexes suitable for optical microscopy and imaging of HER2-positive cells and tumors, as well as on the comprehensive evaluation of their pharmacokinetics, pharmacodynamics, and toxicological properties using cells and laboratory animals. The nanocomplexes represent a UCNP core/shell structure of the NaYF4:Yb, Er, Tm/NaYF4 composition coated with an amphiphilic alternating copolymer of maleic anhydride with 1-octadecene (PMAO) and conjugated to the Designed Ankyrin Repeat Protein (DARPin 9_29) with high affinity to the HER2 receptor. We demonstrated the specific binding of UCNP-PMAO-DARPin to HER2-positive cancer cells in cultures and xenograft animal models allowing the tumor visualization for at least 24 h. An exhaustive study of the general and specific toxicity of UCNP-PMAO-DARPin including the evaluation of their allergenic, immunotoxic, and reprotoxic properties was carried out. The obtained experimental body of evidence leads to a conclusion that UCNP-PMAO and UCNP-PMAO-DARPin are functional, noncytotoxic, biocompatible, and safe for imaging applications in cells, small animals, and prospective clinical applications of image-guided surgery.