Children's Oncology Group Trial Research Articles

No evidence that G6PD deficiency affects the efficacy or safety of daunorubicin in acute lymphoblastic leukemia induction therapy.

Anthracyclines are used in induction therapy of pediatric acute lymphoblastic leukemia (ALL) and are known to generate oxidative stress; whether this translates into enhanced antileukemic activity or hemolytic effects in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency is unknown. Among 726 pediatric patients with newly diagnosed ALL treated at St. Jude Children's Research Hospital, 22 had deficient G6PD activity. We compared the prevalence of positive minimal residual disease (MRD) ≥1% at Day 15/Day 19 of induction or ≥0.01% at Day 42/Day 46 (end of induction) and the number of red blood cell (RBC) transfusions after daunorubicin in induction between patients with or without G6PD deficiency, adjusting for ALL risk group, treatment protocol, age, and gender. There was no difference in Day 15/19 (P=1) or end of induction MRD (P=0.76) nor in the number of RBC transfusions (P=0.73); the lack of association with MRD was confirmed in a dataset of 1192 newly diagnosed male patients enrolled in a Children's Oncology Group trial (P=0.78). We found no evidence that G6PD deficiency affects daunorubicin activity during induction treatment for ALL.

Higher Reported Lung Dose Received During Total Body Irradiation for Allogeneic Hematopoietic Stem Cell Transplantation in Children With Acute Lymphoblastic Leukemia Is Associated With Inferior Survival: A Report from the Children's Oncology Group

To examine the relationship between lung radiation dose and survival outcomes in children undergoing total body irradiation (TBI)-based hematopoietic stem cell transplantation (HSCT) for acute lymphoblastic leukemia on the Children's Oncology Group trial. TBI (1200 or 1320cGy given twice daily in 6 or 8 fractions) was used as part of 3 HSCT preparative regimens, allowing institutional flexibility regarding TBI techniques, including lung shielding. Lung doses as reported by each participating institution were calculated for different patient setups, with and without shielding, with a variety of dose calculation techniques. The association between lung dose and transplant-related mortality, relapse-free survival, and overall survival (OS) was examined using the Cox proportional hazards regression model controlling for the following variables: TBI dose rate, TBI fields, patient position during TBI, donor type, and pre-HSCT minimal residual disease level. Of a total of 143 eligible patients, 127 had lung doses available for this analysis. The TBI techniques were heterogeneous. The mean lung dose was reported as 904.5cGy (standard deviation, ±232.3). Patients treated with lateral fields were more likely to receive lung doses ≥800cGy(P<.001). The influence of lung dose ≥800cGy on transplant-related mortality was not significant (hazard ratio [HR], 1.78; P=.21). On univariate analysis, lung dose ≥800cGy was associated with inferior relapse-free survival (HR, 1.76; P=.04) and OS (HR, 1.85; P=.03). In the multivariate analysis, OS maintained statistical significance (HR, 1.85; P=.04). The variability in TBI techniques resulted in uncertainty with reported lung doses. Lateral fields were associated with higher lung dose, and thus they should be avoided. Patients treated with lung dose <800cGy in this study had better outcomes. This approach is currently being investigated in the Children's Oncology Group AALL1331 study. Additionally, the Imaging and Radiation Oncology Core Group is evaluating effects of TBI techniques on lung doses using a phantom.

Adolescent and Young Adult Leukemia and Lymphoma Care Delivery in the Community: Metrics and Outcomes of a Community-Based, Immersive AYA Program

Introduction: Health care delivery programs specific to the needs of adolescents and young adults ages 15-39 (AYAs) with cancer are increasingly being developed in the United States. Guidelines primarily focused on supportive care, fertility and therapeutic regimen for a few cancer types are now established, but best practice metrics and outcome standards are lacking. Malignant hematologic conditions are common in AYAs and challenges of care delivery for this disparate group are accentuated by fragmentation of management within the health system, between pediatric and medical oncology and between academic and community sites. Optimal place of care between academic and community systems is not established, but most of AYAs are diagnosed and cared for in the community. We describe our experience with treating AYAs with acute leukemia and lymphoma in a multi-disciplinary, community-based AYA program, with a focus on metrics and outcomes.Methods: Medical record review under an IRB approved retrospective study was conducted of all AYAs seen by a dedicated AYA Cancer Care team at a single institution in a Southeast United States community. Descriptive analysis was used for demographic data, including age, cancer type, insurance status, gender and ethnicity. Basic statistical analysis was used for guideline and pre-established metrics, including therapy regimens; completion of therapy; study accrual; fertility documentation, referral and intervention; sedated procedures. Kaplan-Meier estimates were applied for newly diagnosed patients for event free and overall survival for each cancer type in newly diagnosed population.Results: Bon Secours St. Francis AYA Cancer Care is an immersive program where a pediatric oncologist is employed by a non-academic, medical oncology, hospital-owned practice that sees 1500 new cancer patients annually and is located in Greenville, SC. Since 2012, AYA Cancer Care has seen 107 patients newly diagnosed, relapsed or in survivorship, 58 (54%) of whom with a diagnosis of acute leukemia or lymphoma. Median age was 25 (range 15-39), and 43%, 31% and 31% were female, minority and uninsured at time of first visit, respectively. Metrics and outcomes for acute lymphoblastic leukemia, acute myelogenous leukemia, Hodgkin lymphoma, and non-Hodgkin lymphoma are shown in Table 1.Despite a high rate of no insurance at diagnosis, all patients received guideline-driven therapy, most were cared for by the AYA team and 65% of LPs/BMAs were sedated with MAC. All newly diagnosed ALL patients except 1 were treated with pediatric-inspired therapy. Males were more likely to be referred to fertility specialists, but females were nearly twice as likely to have intervention in the form of chemoprophylaxis. No Children's Oncology Group trials for indicated cancer types were available via CTSU during the study period, and 31% of patients were enrolled on therapeutic trial, 19% sponsored by biopharmaceutical companies and 12% sponsored by the NCI. EFS and OS for newly diagnosed patients are as follows: AML, 90%/90% (median f/u 40 weeks); ALL, 29%/71% (3.2 yrs); HL, 89%/100% (4.5 yrs); NHL, 89%/100% (5 yrs).Conclusions: We report a high rate of guideline-driven care for AYAs with acute leukemia and lymphoma seen by a multidisciplinary team solely focused on AYA care delivery within a community practice setting. Metrics are derived from best practices from both pediatric (pediatric inspired therapy in AML, ALL; sedation for procedures) and adult (ABVD for HL, NCI and pharma-sponsored trials) oncology paradigms. Immersive AYA programs in non-academic settings are potentially effective models of reducing health disparities and improving outcomes in AYAs. DisclosuresCrosswell:Seattle Genetics: Other: stock ownership in Seattle Genetics.

Glucocorticoids Paradoxically Induce Intrinsic Steroid Resistance through a STAT5-Mediated Survival Mechanism in T-Cell Acute Lymphoblastic Leukemia

▪Upfront resistance to glucocorticoids (GCs) confers a poor prognosis for children with T-cell acute lymphoblastic leukemia (T-ALL). Using primary diagnostic samples from the Children's Oncology Group trial AALL1231, we previously demonstrated that one-third of patient T-ALL samples are intrinsically resistant to GCs when cultured in the presence of interleukin-7 (IL7), a cytokine that is abundant in the T-ALL microenvironment. Furthermore, we demonstrated that inhibiting JAK/STAT signaling downstream of the IL7 receptor (IL7R) with the JAK1/2 inhibitor ruxolitinib (RUX) overcomes GC resistance in these samples. The objective of the present study was to determine the mechanism of IL7-induced GC resistance in T-ALL and to identify novel therapeutic targets to enhance GC sensitivity. We utilized CCRF-CEM cells, a human T-ALL cell line, as a model system in conjunction with primary patient samples. Exposing CCRF-CEM cells to IL7 induced phosphorylation of STAT5, the predominant downstream effector of IL7R signaling. When cultured in the presence of IL7 and the GC dexamethasone (DEX), CCRF-CEM cells recapitulated the IL7-induced GC resistance phenotype observed in patient samples. This resistance could be overcome with RUX, and Bliss index analysis demonstrated a synergistic relationship between DEX and RUX in the presence of IL7. Furthermore, CRISPR/Cas9 mediated knockout of STAT5 (STAT5 KO) was sufficient to overcome resistance, implicating STAT5 as the critical mediator of IL7-induced GC resistance. DEX exposure potently induced upregulation of IL7R expression in CCRF-CEM cells. Using a luciferase reporter construct containing a series of STAT5 response elements, we demonstrated that in the presence of IL7, DEX-induced upregulation of IL7R expression is associated with increased downstream signal transduction, leading to a significant increase in STAT5 transcriptional output. We then performed RNA-seq to further assess the functional consequences of this enhanced STAT5-mediated transcription. Gene set enrichment analysis (GSEA) revealed that STAT5 target genes were significantly upregulated in cells exposed to DEX and IL7 relative to IL7 alone (normalized enrichment score -2.27; p < 0.001; FDR < 0.001), suggesting that DEX exposure augments activation of the STAT5 transcriptional program. One critical component of this program that was induced by the combination of DEX and IL7 was the anti-apoptotic family member BCL2, which was not induced by DEX alone. Further analysis of its protein expression in CCRF-CEM cells confirmed this paradoxical upregulation of BCL2 specifically by the combination of DEX and IL7. Furthermore, BCL2 was not upregulated by DEX and IL7 in STAT5 KO cells, consistent with this being a STAT5-mediated effect. IL7-induced GC resistance could be overcome with shRNA-mediated knockdown of BCL2 and with pharmacologic inhibition of BCL2 by venetoclax. Similar to the effect observed with RUX, Bliss index analysis demonstrated synergy between DEX and venetoclax in the presence of IL7. Consistent with our observations in CCRF-CEM cells, an analysis of primary diagnostic T-ALL samples revealed DEX-induced upregulation of IL7R expression in samples with IL7-induced GC resistance, which was associated with increased BCL2 expression in the presence of DEX and IL7. Finally, we performed a similar analysis in healthy murine thymocytes, and found that CD4/CD8 double negative (DN) and CD4 or CD8 single positive (SP) thymocytes, but not double positive (DP) thymocytes, exhibited profound IL7-induced GC resistance that was associated with DEX-induced upregulation of IL7R expression and increased BCL2 expression in the presence of DEX and IL7. These data are consistent with the known role of IL7 specifically at the DN and SP stages of development, and suggests that IL7-induced GC resistance is a physiologic mechanism of GC resistance in normal thymocyte development that is retained during leukemogenesis in a subset of T-ALL samples. Taken together, these data demonstrate that GCs paradoxically induce their own resistance in a subset of T-ALLs and in normal developing T-cells by augmenting a STAT5-mediated pro-survival program that results in upregulation of BCL2. Furthermore, we demonstrate that inhibition of JAK/STAT signaling or of BCL2 may have considerable therapeutic benefit to enhance GC sensitivity in T-ALL patients with IL7-induced GC resistance. DisclosuresTeachey:La Roche: Consultancy; Amgen: Consultancy.

Conformal Radiation Therapy for Pediatric Patients with Low-Grade Glioma: Results from the Children's Oncology Group Phase 2 Study ACNS0221

To determine the rate of marginal relapse, progression-free survival (PFS), and overall survival (OS) in patients with pediatric low-grade glioma (PLGG) treated with conformal radiation therapy (CRT) with a clinical target volume (CTV) margin of 5mm in the Children's Oncology Group trial ACNS0221. Patients aged 3 to 21years with unresectable progressive, recurrent, or residual PLGG were eligible for this study. Patients younger than 10years were required to have received at least 1 chemotherapy course. Patients with neurofibromatosis type I were not eligible. All patients underwent magnetic resonance imaging-based planning and received 54Gy CRT in 30 fractions with a 5-mm CTV margin. Of 85 eligible patients (median age, 13.6years) treated between March 2006 and December 2010, 14 were younger than 10years and 36 received prior chemotherapy. Sixty-six had pilocytic astrocytoma, 15 had other histologic subtypes, and 4 had unbiopsied chiasmatic lesions. Events included 23 relapses (19 central, 4 distant, and no marginal) and 7 deaths. At a median follow-up of 5.15years, 5-year PFS was 71%±6% andOS was 93%±4%. Male sex (P=.068) and large tumor size (P=.050) trended toward significance for association with decreased PFS. Age, histology, tumor location, time between diagnosis and study entry, and MIB-1 status were not associated with PFS.OS was negatively associated with male sex (P=.064), non-pilocytic astrocytoma histology (P=.010), and large tumor size (P=.0089). For patients with PLGG, CRT with a CTV margin of 5mm yields an acceptable PFS and does not lead to a high rate of marginal relapse.

Survival by age in children and adolescents with Hodgkin lymphoma: A pooled analysis of Children’s Oncology Group (COG) trials.

7543 Background: The National Cancer Institute defines adolescent/young adult as 15-39y. Guidelines from ASCO and Friends of Cancer Research call for including children ≥12y on late phase trials spanning children and adults. We examined whether, in children and adolescents receiving response-based therapy for Hodgkin lymphoma (HL), age ≥12y would define a group with inferior outcomes compared to younger patients. Methods: This was a pooled analysis of individual patient-level data from three COG Phase 3 trials for intermediate, low, high-risk HL (AHOD0031, AHOD0431, AHOD0831). 5-yr event free survival (EFS) and overall survival (OS) by age were estimated via Kaplan Meier method. Cox regression models examined the influence of age on EFS and OS, adjusted for race/ethnicity, sex, insurance, histology, Ann Arbor stage, B symptoms, bulk, study, and radiation therapy (RT). Results: We included 2071 of 2155 patients, 1-21y enrolled from 2002 -2012. Mean age at diagnosis was 14.6y (±3.5) with 54% ≥15y (N = 1121) and 81% ≥12y (N = 1684). At median follow-up of 6.9 years, patients < 15y had statistically significantly better EFS ( < 15y: 85% vs. ≥15y: 80%, p = 0.02). A difference in EFS was noted in those < 12y vs. ≥12y (87% vs. 81%, p = 0.0503). OS was significantly better in patients < 15y vs. ≥15y (98% vs. 95%, p = 0.006), but did not differ in < 12y vs. ≥12y (99% vs. 97%, p = 0.136). Cumulative incidence of second malignant neoplasm did not differ by age category. In multivariable models, older age was an independent predictor of treatment failure in both age categories (Table). Conclusions: With contemporary, response-based therapy on COG trials, adolescents ≥12 and ≥15y had worse EFS than younger groups. This suggests that children ≥12y may benefit from therapy escalation and inclusion in late phase trials of novel agents incorporating antibody drug conjugates or checkpoint inhibitors. Multivariable cox model of 5-yr EFS and OS by age group. 5-yr EFS 5-yr OS HR 95% CI p-value HR 95% CI p-value < 12 years (R: ≥12) 0.71 (0.51, 0.98) 0.04 0.51 (0.2, 1.34) 0.17 < 15 years (R: ≥15) 0.74 (0.59, 0.93) 0.01 0.39 (0.2, 0.76) 0.006 HR: hazard ratio; 95%CI: 95% confidence interval; R: reference group

Timing of Radiation Therapy in Pediatric Wilms Tumor: A Report From the National Cancer Database

Todetermine, using the National Cancer Database (NCDB), the impact of the surgery to radiation therapy interval (SRI) on survival in contemporary patients with Wilms tumor (WT). The NCDB was queried for patients aged ≤25years diagnosed from 2004 to 2013 with unilateral WT who underwent definitive surgery and radiation therapy. The SRI was calculated for each patient. A stratified analysis was performed based on presence of metastasis using logistic regression to calculate risk factors for prolonged SRI, with a focus on the recommended SRI according to recent Children's Oncology Group trials (by day 14) and National Wilms Tumor Study-5 (by day 9). Cox regression was performed to assess the association of SRI with overall survival. A total of 1488 patients were included; 32.1% had metastasis at diagnosis. Among both metastatic and nonmetastatic groups, older patients were more likely to have prolonged SRI. For those without metastasis, SRI > 14days was associated with increased risk of mortality (hazard ratio 2.13, P = .013). Analyzing SRI as a continuous variable also demonstrated an increased risk of death with longer SRI (hazard ratio 1.04 per day, P=.006) in this group. In contrast, among patients with metastasis, no significant association between SRI and mortality was found. Early initiation of radiation therapy remains a critical component of multimodal treatment for patients with nonmetastatic WT. For nonmetastatic patients, SRI ≤ 14days correlates with improved overall survival. However, no such association was noted for patients with metastases. These results may inform the development of future WT trials.

Pediatric oncology clinical trial participation where the geography is vast: Development of a clinical research system for tertiary and satellite centers in Ontario, Canada.

Opportunities for participation in clinical trials are a core component of the care of children with cancer. In Ontario, many pediatric patients live long distances from their cancer center. This paper describes the work that was done in order to allow patients participating in Children's Oncology Group trials to receive care, including research protocol related care, jointly between the tertiary pediatric cancer center and the closer-to-home satellite center. The system is a pragmatic risk-based model, supporting excellence in care while ensuring good conduct of the research in compliance with applicable regulations and guidelines, including ethics oversight.

Outcomes in adolescents and young adults with Hodgkin lymphoma treated on US cooperative group protocols: An adult intergroup (E2496) and Children's Oncology Group (COG AHOD0031) comparative analysis

There is no clear consensus between pediatric and adult providers about the treatment of adolescents and young adults (AYAs) with Hodgkin lymphoma (HL). Failure-free survival (FFS) and overall survival (OS) were compared between 114 patients ages 17 to 21 years with HL who were treated on the Eastern Cooperative Oncology Group-American College of Radiology Imaging Network Intergroup adult E2496 study and 391 similarly patients ages 17 to 21 years with HL who were treated on the pediatric Children's Oncology Group (COG) AHOD0031 study. Comparing AYAs from the COG and E2496 studies, there were no significant differences in extralymphatic disease, anemia, or hypoalbuminemia. More AYAs in the E2496 trial had stage III and IV disease (63% vs 29%; P < .001) and B symptoms (63% vs 27%; P < .001), and fewer had bulk disease (33% vs 77%; P < .001). More AYAs on the COG trial received radiotherapy (76% vs 66%; P = .03), although in smaller doses. E2496 AYA The 5-year FFS and OS rates were 68% and 89%, respectively in the E2496 AYAs and 81% and 97%, respectively, in the COG AYAs, indicating a statistically superior compared in the COG AYAs (P = .001). In stratified multivariable analyses, E2496 AYAs had worse FFS than COG AYAs in all strata except patients who had stage I and II HL without anemia. Propensity score analysis (based on stage, anemia, and bulk disease) confirmed inferior FFS for E2496 AYAs compared with COG AYAs (P = .004). On the E2496 study, FFS was significantly divergent across age groups (P = .005), with inferior outcomes for those ages 17 to 21 years versus 22-44 years. There was no difference across age on the COG study. Younger AYA patients with HL appear to have better outcomes when treated on a pediatric trial than patients of similar age on an adult trial. Prospective studies examining these differences are warranted. Cancer 2018;124:136-44. © 2017 American Cancer Society.

Historical time to disease progression and progression-free survival in patients with recurrent/refractory neuroblastoma treated in the modern era on Children's Oncology Group early-phase trials.

Early-phase trials in patients with recurrent neuroblastoma historically used an objective "response" of measureable disease (Response Evaluation Criteria In Solid Tumors [RECIST], without bone/bone marrow assessment) to select agents for further study. Historical cohorts may be small and potentially biased; to the authors' knowledge, disease recurrence studies from international registries are outdated. Using a large recent cohort of patients with recurrent/refractory neuroblastoma from Children's Oncology Group (COG) modern-era early-phase trials, the authors determined outcome and quantified parameters for designing future studies. The first early-phase COG trial enrollment (sequential) of 383 distinct patients with recurrent/refractory neuroblastoma on 23 phase 1, 3 phase 1/2, and 9 phase 2 trials (August 2002 to January 2014) was analyzed for progression-free survival (PFS), overall survival (OS), and time to disease progression (TTP). Planned frontline therapy for patients with high-risk neuroblastoma included hematopoietic stem cell transplantation (approximately two-thirds of patients underwent ≥1 hematopoietic stem cell transplantation); 13.2% of patients received dinutuximab. From the time of the patient's first early-phase trial enrollment (383 patients), the 1-year and 4-year PFS rates ( ± standard error) were 21% ± 2% and 6% ± 1%, respectively, whereas the 1-year and 4-year OS rates were 57% ± 3% and 20% ± 2%, respectively. The median TTP was 58 days (interquartile range, 31-183 days [350 patients]); the median follow-up was 25.3 months (33 patients were found to be without disease recurrence/progression). The median time from diagnosis to first disease recurrence/progression was 18.7 months (range, 1.4-64.8 months) (176 patients). MYCN amplification and 11q loss of heterozygosity were prognostic of worse PFS and OS (P = .003 and P<.0001, respectively, and P = .02 and P = .03, respectively) after early-phase trial enrollment. This recent COG cohort of patients with recurrent/refractory neuroblastoma is inclusive and representative. To the authors' knowledge, the current study is the first meta-analysis of PFS, TTP, and OS within the context of modern therapy. These results will inform the design of future phase 2 studies by providing a) historical context during the search for more effective agents; and, b) factors prognostic of PFS and OS after disease recurrence to stratify randomization. Cancer 2017;123:4914-23. © 2017 American Cancer Society.

Disease Characteristics and Prognostic Implications of Cell-Surface FLT3 Receptor (CD135) Expression in Pediatric Acute Myeloid Leukemia: A Report from the Children's Oncology Group.

Purpose: The FLT3 cell-surface receptor tyrosine kinase (CD135) is expressed in a majority of both acute lymphoid leukemia (ALL) and myeloid leukemia (AML). However, the prognostic significance of CD135 expression in AML remains unclear. We therefore evaluated the association between FLT3 surface expression and disease characteristics and outcomes in pediatric patients with AML.Experimental Design: We analyzed FLT3 receptor expression on AML blasts by multi-dimensional flow cytometry and its association with disease characteristics, clinical outcomes, and FLT3 transcript level in 367 children with AML treated on the Children's Oncology Group trial AAML0531.Results: There was high variability in blast CD135 cell-surface expression across specimens. CD135 expression measured by flow cytometry was not correlated with FLT3 transcript expression determined by quantitative RT-PCR. Overall, CD135 expression was not significantly different for patients with FLT3/WT, FLT3/ITD, or FLT3/ALM (P = 0.25). High cell-surface CD135 expression was associated with FAB M5 subtype (P < 0.001), KMT2A rearrangements (P = 0.009), and inversely associated with inv(16)/t(16;16) (P < 0.001). Complete remission rate, overall survival, disease-free survival, and relapse rates were not significantly different between patients with low and high CD135 expression.Conclusions: FLT3 cell-surface expression did not vary by FLT3 mutational status, but high FLT3 expression was strongly associated with KMT2A rearrangements. Our study found that there was no prognostic significance of FLT3 cell surface expression in pediatric AML. Clin Cancer Res; 23(14); 3649-56. ©2017 AACR.

Children’s Oncology Group (COG) clinical trials as exemplars of pragmatism in clinical research.

e18188 Background: In 2016, President Obama announced the “Moonshot Cancer Initiative” to advance cancer research. One of the key components of this initiative is promoting enrollment in pragmatic clinical trials and data sharing. As described in 2009 by Thorpe et al, using the 9-domian PRECIS-2 tool, a ‘pragmatic’ trial, as opposed to an ‘explanatory’ trial used to confirm a physiologic hypothesis, is one in which the intervention can be immediately applied into real-world clinical practice (J of Clin Epi:2009). In the US, 60%-90% children are enrolled on COG research trials. State-of-the-art treatment for a child is derived from superior therapy identified in prior trials which then serves as the standard arm of subsequent phase-III trials and becomes the de facto practice guideline and ‘standard of care’ .To accomplish this goal, COG shares its data among the 242 member institutions.Our objective is to assess “pragmatism” in COG trials. Methods: We analyzed the 158 COG phase III clinical trials between 2006-2016 for all 9 domains of the PRECIS-2 (Table 1) and graded them from 1-5 (most explanatory to most pragmatic). Results: Out of 152 phase III clinical trials on the COG website, 138 (91%) scored 5/5 for all 9 PRECIS pragmatic domains and 148 (98%) scored &gt;4. The scoring for all 9 domains is in table 1. Conclusions: COG provides nearly all children in the United States access to pragmatic phase III research as outlined in the Moonshot Goals. Goal of merging evidence-based standard care accessible to all and conducting well- designed clinical research to identify the best therapies has been accomplished by COG and should serve as an example to other cancer organizations. 9 domains of PRECIS-2 to assess pragmatism in clinical trials. [Table: see text]

Genetics of ancestry-specific risk for relapse in acute lymphoblastic leukemia.

The causes of individual relapses in children with acute lymphoblastic leukemia (ALL) remain incompletely understood. We evaluated the contribution of germline genetic factors to relapse in 2,225 children treated on Children’s Oncology Group trial AALL0232. We identified 302 germline single nucleotide polymorphisms (SNPs) associated with relapse after adjusting for treatment and ancestry and 715 additional SNPs associated with relapse in an ancestry-specific manner. We tested for replication of these relapse-associated SNPs in external data sets of antileukemic drug pharmacokinetics and pharmacodynamics and an independent clinical cohort. 224 SNPs were associated with rapid drug clearance or drug resistance, and 32 were replicated in the independent cohort. The adverse risk associated with black and Hispanic ancestries was attenuated by addition of the 4 SNPs most strongly associated with relapse in these populations [for blacks: model without SNPs hazard ratio (HR) =2.32, P=2.27×10−4, model with SNPs HR=1.07, P=0.79; for Hispanics: model without SNPs HR=1.7, P=8.23×10−5, model with SNPs HR=1.31, P=0.065]. Relapse SNPs associated with asparaginase resistance or allergy were overrepresented among SNPs associated with relapse in the more asparaginase intensive treatment arm (20/54 in Capizzi-methorexate arm vs. 8/54 in high-dose methotrexate arm, P=0.015). Inherited genetic variation contributes to race-specific and treatment-specific relapse risk.

Down Syndrome AML Is Unique in Phenotype Both at Diagnosis and in Post Chemotherapy Regeneration

Abstract Background: Down syndrome (DS) acute myeloid leukemia (DS-AML) is predominantly found in young children (under the age of 4) and responds well to chemotherapy. The difference in clinical features suggests that despite the predominance of megakaryoblastic disease, DS-AML blasts are different from non-DS AML blasts with megakaryoblastic morphology (AMKL). The immunophenotypes of DS-AML blasts at diagnosis were compared to those of non-DS AML patients using unsupervised hierarchical clustering analysis (HCA) and assessed for their immunophenotypic overlap with known morphologic subgroups. In addition, residual disease monitoring of non-DS AML patients using "Difference from Normal" flow cytometry has been applied to DS-AML with unexpected results. Methods: A standardized antibody panel was used to define quantitative gene product (antigen) expression in bone marrow (BM) specimens from patients with AML at diagnosis and following chemotherapy. The quantitative phenotypic expression of multiple cell surface markers and physical characteristics defined a position in 15 dimensional data space for each patient. HCA was performed to mathematically cluster DS-AML patients enrolled on Children's Oncology Group study AAML1531 with non-DS patients from study AAML0531 based on 15 dimensional profiles. Five patients with DS who were older than 4 years of age and therefore treated on AAML0531 were also included. Data regarding morphology were appended to the data set. The same antibody panel was used to assess measurable residual disease (MRD) in 147 follow up BM aspirates from 50 DS patients ages 1 to 21 undergoing treatment for either AML or B-ALL (n=46, n=4 respectively) who were not included in the clinical studies. When possible, cell sorting was performed for FISH or SNP/CGH microarray studies. Results: Diagnostic Clustering: HCA of 17 DS-AML diagnostic phenotypes with 769 non-DS AML patients revealed a tight immunophenotypic correlation between 12 (71%) DS-AML patients (Figure 1). Further analysis of this diagnostic subset showed a consistent mean antigen expression profile that was distinct from non-DS AML diagnostic phenotypes. Similarly, the DS-AML patients clustered separately from the 5 older DS patients (&gt;4 years of age) with AML, who were treated on AAML0531 and exhibited consistently different identifying diagnostic markers despite the shared constitutional trisomy 21. Additionally, the phenotype associated with the DS-AML cluster does not match that of patients with AMKL morphology. The largest immunophenotypic cluster of non-DS patients with AMKL morphology were classified with the RAM phenotype[1], which segregate into a mathematically unique branch of the dendogram distinct from the DS-cluster. Observation of a consistent DS-specific non-leukemic myeloid regenerative phenotype: Of the 147 post chemotherapy specimens submitted for MRD analysis off clinical study, 141 (96%) had a clearly identifiable CD34+/CD56+ population present between 0.06-6.0% total non-erythroid composition. A second abnormal population expressing CD34+ but not HLA-DR was also observed in these patients but at a lower level (0.02-2.66%) compared to the CD34+/CD56+ cell population. Two patients had a reproducible absence of 56+, DR- progenitors across all follow up specimens (6/147) and may represent unique clinical cases with disease features beyond our knowledge. In four DS patients undergoing treatment for B-ALL, the same immunophenotypic features (CD34+/CD56+ and negative HLA-DR) were observed. Genetic data: In 4 cases, cell sorting of CD34+/CD56+ post treatment progenitors revealed a lack of cytogenetic markers present in the clone of leukemic blasts at diagnosis. Conclusions: The blasts of patient with typical DS-AML (i.e under the age of 4 years at diagnosis) are immunophenotypically distinct from those of non-DS-AML patients and exhibit consistent immunophenotypic features that differ from DS patients with AML who are older than 4 years of age. The normal myeloid progenitors in DS patients who have undergone chemotherapy for AML or ALL express an immunophenotype that is different from normal BM of non-DS patients recovering from chemotherapy. [1] Brodersen, Lisa Eidenschink, et al. "A Recurrent Immunophenotype at Diagnosis Independently Identifies High Risk Pediatric AML: A Report from the Children's Oncology Group Trial AAML0531." Disclosures Wilson: Hematologics: Employment. Brodersen:Hematologics: Employment. Zehentner:Hematologics: Employment, Equity Ownership. Pardo:Hematologics, Inc: Employment. Wells:Hematologics: Employment, Equity Ownership. Loken:Hematologics: Employment, Equity Ownership.

Mutational Concordance from Diagnosis and Relapse in Pediatric Acute Myeloid Leukemia: A Report from the Children's Oncology Group

The range of genomic drivers of leukemogenesis and clonal nature of the disease illustrate the heterogeneity of the mutational spectrum in AML. Genomic interrogation of the evolution of AML has begun to highlight the scope of somatic changes that occur between diagnosis and relapse. A total of 1,214 patients were treated on the Children's Oncology Group trials AAML03P1 and AAML0531, of which 398 had relapse after initial remission. Of this cohort, 201 patients had matching diagnostic and relapse specimens for molecular profiling for the most common somatic mutations in pediatric AML (FLT3/ITD, FLT3/ALM, NPM1, CEBPA, WT1, NRAS, and KIT). Sequencing techniques included PCR with Sanger sequencing for detection of point mutations and indels and fragment length analysis for FLT3/ITD.In the cohort, FLT3/ITD was detected in 31/201 (15%) cases at diagnosis. Of the cases with diagnostic ITD, 22 (71%) relapsed with FLT3/ITD. Conversely, of the 28 cases with FLT3/ITD detected at relapse, 6 (21%) did not have detectable ITD at diagnosis. Overall, there were 37 patients (18%) with FLT3/ITD mutations detected at either time point. Of the 37 patients, 22 (59%) demonstrated stability of the mutation from diagnosis to relapse. Discordant mutation status was observed in 15 patients (41%). Among the discordant patients, 9 had FLT3/ITD detected at diagnosis only. Conversely, 6 patients were ITD-positive at relapse only, demonstrating disease evolution with continued mutational acquisition (Table 1). In every discordant case, ultra sensitive PCR analysis confirmed absence of an ITD. The median ITD allelic ratio (AR) for patients with concordant status was 0.47 (range 0.03-2.67) vs. 0.24 (range 0.04-0.47) for those with disappearance of the ITD at relapse, suggesting an association of diagnostic AR with mutation stability.NPM1 mutations were detected in 8 patients at diagnosis and 100% concordance was observed in the cohort. CEBPA mutations were detected in 6 patients at diagnosis, and in 5 cases remained at relapse. One patient had a CEBPA mutation detected at diagnosis only. FLT3/ALM mutations were detected in 7 patients at either time point. Seven patients had an ALM at diagnosis, however concordance was observed in 2 cases, whereas 4 patients had detection at diagnosis only.There were 22 patients (11%) with NRAS mutations detected at either time point. Diagnostic NRAS mutations were detected in 18 patients, while only 3 (17%) had the identical mutation detected at relapse, as one patient had a distinct mutational sequence present at relapse. NRAS mutations were detected at diagnosis only in 13 patients (59%), where as 5 patients (23%) had a mutation detected at relapse only. NRAS was the most discordant mutations analyzed, with only 3/22 patients (14%) demonstrating stability of the mutation from diagnosis to relapse (Table 1).WT1 exon 17 indels were observed in 24 patients (12%) at either time point. Nineteen patients had diagnostic mutations, with 18 patients demonstrating stability at relapse. Five patients had mutations detected at relapse only. Overall, concordance was observed in 18 patients (75%). Only 1 alteration was detected at diagnosis in all patients, however 6 patients with concordant WT1 status had multiple indels detected at relapse, demonstrating continued mutational acquisition. KIT mutations (missense and indels) in exons 8 (n=11) and 17 (n=7) were detected in 17 patients. Mutational concordance was observed in 7 patients. Eight patients had mutations detected at diagnosis only, while 2 patients had mutations detected at relapse only (Table 1).We demonstrate the complexity of the evolving somatic landscape from diagnosis to relapse in pediatric AML. The stability of NPM1 mutations, considered an early leukemogenic event, is in contrast to the discordant NRAS and KIT mutations. There was evolution of FLT3/ITD status, and we observed overall higher ARs in the concordant cohort, perhaps suggesting mutations in this cohort served as stronger leukemic drivers. Further investigation on the biologic implications and clonal prevalence is critical to determine a mutation's significance in leukemogenesis, timing of acquisition, and if appropriate for therapeutic targeting and disease monitoring. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Prognostic Significance of 11q23/MLL Fusion Partners in Children with Acute Myeloid Leukemia (AML) - Results from the Children's Oncology Group (COG) Trial AAML0531

Background: Rearrangement of chromosome 11q23 at KMT2A (MLL+) occurs in ~20% of childhood acute myeloid leukemia (AML) cases and is the most common recurrent cytogenetic abnormality in childhood AML. More than 80 fusion partners of MLL have been characterized and the prognostic impact varies by partner and additional cytogenetic aberrations (ACAs). We previously reported superior event-free-survival (EFS), overall survival (OS), relapse risk (RR) and disease free survival (DFS) for patients with MLL+ on AAML0531 treated with gemtuzumab ozogamicin (GO). The impact of fusion partners has not been described for this trial cohort.Objective: To determine the impact of 11q23/MLL+ fusion partners on outcomes for children with AML who were treated uniformly on AAML0531.Methods: AAML0531 (2006 - 2010) was a randomized phase 3 trial of GO with conventional chemotherapy for children, adolescents, and young adults, ages 0 to 29 years, with de novo AML. The trial enrolled 1022 eligible patients without Down syndrome, and cytogenetic data was available for 988 patients. Of those, 215 (21.8%) were classified as 11q23/MLL+ after central cytogenetic review. The majority of patients with 11q23/MLL+ AML (n=200, 93%) were classified as intermediate risk (IR) and a minority (n=15, 7%) were classified as high risk (HR) based upon high FLT3 internal tandem duplication allelic ratio (FLT3-ITD-AR), monosomy 5/5q deletion, monosomy 7, or >15% blasts by morphology following Induction (Ind) I. HSCT was performed for 30 patients (14%).We defined 11q23/MLL+ subgroups for partners identified in ≥5 cases. Partners in <5 cases were grouped as "other"; unidentified fusions were classified as "unknown". Outcomes of minimal residual disease (MRD) at end of Ind I and complete remission (CR) at end of Ind II, 5-yr EFS and OS from study entry, and 5-yr RR from end of Ind II for patients in CR were compared across subgroups. Univariable and multivariable analyses were performed.Results: The median age for the 11q23/MLL+ cohort was 2.5 years and the distribution was equally male and female. The majority of cases (n=175, 81%) were classified into 8 specific partner subgroups, and the remaining cases were classified as other (n=30, 14%) or unknown (n=10, 5%). The most common translocation was t(9;11)(p22;q23) (n= 82, 38%). Central nervous system involvement was rare (<10% overall and in every subgroup). While extramedullary chloromas were rare (7% overall), chloromas were reported in 83% (n=5) of t(10;11)(p11.2;q23), 40% (n=16) of t(10;11)(p12;q23), and 27% (n=4) of t(6;11)(q27;q23). ACAs were observed in 86 of 211 cases (41%) that underwent central review. ACAs were numerical in 54 cases (26%), most commonly trisomy 8 (n=30, 14%) and structural + numerical in 32 cases (15%), most commonly involving chromosome 1 (n=11, 34%). Molecular findings for 3 studied genes were rare: High FLT3-ITD-AR n=4; NPM1 n=1; CEBPA n=0.Clinical outcomes varied significantly by fusion partner and poorer OS was primarily due to relapse (Table 1). CR rate was 86% overall and did not vary by subgroups. MRD was detected in 21% overall and was most common in t(1;11)(q21;q23) and t(6;11)(q27;q23). Complex karyotype (≥3 abnormalities) was seen in 52 cases (25%) and predicted inferior outcome compared to <3 abnormalities (5-yr EFS 29% vs. 41%, p=0.02; 5-yr OS 44% vs. 63%, p=0.001, respectively). Chromosome 1 abnormalities were associated with very poor outcomes, 5-yr EFS 19% and 5-yr OS 29%. The most unfavorable partners for EFS were t(6;11)(q27;q23), t(10;11)(p11.2;q23), t(10;11)(p12;q23), and t(11;19)(q23;p13.3)(Figure 1). In multivariable comparison to patients with t(9;11)(p22;q23), the former 3 groups maintained inferior EFS (HR 2.51, p=0.006; HR 3.10, p<0.001; HR 2.15, p=0.002, respectively) and OS (HR 2.56, p=0.017; HR 4.8, p=0.006; HR 2.14, p=0.016, respectively).Conclusions: Fusion partners critically impact the prognosis of 11q23/MLL+ AML. In this large, uniformly treated cohort, t(6;11)(q27;q23), t(10;11)(p11.2;q23) and t(10;11)(p12;q23) were independently associated with inferior EFS and OS. Children with these unfavorable partners are at high risk for relapse and allogeneic HSCT should be considered in first CR. Complex karyotype, chromosome 1 aberrations, and extramedullary chloromas were additional adverse prognostic factors. Work is ongoing to confirm these results in the subsequent COG trial, AAML1031. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Minimal Residual Disease Assessment of Remission after Induction Therapy Is Superior to Morphologic Assessment for Risk Stratification in Childhood Acute Lymphoblastic Leukemia: A Report from the Children's Oncology Group (COG)

▪Background: Minimal residual disease (MRD) assessment after initial therapy is integral to modern risk stratification in both precursor B and T lineage acute lymphoblastic leukemia (B-ALL and T-ALL). While MRD is used to determine depth of remission, remission is still defined, both in clinical practice and clinical trials, according to morphological assessment. We aimed to determine the outcomes of children, adolescents and young adults with discordant assessments of remission by morphology vs. by MRD, and in doing so, the extent to which morphologic assessment of remission contributes to risk assessment in this population.Methods: We identified a cohort of patients age 1-30.99 years enrolled on frontline COG trials for B-ALL [standard risk (SR): AALL0331; high risk (HR) AALL0232] and T-ALL (AALL0434) that underwent bone marrow assessment of remission at the end of induction therapy (Day 29). Morphologic response was assessed by local centers and was categorized according to traditional criteria: M1 (<5% leukemic blasts - remission) vs. M2 (5-25%) vs. M3 (>25%). MRD was measured by flow cytometry at one of two central laboratories. We determined predictors of MRD discordance and compared event free survival (EFS) between those with discordant vs. concordant morphology/MRD remission assessments.Results: Day 29 remission assessments and central MRD data were available on 9,350 patients, 7,857 (84%) with B-ALL (AALL0331: N=5049; AALL0232: N=2808) and 1,493 (16%) with T-ALL. Table 1 shows the distribution of end induction marrow morphology vs. flow cytometry results. Few patients with M2/M3 marrows had discordant low MRD values. For example, of 84 patients with M3 morphology, only 2 (2.4%) had MRD <5%. Of 202 patients with M2/M3 morphology, 23 (11.4%) had MRD<1% and 9 (4.5%) had MRD<0.1%. Subsequent analyses of discordance were thus restricted to patients with M1 morphology but flow cytometry consistent with failure to achieve remission (MRD>=5%). Using this definition, discordance was uncommon among subjects with B-ALL (66/7,748; 0.9%) but significantly more common in T-ALL (97/1,400; 6.9%; p<0.0001). Among subjects with B-ALL and M1 morphology, significant predictors of discordance (MRD>=5%) in multivariable regression included variables traditionally associated with poor response: age >=10 years [odds ratio (OR)=1.7, 95th percentile confidence interval (CI) 1.1-2.8; p=0.03), presenting white blood cell count >=50,000/microliter (OR=2.1, CI 1.3-3.6; p=0.004), and unfavorable compared to favorable cytogenetics (OR=31, CI 8.9-109; p<0.0001). In B-ALL, subjects with end induction M1 morphology but discordant MRD (>=5%) had modestly superior 5-year EFS when compared to those with M2 morphology and MRD >=5% (33.1%±6.2% vs. 22.0%±6.9%; p=0.03), but EFS was significantly inferior to those with M1 morphology and concordant MRD (<5%) (33.1%±6.2% vs. 86.8%±0.4%; p<0.0001) (Figure 1). In T-ALL, the 5-year EFS of subjects with M1 morphology/discordant MRD was not significantly different from those with M2 morphology and MRD >=5% (80.3%±7.3% vs. 62.7%±13.5%; p=0.13); outcomes of both groups were superior to their equivalents with B-ALL, in keeping with known slower disease clearance kinetics in T-ALL.Conclusions: Patients in morphologically defined remission but with MRD >=5% have outcomes similar to those who fail to achieve morphological remission. These results suggest that, in addition to measuring depth of remission, MRD should replace morphology in defining remission in subjects with ALL, with consequent implications for risk stratification, treatment assignment and eligibility for experimental agents. [Display omitted] [Display omitted] DisclosuresLoh:Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Abbvie: Research Funding. Borowitz:HTG Molecular: Consultancy; Bristol-Myers Squibb: Research Funding; MedImmune: Research Funding; BD Biosciences: Research Funding. Wood:Juno: Other: Laboratory Services Agreement; Pfizer: Honoraria, Other: Laboratory Services Agreement; Amgen: Honoraria, Other: Laboratory Services Agreement; Seattle Genetics: Honoraria, Other: Laboratory Services Agreement.

Early discharge as a mediator of greater ICU-level care requirements in patients not enrolled on the AAML0531 clinical trial: a Children's Oncology Group report.

Previous data suggest that patients enrolled on clinical trials for treatment of cancer have better overall survival than patients who do not enroll; however, short‐term outcomes relative to trial enrollment and corresponding mediators have not been assessed. A cohort of pediatric patients with newly‐diagnosed acute myeloid leukemia was assembled from the Pediatric Health Information System. We evaluated whether patients not enrolled onto Children's Oncology Group trial AAML0531 had greater intensive care unit (ICU)‐level requirements than enrolled patients and whether early discharge after chemotherapy administration mediated this association. Patients not enrolled on AAML0531 were more likely to be discharged early (aOR = 1.40, 95% confidence interval [CI]: 1.02, 1.90) and to require ICU‐level care (aOR = 2.00, 95% CI: 1.06, 3.78) than enrolled patients, but early discharge explained only a small proportion (12.3%) of the absolute difference in ICU‐level care risk. The direct effect of nonenrollment on the need for ICU‐level care was significant (aOR = 1.89, 95% CI: 1.00, 3.94), whereas the indirect effect mediated through early discharge was not (aOR = 1.07, 95% CI: 0.95, 1.19). Factors other than postchemotherapy discharge strategy drive the difference in ICU utilization by trial enrollment status.

A phase III randomized clinical trial (RCT) of tandem myeloablative autologous stem cell transplant (ASCT) using peripheral blood stem cell (PBSC) as consolidation therapy for high-risk neuroblastoma (HR-NB): A Children's Oncology Group (COG) study.

LBA3 Background: ASCT improves event-free survival (EFS) for HR-NB. Pilot studies suggest that intensification of myeloablative therapy using tandem ASCT further improves outcome for HR-NB. We conducted a multicenter RCT comparing tandem vs. single consolidation in patients with HR-NB. Methods: Between 11/2007 and 2/2012, 652 eligible patients (pts) with newly diagnosed HR-NB received induction therapy: 6 cycles of chemotherapy including initial 2 cycles of dose-intensive cyclophosphamide/topotecan followed by PBSC collection. Randomization occurred at end induction to single ASCT with carboplatin-etoposide-melphalan (CEM) or tandem ASCT with thiotepa–cyclophosphamide ASCT followed by a modified CEM (TC:CEM). HR pts with non-MYCN amplified Stage 3 (age&gt;18mos) or Stage 4 (age 12-18 mos) tumors were non-randomly assigned to single ASCT (CEM). EFS and overall survival (OS) were analyzed as intent-to-treat. Results: Median age at study entry was 3.1 yrs, 88% (n=574 pts) had Stage 4 disease and 38.2% (n=249 tumors) had MYCN amplification. A total of 355 pts were randomized (CEM n=179 pts; TC:CEM n=176 pts) and 27 patients were non-randomly assigned to CEM. Of randomized pts, 249 patients received post-consolidation immunotherapy on COG trials. Treatment-related mortality was 2.6% (Induction n=7 [1%]; Consolidation n=10 [2.8%; n=8 CEM, n=2 TC:CEM]). Rates of severe mucosal, infectious or liver toxicities were similar between arms. 3-year EFS and OS from diagnosis were 51.1±2.0% and 68.2±1.9%, respectively. EFS and OS for randomized cohort are shown in the Table. Conclusions: Tandem myeloablative consolidation therapy improves survival probability in patients with high-risk neuroblastoma, especially in the setting in post-consolidative immunotherapy. Clinical trial information: NCT00567567. [Table: see text]

A Comparative Evaluation of Normal Tissue Doses for Patients Receiving Radiation Therapy for Hodgkin Lymphoma on the Childhood Cancer Survivor Study and Recent Children's Oncology Group Trials

Survivors of pediatric Hodgkin lymphoma (HL) are recognized to have an increased risk of delayed adverse health outcomes related to radiation therapy (RT). However, the necessary latency required to observe these late effects means that the estimated risks apply to outdated treatments. We sought to compare the normal tissue dose received by children treated for HL and enrolled in the Childhood Cancer Survivor Study (CCSS) (diagnosed 1970-1986) with that of patients treated in recent Children's Oncology Group (COG) trials (enrolled 2002-2012). RT planning data were obtained for 50 HL survivors randomly sampled from the CCSS cohort and applied to computed tomography planning data sets to reconstruct the normal tissue dosimetry. For comparison, the normal tissue dosimetry data were obtained for all 191 patients with full computed tomography-based volumetric RT planning on COG protocols AHOD0031 and AHOD0831. For early-stage patients, the mean female breast dose in the COG patients was on average 83.5% lower than that for CCSS patients, with an absolute reduction of 15.5Gy. For advanced-stage patients, the mean breast dose was decreased on average by 70% (11.6 Gy average absolute dose reduction). The mean heart dose decreased on average by 22.9Gy (68.6%) and 17.6Gy (56.8%) for early- and advanced-stage patients, respectively. All dose comparisons for breast, heart, lung, and thyroid were significantly lower for patients in the COG trials than for the CCSS participants. Reductions in the prescribed dose were a major contributor to these dose reductions. These are the first data quantifying the significant reduction in the normal tissue dose using actual, rather than hypothetical, treatment plans for children with HL. These findings provide useful information when counseling families regarding the risks of contemporary RT.