Sarcoma Subtypes Research Articles

High expression level of ERBB2 and efficacy of trastuzumab deruxtecan in desmoplastic small round cell tumour: a monocentric case series report.

Desmoplastic small round cell tumours (DSRCTs) represent an ultra-rare subtype of soft tissue sarcoma characterized by a recurrent EWSR1::WT1 oncogenic translocation. Considered as an extremely aggressive cancer, the prognosis remains poor with a median overall survival not exceeding 24-36 months and a 5-year survival <10%. We analysed ERBB2/human epidermal growth factor receptor 2 (HER2) expression levels in aseries of 13 DSRCT patients, using whole-exome RNA sequencing on formalin-fixed paraffin-embedded samples from a local biopathological database. In addition, a retrospective case series describes the clinical outcome of three successive DSRCT patients treated with trastuzumab deruxtecan (T-DXd). The gene expression analysis demonstrated a consistent high RNA expression level of ERBB2 in DSRCT, with elevated levels [>5 log2(transcripts per million+ 1)] across all samples of the cohort and the expression level was the highest compared with all other sarcoma subtypes. In addition to these results, T-DXd showed a marked activity in all three DSRCT patients who presented with metastatic disease refractory to previous standard chemotherapy. So far, the treatment has been overall well tolerated and is currently pursued in the three patients (duration of response >3months for all three), which warrants additional investigation. This case series presents a major information, suggesting that HER2 is a therapeutic target in DSRCT and T-DXd might represent a novel therapeutic option. Those results require to be rapidly shared with the scientific community and confirmed in a prospective clinical trial in this context of very poor prognosis disease and urgent unmet need.

Myxoid liposarcoma: treatment outcomes, metastatic pattern and volumetric analysis.

Myxoid liposarcoma (MLPS) is arare subtype of soft tissue sarcoma. This entity has aspecific clinical behavior, characterized with adistinct pattern of hematogenous spread, as well as with aunique radiosensitivity and chemosensitivity. Oncologic results, metastatic patterns and treatment response after multimodal therapy were evaluated in aunicentric patient cohort. Patients with myxoid liposarcoma were retrospectively analyzed in asingle institution analysis (n = 31). Oncologic outcomes were evaluated in 28patients with localized MLPS treated with multimodal therapy in curative intent. Metastatic pattern was analyzed in additional 3patients with initially metastatic disease. In patients treated with concomitant MR-guided hyperthermia in the preoperative setting (n = 7), tumor size response was evaluated longitudinally during radio(-chemo)therapy in thermometry MRIs and before surgery (based on preoperative imaging). The median follow-up was 4.1 ± 1.0years. The most common anatomic localization was the lower extremity (78.6%). The 5‑year rates for oncologic outcomes in 28patients treated in curative intent were 91.7% (± 8.0%) for overall survival (OS), 77.4% (± 11.0%) for local control (LC), 60.1% (± 10.6%) for distant metastasis-free survival (DMFS) and 55.4% (± 11.1%) for disease free survival (DFS). Excellent 5‑year LC (94.7 ± 5.1%) was demonstrated for the cohort excluding 5patients treated for local recurrences. Most patients had good pathologic response (< 10% vital tumor tissue) following neoadjuvant treatment (82.4%, 14/17). However, this did not correlate with oncologic outcomes. Aspecific pattern of distant metastases has been observed, with predilection for soft tissues as the most common metastatic site. Furthermore, no isolated pulmonary metastases were observed. The MR analysis demonstrated asignificant tumor size reduction (≥ 25%) of the initial tumor volume in 85.7% (n = 6/7) patients. No local recurrences and no distant metastases were observed in patients with significant MR size reduction. Sequential MRIs during preoperative radiotherapy of myxoid liposarcoma show distinct patterns of the known size reduction of this specific subentity. Our analysis of metastatic patterns demonstrate mostly soft tissue metastases, no patient experienced isolated pulmonary metastases.

Transcriptomic and proteomic profiling identifies feline fibrosarcoma as clinically amenable model for aggressive sarcoma subtypes.

Fibrosarcomas (FSA) are malignant mesenchymal tumors characterized by low chemo- and radiosensitivity. Development of novel treatment strategies for human adult FSA is hindered by the low incidence and the absence of suitable clinical models. Interestingly, aggressive FSA occur more frequently in domestic cats, hence potentially representing a clinically amenable model to assess novel therapies such as targeted imaging or theranostics. However, a lack of molecular characterization of FSA and adjacent normal tissue (NT) in both species hinders identification of tumor-specific targets and undermines the translational potential of feline FSA. Combining laser-capture microdissection, RNAsequencing and liquid chromatography-tandem mass spectrometry, we perform comprehensive profiling of 30 feline FSA and matched skeletal muscle, adipose and connective tissue. Clear inter-tissue differences allow identification of significantly upregulated and tumor-exclusive features that represent potential targets for diagnostic and therapeutic approaches. While feline FSA are characterized by hyperactive EIF2, TP53 and MYC signaling, immune-related and neuronal pathways emerge as modulators of tumor aggressiveness and immunosuppression. A high degree of molecular similarity with canine and adult FSA allows identification of tumor targets that are conserved across species. Significant enrichment in DNA repair pathways in feline FSA correlate with aggressive clinical behavior in human soft-tissue sarcoma. Finally, we leverage the molecular profiles to identify vulnerabilities, including sensitivity to ATR and PARP inhibition as potential treatment for feline FSA. In conclusion, this detailed landscape provides a rich resource to identify target candidates and therapeutic vulnerabilities within and across species and supports feline FSA as relevant models for the human disease.

Dual inhibition of BET and EP300 has antitumor activity in undifferentiated pleomorphic sarcomas and synergizes with ferroptosis induction.

Undifferentiated pleomorphic sarcoma (UPS) is the most frequent and the most aggressive sarcoma subtype for which therapeutic options are limited. The identification of new therapeutic strategies is therefore an important medical need. Epigenetic modifiers has been extensively investigated in recent years leading to the development of novel therapeutic agents. Dual BET/EP300 inhibitors have shown synergistic antitumor activity and have recently entered clinical development. To date, no data related to potential of BET/EP300 inhibition as a treatment in UPS have been reported. To investigate the therapeutic potential of BET/EP300 inhibition, we evaluated the antitumor activity of three compounds in vitro via MTT, apoptosis and cell cycle assays. The most potent inhibitor was evaluated in vivo in two animal models and the mechanisms of action were investigated by RNA sequencing, Western blotting and immunofluorescence staining. A CRISPR knockout screen was performed to identify resistance mechanisms. Among the three compounds tested, the dual inhibitor NEO2734 was the most potent, decreased the viability of UPS cells in vitro through a regulation of E2F targets and cell cycle and decreased the tumor growth in vivo. Moreover, we identified GPX4 as a gene involved in resistance and showed synergy between BET inhibition and ferroptosis induction. The present study demonstrated that dual BET/EP300 inhibitors have a relevant antitumor activity in a subgroup of UPS characterized by expression of MYC-targets pathway and identified a potent combination therapeutic strategy that deserves further investigation in the clinical setting.

Subtype-Specific Patterns of Tumor Purity and Mutation Load Suggest Treatment Implications

Objectives: Sarcomas are complex mesenchymal malignancies whose molecular characteristics can significantly influence treatment strategies. This study aimed to investigate the relationship between tumor purity, mutation load, and clinical characteristics across sarcoma subtypes, focusing on potential implications for therapeutic stratification. Methods: This study analyzed the molecular characteristics of 7494 sarcoma cases from the Soft Tissue and Bone Sarcoma (MSK, Nat Commun 2022) data set using available case analysis. Correlations between tumor purity, mutation load, age, and sex were analyzed using nonparametric methods, with subtype-specific analyses conducted using Kruskal-Wallis tests and Bonferroni-corrected post hoc comparisons. A comprehensive analysis of mutation patterns was performed using microsatellite instability (MSI) status. Results: Significant correlations between mutation load and tumor purity (ρ=0.320, P&lt;0.001) were identified, with marked heterogeneity across subtypes. Tumor purity ranged from 20.0% in brain sarcomas to 78.5% in dermatofibrosarcoma protuberans. Age-related molecular changes were observed in brain (ρ=0.711, P=0.006) and skin sarcomas (ρ=0.450, P=0.006), suggesting distinct evolutionary patterns. A subset of hypermutated, microsatellite stable cases (0.15%) with mutation loads exceeding 100 mutations/mb were identified, suggesting alternative mechanisms of genomic instability. MSI-high status was rare (0.24%) but associated with higher mutation loads (median: 25.84 vs. 2.42, P&lt;0.001), particularly in uterine sarcomas (0.7% prevalence). Conclusions: The identification of distinct molecular patterns across sarcoma subtypes challenge existing morphology-based classification systems and may hold implications for therapeutic stratification. These findings may help inform future immunotherapeutic and molecular-guided approaches to treatment in sarcoma patients, particularly for elderly patients with brain sarcomas or females with uterine sarcomas.

Intratumoral oncolytic virus OH2 injection in patients with locally advanced or metastatic sarcoma: a phase 1/2 trial

BackgroundIntratumoral oncolytic herpes simplex virus 2-GM CSF (OH2) injection has shown safety and antitumor efficacy in patients with solid tumors. Here, we examined the safety and efficacy of OH2 as...

Genetic and epigenetic characterization of sarcoma stem cells across subtypes identifies EZH2 as a therapeutic target

High-grade soft tissue sarcomas (STS) are a heterogeneous and aggressive set of cancers. Failure to respond anthracycline chemotherapy, standard first-line treatment, is associated with poor outcomes. We investigated the contribution of STS cancer stem cells (STS-CSCs) to doxorubicin resistance. We identified a positive correlation between CSC abundance and doxorubicin IC50. Utilizing patient-derived samples from five sarcoma subtypes we investigated if a common genetic signature across STS-CSCs could be targeted. We identified Enhancer of Zeste homolog 2 (EZH2), a member of the polycomb repressive complex 2 (PRC2) responsible for H3K27 methylation as being enriched in CSCs. EZH2 activity and a shared epigenetic profile was observed across subtypes and targeting of EZH2 ablated the STS-CSC population. Treatment of doxorubicin-resistant cell lines with tazemetostat resulted in a decrease in the STS-CSC population. These data confirm the presence of shared genetic programs across distinct subtypes of CSC-STS that can be therapeutically targeted.

Incidence and survival of European adolescents and young adults diagnosed with sarcomas: EUROCARE-6 results.

Epidemiological data for sarcoma in adolescents and young adults (AYAs) and across age groups are limited. We aim to: 1) update sarcoma incidence, survival, and changes over time in European AYAs; 2) provide an updated comparison of sarcoma survival in AYAs versus children and mature adults. We calculated crude incidence rates (IR) per 100,000 European population per year from 2006 to 2013. Using the period approach, we calculated 5-year relative survival (RS) for the follow-up period 2010-2014. We estimated changes in incidence and survival for bone sarcoma (BS) and soft tissue sarcoma (STS) subtypes in AYAs in the years 2000-2013. In European AYAs, the IR was 0.81/100,000 for BS and 1.45/100,000 for STS. Five-year RS was 69 % and 65 % for BS and STS, respectively. Compared to children, AYAs had poorer survival for Ewing sarcoma of bone, synovial sarcoma, Ewing sarcoma of soft tissue and rhabdomyosarcoma. Compared to mature adults, AYAs had higher 5-year RS for all BS and for most of the STS subtypes. In AYAs, incidence increased for a few bone and soft tissue subtypes. Survival increased mainly for BS. The reason for the better survival observed in AYAs compared to mature adults is probably multifactorial. The limited improvement of STS survival in AYAs may reflect the relative absence of new drugs for STS during the study period. The increase in RS for BS might relate to general improvements in radiological and surgical approaches and radiotherapy techniques.

Oncogenic Functions of Alternatively Spliced MDM2-ALT2 Isoform in Retroperitoneal Liposarcoma.

Retroperitoneal liposarcoma (RPLPS) is one of the most common histologic subtypes of soft tissue sarcoma (STS). Complete surgical resection remains the mainstay treatment, while the high rate of locoregional recurrence constitutes the predominant cause of mortality. Well-differentiated (WDLPS) and dedifferentiated (DDLPS) liposarcoma are the most frequent subtypes of RPLPS and present amplified MDM2 gene as a hallmark. However, there are few reports evaluating the role of alternatively spliced MDM2 transcripts in RPLPS. In this study, we assessed MDM2-ALT2 expression levels in a cohort of RPLPS patients and evaluated the biological functions of the MDM2-ALT2 isoform in vitro in DDLPS cell lines. Using BaseScope™ and qPCR, we demonstrated that MDM2-Full Length (MDM2-FL) and MDM2-ALT2 expression levels were upregulated in RPLPS patient-derived tissue samples compared to normal adjacent to tumor tissue (NAT). DDLPS cells overexpressing MDM2-FL or MDM2-ALT2 had higher proliferation rates and increased migration and invasion capacities, as well as increased protein levels of p-AKT, mTOR, p70S6K, MMP2, and cJun. Simultaneous overexpression of MDM2-ALT2 and AKT silencing showed that AKT inhibition impaired p-p70S6K and MMP2 protein increased levels and led to significantly decreased proliferation and migration rates compared to cells overexpressing MDM2-ALT2 only. Taken together, our data suggest that MDM2-ALT2 may promote RPLPS progression.

Comprehensive study of gene fusions in sarcomas.

Sarcomas, including bone sarcomas and soft tissue sarcomas (STSs), are a heterogeneous group of mesenchymal malignancies. Recent advancements in next-generation sequencing (NGS) have enabled the identification of novel chromosomal translocations and fusion genes, which play a critical role in sarcoma subtypes. Our study focuses on gene fusions in sarcomas among Chinese patients, comparing their genomic profiles to those of Western populations. We analyzed 1048 sarcoma samples from Chinese patients using a panel of over 500 genes, identifying 481 gene fusions in 329 patients. The most common fusions included EWSR1, HMGA2, and SS18, with notable subtype-specific fusions such as EWSR1-FLI1 in Ewing sarcoma and NAB2-STAT6 in solitary fibrous tumors. In comparison to Chinese and Western populations, variations in fusion spectrum exist, potentially necessitating distinct treatment strategies; however, further validation of these fusions is warranted. Our findings highlight the importance of gene fusions as diagnostic markers and potential therapeutic targets. Actionable fusions, including kinase-related fusions like ALK, NTRK3, and BRAF, were detected in 67 patients (6.4%) and may guide precision therapies. Additionally, we observed the frequent co-occurrence of genomic alterations, particularly in cell cycle regulators such as CDK4 and MDM2. Genomic profiling of sarcomas offers valuable insights into their molecular drivers and can support personalized therapeutic approaches. Further research is needed to validate these findings and optimize treatment strategies for sarcoma patients.

NR1D1exon6::MAML2exon2 Fusion-Positive Sarcomas: Two Additional Cases of an Emerging Soft Tissue Tumor Entity.

NR1D1::MAML1/L2 fusion-positive sarcomas constitute an emerging subtype of undifferentiated sarcomas, histopathologically composed of epithelioid and spindle cells. We describe two NR1D1exon6::MAML2exon2 fusion-positive sarcomas occurring in the occipital region of a 53-year-old female patient and the left shoulder of a 25-year-old male patient. Histopathologically, the former tumor comprised spindle and polygonal-shaped/epithelioid cells, while the latter comprised epithelioid cells. Immunohistochemically, the cells of the first tumor were positive for keratin cocktail (AE1/AE3), EMA, and p40. The other tumor lacked any epithelial marker immunoexpression and showed SATB2 positivity. Both the tumors were SMARCB1 proficient. While the former tumor was initially diagnosed as a sarcomatoid carcinoma, the latter was diagnosed as an undifferentiated sarcoma.Both patients underwent surgical resection as the primary treatment. One patient received adjuvant radiotherapy, whereas the other received ifosfamide and doxorubicin-based therapy. However, both the patients developed progressive disease, with one developing lung metastasis during relapse. There was a suboptimal response to chemotherapy in both patients.This study highlights the clinicopathological features of two rare and emerging sarcomas. It further emphasizes the value of high-throughput molecular testing, such as next-generation sequencing in the undifferentiated epithelioid, and spindle-cell sarcomas to identify the prognostic subtypes and differentiate these neoplasms from their histopathological mimics.

Contemporary Trends in Reconstruction for Patients With Sarcoma of the Breast.

Breast sarcomas are rare, heterogeneous malignancies often associated with prior radiation and require a multidisciplinary approach, including a comprehensive reconstruction plan. We analyzed reconstructive outcomes in a large cohort of patients with breast sarcomas and provide a contemporary treatment algorithm. We retrospectively reviewed patients who underwent breast reconstruction after surgical treatment for breast sarcoma at our institution between January 2010 and December 2023. We analyzed patient and tumor characteristics, oncologic treatments, reconstructive approaches, and outcomes. Eighty patients underwent 81 reconstructions. The median age at diagnosis was 53 years. The most common subtypes were primary angiosarcoma (35.8%) and radiation-associated angiosarcoma (33.3%). The median follow-up was 23 months. Oncologic management was multimodal: 63.0% received preoperative chemotherapy, 59.3% received post-operative chemotherapy, 35.8% received both pre- and post-operative chemotherapy, and 34.6% received pre- or post-operative radiation therapy. Forty-three (53.1%) patients underwent total mastectomy with or without chest wall resection requiring soft-tissue reconstruction. Thirty-eight (46.9%) patients underwent formal breast reconstruction. Autologous reconstructions included local tissue rearrangement (39.5%), pedicled flaps (18.5%), regional flaps (16.0%), and free flaps (13.6%). Most patients (82.7%) underwent immediate reconstruction. Breast sarcomas are managed with multimodal therapy, and most patients undergo immediate reconstruction. Autologous reconstruction remains the first choice in radiated patients, however implant-based reconstruction has increased with modern approaches. Complication rates are acceptable and similar across sarcoma subtypes. Breast reconstruction is an essential component of care for these patients and can be performed safely and with good results.

YAP1::KMT2A-rearranged sarcomas harbor a unique methylation profile and are distinct from sclerosing epithelioid fibrosarcoma and low-grade fibromyxoid sarcoma.

Sclerosing epithelioid fibrosarcoma (SEF) was originally described as a peculiar variant of fibrosarcoma in 1995. Subsequent studies showed that conventional SEF was associated with both immunohistochemical expression of MUC4 and EWSR1/FUS gene rearrangements with CREB3L1 as the predominant fusion partner. Since then, a distinct group of fibrous tumors characterized by YAP1::KMT2A and KMT2A::YAP1 gene rearrangements and SEF-like morphology has been described. These YAP1::KMT2A-rearranged sarcomas were further shown to lack both immunohistochemical expression of MUC4 and canonical EWSR1/FUS gene rearrangements. To better understand whether the YAP1::KMT2A-rearranged sarcomas represent a subset of MUC4-negative SEF or a distinct entity, we studied 22 cases of YAP1::KMT2A-rearranged sarcomas, the largest series to date, and performed a literature review of all previously reported next-generation sequencing (NGS)-confirmed cases. These sarcomas often arose in young adults with a median age of 38 years and a male to female (M:F) ratio of 1.4:1. They predominantly involved somatic soft tissue; however, we report the first case of a tumor that primarily developed inside bone. Immunohistochemical studies showed that the tumors often demonstrated expression of YAP1 and EMA, while all tested cases were negative for MUC4. NGS confirmed the presence of YAP1::KMT2A gene fusions in all cases, some of which initially had false negative results with targeted FISH and solid tumor panel testing. Clinical follow-up information was available in 14 patients with a median follow-up of 25 months (range 1 to 170 months). Local recurrence occurred in three patients (21%) and metastasis developed in seven patients (50%). DNA methylation analysis further showed that YAP1::KMT2A-rearranged sarcomas formed a distinct cluster, which was clearly separate from both conventional SEF and low-grade fibromyxoid sarcoma (LGFMS). These results suggest that YAP1::KMT2A-rearranged sarcomas likely represent a unique sarcoma subtype with propensity for aggressive behavior.

Descriptive analysis of incidence, demographic characteristics, and survival outcomes of soft-tissue sarcoma of the extremities in Saudi Arabia

Soft-tissue sarcomas are uncommon, aggressive, and histologically heterogeneous, malignant tumors. Soft-tissue tumor types have different age and anatomical site distributions. This study aimed to assess the prevalence and incidence of soft-tissue sarcomas of the extremities to facilitate early diagnosis and intervention in the Kingdom of Saudi Arabia. This retrospective study included all patients diagnosed with primary soft-tissue sarcomas of the extremities and pelvis between January 2006 and December 2015. The data were obtained from the Saudi Cancer Registry. Means and confidence intervals were reported for numerical variables, whereas the frequencies and percentages were reported for categorical variables. The chi-squared test and analysis of variance were used to test the associations between categorical numerical variables. Cox regression analysis was used to determine the hazard ratios for each sarcoma type. Of the 659 patients, 145 (22%) were aged 19–30 years, 365 (55.4%) were men, and 411 (62.4%) had lower limb sarcoma. Most of the tumors (54.3%) were localized. The incidence of sarcoma ranged from 2 to 2.9 cases per one million (average, 2.4 cases per one million). Moreover, liposarcoma was the most commonly diagnosed (n = 135; 20.5%), followed by undifferentiated pleomorphic sarcoma (n = 87; 13.2%). The incidence of soft-tissue sarcomas in the Kingdom of Saudi Arabia were lower than those in Western countries. However, the distribution of soft-tissue sarcoma subtypes was similar to those in other countries. The survival rates in this study highlight the need for continued research and targeted interventions to improve the outcomes of patients with soft-tissue sarcomas, especially those with more aggressive subtypes, such as sarcoma not otherwise specified and rhabdomyosarcoma.

Abstract A054: Oncogenic functions of alternatively spliced MDM2-ALT2 isoform in retroperitoneal liposarcoma

Abstract Retroperitoneal liposarcoma (RPLPS) is one of the most common histologic subtypes of soft tissue sarcoma (STS). Complete surgical resection remains the mainstay treatment while the high rate of locoregional recurrence constitutes the predominant cause of mortality. Well- differentiated (WDLPS) and dedifferentiated (DDLPS) liposarcoma are the most frequent subtypes of RPLPS and present amplified MDM2 gene as a hallmark. However, there are few reports evaluating the role of alternatively spliced MDM2 transcripts in RPLPS. In this study, we assessed MDM2-ALT2 expression levels in a cohort of RPLPS patients and evaluated biological functions of MDM2-ALT2 isoform in vitro in DDLPS cell lines. Using BaseScope™ and qPCR, we demonstrated that MDM2-Full Length (MDM2-FL) and MDM2-ALT2 expression levels were upregulated in RPLPS patient-derived tissue samples compared to normal adjacent to tumor tissue (NAT). DDLPS cells overexpressing MDM2-FL or MDM2-ALT2 had higher proliferation rates and increased migration and invasion capacities, as well as increased protein levels of p- AKT, mTOR, p70S6K, MMP2 and cJun. Simultaneous overexpression of MDM2-ALT2 and AKT silencing showed that AKT inhibition impaired p-p70S6K and MMP2 protein increased levels and led to significantly decreased proliferation and migration rates compared to cells overexpressing MDM2-ALT2 only. Taken together, our data suggest that MDM2-ALT2 may promote RPLPS progression. Citation Format: Fernanda Costas C. de Faria, Safiya Khurshid, Patricia Sarchet, Sayumi Tahara, Lucia Casadei, Valerie Grignol, Roma Karna, Sydney Rentsch, Nippin Sp, Joal D Beane, Luciano Mazzoccoli, Matias Montes, Giovanni Nigita, Joe T Sharick, Jennifer L Leigth, Federica Calore, Dawn Chandler, Raphael E Pollock. Oncogenic functions of alternatively spliced MDM2-ALT2 isoform in retroperitoneal liposarcoma [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr A054.

Abstract 4136692: Spatial Transcriptomics Identifies Novel Clinical Markers to Classify the Etiology of Rare and Aggressive Cardiac Sarcomas

Background: Cardiac sarcomas, such as leiomyosarcoma (LMS), synovial sarcoma (SS), and undifferentiated pleomorphic sarcoma (UPS), lack sufficient diagnostic markers for early diagnosis and tailored therapeutic interventions. Understanding their molecular signatures with spatial-temporal resolution compared to normal heart tissue is crucial. Hypothesis: Spatial transcriptomics will reveal a comprehensive set of novel clinical markers, including changes in cellular composition, stemness, and metabolic profiles unique for each cardiac sarcoma subtypes. Aims: Identify novel molecular markers for the accurate diagnosis of cardiac sarcoma subtypes. Methods: Using 10X Visium spatial transcriptomics, we analyzed three cardiac sarcoma subtypes (LMS, SS, UPS) and compared them with normal heart tissue. Differential expression analysis identified novel target genes suitable for clinical disease stratification. Subsequently, machine learning models reveal an unbiased transcriptomic profile to distinguish normal from sarcoma tissues. Finally, immunohistochemistry analysis validated the differential marker gene expression. Results: We identify several novel clinical markers, such as IGKC, PCOLCE, NET1, TLE2, MDFI, BGN, TNNC1, and CNN3, that classify normal heart tissue from sarcoma subtypes. Machine learning models and immunostaining analysis confirm the transcriptomic signature in each sarcoma subtype. Pathway enrichment analysis show LMS enriched in antigen processing and B cell-mediated immunity, SS in protein folding and response to incorrect proteins, and UPS in axon development and Wnt signaling regulation. Trajectory Reconstruction Analysis indicate higher stemness scores in all sarcomas, with SS highest, followed by UPS and LMS. Additional cell cycling analysis show LMS cells in G2M phase, SS in G1, and UPS in S phase. SS express a high number of cancer stem markers (EZH2, BMI1, KDM5B, LGR5, HIF1A), while UPS express KDM5B and CTNNB1, and LMS show fewer stem-related marker genes (EZH2, BMI1, KDM5B, CTNNB1). Both SS and LMS express CD44. Glucose and oxidative pathways are also differentially regulated in each sarcoma subtype. Conclusion: Spatial transcriptomics uncovers distinct clinical markers, stemness characteristics, and metabolic activity profiles in cardiac sarcomas, offering insights for fast, accurate and improved diagnostics and therapeutics.

Dysregulation of miRNAs in Soft Tissue Sarcomas.

MicroRNAs (miRNAs) are pivotal regulators of gene expression, influencing key cellular processes such as proliferation, differentiation, apoptosis, and metastasis. In the realm of sarcomas-a diverse group of malignant tumors affecting soft tissues and bone sarcomas-miRNAs have emerged as crucial players in tumorigenesis and tumor progression. This review delves into the intricate roles of miRNAs across various soft tissue sarcoma subtypes, including rhabdomyosarcoma, liposarcoma, leiomyosarcoma, synovial sarcoma, fibrosarcoma, angiosarcoma, undifferentiated pleomorphic sarcoma (UPS), and malignant peripheral nerve sheath tumor (MPNST). We explore how dysregulated miRNAs function as oncogenes or tumor suppressors, modulating critical pathways that define the aggressive nature of these cancers. Furthermore, we discuss the diagnostic and prognostic potential of specific miRNAs and highlight their promise as therapeutic targets. By understanding the miRNA-mediated regulatory networks, this review aims to provide a comprehensive overview of current research while pointing towards future directions for miRNA-based therapies. Our findings underscore the potential of miRNAs to transform the landscape of sarcoma treatment, offering hope for more precise, personalized, and effective therapeutic strategies.

Transcriptomic profiles of myxofibrosarcoma and undifferentiated pleomorphic sarcoma correlate with clinical and genomic features.

Myxofibrosarcoma (MFS) and undifferentiated pleomorphic sarcoma (UPS) are two common and aggressive subtypes of soft tissue sarcoma. The aim of this study was to assess potential transcriptomic differences between MFS and UPS tumours and to evaluate the extent to which differences in gene expression profiles were associated with genomic and clinical features. The study included 162 patients with tumours diagnosed as MFS (N = 62) or UPS (N = 100). The patients had been diagnosed and treated at two Swedish sarcoma centres during a 30-year period. For gene expression profiling and gene fusion detection all tumours were analysed using RNA-sequencing and could be compared with data on clinical outcome (N = 155), global copy number profiles (N = 145), and gene mutations (N = 128). Gene expression profiling revealed three transcriptomic clusters (TCs) without any clear separation of MFS and UPS. One TC was associated with longer metastasis-free survival. These tumours had lower tumour mutation burden (TMB), were enriched for a copy number signature representative of focal LOH and chromosomal instability on a diploid background, and were relatively immune-depleted. MFS and UPS showed extensive genomic overlap, with whole genome doubling occurring more frequently among the latter. The results support the idea that MFS and UPS tumours have largely overlapping genomic and transcriptomic features, with UPS tumours showing more aggressive behaviour and more complex genomes. Independently of the tumour type, clinically relevant subgroups were revealed by gene expression analysis, and the finding of multiple genomic subgroups strongly suggest the existence of subgroups of relevance to treatment stratification. © 2024 The Author(s). The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

B7-H3 is widely expressed in soft tissue sarcomas

PurposeTargeted therapy development in soft tissue sarcoma (STS) has been burdened by the heterogeneity of this group of rare tumors. B7 homolog 3 protein (B7-H3) is a molecule in the same family as programmed death-ligand 1 (PD-L1). It has limited expression in noncancerous tissues and is overexpressed in many cancers, making it an attractive target for cancer therapy, and clinical trials targeting B7-H3 are actively underway. While available data demonstrate high expression levels of B7-H3 in individual sarcoma subtypes, its expression patterns across STS subtypes are not well described. The purpose of this study was to characterize the expression patterns of B7-H3 in STS.Patients and methodsThis retrospective analysis evaluated STS tumor specimens from patients with a variety of different subtypes. Specimens were evaluated by immunohistochemistry (IHC) for expression and staining pattern of B7-H3 both in tumors and in associated vasculature.ResultsSpecimens from 153 sarcoma patients included 15 different STS subtypes. B7-H3 was broadly expressed in 97% of samples (95% CI 0.93–0.99) and 69.2% demonstrated high levels of B7-H3 expression (95% CI 0.61–0.76). No significant association between B7-H3 positivity or expression level and prior treatment(s), tumor size, tumor grade, or patient age. B7-H3 positivity in vessels was found in 94.7% (145/153) of samples. In tumors that had been previously assessed for PD-L1 and PD-1, there was no correlation between B7-H3 positivity or expression and the positivity or expression level of PD-L1 or PD-1.ConclusionThese data show high levels of B7-H3 positivity across soft tissue sarcoma subtypes, suggesting its feasibility as a therapeutic target for future sarcoma treatments. Future clinical trials are needed to evaluate whether targeting B7-H3 can provide clinical benefit to help patients with sarcoma.

Histology-Specific Clinical Trial of Lenvatinib and Pembrolizumab in Patients with Sarcoma.

Survival of patients with metastatic sarcoma remains poor, and there is a pressing need for new therapies. Most sarcoma subtypes are not responsive to immune checkpoint inhibition alone. Lenvatinib, a multireceptor tyrosine kinase inhibitor targeting tumor vasculature, has an immunomodulatory activity that contributes to its antitumor effects. Therefore, we hypothesized that a combination of lenvatinib and pembrolizumab would lead to improved clinical outcomes in patients with sarcoma. This was an open-label, single-arm study of lenvatinib and pembrolizumab in the following cohorts: (A) leiomyosarcoma, (B) undifferentiated pleomorphic sarcoma (UPS), (C) vascular sarcomas (angiosarcoma and epithelioid hemangioendothelioma), (D) synovial sarcoma or malignant peripheral nerve sheath tumor (MPNST), and (E) bone sarcomas (osteosarcoma and chondrosarcoma). The primary endpoint was the best overall response (BOR) rate documented by RECIST v1.1 by 27 weeks in each cohort, with a threshold of ≥2 responses among 10 patients. Secondary endpoints included progression-free survival, overall survival, duration of response, and safety. Forty-six patients were evaluable for the primary endpoint, which was met in the UPS and MPNST/synovial cohorts (BOR rates by 27 weeks of 25% and 30%, respectively). There were seven partial responses overall with additional responses noted in angiosarcoma and osteosarcoma. Treatment-related adverse events of any grade and grade 3 or higher occurred in 50/51 (98%) and 29/51 (57%) of patients, respectively. We observed durable responses in MPNST, synovial sarcoma, and osteosarcoma. Patients with UPS and angiosarcoma also responded. Further exploration of this approach is warranted to confirm activity and determine optimal dosing schedules.