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Supplemental Table 1. Association of clinical features with BM micrometastatic cell burden (CD99+CD45- percent) in flow cytometry cohort. Supplemental Table 2. Total CD99+CD45- percent burden in Ewing sarcoma patients with clinically evident BM metastasis (N=6).

Purpose: Flow cytometry and RT-PCR can detect occult Ewing sarcoma cells in the blood and bone marrow. These techniques were used to evaluate the prognostic significance of micrometastatic disease in Ewing sarcoma.Experimental Design: Newly diagnosed patients with Ewing sarcoma were enrolled on two prospective multicenter studies. In the flow cytometry cohort, patients were defined as “positive” for bone marrow micrometastatic disease if their CD99+/CD45− values were above the upper limit in 22 control patients. In the PCR cohort, RT-PCR on blood or bone marrow samples classified the patients as “positive” or “negative” for EWSR1/FLI1 translocations. The association between micrometastatic disease burden with clinical features and outcome was assessed. Coexpression of insulin-like growth factor-1 receptor (IGF-1R) on detected tumor cells was performed in a subset of flow cytometry samples.Results: The median total bone marrow CD99+CD45− percent was 0.0012% (range 0%–1.10%) in the flow cytometry cohort, with 14 of 109 (12.8%) of Ewing sarcoma patients defined as “positive.” In the PCR cohort, 19.6% (44/225) patients were “positive” for any EWSR1/FLI1 translocation in blood or bone marrow. There were no differences in baseline clinical features or event-free or overall survival between patients classified as “positive” versus “negative” by either method. CD99+CD45− cells had significantly higher IGF-1R expression compared with CD45+ hematopoietic cells (mean geometric mean fluorescence intensity 982.7 vs. 190.9; P < 0.001).Conclusions: The detection of micrometastatic disease at initial diagnosis by flow cytometry or RT-PCR is not associated with outcome in newly diagnosed patients with Ewing sarcoma. Flow cytometry provides a tool to characterize occult micrometastatic tumor cells for proteins of interest. Clin Cancer Res; 22(14); 3643–50. ©2016 AACR.

We sought to analyze biologic, clinical, and prognostic differences according to pattern of failure at the time of first relapse in neuroblastoma.Children21 years diagnosed with neuroblastoma between 1989 and 2017 with known site of first relapse (isolated local vs. distant only vs. combined local and distant sites) were identified from the International Neuroblastoma Risk Group (INRG) database. Data were compared between sites of relapse according to clinical features, biologic features, initial treatment, time to first relapse, and overall survival (OS) from time of first relapse.Pattern of first relapse among 1833 children was 19% isolated local; 65% distant only; and 16% combined sites. All evaluated clinical and biologic variables with exception of tumor diagnosis differed statistically by relapse pattern, with patients with isolated local failure having more favorable prognostic features. Patients with stage 3 disease were more likely to have isolated local failure compared to all other stages (49% vs. 16%; p .001). OS significantly differed by relapse pattern (5-year OS ± SE): isolated local: 64% ± 3%; distant only: 23% ± 2%; and combined: 26% ± 4% (p .001). After controlling for age, stage, and MYCN status, patients with isolated local failure (adjusted hazard ratio [HR] = 0.46; 95% confidence interval [CI]: 0.33-0.62; p .001) and distant-only failure (adjusted HR = 0.57; 95% CI: 0.45-0.71; p .001) remained at decreased risk for death as compared to patients with combined failure.Patients with distant-only and combined failures have a higher proportion of unfavorable clinical and biological features, and a lower survival than those with isolated local relapse.

Most circulating tumor DNA (ctDNA) assays are designed to detect recurrent mutations. Pediatric sarcomas share few recurrent mutations but rather are characterized by translocations and copy-number changes. We applied Cancer Personalized Profiling by deep Sequencing (CAPP-Seq) for detection of translocations found in the most common pediatric sarcomas. We also applied ichorCNA to the combined off-target reads from our hybrid capture to simultaneously detect copy-number alterations (CNA). We analyzed 64 prospectively collected plasma samples from 17 patients with pediatric sarcoma. Translocations were detected in the pretreatment plasma of 13 patients and were confirmed by tumor sequencing in 12 patients. Two of these patients had evidence of complex chromosomal rearrangements in their ctDNA. We also detected copy-number changes in the pretreatment plasma of 7 patients. We found that ctDNA levels correlated with metastatic status and clinical response. Furthermore, we detected rising ctDNA levels before relapse was clinically apparent, demonstrating the high sensitivity of our assay. This assay can be utilized for simultaneous detection of translocations and CNAs in the plasma of patients with pediatric sarcoma. While we describe our experience in pediatric sarcomas, this approach can be applied to other tumors that are driven by structural variants.

PURPOSE 131I-metaiodobenzylguanidine (MIBG) is an active radiotherapeutic for neuroblastoma. The primary aim of this trial was to identify which of three MIBG regimens was likely associated with the highest true response rate. PATIENTS AND METHODS Patients 1-30 years were eligible if they had relapsed or refractory neuroblastoma, at least one MIBG-avid site, and adequate autologous stem cells. Patients received MIBG 18 mCi/kg on day 1 and autologous stem cell on day 15. Patients randomly assigned to arm A received only MIBG; patients randomly assigned to arm B received intravenous vincristine on day 0 and irinotecan daily on days 0-4; patients randomly assigned to arm C received vorinostat (180 mg/m2/dose) orally once daily on days 1 to 12. The primary end point was response after one course by New Approaches to Neuroblastoma Therapy criteria. The trial was designed with 105 patients to ensure an 80% chance that the arm with highest response rate was selected. RESULTS One hundred fourteen patients were enrolled, with three ineligible and six unevaluable, leaving 105 eligible and evaluable patients (36 in arm A, 35 in arm B, and 34 in arm C; 55 boys; and median age 6.5 years). After one course, the response rates (partial response or better) on arms A, B, and C were 14% (95% CI, 5 to 30), 14% (5 to 31), and 32% (18 to 51). An additional five, five, and four patients met New Approaches to Neuroblastoma Therapy Minor Response criteria on arms A, B, and C, respectively. On arms A, B, and C, rates of any grade 3+ nonhematologic toxicity after first course were 19%, 49%, and 35%. CONCLUSION Vorinostat and MIBG is likely the arm with the highest true response rate, with manageable toxicity. Vincristine and irinotecan do not appear to improve the response rate to MIBG and are associated with increased toxicity.

Purpose Radiation dose calculated on tumors for radiopharmaceutical therapy varies significantly from tumor to tumor and from patient to patient. Accurate estimation of radiation dose requires multiple time point measurements using radionuclide imaging modalities such as SPECT or PET. In this report, we show our technical development of reducing the number of scans needed for reasonable estimation of tumor and normal organ dose in our pretherapy imaging and dosimetry platform of 124 I-metaiodobenzylguanidine (MIBG) positron emission tomography/computed tomography (PET/CT) for 131 I-MIBG therapy of neuroblastoma. Methods We analyzed the simplest kinetic data, areas of two-time point data for five patients with neuroblastoma who underwent 3 or 4 times of 124 I-MIBG PET/CT scan prior to 131 I-MIBG therapy. The data for which we derived areas were percent of injected activity (%IA) and standardized uptake value of tumors. These areas were correlated with time-integrated activity coefficients (TIACs) from full data (3 or 4 time points). TIACs are direct correlates with radiation dose as long as the volume and the radionuclide are known. Results The areas of %IAs between data obtained from all the two-time points with time points 1 and 2 (day 0 and day 1), time points 2 and 3 (day 1 and day 2), and time points 1 and 3 (day 0 and day 2) showed reasonable correlation (Pearson's correlation coefficient |r| > 0.5) with not only tumor and organ TIACs but also tumor and organ absorbed doses. The tumor and organ doses calculated using %IA areas of time point 1 and time point 2 were our best fits at about 20% individual percent difference compared to doses calculated using 3 or 4 time points. Conclusions We could achieve reasonable accuracy of estimating tumor doses for subsequent radiopharmaceutical therapy using only the two-time point imaging sessions. Images obtained from these time points (within the 48-h after administration of radiopharmaceutical) were also viewed as useful for diagnostic reading. Although our analysis was specific to 124 I-MIBG PET/CT pretherapy imaging data for 131 I-MIBG therapy of neuroblastoma and the number of imaging datasets was not large, this feasible methodology would generally be applicable to other imaging and therapeutic radionuclides with an appropriate data analysis similar to our analysis to other imaging and therapeutic radiopharmaceuticals.

The metaiodobenzylguanidine (MIBG) scan is one of the most sensitive noninvasive lesion detection modalities for neuroblastoma. Unlike (123)I-MIBG, (124)I-MIBG allows high-resolution PET. We evaluated (124)I-MIBG PET/CT for its diagnostic performance as directly compared with paired (123)I-MIBG scans. Methods: Before (131)I-MIBG therapy, standard (123)I-MIBG imaging (5.2 MBq/kg) was performed on 7 patients, including whole-body (anterior–posterior) planar imaging, focused-field-of-view SPECT/CT, and whole-body (124)I-MIBG PET/CT (1.05 MBq/kg). After therapy, 2 of 7 patients also completed (124)I-MIBG PET/CT as well as paired (123)I-MIBG planar imaging and SPECT/CT. One patient underwent (124)I-MIBG PET/CT only after therapy. We evaluated all 8 patients who showed at least 1 (123)I-MIBG–positive lesion with a total of 10 scans. In 8 pairs, (123)I-MIBG and (124)I-MIBG were performed within 1 mo of each other. The locations of identified lesions, the number of total lesions, and the curie scores were recorded for the (123)I-MIBG and (124)I-MIBG scans. Finally, for 5 patients who completed at least 3 PET/CT scans after administration of (124)I-MIBG, we estimated the effective dose of (124)I-MIBG. Results: (123)I-MIBG whole-body planar scans, focused-field-of-view SPECT/CT scans, and whole-body (124)I-MIBG PET scans found 25, 32, and 87 total lesions, respectively. There was a statistically significant difference in lesion detection for (124)I-MIBG PET/CT versus (123)I-MIBG planar imaging (P < 0.0001) and (123)I-MIBG SPECT/CT (P < 0.0001). The curie scores were also higher for (124)I-MIBG PET/CT than for (123)I-MIBG planar imaging and SPECT/CT in 6 of 10 patients. (124)I-MIBG PET/CT demonstrated better detection of lesions throughout the body, including the chest, spine, head and neck, and extremities. The effective dose estimated for patient-specific (124)I-MIBG was approximately 10 times that of (123)I-MIBG; however, given that we administered a very low activity of (124)I-MIBG (1.05 MBq/kg), the effective dose was only approximately twice that of (123)I-MIBG despite the large difference in half-lives (100 vs. 13.2 h). Conclusion: The first-in-humans use of low-dose (124)I-MIBG PET for monitoring disease burden demonstrated tumor detection capability superior to that of (123)I-MIBG planar imaging and SPECT/CT.

Background Clinical, molecular, and histopathologic features guide treatment for neuroblastoma, but obtaining tumor tissue may cause complications and is subject to sampling error due to tumor heterogeneity. We hypothesized that image‐defined risk factors (IDRFs) would reflect molecular features, histopathology, and clinical outcomes in neuroblastoma. Methods We performed a retrospective cohort study of 76 patients with neuroblastoma or ganglioneuroblastoma. Diagnostic CT scans were reviewed for 20 IDRFs, which were consolidated into five IDRF groups (involvement of multiple body compartments, vascular encasement, tumor infiltration of adjacent organs/structures, airway compression, or intraspinal extension). IDRF groups were analyzed for association with clinical, molecular, and histopathologic features of neuroblastoma. Results Patients with more IDRF groups had a higher risk of surgical complications (OR = 3.1, p = 0.001). Tumor vascular encasement was associated with increased risk of surgical complications (OR = 5.40, p = 0.009) and increased risk of undifferentiated/poorly differentiated histologic grade (OR = 11.11, p = 0.013). Tumor infiltration of adjacent organs and structures was associated with decreased survival (HR = 8.90, p = 0.007), MYCN amplification (OR = 9.91, p = 0.001), high MKI (OR = 6.20, p = 0.003), and increased risk of International Neuroblastoma Staging System stage 4 disease (OR = 8.96, p, This is an original research article that explored the association between neuroblastoma image‐defined risk factors (IDRFs) present at diagnosis and various histopathologic, surgical, and survival outcomes. To our knowledge, this is the first report showing that neuroblastoma IDRFs were associated with histopathology in addition to MYCN amplification. It is also the first time, to our knowledge, that specific imaging biomarkers in neuroblastoma, such as tumor vascular encasement and tumor infiltration into adjacent organs and structures, were associated with histopathology and decreased survival.

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.

Improvements in outcome have been seen in children and adolescents with cancer. Nevertheless, challenges remain in trying to improve the outcomes for all children diagnosed with cancer, particularly in patients with metastatic disease or with cancers that are resistant or recur after standard treatment. Precision medicine trials using individualized tumor molecular profiling for selection of targeted therapies are ongoing in adult malignancies. Similar approaches are being applied to children and adolescents with cancer. This article describes how precision medicine is being applied to pediatric oncology and the unique challenges being faced with these efforts.

TPS11575 Background: Osteosarcoma is the most common primary bone tumor, occurring in children, adolescents, and young adults. In contrast to advances in treatment for most childhood cancers, there have been no significant improvements in osteosarcoma outcomes in the past 40 years. Forty percent of osteosarcoma patients will, at some point, have advanced disease which has a very poor outcome with a 5-year overall survival of approximately 20%. Genomic alterations and signatures associated with sensitivity to treatment with DNA damage response (DDR) inhibitors are observed frequently in osteosarcoma. Many osteosarcomas have a unique mutational signature (signature 3) similar to that seen in BRCA1 deficient cancer and response to PARP inhibitors has been seen in osteosarcoma cell lines. Additionally, ATRX, a protein involved in the alternative lengthening of telomeres (ALT), is often inactivated in osteosarcoma. Defects in the ALT pathway may sensitize tumor cells to ATR inhibitors and osteosarcoma cell lines have been shown to be sensitive to ATR inhibition. In vitro susceptibility of osteosarcoma cell lines to ATR and PARP inhibitors, the presence of mutations in genes involved in DDR and the presence of signature 3 in a subset of osteosarcomas serves as the basis for the development of this trial. Methods: This is an ongoing open label, multicenter, phase II clinical trial to evaluate the clinical activity of PARP inhibitor, olaparib, in combination with ATR inhibitor, ceralasertib, in 2 cohorts of patients aged 12-40 with recurrent osteosarcoma (NCT04417062). Patients with unresectable disease are enrolled into Cohort 1. Patients with resectable disease limited to the lung are enrolled into Cohort 2. Patients in both cohorts receive olaparib 300mg orally twice a day on days 1-28 and ceralasertib 160 mg orally once a day on days 1-7 of a 28-day cycle (adult maximum tolerated dose for the combination). For patients in Cohort 2, study treatment also includes surgical resection of lung metastases at protocol-specified timepoints. Patients can remain on treatment for up to 2 years if they have not progressed. For Cohort 1, the primary objective is to determine whether the combination treatment improves the 4-month event-free rate as compared to a historical benchmark from Children’s Oncology Group (COG) trials using a Simon’s two-stage design. In the first stage, ≥3 of 19 patients must be event-free at 4 months to proceed to stage 2. Enrollment into Cohort 2 continues as long as Cohort 1 enrollment is ongoing. For Cohort 2, the primary endpoint is the submission of paired pre- and post-treatment tumor samples for correlative studies. Secondary endpoints include objective response rate, event-free survival, and overall survival. Integrated correlative studies will assess tumor tissue for biomarkers of treatment response and measure circulating tumor DNA longitudinally. Enrollment began November 24, 2020 and is ongoing. Clinical trial information: NCT04417062.

// Kieuhoa T. Vo 1 , Erin E. Karski 1 , Nicole M. Nasholm 1 , Shelly Allen 1 , Fabienne Hollinger 1 , W. Clay Gustafson 1 , Janel R. Long-Boyle 2 , Stephen Shiboski 3 , Katherine K. Matthay 1 and Steven G. DuBois 1 1 Department of Pediatrics, UCSF Benioff Children’s Hospital, University of California, San Francisco School of Medicine, San Francisco, CA, USA 2 Department of Clinical Pharmacy, UCSF Benioff Children’s Hospital, University of California, San Francisco School of Medicine, San Francisco, CA, USA 3 Department of Epidemiology and Biostatistics, UCSF Benioff Children’s Hospital, University of California, San Francisco School of Medicine, San Francisco, CA, USA Correspondence to: Kieuhoa T. Vo, email: // Keywords : phase 1, mTOR, sirolimus, topotecan, cyclophosphamide Received : August 23, 2016 Accepted : October 13, 2016 Published : October 25, 2016 Abstract Purpose: To determine the maximum tolerated dose (MTD), toxicities, and pharmacodynamics effects of sirolimus combined with oral metronomic topotecan and cyclophosphamide in a pediatric population. Materials and Methods: Patients who were 1 to 30 years of age with relapsed/refractory solid tumors (including CNS) were eligible. Patients received daily oral sirolimus and cyclophosphamide (25-50 mg/m 2 /dose) on days 1-21 and oral topotecan (0.8 mg/m 2 /dose) on days 1-14 in 28-day cycles. Sirolimus steady-state plasma trough concentrations of 3-7.9 ng/mL and 8-12.0 ng/mL were evaluated, with dose escalation based on a 3+3 phase 1 design. Biomarkers of angiogenesis were also evaluated. Results: Twenty-one patients were treated (median age 18 years; range 9-30). Dose-limiting toxicities included myelosuppression, ALT elevation, stomatitis, and hypertriglyceridemia. The MTD was sirolimus with trough goal of 8-12.0 ng/mL; cyclophosphamide 25 mg/m 2 /dose; and topotecan 0.8 mg/m 2 /dose. No objective responses were observed. Four patients had prolonged stable disease > 4 cycles (range 4-12). Correlative biomarker analyses demonstrated reductions in thrombospondin-1 ( p =0.043) and soluble vascular endothelial growth factor receptor-2 plasma concentrations at 21 days compared to baseline. Conclusions: The combination of oral sirolimus, topotecan, and cyclophosphamide was well tolerated and biomarker studies demonstrated modulation of angiogenic pathways with this regimen.

High-risk neuroblastoma has a poor prognosis, and research studies have shown that increasing the intensity of therapy improves outcomes. Autologous hematopoietic cell transplant (aHCT) as consolidation therapy confers a significant survival advantage but is accompanied by significant morbidity. Transplant-associated thrombotic microangiopathy (TA-TMA) is a life-threatening complication caused by endothelial injury that often leads to hemolytic anemia, microthrombotic platelet consumption, and renal injury. Here we investigated the incidence, potential risk factors, and sequelae of TA-TMA in patients with high-risk neuroblastoma. We conducted a retrospective chart review of all patients (n = 141) with neuroblastoma in our institutions who underwent aHCT from 2000 to 2017. Ten patients (7%) developed TA-TMA. The patients in the TA-TMA group were similar to the rest of the subjects in demographics, disease burden, prior therapies, renal function, and timing of transplant. The type of conditioning regimen was the only statistically significant pretransplant variable (P < .001). Six of 15 patients (40%) intended to receive tandem transplants (cyclophosphamide/thiotepa and then carboplatin/etoposide/melphalan (CEM)), 4 of 68 patients (6%) who received conditioning with single CEM, and none of the 56 patients who received busulfan/melphalan were diagnosed with TA-TMA. Patients with TA-TMA were more likely to require intensive care unit transfer, have a longer length of stay in the hospital, and experience a delay or change in their subsequent therapy. In our cohort overall, patients with a delay in therapy after transplant appeared to have a worse overall survival, although the difference was not statistically significant. Because of this high incidence and significant morbidity, we have implemented standardized screening for TA-TMA during and after transplant. We anticipate that screening will lead to earlier intervention and decreased severity of disease.

Purpose: Flow cytometry and RT-PCR can detect occult Ewing sarcoma cells in the blood and bone marrow. These techniques were used to evaluate the prognostic significance of micrometastatic disease in Ewing sarcoma. Experimental Design: Newly diagnosed patients with Ewing sarcoma were enrolled on two prospective multicenter studies. In the flow cytometry cohort, patients were defined as “positive” for bone marrow micrometastatic disease if their CD99+/CD45− values were above the upper limit in 22 control patients. In the PCR cohort, RT-PCR on blood or bone marrow samples classified the patients as “positive” or “negative” for EWSR1/FLI1 translocations. The association between micrometastatic disease burden with clinical features and outcome was assessed. Coexpression of insulin-like growth factor-1 receptor (IGF-1R) on detected tumor cells was performed in a subset of flow cytometry samples. Results: The median total bone marrow CD99+CD45− percent was 0.0012% (range 0%–1.10%) in the flow cytometry cohort, with 14 of 109 (12.8%) of Ewing sarcoma patients defined as “positive.” In the PCR cohort, 19.6% (44/225) patients were “positive” for any EWSR1/FLI1 translocation in blood or bone marrow. There were no differences in baseline clinical features or event-free or overall survival between patients classified as “positive” versus “negative” by either method. CD99+CD45− cells had significantly higher IGF-1R expression compared with CD45+ hematopoietic cells (mean geometric mean fluorescence intensity 982.7 vs. 190.9; P < 0.001). Conclusions: The detection of micrometastatic disease at initial diagnosis by flow cytometry or RT-PCR is not associated with outcome in newly diagnosed patients with Ewing sarcoma. Flow cytometry provides a tool to characterize occult micrometastatic tumor cells for proteins of interest. Clin Cancer Res; 22(14); 3643–50. ©2016 AACR.

Purpose Long-term survivors of Ewing sarcoma (EWS) are at considerable risk for future complications, including late relapse and death. Data on prognostic factors for late death in those who have survived beyond 5 years are lacking. Methods We conducted a retrospective cohort study using the Surveillance, Epidemiology, and End Results database. We obtained clinical features and outcome data on 1,351 patients with EWS who had survived 60 months or more. From these data, we performed univariate and multivariable analyses of overall survival (OS) using log-rank tests and Cox proportional hazard models. Results Of 1,351 patients in the cohort, there were 209 deaths, 144 (69%) of which were reported to be due to EWS. The OS for 5-year survivors at 10 years was 87.5% (95% confidence interval 85.4–89.3%). Univariate adverse prognostic factors for late death in 5-year survivors included age ≥ 18 years at initial diagnosis, male sex, and axial/pelvic primary site. Initial stage was not prognostic. Independent adverse prognostic factors for late death included black race (hazard ratio [HR] 2.16, P = 0.01), age ≥ 18 years at diagnosis (HR 2.02, P < 0.001), male sex (HR 1.43, P = 0.01), and axial/pelvic primary site (HR 1.43, P = 0.02). Conclusions The majority of late deaths in 5-year survivors are due to EWS. Black race, age ≥18 at diagnosis, male sex, and axial/pelvic primary site (but not stage at diagnosis) are independently associated with increased risk of late death.

BACKGROUND MYCN gene amplification (MNA) is a hallmark of aggressive neuroblastoma. This study was performed to determine univariate and multivariate predictors of tumor MNA. METHODS Data from the International Neuroblastoma Risk Group were analyzed for a subset of 7102 patients with known MYCN status. Chi-square testing and logistic regression were used to identify univariate and multivariate predictors of MYCN status. Recursive partitioning was used to identify groups of patients with maximal differences in rates of MNA. RESULTS All clinical features (age ≥ 18 months, high ferritin levels, high lactate dehydrogenase [LDH] levels, International Neuroblastoma Staging System stage 4, and adrenal sites) and pathological/biological features (DNA index ≤ 1, high mitosis-karyorrhexis index [MKI], undifferentiated/poorly differentiated grade, unfavorable histology according to the International Neuroblastoma Pathology Classification, and segmental chromosomal aberrations [SCAs]) were significantly associated with MNA. LDH (odds ratio [OR], 8.4; P

10526 Background: Pro-angiogenic factors may represent therapeutic targets in sarcoma. Preclinical studies have demonstrated a potential additive or synergistic interaction between anti-angiogenic agents and chemotherapy. The purpose of this study was to determine the maximum tolerated dose (MTD), toxicities, pharmacokinetic (PK) and pharmacodynamics (PD) effects of PAZIT in patients with advanced sarcoma. Methods: Patients 6-30 years of age with relapsed/refractory sarcomas were eligible. In the initial dose escalation plan (A), patients received pazopanib PO (225-450 mg/m2/dose) on Days 1-21 of 21-day cycles. Pazopanib was combined with fixed doses of irinotecan (IV 50 or PO 90 mg/m2/dose) and temozolomide PO 100 mg/m2/dose on Days 1-5. Due to DLTs, an amendment was made to the dose escalation plan (B) and patients received fixed doses of pazopanib PO (225 mg/m2/dose) on Days 1-21 of 21-day cycles and reduced irinotecan doses (IV 25-37.5 or PO 45-67.5 mg/m2/dose) and temozolomide PO 100 mg/m2/dose on Days 1-5. Oral cephalosporin diarrhea prophylaxis was required. Dose escalation followed a 3+3 design. Correlative studies included PK (pazopanib, irinotecan) and PD (angiogenic factors, ctDNA) effects. Results: Sixteen patients were treated (median age 16 years, range 7-21). The dose levels in the table were evaluated. First cycle DLTs occurred at all dose levels (Table) and included diarrhea, pancreatitis, colitis, neutropenia, hypertension, deep vein thrombosis, and ALT increase. Due to excessive toxicity, an MTD could not be established. One patient with osteosarcoma had a partial response. Four patients had prolonged stable disease > 4 cycles, including 2 patients with Ewing sarcoma (5 and 6 cycles), rhabdomyosarcoma (9 cycles), and desmoplastic small round cell tumor (6 cycles). Mean±SD plasma exposures to pazopanib, irinotecan, and SN-38 in patients treated on dose level 1B (n = 4) on Day 4 were 601±83, 1.4±0.2 and 0.1±0.04 ug/mL*hr, respectively. Analyses of correlative studies are ongoing. Conclusions: Combination PAZIT therapy is not tolerable as evaluated at these doses/schedules. This study provides important toxicity data to inform future clinical trials using combination anti-angiogenic strategies in sarcoma. Clinical trial information: NCT03139331. [Table: see text]

BACKGROUND: TP53 mutations are rare across pediatric cancers. Recent work using CRISPR-Cas9 screens has demonstrated that MDM2 and MDMX are strong dependencies in a range of TP53-wildtype pediatric malignancies. Increased expression of MDM2 and MDMX is a common mechanism for suppressing p53 in pediatric malignancies and can occur by copy number gain or amplification, as has been reported in retinoblastoma and hepatoblastoma. In pediatric high-grade gliomas, activating PPM1D mutations drive p53 suppression, likely through MDM2 stabilization. ALRN-6924 is a novel, first-in-class, cell-permeating stapled peptide that disrupts the inhibitory interactions between MDM2/MDMX(MDM4) and p53. ALRN-6924 has been evaluated in two adult Phase I trials, with good tolerability and evidence of clinical activity across a range of cancer subtypes. Given the oncogenic roles of MDM2 and MDMX in pediatric malignancies, we developed a Phase I clinical trial designed to evaluate the tolerability, pharmacokinetics, and pharmacodynamic and antitumor activity of ALRN-6924. METHODS: This is a Phase I, open-label, investigator-initiated multicenter study of ALRN-6924 in children 1-21 years of age with relapsed/refractory cancer (NCT03654716). The primary objectives are to determine the recommended phase 2 dose, and to describe toxicities and pharmacokinetic parameters of ALRN-6924 in this population. The monotherapy arm consists of two cohorts: Cohort A for patients with TP53-wildtype solid tumors and lymphomas; and Cohort B for patients with retinoblastoma, or TP53-wildtype tumors that meet any of the following criteria: hepatoblastoma, malignant rhabdoid tumor, MDM2 or MDMX amplification, TET2 loss, or PPM1D activating mutations. Patients with CNS primary tumors are only eligible for Cohort B. In Cohorts A and B, patients receive ALRN-6924 intravenously on Days 1, 4, 8 and 11 of a 21-day cycle starting at a dose of 2.2 mg/kg. An expansion cohort for patients eligible for Cohort B will open following completion of monotherapy dose escalation. Patients with relapsed/refractory leukemias enroll to Cohort C and receive ALRN-6924 in combination with low-dose cytarabine on days 1, 8 and 15 of a 28-day cycle starting at a dose of 2.7 mg/kg. Pharmacokinetic sampling and pharmacodynamic testing (serum MIC-1 modulation) is required for all patients. Correlative biology studies will include evaluation of circulating tumor DNA for TP53 mutations in patients with solid tumors and serial assessment of leukemic blasts in patients with relapsed leukemia. Enrollment began in October 2018. Up to 69 patients will be enrolled. Citation Format: David S. Shulman, Kieuhoa T. Vo, Elizabeth Fox, Jodi A. Muscal, Loren D. Walensky, Yana Pikman, Kimberly Stegmaier, Alanna Church, Brian D. Crompton, Andrew E. Place, Susan N. Chi, Allison F. O'Neill, Junne Kamihara, Suzanne Ezrre, Cecilia Carlowicz, Dawn Pinchasik, Hasan Al-Sayegh, Clement Ma, Wendy B. London, Steven G. DuBois. A Phase I multicenter trial of the dual MDM2/MDMX inhibitor ALRN-6924 in children and young adults with relapsed/refractory pediatric cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT112.

Several reports of second malignant neoplasm (SMN) in patients with relapsed neuroblastoma after treatment with (131)I-MIBG suggest the possibility of increased risk. Incidence of and risk factors for SMN after (131)I-MIBG have not been defined. This is a multi-institutional retrospective review of patients with neuroblastoma treated with (131)I-MIBG therapy. A competing risk approach was used to calculate the cumulative incidence of SMN from time of first exposure to (131)I-MIBG. A competing riskregression was used to identify potential risk factors for SMN. The analytical cohort included 644 patients treated with (131)I-MIBG. The cumulative incidence of SMN was 7.6% (95% confidence interval [CI], 4.4-13.0%) and 14.3% (95% CI, 8.3-23.9%) at 5 and 10 years from first (131)I-MIBG, respectively. No increase in SMN risk was found with increased number of (131)I-MIBG treatments or higher cumulative activity per kilogram of (131)I-MIBG received (p=0.72 and p=0.84, respectively). Thirteen of the 19 reported SMN were haematologic. In a multivariate analysis controlling for variables with p&nbsp

Long-term survivors of Ewing sarcoma (EWS) are at considerable risk for future complications, including late relapse and death. Data on prognostic factors for late death in those who have survived beyond 5 years are lacking.We conducted a retrospective cohort study using the Surveillance, Epidemiology, and End Results database. We obtained clinical features and outcome data on 1,351 patients with EWS who had survived 60 months or more. From these data, we performed univariate and multivariable analyses of overall survival (OS) using log-rank tests and Cox proportional hazard models.Of 1,351 patients in the cohort, there were 209 deaths, 144 (69%) of which were reported to be due to EWS. The OS for 5-year survivors at 10 years was 87.5% (95% confidence interval 85.4-89.3%). Univariate adverse prognostic factors for late death in 5-year survivors included age ≥ 18 years at initial diagnosis, male sex, and axial/pelvic primary site. Initial stage was not prognostic. Independent adverse prognostic factors for late death included black race (hazard ratio [HR] 2.16, P = 0.01), age ≥ 18 years at diagnosis (HR 2.02, P0.001), male sex (HR 1.43, P = 0.01), and axial/pelvic primary site (HR 1.43, P = 0.02).The majority of late deaths in 5-year survivors are due to EWS. Black race, age ≥18 at diagnosis, male sex, and axial/pelvic primary site (but not stage at diagnosis) are independently associated with increased risk of late death.

TPS10576Background: Sarcomas express pro-angiogenic factors that may represent therapeutic targets. Pazopanib, an oral multi-kinase inhibitor of VEGFR-(1-3), c-kit, and PDGFR, is FDA-approved for t...

TPS10576 Background: CUDC-907 is an oral first-in-class small molecule inhibitor of histone deacetylases (HDACs) and phosphatidylinositol-3-kinases (PI3Ks), two enzyme classes commonly implicated in pediatric malignancies. Preclinical data demonstrate that inhibition of these enzymes decreases tumor growth across a range of histologies. Data from preclinical and clinical studies suggest that down-regulation of Myc or Mycn signaling may be important in the antineoplastic effects of CUDC-907. Myc or Mycn signaling appears to drive a number of pediatric cancers, heralds a poor prognosis in many of these diseases and has proven difficult to target. CUDC-907 has completed adult phase I testing in patients with hematologic malignancies. The drug was tolerable using a 5 days on/2 days off (5/2) dosing strategy, with a recommended phase II dose of 60 mg. Diarrhea, fatigue, nausea and thrombocytopenia were the most commonly reported side effects. Partial and complete responses were observed in patients with Myc-altered diffuse large B cell lymphoma. Methods: This study is a phase I, open-label, multicenter trial of CUDC-907 in patients 1-21 years of age with relapsed/refractory solid tumors, brain tumors and lymphomas (NCT02909777). The primary objectives are to determine the recommended phase II dose, describe toxicities, and describe pharmacokinetic parameters of CUDC-907 in this population. Other objectives include evaluation of disease response and exploration of the pharmacodynamic effects of CUDC-907. Patients receive CUDC-907 orally on a 5/2 schedule in 28-day cycles, with a pediatric mini-tab formulation available for younger children. Part A consists of a standard 3+3 design evaluating up to three dose levels. Following dose escalation, Part B consists of two expansion cohorts for patients with Mycn/Myc-driven neuroblastoma or mature B-cell lymphoma. Up to 44 patients may be enrolled across Parts A and B. Detailed pharmacokinetic testing is required in the first two cycles. Optional pharmacodynamic testing will quantify histone acetylation, Myc protein, and phospho-S6 in serial blood samples. Enrollment began in October 2016 and is ongoing. Clinical trial information: NCT02909777.

Purpose Neuroblastoma (NB) is a heterogeneous tumor arising from sympathetic tissues. The impact of primary tumor site in influencing the heterogeneity of NB remains unclear. Patients and Methods Children younger than age 21 years diagnosed with NB or ganglioneuroblastoma between 1990 and 2002 and with known primary site were identified from the International Neuroblastoma Risk Group database. Data were compared between sites with respect to clinical and biologic features, as well as event-free survival (EFS) and overall survival (OS). Results Among 8,369 children, 47% had adrenal tumors. All evaluated clinical and biologic variables differed statistically between primary sites. The features that were > 10% discrepant between sites were stage 4 disease, MYCN amplification, elevated ferritin, elevated lactate dehydrogenase, and segmental chromosomal aberrations, all of which were more frequent in adrenal versus nonadrenal tumors (P < .001). Adrenal tumors were more likely than nonadrenal tumors (adjusted odds ratio, 2.09; 95% CI, 1.67 to 2.63; P < .001) and thoracic tumors were less likely than nonthoracic tumors (adjusted odds ratio, 0.20; 95% CI, 0.11 to 0.39; P < .001) to have MYCN amplification after controlling for age, stage, and histologic grade. EFS and OS differed significantly according to the primary site (P < .001 for both comparisons). After controlling for age, MYCN status, and stage, patients with adrenal tumors had higher risk for events (hazard ratio, 1.13 compared with nonadrenal tumors; 95% CI, 1.03 to 1.23; P = .008), and patients with thoracic tumors had lower risk for events (HR, 0.79 compared with nonthoracic; 95% CI, 0.67 to 0.92; P = .003). Conclusion Clinical and biologic features show important differences by NB primary site, with adrenal and thoracic sites associated with inferior and superior survival, respectively. Future studies will need to investigate the biologic origin of these differences.

Heavy menstrual bleeding (HMB) is a frequent complaint in adolescence. Although HMB is often caused by immaturity of the hypothalamic-pituitary-ovarian axis, bleeding disorders are another common yet often unidentified cause. The aim of this study was to examine the bleeding patterns and prevalence of inherited bleeding disorders among females referred for HMB to a multidisciplinary adolescent haematology clinic. We retrospectively reviewed the first 105 patients (ages 8-18 years) referred to this specialty clinic from February 2009 to December 2011. Using menstrual bleeding questionnaires and medical records, data were extracted regarding demographics, bleeding patterns, frequency and types of bleeding disorders identified, and prescribed interventions. Sixty-two per cent of patients were diagnosed with a bleeding disorder, including platelet storage pool deficiency (36%), von Willebrand's disease (9%), other platelet function defect (8%), Ehlers-Danlos syndrome (7%) and combined bleeding disorders (2%). Comparison of the bleeding profiles for females with and without a bleeding disorder revealed only three factors that were significantly different, including the reported regularity of patients' periods (P = 0.02), description of period flow (P = 0.04) and number of days of each period that the bleeding was described as 'heavy' (P = 0.007). Bleeding disorders are prevalent in adolescent females presenting to a specialty clinic. Specifically, a relatively high proportion of adolescents were diagnosed with platelet storage pool deficiency. In our small population, menstrual bleeding profiles, as examined by a standardized questionnaire, could not identify females with an underlying bleeding disorder, demonstrating the important role of haemostasis testing in the evaluation of adolescents with HMB.

Sarcomas are a heterogeneous group of mesenchymal malignancies. In recent years, studies have demonstrated that inhibition of angiogenic pathways or disruption of established vasculature can attenuate the growth of sarcomas. However, when used as monotherapy in the clinical setting, these targeted antiangiogenic agents have only provided modest survival benefits in some sarcoma subtypes, and have not been efficacious in others. Preclinical and early clinical data suggest that the addition of conventional chemotherapy to antiangiogenic agents may lead to more effective therapies for patients with these tumors. In the current review, the authors summarize the available evidence and possible mechanisms supporting this approach.