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Unrelated donor (URD) hematopoietic stem cell transplant (HSCT) is associated with an increased risk of severe graft-versus-host disease (GVHD). TCRαβ/CD19 depletion may reduce this risk, whereas maintaining graft-versus-leukemia. Outcome data with TCRαβ/CD19 depletion generally describe haploidentical donors, with relatively few URDs. We hypothesized that TCRαβ/CD19-depletion would attenuate the risks of GVHD and relapse for URD HSCT. Sixty pediatric and young adult (YA) patients with hematologic malignancies who lacked a matched-related donor were enrolled at 2 large pediatric transplantation centers between October 2014 and September 2019. All patients with acute leukemia had minimal residual disease testing, and DP typing was available for 77%. All patients received myeloablative total body irradiation– or busulfan-based conditioning with no posttransplant immune suppression. Engraftment occurred in 98%. Four-year overall survival was 69% (95% confidence interval [CI], 52%-81%), and leukemia-free survival was 64% (95% CI, 48%-76%), with no difference between lymphoid and myeloid malignancies (P = .6297 and P = .5441, respectively). One patient (1.7%) experienced primary graft failure. Relapse occurred in 11 patients (3-year cumulative incidence, 21%; 95% CI, 11-34), and 8 patients (cumulative incidence, 15%; 95% CI, 6.7-26) experienced nonrelapse mortality. Grade III to IV acute GVHD was seen in 8 patients (13%), and 14 patients (26%) developed chronic GVHD, of which 6 (11%) had extensive disease. Nonpermissive DP mismatch was associated with higher likelihood of acute GVHD (odds ratio, 16.50; 95% CI, 1.67-163.42; P = .0166) but not with the development of chronic GVHD. URD TCRαβ/CD19-depleted peripheral HSCT is a safe and effective approach to transplantation for children/YAs with leukemia. This trial was registered at www.clinicaltrials.gov as #NCT02323867.

Gemtuzumab ozogamicin (GO) is an anti-CD33 antibody-tumor antibiotic conjugate with proven efficacy in pediatric and adult patients with CD33+ acute myeloid leukemia. Adverse effects commonly associated with GO include hyperbilirubinemia, elevated transaminases, and sinusoidal obstruction syndrome. Cardiotoxicity has not been a commonly described adverse event. We describe two pediatric patients with relapsed/refractory acute myeloid leukemia who received fractionated GO monotherapy and subsequently developed severe acute left ventricular dysfunction. Both patients achieved remission, recovered cardiac function with medical therapy, and tolerated subsequent stem cell transplantation.

An adequate absolute lymphocyte count (ALC) is an essential first step in autologous chimeric antigen receptor (CAR) T-cell manufacturing. For patients with acute myelogenous leukemia (AML), the intensity of chemotherapy received may affect adequate ALC recovery required for CAR T-cell production. We sought to analyze ALC following each course of upfront therapy as one metric for CAR T-cell manufacturing feasibility in children and young adults with AML.ALC data were collected from an observational study of patients with newly diagnosed AML between the ages of 1 month and 21 years who received treatment between the years of 2006 and 2018 at one of three hospitals in the Leukemia Electronic Abstraction of Records Network (LEARN) consortium.Among 193 patients with sufficient ALC data for analysis, the median ALC following induction 1 was 1715 cells/μl (interquartile range: 1166-2388), with successive decreases in ALC with each subsequent course. Similarly, the proportion of patients achieving an ALC400 cells/μl decreased following each course, ranging from 98.4% (190/193) after course 1 to 66.7% (22/33) for patients who received a fifth course of therapy.There is a successive decline of ALC recovery with subsequent courses of chemotherapy. Despite this decline, ALC values are likely sufficient to consider apheresis prior to the initiation of each course of upfront therapy for the majority of newly diagnosed pediatric AML patients, thereby providing a window of opportunity for T-cell collection for those patients identified at high risk of relapse or with refractory disease.

Most children who may benefit from stem cell transplantation lack a matched related donor. Alternative donor transplantations with an unrelated donor (URD) or a partially matched related donor (PMRD) carry an increased risk of graft-versus-host-disease (GVHD) and mortality compared with matched related donor transplantations. We hypothesized that a strategy of partial CD3+/CD19+ depletion for URD or PMRD peripheral stem cell transplantation (PSCT) would attenuate the risks of GVHD and mortality. We enrolled 84 pediatric patients with hematologic malignancies at the Children's Hospital of Philadelphia and the Children's Hospital of Wisconsin between April 2005 and February 2015. Two patients (2.4%) experienced primary graft failure. Relapse occurred in 23 patients (27.4%; cumulative incidence 26.3%), and 17 patients (20.2%) experienced nonrelapse mortality (NRM). Grade III-IV acute GVHD was observed in 18 patients (21.4%), and chronic GVHD was observed and graded as limited in 24 patients (35.3%) and extensive in 8 (11.7%). Three-year overall survival (OS) was 61.8% (95% confidence interval [CI], 50.2% to 71.4%) and event-free survival (EFS) was 52.0% (95% CI, 40.3% to 62.4%). Age ≥15 years was associated with decreased OS (P= .05) and EFS (P= .05). Relapse was more common in children in second complete remission (P = .03). Partially CD3+-depleted alternative donor PSCT NRM, OS, and EFS compare favorably with previously published studies of T cell-replete PSCT. Historically, T cell-replete PSCT has been associated with a higher incidence of extensive chronic GVHD compared with limited chronic GVHD, which may explain the comparatively low relapse and NRM rates in our study cohort despite similar overall rates of chronic GVHD. Partial T cell depletion may expand donor options for children with malignant transplantation indications lacking a matched related donor by mitigating, but not eliminating, chronic GVHD.

The rarity of mixed phenotype acute leukemia (MPAL) has precluded adequate data to incorporate minimal residual disease (MRD) monitoring into therapy. Fluidity in MPAL classification systems further complicates understanding its biology and outcomes; this includes uncertainty surrounding the impact of shifting diagnostic requirements even between iterations of the World Health Organization (WHO) classification. Our primary objective was to address these knowledge gaps. To do so, we analyzed clinicopathologic features, therapy, MRD, and survival in a centrally-reviewed, multicenter cohort of MPAL uniformly diagnosed by the WHO classification and treated with acute lymphoblastic leukemia (ALL) regimens. ALL induction therapy achieved an EOI MRD negative (

BACKGROUND: Fasting hypoglycemia is a recognized occurrence among pediatric patients with acute lymphoblastic leukemia (ALL) during maintenance therapy. Existing publications describing this finding are limited to small studies and case reports. Our objective was to determine the incidence of hypoglycemia during maintenance chemotherapy and to investigate the association of age, as well as other potential risk factors, with this outcome in pediatric patients with ALL. PROCEDURE: This retrospective cohort study included individuals 1 to 21 years of age with ALL treated with antimetabolite-containing maintenance chemotherapy at a large children’s hospital between January 2011 and December 2014. The primary endpoint was time to first documented episode of hypoglycemia during maintenance therapy, defined as single measurement of plasma glucose

Background: The contribution of the gastrointestinal tract microbiome to outcomes after allogeneic hematopoietic cell transplantation (HCT) is increasingly recognized. Investigations of larger pediatric cohorts aimed at defining the microbiome state and associated metabolic patterns pre-transplant are needed. Methods: We sought to describe the pre-transplant stool microbiome in pediatric allogenic HCT patients at four centers. We performed shotgun metagenomic sequencing and untargeted metabolic profiling on pre-transplant stool samples. Samples were compared with normal age-matched controls and by clinical characteristics. We then explored associations between stool microbiome measurements and metabolite concentrations. Results: We profiled stool samples from 88 pediatric allogeneic HCT patients, a median of 4 days before transplant. Pre-transplant stool samples differed from healthy controls based on indices of alpha diversity and in the proportional abundance of specific taxa and bacterial genes. Relative to stool from healthy patients, samples from HCT patients had decreased proportion of Bacteroides, Ruminococcaeae and genes involved in butyrate production, but were enriched for gammaproteobacterial species. No systematic differences in stool microbiome or metabolomic profiles by age, transplant indication or hospital were noted. Stool metabolites demonstrated strong correlations with microbiome composition. Discussion: Stool samples from pediatric allogeneic HCT patients demonstrate substantial dysbiosis early in the transplant course. As microbiome disruptions associate with adverse transplant outcomes, pediatric-specific analyses examining longitudinal microbiome and metabolome change are imperative to identify causal associations and to inform rational design of interventions.

Background Treatment of infants with acute leukemia remains challenging, especially for acute lymphocytic leukemia (ALL). Infants have shown markedly higher rates of induction mortality compared with noninfants. There are limited data on presentation acuity and supportive care utilization in this age group. Methods In retrospective analyses of patients treated for new onset ALL or acute myeloid leukemia (AML) at pediatric hospitals contributing to the Pediatric Health Information System, we compared presentation acuity, induction mortality, and resource utilization in infants relative to noninfants less than 10 years at diagnosis. Results Analyses included 10 359 children with ALL (405 infants, 9954 noninfants) and 871 AML (189 infants, 682 noninfants). Infants were more likely to present with multisystem organ failure compared to noninfants for both ALL (12% and 1%, PR = 10.8, 95% CI: 7.4, 15.7) and AML (6% vs. 3%; PR = 2.0, 95% CI: 1.0, 3.7). Infants with ALL had higher induction mortality compared to noninfants, even after accounting for differences in anthracycline exposure and presentation acuity (2.7% vs. 0.5%, HR = 2.1, 95% CI: 1.0, 4.8). Conversely, infants and noninfants with AML had similar rates of induction mortality (3.2% vs. 2.1%, HR = 1.2, 95% CI: 0.3, 3.9), which were comparable to rates among infants with ALL. Infants with ALL and AML had greater requirements for blood products, diuretics, supplemental oxygen, and ventilation during induction relative to noninfants. Conclusions Infants with leukemia present with higher acuity compared with noninfants. Induction mortality and supportive care requirements for infants with ALL were similar to all children with AML, and significantly higher than those for noninfants with ALL.

Introduction Our objectives were to design and validate methods to identify relapse and hematopoietic stem cell transplantation (HSCT) in children with acute lymphoblastic leukemia (ALL) using administrative data representing hospitalizations at US pediatric institutions. Methods We developed daily billing and ICD-9 code definitions to identify relapses and HSCTs within a cohort of children with newly diagnosed ALL between January 1, 2004, and December 31, 2013, previously assembled from the Pediatric Health Information System (PHIS) database. Chart review for children with ALL at the Children's Hospital of Philadelphia (CHOP) and Texas Children's Hospital (TCH) was performed to establish relapse and HSCT gold standards for sensitivity and positive predictive value (PPV) calculations. We estimated incidences of relapse and HSCT in the PHIS ALL cohort. Results We identified 362 CHOP and 314 TCH ALL patients in PHIS and established true positives by chart review. Sensitivity and PPV for identifying both relapse and HSCT in PHIS were > 90% at both hospitals. Five-year relapse incidence in the 10 150-patient PHIS cohort was 10.3% (95% CI 9.8%-10.9%) with 7.1% (6.6%-7.6%) of children underwent HSCTs. Patients in higher-risk demographic groups had higher relapse and HSCT rates. Our analysis also identified differences in incidences of relapse and HSCT by race, ethnicity, and insurance status. Conclusions Administrative data can be used to identify relapse and HSCT accurately in children with ALL whether they occur on- or off-therapy, in contrast with published approaches. This method has wide potential applicability for estimating these incidences in pediatric ALL, including patients not enrolled on clinical trials.

BACKGROUND AND OBJECTIVES: Acute kidney injury (AKI) is nearly universally associated with worse outcomes, especially among children after hematopoietic stem cell transplant (HCT). Our objective was to examine urinary immune biomarkers of AKI after HCT to provide insights into novel mechanisms of kidney injury in this population. Studying patients undergoing allogeneic (HCT) provides a unique opportunity to examine immune markers of AKI because the risk of AKI is high and the immune system newly develops after transplant. DESIGN, SETTING, PARTICIPANTS: Children (>2 years old) and young adults undergoing their first allogeneic HCT and enrolled in a prospective, observational cohort study at two large children’s hospitals had urine collected pre-HCT and monthly for the first 4 months after HCT. Urine samples at each monthly time point were assayed for 8 immune-related biomarkers. AKI was defined as a 1.5-fold increase in the monthly serum creatinine value which was recorded ±1 day from when the research urine sample was obtained, as compared to the pre-HCT baseline. Generalized estimating equation regression analysis evaluated the association between the monthly repeated measures (urinary biomarkers and AKI). RESULTS: A total of 176 patients were included from two pediatric centers. Thirty-six subjects from one center were analyzed as a discovery cohort and the remaining 140 subjects from the second center were analyzed as a validation cohort. AKI rates were 18–35% depending on the monthly time point after HCT. Urine CXCL10 and CXCL9 concentrations were significantly higher among children who developed AKI compared with children who did not (p

Survival for high-risk neuroblastoma patients is still suboptimal. Although stem cell transplantation (SCT) is used, there is no consensus as to which conditioning regimen has the greatest efficacy and fewest toxicities. We assessed the incidence of and risk for hepatic veno-occlusive disease (VOD) for neuroblastoma patients who underwent autologous SCT with busulfan and melphalan (BuMel) at eight centers following Children's Oncology Group (COG)-based induction chemotherapy. Data regarding the patients, SCT characteristics, busulfan steady-state concentrations, incidence of VOD, and survival were evaluated. VOD was defined using the modified Seattle criteria. Possible factors associated with VOD (age, busulfan-pharmacokinetic parameters, history of hepatic dysfunction, and day of neutrophil engraftment) were evaluated. Seventy five patients were included and 23 children (31%) developed VOD at a median of 19 days after SCT (range 14-27 days). VOD was the cause of death in 4 patients (5%). In a multivariable analysis, young age (OR 1.7 (95% CI: 1.16-2.56; p = 0.012)) and early day of neutrophil engraftment (OR 1.4 (95% CI: 1.08-2.14; p = 0.041) were associated with the development of VOD. Initial or cumulative busulfan steady-state concentration were not associated with VOD. We found that despite the use of intravenous busulfan with adjusted serum levels, the incidence of VOD remains high in pediatric neuroblastoma patients.

Introduction: The most common severe toxicity associated with chimeric antigen receptor T-cells targeting CD19 (CART19) is cytokine release syndrome (CRS; PMID: 29972754). Our group and others have published seminal observations on the biology of CRS through cytokine profiling, measuring a small number of analytes (PMID: 27076371, 33434058). Multiple biomarkers including interferon gamma (IFNG), IL-6, and IL-10 have been associated with the development of severe CRS in previous studies (PMID: 33434058). To date, the only biomarker predictive of the development of CRS prior to infusion has been disease burden. To obtain a more robust understanding of CRS biology, we performed comprehensive secretome profiling to measure more than 1400 serum analytes on serial serum samples collected from patients treated with the 41BB-containing CTL019 on two clinical trials. Methods: Serum from patients enrolled on two clinical trials of the CART19 product CTL019 (NCT01626495 & NCT02906371) were obtained serially from pre-infusion to one month post infusion. Patients were categorised as having "minimal" (no CRS, Grade 1, or Grade 2) or "severe" (Grade 3 or 4) CRS. The serum secretome was profiled using the Olink Explore 1536 Analysis platform (Olink, Upsala, Sweden). 1484 proteins were measured from serum via proximity extension assay (PEA) high-multiplex immunoassay. Differential expression analysis, correlation analyses and receiver operating characteristic (ROC) calculations were performed using R (version 4.0.4) in RStudio. Significance was based on a fold change of greater than 2 or less than -2 and a false discovery rate of less than 0.05 calculated using a Benjamini-Hochberg correction. Results: 26 patients (10 NCT01626495 & 16 NCT02906371) were included comprising 128 unique datapoints from baseline to 35 days post-infusion. Thirteen patients had minimal and 13 had severe CRS. Differentially expressed proteins between minimal and severe CRS at the peak timepoint are shown in (A; green represents IFNG responsive proteins). Not surprisingly, proteins involved in IL-6 and IFNG signalling were increased, including biomarkers of hemophagocytic lymphohistiocytosis (HLH) such as VSIG4, CXCL9, CXCL10, CD163. The IL-18 signalling axis was dysregulated at peak CRS in severe patients with markedly elevated IL18 and IL18BP, despite prior reports suggesting IL-18 up-regulation is unique to the late CRS seen with CART22 (PMID: 32925169). Soluble markers of checkpoint inhibition, including soluble PDL1 (CD274) and LAG3 were also highly elevated. Finally, biomarkers of endothelial damage, such as PLAT, TMSB10 and CALCA were significantly elevated in patients with severe CRS. Pathway analysis revealed significant dysregulation in targetable cytokine, chemokine, and signalling pathways (B). A volcano plot of differentially expressed proteins at pre-infusion (C) identified a single protein, MILR1, as a candidate biomarker that was highly differentially expressed in patients who would subsequently develop severe CRS. MILR1 expression decreased over time (D). An ROC of MILR1 as a predictor for development of severe CRS (E) demonstrated pre-infusion elevated MILR1 could accurately predict development of severe CRS (sensitivity 88%, specificity 97%, AUC=0.977). We identified correlates of MILR1 at pre-infusion and found that MILR1 correlated most highly with soluble FLT3 (R=0.86, p Conclusions: With comprehensive secretome profiling we made multiple novel insights into the biology of CRS after CART19 and identified several potentially targetable proteins and pathways that could mitigate severe CRS. Similar secretome profiling in patients who developed neurotoxicity will also be shown. We identified two novel pre-infusion biomarkers that demonstrate significant capacity to predict the development of severe CRS following CART19 infusion. The inverse relationship apparent between FLT3 and FLT3LG that persists over time is an important finding that implies a potential biological role for FLT3/FLT3 ligand in the development of severe CRS. Mechanistic studies exploring the role of MILR1 and FLT3 in the initiation of CRS are ongoing. Figure 1 Figure 1. Disclosures Lambert: Novartis, shionogi, argenx, Rigel, octapharma: Consultancy; Rigel, Novartis, Sysmex, octapharma: Research Funding. Bassiri: Kriya Therapeutics: Consultancy, Current holder of individual stocks in a privately-held company; Guidepoint Global: Consultancy. Levine: Vycellix: Membership on an entity's Board of Directors or advisory committees; Tmunity Therapeutics: Other: Co-Founder and equity holder; Ori Biotech: Membership on an entity's Board of Directors or advisory committees; Immusoft: Membership on an entity's Board of Directors or advisory committees; Immuneel: Membership on an entity's Board of Directors or advisory committees; Avectas: Membership on an entity's Board of Directors or advisory committees; Akron: Membership on an entity's Board of Directors or advisory committees; In8bio: Membership on an entity's Board of Directors or advisory committees. Maude: Wugen: Consultancy; Novartis Pharmaceuticals Corporation: Consultancy, Research Funding. June: Tmunity, DeCART, BluesphereBio, Carisma, Cellares, Celldex, Cabaletta, Poseida, Verismo, Ziopharm: Current equity holder in publicly-traded company; Novartis: Patents & Royalties; AC Immune, DeCART, BluesphereBio, Carisma, Cellares, Celldex, Cabaletta, Poseida, Verismo, Ziopharm: Consultancy. Barrett: Tmunity Therapeutics: Current Employment. Grupp: Novartis, Kite, Vertex, and Servier: Research Funding; Novartis, Roche, GSK, Humanigen, CBMG, Eureka, and Janssen/JnJ: Consultancy; Novartis, Adaptimmune, TCR2, Cellectis, Juno, Vertex, Allogene and Cabaletta: Other: Study steering committees or scientific advisory boards; Jazz Pharmaceuticals: Consultancy, Other: Steering committee, Research Funding. Teachey: Janssen: Consultancy; NeoImmune Tech: Research Funding; Sobi: Consultancy; BEAM Therapeutics: Consultancy, Research Funding.

Mixed phenotype acute leukemia (MPAL) is a rare group of acute leukemias defined by immunophenotypic expression of more than one hematopoietic cell lineage. The World Health Organization (WHO) diagnostic immunophenotypic criteria for MPAL rely on the intensity of lineage-defining antigen expression, predominantly a qualitative assessment, and are often difficult to apply to a phenotypically heterogeneous leukemia. Cases of MPAL defined by isolated myeloperoxidase (isoMPO) expression on otherwise typical acute lymphoblastic leukemia (ALL) are variably diagnosed as MPAL or ALL based on the incompletely defined criteria for assigning MPO expression. We hypothesized that quantitative criteria for antigen intensity could be developed and applied in a uniform manner across flow cytometry instruments, reagents, and analysis software to enable a consistent approach to diagnosing MPAL and better defining isoMPO. We previously reported on a multicenter cohort identified by respective institutions as MPAL with subsequent central review according to 2008 WHO criteria (Oberley et al 2020). Of these, 100 had suitable dot plots for reevaluation (89: B/Myeloid, 10: T/Myeloid, 1: B/T). Antigen expression was concurrently reviewed by two hematopathologists to reach consensus (BLW, AEK). The cohort was divided a priori into randomly selected training and testing cases (n=30/n=70). Classification criteria were generated in the training cohort for WHO lineage-defining antigen expression (myeloid: cMPO, CD64, CD14; B: CD19, T: cCD3) from 10 cases and then refined through review of an additional 20 cases. Positive antigen expression was classified as maximal intensity approaching that of the mature normal counterpart population (NCP) (cMPO: neutrophils; CD64, CD14 and CD11c: monocytes; CD19: B cells; cCD3: T cells) either by 1) range of expression recapitulating maturation of the NCP, irrespective of the percentage on the leukemic population (Figure 1A); or 2) uniform expression above background on a discrete (sub)population (Figure 1B). To account for technical variation within and among laboratories, maximal antigen intensity on the leukemic population was measured in 0.5 log increments and normalized to the maximal intensity of the NCP. An intensity of ≥50% of the NCP above background was defined as sufficient for MPAL lineage assignment and Using this approach, 41/98 (42%) cases previously classified as MPAL remained classified as MPAL: 31 as B/Myeloid (25 by maturational MPO expression, 6 by maturational CD64 and/or CD14 expression); 9 as T/Myeloid (8 by maturational MPO expression, 1 with maturational CD64, CD14 and CD11c expression); and 1 as B/T. No cases in the cohort showed uniform expression ≥50% of the NCP. The remaining 57 showed isolated low-level MPO expression (maximal intensity Novel semiquantitative immunophenotypic criteria applied to a large cohort of acute leukemias originally diagnosed as MPAL was able to objectively identify a large subset as having dim, uniform MPO expression (isoMPO). Our approach emphasizes antigen expression recapitulating maturational expression similar to their non-leukemic cellular counterparts, normalizes absolute intensities to internal positive and negative control populations to minimize technical variability between observers and assays, and as per the 2017 WHO, does not require a specific percent threshold of positivity. While requiring validation, this is a critical first step toward establishing a reproducible delineation of these complex cases to practically implement the WHO classification to support treatment decisions and ongoing investigation into MPAL genomics and outcomes (available for this cohort by ASH). Figure 1 Figure 1. Disclosures Oberley: Caris LIfe Science: Current Employment. Orgel: Jazz Pharmaceuticals: Consultancy.

Despite the importance of adverse event (AE) reporting, AEs are under-reported on clinical trials. We hypothesized that electronic medical record (EMR) data can ascertain laboratory-based AEs more accurately than those ascertained manually. EMR data on 12 AEs for patients enrolled on two Children’s Oncology Group (COG) trials at one institution were extracted, processed and graded. When compared to gold standard chart data, COG AE report sensitivity and positive predictive values (PPV) were 0–21.1% and 20–100%, respectively. EMR sensitivity and PPV were >98.2% for all AEs. These results demonstrate that EMR-based AE ascertainment and grading substantially improves laboratory AE reporting accuracy.

Black patients with acute myeloid leukemia (AML) experience higher mortality than White patients. We compared induction mortality, acuity of illness prior to chemotherapy, and insurance type between Black and White patients to assess whether acuity of presentation mediates the disparity. Within a retrospective cohort of 1,122 children with AML treated with two courses of standard induction chemotherapy between 2004 and 2014 in the Pediatric Health Information System (PHIS) database, the association between race (Black versus White) and inpatient mortality during induction was examined. Intensive Care Unit (ICU)-level resource utilization during the first 72 hours following admission for initial AML chemotherapy was evaluated as a potential mediator. The total effect of race on mortality during Induction I revealed a strong association (unadjusted HR 2.75, CI: 1.18, 6.41). Black patients had a significantly higher unadjusted risk of requiring ICU-level resources within the first 72 hours after initial presentation (17% versus 11%; RR 1.52, CI: 1.04, 2.24). Mediation analyses revealed the indirect effect of race through acuity accounted for 61% of the relative excess mortality during Induction I. Publicly insured patients experienced greater induction mortality than privately insured patients regardless of race. Black patients with AML have significantly greater risk of induction mortality and are at increased risk for requiring ICU-level resources soon after presentation. Higher acuity amongst Black patients accounts for a substantial portion of the relative excess mortality during Induction I. Targeting factors affecting acuity of illness at presentation may lessen racial disparities in AML induction mortality.

TCRαβ/CD19-depleted HCT has been used with excellent outcomes in pediatric patients with hematologic malignancies, and several studies have demonstrated rapid immune reconstitution in the nonmalignant setting. However, immune recovery following TCRαβ/CD19-depleted hematopoietic cell transplantation (HCT) for malignancy remains incompletely elucidated. Furthermore, the majority of studies to date have used haploidentical and matched unrelated donors. Here we report results of immune reconstitution following TCRαβ/CD19-depleted HCT for hematologic malignancy in 51 pediatric patients with hematologic malignancies, the majority of whom received grafts from unrelated donors. Grafts were from matched unrelated (n = 20), mismatched unrelated (n = 20), and haploidentical (n = 11) donors. The median CD34+ cell dose was 10.2 × 106/kg (range, 4.54 to 20 × 106/kg), and the median TCRαβ+ cell dose was 2.53 × 104/kg (range, 0 to 44.9 × 104/kg). Conditioning was myeloablative with either busulfan or total body irradiation, cyclophosphamide, and thiotepa. Thirty-three patients also received rabbit antithymocyte globulin. No prophylactic post-transplantation immune suppression was routinely given. Forty-three patients received rituximab on day +1 for recipient positive Epstein-Barr virus serology. Forty-nine patients (96%) engrafted with a median time to neutrophil recovery of 13 days (range, 8 to 30 days). Thirty-seven patients (73%) are alive at a median follow-up of 25 months (range, 6 to 50 months). Nine patients (18%) developed grade II-IV acute graft-versus-host disease (GVHD), and 5 patients (11%) developed extensive chronic GVHD. Twenty-six patients (51%) experienced viral reactivation. T cell reconstitution was rapid with significant numbers of CD3+, CD4+, and CD8+ T cells present on first assessment at 4 months post-HCT, and significant numbers of naive CD4+ T cells were present by 8 months post-HCT. Chronic GVHD was associated with delayed T cell recovery; however, T cell reconstitution was not affected by underlying diagnosis, donor source, TCRαβ+ T cell dose, conditioning regimen, or use of antithymocyte globulin. B cell recovery mirrored T cell recovery, and i.v. Ig was discontinued at a median of 8 months (range, 4 to 22 months) post-HCT in patients alive and relapse-free at last follow-up. Immune reconstitution is rapid following TCRαβ/CD19-depleted HCT in pediatric patients with hematologic malignancies. Donor graft source, haploidentical or unrelated, did not affect immune reconstitution. Viral reactivation is common in the first 100 days post-HCT, indicating that improved T cell defense is needed in the early post-HCT period.

Inhibition of precursor B-cell malignancy progression by toll-like receptor ligand-induced immune responses

Background High-dose chemotherapy with autologous stem cell rescue (ASCR) is a key component of high-risk neuroblastoma therapy. Resources required to support patients treated with ASCR conditioning regimens [carboplatin/etoposide/melphalan (CEM) and busulfan/melphalan (BuMel)] have not been directly compared. Procedure An administrative database was used to analyze resource utilization and outcomes in a cohort of high-risk neuroblastoma patients. Patients were followed for 60 days from start of conditioning or until death. Length of hospitalization, length of intensive care unit (ICU) level of care, incidence of sepsis and sinusoidal obstruction syndrome (SOS), and duration of use of specific supportive care resources were analyzed. Results Six of 171 CEM patients and zero of 59 BuMel patients died during the study period (P = 0.34). Duration of hospitalization was longer following BuMel (median 35 vs. 31 days; P = 0.01); however, there was no difference in duration of ICU-level care. Antibiotic use was longer following CEM (median 19 vs. 15 days; P = 0.01), as was antihypertensive use (median 5 vs. 1.6 days; P = 0.0024). Duration of opiate and nonnarcotic analgesic use was longer following CEM early in the study period. Resources consistent with a diagnosis of SOS were used in a higher proportion of BuMel patients. A higher proportion of BuMel treated patients required mechanical ventilation (17% vs. 6%; P = 0.03). Conclusions We used administrative billing data to compare resources associated with ASCR conditioning regimens. CEM patients required more extended use of analgesics, antibiotics, and antihypertensives, while duration of hospitalization was longer, and SOS and the use of mechanical ventilation were more frequent following BuMel.

Graft versus host disease (GVHD) causes significant morbidity and mortality after allogeneic stem cell transplant (SCT). Little is known about genetic determinants of GVHD risk, including human leukocyte antigen (HLA) genotypes outside of HLA-mismatch. HLA-DQ2 and DQ8 genotypes are associated with celiac disease (CD) and are present in ≥90% of patients with CD. Both GVHD and CD are systemic inflammatory conditions that may have T cell-mediated enteropathy. We hypothesized HLA-DQ alleles associated with CD risk would confer increased risks of acute (a) and chronic (c) GVHD in pediatric SCT recipients. We performed a retrospective cohort study of children aged 0-21 years undergoing first allogeneic SCT at the Children's Hospital of Philadelphia from 10/1/12 — 7/1/16. Patients with primary graft failure or missing HLA-DQ genotypes were excluded. We grouped patients by low, moderate or high CD risk (Clin Gastroenterol Hepatol 2009, 7:966). Primary outcomes were 1) 100-day aGVHD incidence; 2) day 100 — 1-year cGVHD incidence; and 3) time to GVHD with relapse, death, secondary graft failure, second SCT, or donor lymphocyte infusion as competing risks. Logistic regressions were used to calculate odds ratios (OR) and 95% confidence intervals (CI). Sub-distribution hazard models were used to estimate crude and adjusted sub-distribution hazard ratios (sHR) in time-to-event analyses. Multivariate models were adjusted for race-ethnicity, malignant/nonmalignant SCT indication, donor/mismatch, and graft source. We identified 167 patients (mean age 9.2 ±6.2 years). Proportions by CD risk were: low-risk n=108 (64.7%), moderate n=33 (19.8%), and high n=26 (15.6%). Day 100 incidence of ≥grade 2 aGVHD was 14.4% (8.4% had ≥grade 3). cGVHD 1-year incidence was 42.7% (14% had extensive). CD risk was protective against GVHD but did not reach statistical significance (Table 1). Risk of clinically significant GVHD (≥grade 2 or any chronic) was reduced in children with CD risk in the adjusted time-to-event model (moderate: sHR 0.42, 95% CI 0.18 — 0.95, p=0.037; high: sHR 0.31, 95% CI 0.12 – 0.8, p=0.016; Figure 1A). The protective effect of high CD risk was more pronounced for severe GVHD (≥grade 3 or chronic extensive) but did not reach statistical significance (adjusted sHR 0.14, 95%CI 0.02-1.09, P = 0.061; Figure 1B). In contrast to our hypothesis, CD risk by HLA-DQ is protective against GVHD in a dose-responsive manner. Reports of HLA-DQ2 and DQ8 protecting against other non-CD autoimmune diseases (rheumatoid arthritis and inflammatory bowel disease) support our observations. These results require confirmation and evaluation in a larger patient sample to define this novel GVHD risk modifier more robustly.

Background Adverse events (AEs) on Children's Oncology Group (COG) trials are reported manually by clinical research assistants (CRAs). The Common Terminology Criteria for Adverse Events (CTCAE) was developed to provide standardized definitions for identifying and grading AEs. The CTCAE has expanded significantly over its five versions, but the impact of CTCAE definitional changes has not been examined. Procedure This study compared AE number and ascertainment among the first four CTCAE versions using a case vignette. Each CTCAE version was used to create a list of AEs and grades by two separate CRAs. Results The CTCAE expanded from 9 categories and 49 AEs in v1.0 to 26 categories and 790 AEs in v4.0. CRAs independently selected different approaches to AE ascertainment-comprehensive and parsimonious. The number of AEs identified in the parsimonious approach was stable with 10-14 in each CTC version. The comprehensive approach identified 9, 20, 29, and 37 AEs in CTC versions 1.0, 2.0, 3.0, and 4.0, respectively. Only approximately 65% of AEs were conclusively graded in versions 2.0 to 4.0 using the comprehensive approach. Conclusions CTCAE has increased in complexity. Although this increased complexity allows for more granular AE reporting, these data demonstrate potential unintended negative consequences of increasing CTC AE complexity, including the risk of varying approaches to AE capture. A comprehensive evaluation of CTC AE definitions and CRA reporting practices across COG institutions and AEs are needed to improve the accuracy and efficiency of AE reporting.

Background Black patients with acute myeloid leukemia (AML) are more likely to present with high acuity and consequently experience higher rates of induction mortality than white patients. Given the consistently identified racial disparities in overall survival (OS) among patients with AML, we aimed to evaluate whether there were sustained on-therapy racial differences in inpatient mortality, intensive care unit (ICU) requirements, or supportive care beyond initial induction. Procedure Within a retrospective cohort of 1239 children diagnosed with AML between 2004 and 2014 in the Pediatric Health Information System (PHIS) database who survived their initial course of induction chemotherapy, we compared on-therapy inpatient mortality, ICU-level care requirements, treatment course duration, cumulative length of hospital stay (LOS), and resource utilization after induction I by race. Results Over the period from the start of induction II through completion of frontline chemotherapy, there were no significant differences in mortality (adjusted odds ratios [OR], 1.01; 95% confidence intervals [CI], 0.41-2.48), ICU-level care requirements (adjusted OR, 0.93; 95% CI, 0.69-1.26), LOS (adjusted mean difference, 3.2 days; 95% CI, -2.3-9.6), or supportive care resource utilization for black patients relative to white patients. Course-specific analyses also demonstrated no differences by race. Conclusion Although black patients have higher acuity at presentation and higher induction mortality, such disparities do not persist over subsequent frontline chemotherapy treatment. This finding allows interventions aimed at reducing disparities to be directed at presentation and induction.

Background High-dose chemotherapy with autologous stem cell rescue (HDC-ASCR) has improved event-free survival for children with high-risk neuroblastoma. Common regimens include carboplatin/etoposide/melphalan (CEM), busulfan/melphalan (BuMel), and tandem HDC-ASCR [thiotepa/cyclophosphamide (TC) followed by CEM]. To complement clinical trial data and to evaluate the clinical burden associated with these regimens, resource ultilization (RU) was evaluated. An administrative database was used to evaluate RU in a previously developed high-risk neuroblastoma cohort. Single CEM and BuMel patients were followed for 60 days from the first day of the HDC-ASCR preparative regimen or until death, whichever came first. Tandem patients were followed from the first day of the first HDC-ASCR preparative regimen through day 60 from the first day of the second HDC-ASCR. Resources compared included inpatient days, ICU-level care, and medications administered. Results A cohort of 578 patients was evaluated; 422 patients underwent single HDC-ASCR with CEM, 67 received BuMel, 72 underwent TC/CEM, and 17 received only the first portion of tandem HDC-ASCR. The median number of inpatient days and days of exposure to antibiotics, opioids, and total parenteral nutrition were higher in the tandem group than in the CEM and BuMel groups. However, the rate of use of several ICU-level resources per 1000 hospital days was lower for the tandem group. Conclusions These data suggest that while patients undergoing tandem HDC-ASCR were hospitalized longer, the severity of illness during hospitalization was not greater in tandem patients.

Background A better understanding of drivers of treatment costs may help identify effective cost containment strategies and prioritize resources. We aimed to develop a method for estimating inpatient costs for pediatric patients with acute myeloid leukemia (AML) enrolled on NCI-funded Phase III trials, compare costs between AAML0531 treatment arms (standard chemotherapy ± gemtuzumab ozogamicin (GMTZ)), and evaluate primary drivers of costs for newly diagnosed pediatric AML. Procedure Patients from the AAML0531 trial were matched on hospital, sex, and dates of birth and diagnosis to the Pediatric Health Information Systems (PHIS) database to obtain daily billing data. Inpatient treatment costs were calculated as adjusted charges multiplied by hospital-specific cost-to-charge ratios. Generalized linear models were used to compare costs between treatment arms and courses, and by patient characteristics. Results Inpatient costs did not differ by randomized treatment arm. Costs varied by course with stem cell transplant being most expensive, followed by Intensification II (cytarabine/mitoxantrone) and Induction I (cytarabine/daunorubicin/etoposide). Room/board and pharmacy were the largest contributors to inpatient treatment cost, representing 74% of the total cost. Higher AML risk group (P = 0.0003) and older age (P

Background Recently investigators have used analysis of administrative/billing datasets to answer clinical and pharmacoepidemiology questions in pediatric oncology. However, the accuracy of pharmacy data from administrative/billing datasets have not yet been evaluated. The primary objective of this study was to determine the concordance of Pediatric Health Information System (PHIS) administrative/billing chemotherapy data with Children's Oncology Group (COG) protocol-mandated chemotherapy and to assess the implications of this level of concordance for further PHIS research. Procedure Data from 384 pediatric patients (1,060 courses of chemotherapy) with acute myeloid leukemia treated on COG clinical trial AAML0531 were previously merged with PHIS data. PHIS chemotherapy administrative/billing data were reviewed for the first three courses of chemotherapy. Accuracy was assessed using three metrics: recognizability of chemotherapy pattern by course, chemotherapy administration pattern by individual medication, and concordance with the number of days of protocol-defined chemotherapy. Results The chemotherapy pattern was recognizable in 87.3% of courses when course-wide accuracy was assessed. Chemotherapy administration pattern varied by medication. Cytarabine had perfect concordance 70.9% of the time, daunorubicin had perfect concordance 77.4% of the time, and etoposide had perfect concordance 67.8% of the time. Conclusions The accuracy of chemotherapy administrative/billing data supports the continued use of PHIS data for epidemiology studies as long as investigators perform data quality control checks and evaluate each specific medication prior to undertaking definitive analyses. Pediatr Blood Cancer 2015;62:1184–1189. © 2015 Wiley Periodicals, Inc.

Background Optimal graft versus host disease (GVHD) prophylaxis prevents severe manifestations without excess immunosuppression. Standard prophylaxis includes a calcineurin inhibitor (CNI) with low-dose methotrexate. However, single-agent CNI may be sufficient prophylaxis for a defined group of patients. Single-agent CNI has been used for GVHD prophylaxis for human leukocyte antigen (HLA)-matched sibling donor (MSD) bone marrow transplants (BMTs) in young patients at the Children's Hospital of Philadelphia for over 20 years. Here, we describe outcomes using this prophylactic strategy in a recent cohort. Procedure We performed a single-institution chart review and retrospective analysis of consecutive children undergoing MSD BMT who received single-agent CNI for GVHD prophylaxis between January 2002 and December 2014. Results Fifty-two children with a median age of 6.1 years (interquartile range [IQR] 2.5–8.3) and donor age of 6 years (IQR 3–10), with malignant and nonmalignant diseases (n = 35 and 17, respectively) were evaluated. Forty-three (82.6%) received oral prophylaxis with single-agent tacrolimus after initial intravenous therapy. Rates of GVHD were consistent with reported rates on dual prophylaxis: the overall incidence of grades 2–4 acute GVHD was 25.5%, grades 3–4 GVHD 9.8%, and chronic GVHD 10.4%. The cumulative incidence of relapse among children with malignancy was 20% at a median of 237 days (IQR 194–318) post-transplant. Two-year overall survival was 82.7% (95% confidence interval [CI]: 69.4–90.6%) and event-free survival was 78.9% (95% CI: 65.1–87.7%). No patient experienced graft failure. Conclusions Single-agent CNI is a safe, effective approach to GVHD prophylaxis in young patients undergoing HLA-identical sibling BMT. Additionally, single-agent oral tacrolimus is a reasonable alternative to cyclosporine in this population.

Background Malnutrition is a pro-inflammatory state, yet data on nutritional risk factors and development of acute graft-versus-host disease (aGVHD) are extremely limited. Procedure We conducted a retrospective cohort analysis of pediatric patients up to age 21 years who underwent allogeneic hematopoietic stem cell transplantation (HSCT) at the Children's Hospital of Philadelphia from January 2011 to September 2014 to determine whether malnutrition was associated with development of aGVHD and early mortality. We identified body mass index (BMI) percentile and serum albumin levels as potential markers of malnutrition and defined two composite nutritional risk variables as any of the following: albumin

Mature B-cell non-Hodgkin lymphoma (B-NHL) constitutes a collection of relatively rare pediatric malignancies. In order to utilize administrative data to perform large-scale epidemiologic studies within this population, a two-step process was used to assemble a 12-year cohort of B-NHL patients treated between 2004 and 2015 within the Pediatric Health Information System database. Patients were identified by ICD-9 codes, and their chemotherapy data were then manually reviewed against standard B-NHL treatment regimens. A total of 1,409 patients were eligible for cohort inclusion. This process was validated at a single center, utilizing both an institutional tumor registry and medical record review as the gold standards. The validation demonstrated appropriate sensitivity (91.5%) and positive predictive value (95.1%) to allow for the future use of this cohort for epidemiologic and comparative effectiveness research.

Background Dexrazoxane may reduce anthracycline-associated cardiotoxicity in pediatric cancer patients. However, concerns of secondary acute myeloid leukemia (AML) have led to restrictions on pediatric dexrazoxane use in Europe. Published data about dexrazoxane-associated secondary AML are limited and conflicting. We sought to estimate the secondary AML risk in children receiving dexrazoxane after anthracycline exposure. Procedure A retrospective cohort of children with newly identified malignancies (excluding AML) receiving anthracyclines between January 1, 1999 and March 31, 2011 was established using the Pediatric Health Information System (PHIS). Patients were followed for all subsequent admissions to identify dexrazoxane exposures and secondary AML, defined by AML ICD-9 codes and AML induction chemotherapy. Logistic regression was used to model the association of dexrazoxane and secondary AML risk. A propensity score was used to adjust for measurable confounding. Results Of 15,532 patients in the cohort exposed to anthracyclines, 1,406 received dexrazoxane. The secondary AML rate was 0.21% (3 of 1,046) in dexrazoxane-exposed and 0.55% (77 of 14,126) in unexposed patients. In a propensity score-adjusted multivariate analysis, dexrazoxane exposure was not associated with an increased risk of secondary AML, OR = 0.38, 95% CI 0.11–1.26. Conclusions Dexrazoxane was not associated with an increased risk of secondary AML in a large cohort of pediatric cancer patients receiving anthracyclines in US hospitals. While these data support dexrazoxane's safety in the general pediatric oncology population, additional studies are needed to confirm these findings and to quantify dexrazoxane's long-term cardioprotective effects. Pediatr Blood Cancer 2015;62:704–709. © 2014 Wiley Periodicals, Inc.

Introduction: Income, education, and health insurance coverage have been shown to influence access to appropriate oncology care, impacting detection and treatment. We sought to evaluate the role of area-based measures of socioeconomic status in contributing to outcome disparities on the two most recent Children's Oncology Group (COG) Phase 3 clinical trials for acute myeloid leukemia (AML), AAML0531 and AAML1031. We hypothesized that pediatric AML patients from low income and low education zip codes have inferior five-year overall survival (OS) and event-free survival (EFS) relative to patients from middle income and more educated zip codes. Methods: Patients enrolled on AAML0531 and AAML1031 were included. Patients with Down syndrome (n=5), FLT3/ITD high allelic ratio (n=264), in AAML1031 Arm D (n=332), and patients whose zip code was not able to be mapped to a US Census area were excluded (n=60). Patients were observed from enrollment on study through last available follow up. Zip code level median annual household income was the primary exposure and was categorized as follows: Poverty: $56,516. Secondary exposures of interest included zip code level educational attainment and insurance type (Medicaid Only vs other insurance) at AML diagnosis. Standard descriptive statistics were used to compare patient characteristics by levels of exposure; the Kaplan Meier method was used to estimate OS (defined as time from study entry to death) and EFS (time from study entry until failure to achieve CR during induction, relapse, or death). Cox proportional hazards models were used to estimate hazard ratios (HR) for OS and EFS. Measures of association were adjusted for known risk factors for mortality including cytogenetic/mutation risk group, gemtuzumab (GO) receipt, race, and age. Logistic regression analyses were used to estimate odds ratios (OR) for early mortality (defined as death during induction). Results: Of 2387 patients enrolled on AAML0531 and AAML1031, 1726 met inclusion criteria for the overall analysis. Due to missing covariate data, 1467 patients were included in the final model. Race/ethnicity differed significantly by area-based income, area-based education, and insurance type with a higher proportion of Black and Hispanic patients living in poverty, low income, and low education areas, and having Medicaid only insurance. Lower area-based income was associated with lower OS (43% in poverty vs. 61% in low income vs. 68% in middle/high income; p = 0.004) and EFS (34% in poverty vs. 46% in low income vs. 54% in middle/high income; p = 0.005), shown in Figure 1. Lower area-based educational attainment was also associated with lower OS (58% in Quartile 4 (lower education) vs. 70% in Quartile 1 (higher education); p = 0.005 across quartiles) and EFS (44% in Q4 vs. 54% in Q1; p = 0.03 across quartiles). Patients with Medicaid Only insurance had lower OS (59 ± 5% vs. 66 ± 3%: p = 0.01) but similar EFS (48 ± 5% vs. 50 ± 3%: p = 0.33). In a full multivariable model, differences in survival by area-based educational attainment and insurance type resolved suggesting that observed crude associations were explained by confounding by area-based income combined with established risk factors. Patients from middle/high income areas experienced 25% lower risk of mortality compared to patients from low income areas (OS: crude HR 0.74 95% CI 0.62, 0.89; adjusted HR 0.79 95% CI 0.63, 0.99) with similar differences in EFS (crude HR 0.79 95% CI 0.69, 0.92; adjusted HR 0.77 95% CI 0.65, 0.89). There was no meaningful confounding of the income-survival association detected as evidenced by unchanged magnitudes of association following adjustment for area-based education, insurance, and established risk factors. Area-based low income was associated with both higher risk of early death (crude OR: 2.43 95% CI 1.04, 5.69) and treatment-related mortality on therapy (11.1 ± 10.5% vs. 3.7 ± 2.5%, p = 0.03) compared to area-based middle/high income. Conclusions: Lower area-based income and education were associated with significantly inferior EFS and OS among patients with AML on the last two Phase 3 COG trials. Moreover, zip-code based low SES is an independent risk factor for mortality in pediatric AML. Additional studies to understand mechanisms of observed socioeconomic disparities in treatment outcomes will inform interventions that may mitigate these inequities. Disclosures Fisher: Pfizer: Research Funding; Astellas: Other: Data Safety Monitoring Board Chair for an antifungal study; Merck: Research Funding.

Background Deaths during induction chemotherapy for pediatric acute lymphoblastic leukemia (ALL) account for one-tenth of ALL-associated mortality and half of ALL treatment-related mortality. We sought to ascertain patient- and hospital-level factors associated with induction mortality. Procedure We performed a retrospective cohort analysis of 8,516 children ages 0 to

Background Limited data exist on induction mortality of pediatric patients with acute promyelocytic leukemia in the United States, usage of all-trans retinoic acid (ATRA) during acute promyelocytic leukemia induction, and the resources needed to deliver induction therapy. Procedure Using the Pediatric Health Information System database we established a retrospective cohort of patients treated for newly diagnosed acute promyelocytic leukemia with ATRA between January 1999 and September 2009 in 32 of 43 PHIS contributing free-standing pediatric hospitals in the United States. Standard statistical methods were used to determine in-hospital induction mortality, ATRA administration, and resource utilization during a 60-day observation period. Results A total of 163 children were identified who met eligibility criteria for cohort inclusion; 52% were female and 76% were white with an average age of 12.7 years. A total of 12 patients (7.4%) died, with 7 (58.3%) dying within the first 7 days of first admission. The mean time to first ATRA exposure increased with decreasing age (P = 0.0016). Resource utilization for management of retinoic acid syndrome was higher than anticipated based on prior studies and differed significantly from patients with non-M3 acute myeloid leukemia. Conclusions The induction mortality for pediatric acute promyelocytic leukemia remains substantial with wide variation in ATRA administration and high rates of resource utilization. Pediatr Blood Cancer 2014;61:68–73. © 2013 Wiley Periodicals, Inc.

Increasing treatment intensity has improved outcomes for children with neuroblastoma. We performed a pilot study in the Children’s Oncology Group (COG) to assess feasibility and toxicity of a tandem myeloablative regimen without total body irradiation (TBI) supported by autologous CD34 selected peripheral blood stem cells. Forty-one patients with high-risk neuroblastoma were enrolled; eight patients did not receive any myeloablative consolidation procedure, and seven received only one. Two patients out of 41 (4.9%) experienced transplant-related mortality. CD34 selection was discontinued after subjects were enrolled due to serious viral illness. From the time of study enrollment, the overall 3-year event-free survival (EFS) and overall survival (OS) were 44.8±9.6% and 59.2±9.2% (N=41). These results demonstrate that tandem transplantation in the cooperative group setting is feasible and support a randomized comparison of single versus tandem myeloablative consolidation with PBSC support for high-risk neuroblastoma.