Cell Sarcoma Research Articles

Lymphoid Aggregates in Canine Cutaneous and Subcutaneous Sarcomas: Immunohistochemical and Gene Expression Evidence for Tertiary Lymphoid Structures.

Canine cutaneous/subcutaneous soft-tissue sarcomas (STS) are diversely derived mesenchymal neoplasms with a risk of recurrence and/or metastasis depending on the extent of surgical excision and histologic grade. Lymphoid aggregates (LAs) are often described in these tumours but not characterised. In humans, LA characterised as tertiary lymphoid structures (TLSs) improve the prognosis of many tumours, including sarcomas. We sought to determine if LA meeting a size criterion (> 700 cells) in canine sarcomas met the criteria of TLS and the overall prevalence of LA of any size. RNA expression in large LAs versus aggregate-adjacent sarcoma tissue (AAS) was measured in laser capture microdissected tissue and compared to curl-derived RNA from aggregate-free sarcomas and lymph nodes. CD3, CD20, MUM-1 and PNAd expressions were measured using immunohistochemistry. CD20 and CD3 mRNA were more highly expressed in LA versus AAS (13.8 fold, p = 0.0003 and 2.3 fold, p = 0.043). This was supported by the IHC findings. The large LAs were also enriched in chemokine RNA expression characteristic of TLS (CXCR5 5.8 fold, p < 00001, CCL19 3.68 fold, p = 0.0209, CCL21 6.87 fold, p = 0.0209 and CXCL13 2.68 fold, p = 0.0924). Plasma cells and high endothelial venules were identified in LA containing tumours but not in control tissue. Large LAs were present in 12% of tumours, and LA of any size in 30%. We conclude that large LAs in canine STS are consistent with TLS.

Panobinostat Synergizes with Chemotherapeutic Agents and Improves Efficacy of Standard-of-Care Chemotherapy Combinations in Ewing Sarcoma Cells

Background: The survival rate of patients with Ewing sarcoma (EWS) has seen very little improvement over the past several decades and remains dismal for those with recurrent or metastatic disease. HDAC2, ALK, JAK1, and CDK4 were identified as potential targets using RNA sequencing performed on EWS patient tumors with the bioinformatic analysis of gene expression. Methods/Results: The pan-HDAC inhibitor Panobinostat was cytotoxic to all the Ewing sarcoma cell lines tested. Mechanistically, Panobinostat decreases the expression of proteins involved in the cell cycle, including Cyclin D1 and phospho-Rb, and DNA damage repair, including CHK1. Further, Panobinostat induces a G1 cell cycle arrest. The combination of Panobinostat with Doxorubicin or Etoposide, both of which are used as standard of care in upfront treatment, leads to a synergistic effect in EWS cells. The combination of Panobinostat and Doxorubicin induces an accumulation of DNA damage, a decrease in the expression of DNA damage repair proteins CHK1 and CHK2, and an increase in caspase 3 cleavage. The addition of Panobinostat to standard-of-care chemotherapy combinations significantly reduces cell viability compared to that of chemotherapy alone. Conclusions: Overall, our data indicate that HDAC2 is overexpressed in many EWS tumor samples and HDAC inhibition is effective in targeting EWS cells, alone and in combination with standard-of-care chemotherapy agents. This work suggests that the addition of an HDAC inhibitor to upfront treatment may improve response.

Assessing sarcoma cell cytoskeleton remodeling in response to varying collagen concentration

Sarcomas, rare malignant tumors of mesenchymal origin, are often underdiagnosed and have face diagnostic ambiguities and limited treatment options. The main objective of this study was to define the nanomechanical and biophysical properties of sarcoma cells, particularly examining how the cytoskeleton's remodeling and related cellular processes such as cell migration and invasion in response to environmental stimuli due to collagen content. Utilizing one murine fibrosarcoma and one osteosarcoma cell line we employed atomic force microscopy, immunostaining, advanced image processing, in vitro cellular assays, and molecular techniques to investigate cells' cytoskeleton remodeling in response to varying collagen concentration. Our study focused on how alterations in collagen content affects the cytoskeletal dynamics and correlate with changes in gene expression profiles relevant to metastasis and an aggressive cancer phenotypes. Our findings indicate that despite their shared classification, fibrosarcoma and osteosarcoma cells display distinct biophysical properties and respond differently to mechanical forces. Notably, this difference in cellular behavior renders mechanical properties a potent novel biomarkers. Furthermore, the metastasis-related identified genes related to metastatic capability, could be potential therapeutic targets. This study highlights the significance of understanding the unique traits of sarcoma cells to improve diagnostic precision and expand therapeutic strategies, for this rare type of cancer.

Cell-cycle phase progression analysis identifies three unique phenotypes in soft tissue sarcoma

PurposeLoddo et al. (Br J Cancer 100:959–70, 2009) established the prognostic significance of cell cycle markers and "Cell-Cycle Phenotypes" in breast carcinoma. This study aims to 1) identify prognostic cell-cycle markers in sarcoma, and 2) assess the prognostic potential of specific cell-cycle phenotypes in sarcoma.MethodsTissue samples from 128 soft tissue sarcomas were stained for four cell cycle-specific markers: Mcm2, Geminin, Plk1, and H3S10ph. Only primary soft tissue tumors (liposarcoma, leiomyosarcoma, synovial sarcoma, and undifferentiated pleomorphic sarcoma) were included in the analysis. Any tumor coming from a recurrent or metastatic lesion were excluded from the analysis. Three cell-cycle phenotypes (I, II, III) were derived from marker expression patterns. Prognostic significance was evaluated in a subset of primary soft tissue sarcomas using Cox regression for survival analysis.ResultsCompared to phenotype I, the phenotype III tumors had a decreased 5-year overall survival (HR 6.81 [2.36–19.61]; p = < 0.001), 5-year disease-free survival (HR 1.07 (1.02–1.18); p = 0.004), and 5-year metastasis-free survival (HR 4.34 [1.58–11.93]; p = 0.004).High expression of Plk1 was associated with decreased 5-year overall survival (HR: 4.04 CI [1.21–6.67; p = 0.02) and 5-year metastasis-free survival (HR: 2.91 CI [1.15–7.37]; p = 0.03). Geminin was also found to have a decreased 5-year overall survival (HR:2.84 CI [1.21–6.67]; p = 0.02). No statistical difference in prognostication were noted between phenotypes and the AJCC system.ConclusionsWe identified three unique sarcoma cell cycle phenotypes that have prognostic significance. This performs similarly to the AJCC staging system.

Assessment of a Structurally Modified Alternanthera Mosaic Plant Virus as a Delivery System for Sarcoma Cells

The virions of plant viruses and their structurally modified particles (SP) represent valuable platforms for recombinant vaccine epitopes and antitumor agents. The possibility of modifying their surface with biological compounds makes them a tool for developing medical biotechnology applications. Here, we applied a new type of SP derived from virions and virus-like particles (VLP) of Alternanthera mosaic virus (AltMV) and well-studied SP from Tobacco mosaic virus (TMV). We have tested the ability of SP from AltMV (AltMV SPV) and TMV virions also as AltMV VLP to bind to and penetrate Ewing sarcoma cells. The adsorption properties of AltMV SPV and TMV SP are greater than those of the SP from AltMV VLP. Compared to normal cells, AltMV SPV adsorbed more effectively on patient-derived sarcoma cells, whereas TMV SP were more effective on the established sarcoma cells. The AltMV SPV and TMV SP were captured by all sarcoma cell lines. In the established Ewing sarcoma cell line, the effectiveness of AltMV SPV penetration was greater than that of TMV SP. The usage of structurally modified plant virus particles as a platform for drugs and delivery systems has significant potential in the development of anticancer agents.

Case Report : Undifferentiated Synovial Sarcoma Presenting as a Large Thoracic Mass: A Rare and Challenging Diagnosis

Background: Undifferentiated synovial sarcoma (USS) is a rare and aggressive subtype of soft tissue sarcoma. Its presentation as a large thoracic mass poses significant diagnostic and therapeutic challenges.  Case Presentation: A 34-year-old male presented with a three-month history of progressive chest pain and hemoptysis. Imaging studies revealed a large, cystic thoracic mass with pleural effusion. Initial serological testing suggested hydatid cyst, but subsequent testing revealed negative Echinococcus (Hydatid) IgG antibodies.  Diagnostic and Therapeutic Interventions: Repeat fine-needle aspiration cytology (FNAC) was deferred due to revised ultrasound findings indicating a solid fibrocystic vascular lesion. Bronchial artery embolization (BAE) was performed to control life- threatening hemorrhage. Thoracotomy and en-bloc mass excision were subsequently undertaken.  Histopathological Diagnosis: Histopathological examination of the resected specimen revealed undifferentiated synovial sarcoma and spindle cell sarcoma.  Clinical Implications: This case highlights the importance of correlating imaging and serological findings, managing vascular complications, and the efficacy of BAE in controlling hemorrhage. The significance of thoracotomy and mass excision in achieving diagnostic clarity and therapeutic success is underscored.  Conclusion: Undifferentiated synovial sarcoma presenting as a large thoracic mass poses significant diagnostic and therapeutic challenges. A multidisciplinary approach, incorporating imaging, serological testing, and surgical intervention, is crucial for achieving optimal patient outcomes.

High dose chemotherapy with autologous stem cell rescue in children and young adults with high-risk Ewing sarcoma: A single institute experience in Taiwan.

A combination treatment of surgery, chemotherapy, and radiotherapy can improve the survivals of pediatric patients with Ewing sarcoma (ES). However, prognosis remains poor for patients with metastatic disease at diagnosis or recurrence. Other high-risk (HR) features include large tumor burden, tumors of the axial skeleton and poor histologic response. Several studies have documented high dose chemotherapy with autologous stem cell rescue (HDC-ASCR) to be effective in such patients. In this retrospective study, we present the results of HDC-ASCR for high-risk Ewing sarcoma in children and young adults in a single institute. From March 2004 to March 2021, patients with ES, Ewing-like sarcoma, or round cell sarcoma received HDC-ASCR as part of treatment were included. The patients' characteristics, disease status, stem cell dose, engraftment status, post-transplant complications, and outcomes were analyzed. Twenty patients receiving HDC-ASCR at complete response (n = 6), partial response (n = 13), and stable disease (n = 1) were enrolled. The male to female ratio was 11:9. Median age at diagnosis and transplant was 15.6 years old (range: 3.3-28.9) and 16.2 (range: 4.2-29.9), respectively. The conditioning regimens included ifosfamide-based in two and melphalan-based in 19. All patients achieved successful engraftment without tansplant-related mortality. The 5-year progression-free and overall survival (OS) rate were 35% and 54.5%, respectively. The causes of death (n = 8) were all contributed to disease progression. Patients in the complete response group or with localized HRES exhibited a higher 5-year OS (p = 0.047 and 0.05, respectively). Compared to the historical cohort without HDC-ASCR as part of primary treatment, the current cohort had a significantly better 5-year OS (p = 0.018). HDC-ASCR seems promising as an alternative treatment for HRES in improving OS in this retrospective study with limited case number.

Postoperative challenges addressed through nursing care of patients receiving lower extremity tumor prosthesis

BackgroundPatients with primary Bone Sarcoma and Giant Cell Tumors in the lower extremities often require major surgery involving tumor prostheses. The postoperative course for this patient group can be complex and influenced by various factors and challenges that demand careful nursing care. This study aims to identify challenges related to the nursing care of individuals with primary bone tumors following surgery for tumor prostheses in the lower extremities.MethodsA retrospective cohort study of 15 patients treated at Rigshospitalet, Copenhagen, Denmark, between November 5. 2016, and April 1. 2020 was conducted by medical record review, focusing on challenges related to postoperative nursing care. All patients with the surgery code “Bone Excision” were identified within the surgery booking system and screened for eligibility.ResultsPatients experienced postoperative challenges such as severe pain, prolonged time to mobilization (mean: 4 days), and defecation (mean: 5 days). The mean length of stay at the Rigshospitalet was 13 days. Furthermore, eleven patients (73%) reported disrupted sleep and nausea.ConclusionPatients undergoing tumor prosthesis surgery in the lower extremities face considerable postoperative challenges that contribute to a prolonged hospital stay. These challenges, including severe pain, delayed mobilization, and gastrointestinal issues, significantly impact recovery. The findings highlight the urgent need for targeted nursing interventions to address these issues effectively. Enhanced pain management protocols, early mobilization strategies, and comprehensive postoperative care plans are essential to improve patient outcomes and reduce the length of hospital stays. Addressing these challenges through dedicated nursing care is crucial for optimizing the recovery process for patients receiving lower extremity tumor prostheses.

Pediatric soft tissue tumors : Tumors of uncertain origin

Soft tissue tumors of childhood are an extremely heterogeneous group of tumors that require precise diagnosis for therapy. In this article, selected tumors of uncertain origin that exhibit characteristic histological, immunophenotypical, and molecular features are addressed. Angiomatoid fibrous histiocytoma, alveolar soft part sarcoma, extrarenal rhabdoid tumor, synovial sarcoma, and desmoplastic small round cell tumor differ in their pathology, their clinical behavior, and prognosis.

Establishment and characterization of 18 Sarcoma Cell Lines: Unraveling the Molecular Mechanisms of Doxorubicin Resistance in Sarcoma Cell Lines

Sarcomas, malignant tumors from mesenchymal tissues, exhibit poor prognosis despite advancements in treatment modalities such as surgery, radiotherapy, and chemotherapy, with doxorubicin being a cornerstone treatment. Resistance to doxorubicin remains a significant hurdle in therapy optimization. This study aims to dissect the molecular bases of doxorubicin resistance in sarcoma cell lines, which could guide the development of tailored therapeutic strategies. Eighteen sarcoma cell lines from 14 patients were established under ethical approvals and classified into seven subtypes. Molecular, genomic, and transcriptomic analyses included whole-exome sequencing, RNA sequencing, drug sensitivity assays, and pathway enrichment studies to elucidate the resistance mechanisms. Variability in doxorubicin sensitivity was linked to specific genetic alterations, including mutations in TP53 and variations in the copy number of genomic loci like 11q24.2. Transcriptomic profiling divided cell lines into clusters by karyotype complexity, influencing drug responses. Additionally, pathway analyses highlighted the role of signaling pathways like WNT/BETA-CATENIN and HEDGEHOG in doxorubicin-resistant lines. Comprehensive molecular profiling of sarcoma cell lines has revealed complex interplays of genetic and transcriptomic factors dictating doxorubicin resistance, underscoring the need for personalized medicine approaches in sarcoma treatment. Further investigations into these resistance mechanisms could facilitate the development of more effective, customized therapy regimens.

IInduction of G2/M Phase Block and Apoptosis by Kaempferol in Human Sarcoma Cells

malignant cells has interested us to seek new strategies for the treatment of sarcoma. Flavonoids have been recently claimed to exert anti-cancer effects. We focused on the flavonoid kaempferol, to determine whether it induces apoptosis of sarcoma cells in vitro. Methods: We examined cell growth using a CCK-8 assay, morphology, cell cycle analysis, and the apoptosis or differentiation effects of kaempferol on cultured human osteosarcoma MG-63 cells. All experiments were performed at least three times in duplicates. The ANOVA and independent sample t-test were used for the comparison of the continuous variables Results: Kaempferol (50 μM), adversely affected the proliferation of MG-63 cells. Anti-proliferative action of kaempferol appeared to be linked to apoptotic cell death based on the morphological changes depicting nuclear fragmentation. Cell cycle analysis demonstrated the induction of G2/M phase arrest and an enhanced sub-G1 population. However, the intracellular alkaline phosphatase (ALP) activity was observed to have been stimulated. This apoptosis might be associated with cell differentiation of the cells in the early stage. Conclusions: This study demonstrates that kaempferol inhibited the growth of MG-63 cells in vitro. G2/M phase arrest and induction of intracellular ALP activities in the early phase are observed. These findings indicate that kaempferol may present as an additional pharmacological tool for the treatment of human sarcoma cells.

Fabrication of mRNA encapsulated lipid nanoparticles using state of the art SMART-MaGIC technology and transfection in vitro

The messenger ribose nucleic acid (mRNA) in the form of Corona virus of 2019 (COVID-19) vaccines were effectively delivered through lipid nanoparticles (LNP) proving its use as effective carriers in clinical applications. In the present work, mRNA (erythropoietin (EPO)) encapsulated LNPs were prepared using a next generation state-of-the-art patented, Sprayed Multi Absorbed-droplet Reposing Technology (SMART) coupled with Multi-channeled and Guided Inner-Controlling printheads (MaGIC) technologies. The LNP-mRNA were synthesized at different N/P ratios and the particles were characterized for particle size and zeta potential (Zetasizer), encapsulation or complexation (gel retardation assay) and transfection (Fluorescence microscopy and ELISA) in MG63 sarcoma cells in vitro. The results showed a narrow distribution of mRNA-lipid particles of 200 nm when fabricated with SMART alone and then the size was reduced to approximately 50 nm with the combination of SMART-MaGIC technologies. The gel retardation assay showed that the N/P > 1 exhibited strong encapsulation of mRNA with lipid. The in vitro results showed the toxicity profile of the lipids where N/P ratio of 5 was optimized with > 50% cell viability. It can be concluded that the functional LNP-mRNA prepared and analyzed with SMART-MaGIC technologies, could be a potential new fabrication method of mRNA loaded LNPs for point-of-service or distributed manufacturing.

Aberrant positivity for BCOR immunohistochemistry in merkel cell carcinoma - a potential diagnostic pitfall

BackrgoundMerkel cell carcinoma (MCC) is a rare, aggressive primary cutaneous neuroendocrine carcinoma, frequently associated with clonal Merkel cell polyomavirus integration. MCC can pose significant diagnostic challenges due to its diverse clinical presentation and its broad histological differential diagnosis. Histologically, MCC presents as a small-round-blue cell neoplasm, where the differential diagnosis includes basal cell carcinoma, melanoma, hematologic malignancies, round cell sarcoma and metastatic small cell carcinoma of any site. We here report strong aberrant immunoreactivity for BCOR in MCC, a marker commonly used to identify round cell sarcomas and other neoplasms with BCOR alterations.MethodsBased on strong BCOR expression in three index cases of MCC, clinically mistaken as sarcoma, a retrospective analysis of three patient cohorts, comprising 31 MCC, 19 small cell lung carcinoma (SCLC) and 5 cases of neoplasms with molecularly confirmed BCOR alteration was conducted. Immunohistochemical staining intensity and localization for BCOR was semi-quantitatively analyzed.ResultsThree cases, clinically and radiologically mimicking a sarcoma were analyzed in our soft tissue and bone pathology service. Histologically, the cases showed sheets of a small round blue cell neoplasm. A broad panel of immunohistochemistry was used for lineage classification. Positivity for synaptophysin, CK20 and Merkel cell polyoma virus large T-antigen lead to the diagnosis of a MCC. Interestingly, all cases showed strong positive nuclear staining for BCOR, which was included for the initial work-up with the clinical differential of a round cell sarcoma. We analyzed a larger retrospective MCC cohort and found aberrant weak to strong BCOR positivity (nuclear and/or cytoplasmic) in up to 90% of the cases. As a positive control, we compared the expression to a small group of BCOR-altered neoplasms. Furthermore, we investigated a cohort of SCLC as another neuroendocrine neoplasm and found in all cases a diffuse moderate to strong BCOR positivity.ConclusionsThis study demonstrates that neuroendocrine neoplasms, such as MCC and SCLC can express strong aberrant BCOR. This might represent a diagnostic challenge or pitfall, in particular when MCC is clinically mistaken as a soft tissue or a bone sarcoma.

Linear energy transfer dependent variation in viability and proliferation along the Bragg peak curve in sarcoma and normal tissue cells

Objective.The energy deposition of photons and protons differs. It depends on the position in the proton Bragg peak (BP) and the linear energy transfer (LET) leading to a variable relative biological effectiveness (RBE). Here, we investigate LET dependent alterations on metabolic viability and proliferation of sarcoma and endothelium cell lines following proton irradiation in comparison to photon exposure.Approach.Using a multi-step range shifter, each column of a 96-well plate was positioned in a different depth along four BP curves with increasing intensities. The high-throughput experimental setup covers dose, LET, and RBE changes seen in a treatment field. Photon irradiation was performed to calculate the RBE along the BP curve. Two biological information out of one experiment were extracted allowing a correlation between metabolic viability and proliferation of the cells.Main results.The metabolic viability and cellular proliferation were column-wise altered showing a depth-dose profile. Endothelium cell viability recovers within 96 h post BP irradiation while sarcoma cell viability remains reduced. Highest RBE values were observed at the BP distal fall-off regarding proliferation of the sarcoma and endothelial cells.Significance.The high-throughput experimental setup introduced here (I) covers dose, LET, and RBE changes seen in a treatment field, (II) measures short-term effects within 48 h to 96 h post irradiation, and (III) can additionally be transferred to various cell types without time consuming experimental adaptations. Traditionally, RBE values are calculated from clonogenic cell survival. Measured RBE profiles strongly depend on physical characteristics such as dose and LET and biological characteristics for example cell type and time point. Metabolic viability and proliferation proofed to be in a similar effect range compared to clonogenic survival results. Based on limited data of combined irradiation with doxorubicin, future experiments will test combined treatment with systemic therapies applied in clinics e.g. cyclin-dependent inhibitors.

Identification of ENO‐1 positive extracellular vesicles as a circulating biomarker for monitoring of Ewing sarcoma

AbstractThe lack of circulating biomarkers for tumor monitoring is a major problem in Ewing sarcoma management. The development of methods for accurate tumor monitoring is required, considering the high recurrence rate of drug‐resistant Ewing sarcoma. Here, we describe a sensitive analytical technique for tumor monitoring of Ewing sarcoma by detecting circulating extracellular vesicles secreted from Ewing sarcoma cells. Proteomic analysis of Ewing sarcoma cell‐derived extracellular vesicles identified 564 proteins prominently observed in extracellular vesicles from three Ewing sarcoma cell lines. Among these, CD99, SLC1A5, and ENO‐1 were identified on extracellular vesicles purified from sera of patients with Ewing sarcoma before treatment but not on extracellular vesicles from those after treatment and healthy individuals. Notably, not only Ewing sarcoma‐derived extracellular vesicles but also Ewing sarcoma cells demonstrated proteomic expression of CD99 and ENO‐1 on their surface membranes. ENO‐1+CD63+ extracellular vesicle detection was reduced after tumor resection while both CD99+CD63+ and ENO‐1+CD63+ extracellular vesicles were detected in serum from Ewing sarcoma‐bearing mice. Finally, the accuracy of liquid biopsy targeting these candidates was assessed using extracellular vesicles from the sera of patients with Ewing sarcoma. Elevated ENO‐1+CD81+ extracellular vesicles in the serum of patients before treatments distinguished patients with Ewing sarcoma from healthy individuals with an area under the curve value of 0.92 (P &lt; 0.001) and reflected the tumor burden in patients with Ewing sarcoma during multidisciplinary treatments. Collectively, circulating ENO‐1+CD81+ extracellular vesicle detection could represent a novel tool for tumor monitoring of Ewing sarcoma.

Abstract B053: Tumor-associated macrophages diminishes IL1RAP-targeting CAR-T cell therapy efficacy in Ewing sarcoma

Abstract Ewing sarcoma (EwS) is a pediatric malignancy of soft tissue and bone with a poor prognosis, especially in its metastatic stages. We have previously identified IL1RAP as a promising target for immunotherapies like chimeric antigen receptor (CAR) T cell therapy against EwS. However, CAR-T cells, despite their success in hematological cancers, often show limited efficacy against solid tumors. In orthotopic xenograft models of Ewing sarcoma (EwS) we have observed that CD11b+ CD206+ macrophages, known as tumor-associated macrophages (TAMs), surround the primary tumor. Treatment with IL1RAP-targeting CAR-T cells specific to EwS results in T cells localizing with these macrophages and failing to infiltrate the primary tumor. This study aims to characterize the impact of TAMs on CAR-T cell efficacy in EwS. We hypothesized that TAMs, polarized by Ewing sarcoma cells, suppress IL1RAP CAR-T cell activity. To model these interactions, we co-cultured EwS cells, macrophages, and CAR-T cells, performing luciferin-based in vitro cytotoxicity assays. THP-1 monocytes were differentiated into macrophages and polarized into M1 or M2 states using cytokines (LPS + IFN-y, IL-4 + IL-13), or differentiated into TAMs by co-culture with EwS cell lines. In vitro cytotoxicity assays were conducted using luciferase-expressing EwS target cells, polarized THP-1 macrophages, and IL1RAP CAR-T effector cells, with luminescence indicating EwS cell survival. We found that M1 macrophages did not affect CAR-T cell targeting of EwS cells, whereas M2 macrophages and TAMs significantly decreased specific lysis (p &amp;lt; 0.001). Conditioned media from polarized macrophages had no effect on CAR-T cell performance against EwS, suggesting that physical proximity or direct contact with TAMs is necessary to suppress CAR-T cell function. Western blot analysis of polarized THP-1 macrophages revealed that M2-polarized macrophages upregulated IL1RAP expression compared to M1 macrophages. Ongoing experiments aim to determine whether elevated IL1RAP expression in M2 macrophages redirects IL1RAP CAR-T cells away from EwS cells or if M2 macrophages mediate general suppression of CAR-T cell activity. Additionally, we are investigating whether THP-1-derived TAMs and primary macrophages also upregulate IL1RAP expression when polarized and how this affects syngeneic CAR-T cell performance. Our findings indicate that TAMs can influence the efficacy of IL1RAP-targeting CAR-T cells against EwS. Further investigation into the specific mechanisms responsible for this suppressive effect could enhance CAR-T therapy for Ewing sarcoma and potentially other solid tumors. Citation Format: Yue Zhou (Joe) Huang, Melanie Rouleu, Poul Sorensen. Tumor-associated macrophages diminishes IL1RAP-targeting CAR-T cell therapy efficacy in Ewing sarcoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pediatric Cancer Research; 2024 Sep 5-8; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl):Abstract nr B053.

Abstract A062 Therapeutic targeting of the SAGA KAT module impairs MYCN-amplified neuroblastoma growth through reduction of the MYCN oncogenic gene expression program

Abstract Pediatric cancers are frequently driven by genomic alterations that result in aberrant transcription factor activity. While direct targeting of transcription factors is difficult, one method to circumvent this problem is to target co-factors and chromatin complexes that are necessary for their oncogenic function. To evaluate protein complex dependencies enriched in MYCN-amplified neuroblastoma, a disease of dysregulated development driven by aberrant expression of an oncogenic expression program, we curated a list of protein complexes using the CORUM database and mined the Dependency Map using single sample gene set enrichment analysis. This analysis identified the KAT module of the transcriptional coactivator Spt-Ada-Gcn5-acetyltransferase (SAGA) complex as a selective dependency in MYCN-amplified neuroblastoma. Loss of SAGA complex activity in neuroblastoma through both genetic knockout and induced protein degradation of the lysine acetyltransferase (KAT) module subunit TADA2B resulted in a global reduction of histone lysine acetylation and impaired neuroblastoma cell growth. Genetic knockout of TADA2B did not impair the growth of pediatric sarcoma cell lines, suggesting that SAGA loss-of-function is not broadly deleterious. Furthermore, SAGA loss-of-function reduced MYCN binding to chromatin, resulting in suppression of the MYCN-driven gene expression program and impaired cell cycle progression. Importantly, the SAGA complex is pharmacologically targetable in vitro and in vivo with GSK-699, a PROTAC that induces proteolysis of both KAT2A and KAT2B paralogs. As observed with genetic knockout studies, loss of SAGA activity through KAT2A/B degradation reduced the MYCN-driven transcriptional signature and impaired cell cycle progression. Our findings expand our understanding of the chromatin complexes that maintain the oncogenic transcriptional state in MYCN-amplified neuroblastoma and suggest therapeutic potential for inhibitors of SAGA KAT activity in MYCN-amplified neuroblastoma. Citation Format: Nathaniel W. Mabe, Clare F. Malone, Alexandra B. Forman, Gabriela Alexe, Kathleen L. Engel, Ying-Jiun C. Chen, Melinda Soeung, Silvi Salhotra, Allen Basanthakumar, Bin Liu, Sharon YR Dent, Kimberly Stegmaier. Therapeutic targeting of the SAGA KAT module impairs MYCN-amplified neuroblastoma growth through reduction of the MYCN oncogenic gene expression program [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pediatric Cancer Research; 2024 Sep 5-8; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl):Abstract nr A062.

Mitoregulin modulates inflammation in osteoarthritis: Insights from synovial transcriptomics and cellular studies

Osteoarthritis is a prevalent musculoskeletal disease that involves cartilage degradation, subchondral bone remodeling, and synovial inflammation and ultimately causes physical disability. Common risk factors for osteoarthritis include age, sex, obesity, and genetic predispositions. Treatment includes nonpharmaceutical and pharmacological approaches; however, disease-modifying osteoarthritis drugs remain undeveloped. We aimed to identify key regulatory factors underlying the etiology of osteoarthritis. We studied alterations of the inflammatory responses after manipulating the expression of MTLN, which we selected after sequencing and transcriptomics of the patients’ synovial tissues. MTLN expression was increased in synovial tissues of patients and in SW982 human synovial sarcoma cells following inflammatory stimuli. We found that MTLN overexpression or knockout respectively decreased or increased expression of the inflammation-associated genes, including IL-6, IL-8, and TNF-α. Thus, high levels of MTLN in osteoarthritis may protect tissues against excessive inflammation, thereby offering therapeutic potentials.

Targeting Death Receptor 5 (DR5) for the imaging and treatment of primary bone and soft tissue tumors: an update of the literature.

Death Receptor 5 (DR5) is expressed on the surface of primary bone and soft tissue sarcoma cells, and its activation induces cell death primarily through apoptosis. The combination of DR5 agonists and commonly used chemotherapeutic agents, such as doxorubicin, can promote cell death. Currently, clinical trials are investigating the effectiveness of DR5 activation using new biological agents, such as bi-specific or tetravalent antibodies, in improving the survival of patients with relapsed or refractory cancers. Furthermore, investigations continue into the use of novel combination therapies to enhance DR5 response, for example, with inhibitor of apoptosis protein (IAP) antagonist agents [such as the second mitochondria-derived activator of caspase (SMAC) mimetics] and with immune checkpoint inhibitor anti-programmed death-ligand 1 (anti-PD-L1) or anti-programmed cell death-1 (anti-PD-1) antibodies. Other therapies include nanoparticle-mediated delivery of TRAIL plasmid DNA or TRAIL mRNA and stem cells as a vehicle for the targeted delivery of anti-cancer agents, such as TRAIL, to the tumor. Scoping review of the literature from November 2017 to March 2024, utilizing PubMed and Google Scholar. New agents under investigation include nanoTRAIL, anti-Kv10.1, multimeric IgM, and humanized tetravalent antibodies. Developments have been made to test novel agents, and imaging has been used to detect DR5 in preclinical models and patients. The models include 3D spheroids, genetically modified mouse models, a novel jaw osteosarcoma model, and patient-derived xenograft (PDX) animal models. There are currently two ongoing clinical trials focusing on the activation of DR5, namely, IGM-8444 and INBRX-109, which have progressed to phase 2. Further modifications of TRAIL delivery with fusion to single-chain variable fragments (scFv-TRAIL), directed against tumor-associated antigens (TAAs), and in the use of stem cells focus on targeted TRAIL delivery to cancer cells using bi-functional strategies. In vitro, in vivo, and clinical trials, as well as advances in imaging and theranostics, indicate that targeting DR5 remains a valid strategy in the treatment of some relapsed and refractory cancers.

1784TiP Pasireotide as maintenance treatment in SSTR2/3/5-expressing synovial sarcoma and desmoplastic small round cell tumor: The PAMSARC study

1784TiP Pasireotide as maintenance treatment in SSTR2/3/5-expressing synovial sarcoma and desmoplastic small round cell tumor: The PAMSARC study