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Purpose of the study. To study the possibility of detecting freely circulating DNA of the H3F3A (K27M) gene in blood plasma and cerebrospinal fluid in the lumbar spine in children with diffuse midline gliomas (DMG) during a course of radiation therapy (RT).Materials and methods. Molecular genetic studies were carried out by digital PCR. 96 samples of lumbar cerebrospinal fluid and 288 samples of peripheral blood plasma from 96 pediatric patients were analyzed. The concentration of circulating tumor (ctDNA) mutant DNA and wild-type DNA of the H3F3A (K27M) gene was determined in the studied material against the background of a course of RT. Lumbar cerebrospinal fluid sampling was performed once at the beginning of therapy, blood sampling was performed three times: The 1st test before the start of RT, the 2nd against the background of a total dose 10–15 Gy, and the 3rd after the completion of the RT course. Patients are divided into the following groups: patients with stabilization of brain tumor growth during early magnetic resonance (MR) control 3 months after completion of the course of RT; patients with disease progression during the same follow-up period who underwent radiation or chemoradiotherapy.Results. When the disease stabilized after a RT course during treatment, the concentration level of both the mutant variant of ctDNA and wild-type ctDNA significantly decreased in the third blood fraction. The absence of changes or an increase in the concentration of mutant ctDNA and wild-type ctDNA of the H3F3A (K27M) gene by the end of the course of radiation therapy was typical for patients with disease progression in the form of the appearance of metastatic foci in the central nervous system or continued tumor growth. At the same time, the concentration of wild-type DNA of the H3F3A (K27M) gene in the group of patients with progression was higher both in the lumbar cerebrospinal fluid and in the first fraction of blood plasma.Connclusion. Determination of the concentration and dynamics of circulating tumor DNA of the mutant and wild-type of the H3F3A (K27M) gene in blood plasma and lumbar cerebrospinal fluid in children with diffuse median gliomas of the brain during radiation therapy is promising from the point of view of predicting the effectiveness of therapy.

Aim. To evaluate the antitumor efficacy of our developed drug based on cytotoxic T lymphocytes genetically modified with a chimeric antigen receptor (CAR) specific to the CA125 antigen in relation to both CA125-positive and CA125negative cell cultures.Materials and methods. We performed an in vitro study on CA125-positive human ovarian cancer cells (OVCAR-3, OVKATE) and CA125 negative cells (breast cancer MCF 7, embryonic kidney HEK293). Cytotoxic effects on tumor cells were evaluated after 0, 4, 8 and 24 hours using the 3’-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and Lactate Dehydrogenase (LDH) tests. We also studied the changes in the number of cells “in real time” when exposed to transfected lymphocytes using the RTCA iCELLIgence device (ACEA Biosciences, USA). Lymphokineactivated killer (LAK) cells were used as a specificity control.Results. The study demonstrated that anti-CA125 CAR-T lymphocytes exhibited a pronounced cytotoxic effect on OVCAR-3 and OVKATE cell cultures, exceeding the effect of LAK by 1.3 times. The cell population in the experimental samples decreased by 70 ± 4%, which exceeded the LAK effect by 9 ± 8.2%. With regard to the MCF-7 cell line, the cytotoxic effect of anti-CA125 CAR-T lymphocytes was minimal as evidenced by a 25.8% decrease in the relative number of live cells in comparison to the LAK cytotoxicity of 68%. Real-time monitoring of cell proliferation and viability proved a high specific cytotoxic effect of anti-CA125 CAR-T lymphocytes against tumor cultures expressing CA-125, while inferior to LAK in cultures not expressing CA125 (MCF-7, HEK293).Conclusions. The use of anti-CA125 CAR-T lymphocytes against CA125-positive tumor cell lines OVCAR-3 and OVKATE demonstrated a pronounced specific cytotoxic effect exceeding the cytotoxic effect of LAK, which was not achieved against CA125-negative MCF-7 and HEK293 cells.

Introduction. Adoptive immunotherapy based on chimeric antigen receptors (CAR) is considered as a promising direction in the treatment of solid malignant tumors. To produce genetically modified human T-lymphocytes, lenti/retroviral transduction is currently most often used. However, safety concerns associated with the viral vector production and possible unwanted genome modification limit the clinical utility of CAR-T cells. Therefore, non-viral transfection methods, in particular electroporation, using of DNA or RNA vectors, are being actively studied as a method for producing CAR-T lymphocytes.Aim. To evaluate in vivo antitumor activity of the new high-tech drug carplasmin, intended for CAR-T therapy of tumors expressing carcinoembryonic antigen (CEA). Materials and methods. Carplasmin was obtained by electroporation of activated human lymphocytes with plasmid DNA carrying the third generation CAR gene specific to CEA. The study was performed on a human colorectal cancer xenograft model obtained by intraperitoneal injection of CEA-positive HCT116 cell line to athymic Balb/c nude mice. Carplasmin treatment was carried out once a week, starting from the third day after HCT116 cell inoculation. Mice in the two control groups were treated with either electroporated lymphocytes without plasmid addition (pulse-lymphocytes) or RPMI-1640 culture medium (group without treatment).Results. In vivo, carplasmin demonstrated a pronounced antitumor effect. Seven weekly injections of the drug to inoculated mice led to a prominent effect of antitumor therapy: 80 % of the animals in the experimental group survived (with 40 % of the mice had a complete remission without signs of a detectable tumor), compared to 100 % death in the control group (without treatment).Conclusion. The results of preclinical efficacy studies demonstrate that carplasmin is a promising drug for the treatment of CEA-positive intraperitoneal tumors.

Introduction. Currently, there are conflicting data regarding the effect of the c.470T> C germline mutation in the CHEK2 gene on increasing the risk of breast cancer (BC), so it is necessary to conduct research on large samples of patients, including in the Russian population, in order to analyze the contribution of this mutation to the risk of cancer developing.The aim of the study was to determine the frequency of occurrence of the genetic variant c.470Т>С in the CHEK2 gene in the Russian population in patients with BC and patients with benign breast diseases (BBD) to assess the possible effect of this deoxyribonucleic acid damage on the likelihood of cancer occurrence.Materials and methods. The study included 2,787 patients with BC and 1,004 patients with BBD who underwent examination and treatment at the Russian Scientific Center of Roentgenoradiology of the Ministry of the Russian Federation from 2010 to 2018. Molecular genetic study was carried out by real-time polymerase chain reaction to determine the characteristic of the Russian population hereditary genetic variant c.470Т>С in the CHEK2 gene using a diagnostic panel that allows to determine three germline mutations: c.1100delC, c.444+1G>A and c.470Т>С in the CHEK2 gene.Results. In patients with BC the frequency of the mutation c.470T>C in the CHEK2 gene was 3.8 %, in patients with BBD this mutation was detected in 4.7 % of cases. The frequency of the genetic variant c.470T>C in high-risk groups was: 5.1 % – for BC patients with clinical signs of hereditary disease and 4.9 % – for patients with BBD with a family history of cancer. There were no statistically significant differences between the frequency of the mutation c.470T>C in the general groups of BC patients and patients with BBD and the corresponding frequency in the high-risk groups, as well as in the groups of BC patients and patients with BBD (p >0.05).Conclusion. The results of this study indicate the probable absence of a relationship between the presence of the mutation c.470Т>С in the CHEK2 gene and an increased risk of BC.

Background. Application of mathematical modeling for search for biologically active molecules is currently a promising scientific approach. Application of numerical algorithms for optimization of peptide sequences and molecular dynamics allowed to obtain modified peptide sequences that are functional analogs of the sequence of natural inhibitor of cyclin-dependent kinase 4/6 p16INK4a.The study objective is to establish biological characteristics of peptide sequences of CDK 4/6 inhibitors obtained using mathematical modeling.Materials and methods. The studies were performed in vitro using tumor cell lines (MCF-7, А549, SKOV-3, НСТ116). Apoptosis level, cell distribution per cell cycle stages, changes in Bcl-2 expression, changes in the level of phosphorylated pRb under the effect of the studied molecules were investigated using flow cytometry. Proliferation dynamics of cell populations were studied using RTCA iCELLIgence biosensor technology.Results. Peptide sequences obtained using mathematical modeling decrease the level of phosphorylated pRb, Bcl-2 expression when applied to actively proliferating cells. These proteins serve as molecular targets for the cyclin-dependent kinase 4/6–cyclin D complex, and changes in pRb and Bcl-2 levels might indicate inhibition of complex formation. Consequently, decreased proliferative activity and increased apoptosis were observed. Effectiveness of the peptide sequences depended on their molecular structure and type of the used cell line. Two (2) of the studied modified peptide sequences have higher antiproliferative and proapoptotic effect on tumor cells than native p16INK4a (90-97) sequence.Conclusion. Application of mathematical modeling for search and development of functionally active molecules allowed to create peptide sequences with stronger cyclin-dependent kinase inhibitor effect than p16INK4a, the native inhibitor CDK4/6.

Background. The search for molecular markers of colon diseases allowing highly specific and sensitive identification and differentiation of pathological processes is a clinically important problem. Expression levels of genes responsible for proliferation can reflect the changes in the affected tissues. The study objective is to perform comparative analysis of molecular and genetic markers of proliferative activity in benign and malignant neoplasms of the colon. Materials and methods. Analysis of the changes in proliferation markers (CCND1, с-MYC, Ki-67, HER2neu, TERT) in adenocarcinoma of the colon (n = 259), resection margin (about 15–20 cm from the tumor lesion) (n = 251), unchanged colon mucosa from healthy donors (n = 247), polyps (n = 28), unchanged colon mucosa intestinal polyposis (10–15 cm from the polyp) (n = 75) was performed using RT-PCR. Results and conclusion. It was shown that morphologically unchanged tissue of intestinal mucosa in malignant tumors has significant differences from normal tissue of healthy donors. Significant differences in the level of expression of genes responsible for the processes of proliferation, с-MYC, CCND1, TERT were found in benign hyperproliferative diseases (polyps). Moreover, these changes were specific to the type of pathological process, which allows us to consider these genes as the most promising candidates in the development of a differential method for diagnosing colon diseases.

The purpose of systemic treatment in patients with breast cancer is based largely on the molecular characteristics of the primary tumor, but many clinical recommendations suggest also the study of metastatic nodes with an assessment of their receptor status (estrogen receptor ER, progesterone receptor RP, human epidermal growth factor receptor 2 Her2/neu). This is due to the fact that according to numerous studies, the discrepancy between the status of the primary tumor and the secondary nodes can reach high rates: 3–54 % for ER, 5–78 % for RP, and 0–34 % for Her2/neu. At the same time, more and more data actively demonstrate the imperfection of immunohistochemical analysis and the need to study additional parameters to improve the quality of diagnosis of patients with breast cancer. Material and methods. A morphological and immunohistochemical study of the tumor tissue of the primary node and axillary lymph nodes was performed in 199 patients with breast cancer (T1-3N0-3M0) using standard methods, and RT-PCR was also studied with the expression of 24 genes. Results. The incidence of differences between the molecular phenotypes of the main tumor and metastatic axillary lymph nodes was 26 (26 %) of 99 cases. Most often, differences were noted in cases of breast cancer with luminal A type – 13 cases (50 %). According to the results of a comparative PCR analysis of tissue samples from the primary tumor and metastatic regional lymph nodes, only the expression of the CD68, ERSR1, GRB7 and MMD11 receptors was statistically significant. Conclusion. The results indicate the need for an integrated approach and additional methods for the diagnosis of breast cancer, which will undoubtedly improve the quality of planning and the effectiveness of systemic treatment in patients with breast cancer.

Introduction. Adjuvant systemic therapy remains one of the main options for treating breast cancer. Results of standard immunohistochemical studies are not always a criterion for selecting systemic therapy. Nowadays, multigene expression analysis is actively used to predict the response to chemotherapy in patients with earlystage breast cancer. We studied a 24-gene multi-gene panel for typing breast cancer.Material and Methods. A prospective analysis of 199 breast cancer patients (T1–3N0–3M0) was carried out. Surgical specimens were studied using the standard immunohistochemistry (IHC) and RT-PCR for detecting expression of 24 genes.Results. According to the IHC results, breast cancer was divided into 5 molecular subtypes: luminal A was detected in 59 (30 %) patients; luminal B (HER2-negative) in 52 (26 %); luminal B (HER2-positive) in 19 (9 %); triple-negative in 28 (14 %); HER2-positive 41 (21 %). RT-PCR showed that ST K15, MYC, MYBL2, BIRCC 5, BCL2, TERT, ESRP1, PGR, HER2, GBR7, MGB1 and MMP11 were the most significant genes in subtype distribution. The total percentage of matches between the two studies was 61.7 %.Conclusion. Studies have shown the need to add additional typing methods for breast cancer to a standard IHC study, which will undoubtedly increase the information content of diagnostic measures and will improve the effectiveness of the treatment.

Despite the sufficient amount of data accumulated in the literature, there are still no factors, on the basis of which it would be possible to estimate the regional lymph nodes status in breast cancer with a high degree of accuracy. The review presents literature data relating to the influence of clinicopathological, molecular-biological and genetic characteristics of primary tumor on lymph node metastases. Data of 66 foreign and Russian articles are included.