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PURPOSE: Liquid biopsies can be used to investigate tumor-derived DNA, circulating in the cell-free DNA (cfDNA) pool in blood. We aimed to develop a droplet digital polymerase chain reaction (ddPCR) assay detecting hypermethylation of tumor suppressor gene RASSF1A as a simple standard test to detect various pediatric tumor types in small volume blood samples and to evaluate this test for monitoring treatment response of patients with high-risk neuroblastoma. METHODS: We developed a ddPCR assay to sensitively detect tumor-derived hypermethylated RASSF1A DNA in liquid biopsies. We tested this assay in plasma of 96 patients with neuroblastoma, renal tumors, rhabdomyosarcoma, or Hodgkin lymphoma at diagnosis and in cerebrospinal fluid of four patients with brain tumors. We evaluated the presence of hypermethylated RASSF1A in plasma samples during treatment and follow-up in 47 patients with neuroblastoma treated according to high-risk protocol and correlated results with blood mRNA–based and bone marrow mRNA–based minimal residual disease detection and clinical outcomes. RESULTS: The total cfDNA level was significantly higher in patients with metastatic neuroblastoma and nephroblastoma compared with healthy adult and pediatric controls. Hypermethylated RASSF1A was present in 41 of 42 patients with metastatic neuroblastoma and in all patients with nephroblastoma, with the median percentage of 69% and 21% of total RASSF1A , respectively. Hypermethylated RASSF1A levels decreased during therapy and recurred at relapse. CONCLUSION: Our findings demonstrate the value of ddPCR-based detection of hypermethylated RASSF1A as a circulating molecular tumor marker in neuroblastoma. Our preliminary investigation of RASSF1A hypermethylation detection in circulating cfDNA of other pediatric tumor entities demonstrates potential as a pan-tumor marker, but requires investigation in larger cohorts to evaluate its use and limitations. The circulating tumor marker hypermethylated RASSF1A can be detected in the plasma of pediatric patients with solid tumors [ABSTRACT FROM AUTHOR]

Purpose: Total cell-free DNA (cfDNA) and tumor-derived cfDNA (ctDNA) can be used to study tumor-derived genetic aberrations. We analyzed the diagnostic and prognostic potential of cfDNA and ctDNA, obtained from pediatric patients with rhabdomyosarcoma., Methods: cfDNA was isolated from diagnostic plasma samples from 57 patients enrolled in the EpSSG RMS2005 study. To study the diagnostic potential, shallow whole genome sequencing (shWGS) and cell-free reduced representation bisulphite sequencing (cfRRBS) were performed in a subset of samples and all samples were tested using droplet digital polymerase chain reaction to detect methylated RASSF1A ( RASSF1A- M). Correlation with outcome was studied by combining cfDNA RASSF1A- M detection with analysis of our rhabdomyosarcoma-specific RNA panel in paired cellular blood and bone marrow fractions and survival analysis in 56 patients., Results: At diagnosis, ctDNA was detected in 16 of 30 and 24 of 26 patients using shallow whole genome sequencing and cfRRBS, respectively. Furthermore, 21 of 25 samples were correctly classified as embryonal by cfRRBS. RASSF1A -M was detected in 21 of 57 patients. The presence of RASSF1A -M was significantly correlated with poor outcome (the 5-year event-free survival [EFS] rate was 46.2% for 21 RASSF1A -M ‒ positive patients, compared with 84.9% for 36 RASSF1A -M ‒ negative patients [ P < .001]). RASSF1A -M positivity had the highest prognostic effect among patients with metastatic disease. Patients both negative for RASSF1A -M and the rhabdomyosarcoma-specific RNA panel (28 of 56 patients) had excellent outcome (5-year EFS 92.9%), while double-positive patients (11/56) had poor outcome (5-year EFS 13.6%, P < .001)., Conclusion: Analyzing ctDNA at diagnosis using various techniques is feasible in pediatric rhabdomyosarcoma and has potential for clinical use. Measuring RASSF1A- M in plasma at initial diagnosis correlated significantly with outcome, particularly when combined with paired analysis of blood and bone marrow using a rhabdomyosarcoma-specific RNA panel.

Purpose: Outcome for patients with metastatic rhabdomyosarcoma (RMS) is poor. This study presents the results of the MTS 2008 study with a pooled analysis including patients from the concurrent BERNIE study., Patients and Methods: In MTS 2008, patients with metastatic RMS received four cycles of ifosfamide, vincristine, and actinomycin D (IVA) plus doxorubicin, five cycles of IVA, and 12 cycles of maintenance chemotherapy (low-dose cyclophosphamide and vinorelbine). The BERNIE study randomly assigned patients to the addition or not of bevacizumab to the same chemotherapy. Local therapy (surgery/radiotherapy) was given to the primary tumor and all metastatic sites when feasible., Results: MTS 2008 included 270 patients (median age, 9.6 years; range, 0.07-20.8 years). With a median follow-up of 50.3 months, 3-year event-free survival (EFS) and overall survival (OS) were 34.9% (95% CI, 29.1 to 40.8) and 47.9% (95% CI, 41.6 to 53.9), respectively. In pooled analyses on 372 patients with a median follow-up of 55.2 months, 3-year EFS and OS were 35.5% (95% CI, 30.4 to 40.6) and 49.3% (95% CI, 43.9 to 54.5), respectively. Patients with ≤ 2 Oberlin risk factors (ORFs) had better outcome than those with ≥ 3 ORFs: 3-year EFS was 46.1% versus 12.5% ( P < .0001) and 3-year OS 60.0% versus 26.0% ( P < .0001). Induction chemotherapy and maintenance appeared tolerable; however, about two third of patients needed dose adjustments during maintenance., Conclusion: Outcome remains poor for patients with metastatic RMS and multiple ORFs. Because of the design of the studies, it was not possible to determine whether the intensive induction regimen and/or the addition of maintenance treatment resulted in apparent improvement of outcome compared with historical cohorts. Further studies, with novel treatment approaches are urgently needed, to improve outcome for the group of patients with adverse prognostic factors.

Purpose: To evaluate the clinical significance of indeterminate pulmonary nodules at diagnosis (defined as ≤ 4 pulmonary nodules < 5 mm or 1 nodule measuring ≥ 5 and < 10 mm) in patients with pediatric rhabdomyosarcoma (RMS)., Patients and Methods: We selected patients with supposed nonmetastatic RMS treated in large pediatric oncology centers in the United Kingdom, France, Italy, and the Netherlands, who were enrolled in the European Soft Tissue Sarcoma Study Group (E pSSG) RMS 2005 study. Patients included in the current study received a diagnosis between September 2005 and December 2013, and had chest computed tomography scans available for review that were done at time of diagnosis. Local radiologists were asked to review the chest computed tomography scans for the presence of pulmonary nodules and to record their findings on a standardized case report form. In the E pSSG RMS 2005 Study, patients with indeterminate pulmonary nodules were treated identically to patients without pulmonary nodules, enabling us to compare event-free survival and overall survival between groups by log-rank test., Results: In total, 316 patients were included; 67 patients (21.2%) had indeterminate pulmonary nodules on imaging and 249 patients (78.8%) had no pulmonary nodules evident at diagnosis. Median follow-up for survivors (n = 258) was 75.1 months; respective 5-year event-free survival and overall survival rates (95% CI) were 77.0% (64.8% to 85.5%) and 82.0% (69.7% to 89.6%) for patients with indeterminate nodules and 73.2% (67.1% to 78.3%) and 80.8% (75.1% to 85.3%) for patients without nodules at diagnosis ( P = .68 and .76, respectively)., Conclusion: Our study demonstrated that indeterminate pulmonary nodules at diagnosis do not affect outcome in patients with otherwise localized RMS. There is no need to biopsy or upstage patients with RMS who have indeterminate pulmonary nodules at diagnosis.

Purpose: Previous studies suggest poor outcome in children with relapsed rhabdomyosarcoma (RMS). A better understanding is needed of which patients can be salvaged after first relapse., Patients and Methods: The analysis included children with nonmetastatic RMS and embryonal sarcoma enrolled onto the International Society of Paediatric Oncology (SIOP) Malignant Mesenchymal Tumor (MMT) 84, 89, and 95 studies who relapsed after achieving complete local control with primary therapy. All patients included in the analysis had follow-up for ≥ 3.0 years after the last event. The clinical features, initial treatment characteristics, and features of the relapse were correlated with survival in univariate and multivariate analyses., Results: In all, 474 eligible patients were identified for the study. At ≥ 3.0 years from the last event, 176 (37%) were alive ("cured"). In a full-model multivariate analysis, the factors identified at first relapse that most strongly associated with poor outcome were metastatic relapse (odds ratio [OR], 4.19; 95% CI, 2.0 to 8.5), prior radiotherapy treatment (OR, 3.64; 95% CI, 2.1 to 6.4), initial tumor size > 5 cm (OR, 2.53; 95% CI, 1.5 to 4.1), and time of relapse < 18 months from diagnosis (OR, 2.20; 95% CI, 1.3 to 3.6). Unfavorable primary disease site, nodal involvement at diagnosis, alveolar histology, and previous three- or six-drug chemotherapy were also independently associated with poor outcome. To estimate chance of cure for individual patients, a nomogram was developed, which allowed for weighting of these significant factors., Conclusion: Some children with relapsed RMS remain curable. It is now possible to estimate the chance of salvage for individual children to direct therapy appropriately toward cure, use of experimental therapies, and/or palliation.