Desmoplastic Small Round Cell Tumor Research Articles

Mesenchymal tumours of the pleura: review and update.

Primary mesenchymal tumours of the pleura are uncommon and can be diagnostically challenging due to their overlapping histopathologic and immunophenotypic features. Herein we discuss selected mesenchymal tumours of the pleura, including solitary fibrous tumour, calcifying fibrous tumour, desmoid fibromatosis, synovial sarcoma, schwannoma, malignant peripheral nerve sheath tumour, inflammatory myofibroblastic tumour, follicular dendritic cell sarcoma, epithelioid hemangioendothelioma, and desmoplastic small round cell tumour. We review their clinicopathologic characteristics, along with an update on the relevant immunohistochemical and molecular features.

Desmoplastic Small Round Cell Tumor: Study of Cytomorphologic and Immunophenotypical Features in Eight Cases, One with Usual Rhabdoid Morphology

Desmoplastic Small Round Cell Tumor: Study of Cytomorphologic and Immunophenotypical Features in Eight Cases, One with Usual Rhabdoid Morphology

Desmoplastic small round cell tumor of the liver: diagnosing a rare case on liver biopsy

Desmoplastic small round-cell tumors (DSRCT) frequently develop in the retroperitoneum, pelvis, omentum, and mesentery. Here, we present an unusual case of primary DSRCT in the liver. The patient was an 11-year-old boy with multiple solid masses in the liver parenchyma. The tumor in the needle biopsy had a histology revealing a small round cell morphology and desmoplasia. It shows the immunohistochemical features of DSRCT and documentation of EWSR1-WT1 fusion.A potential diagnostic pitfall is exerted when evaluating liver biopsy, in which DSRCT is a great mimicker and may be easily confused with more common liver malignancies of childhood, such as hepatoblastoma, calcifying nested stromal-epithelial tumor, undifferentiated embryonal sarcoma, and other small round cell tumors, as well as the fibrolamellar variant of hepatocellular carcinoma. This distinction is critical because an accurate therapeutic approach requires a correct diagnosis.

Desmoplastic small round cell tumor of the pleura with brain metastasis: A case report and literature review

Introduction: Desmoplastic small round cell tumor (DSRCT) is a rare and aggressive mesenchymal neoplasm characterized by a chromosomal translocation involving the EWSR1 and WT1 genes. It typically arises in intra-abdominal tissues (i.e., mesentery, omentum, pelvic organs), and commonly spreads to regional lymph nodes, lungs, or liver, while central nervous system (CNS) metastasis is rare. Case Report: We present a unique case of DSRCT originating from the pleura in a young female, which was metastatic to intrathoracic and mediastinal tissue at diagnosis and later spread to the brain. The initial tumor samples exhibited characteristic histopathological features, including small round cells with minimal cytoplasm and indistinct borders embedded in a fibroblastic stroma. Notably, the brain metastasis demonstrated distinct histological characteristics, lacking the desmoplastic stroma observed in previous biopsies. Conclusion: This case underscores the diagnostic challenges associated with DSRCT, emphasizes the significance of early recognition and appropriate histological evaluation, and contributes to the limited literature on the histological features and metastatic behavior of this rare tumor.

Rare tumors: Opportunities and challenges from the Children’s Oncology Group perspective

While all childhood cancers are rare, tumors that are particularly infrequent or underrepresented within pediatrics are studied under the umbrella of the Children’s Oncology Group Rare Tumor committee, divided into the Retinoblastoma and Infrequent Tumor subcommittees. The Infrequent Tumor subcommittee has traditionally included an emphasis on globally rare tumors such as adrenocortical carcinoma, nasopharyngeal carcinoma, or those tumors that are rare in young children, despite being common in adolescents and young adults, such as colorectal carcinoma, thyroid carcinoma, and melanoma. Pleuropulmonary blastoma, gonadal stromal tumors, pancreatic tumors including pancreatoblastoma, gastrointestinal stromal tumor, nonmelanoma skin cancers, neuroendocrine tumors, and desmoplastic small round cell tumors, as well as other carcinomas are also included under the heading of the Children’s Oncology Group Rare Tumor committee. While substantial challenges exist in rare cancers, inclusion and global collaboration remain key priorities to ensure high quality research to advance care.

Progression and Relapse of Pediatric Soft Tissue Sarcoma: Individualized Approach of Treatment - Experience from a Major Pediatric Cancer Center in Europe.

The outcome of children with refractory or relapsed soft tissue sarcoma (STS) is extremely poor. Whereas larger clinical trials evaluated specific treatment modalities, real-life data on individual multimodal therapeutic strategies, given alone or in combination, are scarce. We retrospectively analyzed the clinical course of 18 pediatric patients with progression of or relapsed STS treated between 2008 and 2018 in our institution. A total of 18 patients (median age 12.4 years) suffered from progression or relapse of alveolar (n=7), embryonal (n=5), undifferentiated (n=2) rhabdomyosarcoma or desmoplastic small round cell tumor (n=4). 14 patents had an initial stage IV disease. All but one patient died. Median survival was 12.5 months. Shortest survival was seen in patients with systemic progression of the disease, longest in patients with local relapse. Patients with an Oberlin score<2 at the time of relapse had a significant longer time of survival than those with a score≥2. No significant advantage of a specific therapeutic modality was observed. We critically analyzed the clinical course in the real-life setting, in which various treatment options were applied to an individual patient according to the best of available data. We observed that some patients died within a short period of time despite multiple treatment modalities, which underlines the need for better prognostic parameters. In addition to well characterized clinical factors such as local or systemic relapse, the Oberlin score could be helpful in counselling patients and their families for choosing the best strategy of care.

Pembrolizumab in patients with rare and ultra-rare sarcomas (AcSé Pembrolizumab): analysis of a subgroup from a non-randomised, open-label, phase 2, basket trial

Sarcoma is a heterogeneous group of diseases with few treatment options. Immunotherapy has shown little activity in studies including unselected sarcomas, but immune checkpoint blockers have shown activity in specific histotypes. We evaluated the activity of pembrolizumab in rare and ultra-rare sarcomas. AcSé Pembrolizumab is an ongoing phase 2, basket, multitumour study investigating the activity of pembrolizumab monotherapy in rare cancers. Here, we report the results obtained in patients with selected histotypes of rare sarcomas (incidence of less than one case per 1 000 000 people per year) recruited at 24 French hospitals. Key inclusion criteria were age 15 years or older, Eastern Cooperative Oncology Group performance status of 0-1, and advanced disease that was untreated and resistant to treatment. Patients were given pembrolizumab 200 mg intravenously on day 1 of every 21-day cycle for a maximum of 24 months. The primary endpoint was objective response rate at week 12 using Response Evaluation Criteria in Solid Tumours version 1.1, assessed by local investigators. The primary endpoint and safety were analysed in the intention-to-treat population. The AcSé Pembrolizumab study is registered with ClinicalTrials.gov, NCT03012620. Between Sept 4, 2017, and Dec 29, 2020, 98 patients were enrolled, of whom 97 received treatment and were included in analyses (median age 51 years [IQR 35-65]; 53 [55%] were male; 44 [45%] were female; no data were collected on race or ethnicity). 34 (35%) patients had chordomas, 14 (14%) had alveolar soft part sarcomas, 12 (12%) had SMARCA4-deficient sarcomas or malignant rhabdoid tumours, eight (8%) had desmoplastic small round cell tumours, six (6%) had epithelioid sarcomas, four (4%) had dendritic cell sarcomas, three (3%) each had clear cell sarcomas, solitary fibrous tumours, and myxoid liposarcomas, and ten (10%) had other ultra-rare histotypes. As of data cutoff (April 11, 2022), median follow-up was 13·1 months (range 0·1-52·8; IQR 4·3-19·7). At week 12, objective response rate was 6·2% (95% CI 2·3-13·0), with no complete responses and six partial responses in the 97 patients. The most common grade 3-4 adverse events were anaemia (eight [8%] of 97), alanine aminotransferase and aspartate aminotransferase increase (six [6%]), and dyspnoea (five [5%]). 86 serious adverse events were reported in 37 patients. Five deaths due to adverse events were reported, none of which were determined to be related to treatment (two due to disease progression, two due to cancer, and one due to unknown cause). Our data show the activity and manageable toxicity of pembrolizumab in some rare and ultra-rare sarcoma histotypes, and support the PD-1/PD-L1 pathway as a potential therapeutic target in selected histotypes. The completion of the basket study will provide further evidence regarding the activity and toxicity of pembrolizumab in identified rare types of cancer. The Ligue contre le cancer, INCa, MSD. For the French translation of the abstract see Supplementary Materials section.

Desmoplastic Small Round Cell Tumors- Case series of a Rare Tumor and Review of Literature

Desmoplastic small round cell tumor (DSRCT) is an uncommon and aggressive malignancy with male predominance. It commonly occurs in the abdominal cavity and is usually diagnosed with help of histopathology. It shows a characteristic EWSR1-WT1 gene fusion in most cases. We hereby report a series of 3 cases of DSRCT that we encountered at our institute. All of them presented in an advanced stage as quoted in the previously available literature. The ideal treatment should include a multidisciplinary team. The chemotherapy regimen used is usually Ewing’s sarcoma protocol of multiagent chemotherapy. Surgical approaches which include cytoreduction and intra-peritoneal hyperthermic chemotherapy are the procedure of choice but rarely feasible. Newer clinical trials of targeted therapy are in progress for improving the treatment and thereby the prognosis of DSRCT.

Desmoplastic small round cell tumor: the report of two cases and literature analysis review of the radiological findings.

Desmoplastic small round cell tumor: the report of two cases and literature analysis review of the radiological findings.

CXCR4-Directed Imaging and Endoradiotherapy in Desmoplastic Small Round Cell Tumors.

Desmoplastic small round cell tumor (DSRCT) is a rare, radiosensitive, yet difficult-to-treat sarcoma subtype affecting predominantly male adolescents. Extensive intraperitoneal seeding is common and requires multimodal management. With no standard therapy established, the prognosis remains poor, and new treatment options are needed. We demonstrate the clinical potential of C-X-C motif chemokine receptor 4 (CXCR4)-directed imaging and endoradiotherapy in DSRCT. Methods: Eight male patients underwent dual-tracer imaging with [18F]FDG and CXCR4-directed [68Ga]pentixafor PET/CT. A visual comparison of both tracers, along with uptake quantification in active DSRCT lesions, was performed. [68Ga]pentixafor uptake was correlated with immunohistochemical CXCR4 expression on tumor cells. Four patients with end-stage progressive disease underwent CXCR4-based endoradiotherapy. We report the safety, response by RECIST 1.1, and survival after endoradiotherapy. Results: Uptake of [68Ga]pentixafor in tumor lesions was demonstrated in all patients with DSRCT, providing diagnostic power comparable to [18F]FDG PET. Corresponding CXCR4 expression was confirmed by immunohistochemistry in all DSRCT biopsies. Finally, 4 patients were treated with CXCR4-directed [90Y]endoradiotherapy, 3 in a myeloablative dose range with subsequent autologous stem cell transplantation. All 3 required transfusions, and febrile neutropenia occurred in 2 patients (resulting in 1 death). Notably, severe nonhematologic adverse events were absent. We observed signs of response in all 3 patients, translating into disease stabilization in 2 patients for 143 and 176 d, respectively. In the third patient, postmortem autopsy confirmed a partial pathologic response. Conclusion: We validated CXCR4 as a diagnostic biomarker and a promising target for endoradiotherapy in DSRCT, demonstrated its feasibility, and provided the first evidence of its clinical efficacy.

Desmoplastic Small Round Cell Tumor Involving Serous Fluid: Cytologic Features and Diagnostic Pitfalls: A Series of 8 Cases.

When desmoplastic small round cell tumor (DSRCT) is present in serous fluid, the cytomorphology can be diverse and can mimic metastatic carcinomas and thus present a diagnostic challenge. The aim of this study was to evaluate the cytomorphologic and immunocytochemical features of this rare tumor in serous effusion specimens. Demographic, clinical, radiologic, and pathologic information from patients who had a DSRCT diagnosis on body fluid specimens was collected and cytologic slides were reviewed. Nine specimens were identified (5 pleural fluid and 4 ascitic fluid specimens) from 8 patients (5 male and 3 female). The mean patient age at diagnosis was 26 years. The most common symptoms were abdominal distension and pain, with 5 patients having abdominal masses. Other findings included peritoneal carcinomatosis, liver masses, ascites, and pleural nodules. The predominant cytomorphology was loose cellular clusters, followed by tight clusters of small cells with scant occasional vacuolated cytoplasm and a sphere-like pattern. Serous fluid may be the first available specimen to diagnose DSRCT. In young patients with no history of malignancy and radiologic finding of peritoneal implants, DSRCT should be considered a possibility in the differential diagnosis, and sensitive markers should be used for accurate diagnosis.

Abstract A082: The epigenetic impact and therapeutic opportunity of AR-directed therapy for desmoplastic small round cell tumor

Abstract Desmoplastic small round cell tumor (DSRCT) is a rare, usually incurable, aggressive sarcoma subtype that occurs predominantly in adolescent and young adult (AYA) males. At diagnosis, most present with hundreds of intraabdominal nodules composed of malignant cells that harbor a EWSR1-WT1 chromosomal translocation and resultant fusion protein (FP). It was shown that a subset of DSRCT cells (mostly of epithelial histotype) highly express the androgen receptor (AR), a key epigenetic driver of prostate cancer (PC). Given the male predilection and the high expression of AR, we sought to assess the role of AR more comprehensively in DSRCT and ask if this tumor shared AR resistance mechanism to PC. We tested if AR antagonists curb cell proliferation and tumor growth, where both enzalutamide and AR-antisense therapy blocked DHT-induced cell proliferation and reduced xenograft tumor burden. Next, to mechanistically interrogate AR’s oncogenic effects, we performed single-nuclei RNA-seq (snRNA-eq) and chromatin immunoprecipitation sequencing (ChIP-seq) on frozen patient specimens. Those studies revealed a surprising epigenetic similarity between DSRCT to PC. Though overlap exists in the DNA binding MOTIFs of AR in DSRCT and PC, our ChIP-seq resultsrevealed DSRCT-specific AR DNA binding sites adjacent to key oncogenic regulators, including FOXF1 and WT1 (the C-terminal partner of the pathognomonic FP). To our surprise, we identified a subset of DSRCT samples that underwent partial neuroendocrine (NE) epigenetic reprogramming, akin to what occurs in ~1/3 of castrate-resistant PC (CRPC). Since androgen deprivation therapy (ADT) isn’t yet a standard treatment for DSRCT, it remains an enigma why DSRCT would undergo NE reprogramming or how this may affect ADT sensitivity. To address this, nine DSRCT patient samples were profiled using snRNA-seq. Sub-clustering revealed epithelial, mesenchymal, or NE signatures and marked inter-patient and intra-tumoral heterogeneity. Notably, five of nine patients exhibited NE markers (SYP, ENO2, CHGA, FOXA2, ASCL1, and SOX2), while three expressed epithelial markers (MUC1, MUC6, KRT18, KRT23, CDH1). One patient exhibited a hybrid AR indifferent phenotype. While strikingly different from PC morphologically and phenotypically, our data suggest that DSRCT is a second androgen-stimulated malignancy (third if we consider breast cancers that rely on shared nuclear receptor family signaling). Shared dependence upon AR for tumor growth and survival provides an exciting opportunity to prospectively study AR signaling in a different cancer type and younger DSRCT-stricken patient population. Ongoing work will determine if DSRCT undergoes dedifferentiation towards a more stem-like cell as an intermediary step before undergoing neural lineage commitment or transdifferentiation directly from an epithelial cell type towards a neuroendocrine cell fate. We are also exploring if the FP acts as a Pioneer factor to direct AR towards DSRCT-specific androgen response elements that explain this sarcoma subtype’s unique clinical presentation. Citation Format: Danh D. Truong, Salah-Eddine Lamhamedi-Cherradi, Mayinuer Maitituoheti, Hannah C. Beird, Chia-Chin Wu, Sandhya Krishnan, Davis Ingram, P. Andrew Futreal, Mark Titus, Alexander Lazar, Kunal Rai, A. Robert MacLeod, Najat C. Daw, Andrea Hayes, Joseph Ludwig. The epigenetic impact and therapeutic opportunity of AR-directed therapy for desmoplastic small round cell tumor [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr A082.

Deep multi-omic analyses to identify targetable pathways in desmoplastic small round cell tumor (DSRCT) with opportunities for clinical intervention.

e22006 Background: DSRCT is an extremely rare and highly aggressive soft-tissue sarcoma affecting adolescents and young adults with male predominance. The 5-year overall survival is &lt; 25% despite intensive multi-modality treatment including aggressive surgical resection, radiotherapy, chemotherapy, and targeted therapy. Therefore, more effective and innovative therapeutic options are urgently needed. Recent advances in genomic, epigenomic, proteomic, and immune profiling have uncovered a large number of therapeutic targets that are transforming the field of cancer medicine. This study aimed to identify novel targetable pathways in DSRCT using a deep multi-omics-based platform. Methods: Three patients with biopsy proven metastatic DSRCT were enrolled under an IRB-approved observational study within the “Serial Measurements of Molecular and Architectural Responses to Therapy” (SMMART) program at OHSU. Biopsies taken at enrollment were analyzed with targeted DNA sequencing, whole transcriptome sequencing, immunohistochemistry (IHC), NanoString GeoMx digital spatial profiling (DSP) multiplexed proteomics, single cell cyclic immunofluorescence (Cyc-IF), and reverse phase protein array (RPPA). Results: Multiple clinically relevant targets were identified, including HER2, androgen receptor (AR), elevated DNA damage response, and MAPK and mTOR signaling pathways. All three DSRCTs expressed HER2: clinical IHC identified HER2 low (1+) to HER2 equivocal (2+) expression; DSP analysis showed high HER2 and phospho-HER2 expression; and HER2 RNA expression was elevated compared to the TCGA sarcoma cohort. Two of the three patients displayed high AR protein expression, assessed by clinical IHC (90-100% positive cells) and DSP (top quartile compared to a 20 mixed-subtype breast cancer cohort). Strong evidence of DNA damage response was demonstrated at both RNA and protein levels, and RPPA revealed high PARP1, PAR, p-ATM, p-RPA32, and RAD51. Within cell signaling pathways, one DSRCT exhibited high total and phospho-ERK1/2 protein across all clinical and exploratory assays, while another patient displayed evidence of elevated mTOR pathway signaling by RPPA. Conclusions: Overall, this multi-omic analysis provided new insights into possible therapeutic targets for this rare and difficult to treat sarcoma subtype. Results from this study will be further validated in vivo using patient-derived xenograft (PDX) models, providing support for development of multiple early phase trials.

Effectiveness of irinotecan plus trabectedin on a desmoplastic small round cell tumor patient-derived xenograft.

This study exploited a novel patient-derived xenograft (PDX) of desmoplastic small round cell tumor (DSRCT), which reproduces histomorphological and molecular characteristics of the clinical tumor, to assess the activity of cytotoxic and targeted anticancer agents. Antitumor effect was moderate for doxorubicin, pazopanib and larotrectenib [maximum tumor volume inhibition (max TVI), 55-66%], while trabectedin had higher activity (max TVI, 82%). Vinorelbine, irinotecan and eribulin achieved nearly complete tumor growth inhibition (max TVI, 96-98%), although tumors regrew after the end of treatment. The combination of irinotecan with either eribulin or trabectedin resulted in complete responses, which were maintained until the end of the experiment for irinotecan plus trabectedin. Irinotecan-based combinations nearly abrogated the expression of proteins of the G2/M checkpoint, preventing cell entrance in mitosis, and induced apoptotic and necroptotic cell death. Consistently, irinotecan plus trabectedin resulted in reprogramming of DSCRT transcriptome, with downregulation of E2F targets, G2/M checkpoint and mitotic spindle gene sets. This study emphasizes the importance of patient-derived preclinical models to explore new treatments for DSRCT and fosters clinical investigation into the activity of irinotecan plus trabectedin.

A multicenter, phase II trial of maintenance sirolimus in combination with metronomic chemotherapy in children and adolescents with high-risk solid tumors.

TPS10072 Background: Risk of relapse for children with high-risk solid tumors (ST) remains unacceptably high despite aggressive multimodal therapy. Maintenance therapy is an emerging option to improve outcomes. Sirolimus, an inhibitor of mammalian target of rapamycin, is a potent immunosuppressant with antiproliferative and antiangiogenic effects. Low-dose metronomic chemotherapy along with the cyclooxygenase-2 inhibitor celecoxib also decreases neovascularization in in vitro and in vivo systems. The maximum tolerated dose (MTD) of sirolimus in combination with celecoxib and etoposide alternating with cyclophosphamide was determined in a phase I study in pediatric patients with relapsed/refractory ST. The regimen was well-tolerated and showed best response of stable disease in 8/18 subjects and partial response in 1/18. The efficacy of this regimen in relapsed/refractory ST is being tested in a Phase II study (NCT02574728). We hypothesize that patients with high-risk ST administered a 12-month course of this maintenance regimen will have improved 2-year progression-free survival (PFS) when compared to matched historical patients who were observed following completion of upfront therapy. Methods: This is a phase II study of sirolimus in combination with celecoxib and alternating low-dose etoposide and cyclophosphamide delivered as maintenance therapy. Sirolimus will be given at the MTD of 2mg/m2/day with celecoxib 100mg twice daily and oral etoposide 50mg/m2/day (max 100mg) alternating every 21 days with oral cyclophosphamide 2.5mg/kg/day (max 100mg). This study includes: 1) a prospective cohort of patients with high-risk ST in first complete remission (CR), 2) a prospective cohort of patients with recurrent ST in second CR, and 3) a historical cohort matched 2:1 with cohort 1 on diagnosis, age, metastatic sites, and date of diagnosis treated with observation following upfront therapy. The study will enroll up to 38 patients in cohort 1. Eligible subjects are children (1-30 years) with a diagnosis of high-risk extracranial ST (metastatic sarcoma, desmoplastic small round cell tumor, malignant rhabdoid tumor) in first CR or any ST in second CR. Patients enrolled in upfront clinical trials are excluded. Primary endpoint is 2-year PFS of cohort 1 compared to the historical cohort. Secondary endpoints are median PFS of cohort 1, 2-year PFS and overall survival of cohorts 1 and 2, incidence of severe toxicities, and feasibility of completing the 12-month course following standard upfront therapy. Exploratory objectives include evaluation of circulating tumor DNA (ctDNA) in this population of patients in CR or with minimal disease burden and correlation of clinically obtained tumor molecular profiling with outcomes. As of January 2023, 12 subjects are enrolled, 9 in cohort 1 and 3 in cohort 2. Clinical trial information: NCT04469530 .

Efficacy of eribulin administered in combination with an immune checkpoint inhibitor (ICI) and anlotinib as salvage treatment for patients (pts) with advanced adult soft tissue sarcoma (STS).

11572 Background: Eribulin combined with a multi-targeted antiangiogenic tyrosine kinase inhibitor has shown efficacy in STS. ICIs have also exhibited improved survival in some STS subtypes. We investigated the efficacy and safety of triple combination therapy with eribulin, an ICI and anlotinib in the treatment of advanced STS in an adult Chinese population. Methods: This study retrospectively analyzed data from patients diagnosed with advanced STS who received combination therapy with eribulin, an ICI and anlotinib at the Department of Oncology, Zhongshan Hospital affiliated to Fudan University. The primary endpoint was progression-free survival (PFS). Secondary endpoints included objective response rate (ORR) by RECIST v1.1, disease control rate (DCR), and treatment-related adverse events (TRAEs) by CTCAE v5.0. Results: Medical records from 32 pts treated between August 15, 2020 and January 31, 2023 were included; the median age was 56 years, 71.8% (23/32) were female, 75.0% (24/32) had an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1, and 25.0% (8/32) had an ECOG PS of 2. Pts had received a median of 2 (range 0-6) prior regimens and the median follow-up was 4.1 months. Among the patients, 50.0% (16/32) had liposarcomas (including 1 with pleomorphic liposarcoma and 15 with dedifferentiated liposarcoma [DDLPS]), 31.3% (10/32) had leiomyosarcomas (LMS), 3 had undifferentiated pleomorphic sarcoma (UPS), and 1 each had angiosarcoma, rhabdomyosarcoma and desmoplastic small round cell tumor. In a preliminary analysis, 29 pts were evaluable for clinical activity; partial responses (PRs) were achieved in 3 pts (2 DDLPS, 1 UPS), the ORR and DCR were 10.3% (3/29) and 62.1% (18/29) respectively, and the median PFS was 5.7 months (95% CI 2.7-9.8). Of the 15 pts with DDLPS (median 1 prior line of therapy; median follow-up 6.3 months), 13 were evaluable for clinical activity; a PR was achieved by 15.4% (2/13), the DCR was 61.5% (8/13), the median PFS was 9.8 months (95% CI 1.8-28.5) and treatment was ongoing in 46.7% of pts (n = 7). Among the 9 evaluable pts with LMS, 0 achieved a PR, the DCR was 44.4% (4/9), median PFS was 3.9 months and 3 pts were still receiving treatment. In the overall cohort (n = 32), TRAEs of any grade occurred in 56.3% of pts (n = 18), the most common were myelosuppression (28.1%), fatigue (15.6%), fever (12.5%) and rash (12.5%). Grade 3/4 TRAEs occurred in 12.5% of pts, with no grade 5 events. Conclusions: This study demonstrates the potential efficacy of combination therapy with eribulin, an ICI and anlotinib in patients with advanced STS, especially in those with the DDLPS subtype. Our data suggest that this combination has good tolerability and a prospective trial is warranted. Clinical trial information: ChiCTR2100053594.

First person – Valentina Zuco

ABSTRACT First Person is a series of interviews with the first authors of a selection of papers published in Disease Models &amp; Mechanisms, helping researchers promote themselves alongside their papers. Valentina Zuco is first author on ‘ Effects of irinotecan plus trabectedin on a desmoplastic small round cell tumor patient-derived xenograft’, published in DMM. Valentina is a scientist in the lab of Nadia Zaffaroni at Fondazione IRCCS Istituto Tumori, Milan, Italy, investigating patient-derived tumor models to identify new therapeutic strategies for patients with rare cancers to be translated into clinical trials.

A phase II study of fruquintinib in the first- (1L) or second-line (2L) treatment of unresectable metastatic soft tissue sarcoma.

e23547 Background: Standard treatment for patients with unresectable metastatic soft-tissue sarcoma is chemotherapy based on anthracyclines, while the tolerance of chemotherapy is limited. We assessed if fruquintinib, a highly selective tyrosine kinase inhibitor of VEGFR-1, -2, and -3 is effective and safe in the 1L or 2L treatment for these patients. Methods: This is a single-arm, prospective, single-center clinical study. The inclusion criteria were patients with pathologically confirmed unresectable metastatic STS (including desmoplastic small round cell tumors, epithelioid hemangioendothelioma, hemangiopericytoma/malignant solitary fibroma, and chemotherapy-failed hemangiosarcoma), at least one measurable lesion (according to RECIST 1.1), with the normal function of main organs. Other inclusion criteria included ECOG PS 0-2 and anti-angiogenesis treatment naïve. Patients were administrated 5mg fruquintinib once daily for 3 weeks every 4 weeks until disease progression or unacceptable toxicity. The primary study endpoint was Progression free survival (PFS). Objective response rate (ORR), disease control rate (DCR), duration of response (DoR) and adverse event was also calculated. Results: Data cutoff date was January 31 2023. 14 patients (9 males and 5 females) were enrolled. The median age is 50.1 (range 21-69). Pathological types included: Hemangiopericytoma/malignant solitary fibroma (n=6); Epithelioid Hemangioendothelioma (n=6) and Hemangiosarcoma (n=2). 2 patients were died, the median PFS was 8.1 m. 14 patients were eligible for the evaluation of tumor response. 3 patients (2 cases of Hemangiosarcoma and 1 case of Epithelioid Hemangioendothelioma) achieved partial response (PR) and the ORR was 21.4 %(3/14). 10 patients had stable disease (SD) and the DCR was 92.9% (13/14). Most adverse events were hypertension, fatigue, and hemorrhage. The most Grade 3/4 adverse effect is hypertension and abnormal liver function. Conclusions: The fruquintinib showed a promising efficacy and favorable tolerance in the 1L or 2L treatment of unresectable metastatic soft-tissue sarcoma. Clinical trial information: NCT05142631 .

Dissociation protocols used for sarcoma tissues bias the transcriptome observed in single-cell and single-nucleus RNA sequencing

BackgroundSingle-cell RNA-seq has emerged as an innovative technology used to study complex tissues and characterize cell types, states, and lineages at a single-cell level. Classification of bulk tumors by their individual cellular constituents has also created new opportunities to generate single-cell atlases for many organs, cancers, and developmental models. Despite the tremendous promise of this technology, recent evidence studying epithelial tissues and diverse carcinomas suggests the methods used for tissue processing, cell disaggregation, and preservation can significantly bias gene expression and alter the observed cell types. To determine whether sarcomas – tumors of mesenchymal origin – are subject to the same technical artifacts, we profiled patient-derived tumor explants (PDXs) propagated from three aggressive subtypes: osteosarcoma (OS), Ewing sarcoma (ES), desmoplastic small round cell tumor (DSRCT). Given the rarity of these sarcoma subtypes, we explored whether single-nuclei RNA-seq from more widely available archival frozen specimens could accurately be identified by gene expression signatures linked to tissue phenotype or pathognomonic fusion proteins.ResultsWe systematically assessed dissociation methods across different sarcoma subtypes. We compared gene expression from single-cell and single-nucleus RNA-sequencing of 125,831 whole-cells and nuclei from ES, DSRCT, and OS PDXs. We detected warm dissociation artifacts in single-cell samples and gene length bias in single-nucleus samples. Classic sarcoma gene signatures were observed regardless of the dissociation method. In addition, we showed that dissociation method biases could be computationally corrected.ConclusionsWe highlighted transcriptional biases, including warm dissociation and gene-length biases, introduced by the dissociation method for various sarcoma subtypes. This work is the first to characterize how the dissociation methods used for sc/snRNA-seq may affect the interpretation of the molecular features in sarcoma PDXs.

Intra-abdominal desmoplastic small round cell tumor: The European pediatric Soft tissue sarcoma Study Group (EpSSG) experience.

This study describes the clinical findings of a consecutive series of pediatric and adolescent patients with a diagnosis of intra-abdominal desmoplastic small round cell tumor (DSRCT) prospectively enrolled in European pediatric Soft tissue sarcoma Study Group (EpSSG) protocols: the BERNIE study, the EpSSG MTS 2008 study, and the EpSSG NRSTS 2005 study. Patients aged less than 21years with a diagnosis of DSRCT arising in the abdomen were included. All trials recommended a multimodal approach including intensive multidrug chemotherapy and loco-regional treatment with surgery and/or radiotherapy whenever possible. The analysis included 32 cases (median age 13.7years, male:female ratio 1.5:1). Three patients had localized tumors, seven had regionally disseminated disease, and 22 extraperitoneal metastases. All but one patient received multidrug chemotherapy and 11 had maintenance chemotherapy. Loco-regional treatment consisted of surgery only in seven cases, surgery plus adjuvant radiotherapy in 10, and radiotherapy only in six. Among the 17 cases who had radiotherapy, six had irradiation of the primary site, 10 had whole abdominopelvic radiotherapy plus boost to macroscopic residual disease, and one had irradiation to lung metastases only. With a median follow-up of 76months (range: 18-124months), 5-year event-free and overall survivals were 19.7% and 21.0%, respectively. Event-free survival was significantly worse for patients who did not receive loco-regional treatment (p-value .007). The study confirmed that the outcome of patients with DSRCT remains dismal and did not improve over recent years despite an intensive multimodal treatment approach.