OBJECTIVE:Given the high incidence rate of secondary liver tumors and limitations of the existing treatment options, boiling histotripsy (BH) may provide an incisionless, non-ionizing, ultrasound-guided approach for the mechanical ablation of liver metastases using pulsed high-intensity focused ultrasound waves with shock fronts. This pilot ex vivo study investigated the feasibility of BH for mechanical disintegration of human liver metastases with respect to tumor origin, stiffness, and prior anti-tumor treatment. METHODS:Eighteen human liver metastases were collected via surgical resection or rapid autopsy from anonymized patients aged 39-85 y (median: 68) with confirmed colorectal, gastric, breast, or skin (cutaneous melanoma) cancers, with or without prior targeted therapy or radiation therapy. The Young's moduli of the tumors and adjacent liver tissue were measured using shear wave elastography. BH was then applied to nodes of a volumetric grid (1-4 layers, 3 × 3 - 5 × 5 points per layer, and 1-mm spacing) at 25-200 pulses per point (1-ms pulses and 1% duty cycle) using a 9-ring 2-MHz annular array under real-time ultrasound guidance. Histological analysis of the treatment outcomes was performed with H&E and Masson's trichrome stains; scanning and transmission electron microscopy were employed for ultrastructural analysis of the fragmented tissue. RESULTS:Liver metastases were significantly stiffer than the adjacent liver parenchyma (44 ± 17 kPa vs. 9.3 ± 3.9 kPa; p < 9 × 10-5) regardless of tumor origin; these findings are consistent with clinically relevant Young's modulus values reported in prior in vivo studies. In metastases with spontaneous or prior therapy-induced necrosis, all investigated BH protocols successfully disintegrated the planned volumes; the highest treatment rate of 54 mm3/min was achieved using 75 pulses per point. In metastases with therapy-induced fibrosis, complete disintegration of target volumes was achieved only at 200 pulses per point (treatment rate: 14 mm3/min), whereas lower pulse numbers resulted in the selective fragmentation of non-fibrotic tumor components. Electron microscopy confirmed mechanical disintegration of the tumor tissue down to the subcellular level. CONCLUSION:BH enables non-invasive mechanical ablation of human liver metastases across multiple primary origins. The treatment process can be accelerated by reducing pulse numbers for non-fibrotic or necrotic tumors; however, fibrotic tumors require higher number of BH pulses for complete disintegration. These findings support the use of BH as a potential modality for managing liver metastases, whether applied as a standalone procedure, a neoadjuvant strategy, or following anti-tumor therapy to ensure complete removal of the residual tumor burden.

OBJECTIVE:Leiomyosarcoma (LMS) is a malignant very aggressive tumor, composed of cells exhibiting smooth muscle differentiation, and one of the most common types of soft tissue sarcomas. Here the feasibility of a non-invasive ultrasound-based approach for mechanical fractionation of human LMS, termed boiling histotripsy (BH), was evaluated ex vivo. METHODS:Three autopsy samples of human retroperitoneal LMS were subjected to stiffness measurements via shear wave elastography, followed by a volumetric BH treatment using a custom-made focused ultrasound transducer (1.5 MHz, 12 sectors, F# = 0.75) under diagnostic ultrasound guidance. Volumetric BH lesions (170-230 mm3) were produced in LMS samples through sonication over a 3D grid of foci (2-3 layers of 5 × 5 foci with 1-mm step) with 1 ms or 2 ms pulses delivered 150 or 80 times per focus with 1 % duty cycle (P+/P-/As = 167/-26/179 MPa insitu). BH sonications were performed within 14-20 min and corresponding BH-induced tissue damage was evaluated histologically with H&E staining. RESULTS:Stiffness of autopsy LMS tissue was within the broad range observed clinically. BH treatments were successfully planned and guided with diagnostic ultrasound. Complete liquefaction and cellular disruption of the target tumor volume with sharp boundaries between intact and fractionated tissue was confirmed histologically. CONCLUSION:This pilot study demonstrates the feasibility of boiling histotripsy for non-invasive ultrasound-guided mechanical fractionation of human LMS ex vivo, initiating further extended optimization studies.

Objective: Non-invasive surgical approaches, including boiling histotripsy (BH), are currently being developed for the treatment of brain disorders aiming to avoid craniotomy and exposure of intervening tissues, and, thus, minimize associated complications. This work aimed to demonstrate the feasibility of BH for mechanical fractionation of human brain tissues ex vivo under B-mode guidance, with preliminary measurements of tissue stiffness via shear wave elastography. Methods: Young's moduli of 25 human autopsy brain samples obtained from de-identified patients of 51-91 y old (median 77 y old) were measured via shear wave elastography prior to BH sonication. Seventeen volumetric BH lesions (1-4 layers of 5 x 5 points with a 1- mm step) were produced near brain surface (n = 10), in white matter (n = 3), in thalamus (n = 2), and globus pallidus (n = 2) using 12 element 1.5 MHz sector transducer under B-mode guidance with 10 ms or 2 ms pulses delivered 10 or 15 times per sonication point with 1% duty cycle. After treatment, the lesions were evaluated grossly through bisection, histologically with hematoxylin and eosin staining, and ultrastructurally via scanning and transmission electron microscopy. Results: Young's moduli of autopsy brain samples were lower in older patients (from 32.9 +/- 6.6 kPa in 51 y olds to 10 +/- 2 kPa in 91 y olds) and at higher temperature (6%-50% lower at 37 degrees & Scy; vs 23 degrees & Scy;), and were within the range observed clinically. All tested BH treatments performed near the brain surface (i.e., mostly in gray matter) resulted in formation of well-demarcated rectangular lesions with homogenized content and sharp boundaries, with majority of residual fragments below 100 microns. The use of shorter pulses (2 ms vs 10 ms) accelerated the treatment at least threefold, and the highest liquefaction rate was 568 mm3/min. White matter was more resistant to BH vs gray matter: at least 15 pulses of 2 ms duration were required per each sonication point, and the liquefaction rate was three times lower. The ability of BH to produce lesions in thalamus and globus pallidus was also confirmed. Conclusion: This work presents the first demonstration of BH proof-of-concept in human brain tissues ex vivo under B-mode guidance with clinically relevant treatment rates.

OBJECTIVES:Colorectal cancer (CRC) is the third most common cancer globally and is frequently diagnosed at metastatic stages. As an alternative to the current standard of care, a novel high-intensity-focused ultrasound (HIFU)-based boiling histotripsy (BH) method has the potential to provide an ultrasound (US)-guided approach for non-invasive mechanical fractionation of CRC metastases and enhancement of anti-tumor immune response for inoperable primary CRC. METHODS:Young's modulus of the autopsy human sigmoid colon cancer was first measured using shear wave elastography. Volumetric BH lesion was then produced in the cancer sample ex vivo using a 2-MHz 9-element annular array (67.5° focusing angle) targeting a 3D-grid (5 × 5 foci across 2 transverse layers with 1-mm spacing) under B-mode US guidance. Each focus received 150 pulses of 1-ms duration (peak positive/negative pressures and shock amplitude P+/P/As = 91/-13/78 MPa, acoustic power and initial intensity within the pulse W0 = 125.5 W and I0 = 2.7 W/cm2) delivered at 0.1-s intervals (1% duty cycle). The obtained lesion was analyzed via B-mode imaging and histologically with hematoxylin-eosin and Masson's trichrome. RESULTS:Young's modulus of the autopsy CRC sample was 38 ± 10 kPa and aligned with clinical values for rectal adenocarcinomas. BH treatment was successfully guided in real-time using B-mode US: the treated area was hyperechoic during BH and hypoechoic post-treatment. Histology confirmed the presence of intact mucinous colon carcinoma outside the BH lesion, and fractionated cells and damaged stroma with disrupted collagen fibers within the lesion. CONCLUSIONS:This ex vivo pilot study demonstrates the potential of BH for non-invasive non-thermal US-guided treatment for CRC and metastases.

Colorectal cancer (CRC) is the third most common cancer globally and is frequently diagnosed at metastatic stages. As an alternative to the current standard of care, a novel high‐intensity‐focused ultrasound (HIFU)‐based boiling histotripsy (BH) method has the potential to provide an ultrasound (US)‐guided approach for non‐invasive mechanical fractionation of CRC metastases and enhancement of anti‐tumor immune response for inoperable primary CRC. Young's modulus of the autopsy human sigmoid colon cancer was first measured using shear wave elastography. Volumetric BH lesion was then produced in the cancer sample ex vivo using a 2‐MHz 9‐element annular array (67.5° focusing angle) targeting a 3D‐grid (5 × 5 foci across 2 transverse layers with 1‐mm spacing) under B‐mode US guidance. Each focus received 150 pulses of 1‐ms duration (peak positive/negative pressures and shock amplitude P +/ P/A s = 91/−13/78 MPa, acoustic power and initial intensity within the pulse W 0 = 125.5 W and I 0 = 2.7 W/cm 2 ) delivered at 0.1‐s intervals (1% duty cycle). The obtained lesion was analyzed via B‐mode imaging and histologically with hematoxylin–eosin and Masson's trichrome. Young's modulus of the autopsy CRC sample was 38 ± 10 kPa and aligned with clinical values for rectal adenocarcinomas. BH treatment was successfully guided in real‐time using B‐mode US: the treated area was hyperechoic during BH and hypoechoic post‐treatment. Histology confirmed the presence of intact mucinous colon carcinoma outside the BH lesion, and fractionated cells and damaged stroma with disrupted collagen fibers within the lesion. This ex vivo pilot study demonstrates the potential of BH for non‐invasive non‐thermal US‐guided treatment for CRC and metastases.

Undifferentiated pleomorphic prostate sarcoma is an extremely rare neoplasm. In the available literature, less than 50 clinical cases were described. Usually, the clinical manifestation of the disease is nonspecific and is primarily associated with bladder outlet obstruction. Additionally, most patients have normal levels of prostate-specific antigen, while ultrasound and MRI can visualize irregularly shaped lesions, often extending beyond the prostate gland. Diagnosis requires exclusion of other signs of specific differentiation, apart from fibroblastic and myofibroblastic. There is no established treatment plan for patients with pleomorphic prostate sarcoma due to extreme rarity of the disease. For localized forms of the disease, radical laparoscopic prostatectomy is often used, but more aggressive treatment options are also being considered, including total pelvic exenteration, chemotherapy and radiation therapy. However, in most cases metastasis is revealed after primary treatment. Regional metastases are often localized in the rectum, bladder, in the area of previous surgery, and regional lymph nodes, while distant metastases are found in the lungs, liver, bones and distant lymph nodes, thereby indicating aggressive progression and poor prognosis of the disease.In this article, we present our own clinical observation of a patient with confirmed undifferentiated pleomorphic prostate sarcoma.

OBJECTIVE:A comparative study of detection of breast cancer markers (estrogen receptors, progesterone receptors, HER2/neu, Ki-67) by immunohistochemical method with antibodies produced by PrimeBioMed (Russia) and antibodies produced by Roche Ventana (USA).MATERIAL AND METHODS:Surgical specimens and biopsies from 37 patients with invasive breast cancer were used. Sections were stained with antibodies of clones ER SP1 and GM030, PR 1E2 and PBM-5B8, HER2/neu 4B5 and PBM-46A6, Ki-67 30-9 and GM010.RESULTS:There was a high positive and significant correlation between the immunohistochemistry results and antibodies of the clones ER-SP1 and GM030, PR1E2 and PBM-5B8, HER2/neu4B5 and PBM-46A6, Ki-67 30-9 and GM010.CONCLUSION:The study showed the possibility of using antibodies of clones GM030, HER2/neu 4B5, PBM-46A6, GM010 (PrimeBioMed) on the Ventana Bench Marck Ultra automatic immunostainer using the detection system UltraView Universal DAB Detection Kit.

Today a global problem for humanity is represented by cancer, in particular gastric cancer, which is characterized by high mortality and aggressive course. In this regard, there is a search for new approaches to the diagnosis and therapy of gastric cancer, one of these areas is the study of the expression level of the intercellular adhesion molecule claudin-18.2 in tumor tissue and its use as a target molecule. In the case of various pathological processes, including tumors, the expression profile of claudin-18.2 changes, which indicates its possible role in the initiation and progression of cancer. The aim of this review is to systematize the data on claudin-18.2, its role in normal cell physiology and embryology, as well as in the development of pathological processes in the stomach, its relation to the clinical and morphological characteristics of gastric cancer and importance in biological therapy.

OBJECTIVE:To evaluate the representation and localization of FAP-positive activated stromal cells depending on the severity of fibrotic changes in tissues of patients with a confirmed diagnosis of COVID-19. MATERIAL AND METHODS:20 autopsy observations of patients who died from COVID-19 were studied. Immunohistochemical studies were performed using antibodies to CD90, FAP and aSMA and a dual imaging system. The severity of fibrosis in lung tissue was assessed according to the R.Hubner scale (2008). RESULTS:FAP-positive cells are detected in the lungs, kidneys, liver and myocardium, while only in the lungs FAP expression is associated with fibrotic tissue areas. FAP expression of varying intensity was observed in capillaries, alveolar and bronchial epithelium, as well as in fibrotic nodules in the lungs, where it partially colocalizes with the key myofibroblast marker aSMA. CD90-positive stromal cells were also predominantly found in fibrotic foci. CONCLUSION:The results obtained allow us to clarify the localization of activated stromal precursors in human tissues during injury and suggest an important role of FAP in the formation of fibrotic foci and the progression of fibrotic changes in tissues, primarily the lungs, which makes it a promising pharmaceutical target for the treatment of diseases associated with the development of fibrosis.

We present the results of a pilot study demonstrating the feasibility of non-invasive non-thermal disintegration of human mucinous carcinoma of the breast ex vivo using sequences of high-intensity focused ultrasound pulses in boiling histotripsy regimen. The target volume was sonicated by focusing ultrasound pulses (n=20) of 1.5 MHz frequency, 10-msec duration and 1-sec pulse repetition period, 517 W acoustic power within the pulse, and 103 MPa shock front amplitude at the focus into each node of a volumetric grid 4×4×1 mm. Sonication was visualized and controlled using B-mode ultrasound imaging, total time of the treatment was 21 min. Histological hematoxylin and eosin and Masson’s trichrome staining revealed the absence of tumor elements in the treated region confirming destruction of cancer cells and their nuclei after boiling histotripsy procedure.

OBJECTIVE:As an alternative to surgical excision and magnetic resonance-guided thermal high-intensity focused ultrasound ablation of uterine leiomyoma, this work was aimed at pilot feasibility demonstration of use of ultrasound-guided boiling histotripsy for non-invasive non-thermal fractionation of human uterine leiomyoma ex vivo. METHODS:A custom-made sector ultrasound transducer of 1.5-MHz operating frequency and nominal f-number F# = 0.75 was used to produce a volumetric lesion (two layers of 5 × 5 foci with a 1 mm step) in surgically resected human leiomyoma ex vivo. A sequence of 10 ms pulses (P+/P-/As = 157/-25/170 MPa in situ) with 1% duty cycle was delivered N = 30 times per focus under B-mode guidance. The treatment outcome was evaluated via B-mode imaging and histologically with hematoxylin and eosin and Masson's trichrome staining. RESULTS:The treatment was successfully performed in less than 30 min and resulted in formation of a rectangular lesion visualized on B-mode images during the sonication as an echogenic region, which sustained for about 10 min post-treatment. Histology revealed loss of cellular structure, necrotic debris and globules of degenerated collagen in the target volume surrounded by injured smooth muscle cells. CONCLUSION:The pilot experiment described here indicates that boiling histotripsy is feasible for non-invasive mechanical disintegration of human uterine leiomyoma ex vivo under B-mode guidance, encouraging further investigation and optimization of this potential clinical application of boiling histotripsy.

In 139 patients with verified gastric cancer, the infiltration of the postoperative material with CD8+ cells was analyzed. Automated morphometric analysis of immunostained slides was performed separately in different specimen sites (tumor center, invasive edge, and peritumoral mucosa). The mean area of infiltrating CD8+ cells in the tumor center and in the invasive edge was not predictive, while in the peritumoral mucosa it provided a new negative predictive factor (hazard ratio 2.10; confidence interval 0.87-4.92, Cox regression) reliably associated with the TNM stage (hazard ratio 1.91; confidence interval 0.91-4.61, Cox regression).

Background. The problem of bone defects replacement is relevant nowadays, that is why many scientists create new synthetic bone substitutes, but the ideal material has not been found so far. The aims of the study: 1) to determine the suitability of the monocortical defect model in the rat femur diaphysis with additional prophylactic reinforcement with a bone plate for assessing the biological properties of implanted materials using the commercially available ChronOS material as an example; 2) to assess of the osteoconductive properties of composite materials based on poly(ethylene glycol)diacrylate and octacalcium phosphate with architecture Kelvin and gyroid types on the developed model. Methods. A prospective study, level of evidence II. A monocortical defect of the rat femoral diaphysis (length 7 mm) was produced under anaesthesia in aseptic conditions and fixed with a polyetheretherketone plate and six titanium screws. In the control group, the defect was left empty. In other groups, blocks of one of three materials were implanted сhronOS and composites of poly(ethylene glycol)diacrylate and octacalcium phosphate with 3D-printed Kelvin and gyroid architectures. After 3 and 6 weeks, the rats were sacrificed, and histological examination of the defect zone was performed. The amount of newly formed bone tissue was histometricly assessed, followed by statistical processing of the results. Results. All rats have reached the planned endpoint, and there were no infectious complications or loss of fixation. Histological examination of the defect zone revealed minimal bone growth in the Control group, rather slow bone formation in the Gyroid group, and statistically significantly more pronounced bone formation in the pores of the materials in the Kelvin and Chronos groups. Conclusions. Bone defect in this model was not spontaneously filled with bone tissue and allowed us to study the biological properties of bone substitutes (the ability to biodegrade and osteoconductive properties). The osteoconductive properties of a composite material based on poly(ethylene glycol)diacrylate and octacalcium phosphate with a Kelvin architecture are higher than with a gyroid architecture and are comparable to that of the сhronOS.

Gastric cancer is one of the most common oncological diseases at the present time, so research in this area is very significant and relevant. Immunological checkpoint inhibitors have previously demonstrated their effectiveness and safety in various solid tumors, however, with regard to stomach cancer, to date, ambiguous results have been presented. Tumor cells express programmed death ligand 1 (PD-L1), which binds to its programmed death receptor 1 (PD-1). Immune defense plays a key role in the initiation and progression of the disease. Understanding the regulatory mechanism of PD-L1 in gastric cancer can lead to significant progress in immunotherapy, as well as contribute to the adequate selection of patients treated with checkpoint inhibitors. In the review, we conducted an in-depth study of PD-L1 expression and regulatory immunosuppressive mechanisms in gastric cancer and methods for assessing PD-L1 status, and also studied the results of current clinical trials in which inhibitors of immunological control points were considered in combination with and without chemotherapy for this oncopathology.

To date, pulmonary fibrosis remains an unmet medical need. In this study, we evaluated the potency of mesenchymal stromal cell (MSC) secretome components to prevent pulmonary fibrosis development and facilitate fibrosis resolution. Surprisingly, the intratracheal application of extracellular vesicles (MSC-EVs) or the vesicle-depleted secretome fraction (MSC-SF) was not able to prevent lung fibrosis when applied immediately after the injury caused by bleomycin instillation in mice. However, MSC-EV administration induced the resolution of established pulmonary fibrosis, whereas the vesicle-depleted fraction did not. The application of MSC-EVs caused a decrease in the numbers of myofibroblasts and FAPa + progenitors without affecting their apoptosis. Such a decrease likely occurred due to their dedifferentiation caused by microRNA (miR) transfer by MSC-EVs. Using a murine model of bleomycin-induced pulmonary fibrosis, we confirmed the contribution of specific miRs (miR-29c and miR-129) to the antifibrotic effect of MSC-EVs. Our study provides novel insights into possible antifibrotic therapy based on the use of the vesicle-enriched fraction of the MSC secretome.

OBJECTIVE:Clarification of the prognostic value and relationship of MUC-phenotypes of gastric cancer with clinical and morphological parameters.MATERIAL AND METHODS:Surgical material from 310 patients with a verified diagnosis of gastric cancer was studied. Samples were immunohistochemically stained with antibodies to MUC2, CD10, MUC5AC. The results were compared with clinical and morphological characteristics of gastric cancer and patient survival data.RESULTS:The MUC-null and MUC-mix groups significantly differ in the prevalence of subtotal/total tumors from the MUC-I group (p=0.022 and p=0.007, respectively), where there are significantly fewer such tumors. Tubular tumors were more common in the MUC-null group compared to the MUC-G (p=0.026) and MUC-mix (p=0.006) groups, and there were fewer cases with the presence of "signet-ring" cells in the MUC-null group (p=0.000). When studying the discohesive histological type, the literature data on smaller tumor sizes and a lower frequency of lymph node metastasis for MUC-G status were not confirmed, but a more frequent proximal localization of MUC-I tumors was found (p=0.003). No statistically significant differences in survival were found in the analysis of the total sample. Differences in survival were found only in discohesive cancers, where the best survival was recorded for the MUC-null group, and the worst for the MUC-mix group (p=0.022). MUC status is not an independent predictor of gastric cancer (HR=1.662, p=0.093).CONCLUSION:Between tumors with different MUC statuses, there were differences in localization and belonging to individual histological types. Significant differences in survival were found only for discohesive cancers with MUC-null and MUC-mix statuses. Separation of gastric cancers according to MUC status may have only limited predictive value in selected histological forms of cancer.

Cancer-associated fibroblasts (CAF) are a heterogeneous group of tumor microenvironment cells that are barely studied in metastatic lymph nodes. The presence of CAF in regional metastases of colorectal cancer was assessed by using SMA, PDGFRb, and POD markers; the obtained subpopulations were compared with the primary tumor. A total of 26 cases of colon adenocarcinoma with metastases to regional lymph nodes were studied. Duplex immunohistochemical detection (POD+SMA and PDGFRb+SMA) was carried out by the immunohistochemical method. In most cases, POD was absent in metastases (65.4%) and PDGFRb was present (88.5%). The POD and PDGFRb staining in the invasive edge of the tumor did not correlate with metastasis. Attention was drawn to the absence of POD and PDGFRb reactions in a blood vessel embolus, as well as to negative PDGFRb in metastasis in the presence of pronounced PDGFRb in the primary tumor in patients after neoadjuvant therapy.

BACKGROUND:Currently, PD-L1 expression in patients with tumors of various localizations is being actively studied. Studies on the expression of PD-L1 detected by clones SP142 and SP263 in gastric cancer (for the drugs atezolizumab and durvalumab, respectively) are rare in the literature. The prognostic role of PD-L1 expression in patients who were not treated with immune checkpoint inhibitors has also not been investigated.OBJECTIVE:To determine the expression level of PD-L1 (clones SP263 and SP142, Roche Ventana) in gastric cancer specimens and evaluate its effect on overall survival in patients who did not receive adjuvant therapy with immune checkpoint inhibitors.MATERIAL AND METHODS:The study included 131 patients with a verified diagnosis of gastric cancer. The material obtained from 127 patients was stained with antibodies to PD-L1 SP263, and from 126 patients - with antibodies to PD-L1 SP142. A multivariate Cox regression model with Wald's step-by-step exclusion algorithm was used to evaluate predictors of survival.RESULTS:The total five-year survival rate of patients in the PD-L1-negative tumor group was significantly lower than the total five-year survival rate of patients in the PD-L1-positive tumor group, which was 50.0% and 40.0% also for both clones (p=0.027). An increase in the expression of PD-L1 clone SP263, determined by both the CPS and TPS method, reduces the chances of death by 1.35 times (p=0.02) and 1.61 times (p=0.004), respectively. An increase in the expression of PD-L1 clone SP142, determined by the CPS method, reduces the chances of death by 1.54 times (p=0.005).CONCLUSION:The survival rate of patients in the group of PD-L1-positive tumors is significantly higher than in patients in the group of PD-L1-negative tumors. Elevated PD-L1 expression, as assessed by the SP263 and SP142 clones, is an important prognostic marker that predicts a higher chance of overall survival for patients, even though these patients are not receiving immune checkpoint inhibitors adjuvant therapy.

Immunotherapy of malignant tumors is a rapidly developing area of oncology. PD-1 is a receptor expressed by activated T-lymphocytes. As a result of its interaction with the ligand (PD-L1 or PD-L2), the activity of T-lymphocytes is inhibited and their apoptosis occurs. Drugs that inhibit the interaction of PD-1 with ligands have an immunostimulatory effect and are effective in the treatment of many types of neoplasms: melanoma, lung cancer, bladder cancer, stomach cancer, various lymphomas, etc. However, response to this treatment is observed only in a narrow cohort of patients. To increase the effectiveness of immunotherapy, combined preparations and nanoparticles are being developed and created to enhance the effect of PD-L1 inhibitors, and containing hyaluronic acid as a ligand for the CD44 protein, which is expressed in many human tumors. However, the issue of co-expression of CD44 and PD-L1 remains poorly understood. This review is devoted to describing the features of co-expression and the mechanisms of interaction between CD44 and PD-L1. Promising directions for the development of new approaches to the immunotherapy of malignant tumors are presented.

Cancer-associated fibroblasts (CAFs) — mesenchymal cells in the tumor stroma, play one of the leading roles in tumor progression in many different tumors, including colorectal cancer. Scientists have described many markers for CAFs, but none of them is specific. We performed immunohistochemistry tests using five antibodies (αSMA, POD, FAP, PDGFRα, PDGFRβ) to investigate CAFs in three zones of 49 colorectal adenocarcinomas: apical, central, and invasive edge. We revealed the reliable correlation between high PDGFRβ and PDGFRα value in the apical zone and deeper invasion (T3–T4) ( p = 0.0281 and p = 0.0137). High αSMA level in apical zone ( p = 0.0001), αSMA level in central zone ( p = 0.019), POD level in apical zone ( p = 0.0222), POD level in central zone ( p = 0.0206) and PDGFRβ level in apical zone ( p = 0.014) correlated reliably with the presence of metastasis in lymphatic nodules. For the first time, focused on the inner layer of CAF adjacent to tumor complexes. We observed that cases with inner αSMA expression were significantly more often ( p = 0.023) characterized by the presence of regional lymph node metastasis compared with cases with mix of CAF markers ( p = 0.007) and with cases with inner POD expression ( p = 0.024). The found relationships between the level of markers and the presence of metastases indicate their clinical significance.