Vol 51, No 2 (2025)

The development of medicines, the structure of which resembles or is completely identical to the natural components of a living organism, is currently a promising and of great interest among scientists. The invention of a synthetic analog of nucleic acids was carried out due to the active development of oligonucleotide synthesis in the 1980s and subsequent research in the field of chemical modification of the nucleotide, which made it possible to change the properties of nucleic acids and increase their stability. The accumulated world experience has made it possible to create medicines based on synthetic oligonucleotides aimed at the treatment of rare genetic diseases. Since 1998, a relatively small number of drugs have been approved by regulatory authorities in different countries for use in clinical practice. Most of them are aimed at the treatment of orphan diseases. To date, there are 20 therapeutic drugs based on synthetic oligonucleotides that have been approved by medical regulatory authorities for use in clinical practice. Of this list, only one drug was developed in Russia (MIR 19^®). This review describes all drugs based on synthetic oligonucleotides approved for 2024, and also examines and systematizes current knowledge about promising types of therapeutic oligonucleotides with different mechanisms of interaction with the target.

Today, cancer continues to be one of the most dangerous diseases, annually causing the deaths of >9 million people in the world. Therefore, new and more effective methods of cancer therapy are in demand. Monoclonal antibody-based immunotherapy has already shown its effectiveness; and antibody-drug conjugates (ADC), as one of its successful variants, have significant and not yet fully realized potential. ADCs are monoclonal antibodies bound by linkers to cytotoxic drugs. In many clinical trials and already in standard clinical practice ADCs have demonstrated significant advantages over combination therapy with unmodified antibodies and chemotherapy drugs. Due to new achievements in the field of molecular immunology and biotechnology, the potential of ADCs is assessed as a breakthrough, which will allow them to become the most sought-after anticancer drugs in the coming years. Owing to ADC, it has become possible to deliver drugs to tumor cells in a targeted manner without significant toxic effects on healthy tissues and organs. To date, 15 ADC drugs have been approved worldwide for use in clinic, and more than a hundred more drugs of this class are at various stages of clinical trials. At the same time, therapy using ADC is associated with certain side effects and limited efficacy, and therefore there is a need to develop more advanced conjugates. This review examines the history of the development of ADC as a therapeutic class of drugs, their structure, targets and mechanism of action. It also outlines the prospects and directions for further development of ADCs.

A method for the synthesis of aTf1 and aTf2 nanobodies conjugates, previously obtained for human holo- and apo-transferrin (Tf) with fluorescein isothiocyanate (FITC), is proposed. The conjugates were used as tracers for the fluorescence polarization immunoassay (FPIA) method with nanobodies. Optimal concentrations of FITC-aTf1 and FITC-aTf2 conjugates (2.5–5 nM) were selected. Binding kinetics of FITC-aTf1 and FITC-aTf2 with holo- and apo-Tf was studied. A complete binding of FITC-aTf1 and FITC-aTf2 conjugates with holo- and apo-Tf was observed after 15 and 5 min of incubation, respectively. The equilibrium dissociation constants of FITC-aTf1*holo-Tf and FITC-aTf2*apo-Tf complexes were determined, which amounted to 30.7 ± 0.3 and 15.3 ± 0.2 nM. A high specificity of analysis was verified by the incubation of FITC-aTf1 and FITC-aTf2 conjugates with other human proteins, lactoferrin, serum albumin, lysozyme. A high affinity of the conjugates FITC-aTf1 and FITC-aTf2 to holo- and apo-Tf was also shown. The synthesized FITC-aTf1 and FITC-aTf2 conjugates have potential for determining transferrin various conformations in human physiological fluids. Thus, this work demonstrates the possibility of determining two forms of transferrin in human physiological fluids using the FPIA method, which may have diagnostic value, and the use of a portable fluorescence analyzer will allow this analysis to be carried out outside the walls of specialized laboratories.

A new genetically encoded fluorescent tag picoFAST has been proposed, which contains only 88 amino acids and is currently the smallest fluorogen-activating protein. It was shown that the picoFAST protein in complex with HBR-DOM2 fluorogen can be used as a genetically encoded fluorescent label for staining individual structures of living cells.

This work presents a new version of synthetic analogues of oligonucleotides containing two types of modifications – phosphoryl guanidine (PG) internucleotide group and 2ʹ,4ʹ-locked ribose fragments (LNA) – in one nucleotide unit. It has been shown the presence of PG-LNA linkages decreases the electrophoretic mobility of the oligonucleotides, primarily due to the electroneutrality of the PG group. Additionally, the PG-LNA modifications increase the hydrophobicity of the oligonucleotides, resulting in longer retention times during reversed-phase chromatography. The thermal stability of complementary duplexes containing PG-LNA oligonucleotides has been investigated. It was found the melting temperature increases by 1.5–4.0°C per modification, depending on the position of the modified unit and the ionic strength of the solution. Furthermore, circular dichroism spectropolarimetry revealed the secondary structure of the complexes formed by PG-LNA differs from the B-form, which may be attributed to the presence of LNA fragments exhibiting a 3'-endo conformation of the ribose ring. Thus, PG-LNA oligonucleotides can be considered as a new structural analogue of RNA with partially uncharged backbone. Based on the data obtained, it can be concluded that PG-LNA oligonucleotides can be considered as a promising tool for various methods of isolation and analysis of nucleic acids.

Pore-forming toxin hemolysin II (HlyII) secreted by the gram-positive bacterium Bacillus cereus is one of the main pathogenic factors of this microorganism. The action of HlyII leads to cell lysis due to pore formation on membranes. Monoclonal antibodies against the large C-terminal fragment (Met225–Ile412, HlyIILCTD) of HlyII B. cereus were obtained using hybridoma technology with the use of a recombinant soluble form of HlyIILCTD as an antigen, which was obtained using the chaperone protein SlyD. Monoclonal antibody LCTD-83 inhibited the hemolytic activity of HlyII, the degree of protection depended on the presence/absence of proline at position 324 in the primary sequence of the toxin. The antibody most effectively inhibited erythrocyte hemolysis caused by HlyII B-771, in the sequence of which Pro is present at position 324 instead of Leu. It was shown that the LCTD-83 antibody interacts with the formed pores on the erythrocyte membranes, thereby blocking the possible release of intracellular contents. HlyII and its mutant forms were obtained using recombinant producer strains of Escherichia coli BL21 (DE3). The ability of antibodies to recognize antigens was characterized by enzyme-linked immunosorbent assay (ELISA) and immunoblotting; immunoprecipitation was used to demonstrate interaction with the membrane pores formed by the toxin. LCTD-83 interacted less effectively with the full-length toxin than with HlyIILCTD, which confirmed the fact that pore formation is accompanied by a change in the toxin conformation. In this regard, antibodies interacting with its oligomeric form are promising for suppressing the cytolytic effect of hemolysin II. LCTD-83 has the potential to identify ways to neutralize the toxin.

Platinum polyoxometalates are Pt (IV) complexes containing bulky cluster ligands. We have shown previously that platinum polyoxoniobate [(Nb₆O₁₉)₂{Pt(OH)₂}₂]¹²⁻ (Pt-PON1) containing two Pt centers can covalently bind DNA. Here we have addressed the structural stability of Pt-PON1 and its conjugate with guanine at the N7 position, cytotoxicity of this compound, and its accumulation in living cells. Quantum mechanical modeling showed that the Pt-PON1 complex is unstable outside the crystal lattice, while its conjugate with guanine likely undergoes structural rearrangement quite easily. A decrease in the survival of Escherichia coli XL1-Blue and DH5α strains and human HEK293T and MCF-7 cell lines was observed already at 20 μM Pt-PON1 but at higher concentrations the compound was poorly soluble in biologically compatible media. Atomic emission spectroscopy for Pt and Nb showed that Pt-PON1 is efficiently taken up by human cells in a stoichiometry corresponding to the original complex. Thus, platinum polyoxometalates, provided their solubility can be improved, may be considered as promising antitumor agents.