Let g be a classical simple Lie algebra over an algebraically closed field F of characteristic zero or large enough, and let n be a maximal nilpotent subalgebra of g. The main tool in representation theory of n is the orbit method, which classifies primitive ideals in the universal enveloping algebra U(n) and unitary representations of the unipotent group N=exp(n) in terms of coadjoint orbits on the dual space n∗. In the paper, we describe explicitly coadjoint orbits of low dimension for n as above. The answer is given in terms of subsets of positive roots. As a corollary, we provide a way to calculate the number of irreducible complex representations of dimensions q, q2 and q3 for a maximal unipotent subgroup N(q) in a classical Chevalley group G(q) over a finite field Fq with q elements. It turned out that this number is a polynomial in q−1 with nonnegative integer coefficients, which agrees with Isaac’s conjecture.

CAR-T cell therapy is a type of adoptive immune therapy that relies on the specific targeting of cytotoxic T-cells to eliminate the malfunctioning cells in the body. Genetic engineering allows the generation of an almost infinite variety of chimeric antigen receptors (CAR) to ensure specificity for antigens on the surface of target cells. Therefore, CAR-T appears to be a powerful and versatile therapy for the treatment of various diseases, including cancer. Recently, CAR-T has emerged as a significant advancement in the management of hematological tumors, particularly B-cell malignancies, mainly due to the presence of specific antigens such as CD19 and BCMA. As a result, the market for CAR-T therapy is experiencing significant growth. However, the problem of relapses remains and warrants the search for new therapeutic approaches, including CAR-T technology. In this case, one of the major challenges is finding and evaluating new targets for CAR-T in terms of their likelihood of success. Here we propose a set of established criteria for the evaluation of potential targets for CAR-T cell therapy to treat hematological malignancies. These criteria include assessing the target in terms of its biological characteristics, such as expression level, cellular localization, tissue specificity, and clinical aspects, including unmet clinical needs and the success of clinical trials. Using these criteria, we validate our prediction of the next CAR-T cell therapy targets that will likely emerge soon.

Neuroblastoma (NB) is an embryonic malignancy causing 15 % of pediatric cancer fatalities. Amplification of the MYCN gene is one of the major NB drivers and biomarkers of high-risk NB. MYCN amplification is associated with high p53-coding gene expression and decreased survival rates in patients. Importantly, only 1-2 % of NB cases harbor TP53 mutations. Moreover, both high TP53 and low MYC expression levels are unfavorable prognostic markers for NB patients, which is not typical for most types of tumors. In this study we analyzed the effect of MYCN amplification on the expression of genes coding p53 family members - TP63 and TP73. We show that, unlike TP53, TP63 and TP73 levels are higher in MYCN-amplified samples. Furthermore, high TP63 and TP73 expression is a favorable prognostic marker for NB patients' survival. That MDM2 inhibition contributes to p53 stabilization and augments the cytotoxic activity of doxorubicin in NB cells prompted us to test the cytotoxic effects of three small-molecule inhibitors of MDM2 that differ in their mechanisms: Nutlin-3a, Mel23, and SP-141. Our results showed that despite the same target, MDM2, these compounds displayed different cytotoxic effects and synergy with doxorubicin on two widely used NB cell lines, IMR-32 and SH-SY5Y that vary in the amount of MDM2 expression. Collectively, our results suggest that except Nutlin-3a, the other two inhibitors, Mel23 and SP-141, employ additional Mdm2-independent mechanisms of cytotoxicity in NB cells that warrants further investigation.

Background: Colorectal cancer is the third most commonly diagnosed cancer and the second leading cause of cancer-related death. Immunotherapy for colorectal cancer is a relatively new area of effective treatment. A special place in immunotherapy is occupied by CAR-T, the targets for which can be NKG2D ligands. These molecules are widely found on various types of tumors and stressed cells. These include MICA, MICB, and ULBPs, which we tested for expression in human colorectal cell lines HT-29, RKO, LOVO, HCT116. These lines were also tested for resistance to FOLFOX, cytokines, and NKG2D-CAR-T itself. Materials and methods: Ligand expression was tested by flow cytometry and qPCR. MTT assay was used to test FOLFOX sensitivity. Cytokine and CAR-T cell death assay was tested by RTCA (real-time cytotoxicity assay). Results: The colorectal cancer cell lines tested displayed a heterogeneous pattern of NKG2D ligand expression, with distinct differences in their sensitivity to treatment. Among the panel, the RKO line emerged as the most resistant to the chemotherapeutic regimen FOLFOX, showing only limited loss of viability under drug exposure. In contrast, HT-29 and LOVO cells responded markedly to cytokine stimulation, indicating a higher degree of vulnerability to immune-mediated cytotoxic signals. RKO cells, however, exhibited relative insensitivity to cytokines, reinforcing their resistant phenotype. Importantly, when challenged with NKG2D-based CAR-T cells, all colorectal cancer lines tested—including RKO—were efficiently recognized and lysed. None of the lines displayed measurable resistance to NKG2D-CAR-T activity, underscoring the broad potential of this approach to overcome intrinsic heterogeneity in cytokine and chemotherapy responses. Conclusion: Our NKG2D-CAR-Ts demonstrate versatility against human colorectal cell lines and lack of resistance to them even in cancer types that are potentially resistant to chemotherapy or cytokine therapy. Acknowledgement: This work was supported by the grant AP19677062 from the Ministry of Education and Science of RK “Employment of NKG2D as chimeric receptor of immune cells and chemokines CXCL9/10 for enhancement of therapeutic effect on colorectal cancer cells“ References: Schmiedel, D., Mandelboim, O. NKG2D ligands–critical targets for cancer immune escape and therapy. Front. Immunol. 9, 2040 (2018). Key words: NKG2D ligands, CAR-T cells, colorectal cancer, immunotherapy, cytokine sensitivity

Neutron-activated Si-31 is an almost pure beta emitter and is one of the short-lived radionuclides, including beta-gamma emitter Mn-56, which were created in a form of residual radioactivity in the early period after the atomic bombing of Hiroshima and Nagasaki. The features of the biological effects of internal irradiation by these radionuclides are a subject of scientific discussions and research. The publication presents data on internal radiation doses in experimental Wistar rats that were exposed to sprayed neutron-activated microparticles of (SiO2)-Si-31. Doses of internal radiation could be conditionally divided into three groups according to their values. It has been found that elevated values of internal radiation doses in rats' organs/tissues as a result of exposure to sprayed (SiO2)-Si-31 microparticles with initial activity of 3.2 x 10(7) Bq varied from 10 to 120 mGy (eyes, lungs, skin, stomach, jejunum, large intestine). The moderate dose values were in the range from 1.9 to 3.7 mGy (trachea, esophagus, ileum). The smallest doses were received by the kidney, testis, blood, cerebellum, heart, liver, cerebrum, bladder, spleen and thymus (from 0.11 to 0.94 mGy). The obtained data are important for interpreting the results of ongoing and planned biological experiments with (SiO2)-Si-31 microparticles-in comparison with the previously published data on features of biological effects caused by beta-gamma emitting (MnO2)-Mn-56 neutron-activated microparticles.

The use of chimeric antigen receptor (CAR)-T cells has enhanced the range of available therapeutic modalities in the context of cancer treatment. CAR-T cells have demonstrated considerable efficacy in the targeted eradication of blood cancer cells, thereby stimulating substantial interest in the advancement of such therapeutic approaches. However, the efficacy of CAR-T cells against solid tumor cells has been limited due to the presence of various obstacles. Solid tumors exhibit antigenic diversity and an immunosuppressive microenvironment, which presents a challenge for immune cells attempting to penetrate the tumor. CAR-T cells also demonstrate decreased proliferative activity and cytotoxicity. Furthermore, concerns exist regarding tumor antigen loss and therapy-associated toxicity. Currently, scientists are working to enhance the structure of the CAR and improve the survival and efficiency of CAR-T cells in recognizing tumor antigens in solid tumors. Chemotherapy drugs are frequently employed in the treatment of malignant neoplasms and can also be used prior to cell therapy to enhance CAR-T cell engraftment. Recent studies have demonstrated that chemotherapy drugs can mitigate the suppressive impact of TME, eliminate the physical barrier by destroying the tumor stroma, and facilitate greater penetration of immune cells and CAR-T cells into the tumor. This, in turn, increases their survival, persistence, and cytotoxicity, as well as affects the metabolism of immune cells inside the tumor. However, the effectiveness of the combined approach against solid tumors depends on several factors, including the type of tumor, dosage, population of CAR-T cells, and individual characteristics of the body. This review examines the principal obstacles to the utilization of CAR-T cells against solid tumors, proposes solutions to these issues, and assesses the potential advantages of a combined approach to radiation exposure, which has the potential to enhance the sensitivity of the tumor to other agents.

Background. Research in oncology assumes establishment and usage of xenograft animal models, meeting the requirements of humanity and rationality. Although praised as promising field of research, preclinical studies of low-molecular-weight inhibitors, antitumor monoclonal antibodies, vaccines, cellular therapy products, CAR-T cells entail continuous control of tumor growth dynamics. Luciferase detection of bioluminescence requires injection of a reporter substrate. However, injections not only are laborious, time-consuming and expensive, but are also stressful for animals. Thus, a vast variety of new visualization methods is employed, including proteins of the far-red spectrum. Objective. The study aimed to compare detection efficiency of tumor growth dynamics in mice models of cervical cancer, applying a commercially available line of fluorescent red protein derivatives of Katushka clade and Renilla luciferase, that is commonly used in in vivo studies . Design and methods. Xenograft mice models were derived injecting modified HeLa cell line, that expresses fluorescent reporter proteins: Katushka, Katushka2S, TurboRFP, TurboFP650 and Renilla enzyme. Results. Spectral properties and emission wavelength of far-red fluorescent protein Katushka and Katushka2S outlines these markers within RFP derivatives lineage as outstanding instrument for in vivo tumor visualization. Conclusion. Detection of fluorescent far-red reporters Katushka and Katushka2S can be considered as a credible alternative to Renilla luciferase bioluminescence in experimental models in vivo on the part of immunotherapy research.

Aim. To generate anti-PD-L1 CAR-T effectors carrying extracellular domain PD-1 as antigen-recognizing site and to study their cytolytic activity as well as to functionally assess the anti-PD-L1 CAR-T effectors in vitro with a view to apply them in multi-targeted tumor therapy. Materials & Methods. Chimeric antigen receptor PD-1 was constructed using molecular cloning of PD-1 antigen-recognizing region (12–170 amino acids) into mammalian expression plasmid vector adding activation and co-stimulatory domains. Primary Т-lymphocytes of healthy donor peripheral blood mononuclear fraction were derived by expanding monoclonal antibody combination on surface markers CD3/CD28. Anti-PD-L1 CAR-T effectors were obtained by lentiviral transduction of primary T-lymphocyte genome of a healthy donor. Chimeric antigen receptor PD-1 expression and transduction efficiency were assessed by flow cytofluorometry. Specific cytotoxicity of the anti-PD-L1 CAR-T effectors was analyzed in vitro by means of real-time cytotoxicity assay (RTCA) with HeLa_PD-L1 target cell line co-cultivation. The level of cytokines IL-2, IL-4, IL-6, IL-10, TNF-α, IFN-γ, and IL-17A was assessed by flow cytofluorometry using Human Th1/Th2/Th17 CBA Kit (BD, USA). Results. The efficiency of lentiviral transduction and the proportion of the anti-PD-L1 CAR-T effectors were 42 %. The specificity of cytotoxic response of the anti-PD-L1 CAR-T effectors with a low effector/tumor ratio (1:20) was verified during HeLa_PD-L1 co-cultivation by a 1.5-fold decrease in the cell index (CI = 0.738) versus control (CI = 1.0645). The increase in synthesis of cytokines IL-2 (1000 pg/mL), IL-6 (438.5 pg/mL), TNF-α (44 pg/mL), and IFN-γ (1034 pg/mL) during HeLa_PD-L1 target cell line co-cultivation confirms the functionality of the analyzed effector cells. Conclusion. Anti-PD-L1 chimeric antigen receptor was constructed and tested in vitro. Anti-PD-L1 CAR-T lymphocytes specifically recognize and promote the cytolysis of tumor target cells by increased secretion of pro-inflammatory cytokines IFN-γ, TNF-α, IL-6, and IL-2. Chimeric antigen receptor PD-1 can be modified into chimeric switch receptor (CSR) by deleting CD3ζ-domain and can be used together with other CARs without predicted non-specific toxicity.

The most often diagnosed and fatal malignancy in women is breast cancer. The International Agency for Research on Cancer (IARC) estimates that there are 2.26 million new cases of cancer in 2020. Adoptive cell therapy using T cells with chimeric antigen receptor shows potential for the treatment of solid tumors, such as breast cancer. In this work the effectiveness of CAR-T cells against monolayer and three-dimensional bioprinted tumor-like structures made of modified MCF-7 breast cancer cells was assessed. The cytokine profile of supernatants after co-cultivation of MCF-7 tumor cell models with CAR-T cells was also measured to reveal the inflammatory background associated with this interaction.

The protein-specific methyltransferase Set7/9 is known for its ability to add methyl groups to lysine residues on many targets, including as histones H1.4, H2A, H2B, H3, and non-histone proteins such as p53, NFκB, E2F1, pRb, Hif1α, β-catenin, STAT3, and YY1 transcription factors. Set7/9 affects both the landscape of histone modifications and the functionality of the aforementioned TFs, and acts as an essential mediator of vital cellular functions, regulating tumor growth and the neoplastic transformation of normal cells. The number of studies demonstrating the determining role of Set7/9 in cancer is growing. Importantly, the effect of Set7/9 on tumor progression is ambivalent and cancer-type dependent. In this study we analyzed the potential participation of Set7/9 in the essential cellular processes in breast cancer cells and revealed that Set7/9 may be involved in DNA damage signaling and DNA repair processes. We further demonstrated that Set7/9 expression is downregulated in cancerous breast tissues and inversely correlated to PARP1 expression level. Using breast cancer cell lines of HER2-positive and triple negative subtypes we have shown that the attenuation of Set7/9 led to the stabilization of PARP1 on both mRNA and protein levels that in turn resulted in cisplatin resistance acquiring. Finally, we demonstrated that the combination of cisplatin with FDA approved PARP1 inhibitor niraparib (Zejula) has a synergistic effect with cisplatin and thereby allows to overcome cisplatin resistance of Set7/9 deficient breast cancer cells.

Aim. To assess the rate of DNMT3A, IDH1, IDH2, and ASXL1 gene mutations and their effect on the prognosis both as isolated findings and in combination with well-known chromosomal aberrations and gene mutations in newly diagnosed acute myeloid leukemia (AML) patients from some regions of the Russian Federation. Materials & Methods. The study enrolled 83 patients with newly diagnosed AML from 22 regions of the Russian Federation, who underwent molecular genetic examination for detecting IDH1 (R132), IDH2 (R140), ASXL1, and DNMT3A gene mutations with droplet digital PCR and Sanger sequencing methods. Results. The mutation rate in DNMT3A was 16.7 %, in IDH1 (R132) it was 6 %, in IDH2 (R140) it was 9.6 %, and in ASXL1 it was 6 %. The R140 mutation in IDH2 correlated with the older age of patients. The mutations in IDH1 (R132), IDH2 (R140), and DNMT3A showed a significant association with mutated NPM1. The mutations in IDH1 (R132), IDH2 (R140) were reported to occur significantly more often in patients with normal karyotype. The IDH1 (R132) and IDH2 (R140) mutations appeared to have a favorable effect on AML prognosis, which is most likely to be associated with a high rate of their compatibility with NPM1 mutation. The mutated type of DNMT3A had a negative effect on overall survival of patients with NPM1 mutation. The mutation in ASXL1 also appeared to be an unfavorable prognostic factor for overall survival of patients with wild type NPM1. Conclusion. A high rate of mutation occurrence in epigenetic regulation genes as well as the prognostic potential of these mutations in AML necessitate the need for determining the mutation status of DNMT3A, IDH1, IDH2, and ASXL1 in the context of primary diagnosis in real-world clinical practice.

In recent years, adoptive cell therapy has gained a new perspective of application due to the development of technologies and the successful clinical use of CAR-T cells for the treatment of patients with malignant B-cell neoplasms. However, the efficacy of CAR-T therapy against solid tumor remains a major scientific and clinical challenge. In this work, we evaluated the cytotoxicity of 2nd generation CAR-T cells against modified solid tumors cell lines-lung adenocarcinoma cell line H522, prostate carcinoma PC-3M, breast carcinoma MDA-MB-231, and epidermoid carcinoma A431 cell lines transduced with lentiviruses encoding red fluorescent protein Katushka2S and the CD19 antigen. A correlation was demonstrated between an increase in the secretion of proinflammatory cytokines and a decrease in the confluence of tumor cells' monolayer. The proposed approach can potentially be applied to preliminarily assess CAR-T cell efficacy for the treatment of solid tumors and estimate the risks of developing cytokine release syndrome.

Acute myeloid leukemias (AML) are the most ubiquitous of all adult leukemias. The prognosis of the disease depends on its genetic profile. The mutation in FLT3 gene, which codes FMS-like tyrosine kinase 3, is observed in 1/3 of patients and is responsible for a high rate of relapses. The prognosis of relapsed/refractory FLT3-positive AML is extremely poor. The standard intensive therapy rarely yields long-term responses. The new first- and second-generation FLT3 tyrosine kinase inhibitors enriched treatment opportunities for patients with this mutation. Gilteritinib, a potent second-generation FLT3-ITD/TKD inhibitor, is a new effective and well tolerated drug for the treatment of relapsed/refractory FLT3-positive AML. Due to its efficacy, low toxicity, and good manageability, this drug can be administered to all patients, including the elderly or those with severe comorbidities and complications of previous therapy. Besides, this drug can be used in outpatient units. The present paper contains three case reports dealing with different clinical situations in patients with FLT3-positive AML treated with gilteritinib in real-world clinical practice.

INTRODUCTION. The main risk to the clinical translatability of preclinical results for anticancer medicinal products is posed by the difficulty of simulating clinical conditions in an experimental model. With only 5% of product candidates proving clinically effective, the search for new approaches to the preclinical development of anticancer medicinal products is currently an active area of research in medicine.AIM. This study aimed to provide methodological support for planning experiments with modelling of neoplastic processes through analysis and classification of the methods used in preclinical studies of the efficacy of anticancer medicinal products in vivo.DISCUSSION. This article reviews the development of animal tumour models and the selection of cell lines and their testing for tumourigenicity and viability on a step-by-step basis. According to the study results, imaging systems, vital staining, and fluorescence- and luminescence-based methods can be used to assess the efficacy of anticancer medicinal products in both solid tumour models and haematological malignancy models. The article presents a schematic representation of the main types of mouse cancer models. However, no single animal species is universally suitable for in vivo cancer modelling. Researchers selecting models and considering their advantages and disadvantages should pay special attention to the similarity of disease mechanisms in animal models and humans at the tissue and molecular level, keeping in mind the aims of their research.CONCLUSIONS. The results of this comparative analysis of methods for preclinical efficacy evaluation of anticancer medicinal products are essential for designing experimental studies and ensuring the reliability of the results obtained. Choosing the correct research method will increase the chances of obtaining experimental data that can be successfully translated into clinical practice.

Aim. To study antitumor cytotoxic effect of CAR-T NKG2D and CAR-T anti-CD19 in vitro and in vivo in order to compare antitumor activity of chimeric antigen receptors (CAR) with different structural and functional properties. Materials & Methods. CAR constructions were produced by molecular cloning. CAR-T cell populations were obtained by transduction of healthy donor T-lymphocytes with recombinant lentiviral particles coding CAR NKG2D or CD19 target antigen CAR sequences. CAR-T cell proportion was assessed by FusionRed fluorescence and EGFR membrane receptor imaging. Specific in vitro cytotoxic activity of CAR-T effector cells was analyzed by Real-Time Cytotoxicity Assay (RTCA) during co-cultivation with HeLa_CD19 target cell line using xCELLigence. Interferon-Y (IFN-y) synthesis in vitro and in vivo along with the degree of cytotoxic effect were analyzed by immunoassay of culture medium of co-cultivated effector cells and target cells as well as isolated auto-plasma from the peripheral blood of mice. To assess the in vivo functional activity, CAR-T cell populations were infused into immunodeficient NSG-SGM3 mice (10 000 000 cells/mouse) 12 days after HeLa_CD19 cell injection and confirmation of engraftment and tumor growth. Upon euthanasia, tumors were removed and fixed in paraffin to prepare histological sections. CAR-T cell tumor infiltration was assessed by CD3 antigen immunohistochemical staining. Results. The highest ligand (molecules MICA, ULBP1/2/3/4/5/6) expression levels were detected in HeLa cell line. The obtained NKG2D CAR-T cells showed a considerable cytotoxic activity against HeLa_CD19 target line (cell index [CI] = 1.27), which was, however, twice as low as that of CAR-T anti-CD19 (CI = 0.60) (p = 0.0038). IFN-y level during co-cultivation of CAR-T anti-CD19 with HeLa_CD19 at the ratio of Е/Т = 1:1 was 64,852 pcg/mL, which was 3.5 times higher than IFN-y level during co-cultivation of CAR-T NKG2D with HeLa_CD19 (18,635 pcg/mL) (p = 0.0360). The degree of tumor infiltration by CAR-T anti-CD19 cells was higher than that by CAR-T NKG2D. The absence of NKG2D proliferating CAR-T cells in mice peripheral blood confirms their low persistence. IFN-y concentration in mice auto-plasma was 11.89 pcg/mL after CAR-T anti-CD19 infusion and 0.57 pcg/mL after CAR-T NKG2D infusion (p = 0.0079). The mean weight of tumor xenografts in experimental groups 10 days after CAR-T anti-CD19 injection was 0.72 g (p = 0.0142), after Т-lymphocyte and NKG2D CAR-T cell infusions it was 2.12 g and 1.2 g, respectively. Conclusion. CAR-T anti-CD19 cells are characterized by more pronounced cytotoxic effect under both in vitro and in vivo experimental conditions compared with CAR-T NKG2D cells. The degree of CAR-T anti-CD19 proliferation and their infiltration in mice xenograft models is considerably higher than the levels reached with NKG2D CAR-T cell injections. A single CAR-T NKG2D injection results only in short-term tumor reduction.

Immunotherapy using chimeric antigen receptor (CAR) T cells is a promising option for cancer treatment. However, T cells and CAR-T cells frequently become dysfunctional in cancer, where numerous evasion mechanisms impair antitumor immunity. Cancer frequently exploits intrinsic T cell dysfunction mechanisms that evolved for the purpose of defending against autoimmunity. T cell exhaustion is the most studied type of T cell dysfunction. It is characterized by impaired proliferation and cytokine secretion and is often misdefined solely by the expression of the inhibitory receptors. Another type of dysfunction is T cell senescence, which occurs when T cells permanently arrest their cell cycle and proliferation while retaining cytotoxic capability. The first section of this review provides a broad overview of T cell dysfunctional states, including exhaustion and senescence; the second section is focused on the impact of T cell dysfunction on the CAR-T therapeutic potential. Finally, we discuss the recent efforts to mitigate CAR-T cell exhaustion, with an emphasis on epigenetic and transcriptional modulation.

Medulloblastoma is one of the most common pediatric central nervous system malignancies worldwide, and it is characterized by frequent leptomeningeal metastasizing. We report a rare case of primary leptomeningeal medulloblastoma of an 11-year-old Caucasian girl with a long-term disease history, non-specific clinical course, and challenges in the diagnosis verification. To date, 4 cases of pediatric primary leptomeningeal medulloblastoma are reported, and all of them are associated with unfavorable outcomes. The approaches of neuroimaging and diagnosis verification are analyzed in the article to provide opportunities for effective diagnosis of this disease in clinical practice. The reported clinical case of the primary leptomeningeal medulloblastoma is characterized by MR images with non-specific changes in the brain and spinal cord and by 18FDG-PET/CT images with diffuse heterogeneous hyperfixation of the radiopharmaceutical along the whole spinal cord. The immunohistochemistry and next-generation sequencing analyses of tumor samples were performed for comprehensive characterization of the reported clinical case.