Search

Background: Osteosarcoma stratification relies on clinical parameters and histological response. We developed a new personalized stratification using less invasive circulating tumor DNA (ctDNA) quantification., Patients and Methods: Plasma from patients homogeneously treated in the prospective protocol OS2006, at diagnosis, before surgery and end of treatment, were sequenced using low-passage whole-genome sequencing (lpWGS) for copy number alteration detection. We developed a prediction tool including ctDNA quantification and known clinical parameters to estimate patients' individual risk of event., Results: ctDNA quantification at diagnosis (diagCPA) was evaluated for 183 patients of the protocol OS2006. diagCPA as a continuous variable was a major prognostic factor, independent of other clinical parameters, including metastatic status [diagCPA hazard ratio (HR) = 3.5, P = 0.002 and 3.51, P = 0.012, for progression-free survival (PFS) and overall survival (OS)]. At the time of surgery and until the end of treatment, diagCPA was also a major prognostic factor independent of histological response (diagCPA HR = 9.2, P < 0.001 and 11.6, P < 0.001, for PFS and OS). Therefore, the addition of diagCPA to metastatic status at diagnosis or poor histological response after surgery improved the prognostic stratification of patients with osteosarcoma. We developed the prediction tool PRONOS to generate individual risk estimations, showing great performance ctDNA quantification at the time of surgery and the end of treatment still required improvement to overcome the low sensitivity of lpWGS and to enable the follow-up of disease progression., Conclusions: The addition of ctDNA quantification to known risk factors improves the estimation of prognosis calculated by our prediction tool PRONOS. To confirm its value, an external validation in the Sarcoma 13 trial is underway., (Copyright © 2023 European Society for Medical Oncology. Published by Elsevier Ltd. All rights reserved.)

Abstract: Small molecules that target the menin-KMT2A protein-protein interaction (menin inhibitors) have recently entered clinical trials in lysine methyltransferase 2A (KMT2A or MLL1)-rearranged (KMT2A-r) and nucleophosmin-mutant (NPM1c) acute myeloid leukemia (AML) and are demonstrating encouraging results. However, rationally chosen combination therapy is needed to improve responses and prevent resistance. We have previously identified IKZF1/IKAROS as a target in KMT2A-r AML and shown in preclinical models that IKAROS protein degradation with lenalidomide or iberdomide has modest single-agent activity yet can synergize with menin inhibitors. Recently, the novel IKAROS degrader mezigdomide was developed with greatly enhanced IKAROS protein degradation. In this study, we show that mezigdomide has increased preclinical activity in vitro as a single-agent in KMT2A-r and NPM1c AML cell lines, including sensitivity in cell lines resistant to lenalidomide and iberdomide. Further, we demonstrate that mezigdomide has the greatest capacity to synergize with and induce apoptosis in combination with menin inhibitors, including in MEN1 mutant models. We show that the superior activity of mezigdomide compared with lenalidomide or iberdomide is due to its increased depth, rate, and duration of IKAROS protein degradation. Single-agent mezigdomide was efficacious in 5 patient-derived xenograft models of KMT2A-r and 1 NPM1c AML. The combination of mezigdomide with the menin inhibitor VTP-50469 increased survival and prevented and overcame MEN1 mutations that mediate resistance in patients receiving menin inhibitor monotherapy. These results support prioritization of mezigdomide for early phase clinical trials in KMT2A-r and NPM1c AML, either as a single agent or in combination with menin inhibitors., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Wilms tumor (WT) is the most common renal malignancy of childhood. Despite improvements in the overall survival, relapse occurs in ~15% of patients with favorable histology WT (FHWT). Half of these patients will succumb to their disease. Identifying novel targeted therapies remains challenging in part due to the lack of faithful preclinical in vitro models. Here we establish twelve patient-derived WT cell lines and demonstrate that these models faithfully recapitulate WT biology using genomic and transcriptomic techniques. We then perform loss-of-function screens to identify the nuclear export gene, XPO1, as a vulnerability. We find that the FDA approved XPO1 inhibitor, KPT-330, suppresses TRIP13 expression, which is required for survival. We further identify synergy between KPT-330 and doxorubicin, a chemotherapy used in high-risk FHWT. Taken together, we identify XPO1 inhibition with KPT-330 as a potential therapeutic option to treat FHWTs and in combination with doxorubicin, leads to durable remissions in vivo., (© 2024. The Author(s).)

Importance: Determining the impact of germline cancer-predisposition variants (CPVs) on outcomes could inform novel approaches to testing and treating children with rhabdomyosarcoma., Objective: To assess whether CPVs are associated with outcome among children with rhabdomyosarcoma., Design, Setting, and Participants: In this cohort study, data were obtained for individuals, aged 0.01-23.23 years, newly diagnosed with rhabdomyosarcoma who were treated across 171 Children's Oncology Group sites from March 15, 1999, to December 8, 2017. Data analysis was performed from June 16, 2021, to May 15, 2023., Exposure: The presence of a CPV in 24 rhabdomyosarcoma-associated cancer-predisposition genes (CPGs) or an expanded set of 63 autosomal-dominant CPGs., Main Outcomes and Measures: Overall survival (OS) and event-free survival (EFS) were the main outcomes, using the Kaplan-Meier estimator to assess survival probabilities and the Cox proportional hazards regression model to adjust for clinical covariates. Analyses were stratified by tumor histology and the fusion status of PAX3 or PAX7 to the FOXO1 gene., Results: In this study of 580 individuals with rhabdomyosarcoma, the median patient age was 5.9 years (range, 0.01-23.23 years), and the male-to-female ratio was 1.5 to 1 (351 [60.5%] male). For patients with CPVs in rhabdomyosarcoma-associated CPGs, EFS was 48.4% compared with 57.8% for patients without a CPV (P = .10), and OS was 53.7% compared with 65.3% for patients without a CPV (P = .06). After adjustment, patients with CPVs had significantly worse OS (adjusted hazard ratio [AHR], 2.49 [95% CI, 1.39-4.45]; P = .002), and the outcomes were not better among patients with embryonal histology (EFS: AHR, 2.25 [95% CI, 1.25-4.06]; P = .007]; OS: AHR, 2.83 [95% CI, 1.47-5.43]; P = .002]). These associations were not due to the development of a second malignant neoplasm, and importantly, patients with fusion-negative rhabdomyosarcoma who harbored a CPV had similarly inferior outcomes as patients with fusion-positive rhabdomyosarcoma without CPVs (EFS: AHR, 1.35 [95% CI, 0.71-2.59]; P = .37; OS: AHR, 1.71 [95% CI, 0.84-3.47]; P = .14). There were no significant differences in outcome by CPV status of the 63 CPG set., Conclusions and Relevance: This cohort study identified a group of patients with embryonal rhabdomyosarcoma who had a particularly poor outcome. Other important clinical findings included that individuals with TP53 had poor outcomes independent of second malignant neoplasms and that patients with fusion-negative rhabdomyosarcoma who harbored a CPV had outcomes comparable to patients with fusion-positive rhabdomyosarcoma. These findings suggest that germline CPV testing may aid in clinical prognosis and should be considered in prospective risk-based clinical trials.

Purpose: Osteosarcoma research advancement requires enhanced data integration across different modalities and sources. Current osteosarcoma research, encompassing clinical, genomic, protein, and tissue imaging data, is hindered by the siloed landscape of data generation and storage., Materials and Methods: Clinical, molecular profiling, and tissue imaging data for 573 patients with pediatric osteosarcoma were collected from four public and institutional sources. A common data model incorporating standardized terminology was created to facilitate the transformation, integration, and load of source data into a relational database. On the basis of this database, a data commons accompanied by a user-friendly web portal was developed, enabling various data exploration and analytics functions., Results: The Osteosarcoma Explorer (OSE) was released to the public in 2021. Leveraging a comprehensive and harmonized data set on the backend, the OSE offers a wide range of functions, including Cohort Discovery, Patient Dashboard, Image Visualization, and Online Analysis. Since its initial release, the OSE has experienced an increasing utilization by the osteosarcoma research community and provided solid, continuous user support. To our knowledge, the OSE is the largest (N = 573) and most comprehensive research data commons for pediatric osteosarcoma, a rare disease. This project demonstrates an effective framework for data integration and data commons development that can be readily applied to other projects sharing similar goals., Conclusion: The OSE offers an online exploration and analysis platform for integrated clinical, molecular profiling, and tissue imaging data of osteosarcoma. Its underlying data model, database, and web framework support continuous expansion onto new data modalities and sources.

Background: Ewing sarcoma (EWS) is an aggressive sarcoma with few treatment options for patients with relapsed disease. Cyclin-dependent kinase 4 (CDK4) is a genomic vulnerability in EWS that is synergistic with IGF-1R inhibition in preclinical studies. We present the results of a phase 2 study combining palbociclib (CDK4/6 inhibitor) with ganitumab (IGF-1R monoclonal antibody) for patients with relapsed EWS., Patients and Methods: This open-label, non-randomized, phase 2 trial enrolled patients ≥12 years with relapsed EWS. All patients had molecular confirmation of EWS and RECIST measurable disease. Patients initially received palbociclib 125 mg orally on Days 1-21 and ganitumab 18 mg/kg intravenously on Days 1 and 15 of a 28-day cycle. The primary endpoints were objective response (complete or partial) per RECIST and toxicity by CTCAE. An exact one-stage design required ≥4 responders out of 15 to evaluate an alternative hypothesis of 40% response rate against a null of 10%. The study was closed following enrollment of the 10th patient due to discontinuation of ganitumab supply., Results: Ten evaluable patients enrolled [median age 25.7 years (range 12.3-40.1)]. The median duration of therapy was 2.5 months (range 0.9-10.8). There were no complete or partial responders. Three of 10 patients had stable disease for >4 cycles and 2 had stable disease at completion of planned therapy or study closure. Six-month progression-free survival was 30% (95% CI 1.6%-58.4%). Two patients had cycle 1 hematologic dose-limiting toxicities (DLTs) triggering palbociclib dose reduction to 100 mg daily for 21 days. Two subsequent patients had cycle 1 hematologic DLTs at the reduced dose. Eighty percent of patients had grade 3/4 AEs, including neutropenia (n = 8), white blood cell decreased (n = 7), and thrombocytopenia (n = 5). Serum total IGF-1 significantly increased (p = 0.013) and ctDNA decreased during the first cycle., Conclusions: This combination lacks adequate therapeutic activity for further study, though a subset of patients had prolonged stable disease., (© 2023 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Purpose: Novel biomarkers are needed to differentiate outcomes in intermediate-risk rhabdomyosarcoma (IR RMS). We sought to evaluate strategies for identifying circulating tumor DNA (ctDNA) in IR RMS and to determine whether ctDNA detection before therapy is associated with outcome., Patients and Methods: Pretreatment serum and tumor samples were available from 124 patients with newly diagnosed IR RMS from the Children's Oncology Group biorepository, including 75 patients with fusion-negative rhabdomyosarcoma (FN-RMS) and 49 with fusion-positive rhabdomyosarcoma (FP-RMS) disease. We used ultralow passage whole-genome sequencing to detect copy number alterations and a new custom sequencing assay, Rhabdo-Seq, to detect rearrangements and single-nucleotide variants., Results: We found that ultralow passage whole-genome sequencing was a method applicable to ctDNA detection in all patients with FN-RMS and that ctDNA was detectable in 13 of 75 serum samples (17%). However, the use of Rhabdo-Seq in FN-RMS samples also identified single-nucleotide variants, such as MYOD1 L122R , previously associated with prognosis. Identification of pathognomonic translocations between PAX3 or PAX7 and FOXO1 by Rhabdo-Seq was the best method for measuring ctDNA in FP-RMS and detected ctDNA in 27 of 49 cases (55%). Patients with FN-RMS with detectable ctDNA at diagnosis had significantly worse outcomes than patients without detectable ctDNA (event-free survival, 33.3% v 68.9%; P = .0028; overall survival, 33.3% v 83.2%; P < .0001) as did patients with FP-RMS (event-free survival, 37% v 70%; P = .045; overall survival, 39.2% v 75%; P = .023). In multivariable analysis, ctDNA was independently associated with worse prognosis in FN-RMS but not in the smaller FP-RMS cohort., Conclusion: Our study demonstrates that baseline ctDNA detection is feasible and is prognostic in IR RMS.

Purpose: Treatment options for recurrent or refractory Ewing's sarcoma (ES) are limited. Vigil is a novel autologous tumor cell therapy expressing bi-shRNA furin/GMCSF plasmid, which previously demonstrated monotherapy activity in advanced ES. Herein we report safety and evidence of benefit to Vigil for ES as potential treatment., Patients and Methods: In this pilot trial, eligible patients with recurrent or refractory ES who failed initial standard-of-care therapy received treatment with temozolomide (TEM) 100 mg/m2/day oral and irinotecan (IRI) 50 mg/m2/day oral, Days 1 to 5, in combination with Vigil (1 × 106-107 cells/mL/day intradermal, Day 15), every 21 days (Vigil/TEM/IRI). Objective response rate (ORR) by RECIST v1.1, progression-free survival (PFS), and overall survival (OS) were assessed. Circulating tumor (ct) DNA analysis was done by patient-specific droplet digital PCR on baseline and serially collected on-treatment samples., Results: Eight of 10 enrolled patients were evaluable for safety and efficacy (mean age 24.6; 12.6-46.1 years old); 2 did not receive Vigil. Seven of 8 patients previously received TEM/IRI. No Vigil-related adverse events were reported. Common ≥Grade 3 chemotherapy-related toxicity included neutropenia (50%) and thrombocytopenia (38%). We observed two partial response patients by RECIST; both showed histologic complete response without additional cancer therapy. Median PFS was 8.2 months (95% confidence interval, 4.3-NA). Five patients showed stable disease or better for ≥6 months. Patient-specific EWS/FLI1 ctDNA was detectable in all 8 evaluable patients at baseline. Changes in ctDNA levels corresponded to changes in disease burden., Conclusions: Results demonstrated safety of combination Vigil/TEM/IRI., (©2023 The Authors; Published by the American Association for Cancer Research.)

Purpose: Monoclonal antibodies directed against insulin-like growth factor-1 receptor (IGF-1R) have shown activity in patients with relapsed Ewing sarcoma. The primary objective of Children's Oncology Group trial AEWS1221 was to determine if the addition of the IGF-1R monoclonal antibody ganitumab to interval-compressed chemotherapy improves event-free survival (EFS) in patients with newly diagnosed metastatic Ewing sarcoma., Methods: Patients were randomly assigned 1:1 at enrollment to standard arm (interval-compressed vincristine/doxorubicin/cyclophosphamide alternating once every 2 weeks with ifosfamide/etoposide = VDC/IE) or to experimental arm (VDC/IE with ganitumab at cycle starts and as monotherapy once every 3 weeks for 6 months after conventional therapy). A planned sample size of 300 patients was projected to provide 81% power to detect an EFS hazard ratio of 0.67 or smaller for the experimental arm compared with the standard arm with a one-sided α of .025., Results: Two hundred ninety-eight eligible patients enrolled (148 in standard arm; 150 in experimental arm). The 3-year EFS estimates were 37.4% (95% CI, 29.3 to 45.5) for the standard arm and 39.1% (95% CI, 31.3 to 46.7) for the experimental arm (stratified EFS-event hazard ratio for experimental arm 1.00; 95% CI, 0.76 to 1.33; 1-sided, P = .50). The 3-year overall survival estimates were 59.5% (95% CI, 50.8 to 67.3) for the standard arm and 56.7% (95% CI, 48.3 to 64.2) for the experimental arm. More cases of pneumonitis after radiation involving thoracic fields and nominally higher rates of febrile neutropenia and ALT elevation were reported on the experimental arm., Conclusion: Ganitumab added to interval-compressed chemotherapy did not significantly reduce the risk of EFS event in patients with newly diagnosed metastatic Ewing sarcoma, with outcomes similar to prior trials without IGF-1R inhibition or interval compression. The addition of ganitumab may be associated with increased toxicity.

Purpose: Osteosarcoma risk stratification, on the basis of the presence of metastatic disease at diagnosis and histologic response to chemotherapy, has remained unchanged for four decades, does not include genomic features, and has not facilitated treatment advances. We report on the genomic features of advanced osteosarcoma and provide evidence that genomic alterations can be used for risk stratification., Materials and Methods: In a primary analytic patient cohort, 113 tumor and 69 normal samples from 92 patients with high-grade osteosarcoma were sequenced with OncoPanel, a targeted next-generation sequencing assay. In this primary cohort, we assessed the genomic landscape of advanced disease and evaluated the correlation between recurrent genomic events and outcome. We assessed whether prognostic associations identified in the primary cohort were maintained in a validation cohort of 86 patients with localized osteosarcoma tested with MSK-IMPACT., Results: In the primary cohort, 3-year overall survival (OS) was 65%. Metastatic disease, present in 33% of patients at diagnosis, was associated with poor OS ( P = .04). The most frequently altered genes in the primary cohort were TP 53, RB1, MYC, CCNE1, CCND3, CDKN2A/B, and ATRX . Mutational signature 3 was present in 28% of samples. MYC amplification was associated with a worse 3-year OS in both the primary cohort ( P = .015) and the validation cohort ( P = .012)., Conclusion: The most frequently occurring genomic events in advanced osteosarcoma were similar to those described in prior reports. MYC amplification, detected with clinical targeted next-generation sequencing panel tests, is associated with poorer outcomes in two independent cohorts.

Background: Ewing sarcoma (EWS) is an aggressive sarcoma with no validated molecular biomarkers. We aimed to determine the frequency of STAG2 protein loss by immunohistochemistry (IHC) and whether loss of expression is associated with outcome., Methods: We performed a retrospective cohort study of patients with EWS enrolled to Children's Oncology Group studies. We obtained unstained slides from 235 patients and DNA for sequencing from 75 patients. STAG2 expression was tested for association with clinical features and survival was estimated using Kaplan-Meier methods with log-rank tests., Results: In total, 155 cases passed quality control for STAG2 IHC. STAG2 expression in 20/155 cases could not be categorised with the limited available tissue, leaving 135 patients with definitive STAG2 IHC. In localised and metastatic disease, STAG2 was lost in 29/108 and 6/27 cases, respectively. Among patients with IHC and sequencing, 0/17 STAG2 expressing cases had STAG2 mutations, and 2/7 cases with STAG2 loss had STAG2 mutations. Among patients with localised disease, 5-year event-free survival was 54% (95% CI 34-70%) and 75% (95% CI 63-84%) for patients with STAG2 loss vs. expression (P = 0.0034)., Conclusion: STAG2 loss of expression is identified in a population of patients without identifiable STAG2 mutations and carries a poor prognosis., (© 2022. The Author(s).)

The advent of dose intensified interval compressed therapy has improved event-free survival for patients with localized Ewing sarcoma (EwS) to 78% at 5 years. However, nearly a quarter of patients with localized tumors and 60-80% of patients with metastatic tumors suffer relapse and die of disease. In addition, those who survive are often left with debilitating late effects. Clinical features aside from stage have proven inadequate to meaningfully classify patients for risk-stratified therapy. Therefore, there is a critical need to develop approaches to risk stratify patients with EwS based on molecular features. Over the past decade, new technology has enabled the study of multiple molecular biomarkers in EwS. Preliminary evidence requiring validation supports copy number changes, and loss of function mutations in tumor suppressor genes as biomarkers of outcome in EwS. Initial studies of circulating tumor DNA demonstrated that diagnostic ctDNA burden and ctDNA clearance during induction are also associated with outcome. In addition, fusion partner should be a pre-requisite for enrollment on EwS clinical trials, and the fusion type and structure require further study to determine prognostic impact. These emerging biomarkers represent a new horizon in our understanding of disease risk and will enable future efforts to develop risk-adapted treatment., (© 2022. The Author(s).)

Purpose: The utility of circulating tumor DNA (ctDNA) analyses has not been established in the risk stratification of Wilms tumor (WT). We evaluated the detection of ctDNA and selected risk markers in the serum and urine of patients with WT and compared findings with those of matched diagnostic tumor samples., Patients and Methods: Fifty of 395 children with stage III or IV WT enrolled on Children's Oncology Group trial AREN0533 had banked pretreatment serum, urine, and tumor available. Next-generation sequencing was used to detect ctDNA. Copy-number changes in 1q, 16q, and 1p, and single-nucleotide variants in serum and urine were compared with tumor biopsy data. Event-free survival (EFS) was compared between patients with and without ctDNA detection., Results: ctDNA was detected in the serum of 41/50 (82%) and in the urine in 13/50 (26%) patients. Agreement between serum ctDNA detection and tumor sequencing results was as follows: 77% for 1q gain, 88% for 16q deletions, and 70% for 1p deletions, with ĸ-coefficients of 0.56, 0.74, and 0.29, respectively. Sequencing also demonstrated that single-nucleotide variants detected in tumors could be identified in the ctDNA. There was a trend toward worse EFS in patients with ctDNA detected in the serum (4-year EFS 80% v 100%, P = .14)., Conclusion: ctDNA demonstrates promise as an easily accessible prognostic biomarker with potential to detect tumor heterogeneity. The observed trend toward more favorable outcome in patients with undetectable ctDNA requires validation. ctDNA profiling should be further explored as a noninvasive diagnostic and prognostic tool in the risk-adapted treatment of patients with WT.

Serrated polyps are pathological neoplastic lesions in the colon with subtle gross morphology leading to underreporting during colonoscopy. While detection rates are increasing in average-risk adult screening colonoscopy, the rate of detection during pediatric colonoscopy is unknown. Serrated polyposis syndrome is characterized by the presence of multiple serrated polyps in the colon and an increased risk of developing colorectal cancer. Cancer prevention relies on early recognition, endoscopic clearance of all polyps > 5 mm, and continued interval surveillance or prophylactic colectomy. We report the diagnosis and management of serrated polyposis syndrome in a young adolescent patient and highlight the subtle features of serrated polyps that may go unrecognized leading to underreporting in childhood., Competing Interests: The authors report no conflicts of interest., (Copyright © 2022 by European Society for European Society for Pediatric Gastroenterology, Hepatology, and Nutrition and North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition.)

To evaluate the clinical impact of molecular tumor profiling (MTP) with targeted sequencing panel tests, pediatric patients with extracranial solid tumors were enrolled in a prospective observational cohort study at 12 institutions. In the 345-patient analytical population, median age at diagnosis was 12 years (range 0-27.5); 298 patients (86%) had 1 or more alterations with potential for impact on care. Genomic alterations with diagnostic, prognostic or therapeutic significance were present in 61, 16 and 65% of patients, respectively. After return of the results, impact on care included 17 patients with a clarified diagnostic classification and 240 patients with an MTP result that could be used to select molecularly targeted therapy matched to identified alterations (MTT). Of the 29 patients who received MTT, 24% had an objective response or experienced durable clinical benefit; all but 1 of these patients received targeted therapy matched to a gene fusion. Of the diagnostic variants identified in 209 patients, 77% were gene fusions. MTP with targeted panel tests that includes fusion detection has a substantial clinical impact for young patients with solid tumors., (© 2022. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Somatic gene translocations are key to making an accurate diagnosis in many cancers including many pediatric sarcomas. Currently available molecular diagnostic approaches to identifying somatic pathognomonic translocations have limitations such as minimal multiplexing, high cost, complex computational requirements, or slow turnaround times. We sought to develop a new fusion-detection assay optimized to mitigate these challenges. To accomplish this goal, we developed a highly sensitive multiplexed digital PCR-based approach that can identify the gene partners of multiple somatic fusion transcripts. This assay was validated for specificity with cell lines and synthetized DNA fragments. Assay sensitivity was optimized using a tiered amplification approach for fusion detection from low input and/or degraded RNA. The assay was then tested for the potential application of fusion detection from FFPE tissue and liquid biopsy samples. We found that this multiplexed PCR approach was able to accurately identify the presence of seven different targeted fusion transcripts with a turnaround time of 1 to 2 days. The addition of a tiered amplification step allowed the detection of targeted fusions from as little as 1 pg of RNA input. We also identified fusions from as little as two unstained slides of FFPE tumor biopsy tissue, from circulating tumor cells collected from tumor-bearing mice, and from liquid biopsy samples from patients with known fusion-positive cancers. We also demonstrated that the assay could be easily adapted for additional fusion targets. In summary, this novel assay detects multiple somatic fusion partners in biologic samples with low tumor content and low-quality RNA in less than two days. The assay is inexpensive and could be applied to surgical and liquid biopsies, particularly in places with inadequate resources for more expensive and expertise-dependent assays such as next-generation sequencing., (© 2022. The Author(s).)

Purpose: We sought to determine whether the detection of circulating tumor DNA (ctDNA) in samples of patients undergoing chemotherapy for advanced leiomyosarcoma (LMS) is associated with objective response or survival., Experimental Design: Using ultra-low-passage whole-genome sequencing (ULP-WGS) of plasma cell-free DNA from patients treated on a prospective clinical trial, we tested whether detection of ctDNA evaluated prior to the start of therapy and after two cycles of chemotherapy was associated with treatment response and outcome. Associations between detection of ctDNA and pathologic measures of disease burden were evaluated., Results: We found that ctDNA was detectable by ULP-WGS in 49% patients prior to treatment and in 24.6% patients after two cycles of chemotherapy. Detection of pretreatment ctDNA was significantly associated with a lower overall survival [HR, 1.55; 95% confidence interval (CI), 1.03-2.31; P = 0.03] and a significantly lower likelihood of objective response [odds ratio (OR), 0.21; 95% CI, 0.06-0.59; P = 0.005]. After two cycles of chemotherapy, patients who continued to have detectable levels of ctDNA experienced a significantly worse overall survival (HR, 1.77; 95% CI, 1-3.14; P = 0.05) and were unlikely to experience an objective response (OR, 0.05; 95% CI, 0-0.39; P = 0.001)., Conclusions: Our results demonstrate that detection of ctDNA is associated with outcome and objective response to chemotherapy in patients with advanced LMS. These results suggest that liquid biopsy assays could be used to inform treatment decisions by recognizing patients who are likely and unlikely to benefit from chemotherapy. See related commentary by Kasper and Wilky, p. 2480., (©2022 The Authors; Published by the American Association for Cancer Research.)

More knowledge is needed regarding germline predisposition to Ewing sarcoma to inform biological investigation and clinical practice. Here, we evaluated the enrichment of pathogenic germline variants in Ewing sarcoma relative to other pediatric sarcoma subtypes, as well as patterns of inheritance of these variants. We carried out European-focused and pan-ancestry case-control analyses to screen for enrichment of pathogenic germline variants in 141 established cancer predisposition genes in 1,147 individuals with pediatric sarcoma diagnoses (226 Ewing sarcoma, 438 osteosarcoma, 180 rhabdomyosarcoma, and 303 other sarcoma) relative to identically processed cancer-free control individuals. Findings in Ewing sarcoma were validated with an additional cohort of 430 individuals, and a subset of 301 Ewing sarcoma parent-proband trios was analyzed for inheritance patterns of identified pathogenic variants. A distinct pattern of pathogenic germline variants was seen in Ewing sarcoma relative to other sarcoma subtypes. FANCC was the only gene with an enrichment signal for heterozygous pathogenic variants in the European Ewing sarcoma discovery cohort (three individuals, OR 12.6, 95% CI 3.0-43.2, p = 0.003, FDR = 0.40). This enrichment in FANCC heterozygous pathogenic variants was again observed in the European Ewing sarcoma validation cohort (three individuals, OR 7.0, 95% CI 1.7-23.6, p = 0.014), representing a broader importance of genes involved in DNA damage repair, which were also nominally enriched in individuals with Ewing sarcoma. Pathogenic variants in DNA damage repair genes were acquired through autosomal inheritance. Our study provides new insight into germline risk factors contributing to Ewing sarcoma pathogenesis., Competing Interests: Declaration of interests R.G. has equity in Google, Microsoft, Amazon, Apple, Moderna, Pfizer, and Vertex Pharmaceuticals. J.K.'s spouse has received consulting fees from ROME Therapeutics, Foundation Medicine, Inc., NanoString Technologies, EMD Millipore Sigma, Pfizer, and Tekla Capital; is a founder and has equity in ROME Therapeutics, PanTher Therapeutics, and TellBio, Inc.; and receives research support from ACD-Biotechne, PureTech Health LLC, and Ribon Therapeutics. J.D.S. is co-founder and shareholder in ItRunsInMyFamily.com and is co-founder, shareholder, and employed by Peel Therapeutics, Inc. E.M.V.A. holds consulting roles with Tango Therapeutics, Genome Medical, Genomic Life, Enara Bio, Janssen, and Manifold Bio; he receives research support from Bristol-Myers Squibb and Novartis; he has equity in Tango Therapeutics, Genome Medical, Genomic Life, Syapse, Enara Bio, Manifold Bio, and Microsoft; he has received travel reimbursement from Roche and Genentech; and he has filed institutional patents on chromatin mutations, immunotherapy response, and methods for clinical interpretation. The other authors declare no competing interests., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Purpose: Leiomyosarcoma (LMS) is a neoplasm characterized by smooth muscle differentiation, complex copy-number alterations, tumor suppressor loss, and the absence of recurrent driver mutations. Clinical management for advanced disease relies on the use of empiric cytotoxic chemotherapy with limited activity, and novel targeted therapies supported by preclinical research on LMS biology are urgently needed. A lack of fidelity of established LMS cell lines to their mesenchymal neoplasm of origin has limited translational understanding of this disease, and few other preclinical models have been established. Here, we characterize patient-derived xenograft (PDX) models of LMS, assessing fidelity to their tumors of origin and performing preclinical evaluation of candidate therapies., Experimental Design: We implanted 49 LMS surgical samples into immunocompromised mice. Engrafting tumors were characterized by histology, targeted next-generation sequencing, RNA sequencing, and ultra-low passage whole-genome sequencing. Candidate therapies were selected based on prior evidence of pathway activation or high-throughput dynamic BH3 profiling., Results: We show that LMS PDX maintain the histologic appearance, copy-number alterations, and transcriptional program of their parental tumors across multiple xenograft passages. Transcriptionally, LMS PDX cocluster with paired LMS patient-derived samples and differ primarily in host-related immunologic and microenvironment signatures. We identify susceptibility of LMS PDX to transcriptional cyclin-dependent kinase (CDK) inhibition, which disrupts an E2F-driven oncogenic transcriptional program and inhibits tumor growth., Conclusions: Our results establish LMS PDX as valuable preclinical models and identify strategies to discover novel vulnerabilities in this disease. These data support the clinical assessment of transcriptional CDK inhibitors as a therapeutic strategy for patients with LMS., (©2022 American Association for Cancer Research.)

Purpose: Molecular tumor profiling is becoming a routine part of clinical cancer care, typically involving tumor-only panel testing without matched germline. We hypothesized that integrated germline sequencing could improve clinical interpretation and enhance the identification of germline variants with significant hereditary risks., Materials and Methods: Tumors from pediatric patients with high-risk, extracranial solid malignancies were sequenced with a targeted panel of cancer-associated genes. Later, germline DNA was analyzed for a subset of these genes. We performed a post hoc analysis to identify how an integrated analysis of tumor and germline data would improve clinical interpretation., Results: One hundred sixty participants with both tumor-only and germline sequencing reports were eligible for this analysis. Germline sequencing identified 38 pathogenic or likely pathogenic variants among 35 (22%) patients. Twenty-five (66%) of these were included in the tumor sequencing report. The remaining germline pathogenic or likely pathogenic variants were single-nucleotide variants filtered out of tumor-only analysis because of population frequency or copy-number variation masked by additional copy-number changes in the tumor. In tumor-only sequencing, 308 of 434 (71%) single-nucleotide variants reported were present in the germline, including 31% with suggested clinical utility. Finally, we provide further evidence that the variant allele fraction from tumor-only sequencing is insufficient to differentiate somatic from germline events., Conclusion: A paired approach to analyzing tumor and germline sequencing data would be expected to improve the efficiency and accuracy of distinguishing somatic mutations and germline variants, thereby facilitating the process of variant curation and therapeutic interpretation for somatic reports, as well as the identification of variants associated with germline cancer predisposition., Competing Interests: Alanna J. Church Honoraria: The Jackson Laboratory Consulting or Advisory Role: AlphaSights, The Jackson Laboratory, Bayer Travel, Accommodations, Expenses: Bayer Laura B. Corson Employment: Sema4 Stock and Other Ownership Interests: Alnylam, Inovio Pharmaceuticals, Agios Consulting or Advisory Role: Biomatics Patents, Royalties, Other Intellectual Property: Patent from work done at H3 Biomedicine before 2016 Brennan Decker Employment: Foundation Medicine Stock and Other Ownership Interests: Avidea Technologies, Roche Consulting or Advisory Role: Foundation Medicine, Avidea Technologies Catherine M. Clinton Employment: Helix OpCo LLC Mark A. Applebaum Consulting or Advisory Role: Fennec Pharma Rochelle Bagatell Uncompensated Relationships: Ymabs Therapeutics Inc Steven G. DuBois Consulting or Advisory Role: Bayer, Amgen Research Funding: Merck (Inst), Roche/Genentech (Inst), Lilly (Inst), Curis (Inst), Loxo (Inst), BMS (Inst), Eisai (Inst), Pfizer (Inst), Turning Point Therapeutics (Inst), Bayer (Inst), Salarius Pharmaceuticals (Inst) Travel, Accommodations, Expenses: Roche/Genentech, Salarius Pharmaceuticals Uncompensated Relationships: Ymabs Therapeutics Inc Julia L. Glade-Bender Research Funding: Eisai (Inst), Lilly (Inst), Loxo (Inst), Roche/Genentech (Inst), Bayer (Inst) Patents, Royalties, Other Intellectual Property: Patent on a T lympboblastic lymphoma cell line, CUTLL1 Travel, Accommodations, Expenses: Amgen (Inst) Uncompensated Relationships: SpringWorks Therapeutics, Bristol Myers Squibb, Merck, Eisai Open Payments Link: https://openpaymentsdata.cms.gov/physician/708514 AeRang Kim Research Funding: Esai (Inst); AstraZeneca (Inst); Oncternal (Inst); Ascentage (Inst); BioAlta (Inst). Theodore W. Laetsch Consulting or Advisory Role: Novartis, Bayer, Cellectis, Aptitude Health, Clinical Education Alliance, Deciphera, Jumo Health, Massive Bio, Med Learning Group, Medscape, Physicans' Education Resource, Y-mAbs Therapeutics Research Funding: Pfizer (Inst), Novartis (Inst), Bayer (Inst), AbbVie (Inst), Amgen (Inst), Atara Biotherapeutics (Inst), Bristol Myers Squibb (Inst), Lilly (Inst), Epizyme (Inst), GlaxoSmithKline (Inst), Janssen (Inst), Jubilant Pharmaceuticals (Inst), Novella Clinical (Inst), Servier (Inst), Foundation Medicine (Inst), Merck Sharp & Dohme (Inst) Margaret E. Macy Stock and Other Ownership Interests: Johnson & Johnson, GE Healthcare, Varian Medical Systems Consulting or Advisory Role: Ymabs Therapeutics Inc Research Funding: Bayer (Inst), Ignyta (Inst), Roche (Inst), Lilly (Inst), Merck (Inst), Oncternal Therapeutics Inc (Inst), AbbVie (Inst), Jubilant DraxImage (Inst), Actuate Therapeutics (Inst) Patents, Royalties, Other Intellectual Property: Patent for non-invasive methods of leukemia cell detection with MRI/MRS—Patent No. 8894975 Luke Maese Honoraria: Jazz Pharmaceuticals Consulting or Advisory Role: Jazz Pharmaceuticals Amit J. Sabnis Consulting or Advisory Role: Cardinal Health Joshua D. Schiffman Employment: PEEL Therapeutics Leadership: PEEL Therapeutics Stock and Other Ownership Interests: ItRunsInMyFamily.com, PEEL Therapeutics Honoraria: Affymetrix Consulting or Advisory Role: N-of-One, Fabric Genomics Samuel L. Volchenboum Stock and Other Ownership Interests: Litmus Health Consulting or Advisory Role: Accordant Travel, Accommodations, Expenses: Sanford Health Daniel A. Weiser Consulting or Advisory Role: Illumina Radiopharmaceuticals Jonathan A. Nowak Research Funding: NanoString Technologies, Illumina Katherine A. Janeway Honoraria: Foundation Medicine, Takeda Consulting or Advisory Role: Bayer, Ipsen Travel, Accommodations, Expenses: Bayer Brian D. Crompton Employment: Acceleron Pharma (I) Stock and Other Ownership Interests: Acceleron Pharma (I) Research Funding: Gradalis Junne Kamihara Stock and Other Ownership Interests: PanTher Therapeutics (I), ROME Therapeutics (I), TellBio (I) Honoraria: Pfizer (I), NanoString Technologies (I), Foundation Medicine (I), Ikena Oncology (I) Consulting or Advisory Role: ROME Therapeutics (I), Third Rock Ventures (I), Tekla Capital Management (I) Research Funding: PureTech (I), Ribon Therapeutics (I), ACD Biotechne (I) Patents, Royalties, Other Intellectual Property: Patent on drug delivery device licensed to PanTher Therapeutics (I), Patents on Repeat RNA biomarkers and therapeutics licensed to Rome Therapeutics (I), Patents on Circulating Tumor Cell Biomarkers Licensed to TellBio Inc (I) No other potential conflicts of interest were reported. Alanna J. Church Honoraria: The Jackson Laboratory Consulting or Advisory Role: AlphaSights, The Jackson Laboratory, Bayer Travel, Accommodations, Expenses: Bayer Laura B. Corson Employment: Sema4 Stock and Other Ownership Interests: Alnylam, Inovio Pharmaceuticals, Agios Consulting or Advisory Role: Biomatics Patents, Royalties, Other Intellectual Property: Patent from work done at H3 Biomedicine before 2016 Brennan Decker Employment: Foundation Medicine Stock and Other Ownership Interests: Avidea Technologies, Roche Consulting or Advisory Role: Foundation Medicine, Avidea Technologies Catherine M. Clinton Employment: Helix OpCo LLC Mark A. Applebaum Consulting or Advisory Role: Fennec Pharma Rochelle Bagatell Uncompensated Relationships: Ymabs Therapeutics Inc Steven G. DuBois Consulting or Advisory Role: Bayer, Amgen Research Funding: Merck (Inst), Roche/Genentech (Inst), Lilly (Inst), Curis (Inst), Loxo (Inst), BMS (Inst), Eisai (Inst), Pfizer (Inst), Turning Point Therapeutics (Inst), Bayer (Inst), Salarius Pharmaceuticals (Inst) Travel, Accommodations, Expenses: Roche/Genentech, Salarius Pharmaceuticals Uncompensated Relationships: Ymabs Therapeutics Inc Julia L. Glade-Bender Research Funding: Eisai (Inst), Lilly (Inst), Loxo (Inst), Roche/Genentech (Inst), Bayer (Inst) Patents, Royalties, Other Intellectual Property: Patent on a T lympboblastic lymphoma cell line, CUTLL1 Travel, Accommodations, Expenses: Amgen (Inst) Uncompensated Relationships: SpringWorks Therapeutics, Bristol Myers Squibb, Merck, Eisai Open Payments Link: https://openpaymentsdata.cms.gov/physician/708514 AeRang Kim Research Funding: Esai (Inst); AstraZeneca (Inst); Oncternal (Inst); Ascentage (Inst); BioAlta (Inst). Theodore W. Laetsch Consulting or Advisory Role: Novartis, Bayer, Cellectis, Aptitude Health, Clinical Education Alliance, Deciphera, Jumo Health, Massive Bio, Med Learning Group, Medscape, Physicans' Education Resource, Y-mAbs Therapeutics Research Funding: Pfizer (Inst), Novartis (Inst), Bayer (Inst), AbbVie (Inst), Amgen (Inst), Atara Biotherapeutics (Inst), Bristol Myers Squibb (Inst), Lilly (Inst), Epizyme (Inst), GlaxoSmithKline (Inst), Janssen (Inst), Jubilant Pharmaceuticals (Inst), Novella Clinical (Inst), Servier (Inst), Foundation Medicine (Inst), Merck Sharp & Dohme (Inst) Margaret E. Macy Stock and Other Ownership Interests: Johnson & Johnson, GE Healthcare, Varian Medical Systems Consulting or Advisory Role: Ymabs Therapeutics Inc Research Funding: Bayer (Inst), Ignyta (Inst), Roche (Inst), Lilly (Inst), Merck (Inst), Oncternal Therapeutics Inc (Inst), AbbVie (Inst), Jubilant DraxImage (Inst), Actuate Therapeutics (Inst) Patents, Royalties, Other Intellectual Property: Patent for non-invasive methods of leukemia cell detection with MRI/MRS—Patent No. 8894975 Luke Maese Honoraria: Jazz Pharmaceuticals Consulting or Advisory Role: Jazz Pharmaceuticals Amit J. Sabnis Consulting or Advisory Role: Cardinal Health Joshua D. Schiffman Employment: PEEL Therapeutics Leadership: PEEL Therapeutics Stock and Other Ownership Interests: ItRunsInMyFamily.com, PEEL Therapeutics Honoraria: Affymetrix Consulting or Advisory Role: N-of-One, Fabric Genomics Samuel L. Volchenboum Stock and Other Ownership Interests: Litmus Health Consulting or Advisory Role: Accordant Travel, Accommodations, Expenses: Sanford Health Daniel A. Weiser Consulting or Advisory Role: Illumina Radiopharmaceuticals Jonathan A. Nowak Research Funding: NanoString Technologies, Illumina Katherine A. Janeway Honoraria: Foundation Medicine, Takeda Consulting or Advisory Role: Bayer, Ipsen Travel, Accommodations, Expenses: Bayer Brian D. Crompton Employment: Acceleron Pharma (I) Stock and Other Ownership Interests: Acceleron Pharma (I) Research Funding: Gradalis Junne Kamihara Stock and Other Ownership Interests: PanTher Therapeutics (I), ROME Therapeutics (I), TellBio (I) Honoraria: Pfizer (I), NanoString Technologies (I), Foundation Medicine (I), Ikena Oncology (I) Consulting or Advisory Role: ROME Therapeutics (I), Third Rock Ventures (I), Tekla Capital Management (I) Research Funding: PureTech (I), Ribon Therapeutics (I), ACD Biotechne (I) Patents, Royalties, Other Intellectual Property: Patent on drug delivery device licensed to PanTher Therapeutics (I), Patents on Repeat RNA biomarkers and therapeutics licensed to Rome Therapeutics (I), Patents on Circulating Tumor Cell Biomarkers Licensed to TellBio Inc (I) No other potential conflicts of interest were reported., (© 2021 by American Society of Clinical Oncology.)

Context.—: Molecular diagnostics play an increasing role in the diagnosis of Ewing sarcoma. The type of molecular testing used in clinical practice has been poorly described., Objective.—: To describe patterns of translocation testing for newly diagnosed Ewing sarcoma., Design.—: Children's Oncology Group (COG) trial AEWS1221 was a phase III randomized trial enrolling patients with newly diagnosed metastatic Ewing sarcoma from 2014 to 2019. Patients were required to have a histologic diagnosis of Ewing sarcoma, but translocation testing was not required. Sites provided types and results of any molecular diagnostics performed., Results.—: Data from 305 enrolled patients were available. The most common type of molecular testing was fluorescence in situ hybridization (FISH) performed on the primary tumor (236 of 305 patients; 77.4%), with positive testing for an EWSR1 or FUS translocation in 211 (89.4%). Reverse transcription-polymerase chain reaction (RT-PCR) on the primary tumor was performed in 61 of 305 patients (20%), with positive results in 48 of 61 patients (78.7%). Next-generation sequencing was reported in 7 patients for the primary tumor and in 3 patients for metastatic sites. For all types of testing on either primary or metastatic tumor, 16 of 305 patients (5.2%) had no reported translocation testing. When evaluating all results from all testing, 44 of 305 patients (14.4%) lacked documentation of an abnormality consistent with a molecular diagnosis of Ewing sarcoma., Conclusions.—: COG sites enrolling in a Ewing sarcoma trial have high rates of testing by FISH or PCR. A small proportion of patients have no translocation testing on either primary or metastatic sites. Next-generation sequencing techniques are not yet commonly used in this context.

The core cohesin subunit STAG2 is recurrently mutated in Ewing sarcoma but its biological role is less clear. Here, we demonstrate that cohesin complexes containing STAG2 occupy enhancer and polycomb repressive complex (PRC2)-marked regulatory regions. Genetic suppression of STAG2 leads to a compensatory increase in cohesin-STAG1 complexes, but not in enhancer-rich regions, and results in reprogramming of cis-chromatin interactions. Strikingly, in STAG2 knockout cells the oncogenic genetic program driven by the fusion transcription factor EWS/FLI1 was highly perturbed, in part due to altered enhancer-promoter contacts. Moreover, loss of STAG2 also disrupted PRC2-mediated regulation of gene expression. Combined, these transcriptional changes converged to modulate EWS/FLI1, migratory, and neurodevelopmental programs. Finally, consistent with clinical observations, functional studies revealed that loss of STAG2 enhances the metastatic potential of Ewing sarcoma xenografts. Our findings demonstrate that STAG2 mutations can alter chromatin architecture and transcriptional programs to promote an aggressive cancer phenotype., Competing Interests: Declaration of interests None of the authors declare a conflict of interest for this project but report the following relationships. N.V.D. is a current employee of Genentech, Inc., a member of the Roche Group. R.A.Y. is a founder and shareholder of Syros Pharmaceuticals, Camp4 Therapeutics, Omega Therapeutics, and Dewpoint Therapeutics. M.J.A. has financial interests in Monitor Biotechnologies (formerly known as Beacon Genomics). K.S. receives grant funding as part of the DFCI/Novartis Drug Discovery Program, consults for and has stock options in Auron Therapeutics, and consulted for AstraZeneca and Kronos Bio. B.D.C. receives research funding from Gradalis for an unrelated project, and his spouse was previously employed by Shire and Mersana and currently works for Acceleron., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Introduction: Tissue from pediatric solid tumors is in high demand for use in high-impact research studies, making the allocation of tissue from an anatomic pathology laboratory challenging. We designed, implemented, and assessed an interdepartmental process to optimize tissue allocation of pediatric solid tumors for both clinical care and research., Methods: Oncologists, pathologists, surgeons, interventional radiologists, pathology technical staff, and clinical research coordinators participated in the workflow design. Procedures were created to address patient identification and consent, prioritization of protocols, electronic communication of requests, tissue preparation, and distribution. Pathologists were surveyed about the value of the new workflow., Results: Over a 5-year period, 644 pediatric solid tumor patients consented to one or more studies requesting archival or fresh tissue. Patients had a variety of tumor types, with many rare and singular diagnoses. Sixty-seven percent of 1768 research requests were fulfilled. Requests for archival tissue were fulfilled at a significantly higher rate than those for fresh tissue (P > .001), and requests from resection specimens were fulfilled at a significantly higher rate than those from biopsies (P > .0001). In an anonymous survey, seven of seven pathologists reported that the process had improved since the introduction of the electronic communication model., Conclusions: A collaborative and informed model for tissue allocation is successful in distributing archival and fresh tissue for clinical research studies. Our workflows and policies have gained pathologists' approval and streamlined our processes. As clinical and research programs evolve, a thoughtful tissue allocation process will facilitate ongoing research., (© 2020 Wiley Periodicals, Inc.)

Liquid biopsies are new technologies that allow cancer profiling of tumor fragments found in body fluids, such as peripheral blood, collected noninvasively from patients with malignancies. These assays are increasingly valuable in clinical oncology practice as prognostic biomarkers, as guides for therapy selection, for treatment monitoring, and for early detection of disease progression and relapse. However, application of these assays to rare cancers, such as pediatric and adult sarcomas, have lagged. In this article, we review the technical challenges of applying liquid biopsy technologies to sarcomas, provide an update on progress in the field, describe common pitfalls in interpreting liquid biopsy data, and discuss the intersection of sarcoma clinical care and commercial assays emerging on the horizon.

Liquid biopsies encompass a number of new technologies designed to derive tumor data through the minimally invasive sampling of an accessible body fluid. These technologies remain early in their clinical development, and applications for patients with osteosarcoma are actively under investigation. In this chapter, we outline the current state of liquid biopsy technologies as they apply to cancer generally and osteosarcoma specifically, focusing on assays that detect and profile circulating tumor DNA (ctDNA), microRNAs (miRNA), and circulating tumor cells (CTCs). At present, ctDNA assays are the most mature, with multiple assays demonstrating the feasibility of detecting and quantifying ctDNA from blood samples of patients with osteosarcoma. Initial studies show that ctDNA can be detected in the majority of patients with osteosarcoma and that the detection and level of ctDNA correlates with a worse prognosis. Profiling of ctDNA can also identify specific somatic events that may have prognostic relevance, such as 8q gain in osteosarcoma. miRNAs are stable RNAs that regulate gene expression and are known to be dysregulated in cancer, and patterns of miRNA expression have been evaluated in multiple studies of patients with osteosarcoma. While studies have identified differential expression of many miRNAs in osteosarcomas compared to healthy controls, a consensus set of prognostic miRNAs has yet to be definitively validated. Recent studies have also demonstrated the feasibility of capturing CTCs in patients with osteosarcoma. The development of assays that quantify and profile CTCs for use as prognostic biomarkers or tools for biologic discovery is still in development. However, CTC technology holds incredible promise given the potential to perform multi-omic approaches in single cancer cells to understand osteosarcoma heterogeneity and tumor evolution. The next step required to move liquid biopsy technologies closer to helping patients will be wide-scale collection of patient samples from large prospective studies.

Patients who are diagnosed with osteosarcoma (OS) today receive the same therapy that patients have received over the last 4 decades. Extensive efforts to identify more effective or less toxic regimens have proved disappointing. As we enter a postgenomic era in which we now recognize OS not as a cancer of mutations but as one defined by p53 loss, chromosomal complexity, copy number alteration, and profound heterogeneity, emerging threads of discovery leave many hopeful that an improving understanding of biology will drive discoveries that improve clinical care. Under the organization of the Bone Tumor Biology Committee of the Children's Oncology Group, a team of clinicians and scientists sought to define the state of the science and to identify questions that, if answered, have the greatest potential to drive fundamental clinical advances. Having discussed these questions in a series of meetings, each led by invited experts, we distilled these conversations into a series of seven Provocative Questions. These include questions about the molecular events that trigger oncogenesis, the genomic and epigenomic drivers of disease, the biology of lung metastasis, research models that best predict clinical outcomes, and processes for translating findings into clinical trials. Here, we briefly present each Provocative Question, review the current scientific evidence, note the immediate opportunities, and speculate on the impact that answered questions might have on the field. We do so with an intent to provide a framework around which investigators can build programs and collaborations to tackle the hardest problems and to establish research priorities for those developing policies and providing funding., (© 2019 American Cancer Society.)

Purpose: Ewing sarcoma is an aggressive solid tumor malignancy of childhood. Although current treatment regimens cure approximately 70% of patients with localized disease, they are ineffective for most patients with metastases or relapse. New treatment combinations are necessary for these patients., Experimental Design: Ewing sarcoma cells are dependent on focal adhesion kinase (FAK) for growth. To identify candidate treatment combinations for Ewing sarcoma, we performed a small-molecule library screen to identify compounds synergistic with FAK inhibitors in impairing Ewing cell growth. The activity of a top-scoring class of compounds was then validated across multiple Ewing cell lines in vitro and in multiple xenograft models of Ewing sarcoma., Results: Numerous Aurora kinase inhibitors scored as synergistic with FAK inhibition in this screen. We found that Aurora kinase B inhibitors were synergistic across a larger range of concentrations than Aurora kinase A inhibitors when combined with FAK inhibitors in multiple Ewing cell lines. The combination of AZD-1152, an Aurora kinase B-selective inhibitor, and PF-562271 or VS-4718, FAK-selective inhibitors, induced apoptosis in Ewing sarcoma cells at concentrations that had minimal effects on survival when cells were treated with either drug alone. We also found that the combination significantly impaired tumor progression in multiple xenograft models of Ewing sarcoma., Conclusions: FAK and Aurora kinase B inhibitors synergistically impair Ewing sarcoma cell viability and significantly inhibit tumor progression. This study provides preclinical support for the consideration of a clinical trial testing the safety and efficacy of this combination for patients with Ewing sarcoma., (©2019 American Association for Cancer Research.)

Circulating tumor DNA can be detected in the blood and body fluids of patients using ultrasensitive technologies, which have the potential to improve cancer diagnosis, risk stratification, noninvasive tumor profiling, and tracking of treatment response and disease recurrence. As we begin to apply "liquid biopsy" strategies in children with cancer, it is important to tailor our efforts to the unique genomic features of these tumors and address the technical and logistical challenges of integrating biomarker testing. This article reviews the literature demonstrating the feasibility of applying liquid biopsy to pediatric solid malignancies and suggests new directions for future studies., (© 2019 Wiley Periodicals, Inc.)

Renal medullary carcinoma (RMC) is a rare and deadly kidney cancer in patients of African descent with sickle cell trait. We have developed faithful patient-derived RMC models and using whole-genome sequencing, we identified loss-of-function intronic fusion events in one SMARCB1 allele with concurrent loss of the other allele. Biochemical and functional characterization of these models revealed that RMC requires the loss of SMARCB1 for survival. Through integration of RNAi and CRISPR-Cas9 loss-of-function genetic screens and a small-molecule screen, we found that the ubiquitin-proteasome system (UPS) was essential in RMC. Inhibition of the UPS caused a G2/M arrest due to constitutive accumulation of cyclin B1. These observations extend across cancers that harbor SMARCB1 loss, which also require expression of the E2 ubiquitin-conjugating enzyme, UBE2C . Our studies identify a synthetic lethal relationship between SMARCB1 -deficient cancers and reliance on the UPS which provides the foundation for a mechanism-informed clinical trial with proteasome inhibitors., Competing Interests: AH, YT, JW, WK, BK, MD, GK, GS, TH, JL, XY, MT, MG, AS, RD, AW, BM, KL, PK, AT, CC, CC, AC, BC, KJ, BV, DS, OG, SS, DR, PG, SC, EM, CR, KL, JB No competing interests declared, PB, RB is a consultant for Novartis (Cambridge, MA), PC is an adviser for Pfizer, Inc (Groton, CT), CK is a Scientific Founder, member of the Board of Director, Scientific Advisory Board member, Shareholder, and Consultant for Foghorn Therapeutics, Inc (Cambridge, MA). Disclosure information for CK is also found at: http://www.kadochlab.org, WH is a consultant for Thermo Fisher, Aju IB, MPM Capital and Paraxel. W.C.H. is a founder and shareholder and serves on the scientific advisory board of KSQ Therapeutics, (© 2019, Hong et al.)

Purpose: Increasing use of genomic tumor profiling may blur the line between research and clinical care. We aimed to describe research participants' perspectives on the purpose of genomic tumor profiling research in pediatric oncology., Methods: We surveyed 45 participants (response rate 85%) in a pilot study of genomic profiling in pediatric solid tumors at four academic cancer centers following return of sequencing results. We defined understanding according to a one-item ("basic") definition (recognizing that the primary purpose was not to improve the patient's treatment) and a four-item ("comprehensive") definition (primary purpose was not to improve patient's treatment; primary purpose was to improve treatment of future patients; there may not be direct medical benefit; most likely result of participation was not increased likelihood of cure)., Results: Sixty-eight percent of respondents (30/44) demonstrated basic understanding of the study purpose; 55% (24/44) demonstrated comprehensive understanding. Understanding was more frequently seen in those with higher education and greater genetic knowledge according to basic (81% vs 50%, p=0.05; and 82% vs 46%, p=0.03, respectively) and comprehensive definitions (73% vs 28%, p=0.01; 71% vs 23%, p=0.01). Ninety-three percent of respondents who believed the primary purpose was to improve the patient's care simultaneously stated that the research also aimed to benefit future patients., Conclusions: Most participants in pediatric tumor profiling research understand that the primary goal of this research is to improve care for future patients, but many express dual goals when participating in sequencing research. Some populations demonstrate increased rates of misunderstanding. Nuanced participant views suggest further work is needed to assess and improve participant understanding, particularly as tumor sequencing moves beyond research into clinical practice.

Purpose: Leiomyosarcoma (LMS) is a soft tissue sarcoma characterized by multiple copy number alterations (CNAs) and without common recurrent single nucleotide variants. We evaluated the feasibility of detecting circulating tumor DNA (ctDNA) with next-generation sequencing in a cohort of patients with LMS whose tumor burden ranged from no evidence of disease to metastatic progressive disease., Patients and Methods: Cell-free DNA in plasma samples and paired genomic DNA from resected tumors were evaluated from patients with LMS by ultra-low passage whole genome sequencing (ULP-WGS). Sequencing reads were aligned to the human genome and CNAs identified in cell-free DNA and tumor DNA by ichorCNA software to determine the presence of ctDNA. Clinical data were reviewed to assess disease burden and clinicopathologic features., Results: We identified LMS ctDNA in eleven of sixteen patients (69%) with disease progression and total tumor burden over 5 cm. Sixteen patients with stable disease or low disease burden at the time of blood draw were found to have no detectable ctDNA. Higher ctDNA fraction of total cell-free DNA was associated with increasing tumor size and disease progression. Conserved CNAs were found between primary tumors and ctDNA in each case, and recurrent CNAs were found across LMS samples. ctDNA levels declined following resection of progressive disease in one case and became detectable upon disease relapse in another individual patient., Conclusion: These results suggest that ctDNA, assayed by a widely available sequencing approach, may be useful as a biomarker for a subset of uterine and extrauterine LMS. Higher levels of ctDNA correlate with tumor size and disease progression. Liquid biopsies may assist in guiding treatment decisions, monitoring response to systemic therapy, surveying for disease recurrence and differentiating benign and malignant smooth muscle tumors., Competing Interests: AUTHORS’ DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST Matthew L. Hemming No relationship to disclose Kelly S. Klega No relationship to disclose Justin Rhoades No relationship to disclose Gavin Ha Patent application: WO2017161175A1 Kate E. Acker No relationship to disclose Jessica L. Andersen No relationship to disclose Anwesha Nag No relationship to disclose Aaron R. Thorner No relationship to disclose Chandrajit P. Raut No relationship to disclose Suzanne George Consulting or Advisory Role: Blueprint Medicines, Deciphera Pharmaceuticals Research Funding: Bayer, Pfizer, Novartis Brian D. Crompton No relationship to disclose

Multi-agent chemotherapeutic regimes remain the cornerstone treatment for Ewing sarcoma, the second most common bone malignancy diagnosed in pediatric and young adolescent populations. We have reached a therapeutic ceiling with conventional cytotoxic agents, highlighting the need to adopt novel approaches that specifically target the drivers of Ewing sarcoma oncogenesis. As KDM1A/ l ysine- s pecific d emethylase 1 (LSD1) is highly expressed in Ewing sarcoma cell lines and tumors, with elevated expression levels associated with worse overall survival ( P = 0.033), this study has examined biomarkers of sensitivity and mechanisms of cytotoxicity to targeted KDM1A inhibition using SP-2509 (reversible KDM1A inhibitor). We report, that innate resistance to SP-2509 was not observed in our Ewing sarcoma cell line cohort ( n = 17; IC 50 range, 81 -1,593 nmol/L), in contrast resistance to the next-generation KDM1A irreversible inhibitor GSK-LSD1 was observed across multiple cell lines (IC 50 > 300 μmol/L). Although TP53/STAG2/CDKN2A status and basal KDM1A mRNA and protein levels did not correlate with SP-2509 response, induction of KDM1B following SP-2509 treatment was strongly associated with SP-2509 hypersensitivity. We show that the transcriptional profile driven by SP-2509 strongly mirrors KDM1A genetic depletion. Mechanistically, RNA-seq analysis revealed that SP-2509 imparts robust apoptosis through engagement of the endoplasmic reticulum stress pathway. In addition, ETS1/HIST1H2BM were specifically induced/repressed, respectively following SP-2509 treatment only in our hypersensitive cell lines. Together, our findings provide key insights into the mechanisms of SP-2509 cytotoxicity as well as biomarkers that can be used to predict KDM1A inhibitor sensitivity in Ewing sarcoma. Mol Cancer Ther; 17(9); 1902-16. ©2018 AACR ., (©2018 American Association for Cancer Research.)

Background: New prognostic markers are needed to identify patients with Ewing sarcoma (EWS) and osteosarcoma unlikely to benefit from standard therapy. We describe the incidence and association with outcome of circulating tumour DNA (ctDNA) using next-generation sequencing (NGS) assays., Methods: A NGS hybrid capture assay and an ultra-low-pass whole-genome sequencing assay were used to detect ctDNA in banked plasma from patients with EWS and osteosarcoma, respectively. Patients were coded as positive or negative for ctDNA and tested for association with clinical features and outcome., Results: The analytic cohort included 94 patients with EWS (82% from initial diagnosis) and 72 patients with primary localised osteosarcoma (100% from initial diagnosis). ctDNA was detectable in 53% and 57% of newly diagnosed patients with EWS and osteosarcoma, respectively. Among patients with newly diagnosed localised EWS, detectable ctDNA was associated with inferior 3-year event-free survival (48.6% vs. 82.1%; p = 0.006) and overall survival (79.8% vs. 92.6%; p = 0.01). In both EWS and osteosarcoma, risk of event and death increased with ctDNA levels., Conclusions: NGS assays agnostic of primary tumour sequencing results detect ctDNA in half of the plasma samples from patients with newly diagnosed EWS and osteosarcoma. Detectable ctDNA is associated with inferior outcomes.

Objective: Liquid biopsies are being rapidly used in adult cancers as new biomarkers of disease. Circulating tumor DNA (ctDNA) levels have been reported to be proportional to disease burden, correlate with treatment response, and predict relapse. However, little is known about how frequently ctDNA is detectable in pediatric patients with solid tumors. Therefore, we developed a next-generation sequencing approach to detect and quantify ctDNA in the blood of patients with the most common pediatric solid tumors., Methods: Detection of ctDNA requires assays sensitive to somatic events typically observed in the cancer type being studied. In pediatric solid tumors, structural variants are more common than recurrent point mutations. We adapted an ultralow passage whole-genome sequencing approach to capture copy number variants and a hybrid capture sequencing assay to detect translocations in liquid biopsy samples from pediatric patients., Results: Copy number changes seen by ultralow passage whole-genome sequencing enabled detection of ctDNA in patients with osteosarcoma, neuroblastoma, alveolar rhabdomyosarcoma, and Wilms tumor. In Ewing sarcoma, detection of the EWSR1 translocation was a more sensitive approach. For patients with samples collected at multiple time points, changes in ctDNA levels corresponded to treatment response. We also found that disease-specific genomic biomarkers of prognosis were detectable in ctDNA., Conclusion: This study demonstrates that liquid biopsy approaches that detect somatic structural variants are well suited to pediatric solid tumors. We show that children with the most common solid tumor malignancies have detectable levels of ctDNA, which may be used to track disease response and identify genomic subclassifiers of disease. Efforts to profile larger collections of clinically annotated specimens are under way to validate the clinical use of these assays., Competing Interests: AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST The following represents disclosure information provided by authors of this manuscript. All relationships are considered compensated. Relationships are self-held unless noted. I = Immediate Family Member, Inst = My Institution. Relationships may not relate to the subject matter of this manuscript. For more information about ASCO's conflict of interest policy, please refer to www.asco.org/rwc or ascopubs.org/po/author-center. Kelly Klega No relationship to disclose Alma Imamovic-Tuco No relationship to disclose Gavin Ha No relationship to disclose Andrea N. Clapp No relationship to disclose Stephanie Meyer No relationship to disclose Abigail Ward No relationship to disclose Catherine Clinton No relationship to disclose Anwesha Nag No relationship to disclose Eliezer Van Allen Stock and Other Ownership Interests: Syapse, Tango Therapeutics, Genome Medical Consulting or Advisory Role: Syapse, Roche, Third Rock Ventures, Takeda, Novartis, Genome Medical, InVitae Speakers' Bureau: Illumina Research Funding: Bristol-Myers Squibb, Novartis Elizabeth Mullen No relationship to disclose Steven G. DuBois Honoraria: Loxo Consulting or Advisory Role: Loxo Research Funding: Millennium (Inst), Merck (Inst), Novartis (Inst), Roche/Genentech (Inst), Eli Lilly (Inst), Curis (Inst), Loxo (Inst) Travel, Accommodations, Expenses: Loxo, Roche/Genentech Katherine Janeway No relationship to disclose Matthew Meyerson Stock and Other Ownership Interests: OrigiMed Consulting or Advisory Role: OrigiMed Research Funding: Bayer (Inst) Patents, Royalties, Other Intellectual Property: Patent on EGFR mutations for lung cancer diagnosis Aaron R. Thorner No relationship to disclose Brian D. Crompton Employment: Mersana (I), Shire (I) Stock and Other Ownership Interests: Mersana (I), Shire (I)

Objectives: Liquid biopsy technologies allow non-invasive tumor profiling for patients with solid tumor malignancies by sequencing circulating tumor DNA. These studies may be useful in risk-stratification, monitoring for relapse, and understanding tumor evolution. The quality of DNA obtained for these studies is improved when blood samples are collected in tubes that stabilizing white blood cells (WBC). However, ongoing germline research in pediatric oncology generally requires obtaining blood samples in EDTA tubes, which do not contain a WBC-stabilizing preservative. In this study, we explored whether blood samples collected in WBC-stabilizing tubes could be used for both liquid biopsy and germline studies simultaneously, minimizing blood collection volumes for pediatric patients., Methods: Blood was simultaneously collected from three patients in both EDTA and Streck Cell-Free DNA BCT® tubes. Germline DNA was extracted from all blood samples and subjected to whole-exome sequencing and microarray profiling., Results: Quality control metrics of DNA quality, sequencing library preperation and whole-exome sequencing alignment were virtually identical regardless of the sample collection method. There was no discernable difference in patterns of variant calling for paired samples by either whole-exome sequencing or microarray analysis., Conclusion: Our study demonstrates that high-quality genomic studies may be performed from germline DNA obtained in Streck tubes. Therefore, these tubes may be used to simultaneously obtain samples for both liquid biopsy and germline studies in pediatric patients when the volume of blood available for research studies may be limited.

Background: Genomic tumor profiling (GTP) plays an important role in the care of many adult cancer patients. Its role in pediatric oncology is still evolving, with only a subset of patients currently expected to receive clinically significant results. Little is known about perspectives of pediatric oncology patients/parents on GTP., Procedure: We surveyed individuals who previously underwent GTP through the iCat (Individualized Cancer Therapy) pilot study of molecular profiling in children with relapsed, refractory, and high-risk solid tumors at four pediatric cancer centers. Following return of profiling results, a cross-sectional survey was offered to the patient, if he or she was 18 years or older at enrollment, or parent, if he or she was under 18 years of age. Forty-five surveys (85% response) were completed., Results: Eighty-nine percent (39/44) of respondents reported hoping participation would help find cures for future patients, while 59% (26/44) hoped it would increase their/their child's chance of cure. Most had few concerns about GTP, but 12% (5/43) worried they would learn their/their child's cancer was less treatable or more aggressive than previously thought. Sixty-four percent (29/45) reported feeling their participation had helped others and 44% (20/45) felt they had helped themselves/their own child, despite only one substudy subject receiving targeted therapy matched to GTP findings. Fifty-four percent (21/39) wished to receive all available profiling data, including findings unrelated to cancer and of unclear significance., Conclusions: Participants in pediatric GTP research perceive benefits of GTP to themselves and others, but expectations of personal benefits of GTP may exceed actual positive impact. These issues warrant consideration during consent discussions about GTP research participation., (© 2016 Wiley Periodicals, Inc.)

Identifying therapeutic targets in rare cancers remains challenging due to the paucity of established models to perform preclinical studies. As a proof-of-concept, we developed a patient-derived cancer cell line, CLF-PED-015-T, from a paediatric patient with a rare undifferentiated sarcoma. Here, we confirm that this cell line recapitulates the histology and harbours the majority of the somatic genetic alterations found in a metastatic lesion isolated at first relapse. We then perform pooled CRISPR-Cas9 and RNAi loss-of-function screens and a small-molecule screen focused on druggable cancer targets. Integrating these three complementary and orthogonal methods, we identify CDK4 and XPO1 as potential therapeutic targets in this cancer, which has no known alterations in these genes. These observations establish an approach that integrates new patient-derived models, functional genomics and chemical screens to facilitate the discovery of targets in rare cancers.

Sarcomas are a rare subgroup of pediatric cancers comprised of a variety of bone and soft-tissue tumors. While significant advances have been made in improving outcomes of patients with localized pediatric sarcomas since the addition of systemic chemotherapy to local control many decades ago, outcomes for patients with metastatic and relapsed sarcoma remain poor with few novel therapeutics identified to date. With the advent of new technologies to study cancer genomes, transcriptomes and epigenomes, our understanding of sarcoma biology has improved tremendously in a relatively short period of time. However, much remains to be accomplished in this arena especially with regard to translating all of this new knowledge to the bedside. To this end, a meeting was convened in Philadelphia, PA, on April 18, 2015 sponsored by the QuadW foundation, Children's Oncology Group and CureSearch for Children's Cancer that brought together sarcoma clinicians and scientists from North America to review the current state of pediatric sarcoma biology and ongoing/planned genomics based clinical trials in an effort to identify and bridge knowledge gaps that continue to exist at present. At the conclusion of the workshop, three key objectives that would significantly further our understanding of sarcoma were identified and a proposal was put forward to develop an all-encompassing pediatric sarcoma biology protocol that would address these specific needs. This review summarizes the proceedings of the workshop., (Copyright © 2016. Published by Elsevier Inc.)

Importance: Pediatric cancers represent a unique case with respect to cancer genomics and precision medicine, as the mutation frequency is low, and targeted therapies are less available. Consequently, it is unknown whether clinical sequencing can be of benefit., Objective: To assess the feasibility of identifying actionable alterations and making individualized cancer therapy (iCat) recommendations in pediatric patients with extracranial solid tumors., Design, Setting, and Participants: Clinical sequencing study at 4 academic medical centers enrolling patients between September 5, 2012, and November 19, 2013, with 1 year of clinical follow-up. Participants were 30 years or younger with high-risk, recurrent, or refractory extracranial solid tumors. The data analysis was performed October 28, 2014., Interventions: Tumor profiling performed on archived clinically acquired specimens consisted of mutation detection by a Sequenom assay or targeted next-generation sequencing and copy number assessment by array comparative genomic hybridization. Results were reviewed by a multidisciplinary expert panel, and iCat recommendations were made if an actionable alteration was present, and an appropriate drug was available., Main Outcomes and Measures: Feasibility was assessed using a 2-stage design based on the proportion of patients with recommendations., Results: Of 100 participants (60 male; median [range] age, 13.4 [0.8-29.8] years), profiling was technically successful in 89 (89% [95% CI, 83%-95%]). Median (range) follow-up was 6.8 (2.0-23.6) months. Overall, 31 (31% [95% CI, 23%-41%]) patients received an iCat recommendation and 3 received matched therapy. The most common actionable alterations leading to an iCat recommendation were cancer-associated signaling pathway gene mutations (n = 10) and copy number alterations in MYC/MYCN (n = 6) and cell cycle genes (n = 11). Additional alterations with implications for clinical care but not resulting in iCat recommendations were identified, including mutations indicating the possible presence of a cancer predisposition syndrome and translocations suggesting a change in diagnosis. In total, 43 (43% [95% CI, 33%-53%]) participants had results with potential clinical significance., Conclusions and Relevance: A multi-institution clinical genomics study in pediatric oncology is feasible and a substantial proportion of relapsed or refractory pediatric solid tumors have actionable alterations., Trial Registration: clinicaltrials.gov Identifier: NCT01853345.

Unlabelled: Pediatric Ewing sarcoma is characterized by the expression of chimeric fusions of EWS and ETS family transcription factors, representing a paradigm for studying cancers driven by transcription factor rearrangements. In this study, we describe the somatic landscape of pediatric Ewing sarcoma. These tumors are among the most genetically normal cancers characterized to date, with only EWS-ETS rearrangements identified in the majority of tumors. STAG2 loss, however, is present in more than 15% of Ewing sarcoma tumors; occurs by point mutation, rearrangement, and likely nongenetic mechanisms; and is associated with disease dissemination. Perhaps the most striking finding is the paucity of mutations in immediately targetable signal transduction pathways, highlighting the need for new therapeutic approaches to target EWS-ETS fusions in this disease., Significance: We performed next-generation sequencing of Ewing sarcoma, a pediatric cancer involving bone, characterized by expression of EWS-ETS fusions. We found remarkably few mutations. However, we discovered that loss of STAG2 expression occurs in 15% of tumors and is associated with metastatic disease, suggesting a potential genetic vulnerability in Ewing sarcoma., (©2014 American Association for Cancer Research.)

Limited progress has been made in the treatment of advanced-stage pediatric solid tumors despite the accelerated pace of cancer discovery over the last decade. Tyrosine kinase inhibition is one tractable therapeutic modality for treating human malignancy. However, little is known about the kinases critical to the development or maintenance of many pediatric solid tumors such as Ewing sarcoma. Using a fluorescent, bead-based technology to profile activated tyrosine kinases, we identified focal adhesion kinase (FAK, PTK2) as a candidate target in Ewing sarcoma. FAK is a tyrosine kinase critical for cellular adhesion, growth, and survival. As such, it is a compelling target for cancer-based therapy. In this study, we have shown that FAK is highly phosphorylated in primary Ewing sarcoma tumor samples and that downregulation of FAK by short hairpin RNA and treatment with a FAK-selective kinase inhibitor, PF-562271, impaired growth and colony formation in Ewing sarcoma cell lines. Moreover, treatment of Ewing sarcoma cell lines with PF-562271 induced apoptosis and led to downregulation of AKT/mTOR and CAS activity. Finally, we showed that small-molecule inhibition of FAK attenuated Ewing sarcoma tumor growth in vivo. With FAK inhibitors currently in early-phase clinical trials for adult malignancies, these findings may bear immediate relevance to patients with Ewing sarcoma.

Background: Approximately one-third of patients with osteosarcoma who have a complete response to their initial treatment can be expected to relapse. It is important to define what host, tumor, or treatment characteristics determine outcome after relapse. We present findings in 59 patients treated at our institution from 1974 to 1996 who have relapsed one or more times after their initial response., Methods: Host and tumor characteristics at diagnosis and relapse, therapeutic interventions and survival outcomes were determined from examination of medical records and a follow-up questionnaire., Results: Of the 59 patients, 37 initially presented with localized disease of the extremity, 11 with localized non-extremity disease, and 11 with metastatic disease. This report focuses on those with localized disease of the extremity. For these patients, median time from original diagnosis to first recurrence was 14 months. Median survival after first recurrence was 31 months. The median post initial relapse survival was the same for patients whose first relapse occurred before or after 14 months from original diagnosis. Seventeen of 29 patients with systemic metastasis at first recurrence had complete removal of their disease and had a median post-op survival of 2.5 years, while the remaining 12 patients with no surgery, had a median survival of 2 years. Of the 37 patients who presented with primary disease only in the extremities and relapsed: 31 died (2 more than 6 years from first recurrence) and 6 are alive from 6 to 24 years from first recurrence (5 without disease and 1 with disease). Three of the five disease-free survivors had three or more relapses., Conclusion: With a long follow-up time, we found 15% of patients with relapsed osteosarcoma who originally presented with localized disease in the extremity are alive with no evidence of disease at 10 years from first recurrence (Kaplan-Meier estimate). Even patients with multiple relapses may have long-term disease-free survival after salvage therapy. Chemotherapy and time to first recurrence were unrelated to survival after relapse in this study. Complete surgical removal of metastatic disease may be important for long-term survival.