A Systemic Review of Primary Malignant Long Bone Tumors in Children and Adolescents.

PURPOSE OF THE STUDY: Managing bone tumours is complex, relying on limited evidence, expert opinions, and retrospective reviews. Multidisciplinary approaches and early diagnosis are crucial for better outcomes, especially in young patients with growing skeletons. The aim of this systemic review and meta-analysis is to give a comprehensive review of common malignant tumors affecting long bones in children and adolescents. MATERIAL AND METHODS: A PubMed/Medline search for "primary malignant long bone tumours in children" initially retrieved 1120 papers, which were subsequently narrowed down to 110 articles based on inclusion and exclusion criteria. These articles were reviewed, focusing on clinical presentation, diagnostic workup, treatment options, surgical planning, and variations in presentation, including rare tumours. The two most commonly reported tumours were osteosarcoma and Ewing sarcoma, leading to the division of studies into five groups. The inclusion criteria encompassed malignancies in patients aged 2-25 years, work-up, imaging, surgical treatment, rare tumour case reports, and surgical management principles, resulting in a heterogeneous group of articles. To enhance categorisation, it was clarified that studies with 10 or more cases were considered retrospective reviews. RESULTS: Reviewing of results thus demonstrate that the two likely tumours in children under consideration were osteosarcoma and Ewing sarcoma. Their presentation findings and clinical features were discussed in detail in the review. It is worth noting here that in case of differential diagnosis this should be the first on the list. DISCUSSION AND CONCLUSIONS: Although focus of literature is more on the two most common tumours. However, rare tumours should be considered as they can mimic these common tumors. KEY WORDS: primary, malignant, bone tumors, children, adolescent.

Emerging therapies in Ewing sarcoma.

PURPOSE OF REVIEW: There is an unmet need to improve outcomes for patients for Ewing sarcoma, a rare, aggressive sarcoma with a peak incidence in adolescents and young adults (AYA). Current therapy at diagnosis involves multiagent chemotherapy and local therapy, but despite intensification of treatment, those with metastases at diagnosis and recurrent disease have poor outcomes. RECENT FINDINGS: Improved understanding of Ewing sarcoma biology has identified novel targets with promising activity in Ewing sarcoma patients, including tyrosine kinase inhibitors that are now undergoing evaluation as combination and maintenance therapy. Other emerging therapies include those that target the EWSR1::FLI1 fusion oncoprotein, and act on DNA damage, cell cycle and apoptotic pathways. Immunotherapeutic approaches, particularly CAR-T-cell therapy directed at GD2, also hold promise. Recent collaborative clinical trials that have defined an international standard of care for patients with newly diagnosed Ewing sarcoma and novel platform studies with adaptive designs offer unique opportunities to investigate these therapies inclusive of all ages. SUMMARY: Close international collaboration between clinicians and biologists will allow us to prioritize promising emerging therapies and develop biomarkers to facilitate their incorporation into standard of care and more rapidly translate into benefit for Ewing sarcoma patients.

[Analysis of 41 cases of non-metastatic Ewing's sarcoma in children]. / 儿童非转移性尤文肉瘤41例分析.

OBJECTIVES: To summarize the clinical characteristics, treatment outcomes, and prognostic factors of children with non-metastatic Ewing's sarcoma (ES). METHODS: A retrospective analysis was conducted on the clinical data of 41 children with non-metastatic ES diagnosed and treated at the Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine from January 2010 to December 2018. All patients underwent chemotherapy based on the RMS-2009 protocol of the center, and local treatment such as surgery and/or radiotherapy was performed according to risk grouping. The Kaplan-Meier method was used to calculate the overall survival (OS) and event-free survival (EFS) rates. Univariate prognostic analysis was performed using the log-rank test, and multivariate analysis was conducted with Cox regression. RESULTS: Of the 41 children, 21 were male and 20 were female. The median age at diagnosis was 7.7 years (range: 1.2-14.6 years). The median follow-up time for patients with event-free survival was 68.1 months (range: 8.1-151.7 months). As of the last follow-up, 33 patients were in complete remission, and the overall 5-year EFS and OS rates were (78±6)% and (82±6)%, respectively. Univariate analysis by the log-rank test showed that a tumor diameter ≥8 cm, time from diagnosis to start of local treatment ≥16 weeks, and incomplete surgical resection were associated with poor prognosis (P<0.05). Multivariate Cox regression analysis indicated that incomplete surgical resection (HR=8.381, 95%CI: 1.681-41.801, P=0.010) was an independent risk factor for poor prognosis in children with ES. Secondary tumors occurred in 2 cases. CONCLUSIONS: A comprehensive treatment strategy incorporating chemotherapy, surgery, and radiotherapy can improve the prognosis of children with ES. Poor prognosis is associated with an initial tumor diameter ≥8 cm, while complete surgical resection and early initiation of local treatment can improve outcomes.

Extraskeletal Ewing's sarcoma of supraglottis: A rare case report.

Ewing's Sarcoma family of tumors is a group of small round tumor cells. Ewing's sarcoma majority occurs in bone, accounts about 10 % of primary bone tumors. Extraskeletal Ewing's sarcoma (ESS) is unusual and commonly seen in trunk, paravertebral, and chest wall region. It is rarely seen in head and neck region, accounting to 2-3 %. In head and neck region, ESS is seen in nasal or oral cavities, sinuses. EES originating in the larynx is very rare. Here, we report a 22 years old female having the complaints of change in voice and noisy breathing who was diagnosed as a case of EES of supraglottis. As the disease progressed during the time of diagnosis, she had to undergo emergency tracheostomy. The disease was inoperable so she received neoadjuvant chemotherapy followed by radiation followed by adjuvant chemotherapy. At present she is symptomatically better. The aim of this report is to put forward the rare site of Ewing's Sarcoma and highlighting the early diagnosis in suspected case with IHC, providing effective multimodality treatment.

Survival outcomes in pediatric patients with metastatic Ewing sarcoma who achieve a rapid complete response of pulmonary metastases.

PURPOSE: Our objectives were to compare overall survival (OS) and pulmonary relapse between patients with metastatic Ewing sarcoma (EWS) at diagnosis who achieve rapid complete response (RCR) and those with residual pulmonary nodules after induction chemotherapy (non-RCR). PATIENTS AND METHODS: This retrospective cohort study included children under 20 years with metastatic EWS treated from 2007 to 2020 at 19 institutions in the Pediatric Surgical Oncology Research Collaborative. Chi-square tests were conducted for differences among groups. Kaplan-Meier curves were generated for OS and pulmonary relapse. RESULTS: Among 148 patients with metastatic EWS at diagnosis, 61 (41.2%) achieved RCR. Five-year OS was 71.2% for patients who achieved RCR, and 50.2% for those without RCR (p = .04), and in multivariable regression among patients with isolated pulmonary metastases, RCR (hazards ratio [HR] 0.42; 95% confidence interval [CI]: 0.17-0.99) and whole lung irradiation (WLI) (HR 0.35; 95% CI: 0.16-0.77) were associated with improved survival. Pulmonary relapse occurred in 57 (37%) patients, including 18 (29%) in the RCR and 36 (41%) in the non-RCR groups (p = .14). Five-year pulmonary relapse rates did not significantly differ based on RCR (33.0%) versus non-RCR (47.0%, p = .13), or WLI (38.8%) versus no WLI (46.0%, p = .32). DISCUSSION: Patients with EWS who had isolated pulmonary metastases at diagnosis had improved OS if they achieved RCR and received WLI, despite having no significant differences in rates of pulmonary relapse.

Malignant tumour in pregnancy: Ewing-like sarcoma of the gluteal region.

We report a case of an Ewing-like sarcoma of the gluteal region with ongoing growth during the second trimester of pregnancy and noted during the third trimester. This lesion was consequently studied to infer its malignant potential. Several examinations were conducted to characterise this lesion, such as ultrasound and MR, which showed signs of tumourous invasion of the deep tissues of the gluteal region.Given that the pregnancy was at the end of the third trimester, the decision was made to schedule the delivery at 37 weeks of gestation and treat the tumour afterwards to balance maternal and fetal health.This case illustrates the need for a detailed investigation and guidance by a multidisciplinary team to provide prenatal counselling regarding a malignant tumour during pregnancy.

Clinical outcomes of patients with CIC-rearranged sarcoma: a single institution retrospective analysis.

PURPOSE: CIC-rearranged sarcomas represent a type of undifferentiated small round cell sarcoma (USRCS) characterized by poor survival, rapid development of chemotherapy resistance, and high rates of metastasis. We aim to contribute to the growing body of knowledge regarding diagnosis, treatment, clinical course, and outcomes for these patients. METHODS: This case series investigates the clinical courses of ten patients with CIC-rearranged sarcoma treated at the Johns Hopkins Hospital from July 2014 through January 2024. Clinical data were retrospectively extracted from electronic medical records. RESULTS: Patients ranged from 10 to 67 years of age at diagnosis, with seven patients presenting with localized disease and three with metastatic disease. Tumors originated from soft tissues of various anatomic locations. Mean overall survival (OS) was 22.1 months (10.6-52.2), and mean progression-free survival (PFS) was 16.7 months (5.3-52.2). Seven patients received intensive systemic therapy with an Ewing sarcoma-directed regimen or a soft tissue sarcoma-directed regimen. Three patients experienced prolonged disease-free survival without systemic treatment. CONCLUSION: Most patients in this case series demonstrated aggressive clinical courses consistent with those previously described in the literature, although we note a spectrum of clinical outcomes not previously reported. The diversity of clinical courses underscores the need for an improved understanding of individual tumor biology to enhance clinical decision-making and patient prognosis. Despite its limitations, this article broadens the spectrum of reported clinical outcomes, providing a valuable addition to the published literature on this rare cancer.

Ewing's sarcoma in adolescents and adults - 10-year experience from a tertiary cancer center in India.

BACKGROUND: Ewing's sarcoma (EWS) is an aggressive small round cell tumor, affecting bone and soft tissues and is mostly seen in childhood and second decade of life. EWS accounts for 10-12% of bone tumors in more than 15 years age group and is even rarer after 40 years of age. MATERIALS AND METHODS: This retrospective analysis was conducted among patients aged more than 15 years with histologically proven EWS. RESULTS: Among 240 cases of EWS treated at our center during 2001-2010, 130 (54%) were more than 15 years of age. The median age was 20 years with a male: female ratio of 2.4:1. Ninety percent had skeletal EWS, 10% had extra skeletal EWS, and 37% patients were metastatic at presentation. Eighty-two received curative treatment with chemotherapy (vincristine, doxorubicin, cyclophosphamide, ifosfamide, etoposide (VAC/IE)) along with local treatment, radiotherapy (RT) in 61, surgery alone in seven, and RT plus surgery in 14. Two- and 5-year overall survival (OS) was 43.3% and 25.5%, respectively, for the entire series. The OS for the non-metastatic group was 63.2% at 2 years and 36.5% at 5 years, and the progression free survival was 53.7% at 2 years and 37.8% at 5 years. High lactate dehydrogenase was found to be a significant poor prognostic factor (P = 0.001). Median OS for localized central EWS was 49.2 months and that for peripheral EWS was 24 months. Patients more than 20 years of age with non-metastatic disease had better OS compared to those with 15-20 years of age. CONCLUSION: Treatment of EWS requires a multidisciplinary approach with radical surgery and/or radiation to control local disease and multiagent chemotherapy to control systemic disease. Long-term follow-up is essential because of disease relapse and treatment-related complications.

Primary extraskeletal intradural Ewing sarcoma with acute hemorrhage: a case report and review of the literature.

BACKGROUND: Spinal cord tumors present a challenge in diagnosis and treatment due to their varied histopathological characteristics. While Ewing sarcoma is a rare malignant tumor typically originating from skeletal bone, cases of primary intradural extraskeletal Ewing sarcoma are exceptionally rare. The similarity of its presentation to other spinal tumors further complicates its identification and management. CASE PRESENTATION: We report a case of a 58-year-old Palestinian male with intradural extraskeletal lumbar Ewing sarcoma. The patient initially presented with lower back pain and bilateral S1 radiculopathy, with more severe symptoms on the left side. Magnetic resonance imaging revealed a 7 cm oval-shaped mass with homogeneous contrast enhancement, obstructing the spinal canal from L3/L4 to L5/S1 levels. Initially, a myxopapillary ependymoma was suspected, but the patient's sensory and motor functions suddenly deteriorated during hospitalization. Repeat magnetic resonance imaging indicated heterogeneous contrast enhancement, indicating acute intratumoral hemorrhage. Consequently, the patient underwent emergent L3-L5 laminotomy, with successful gross total resection of the tumor. Histopathological and immunohistochemical analyses confirmed the diagnosis of intradural extraskeletal Ewing sarcoma. Adjuvant therapy was administered to minimize the risk of local recurrence or distant metastasis. A systematic review of relevant literature, along with retrospective analysis of medical records, operative reports, radiological studies, and histopathological findings of similar cases, was also conducted. CONCLUSIONS: Intradural extraskeletal Ewing sarcoma is an infrequently encountered condition in adult patients, emphasizing the importance of considering it in the differential diagnosis of spinal tumors. Surgeons must possess a comprehensive understanding of this rare entity to ensure accurate staging and optimal management, particularly in the early stages when prompt intervention may improve prognosis.

Ewing sarcoma of the cervix: an unusual site of presentation.

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

Engineering small-molecule and protein drugs for targeting bone tumors.

Bone cancer is common and severe. Both primary (e.g., osteosarcoma, Ewing sarcoma) and secondary (e.g., metastatic) bone cancers lead to significant health problems and death. Currently, treatments such as chemotherapy, hormone therapy, and radiation therapy are used to treat bone cancer, but they often only shrink or slow tumor growth and do not eliminate cancer completely. The bone microenvironment contributes unique signals that influence cancer growth, immunogenicity, and metastasis. Traditional cancer therapies have limited effectiveness due to off-target effects and poor distribution on bones. As a result, therapies with improved specificity and efficacy for treating bone tumors are highly needed. One of the most promising strategies involves the targeted delivery of pharmaceutical agents to the site of bone cancer by introduction of bone-targeting moieties, such as bisphosphonates or oligopeptides. These moieties have high affinities to the bone hydroxyapatite matrix, a structure found exclusively in skeletal tissue, and can enhance the targeting ability and efficacy of anticancer drugs when combating bone tumors. This review focuses on the engineering of small molecules and proteins with bone-targeting moieties for the treatment of bone tumors.

Incidence of skeletal-related events in patients with Ewing sarcoma: An observational retrospective study in Japan.

BACKGROUND: Skeletal-related events (SREs), including the pathological fracture, surgical treatment or radiation of bone lesions, malignant spinal cord compression, hypercalcemia, are important considerations when managing metastatic bone tumors; however, owing to their rarity, the incidence of SREs in patients with Ewing sarcoma remains unknown. METHODS: We retrospectively reviewed the clinical data from 146 patients with Ewing sarcoma treated at a single institution from 2005 to 2019. The median age at diagnosis was 22.7 years. Fifty patients (34.2%) had metastatic disease at diagnosis. The primary outcome was the SRE-free rate among patients with Ewing sarcoma. Moreover, we identified the risk factors for SREs using univariate or multivariate analyses. RESULTS: During the observational period (median, 2.6 years), SREs occurred in 23 patients. Radiation to the bone, malignant spinal cord compression, and hypercalcemia were documented as the initial SREs in 12 patients (52.2%), 10 patients (43.5%), and one patient (4.3%), respectively. The SRE-free rate was 94.2 ± 2.0, 87.3 ± 3.0, and 79.6 ± 3.8% at 1, 2, and 3 years after the initial visit, respectively. Multivariate analysis revealed bone metastasis at diagnosis (hazard ratio [HR] = 4.41, p = 0.007), bone marrow invasion (HR = 34.08, p < 0.001), and local progression or recurrence after definitive treatment (HR = 3.98, p = 0.012) as independent risk factors for SREs. CONCLUSIONS: SREs are non-rare events that can occur during the treatment course for Ewing sarcoma, with an especially high incidence of malignant spinal cord compression. Patients with metastatic disease at diagnosis, especially in the bone or bone marrow, or with local progression or recurrence after definitive treatment, should be carefully monitored for the occurrence of SREs. The most effective methods to monitor the occurrence of SREs and new preventative therapies for SREs should be investigated in the future.

The significance of surveillance imaging in children with Ewing sarcoma and osteosarcoma.

Primary bone tumors in children and adolescents, while rare, pose significant challenges in diagnosis and management. Children treated for Ewing sarcoma and osteosarcoma are offered a 5-year follow-up program after end of treatment, including radiological surveillance of primary location of tumor and the lungs. There is no consensus regarding how often and how the children should be followed with radiological imaging. This retrospective descriptive study of 69 patients (34 with Ewing sarcoma and 35 with osteosarcoma) investigated the consequences of abnormal findings in 1279 follow-up images. Nine relapses were detected, 4 in the Ewing group (3 local and 1 pulmonary) and 5 in the osteosarcoma group (1 local and 4 pulmonary). Of these, only two patients exhibited symptomatic relapses, with the remainder identified through imaging. The positive predictive value for relapse detection was 0.44 in the Ewing group, and 0.5 in the osteosarcoma group. In the Ewing sarcoma patient image follow-up program, the probability of anomaly detection was 12% (95% CI, 10-15). For osteosarcoma patients, the likelihood was 6% (95% CI, 4-8). Our data indicates that abnormal findings on follow-up images rarely represents relapse of tumor. As the surveillance protocol differs between the patient groups, wherein Ewing sarcoma patients primarily are monitored through MRI while osteosarcoma patients are predominantly tracked via X-rays, there is an increased occurrence of incidental findings in the first group. However, it is imperative to interpret imaging data in conjunction with clinical information, avoiding isolated reliance on imaging results when making treatment decisions.

Survival and treatment in older patients with ewing sarcoma: an analysis of the national cancer database.

BACKGROUND: Ewing sarcoma (EWS) is a malignancy which primarily arises in adolescence and has been studied extensively in this population. Much less is known about the rare patient cohort over the age of 40 at diagnosis. In this study, we describe the survival outcomes and clinical characteristics of this population. METHODS: This retrospective cohort study utilized the National Cancer Database (NCDB) to identify 4600 patients diagnosed between 2004 through 2019. Of these patients, 4058 were under the age of 40 and 542 were over 40. Propensity score 1:1 matching was performed according to sex and race. Univariate and multivariate logistic regression was performed to generate odds ratios (OR) and a Multivariate Cox regression model was used to generate a hazard ratio (HR) for patients over 40. Kaplan-Meier curves were used to estimate survival from diagnosis to death between age groups. Chi-square tests were used to compare demographic and socioeconomic patient characteristics. IBM statistics version 27.0 was used. p < 0.05 was used to indicate statistical significance. RESULTS: EWS patients older than 40 experienced worse survival outcomes compared to patients under the age of 40. 5-year survival was 44.6% for older patients vs. 61.8% for younger patients (p < 0.05). A multivariate Cox proportional hazards model showed that age was independently associated with inferior survival. (HR 1.96; p < 0.05). EWS patients over the age of 40 were more likely to have tumors originating from the vertebral column (16.1% vs 8.9%; p < 0.05) and cranium (5.3% vs. 2.9%; p < 0.05) and had a higher rate of axial tumors (31.6% vs. 18.5%; p < 0.05) compared to patients under 40. Additionally, patients older than 40 experienced a significantly longer delay between the date of diagnosis and initiation of systemic treatment (36.7 days vs. 24.8 days; p < 0.05) and were less likely to receive adjuvant chemotherapy (93.4% vs. 97.9%; p < 0.05). CONCLUSION: An age over 40 is associated with decreased survival for patients with EWS. Due to the rarity of EWS in this cohort, the optimal role of systemic treatment remains unknown and has yet to be clearly elucidated. Consequently, our findings suggest that older patients receive disparities in treatment which may be contributing to decreased survival rates.

Gastrointestinal Ewing Sarcoma: A Clinicopathological and Molecular Genetic Analysis of 25 Cases.

Occurrence of extraskeletal Ewing sarcoma (ES) in the gastrointestinal (GI) tract is extremely rare. Here, we report 25 cases of ES arising primarily in the GI tract with a focus on the clinicopathological and molecular features, differential diagnosis, and biological behavior. Thirteen patients (52%) were male, and 12 (48%) were female with age ranging from 9 to 59 years (mean: 36.2 years; median: 38 years). Twenty-one tumors (84%) occurred in the small intestine, 3 (12%) in the stomach, and 1 (4%) in the anal canal. At operation, 8/18 (44.4%) patients presented with abdominopelvic disseminated disease. Tumor size measured from 2 to 25 cm (mean: 8.2 cm; median: 6 cm) in maximum size. Microscopically, the tumors were composed of infiltrative small round, ovoid, or short spindle cells arranged mostly in lobular and solid sheet-like patterns with a rich capillary vasculature. Focal formation of Homer Wright-type rosettes and pseudoalveolar architecture was noted each in 2 (8%) cases and 3 (12%) cases. Besides CD99 (25/25; 100%), Fli-1 (15/15, 100%), and NKX2.2 (14/16; 87.5%), the tumor cells also showed variable staining of CD117 (14/17; 82.4%). Of 25 cases, 23 (92%) demonstrated EWSR1 rearrangement by fluorescence in situ hybridization analysis. The 2 cases with negative fluorescence in situ hybridization results were found to harbor EWSR1::ERG and EWSR1::FLI1 fusion by further RNA sequencing, respectively, with a median follow-up of 12 months (range: 1 to 42 months), 5/19 (26.3%) patients developed visceral metastasis and 12/19 (63.2%) patients died of the disease (range:1 to 33 months; median: 9 months). This study showed that GI ES had a predilection for the small intestine, although other sites of the GI tract could also be involved. GI ES had a poor prognosis with a high rate of mortality, particularly in patients with abdominopelvic disseminated disease. In light of appropriate therapeutic strategies and prognostic considerations, it is essential not to misdiagnose GI ES as gastrointestinal stromal tumor owing to the expression of aberrant CD117.

Ewing's sarcoma in a young man mimicking lateral elbow pain: A case report with 2 years follow-up.

BACKGROUND AND PURPOSE: Lateral elbow pain represents a common musculoskeletal disorder, mostly non-specific and benign. In rare cases, it can be the first symptom of a severe disease such as Ewing's sarcoma (ES). ES is the second most common primary malignant bone tumor in the young population, with a high probability of an unfavourable prognosis. CASE PRESENTATION: This case report presents the history of a young man presenting to the physical therapist with a diagnosis of "epicondylitis" in the right elbow, which was later revealed to be an aggressive ES of the ulna. Findings raising clinical doubts were (a) constant pain even at night and not dependent on load, (b) significant loss of function, (c) patient's young age, and (d) a palpable mass in the elbow. RESULTS: After diagnosis, the patient received medical (chemotherapy, radiotherapy and surgery) and a rehabilitation program. After treatment, the patient improved elbow function, decreased disability and returned to social participation, maintaining positive outcomes at the 2-year follow-up. DISCUSSION: In summary, this case report emphasizes the importance of differential diagnosis and screening for referral of red flags in physical therapy. Moreover, it describes the rehabilitation of a patient with ES, enriching the scientific literature in the field.

Surface and Global Proteome Analyses Identify ENPP1 and Other Surface Proteins as Actionable Immunotherapeutic Targets in Ewing Sarcoma.

PURPOSE: Ewing sarcoma is the second most common bone sarcoma in children, with 1 case per 1.5 million in the United States. Although the survival rate of patients diagnosed with localized disease is approximately 70%, this decreases to approximately 30% for patients with metastatic disease and only approximately 10% for treatment-refractory disease, which have not changed for decades. Therefore, new therapeutic strategies are urgently needed for metastatic and refractory Ewing sarcoma. EXPERIMENTAL DESIGN: This study analyzed 19 unique Ewing sarcoma patient- or cell line-derived xenografts (from 14 primary and 5 metastatic specimens) using proteomics to identify surface proteins for potential immunotherapeutic targeting. Plasma membranes were enriched using density gradient ultracentrifugation and compared with a reference standard of 12 immortalized non-Ewing sarcoma cell lines prepared in a similar manner. In parallel, global proteome analysis was carried out on each model to complement the surfaceome data. All models were analyzed by Tandem Mass Tags-based mass spectrometry to quantify identified proteins. RESULTS: The surfaceome and global proteome analyses identified 1,131 and 1,030 annotated surface proteins, respectively. Among surface proteins identified, both approaches identified known Ewing sarcoma-associated proteins, including IL1RAP, CD99, STEAP1, and ADGRG2, and many new cell surface targets, including ENPP1 and CDH11. Robust staining of ENPP1 was demonstrated in Ewing sarcoma tumors compared with other childhood sarcomas and normal tissues. CONCLUSIONS: Our comprehensive proteomic characterization of the Ewing sarcoma surfaceome provides a rich resource of surface-expressed proteins in Ewing sarcoma. This dataset provides the preclinical justification for exploration of targets such as ENPP1 for potential immunotherapeutic application in Ewing sarcoma. See related commentary by Bailey, p. 934.

Therapeutic Hope on the Surface of Ewing Sarcoma.

A detailed analysis of the Ewing sarcoma surfacesome has arrived. Robust expression of surface CDH11 and ENPP1 was identified. This "comprehensive catalog" of the Ewing surfacesome serves as a fresh roadmap to development of new therapeutic approaches, including immunotherapies and multi-modality therapeutic combinations, to target aggressive Ewing tumor subpopulations. See related article by Mooney et al., p. 1022.