Current State of Immunotherapy and Mechanisms of Immune Evasion in Ewing Sarcoma and Osteosarcoma

Decoding the immune landscape in Ewing sarcoma pathogenesis: The role of tumor infiltrating immune cells and immune milieu

Ewing sarcoma (EwS) is the second most prevalent pediatric bone malignancy, characterized by its aggressive behavior and unfavorable prognosis. The tumor microenvironment (TME) of EwS is shaped by immunosuppressive components, including myeloid-derived suppressor cells, tumor-associated macrophages, and immune checkpoint molecules such as PD-1/PD-L1 and HLA-G. These elements impair anti-tumor immune responses by modulating the function of tumor-infiltrating immune cells, such as regulatory T cells (Tregs), CD8+ T cells, and natural killer cells. Chemokines, including CXCL9 and CXCL12, and cytokines, such as transforming growth factor-beta and interleukin-10, further contribute to immune suppression and promote metastatic dissemination. Recent advances in immunotherapy have highlighted the therapeutic potential of modulating immune cells and signaling pathways to enhance anti-tumor immunity. This review provides a comprehensive analysis of the complex immune landscape within the EwS TME, focusing on the mechanistic roles of key immune components and their potential as therapeutic targets. Understanding these interactions could pave the way for innovative treatment strategies to improve clinical outcomes in patients with EwS.

Targeting friend leukemia integration 1: A promising approach for prevention and treatment of solid tumors

Friend leukemia integration 1 (FLI1) is an ETS transcription factor first identified in erythroleukemia. This protein contributes to various cellular functions such as cell growth and proliferation, apoptosis, angiogenesis, etc. FLI1 is also known to be involved in tumorigenesis. The role of this transcription factor as a proto-oncogene, promoting cancer progression, especially Ewing sarcoma, is well reported. Recent research has found the connection of FLI1 with other solid cancers, including breast cancer, prostate cancer, glioma, and lung cancer. The role of this protein in solid cancers is also controversial. FLI1 is found to promote and suppress cancer growth and progression, particularly in Ewing sarcoma and breast cancer. This review article aims to provide a detailed perception of the FLI1-associated mechanisms in various solid cancers for preventive and therapeutic implications. The result of bioinformatic analysis using the cBioportal database (https://www.cbioportal.org/) is also presented in this article to understand the effect of this protein on solid cancers. Moreover, the current status of FLI1 targeting agents for preventing and treating solid cancers has been focused. Several studies established the efficacy of FLI1 inhibitors in solid tumor therapy. A few reports are also available on the effect of FLI1 agonists on solid tumors. This article discussed different FLI1 targeting agents to provide insight into the FLI1 targeting mechanisms required for discovering more potent FLI1 targeting agents and better therapeutic outcomes.

Targeted inactivation of EWSR1 : : FLI1 gene in Ewing sarcoma via CRISPR/Cas9 driven by an Ewing-specific GGAA promoter

We have recently demonstrated that genetic inactivation of EWSR1 : : FLI1 by CRISPR/Cas9, successfully blocks cell proliferation in a cell model of Ewing sarcoma. However, CRISPR/Cas9-mediated gene editing can exhibit off-target effects, and thus, precise regulation of Cas9 expression in target cells is essential to develop gene-editing strategies to inactivate EWSR1 : : FLI1 in Ewing sarcoma cells. In this study, we demonstrate that Cas9 can be specifically expressed in Ewing sarcoma cells when located downstream a promoter consisting of GGAA repeats and a consensus TATA box (GGAAprom). Under these conditions, Cas9 is selectively expressed in Ewing sarcoma cells that express EWSR1 : : FLI1 oncoproteins, but not in cells expressing wild-type FLI1. Consequently, Ewing sarcoma cells infected with GGAAprom>Cas9 and a specific gRNA designed to inactivate EWSR1 : : FLI1, showed successful EWSR1 : : FLI1 inactivation and the subsequent blockade of cell proliferation. Notably, GGAAprom>Cas9 can be efficiently delivered to Ewing sarcoma cells via adenoviral vectors both in vitro and in vivo, highlighting the potential of this approach for Ewing sarcoma treatment. Our results demonstrate that the CRISPR/Cas9 machinery is safe and specific for Ewing sarcoma cells when driven under a GGAAprom, paving the way for the development of cancer gene therapies based on the selective expression of genes with therapeutic potential.

Clinical characterization and therapeutic targeting of fusion genes in oncology

Gene fusions represent important oncogenic driver mutations resulting in aberrant cellular signaling. In up to 17% of all solid tumors at least one gene fusion can be identified. Precision therapy targeting fusion gene signaling has demonstrated effective clinical benefit. Advancements in clinically relevant next-generation sequencing and bioinformatic techniques have enabled expansion of therapeutic opportunity to subpopulations of patients with fusion gene expression. Clinically, tyrosine inhibitors have shown efficacy in treating fusion gene expressing cancers. Fusion genes are also clonal mutations, meaning it is a personal cancer target involving all cancer cells of that patient, not just a subpopulation of cancer cells within the cancer mass. Thus, both fusion signal disruption and immune signal targeting are effective therapeutic directions. This review discusses fusion gene targeting, therapeutic resistance, and molecular biomarkers.

Integrated analysis reveals an immune evasion prognostic signature for predicting the overall survival in patients with hepatocellular carcinoma

BACKGROUND

The development of immunotherapy has enriched the treatment of hepatocellular carcinoma (HCC), but the efficacy is not as expected, which may be due to immune evasion. Immune evasion is related to the immune microenvironment of HCC, but there is little research on it.

METHODS

We employed unsupervised clustering analysis to categorize patients from TCGA based on 182 immune evasion-related genes (IEGs). We utilized single-sample gene set enrichment analysis (ssGSEA) and CIBERSORT to calculate differences in immune cell infiltration between clusters. The differences in immune cells and immune-related pathways were assessed using GSEA. We constructed an immune escape prognosis signature (IEPS) using univariate Cox and LASSO Cox algorithms and evaluated the predictive performance of IEPS with receiver operating characteristic (ROC) curves and survival curves. Additionally, we established a nomogram for clinical application based on IEPS. IHC validated the expression of Carbamoyl phosphate synthetase 2, Aspartate transcarbamylase, and Dihydroorotase (CAD) and Phosphatidylinositol Glycan Anchor Biosynthesis Class U (PIGU) in HCC. We transfected liver cancer cell lines with siRNA and overexpression plasmids, and confirmed the relationship between CAD, PIGU, and the potential downstream TGF-β1 in HCC using qRT-PCR and Western blot. Finally, we validated the tumor response of CAD overexpression using an animal model.

RESULTS

Unsupervised clustering analysis based on IEGs divided HCC patients from TCGA into two groups. There were significant differences in prognosis and immune characteristics between the two groups of patients. Scoring of TCGA patients using IEPS revealed that higher scores were associated with poorer overall survival (OS). Validation was performed using the ICGC database. TIME analysis indicated that patients in the high-IEPS group were in an immunosuppressive state, possibly due to a significant increase in Treg infiltration. Compared to normal liver cells, HCC cells expressed higher levels of CAD and PIGU. Cellular experimental results showed a positive correlation between CAD, PIGU and the potential downstream TGF-β1 expression. Animal experiments demonstrated that CAD significantly promoted tumor progression, with an increase in Treg infiltration.

CONCLUSION

IEPS has strong prognostic value for HCC patients, and CAD and PIGU provide perspectives on new biomarkers and therapeutic targets for HCC.

Characterization of a novel sarcoma cell line with an EWSR1::POU2AF3 fusion

Sarcomas with an EWSR1::POU2AF3(COLCA2) fusion are a very recently described entity of preferentially sinonasal origin and with undifferentiated round/spindle cell morphology. We established a novel cell line (PF1095) carrying a EWSR1::POU2AF3 fusion from the malignant pleural effusion of a 25-year-old sarcoma patient. The patient was first diagnosed with poorly differentiated neuroendocrine carcinoma based on tumor cell morphology and positivity to markers such as EMA, synaptophysin, and CD56. Later, the EWSR1 translocation was identified in the tumor cells with unknown partners and the patient received chemotherapy according to the Ewing 2008 protocol in combination with surgery and proton beam radiotherapy. At the time of cell line establishment, the disease progressed to pleural sarcomatosis with pleural effusion. In the cell line, we identified POU2AF3 as a fusion partner of EWSR1 and a TP53 frameshift deletion. Next, we determined the sensitivity of PF1095 cells to the currently approved chemotherapies in comparison to two conventional Ewing sarcoma lines (EW-7 and MHH-ES1) with the two most frequent EWSR::FLI1 fusions. Finally, we tested potential new combination therapies. We performed cell viability, proliferation, and cell cycle assays. We found that the proliferation rate of PF1095 cells was much slower than the EWSR1::FLI1 fusion lines and they also had a lower sensitivity to both irinotecan and doxorubicin treatment. Expression level of SLFN11, a predictor of sensitivity to DNA damaging agents, was also lower in PF1095 cells. Combination treatment with the PARP inhibitors olaparib and irinotecan or doxorubicin synergistically reduced cell viability and induced cell death and cell cycle arrest. This unique cell model provides an opportunity to test therapeutic approaches preclinically for this novel and aggressive sarcoma entity.

A detoxified TLR4 agonist inhibits tumour growth and lung metastasis of osteosarcoma by promoting CD8+ cytotoxic lymphocyte infiltration

BACKGROUND

Osteosarcoma is the most common malignant bone tumour with limited treatment options and poor outcomes in advanced metastatic cases. Current immunotherapies show limited efficacy, highlighting the need for novel therapeutic approaches. Systemic immune activation by Toll-like receptor 4 (TLR4) immunostimulants has shown great promise; however, current TLR4 agonists' toxicity hinders this systemic approach in patients with osteosarcoma.

METHODS

We compared the antitumour effect of lipopolysaccharides (LPS) with that of an innovative chemically detoxified TLR4 agonist (Lipo-MP-LPS) in a syngeneic metastatic osteosarcoma mouse model. Lipo-MP-LPS exhibited an optimal safety and solubility profile for systemic administration at an effective dose. We evaluated tumour growth, lung metastases, and immune cell infiltration in wild-type and TLR4-mutant mice and performed selective immunodepletion.

RESULTS

Lipo-MP-LPS exhibited antitumour effects against localised osteosarcoma tumours and lung metastases, like those of natural LPS. Lipo-MP-LPS promoted CD8+ T cells and M1 macrophages infiltration in primary tumours and CD8+ T cells in metastases, with an M1-phenotype macrophage shift. The Lipo-MP-LPS antitumour effects were found to depend on TLR4 and CD8+ T cells, but not on macrophages.

CONCLUSION

Lipo-MP-LPS inhibited tumour growth and lung metastasis of osteosarcoma by promoting CD8 + T cell infiltration, indicating its therapeutic potential for advanced osteosarcoma.

Exploring viral mimicry combined with epigenetics and tumor immunity: new perspectives in cancer therapy

Viral mimicry refers to an active antiviral response triggered by the activation of endogenous retroviruses (ERVs), usually manifested by the formation of double-stranded RNA (dsRNA) and activation of the cellular interferon response, which activates the immune system and produces anti-tumor effects. Epigenetic studies have shown that epigenetic modifications (e.g. DNA methylation, histone modifications, etc.) play a crucial role in tumorigenesis, progression, and treatment resistance. Particularly, alterations in DNA methylation may be closely associated with the suppression of ERVs expression, and treatment by demethylation may restore ERVs activity and thus strengthen the tumor immune response. Therefore, we propose that viral mimicry can induce immune responses in the tumor microenvironment by activating the expression of ERVs, and that epigenetic alterations may play a key regulatory role in this process. In this paper, we review the intersection of viral mimicry, epigenetics and tumor immunotherapy, and explore the possible interactions and synergistic effects among the three, aiming to provide a new theoretical basis and potential strategies for cancer immunotherapy.

Cytokine screening identifies TNF to potentially enhance immunogenicity of pediatric sarcomas

Introduction

Pediatric sarcomas, including osteosarcoma (OS), Ewing sarcoma (EwS) and rhabdomyosarcoma (RMS) carry low somatic mutational burden and low MHC-I expression, posing a challenge for T cell therapies. Our previous study showed that mediators of monocyte maturation sensitized the EwS cell line A673 to lysis by HLA-A*02:01/CHM1319-specific allorestricted T cell receptor (TCR) transgenic CD8+ T cells (CHM1319 CD8+ T cells).

Methods

In this study, we tested a panel of monocyte maturation cytokines for their ability to upregulate immunogenic cell surface markers on OS, EwS and RMS cell lines, using flow cytometry. xCELLigence, SRB and ELISpot assays were used to assess whether TNF pretreatment increases CD8+ T cell cytotoxicity.

Results

We observed that TNF and IL-1β upregulated MHC class I, ICAM-1 as well as CD83 and PD-L1 on the surface of pediatric sarcoma cell lines, while IL-4, GM-CSF, IL-6 and PGE2 failed to induce respective effects. Although pretreatment of pediatric sarcoma cell lines with TNF did not improve unspecific peripheral blood mononuclear cells (PBMCs) cytotoxicity, TNF enhanced specific lysis of 1/3 HLA-A2+ EwS cell lines by CHM1319 CD8+ T cells depending on MHC-I expression and ICAM-1 upregulation.

Discussion

Our study supports utilization of TNF or TNF-inducing regimens for upregulation of MHC-I and costimulatory surface molecules on pediatric sarcoma cells and for enhancing recognition of responsive HLA-A2+ EwS tumor cells by antigen-specific CD8+ T cells.

Pharmacological targeting of P300/CBP reveals EWS::FLI1-mediated senescence evasion in Ewing sarcoma

Ewing sarcoma (ES) poses a significant therapeutic challenge due to the difficulty in targeting its main oncodriver, EWS::FLI1. We show that pharmacological targeting of the EWS::FLI1 transcriptional complex via inhibition of P300/CBP drives a global transcriptional outcome similar to direct knockdown of EWS::FLI1, and furthermore yields prognostic risk factors for ES patient outcome. We find that EWS::FLI1 upregulates LMNB1 via repetitive GGAA motif recognition and acetylation codes in ES cells and EWS::FLI1-permissive mesenchymal stem cells, which when reversed by P300 inhibition leads to senescence of ES cells. P300-inhibited senescent ES cells can then be eliminated by senolytics targeting the PI3K signaling pathway. The vulnerability of ES cells to this combination therapy suggests an appealing synergistic strategy for future therapeutic exploration.

Spatial multiplexed immunofluorescence analysis reveals coordinated cellular networks associated with overall survival in metastatic osteosarcoma

Patients diagnosed with advanced osteosarcoma, often in the form of lung metastases, have abysmal five-year overall survival rates. The complexity of the osteosarcoma immune tumor microenvironment has been implicated in clinical trial failures of various immunotherapies. The purpose of this exploratory study was to spatially characterize the immune tumor microenvironment of metastatic osteosarcoma lung specimens. Knowledge of the coordinating cellular networks within these tissues could then lead to improved outcomes when utilizing immunotherapy for treatment of this disease. Importantly, various cell types, interactions, and cellular neighborhoods were associated with five-year survival status. Of note, increases in cellular interactions between T lymphocytes, positive for programmed cell death protein 1, and myeloid-derived suppressor cells were observed in the 5-year deceased cohort. Additionally, cellular neighborhood analysis identified an Immune-Cold Parenchyma cellular neighborhood, also associated with worse 5-year survival. Finally, the Osteosarcoma Spatial Score, which approximates effector immune activity in the immune tumor microenvironment through the spatial proximity of immune and tumor cells, was increased within 5-year survivors, suggesting improved effector signaling in this patient cohort. Ultimately, these data represent a robust spatial multiplexed immunofluorescence analysis of the metastatic osteosarcoma immune tumor microenvironment. Various communication networks, and their association with survival, were described. In the future, identification of these networks may suggest the use of specific, combinatory immunotherapeutic strategies for improved anti-tumor immune responses and outcomes in osteosarcoma.

Unlocking the tumor-immune microenvironment in osteosarcoma: insights into the immune landscape and mechanisms

Osteosarcoma has a unique tumor microenvironment (TME), which is characterized as a complex microenvironment comprising of bone cells, immune cells, stromal cells, and heterogeneous vascular structures. These elements are intricately embedded in a mineralized extracellular matrix, setting it apart from other primary TMEs. In a state of normal physiological function, these cell types collaborate in a coordinated manner to maintain the homeostasis of the bone and hematopoietic systems. However, in the pathological condition, i.e., neoplastic malignancies, the tumor-immune microenvironment (TIME) has been shown to promote cancer cells proliferation, migration, apoptosis and drug resistance, as well as immune escape. The intricate and dynamic system of the TIME in osteosarcoma involves crucial roles played by various infiltrating cells, the complement system, and exosomes. This complexity is closely associated with tumor cells evading immune surveillance, experiencing uncontrolled proliferation, and facilitating metastasis. In this review, we elucidate the intricate interplay between diverse cell populations in the osteosarcoma TIME, each contributing uniquely to tumor progression. From chondroblastic and osteoblastic osteosarcoma cells to osteoclasts, stromal cells, and various myeloid and lymphoid cell subsets, the comprehensive single-cell analysis provides a detailed roadmap of the complex osteosarcoma ecosystem. Furthermore, we summarize the mutations, epigenetic mechanisms, and extracellular vesicles that dictate the immunologic landscape and modulate the TIME of osteosarcoma. The perspectives of the clinical implementation of immunotherapy and therapeutic approaches for targeting immune cells are also intensively discussed.

Dysregulation of Transposon Transcription Profiles in Cancer Cells Resembles That of Embryonic Stem Cells

Transposable elements (TEs) comprise a substantial portion of the mammalian genome, with potential implications for both embryonic development and cancer. This study aimed to characterize the expression profiles of TEs in embryonic stem cells (ESCs), cancer cell lines, tumor tissues, and the tumor microenvironment (TME). We observed similarities in TE expression profiles between cancer cells and ESCs, suggesting potential parallels in regulatory mechanisms. Notably, four TE RNAs (HERVH, LTR7, HERV-Fc1, HERV-Fc2) exhibited significant downregulation across cancer cell lines and tumor tissues compared to ESCs, highlighting potential roles in pluripotency regulation. The strong up-regulation of the latter two TEs (HERV-Fc1, HERV-Fc2) in ESCs has not been previously demonstrated and may be a first indication of their role in the regulation of pluripotency. Conversely, tandemly repeated sequences (MSR1, CER, ALR) showed up-regulation in cancer contexts. Moreover, a difference in TE expression was observed between the TME and the tumor bulk transcriptome, with distinct dysregulated TE profiles. Some TME-specific TEs were absent in normal tissues, predominantly belonging to LTR and L1 retrotransposon families. These findings not only shed light on the regulatory roles of TEs in both embryonic development and cancer but also suggest novel targets for anti-cancer therapy. Understanding the interplay between cancer cells and the TME at the TE level may pave the way for further research into therapeutic interventions.

CAR T cells redirected to B7-H3 for pediatric solid tumors: Current status and future perspectives

Despite intensive therapies, pediatric patients with relapsed or refractory solid tumors have poor outcomes and need novel treatments. Immune therapies offer an alternative to conventional treatment options but require the identification of differentially expressed antigens to direct antitumor activity to sites of disease. B7-H3 (CD276) is an immune regulatory protein that is expressed in a range of malignancies and has limited expression in normal tissues. B7-H3 is highly expressed in pediatric solid tumors including osteosarcoma, rhabdomyosarcoma, Ewing sarcoma, Wilms tumor, neuroblastoma, and many rare tumors. In this article we review B7-H3-targeted chimeric antigen receptor (B7-H3-CAR) T cell therapies for pediatric solid tumors, reporting preclinical development strategies and outlining the landscape of active pediatric clinical trials. We identify challenges to the success of CAR T cell therapy for solid tumors including localizing to and penetrating solid tumor sites, evading the hostile tumor microenvironment, supporting T cell expansion and persistence, and avoiding intrinsic tumor resistance. We highlight strategies to overcome these challenges and enhance the effect of B7-H3-CAR T cells, including advanced CAR T cell design and incorporation of combination therapies.

Deciphering the prognostic landscape of osteosarcoma: Integrating the roles of hippo pathway genes, programmed cell death, and the tumor immune microenvironment

Osteosarcoma is a highly aggressive cancer prevalent among adolescents and young adults, notorious for its tendency to metastasize to the lungs. This research delves into the molecular foundations of osteosarcoma by examining the role of the Hippo signaling pathway and its interaction with the tumor immune microenvironment (TME). Through analysis of transcriptomic data from the TARGET-OS dataset and control samples from GTEx, we identified a set of 131 genes that link high expression profiles in osteosarcoma with the Hippo pathway. A focused examination through univariate Cox regression analysis revealed eight key genes (DLG5, WNT11, TGFB2, DLG4, WNT16, ID2, WNT10B, and WNT10A) with a significant correlation to patient outcomes. Hierarchical clustering of these genes delineated two distinct patient groups with significantly different survival rates, a finding supported by Kaplan-Meier survival analysis. Further investigation into immune cell infiltration and expression profiles of immunoregulatory factors uncovered a notable pattern of immune evasion in the group with poorer prognosis, marked by reduced effector immune cell activity and lower levels of immunostimulatory factors. Single-cell sequencing highlighted the cellular diversity within osteosarcoma samples and identified markers differentiating malignant from nonmalignant cells, correlating these markers with prognostic risk scores. Our results emphasize the critical prognostic value of Hippo pathway genes and the TME in osteosarcoma, shedding light on new avenues for therapeutic intervention and patient-specific treatment strategies.

Single-cell RNA-seq reveals T cell exhaustion and immune response landscape in osteosarcoma

Background

T cell exhaustion in the tumor microenvironment has been demonstrated as a substantial contributor to tumor immunosuppression and progression. However, the correlation between T cell exhaustion and osteosarcoma (OS) remains unclear.

Methods

In our present study, single-cell RNA-seq data for OS from the GEO database was analysed to identify CD8+ T cells and discern CD8+ T cell subsets objectively. Subgroup differentiation trajectory was then used to pinpoint genes altered in response to T cell exhaustion. Subsequently, six machine learning algorithms were applied to develop a prognostic model linked with T cell exhaustion. This model was subsequently validated in the TARGETs and Meta cohorts. Finally, we examined disparities in immune cell infiltration, immune checkpoints, immune-related pathways, and the efficacy of immunotherapy between high and low TEX score groups.

Results

The findings unveiled differential exhaustion in CD8+ T cells within the OS microenvironment. Three genes related to T cell exhaustion (RAD23A, SAC3D1, PSIP1) were identified and employed to formulate a T cell exhaustion model. This model exhibited robust predictive capabilities for OS prognosis, with patients in the low TEX score group demonstrating a more favorable prognosis, increased immune cell infiltration, and heightened responsiveness to treatment compared to those in the high TEX score group.

Conclusion

In summary, our research elucidates the role of T cell exhaustion in the immunotherapy and progression of OS, the prognostic model constructed based on T cell exhaustion-related genes holds promise as a potential method for prognostication in the management and treatment of OS patients.

Oncogenic ETS fusions promote DNA damage and proinflammatory responses via pericentromeric RNAs in extracellular vesicles

Aberrant expression of the E26 transformation-specific (ETS) transcription factors characterizes numerous human malignancies. Many of these proteins, including EWS:FLI1 and EWS:ERG fusions in Ewing sarcoma (EwS) and TMPRSS2:ERG in prostate cancer (PCa), drive oncogenic programs via binding to GGAA repeats. We report here that both EWS:FLI1 and ERG bind and transcriptionally activate GGAA-rich pericentromeric heterochromatin. The respective pathogen-like HSAT2 and HSAT3 RNAs, together with LINE, SINE, ERV, and other repeat transcripts, are expressed in EwS and PCa tumors, secreted in extracellular vesicles (EVs), and are highly elevated in plasma of patients with EwS with metastatic disease. High human satellite 2 and 3 (HSAT2,3) levels in EWS:FLI1- or ERG-expressing cells and tumors were associated with induction of G2/M checkpoint, mitotic spindle, and DNA damage programs. These programs were also activated in EwS EV-treated fibroblasts, coincident with accumulation of HSAT2,3 RNAs, proinflammatory responses, mitotic defects, and senescence. Mechanistically, HSAT2,3-enriched cancer EVs induced cGAS-TBK1 innate immune signaling and formation of cytosolic granules positive for double-strand RNAs, RNA-DNA, and cGAS. Hence, aberrantly expressed ETS proteins derepress pericentromeric heterochromatin, yielding pathogenic RNAs that transmit genotoxic stress and inflammation to local and distant sites. Monitoring HSAT2,3 plasma levels and preventing their dissemination may thus improve therapeutic strategies and blood-based diagnostics.

Ewing sarcoma of the cervix: an unusual site of presentation

Ewing sarcoma is an exceedingly rare form of cancer that affects the cervix. It falls within the spectrum of neoplastic diseases known as Ewing's family of tumours, typically observed in osseous tissues. A woman in her 40s, experiencing symptoms of leucorrhoea and transvaginal bleeding that commenced 3 months before her consultation, was referred to our gynaecological oncology clinic with a preliminary diagnosis of ovarian teratoma. A colposcopy procedure was conducted unveiling a complete loss of cervical anatomy with friable and malodorous tissue. Pelvic ultrasound identified a lesion of uncertain origin in the cervix, suggestive of malignancy. Histopathological assessment of cervical biopsy specimens confirmed the presence of a small, round, blue cell neoplasm consistent with Ewing sarcoma. She underwent chemotherapy and pelvic radiotherapy, achieving complete remission 9 months after diagnosis, without experiencing any systemic adverse effects or sequelae.

Prognostic value of PRR11 and immune cell infiltration in Ewing sarcoma

Ewing's sarcoma (ES) is the second most common bone and soft tissue malignancy in children and adolescents with a poor prognosis. The identification of genes with prognostic value may contribute to the prediction and treatment of this disease. The GSE17679, GSE68776, GSE63155, and GSE63156 datasets were downloaded from the Gene Expression Omnibus database and qualified. Prognostic value of differentially expressed genes (DEGs) between the normal and tumor groups and immune cell infiltration were explored by several algorithms. A prognostic model was established and validated. Finally, functional analyses of the DEGs were performed. Proline rich 11 (PRR11) and mast cell infiltration were noted as the key indicators for the prognosis of ES. Kaplan-Meier and scatter plots for the training and two validation sets showed that patients in the low-PRR11 expression group were associated with better outcomes than those in the high-PRR11 expression group. The concordance indices and calibration analyses of the prognostic model indicated good predictive accuracy in the training and validation sets. The area under the curve values obtained through the receiver operating characteristic analysis for 1-, 3-, 5-year prediction were ≥ 0.75 in the three cohorts, suggesting satisfactory sensitivity and specificity of the model. Decision curve analyses suggested that patients could benefit more from the model than the other strategies. Functional analyses suggested that DEGs were mainly clustered in the cell cycle pathway. PRR11 and mast cell infiltration are potential prognostic indicators in ES. PRR11 possibly affects the prognosis of patients with ES through the cell cycle pathway.

Mesenchymal stromal cell derived extracellular vesicles as a therapeutic tool: immune regulation, MSC priming, and applications to SLE

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by a dysfunction of the immune system. Mesenchymal stromal cell (MSCs) derived extracellular vesicles (EVs) are nanometer-sized particles carrying a diverse range of bioactive molecules, such as proteins, miRNAs, and lipids. Despite the methodological disparities, recent works on MSC-EVs have highlighted their broad immunosuppressive effect, thus driving forwards the potential of MSC-EVs in the treatment of chronic diseases. Nonetheless, their mechanism of action is still unclear, and better understanding is needed for clinical application. Therefore, we describe in this review the diverse range of bioactive molecules mediating their immunomodulatory effect, the techniques and possibilities for enhancing their immune activity, and finally the potential application to SLE.

TCR-transgenic T cells and YB-1-based oncolytic virotherapy improve survival in a preclinical Ewing sarcoma xenograft mouse model

Background

Ewing sarcoma (EwS) is an aggressive and highly metastatic bone and soft tissue tumor in pediatric patients and young adults. Cure rates are low when patients present with metastatic or relapsed disease. Therefore, innovative therapy approaches are urgently needed. Cellular- and oncolytic virus-based immunotherapies are on the rise for solid cancers.

Methods

Here, we assess the combination of EwS tumor-associated antigen CHM1319-specific TCR-transgenic CD8+ T cells and the YB-1-driven (i.e. E1A13S-deleted) oncolytic adenovirus XVir-N-31 in vitro and in a xenograft mouse model for antitumor activity and immunostimulatory properties.

Results

In vitro both approaches specifically kill EwS cell lines in a synergistic manner over controls. This effect was confirmed in vivo, with increased survival using the combination therapy. Further in vitro analyses of immunogenic cell death and antigen presentation confirmed immunostimulatory properties of virus-infected EwS tumor cells. As dendritic cell maturation was also increased by XVir-N-31, we observed superior proliferation of CHM1319-specific TCR-transgenic CD8+ T cells only in virus-tested conditions, emphasizing the superior immune-activating potential of XVir-N-31.

Conclusion

Our data prove synergistic antitumor effects in vitro and superior tumor control in a preclinical xenograft setting. Combination strategies of EwS-redirected T cells and YB-1-driven virotherapy are a highly promising immunotherapeutic approach for EwS and warrant further evaluation in a clinical setting.

Molecular characterization of cancer-intrinsic immune evasion genes indicates prognosis and tumour microenvironment infiltration in osteosarcoma

Cancer-intrinsic immune evasion (IE) to cells is a critical factor in tumour growth and progression, yet the molecular characterization of IE genes (IEGs) in osteosarcoma remains underexplored. In this study, 85 osteosarcoma patients were comprehensively analyzed based on 182 IEGs, leading to the identification of two IE clusters linked to distinct biological processes and clinical outcomes. In addition, two IE clusters demonstrated diverse immune cell infiltration patterns, with IEGcluster A displaying increased levels compared to IEGcluster B. Moreover, an IE score was identified as an independent prognostic factor and nomogram may serve as a practical tool for the individual prognostic evaluation of patients with osteosarcoma. Finally, GBP1, a potential biomarker with high expression in osteosarcoma was identified. The findings of this study highlight the presence of two IE clusters, each associated with differing patient outcomes and immune infiltration properties. The IE score may serve to assess individual patient IE characteristics, enhance comprehension of immune features, and guide more efficacious treatment approaches.

Natural Killer Cell Activation by Ubiquitin-specific Protease 6 Mediates Tumor Suppression in Ewing Sarcoma

Ewing sarcoma is a rare and deadly pediatric bone cancer for which survival rates and treatment options have stagnated for decades. Ewing sarcoma has not benefited from immunotherapy due to poor understanding of how its immune landscape is regulated. We recently reported that ubiquitin-specific protease 6 (USP6) functions as a tumor suppressor in Ewing sarcoma, and identified it as the first cell-intrinsic factor to modulate the Ewing sarcoma immune tumor microenvironment (TME). USP6 induces intratumoral infiltration and activation of multiple innate immune lineages in xenografted nude mice. Here we report that natural killer (NK) cells are essential for its tumor-inhibitory functions, as NK cell depletion reverses USP6-mediated suppression of Ewing sarcoma xenograft growth. USP6 expression in Ewing sarcoma cells directly stimulates NK cell activation and degranulation in vitro, and functions by increasing surface levels of multiple NK cell-activating ligands. USP6 also induces surface upregulation of the receptor for the apoptosis-inducing ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), providing an additional route for enhanced sensitivity to NK cell killing. Furthermore, USP6-expressing Ewing sarcoma and NK cells participate in a paracrine immunostimulatory feedforward loop, wherein IFNγ secreted by activated NK cells feeds back on USP6/Ewing sarcoma cells to induce synergistic expression of chemokines CXCL9 and CXCL10. Remarkably, expression of USP6 in subcutaneous Ewing sarcoma xenografts induces systemic activation and maturation of NK cells, and induces an abscopal response in which growth of distal tumors is inhibited, coincident with increased infiltration and activation of NK cells. This work reveals how USP6 reprograms the Ewing sarcoma TME to enhance antitumor immunity, and may be exploited for future therapeutic benefit.

Significance

This study provides novel insights into the immunomodulatory functions of USP6, the only cancer cell-intrinsic factor demonstrated to regulate the immune TME in Ewing sarcoma. We demonstrate that USP6-mediated suppression of Ewing sarcoma tumorigenesis is dependent on NK cells. USP6 directly activates NK cell cytolytic function, inducing both intratumoral and systemic activation of NK cells in an Ewing sarcoma xenograft model.

The Eph/Ephrin system in primary bone tumor and bone cancer pain

The family of Eph receptor tyrosine kinases and their Ephrin ligands system constitutes a bidirectional signaling pathway. Eph/Ephrin system coordinate a wide spectrum of pathologic processes during development, metastasis, prognosis, drug resistance and angiogenesis in carcinogenesis. Chemotherapy, surgery and radiotherapy are the most commonly used clinical treatments for primary bone tumors. Therefore, surgical resection is often unable to completely eliminate the tumor, and this is the main cause of metastasis and postoperative recurrence. A growing body of literature has been published lately revitalizing our scientific interest towards the role of Eph/Ephrins in pathogenesis and the treatment of bone tumor and bone cancer pain. This study mainly reviewed the roles of Eph/Ephrin system that has both tumor-suppressing and -promoting roles in primary bone tumors and bone cancer pain. Understanding the intracellular mechanisms of Eph/Ephrin system in tumorigenesis and metastasis of bone tumors might provide a foundation for the development of Eph/Ephrin targeted anti-cancer therapy.

B7-H3 in Pediatric Tumors: Far beyond Neuroblastoma

B7-H3 is a 4Ig transmembrane protein that emerged as a tumor-associated antigen in neuroblastoma. It belongs to the B7 family, shows an immunoregulatory role toward NK and T cells, and, therefore, has been included in the growing family of immune checkpoints. Besides neuroblastoma, B7-H3 is expressed by many pediatric cancers including tumors of the central nervous system, sarcomas, and acute myeloid leukemia. In children, particularly those affected by solid tumors, the therapeutic protocols are aggressive and cause important life-threatening side effects. Moreover, despite the improved survival observed in the last decade, a relevant number of patients show therapy resistance and fatal relapses. Immunotherapy represents a new frontier in the cure of cancer patients and the targeting of tumor antigens or immune checkpoints blockade showed exciting results in adults. In this encouraging scenario, researchers and clinicians are exploring the possibility to use immunotherapeutics targeting B7-H3; these include mAbs and chimeric antigen receptor T-cells (CAR-T). These tools are rapidly evolving to improve the efficacy and decrease the unwanted side effects; drug-conjugated mAbs, bi-tri-specific mAbs or CAR-T, and, very recently, NK cell engagers (NKCE), tetra-specific molecules engaging a tumor-associated antigen and NK cells, have been generated. Preclinical data are promising, and clinical trials are ongoing. Hopefully, the B7-H3 targeting will provide important benefits to cancer patients.

Prospects and Advances in Adoptive Natural Killer Cell Therapy for Unmet Therapeutic Needs in Pediatric Bone Sarcomas

Malignant bone tumors are aggressive tumors, with a high tendency to metastasize, that are observed most frequently in adolescents during rapid growth spurts. Pediatric patients with malignant bone sarcomas, Ewing sarcoma and osteosarcoma, who present with progressive disease have dire survival rates despite aggressive therapy. These therapies can have long-term effects on bone growth, such as decreased bone mineral density and reduced longitudinal growth. New therapeutic approaches are therefore urgently needed for targeting pediatric malignant bone tumors. Harnessing the power of the immune system against cancer has improved the survival rates dramatically in certain cancer types. Natural killer (NK) cells are a heterogeneous group of innate effector cells that possess numerous antitumor effects, such as cytolysis and cytokine production. Pediatric sarcoma cells have been shown to be especially susceptible to NK-cell-mediated killing. NK-cell adoptive therapy confers numerous advantages over T-cell adoptive therapy, including a good safety profile and a lack of major histocompatibility complex restriction. NK-cell immunotherapy has the potential to be a new therapy for pediatric malignant bone tumors. In this manuscript, we review the general characteristics of osteosarcoma and Ewing sarcoma, discuss the long-term effects of sarcoma treatment on bones, and the barriers to effective immunotherapy in bone sarcomas. We then present the laboratory and clinical studies on NK-cell immunotherapy for pediatric malignant bone tumors. We discuss the various donor sources and NK-cell types, the engineering of NK cells and combinatorial treatment approaches that are being studied to overcome the current challenges in adoptive NK-cell therapy, while suggesting approaches for future studies on NK-cell immunotherapy in pediatric bone tumors.

The First-In-Class Anti-AXL×CD3ε Pronectin™-Based Bispecific T-Cell Engager Is Active in Preclinical Models of Human Soft Tissue and Bone Sarcomas

Sarcomas are heterogeneous malignancies with limited therapeutic options and a poor prognosis. We developed an innovative immunotherapeutic agent, a first-in-class Pronectin™-based Bispecific T-Cell Engager (pAXL×CD3ε), for the targeting of AXL, a TAM family tyrosine kinase receptor highly expressed in sarcomas. AXL expression was first analyzed by flow cytometry, qRT-PCR, and Western blot on a panel of sarcoma cell lines. The T-cell-mediated pAXL×CD3ε cytotoxicity against sarcoma cells was investigated by flow cytometry, luminescence assay, and fluorescent microscopy imaging. The activation and degranulation of T cells induced by pAXL×CD3ε were evaluated by flow cytometry. The antitumor activity induced by pAXL×CD3ε in combination with trabectedin was also investigated. In vivo activity studies of pAXL×CD3ε were performed in immunocompromised mice (NSG), engrafted with human sarcoma cells and reconstituted with human peripheral blood mononuclear cells from healthy donors. Most sarcoma cells showed high expression of AXL. pAXL×CD3ε triggered T-lymphocyte activation and induced dose-dependent T-cell-mediated cytotoxicity. The combination of pAXL×CD3ε with trabectedin increased cytotoxicity. pAXL×CD3ε inhibited the in vivo growth of human sarcoma xenografts, increasing the survival of treated mice. Our data demonstrate the antitumor efficacy of pAXL×CD3ε against sarcoma cells, providing a translational framework for the clinical development of pAXL×CD3ε in the treatment of human sarcomas, aggressive and still-incurable malignancies.

Immunotherapy for Solid Tumors

The development of immune checkpoint inhibitors (ICIs) constitutes a major therapeutic advance in the treatment of a number of malignancies [...].

Bacteria associated with glioma: a next wave in cancer treatment

Malignant gliomas occur more often in adults and may affect any part of the central nervous system (CNS). Although their results could be better, surgical excision, postoperative radiation and chemotherapy, and electric field therapy are today's mainstays of glioma care. However, bacteria can also exert anti-tumor effects via mechanisms such as immune regulation and bacterial toxins to promote apoptosis, inhibit angiogenesis, and rely on their natural characteristics to target the tumor microenvironment of hypoxia, low pH, high permeability, and immunosuppression. Tumor-targeted bacteria expressing anticancer medications will go to the cancer site, colonize the tumor, and then produce the therapeutic chemicals that kill the cancer cells. Targeting bacteria in cancer treatment has promising prospects. Rapid advances have been made in the study of bacterial treatment of tumors, including using bacterial outer membrane vesicles to load chemotherapy drugs or combine with nanomaterials to fight tumors, as well as the emergence of bacteria combined with chemotherapy, radiotherapy, and photothermal/photodynamic therapy. In this study, we look back at the previous years of research on bacteria-mediated glioma treatment and move forward to where we think it is headed.