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Background: Prior studies have identified that survivors of childhood acute lymphoblastic leukemia (ALL) report poor health status. It is unknown how risk-stratified therapy impacts the health status of ALL survivors. Methods: We estimated and compared the prevalence of self-reported poor health status among adult (≥18 years) survivors of childhood ALL diagnosed at age Results: Among 5,119 survivors and 4,693 siblings, survivors were more likely to report poor health status in each domain including poor general health (13.5% vs. 7.4%; PR = 1.92; 95% CI, 1.69–2.19). Compared with 70s, 90sSR and 90sHR were less likely to report poor general health (90sSR: PR = 0.75; 95% CI, 0.57–0.98; 90sHR: PR = 0.58; 95% CI, 0.39–0.87), functional impairment (90sSR: PR = 0.56; 95% CI, 0.42–0.76; 90sHR: PR = 0.63; 95% CI, 0.42–0.95), and activity limitations (90sSR: 0.61; 95% CI, 0.45–0.83; 90sHR: PR = 0.59; 95% CI, 0.38–0.91). An added adjustment for chronic conditions in multivariable models partially attenuated 90sSR risk estimates. Conclusions: Risk-stratified ALL therapy has succeeded in reducing risk for poor general health, functional impairment, and activity limitations among more recent survivors of standard- and high-risk therapy. Impact: Future research into the relationship between risk-stratified therapy, health status, and late health outcomes may provide new opportunities to further improve late morbidity among survivors.

Key Points Orthopedic toxicity was common in adolescent and young adult patients treated on DFCI Consortium ALL pediatric protocols.Younger age and exposure to pegaspargase were associated with higher risk of ON, and patients with ON had superior OS., Visual Abstract, Adolescent and young adult patients with acute lymphoblastic leukemia (ALL) have superior outcomes when treated on pediatric regimens. Pediatric ALL regimens rely heavily on corticosteroids and asparaginase and are known to increase the risk of osteonecrosis (ON) and fractures in children, particularly adolescents. Orthopedic toxicity among young adults treated on pediatric-inspired regimens is not well described. Here, we report the symptomatic orthopedic toxicities of patients aged 15 to 50 years treated on sequential Dana-Farber Cancer Institute ALL Consortium protocols. Among 367 patients with a median age of 23 years (range, 15-50 years; 68% aged

Hispanic children have a higher incidence of acute lymphoblastic leukemia (ALL) and inferior treatment outcomes relative to non-Hispanic White children. We previously reported that Hispanic children with ALL had lower risk of fracture and osteonecrosis. To unravel the genetic root of such ethnic differences, we genotyped 449 patients from the DFCI 05-001 cohort and analyzed their ancestry. Patients with discordant clinical and genetic ancestral groups were reclassified, and those with unknown ancestry were reassigned on the basis of genetic estimates. Both clinical and genetic ancestries were analyzed in relation to risk of bone toxicities and survival outcomes. Consistent with clinically reported race/ethnicity, genetically defined Hispanic and Black patients had significantly lower risk of fracture (Hispanic: subdistribution hazard ratio [SHR], 0.42; 95% confidence interval [CI], 0.22-0.81; P = .01; Black: SHR, 0.28; 95% CI, 0.10-0.75; P = .01), and osteonecrosis (Hispanic: SHR, 0.12; 95% CI, 0.02-0.93; P = .04; Black: SHR, 0.24; 95% CI, 0.08-0.78; P = .02). The lower risk was driven by African but not Native American or Asian ancestry. In addition, patients with a higher percentage of Native American ancestry had significantly poorer overall survival and event-free survival. Our study revealed that the lower risk of bone toxicities among Black and Hispanic children treated for ALL was attributed, in part, to the percentage of African ancestry in their genetic admixture. The findings provide suggestive evidence for the protective effects of genetic factors associated with African decent against bone damage caused by ALL treatment and clues for future studies to identify underlying biological mechanisms.

PURPOSE The benefits and risks of supplementation with antioxidants during cancer therapy have been a controversial area. Few studies have systematically evaluated dietary intake of antioxidants with toxicity and survival in childhood cancer. We sought to determine the role of dietary intake of antioxidants on rates of infections, mucositis, relapse, and disease-free survival during induction and postinduction phases of therapy among children and adolescents with acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS We enrolled 794 children in a prospective clinical trial for treatment of ALL. Dietary intake was prospectively evaluated by a food frequency questionnaire. The association between dietary intake of antioxidants and treatment-related toxicities and survival were evaluated with the Benjamini-Hochberg false discovery rate (q) and logistic regression and the Kaplan-Meier method, respectively. RESULTS Dietary surveys were available for analysis from 614 (77%), and 561 (71%) participants at diagnosis and at end of induction, respectively. Of 513 participants who completed the dietary surveys at both time points, 120 (23%) and 87 (16%) experienced a bacterial infection and 22 (4%) and 55 (10%) experienced mucositis during the induction or postinduction phases of treatment, respectively. Increased intake of dietary antioxidants was associated with significantly lower rates of infection and mucositis. No association with relapse or disease-free survival was observed. Supplementation was not associated with toxicity, relapse, or survival. CONCLUSION Consumption of antioxidants through dietary intake was associated with reduced rates of infection or mucositis, with no increased risk of relapse or reduced survival. Dietary counseling on a well-balanced diet that includes an array of antioxidants from food sources alone may confer a benefit from infections and mucositis during treatment of childhood ALL.

Background The outcome of infants with KMT2A-germline ALL is much better than of infants with KMT2A-rearranged ALL, but still worse than of non-infant ALL patients. Here, we describe the outcome and prognostic factors for infants with KMT2A-germline ALL treated on Interfant-06 protocol. Methods 167 infants with KMT2A-germline ALL were enrolled in Interfant-06. Univariate analysis on prognostic factors (age, WBC at diagnosis, prednisolone response and CD10 expression) was performed on KMT2A-germline infants in complete remission at the end of induction (EOI) (n=163). Bone marrow minimal residual disease (MRD) was measured in 73 patients, by real-time quantitative PCR of immunoglobulin genes and/or T-cell receptor genes, at various time points (EOI, n= 68, end of consolidation (EOC) n= 56, and before OCTADAD (n=57)). MRD results were classified as negative, intermediate (< 5*10 -4), and high (≥5*10 -4). Genetic data on NUTM1 rearrangements and MRD were available in 53 patients. Results The 6-year event free survival [SE] and overall survival [ SE] was 73.9% (3,6) and 87.2% (2.7). 28 of 31 (90%) relapses occurred early, within 2 years of diagnosis. Treatment related mortality was 3.6%. Age 6 months of age (p=0.04). Of the MRD timepoints, MRD at end of induction (EOI) was most prognostic for outcome. At EOI, 76.5% (n=52/68) of patients were either MRD negative (41.2%, n=28) or intermediate MRD (35.3%, n=24). 23.5% (n=16) had high EOI MRD, which was associated with significantly lower 6-year DFS (SE), compared to patients with intermediate or negative EOI MRD (61.4% (12.4), 76.4% (11.3) and 87.9% (6.6), respectively; p=0.02, Figure 1a). At EOC, 55.4% (n=31/56) of patients were MRD negative. Outcome by MRD levels at EOC was not significantly different (p=0.24); the 6-year DFS (SE) of negative and intermediate EOC MRD patients was 89.0% (6.0) and 72.7 % (10.6), respectively, while only one of the 5 patients with high EOC MRD relapsed in BM and CNS (Figure 1b). MRD data for both EOI and EOC were available for 55 patients. Of these patients, 18 were MRD negative at EOI and EOC, with a 6-year DFS 93.3% (SE, 6.4). Five patients had negative EOI MRD, but showed intermediate EOC MRD levels; none of these patients relapsed. There were 12 of 55 patients who were MRD positive at EOI and became MRD negative at EOC. These patients had a 6-year DFS of 82.5 % (SE, 11.3). Patients with detectable disease at both timepoints had a 6-year DFS of 68.3% (SE,10.8) (n=20, Figure 1c). At the end of MARMA (TP5), 77.2% (n=44/57) of patients were MRD negative. MRD at TP5 was significantly related to DFS (Figure 1d); the 6-year DFS was 89.6% (SE, 5.0) for MRD negative patients, compared to 65.6% (SE, 14.0) for patients with intermediate MRD levels (p= 0.039). In the current study, NUTM1 status was known in 53 patients with MRD data. Of them, 13 harbored a NUTM1-rearrangement. Seven out of 11 (63.6%) were aged< 6 months and 6 out of 42 (14.3%) were older. None of them relapsed, despite positive EOI MRD detected in 8 cases. Conclusion We conclude that young age at diagnosis and low EOI MRD are favorable prognostic factors in infants with KMT2A-germline ALL. However, the prognostic value of MRD is not as strong as in infants with KMT2A-rearranged ALL or older children with ALL. This can partly be explained by the differences in genetic makeup of infants with KMT2A-germline ALL, thus supporting the hypothesis that in the future a combined MRD- and genetic-based stratification of KMT2A-g infants might be considered Figure 1 Figure 1. Disclosures Biondi: Colmmune: Honoraria; Bluebird: Other: Advisory Board; Novartis: Honoraria; Incyte: Consultancy, Other: Advisory Board; Amgen: Honoraria. Locatelli: Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Miltenyi: Speakers Bureau; Medac: Speakers Bureau; Jazz Pharamceutical: Speakers Bureau; Takeda: Speakers Bureau. Silverman: Takeda, Servier, Syndax, Jazz Pharmaceuticals: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Schrappe: Novartis: Honoraria, Other: research support; SigmaTau: Other: research support; Amgen: Other: research support; Servier: Honoraria; Novartis: Honoraria; JazzPharma: Honoraria; JazzPharma: Honoraria, Other: research support; SHIRE: Other: research support; Servier: Honoraria, Other: research support.

Comparison of treatment strategies in de novo pediatric acute lymphoblastic leukemia (ALL) requires standardized measures of efficacy. Key parameters that define disease-related events, including complete remission (CR), treatment failure (TF; not achieving CR), and relapse (loss of CR) require an updated consensus incorporating modern diagnostics. We collected the definitions of CR, TF, and relapse from recent and current pediatric clinical trials for the treatment of ALL, including the key components of response evaluation (timing, anatomic sites, detection methods, and thresholds) and found significant heterogeneity, most notably in the definition of TF. Representatives of the major international ALL clinical trial groups convened to establish consensus definitions. CR should be defined at a time point no earlier than at the end of induction and should include the reduction of blasts below a specific threshold in bone marrow and extramedullary sites, incorporating minimal residual disease (MRD) techniques for marrow evaluations. TF should be defined as failure to achieve CR by a prespecified time point in therapy. Relapse can only be defined in patients who have achieved CR and must include a specific threshold of leukemic cells in the bone marrow confirmed by MRD, the detection of central nervous system leukemia, or documentation of extramedullary disease. Definitions of TF and relapse should harmonize with eligibility criteria for clinical trials in relapsed/refractory ALL. These consensus definitions will enhance the ability to compare outcomes across pediatric ALL trials and facilitate development of future international collaborative trials.

Chimeric antigen receptor (CAR) T cells have demonstrated clinical benefit in patients with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). We undertook a multicenter clinical trial to determine toxicity, feasibility, and response for this therapy. A total of 25 pediatric/young adult patients (age, 1-22.5 years) with R/R B-ALL were treated with 19-28z CAR T cells. Conditioning chemotherapy included high-dose (3 g/m2) cyclophosphamide (HD-Cy) for 17 patients and low-dose (≤1.5 g/m2) cyclophosphamide (LD-Cy) for 8 patients. Fifteen patients had pretreatment minimal residual disease (MRD

Objectives Acute pancreatitis is a significant toxicity of L-asparaginase, a chemotherapeutic agent used to treat acute lymphoblastic leukemia. This case series describes the short-term clinical course and disposition of patients who developed asparaginase-associated pancreatitis (AAP) at one quaternary pediatric center. Methods Clinical data, including laboratory data, inpatient and intensive care unit (ICU) days, imaging findings, presence of complications such as need for ventilation, dialysis, and the development of pleural effusions, and mode of nutrition were abstracted from the medical record of patients with AAP. Pediatric criteria were used to classify episode severity based on the development of organ failure and local complications, such as pancreatic necrosis. Results Between 2005 and 2015, 34 patients had AAP with 43 distinct episodes of pancreatitis. The median inpatient length of stay was 10 days (range 2 to 65). Seven episodes (16.3%) required ICU-level care. Seventeen episodes (39.5%) were severe based on the development of organ failure or presence of pancreatic necrosis. Total parenteral nutrition (TPN) was used in 17 episodes (39.5%); for 34 episodes (79.1%), patients were discharged on entirely oral feeds. Antibiotics were administered in 20 episodes (46.5%). Pancreatic necrosis was identified within the first week in 12 episodes (27.9%). There were no deaths due to AAP. Conclusions The clinical course varies widely among patients with AAP. Over 1/3 of the patients in this series developed severe pancreatitis. Although the prognosis of AAP is generally good, many patients develop systemic complications of AAP, requiring TPN or ICU-level care. An infographic is available for this article at:http://links.lww.com/MPG/C5554.

PURPOSE Dana-Farber Cancer Institute Acute Lymphoblastic Leukemia (ALL) Consortium Protocol 11-001 assessed efficacy and toxicity of calaspargase pegol (calaspargase), a novel pegylated asparaginase formulation with longer half-life, compared with the standard formulation pegaspargase. METHODS Patients age 1 to ≤ 21 years with newly diagnosed ALL or lymphoblastic lymphoma were randomly assigned to intravenous pegaspargase or calaspargase, 2,500 IU/m2/dose. Patients received one induction dose. Beginning week 7, pegaspargase was administered every 2 week for 15 doses and calaspargase every 3 week for 10 doses (30 weeks). Serum asparaginase activity (SAA) (≥ 0.1 IU/mL considered therapeutic) was assessed 4, 11, 18, and 25 days after the induction dose and before each postinduction dose. RESULTS Between 2012 and 2015, 239 eligible patients enrolled (230 ALL, nine lymphoblastic lymphoma); 120 were assigned to pegaspargase and 119 to calaspargase. After the induction dose, SAA was ≥ 0.1 IU/mL in ≥ 95% of patients on both arms 18 days after dosing. At day 25, more patients had SAA ≥ 0.1 IU/mL with calaspargase (88% v 17%; P ˂ .001). Postinduction, median nadir SAAs were similar (≥ 1.0 IU/mL) for both arms. Of 230 evaluable patients, 99% of pegaspargase and 95% of calaspargase patients achieved complete remission ( P = .12), with no difference in frequency of high end-induction minimal residual disease among evaluable patients with B acute lymphoblastic leukemia (B-ALL). There were no differences in frequencies of asparaginase allergy, pancreatitis, thrombosis, or hyperbilirubinemia. With 5.3 years median follow-up, 5-year event-free survival for pegaspargase was 84.9% (SE ± 3.4%) and 88.1% (± SE 3.0%) for calaspargase ( P = .65). CONCLUSION Every 3-week calaspargase had similar nadir SAA, toxicity, and survival outcomes compared with every 2-week pegaspargase. The high nadir SAA observed for both preparations suggest dosing strategies can be further optimized.

Acute lymphoblastic leukemia (ALL) is among the most common cancers in children. With improvements in combination chemotherapy regimens, the overall survival has increased to over 90%. However, the current challenge is to mitigate adverse events resulting from the complex therapy. Several chemotherapies intercept cancer metabolism, but little is known about their collective role in altering host metabolism. We profiled the metabolomic changes in plasma of ALL patients initial- and post- induction therapy. We exploited a biorepository of non-fasted plasma samples derived from the Dana Farber Cancer Institute ALL Consortium; these samples were obtained from 50 ALL patients initial- and post-induction therapy. Plasma metabolites and complex lipids were analyzed by high resolution tandem mass spectrometry and differential mobility tandem mass spectrometry. Data were analyzed using a covariate-adjusted regression model with multiplicity adjustment. Pathway enrichment analysis and co-expression network analysis were performed to identify unique clusters of molecules. More than 1200 metabolites and complex lipids were identified in the total of global metabolomics and lipidomics platforms. Over 20% of those molecules were significantly altered. In the pathway enrichment analysis, lipids, particularly phosphatidylethanolamines (PEs), were identified. Network analysis indicated that the bioactive fatty acids, docosahexaenoic acid (DHA)-containing (22:6) triacylglycerols (TAGs), were decreased in the post-induction therapy. Metabolomic profiling in ALL patients revealed a large number of alterations following induction chemotherapy. In particular, lipid metabolism was substantially altered. The changes in metabolites and complex lipids following induction therapy could provide insight into the adverse events experienced by ALL patients.

Despite a remarkable increase in the genomic profiling of cancer, integration of genomic discoveries into clinical care has lagged behind. We report the feasibility of rapid identification of targetable mutations in 153 pediatric patients with relapsed/refractory or high-risk leukemias enrolled on a prospective clinical trial conducted by the LEAP Consortium. Eighteen percent of patients had a high confidence Tier 1 or 2 recommendation. We describe clinical responses in the 14% of patients with relapsed/refractory leukemia who received the matched targeted therapy. Further, in order to inform future targeted therapy for patients, we validated variants of uncertain significance, performed ex vivo drug-sensitivity testing in patient leukemia samples, and identified new combinations of targeted therapies in cell lines and patient-derived xenograft models. These data and our collaborative approach should inform the design of future precision medicine trials. Significance: Patients with relapsed/refractory leukemias face limited treatment options. Systematic integration of precision medicine efforts can inform therapy. We report the feasibility of identifying targetable mutations in children with leukemia and describe correlative biology studies validating therapeutic hypotheses and novel mutations. See related commentary by Bornhauser and Bourquin, p. 1322. This article is highlighted in the In This Issue feature, p. 1307

Aim: To evaluate top-ranking genes identified through genome-wide association studies for an association with corticosteroid-related osteonecrosis in children with acute lymphoblastic leukemia (ALL) who received Dana–Farber Cancer Institute treatment protocols. Patients & methods: Lead SNPs from these studies, as well as other variants in the same genes, pooled from whole exome sequencing data, were analyzed for an association with osteonecrosis in childhood ALL patients from Quebec cohort. Top-ranking variants were verified in the replication patient group. Results: The analyses of variants in the ACP1-SH3YL1 locus derived from whole exome sequencing data showed an association of several correlated SNPs (rs11553746, rs2290911, rs7595075, rs2306060 and rs79716074). The rs79716074 defines *B haplotype of the APC1 gene, which is well known for its functional role. Conclusion: This study confirms implication of the ACP1 gene in the treatment-related osteonecrosis in childhood ALL and identifies novel, potentially causal variant of this complication.

Asparaginase-associated pancreatitis is a life-threatening toxicity to childhood acute lymphoblastic leukemia treatment. To elucidate genetic predisposition and asparaginase-associated pancreatitis pathogenesis, ten trial groups contributed remission samples from patients aged 1.0−17.9 years treated for acute lymphoblastic leukemia between 2000 and 2016. Cases (n=244) were defined by the presence of at least two of the following criteria: (i) abdominal pain; (ii) levels of pancreatic enzymes ≥3 x upper normal limit; and (iii) imaging compatible with pancreatitis. Controls (n=1320) completed intended asparaginase therapy, with 78% receiving ≥8 injections of pegylated-asparaginase, without developing asparaginase-associated pancreatitis. rs62228256 on 20q13.2 showed the strongest association with the development of asparaginase-associated pancreatitis (odds ratio=3.75; P=5.2x10 -8 ). Moreover, rs13228878 (OR=0.61; P=7.1x10 -6 ) and rs10273639 (OR=0.62; P=1.1x10 -5 ) on 7q34 showed significant association with the risk of asparaginase-associated pancreatitis. A Dana Farber Cancer Institute ALL Consortium cohort consisting of patients treated on protocols between 1987 and 2004 (controls=285, cases=33), and the Children’s Oncology Group AALL0232 cohort (controls=2653, cases=76) were available as replication cohorts for the 20q13.2 and 7q34 variants, respectively. While rs62228256 was not validated as a risk factor (P=0.77), both rs13228878 (P=0.03) and rs10273639 (P=0.04) were. rs13228878 and rs10273639 are in high linkage disequilibrium (r 2 =0.94) and associated with elevated expression of the PRSS1 gene, which encodes for trypsinogen, and are known risk variants for alcohol-associated and sporadic pancreatitis in adults. Intra-pancreatic trypsinogen cleavage to proteolytic trypsin induces autodigestion and pancreatitis. In conclusion, this study finds a shared genetic predisposition between asparaginase-associated pancreatitis and non-asparaginase-associated pancreatitis, and targeting the trypsinogen activation pathway may enable identification of effective interventions for asparaginase-associated pancreatitis.

Context: Ph+ ALL is associated with improved outcomes when tyrosine kinase inhibitors (TKIs) are added to chemotherapy, with 5-year event-free survival (EFS) and overall survival (OS) for newly diagnosed patients of 60% and 86%, respectively. Ponatinib is a third-generation TKI active against BCR-ABL1 and all identified single-mutation variants and is the only TKI active against the T315I mutation. Ponatinib has approvals for adults with chronic-/accelerated-/blast-phase chronic myeloid leukemia, Ph+ ALL resistant/intolerant to other TKIs, or have the T315I mutation. Objective: Determine the recommended phase 2 dose (RP2D) and assess pharmacokinetics, safety, and efficacy of ponatinib in combination with chemotherapy in pediatric patients with relapsed or resistant Ph+ ALL or with the T315I mutation. Methods: This phase 1/2, single-arm, open-label, multicenter study will enroll patients into phase 1 with a rolling 6 design; the first cohort will include up to 12 patients (≥30 kg and able to swallow tablets) for dose confirmation. Another cohort of 6 patients will enroll to assess the age-appropriate mini-tablet formulation (AAF) at the RP2D. Phase 2 will enroll ≈68 patients, including those in phase 1, at the RP2D. Patients (aged ≥1–21 years) with Ph+ ALL, Ph+ mixed phenotype acute leukemia, or Ph-like ALL (US only) with targetable ABL-class kinase-activating lesions must have relapsed or be resistant/intolerant to ≥1 prior therapy with a BCR-ABL1-targeted or ABL-class TKI or have a BCR-ABL1 T315I mutation. In phase 1, the primary endpoint is the RP2D of ponatinib with chemotherapy. Secondary endpoints are complete response (CR) rate at the end of the reinduction block and characterization of BCR-ABL1 domain mutations before and after ponatinib treatment. In phase 2, the primary endpoint is CR rate at the end of the reinduction block. Secondary endpoints include the proportion of patients in continued CR or who achieve CR at the end of consolidation, proportion with minimal residual disease-negative status

Poor adherence to 6-mercaptopurine during acute lymphoblastic leukemia (ALL) therapy increases relapse risk. Clinically-significant non-adherence has been documented in up to 30% of children treated for ALL on Children’s Oncology Group trials. Whether non-adherence rates vary across regimens with different chemotherapy schedules and modes of administration is not known. In a cross-sectional survey study of N= 61 children treated on, or as per Dana-Farber Cancer Institute (DFCI) ALL Consortium Protocol 11-001, 25% (95% CI 14 – 37%) of respondents self-reported non-adherence to 6MP, suggesting that the frequency of non-adherence may be similar across different Consortia regimens.

PURPOSE Risk-stratified therapy, which modifies treatment on the basis of clinical and biologic features, has improved 5-year overall survival of childhood acute lymphoblastic leukemia (ALL) to 90%, but its impact on long-term toxicity remains unknown. METHODS We assessed all-cause and health-related late mortality (including late effects of cancer therapy), subsequent malignant neoplasms (SMNs), chronic health conditions, and neurocognitive outcomes among 6,148 survivors of childhood ALL (median age, 27.9 years; range, 5.9-61.9 years) diagnosed between 1970 and 1999. Therapy combinations and treatment intensity defined 6 groups: 1970s-like (70s), standard- or high-risk 1980s-like (80sSR, 80sHR) and 1990s-like (90sSR, 90sHR), and relapse/transplantation (R/BMT). Cumulative incidence, standardized mortality ratios, and standardized incidence ratios were compared between treatment groups and with the US population. RESULTS Overall, 20-year all-cause late mortality was 6.6% (95% CI, 6.0 to 7.1). Compared with 70s, 90sSR and 90sHR experienced lower health-related late mortality (rate ratio [95% CI]: 90sSR, 0.2 [0.1 to 0.4]; 90sHR, 0.3 [0.1 to 0.7]), comparable to the US population (standardized mortality ratio [95% CI]: 90sSR, 1.3 [0.8 to 2.0]; 90sHR, 1.7 [0.7 to 3.5]). Compared with 70s, 90sSR had a lower rate of SMN (rate ratio [95% CI], 0.3 [0.1 to 0.6]) that was not different from that of the US population (standardized incidence ratio [95% CI], 1.0 [0.6 to 1.6]). The 90sSR group had fewer severe chronic health conditions than the 70s (20-year cumulative incidence [95% CI], 11.0% [9.7% to 12.3%] v 22.5% [19.4% to 25.5%]) and a lower prevalence of impaired memory (prevalence ratio [95% CI], 0.7 [0.6 to 0.9]) and task efficiency (0.5 [0.4 to 0.7]). CONCLUSION Risk-stratified therapy has reduced late morbidity and mortality among contemporary survivors of standard-risk ALL, represented by 90sSR. Health-related late mortality and SMN risks among 5-year survivors of contemporary, standard-risk childhood ALL are comparable to the general population.

BACKGROUND/OBJECTIVES While outcomes for pediatric T-cell acute lymphoblastic leukemia (T-ALL) are favorable, there are few widely accepted prognostic factors, limiting the ability to risk stratify therapy. DESIGN/METHODS Dana-Farber Cancer Institute (DFCI) Protocols 05-001 and 11-001 enrolled pediatric patients with newly diagnosed B- or T-ALL from 2005 to 2011 and from 2012 to 2015, respectively. Protocol therapy was nearly identical for patients with T-ALL (N = 123), who were all initially assigned to the high-risk arm. End-induction minimal residual disease (MRD) was assessed by reverse transcription polymerase chain reaction (RT-PCR) or next-generation sequencing (NGS), but was not used to modify postinduction therapy. Early T-cell precursor (ETP) status was determined by flow cytometry. Cases with sufficient diagnostic DNA were retrospectively evaluated by targeted NGS of known genetic drivers of T-ALL, including Notch, PI3K, and Ras pathway genes. RESULTS The 5-year event-free survival (EFS) and overall survival (OS) for patients with T-ALL was 81% (95% CI, 73-87%) and 90% (95% CI, 83-94%), respectively. ETP phenotype was associated with failure to achieve complete remission, but not with inferior OS. Low end-induction MRD (

Aim: To evaluate the association between human leukocyte antigen (HLA) alleles and native Escherichia coli asparaginase hypersensitivity (AH) in children with acute lymphoblastic leukemia (ALL) who received Dana-Farber Cancer Institute treatment protocols. Patients & methods: HLA-DQA1, HLA-DRB1 and HLA-DQB1 alleles were retrieved from available whole exome sequencing data of a subset of childhood ALL patients from Quebec ALL cohort and analyzed for an association with AH. PCR assay was developed to analyze associated alleles in the entire discovery and replication cohorts. Results: Two alleles in linkage disequilibrium ( HLA-DRB1*07:01 and DQA1*02:01) were associated with AH. Additional analyses, performed to distinguish between HLA-DRB1*07:01 haplotypes with and without DQB1*02:02 allele, showed that the association was dependent on the presence of DQB1*02:02. Conclusion: This study confirms the implication of HLA-DRB1*07:01, DQA1*02:01 and DQB1*02:02 alleles in developing AH in childhood ALL.

Key Points We report a patient with hepatosplenic T-cell lymphoma (HSTL) and compare the disease to the derived xenograft model. Enhancer of zeste homolog 2 (EZH2) inhibitor treatment of an EZH2-mutant HSTL patient-derived xenograft model led to prolonged survival.

Treatment for children with Philadelphia chromosome-positive acute lymphoblastic leukemia has changed radically over the past 20 years. This type of leukemia used to have dismal prognosis, but today cure rates have improved with combination of cytotoxic chemotherapy and a tyrosine kinase inhibitor such as imatinib or dasatinib, with hematopoietic stem cell transplant reserved for patients who are at high risk based on slow response to therapy or who relapse. Treating these patients can be challenging particularly if they are not enrolled on a clinical trial. Here, we describe our approach to these patients.

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Advancements in technology that enhance our understanding of the biology of the disease, risk-adapted therapy, and enhanced supportive care have contributed to improved survival rates. However, additional clinical management is needed to improve outcomes for patients classified as high risk at presentation (eg, T-ALL, infant ALL) and who experience relapse. The NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for pediatric ALL provide recommendations on the workup, diagnostic evaluation, and treatment of the disease, including guidance on supportive care, hematopoietic stem cell transplantation, and pharmacogenomics. This portion of the NCCN Guidelines focuses on the frontline and relapsed/refractory management of pediatric ALL.

Insufficient exposure to asparaginase therapy is a barrier to optimal treatment and survival in childhood acute lymphoblastic leukaemia (ALL). Three important reasons for inactivity or discontinuation of asparaginase therapy are infusion related reactions (IRRs), pancreatitis and life-threatening central nervous system (CNS). For IRRs, real-time therapeutic drug monitoring (TDM) and premedication are important aspects to be considered. For pancreatitis and CNS thrombosis one key question is if patients should be re-exposed to asparaginase after their occurrence.An expert panel met during the Congress of the International Society for Paediatric Oncology in Lyon in October 2019 to discuss strategies for diminishing the impact of these three toxicities. The panel agreed that TDM is particularly useful for optimising asparaginase treatment and that when a tight pharmacological monitoring programme is established premedication could be implemented more broadly to minimise the risk of IRR. Re-exposure to asparaginase needs to be balanced against the anticipated risk of leukemic relapse. However, more prospective data are needed to give clear recommendations if to re-expose patients to asparaginase after the occurrence of severe pancreatitis and CNS thrombosis.

Health-related quality of life (HRQL) improved progressively during therapy and beyond in children treated for acute lymphoblastic leukemia on the Dana-Farber Cancer Institute (DFCI) 95-01 protocol. This study aimed to validate that trajectory in a successor study (DFCI 00-01) and to compare the HRQL of patients in the 2 studies. Children aged above 5 years were assessed during each phase of treatment (N=4) and 2 years after completion of therapy. Health status and HRQL were measured using Health Utilities Index (HUI) instruments, HUI2 and HUI3. Quality-adjusted life years (QALYs) were calculated and compared with the general population, and patients treated on DFCI 95-01. Over 5 intervals and 758 HUI assessments, mean HRQL increased progressively from remission induction to the time after treatment (P

Dana-Farber Cancer Institute (DFCI) ALL Consortium Protocol 05-001 tested a new risk stratification system in children and adolescents with newly diagnosed acute lymphoblastic leukemia (ALL). At study entry, B-ALL patients were classified as standard risk (SR) or high risk (HR) based on age, white blood cell (WBC) count, and central nervous system status. After achieving complete remission (CR), patients with high end-induction minimal residual disease (MRD) (≥10−3 by polymerase chain reaction analysis of patient-specific antigen receptor rearrangements) and/or adverse cytogenetics (KMT2A rearrangement or hypodiploidy) were reclassified as very high risk (VHR) and received intensified therapy. IKZF1 deletion status was retrospectively evaluated by multiplex ligation-dependent probe amplification. Between 2005 and 2011, 678 Philadelphia chromosome-negative B-ALL patients aged 1 to 18 years enrolled; 651 achieved CR and 648 received a final risk group. Among all 678 patients, 5-year event-free survival (EFS) was 87% (95% confidence interval [CI], 84-89) and overall survival 93% (95% CI, 90-94). Five-year disease-free survival of SR patients (N = 407) was 94% (95% CI, 91-96), HR (N = 176) was 84% (95% CI, 77-88), and VHR (N = 65) was 79% (95% CI, 67-87). IKZF1 deletion was present in 62 of 385 (16%) assessed patients and was associated with inferior 5-year EFS (63%; 95% CI, 49%-74% vs 88%; 95% CI, 84%-91%; P < .001), and higher 5-year cumulative incidence of relapse, including among those with low MRD (24% vs 8%, P = .001). In multivariable analysis, age ≥15 years, WBC ≥50 × 109/L, IKZF1 deletion, and MRD ≥10−4 was each associated with inferior outcome. In conclusion, risk-stratified therapy on DFCI 05-001 resulted in favorable outcomes for B-ALL patients, including those with VHR features. IKZF1 deletion was an independent predictor of inferior outcome. This trial was registered at www.clinicaltrials.gov as #{"type":"clinical-trial","attrs":{"text":"NCT00400946","term_id":"NCT00400946"}}NCT00400946.

Recurrent chromosomal rearrangements carry prognostic significance in pediatric B-lineage acute lymphoblastic leukemia (B-ALL). Recent genome-wide analyses identified a high-risk B-ALL subtype characterized by a diverse spectrum of genetic alterations activating kinases and cytokine receptor genes. This subtype is associated with a poor prognosis when treated with conventional chemotherapy but has demonstrated sensitivity to the relevant tyrosine kinase inhibitors. We sought to determine the frequency of kinase-activating fusions among National Cancer Institute (NCI) high-risk, Ph-negative, B-ALL patients enrolled on Dana-Farber Cancer Institute ALL Consortium Protocol 05-001 and to describe their associated clinical characteristics and outcomes. Among the 105 patients screened, 16 (15%) harbored an ABL-class fusion (ETV6-ABL1: n = 1; FOXP1-ABL1: n = 1; SFPQ-ABL1: n = 1; ZC3HAV1-ABL2: n = 1) or a fusion activating the JAK-STAT pathway (P2RY8-CRLF2: n = 8; PAX5-JAK2: n = 4). Sixty-nine percent of patients with an identified fusion had a concomitant IKZF1 deletion (n = 11). In univariate analysis, fusion-positivity and IKZF1 deletion were each associated with inferior event-free survival; IKZF1 deletion retained statistical significance in multivariable analysis (hazard ratio, 2.64; P = .019). Our findings support therapy intensification for IKZF1-altered patients, irrespective of the presence of a kinase-activating fusion.

Osteonecrosis (ON) is corticosteroid-related complication, reported in children with acute lymphoblastic leukemia (ALL). We have previously found that polymorphisms in BCL2L11 gene coding for pro-apoptotic Bim protein influence reduction of overall survival (OS) in a corticosteroid (CS) dose-dependent manner in childhood ALL patients. The same set of SNPs was here investigated for an association with CS-related ON assessed retrospectively in 304 children with ALL from Quebec (QcALL cohort) who received Dana-Farber Cancer Institute (DFCI) ALL treatment protocols. Two-year cumulative incidence of symptomatic ON was 10.6%. Two BCL2L11 polymorphisms, the 891T>G (rs2241843) in all QcALL patients and 29201C>T (rs724710) in high-risk group were significantly associated with ON, P = 0.009 and P = 0.003, respectively. The association remained significant in multivariate model (HR891TT = 2.4, 95% CI 1.2–4.8, P = 0.01 and HR29201CC = 5.7, 95% CI 1.6–20.9, P = 0.008). Both polymorphisms influenced viability of dexamethasone treated lymphoblastoid cell lines (P ≤ 0.03). The 891T>G influenced Bim gamma isoform levels (0.03) and its association with ON was also confirmed in replication DFCI cohort (N = 168, P = 0.03). QcALL children had a high incidence of ON during therapy, which was highly associated with BCL2L11 polymorphisms.

Background: Inotuzumab ozogamicin (INO) is a humanized, anti-CD22 antibody conjugated to calicheamicin with FDA approval for treatment of adults with relapsed or refractory (r/r) B-acute lymphoblastic leukemia (B-ALL). While it is associated with favorable complete remission rates in r/r B-ALL patients (pts), hepatotoxicity both during treatment and with subsequent hematopoietic cell transplantation (HCT) remains a challenge. In general, venoocclusive disease (VOD) during HCT in pediatric pts is estimated at 10-20%. Following treatment with INO, however, up to 52% of pts undergoing HCT have been reported to develop VOD, of which 18% of cases were fatal (Bhojwani et al. 2019). Here we report our institutional HCT experience in pediatric pts with r/r B-ALL who underwent HCT following INO reinduction and our strategy of using defibrotide prophylaxis to reduce the risk of VOD. Methods: A retrospective chart review was conducted for pts with r/r B-ALL who underwent HCT at our institution from December 2015 to January 2021. Clinical characteristics, laboratory parameters, and radiographic evaluations were reviewed. Patients who received ≥1 course of INO during reinduction were included in the INO group. Development of VOD was defined as a clinical diagnosis of VOD post-HCT based on either the Baltimore, Seattle, or European Society for Blood and Marrow Transplantation (EBMT) diagnostic criteria.Clinical characteristics were summarized. Time to VOD, graft versus host disease (GVHD), non-relapse mortality (NRM), and relapse were estimated under the competing risk setting, in which death without the event of interest was considered to be an absorbing competing risk. Results: Fifty-seven patients with relapsed or refractory B-ALL were transplanted between December 2015 and January 2021. Seventeen (30%) received at least 1 course (3 doses) of INO as part of their pre-HCT reinduction regimen. Fifty-five of 57 pts (97%), including all pts in the INO-group received a myeloablative regimen (51 total body irradiation/cyclophosphamide-based, 4 busulfan-based). Two patients in the non-INO group received a reduced-intensity regimen. Median time from last dose of INO to HCT (Day 0) was 34 days (range 24-71 days). Median number of INO doses received was 6 (range 3-9). Four patients had been transplanted previously, 1 in the INO group and 3 in the non-INO group. Two of these patients developed VOD during their current HCT, both from the non-INO group. Pts receiving INO were more likely to be transplanted in CR3 or higher, and to have required 3 regimens in reinduction to achieve that CR. Median follow-up was 20 months. Rates of VOD were similar between the INO (3 of 17, 18%) and non-INO (4 of 40, 10%) groups (p=0.4, Figure 1). All cases were severe or very severe by EBMT criteria. There was no VOD-related mortality in either group. Defibrotide prophylaxis was used in 82% (14 of 17) of pts in the INO group. Of the 3 patients in the INO group who developed VOD, 2 received defibrotide prophylaxis and 1 did not. Reasons to defer defibrotide prophylaxis included increased risk of CNS bleeding and provider preference. Defibrotide prophylaxis was used in 15% of pts in the non-INO group (6 of 40). In the non-INO group, 1 of 4 patients who developed VOD had received defibrotide prophylaxis. All pts received vitamin E and ursodiol per institutional practice. There were no treatment-related deaths in the INO group and no statistically significant differences were detected in (NRM) (0% vs 10%, p=0.25), median time to engraftment (24 vs 26.5 days, p=0.1), or GVHD (24% vs 55%, p=0.1) in the INO vs non-INO groups. Conclusions: HCT was well tolerated with low rates of VOD and NRM in pediatric pts following reinduction with INO. The results of ongoing prospective studies will provide further insight into the role of INO for reinduction of r/r B-ALL. In our cohort, rates of VOD were similar between pts who had and had not previously received INO, with the majority of pts in the INO group receiving defibrotide prophylaxis during HCT, suggesting that inotuzumab ozogamicin reinduction may safely be used with this approach. Figure 1 Figure 1. Disclosures Margossian: Cue Biopharma: Current Employment. Silverman: Takeda, Servier, Syndax, Jazz Pharmaceuticals: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Neuberg: Pharmacyclics: Research Funding; Madrigal Pharmaceuticals: Other: Stock ownership. OffLabel Disclosure: This study evaluates the safety of transplant following inotuzumab ozogamicin re-induction for children with B lymphoblastic leukemia.

Introduction: Increased toxicity with pegaspargase (PEG) in older and higher body mass index (BMI) patients (pts) with acute lymphoblastic leukemia (ALL) has recently led to dose capping practices. We assessed the influence of age, body surface area (BSA), and BMI on PEG-related toxicity and pharmacokinetics from two consecutive DFCI ALL Consortium trials without dose capping. Methods: Patient (pts) aged 1 to 0.1 IU/mL, was assessed 4, 11, 18, and 25 days after the Induction dose and nadir SAA was assessed before each Post-Induction dose. Asparaginase-related toxicities were prospectively assessed and graded by CTCAE version 3.0 (DFCI 05-001) or 4.0 (DFCI 11-001). Asparaginase toxicity for this analysis was defined as ≥1 of the following: pancreatitis, thrombosis, ≥grade 4 hyperbilirubinemia, ≥grade 4 hypertriglyceridemia. Allergy was analyzed separately (due to presumed dose independence). Height and weight at diagnosis were used for analyses. BMI categories were assigned using standard percentile ranges based on gender specific 2000 CDC growth charts. BSA was calculated using the Mosteller formula. Univariate analyses evaluated the relationship of age, BMI, and BSA with asparaginase toxicity. Comparisons of toxicity across BMI and BSA categories were performed using a Jonckheere-Terpstra test. Categorical comparisons for dichotomized BMI and BSA utilized a Fisher's exact test or chi square test. The relationships between BMI and BSA with toxicity were explored using multivariable models. Results: Between 4/2005-12/2011 802 pts enrolled on DFCI 05-001 and between 6/2012-6/2015 240 pts enrolled on DFCI 11-001. Both trials included random assignment of asparaginase formulation. In total 911 patients received pegaspargase during Induction and 351 during Post-Induction. During Induction, pts ≥15 years of age had higher asparaginase toxicity rates (17.1% vs 6.2%, p=0.0003) (Figure 1a). Toxicity differed significantly across BSA categories ( Post-Induction, age ≥15 years was associated with increased asparaginase toxicity (57.1% vs 21%, p Post-Induction, median nadir SAA levels were ≥0.1IU/mL for all BSA and age categories. Median SAA was similar or lower at all time-points for those ≥15 years of age compared with younger children. Median SAA for pts with BSA ≥1.5m 2 were similar or lower compared to those with BSA Conclusion: Age ≥15 years and BSA ≥2m 2 were each associated with significantly increased asparaginase toxicity. Older patients and those with higher BSA had similar or lower median SAA levels at all time-points. These results suggest that the differential toxicity seen in older patients and those with higher BSA is not explained by these patients having higher SAA levels. Prospective exploration of interventions to decrease toxicity in older patients and those with high BSA are needed. Figure 1 Figure 1. Disclosures Neuberg: Madrigal Pharmaceuticals: Other: Stock ownership; Pharmacyclics: Research Funding. Silverman: Takeda, Servier, Syndax, Jazz Pharmaceuticals: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees.

Background: In patients with ALL, inability to receive L-asparaginase therapy due to hypersensitivity is associated with higher relapse risk (Gupta S, et al. J Clin Oncol. 2020). JZP458 is a recombinant Erwinia asparaginase derived from a novel Pseudomonas fluorescens expression platform to produce a reliable supply of enzyme with minimal immunologic cross-reactivity to E. coli-derived asparaginases. It has an amino acid sequence identical to that of native Erwinia asparaginase and its activity on asparagine is comparable based on in vitro measurements. This report includes initial analyses from the phase 2/3 open-label, multicenter, confirmatory pharmacokinetic (PK) and safety study (NCT04145531) of JZP458 in patients with ALL/LBL who developed hypersensitivity or silent inactivation to a long-acting E. coli-derived asparaginase. Methods: For eligible patients, each remaining course of long-acting E. coli-derived asparaginase was substituted by six doses of intramuscular (IM) JZP458 on a Monday/Wednesday/Friday (M/W/F) schedule. The primary efficacy endpoint of the trial was evaluated by the proportion of patients with the last 72-hr (primary endpoint) and last 48-hr (key secondary endpoint) nadir serum asparaginase activity (NSAA) level ≥0.1 IU/mL during the first treatment course. Cohort 1a started with 25 mg/m 2 IM JZP458 (M/W/F) and Cohort 1b explored a higher dose of 37.5 mg/m 2 IM M/W/F. A preliminary population pharmacokinetic (PPK) model using Cohort 1a and 1b data predicted that a regimen of 25 mg/m 2 (M/W) and 50 mg/m 2 (F) would be optimal to support M/W/F dosing and Cohort 1c was initiated using this regimen. Results: This initial report (data cutoff of Jan 11, 2021) provides data from 102 study patients enrolled in Cohort 1a (n=33, 51.5% male), 1b (n=53, out of 87 patients enrolled, 62.3% male), and 1c (n=16, out of 52 patients enrolled, 50.0 % male). The median (range) number of courses received in Cohorts 1a, 1b, and 1c as of the data cutoff was 4 (1, 14), 3 (1, 12), and 1 (1, 2), respectively, and 53% of patients were ongoing in treatment. The mean serum asparaginase activity (SAA) levels (95% confidence intervals [CIs]) for evaluable patients in Cohorts 1a, 1b, and 1c at 48 hrs were 0.4489 IU/mL (0.3720, 0.5258), 0.8376 IU/mL (0.6813, 0.9939), and 0.5085 IU/mL (0.3261, 0.6908); and at 72 hrs were 0.1543 IU/mL (0.1162, 0.1924), 0.3000IU/mL (0.2269, 0.3730), and 0.3579 IU/mL (0.2184, 0.4974). The proportion of patients achieving NSAA ≥0.1 IU/mL at 48 and 72 hr time points are presented in Table 1. PPK modeling and simulation analysis suggested that JZP458 given IM as 25 mg/m 2 on M/W and 50 mg/m 2 on F was expected to achieve NSAA levels ≥0.1 IU/mL in 99.8% of patients (95% CI: 99.6%, 100%) at 48 hours and 97.3% of patients (95% CI: 96.5%, 98.0%) at 72 hours. Grade 3 or higher treatment-emergent adverse events, regardless of causality, occurred in 73/102 (72%) patients. Adverse drug reactions (ADRs) are shown in Table 2. These ADRs are consistent with the safety profile observed with other asparaginases. Conclusions: The JZP458 IM dosing regimen of 25 mg/m 2 M and W, and 50 mg/m 2 F demonstrates a positive benefit:risk profile, achieving SAA levels ≥0.1 IU/mL in >90% of patients studied at both 48- and 72-hrs and a safety profile that is consistent with what has been observed in published literature on asparaginases. Figure 1 Figure 1. Disclosures Maese: Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Loh: MediSix therapeutics: Membership on an entity's Board of Directors or advisory committees. Lin: Jazz Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Aoki: Jazz Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Zanette: Jazz Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Agarwal: Jazz Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Silverman: Jazz Pharmaceuticals: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. Choi: Jazz Pharmaceuticals: Current Employment, Current equity holder in publicly-traded company. Silverman: Takeda, Servier, Syndax, Jazz Pharmaceuticals: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Raetz: Pfizer: Research Funding; Celgene: Other: DSMB member. Rau: Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Advisory Board; Servier Pharmaceuticals: Consultancy; AbbVie Pharmaceuticals: Other: Spouse is employee and stock holder.

Introduction: Assessment of minimal residual disease (MRD) in a sensitive and timely manner is an essential component of risk stratification in childhood acute lymphoblastic leukemia (ALL). Next generation sequencing (NGS) assays utilize unique genetic sequences created by VDJ rearrangements in leukemia cells to detect MRD at the level of 1 leukemic cell in 1 million cells (Wood et al., 2018). Here we report our experience using NGS MRD for risk group assignment of children and adolescents with newly diagnosed ALL enrolled on the Dana Farber Cancer Institute (DFCI) ALL Consortium Protocol 16-001. Methods: Patients (pts) ages 1-21 years with B- or T-ALL were eligible for enrollment from 8 centers across the US and Canada. Initial risk status was assigned based on age, presenting leukocyte count, central nervous system (CNS) leukemia status, immunophenotype, and disease biology (Table 1). All patients underwent bone marrow evaluation at diagnosis and again upon completion of remission induction approximately four weeks later (Induction 1a, timepoint 1 (TP1)), with samples evaluated by flow cytometry (FCM) and NGS. NGS was primarily used for MRD-based risk determination, with FCM as a back-up test. Patients with high TP1 MRD (≥10 -4) received intensified therapy and underwent additional MRD assessments at 10 and 20 weeks of therapy. Multiparametric FCM was conducted locally for 7 of 8 sites in accordance with local CLIA certified lab practices. One site used centralized FCM. NGS MRD was assessed at Adaptive Biotechnologies Corporation, Seattle, WA using the commercially available assay ClonoSEQ ®. Clonality was evaluated at the immunoglobulin (Ig) heavy and light chain (IgH and IgL) and T cell receptor beta and gamma (TCR-B and TCR-G) loci with the maximal sequence used for MRD determination. Results: NGS evaluation of MRD is feasible A total of 317 patients enrolled on 16-001 between 2017 and 2020 were included in this analysis. Among this cohort, NGS identified unique trackable sequences in 98% of pts (N=310). Of the 7 pts without trackable sequences, 57% were pts with early T precursor (ETP) T-ALL (36% of all ETP pts tested). NGS detected trackable sequences in all non-ETP T-ALL pts (N=40), and 99% of B-ALL pts (N=263). Locus used for MRD determination Patients with B-ALL had a median of 5 trackable sequences (range 0-14) with 92% having at least one IgH and 64% having at least one TCR-G. For B-ALL, the highest MRD value at TP1 was determined by IGH locus in 44% (N=115) of pts and by TCR-G in 41% (N=109). The IgL or TCR-B locus yielded the highest TP1 MRD value in 15% (N=39). In contrast, pts with T-ALL had fewer trackable sequences with a median of 3 (range 0-8). While 28% (N=13) had at least one Ig sequence, the TCR locus was used for MRD determination in nearly all (98%, N=46) with 94% using TCR-G. Comparison of NGS and FCM MRD results NGS and FCM MRD values for 309 pts with results from both assays at TP1 are displayed in Figures 1a-d. Correlation was high between the two modalities for patients with detectable disease by both NGS and FCM (Pearson r=0.87, p For B-ALL pts with high MRD (N=70), 43% (N=30) were high by NGS (≥10 -4) when FCM was low ( Eight pts, all with B-ALL, had low NGS MRD when FCM was above the threshold of 10 -4. One patient had undetectable NGS MRD and the remaining 7 had NGS MRD in the range of 10 -6 to Conclusions: Delivery of risk adapted therapy for newly diagnosed pediatric pts with ALL utilizing an NGS MRD assay is feasible with evaluable MRD for 98% of patients in our cohort. Importantly, NGS identified more cases as having high MRD than FCM, with the majority of discrepant cases just above the FCM limit of detection (10 -4). NGS provided improved resolution in the range of 10 -6 to Figure 1 Figure 1. Disclosures Kirsch: Adaptive Biotechnologies: Current Employment, Current holder of stock options in a privately-held company. Silverman: Takeda, Servier, Syndax, Jazz Pharmaceuticals: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees.

Novel therapies are needed to overcome chemotherapy resistance for children with relapsed/refractory acute lymphoblastic leukemia (ALL). Moxetumomab pasudotox is a recombinant anti-CD22 immunotoxin. A multicenter phase 1 study was conducted to determine the maximum-tolerated cumulative dose (MTCD) and evaluate safety, activity, pharmacokinetics, and immunogenicity of moxetumomab pasudotox in children, adolescents, and young adults with ALL (N = 55). Moxetumomab pasudotox was administered as a 30-minute IV infusion at doses of 5 to 50 µg/kg every other day for 6 (cohorts A and B) or 10 (cohort C) doses in 21-day cycles. Cohorts B and C received dexamethasone prophylaxis against capillary leak syndrome (CLS). The most common treatment-related adverse events were reversible weight gain, hepatic transaminase elevation, and hypoalbuminemia. Dose-limiting CLS occurred in 2 of 4 patients receiving 30 µg/kg of moxetumomab pasudotox every other day for 6 doses. Incorporation of dexamethasone prevented further dose-limiting CLS. Six of 14 patients receiving 50 µg/kg of moxetumomab pasudotox for 10 doses developed hemolytic uremic syndrome (HUS), thrombotic microangiopathy (TMA), or HUS-like events, exceeding the MTCD. Treatment expansion at 40 µg/kg for 10 doses (n = 11) exceeded the MTCD because of 2 HUS/TMA/HUS-like events. Dose level 6B (ie, 50 µg/kg × 6 doses) was the MTCD, selected as the recommended phase 2 dose. Among 47 evaluable patients, an objective response rate of 32% was observed, including 11 (23%) composite complete responses, 5 of which were minimal residual disease negative by flow cytometry. Moxetumomab pasudotox showed a manageable safety profile and evidence of activity in relapsed or refractory childhood ALL. This trial was registered at www.clinicaltrials.gov as #NCT00659425.

Introduction: Hypersensitivity reactions with asparaginase occur frequently in pediatric patients (pts) with acute lymphoblastic leukemia (ALL). The standard approach for pts with reaction to E.coli-derived asparaginase is to switch to Erwinia asparaginase, given concern that clinical reactions reflect presence of neutralizing antibodies; however, Erwinia requires more frequent dosing and is often unavailable. Therapeutic drug monitoring allows for discrimination between pts with pegaspargase hypersensitivity who have sub-therapeutic asparaginase activity and those still able to derive therapeutic benefit from pegaspargase. We prospectively piloted re-challenging pts with pegaspargase after initial Grade 2 hypersensitivity to this agent, with premedication at re-challenge and assessment of serum asparaginase activity (SAA). Methods: Pts aged 1 to < 22 years with newly diagnosed ALL were eligible for DFCI 16-001. Pts received 1 dose of intravenous pegaspargase during Induction, and every 2 weeks for 15 total doses in Post-Induction phases, without routine premedication. Pts were monitored during/after pegaspargase for allergy, with CTCAE version 4.0 event grading. Those with ≥Grade 3 allergy discontinued pegaspargase and were switched to Erwinia. Those with Grade 2 allergic reaction were eligible for pegaspargase re-challenge with pre-medication (acetaminophen, diphenhydramine, and hydrocortisone, or per institutional standard) and slower infusion rate. If < 50% of the intended dose had been administered when reaction occurred, re-challenge was within 1-7 days of initial reaction. If ≥ 50% of the intended dose had been given, re-challenge was at next planned pegaspargase dose. SAA was measured 1-hour, 7-days, and 14-days after the re-challenge infusion (if dose completed). If 1-hour or 7-day level ≥ 0.1 IU/mL, and 14-day level ≥ 0.025 IU/mL, SAA was considered adequate, and the pt continued to receive pegaspargase with premedication. Pts with an inadequate SAA level, or with new ≥ Grade 2 allergic reaction with the re-challenge dose were considered to have failed re-challenge and were changed to Erwinia (or enrolled on a clinical trial of recombinant crisantaspase, an alternative Erwinia preparation). Results: Between 3/2017- 7/2020, 317 eligible pts enrolled. Overall, 81 of 299 (27%) total evaluable pts experienced a first allergic reaction to pegaspargase, 68 pts with Grade 2 reaction, 13 with Grade ≥3. During Induction, 17 of 299 (6%) evaluable pts had allergic reaction to pegaspargase; all Grade 2. Of the 17 Grade 2 reactions, 13 pts (76%) underwent re-challenge in Induction, 9 (69%) re-challenges successful and 4 failed. Post-Induction, 64 of 241 evaluable pts (27%) had a first allergic reaction; 51 Grade 2 and 13 Grade ≥3. Thirty-six of 51 (71%) pts with Grade 2 allergy during Post-Induction underwent re-challenge, as did 1 additional pt with allergy during Induction who was re-challenged with first Post-Induction pegaspargase dose (per protocol guideline, due to receiving ≥50% of Induction dose). Among these re-challenges, 16 were successful, 21 failed. Overall, 25 of 50 (50%) pts who were re-challenged after Grade 2 reaction had a successful challenge and were able to continue pegaspargase. Among the 25 pts with failed re-challenge, 6 pts (24%) had inadequate SAA alone as cause of failure, 17 pts (68%) had an allergic reaction with the re-challenge dose, and 2 (8%) additional patients had both allergic reaction and documented inadequate SAA. Three pts who were successfully re-challenged had a subsequent allergic reaction to pegaspargase. Among the 22 pts who experienced another allergic reaction with pegaspargase (at re-challenge or subsequent dose), 19 pts (86%) experienced Grade 2, and 3 pts experienced Grade 3 reaction. Conclusion: Fifty percent of pts with a Grade 2 reaction to pegaspargase were able to tolerate and achieve adequate SAA when re-challenged with premedication. For those who did react with or after re-challenge, reactions were not more severe. The re-challenge approach limits premedication exposure only to a minority of pts with a history of prior reaction and substantially decreases the number of pts needing to switch to Erwinia asparaginase, which can be challenging to deliver due to administration schedule and drug shortage. Disclosures Place: Novartis: Consultancy, Other: Institutional Research Funding; AbbVie: Consultancy. Silverman:Takeda: Other: advisory board; Servier: Other: advisory board; Syndax: Other: advisory board.

PURPOSE We determined the prognostic factors and utility of allogeneic hematopoietic cell transplantation among children with newly diagnosed hypodiploid acute lymphoblastic leukemia (ALL) treated in contemporary clinical trials. PATIENTS AND METHODS This retrospective study collected data on 306 patients with hypodiploid ALL who were enrolled in the protocols of 16 cooperative study groups or institutions between 1997 and 2013. The clinical and biologic characteristics, early therapeutic responses as determined by minimal residual disease (MRD) assessment, treatment with or without MRD-stratified protocols, and allogeneic transplantation were analyzed for their impact on outcome. RESULTS With a median follow-up of 6.6 years, the 5-year event-free survival rate was 55.1% (95% CI, 49.3% to 61.5%), and the 5-year overall survival rate was 61.2% (95% CI, 55.5% to 67.4%) for the 272 evaluable patients. Negative MRD at the end of remission induction, high hypodiploidy with 44 chromosomes, and treatment in MRD-stratified protocols were associated with a favorable prognosis, with a 5-year event-free survival rate of 75% (95% CI, 66.0% to 85.0%), 74% (95% CI, 61.0% to 89.0%), and 62% (95% CI, 55.0% to 69.0%), respectively. After exclusion of patients with high hypodiploidy with 44 chromosomes and adjustment for waiting time to transplantation and for covariables in a Poisson model, disease-free survival did not differ significantly ( P = .16) between the 42 patients who underwent transplantation and the 186 patients who received chemotherapy only, with an estimated 5-year survival rate of 59% (95% CI, 46.5% to 75.0%) versus 51.5% (95% CI, 44.7% to 59.4%), respectively. Transplantation produced no significant impact on outcome compared with chemotherapy alone, especially among the subgroup of patients who achieved a negative MRD status upon completion of remission induction. CONCLUSION MRD-stratified treatments improved the outcome for children with hypodiploid ALL. Allogeneic transplantation did not significantly improve outcome overall and, in particular, for patients who achieved MRD-negative status after induction.

PURPOSE Infant acute lymphoblastic leukemia (ALL) is characterized by KMT2A ( MLL) gene rearrangements and coexpression of myeloid markers. The Interfant-06 study, comprising 18 national and international study groups, tested whether myeloid-style consolidation chemotherapy is superior to lymphoid style, the role of stem-cell transplantation (SCT), and which factors had independent prognostic value. MATERIALS AND METHODS Three risk groups were defined: low risk (LR): KMT2A germline; high risk (HR): KMT2A-rearranged and older than 6 months with WBC count 300 × 109/L or more or a poor prednisone response; and medium risk (MR): all other KMT2A-rearranged cases. Patients in the MR and HR groups were randomly assigned to receive the lymphoid course low-dose cytosine arabinoside [araC], 6-mercaptopurine, cyclophosphamide (IB) or experimental myeloid courses, namely araC, daunorubicin, etoposide (ADE) and mitoxantrone, araC, etoposide (MAE). RESULTS A total of 651 infants were included, with 6-year event-free survival (EFS) and overall survival of 46.1% (SE, 2.1) and 58.2% (SE, 2.0). In West European/North American groups, 6-year EFS and overall survival were 49.4% (SE, 2.5) and 62.1% (SE, 2.4), which were 10% to 12% higher than in other countries. The 6-year probability of disease-free survival was comparable for the randomized arms (ADE+MAE 39.3% [SE 4.0; n = 169] v IB 36.8% [SE, 3.9; n = 161]; log-rank P = .47). The 6-year EFS rate of patients in the HR group was 20.9% (SE, 3.4) with the intention to undergo SCT; only 46% of them received SCT, because many had early events. KMT2A rearrangement was the strongest prognostic factor for EFS, followed by age, WBC count, and prednisone response. CONCLUSION Early intensification with postinduction myeloid-type chemotherapy courses did not significantly improve outcome for infant ALL compared with the lymphoid-type course IB. Outcome for infant ALL in Interfant-06 did not improve compared with that in Interfant-99.

Background Bacillus species are known to cause severe infection in immunocompromised hosts. The incidence of Bacillus bloodstream infections and characteristics of infection among children with cancer or indication for hematopoietic cell transplant (HCT) is unknown. Methods We performed a retrospective medical record review of all cases of Bacillus bacteremia between January 1, 2005, and December 31, 2014, at Boston Children's Hospital. We report average incidences from 2012 to 2014. We performed a detailed review of infections among children with cancer or undergoing HCT and a case-control study to evaluate whether neutropenia at diagnosis caries higher risk of Bacillus infection for children with acute lymphoblastic leukemia (ALL). Results One hundred fourteen children developed Bacillus bacteremia during the study period, with an estimated incidence of 0.27/1,000 patients. Among children treated for cancer or undergoing HCT, there were 37 bloodstream infections (2.0/1,000 patients). Of the 37 oncology/HCT patients, oncologic diagnoses included ALL (18), acute myeloid leukemia (3), myelodysplastic syndrome (1), solid tumors (8), and 7 children were undergoing HCT. The incidence of infection among children with ALL was 34/1,000 patients and all central nervous system (CNS) infections (6) and deaths (3) occurred in this population. Neutropenia at time of diagnosis in children with ALL was not associated with risk of infection (P = 0.17). Discussion We report the first hospital-wide analysis of Bacillus infection and found that immunocompromised children experience a significant proportion of Bacillus infections. Children with ALL have a high incidence of infection and are at higher risk of CNS involvement and death.

10031 Background: Asparaginase (ASN) is a crucial component of pediatric acute lymphoblastic leukemia (ALL) protocols. ASN is available in three enzyme formulations: native from Escherichia Coli ( E. coli), PEGylated from E. coli (PEG), and native erwinia from Erwinia chrysanthemi (Erwinase). PEG is typically preferred in high-income countries, while E. coli is more accessible in low and middle income countries (LMICs). Erwinase is reserved for patients who develop hypersensitivity. Short shelf lives, high prices, intermittent availability, and concern for substandard formulations in LMICs have created a need for proactive ASN demand estimates, particularly in LMICs. Methods: We modified FORxECAST, a publicly available tool that forecasts pediatric cancer drug quantity and cost, to estimate ASN quantity required to treat pediatric ALL in 2021 across all LMICs. Incidence data is based on the Global Childhood Cancer microsimulation model, which extrapolates country registries to estimate diagnosed pediatric ALL patients. We forecast ASN quantity for both a base regimen (BR), recommended by the International Pediatric Oncology Society (SIOP), and a more aggressive regimen (AR) used in some LMICs with more advanced supportive care capacity. For both BR and AR, we estimate ASN quantity across four scenarios, outlining how quantity would vary based on formulation and ability to switch in cases of hypersensitivity. Results: The estimated quantity of ASN required to treat all children diagnosed with ALL in LMICs in 2021, across scenarios and regimens, is provided (Table). If E. coli were used to treat all diagnosed pediatric ALL patients across LMICs, required quantity would range from 1,198 M IU (BR) to 1,661 M IU (AR) (Scenario 1). If PEG were used, required quantity would range 150 M IU (BR) to 473 M IU (AR) (Scenario 2). Accounting for hypersensitivity would require 77 M IU (BR) to 137 M IU (AR) Erwinase (Scenarios 3 and 4). Conclusions: We adapted FORxECAST to be ASN-specific and estimated demand in LMICs for a range of scenarios, including for second line Erwinase; accounting for hypersensitivity is particularly important because discontinuation typically results in lower cure rates. We also estimated how quantity of ASN required would increase with treatment intensity. These results provide the first quantification of ASN need for pediatric ALL in LMICs, creating a demand estimate that can inform private and public efforts to produce a reliable supply of high quality ASN for all children with ALL.[Table: see text]

10025 Background: Poverty is associated with inferior psychosocial function among parents of children with cancer. Severe parental distress during treatment predicts future poor mental health for both parents and children. It is also associated with impaired parental cognitive bandwidth and executive function, which may have implications for treatment adherence. Efforts to identify poverty-exposures amenable to intervention are essential to improving survivorship quality of life for the > 90% of children with acute lymphoblastic leukemia (ALL) who will be long-term survivors. Household material hardship (HMH) is a targetable poverty exposure defined as at least 1 of 3 unmet basic needs including food, housing, or utilities. Dana-Farber Cancer Institute (DFCI) ALL Consortium trial 16-001 is the first pediatric oncology clinical trial to systematically evaluate HMH. We investigated the hypothesis that HMH exposure independently predicts severe parent psychological distress during ALL therapy. Methods: Patients with newly diagnosed ALL ages 1-17 years were enrolled on the DFCI 16-001 embedded HMH cohort study at 8 U.S. and Canadian centers. Secondary interim analyses used baseline (within 32-days of trial enrollment) and 6-mos parent-reported sociodemographic data, the Kessler-6 (K6) Psychological Distress scale, and trial-collected child and disease data. Severe psychological distress was defined as a K6 > = 13. Multivariable cox regression evaluated baseline HMH-exposure and parent distress at baseline and 6-mos adjusting for child’s initial ALL risk group (Very High Risk (VHR) vs other) and marital status (single vs dual parent). Results: Among 258 families with evaluable data, 34% reported baseline HMH. Families were predominantly English-speaking (54%) dual parent households (71%). Children were a median of 5.7 years (IQR 1.0-17.99) at diagnosis and predominantly non-Hispanic white (66%) with expected disease distribution by immunophenotype (84% B-cell). HMH (odds ratio (OR) 2.18, 95% confidence interval (CI) 1.0-4.31, p = 0.025) and VHR initial risk group (OR 2.32; 95% CI 1.06-5.06, p = 0.035) were independently associated with baseline severe psychological distress. Only HMH was independently associated with 6-mos severe psychological distress (OR 4.93, 95% CI 1.80-13.48, p = 0.002). Future analyses will investigate race and ethnicity associations with parental distress pending trial accrual for statistical power. Conclusions: HMH, a modifiable poverty exposure, is significantly associated with severe parent psychological distress at diagnosis that persists 6-months into pediatric ALL therapy. These findings identify a cohort at high risk of inferior mental health outcomes, and affirm the need for HMH-targeted interventions to support children and parents during cancer treatment to reduce poverty-associated outcome disparities in survivorship.

While the majority of children and adolescents with newly diagnosed childhood acute lymphoblastic leukemia (ALL) will be cured, as many as 20 % of patients will experience relapse. On current treatment regimens, the intensity of upfront treatment is stratified based upon prognostic factors with the aim of improving cure rates (for those at the highest risk of relapse) and minimizing treatment-related morbidity (for lower-risk patients). Here we review advances in the understanding of prognostic factors and their application. We also highlight novel treatment approaches aimed at improving outcomes in childhood ALL.

Background Population-based evidence suggests that lower socioeconomic status (SES) negatively impacts the overall survival (OS) of children with leukemia; however, the relationships between SES and treatment-related mortality, relapse, and timing of relapse remain unclear. Procedure We examined OS, event-free survival (EFS) and cumulative incidence (CI) and timing of relapse by community-level poverty for 575 children aged 1–18 years with newly diagnosed acute lymphoblastic leukemia (ALL) treated on consecutive phase III multicenter Dana-Farber Cancer Institute ALL Consortium Protocols between 2000 and 2010. Children were categorized into high- and low-poverty areas for the analysis using aggregate U.S. Census data linked to zip code. Results Children living in high-poverty areas experienced a 5-year OS of 85% as compared with 92% for those in low-poverty areas (P = 0.02); poverty remained marginally significant (P = 0.07) after adjustment for immunophenotype, age, and white blood cell count. There were no differences detected in EFS or CI relapse by poverty area. However, 92% of the relapses observed in children from high-poverty areas occurred

BACKGROUND Impaired cardiac function in doxorubicin-treated childhood cancer survivors is partly mediated by the disruption of mitochondrial energy production. Doxorubicin intercalates into mitochondrial DNA (mtDNA) and disrupts genes encoding for polypeptides that make adenosine triphosphate. METHODS This cross-sectional study examined mtDNA copy numbers per cell and oxidative phosphorylation (OXPHOS) in peripheral blood mononuclear cells (PBMCs) in 64 childhood survivors of high-risk acute lymphoblastic leukemia (ALL) who had been treated on Dana-Farber Cancer Institute childhood ALL protocols and had received doxorubicin alone (42%) or doxorubicin with the cardioprotectant dexrazoxane (58%). The number of mtDNA copies per cell and the OXPHOS enzyme activity of nicotinamide adenine dinucleotide dehydrogenase (complex I [CI]) and cytochrome c oxidase (complex IV [CIV]) were measured with quantitative real-time polymerase chain reaction immunoassays and thin-layer chromatography, respectively. RESULTS At a median follow-up of 7.8 years after treatment, the median number of mtDNA copies per cell for patients treated with doxorubicin alone (1106.3) was significantly higher than the median number for those who had also received dexrazoxane (310.5; P = .001). No significant differences were detected between the groups for CI or CIV activity. CONCLUSIONS Doxorubicin-treated survivors had an increased number of PBMC mtDNA copies per cell, and concomitant use of dexrazoxane was associated with a lower number of mtDNA copies per cell. Because of a possible compensatory increase in mtDNA copies per cell to maintain mitochondrial function in the setting of mitochondrial dysfunction, overall OXPHOS activity was not different between the groups. The long-term sustainability of this compensatory response in these survivors at risk for cardiac dysfunction over their lifespan is concerning. Cancer 2016;122:946–53. © 2016 American Cancer Society.

Summary Background l-asparaginase is a universal component of treatment for childhood acute lymphoblastic leukaemia, and is usually administered intramuscularly. Pegylated Escherichia coli asparaginase (PEG-asparaginase) has a longer half-life and is potentially less immunogenic than the native Escherichia coli ( E coli ) preparation, and can be more feasibly administered intravenously. The aim of the Dana-Farber Cancer Institute Acute Lymphoblastic Leukaemia Consortium Protocol 05-001 (DFCI 05-001) was to compare the relative toxicity and efficacy of intravenous PEG-asparaginase and intramuscular native E coli l-asparaginase in children with newly diagnosed acute lymphoblastic leukaemia. Methods DFCI 05-001 enrolled patients aged 1–18 years with newly diagnosed acute lymphoblastic leukaemia from 11 consortium sites in the USA and Canada. Patients were assigned to an initial risk group on the basis of their baseline characteristics and then underwent 32 days of induction therapy. Those who achieved complete remission after induction therapy were assigned to a final risk group and were eligible to participate in a randomised comparison of intravenous PEG-asparaginase (15 doses of 2500 IU/m 2 every 2 weeks) or intramuscular native E coli l-asparaginase (30 doses of 25 000 IU/m 2 weekly), beginning at week 7 after study entry. Randomisation (1:1) was unmasked, and was done by a statistician-generated allocation sequence using a permuted blocks algorithm (block size of 4), stratified by final risk group. The primary endpoint of the randomised comparison was the overall frequency of asparaginase-related toxicities (defined as allergy, pancreatitis, and thrombotic or bleeding complications). Predefined secondary endpoints were disease-free survival, serum asparaginase activity, and quality of life during therapy as assessed by PedsQL surveys. All analyses were done by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00400946. Findings Between April 22, 2005, and Feb 12, 2010, 551 eligible patients were enrolled. 526 patients achieved complete remission after induction, of whom 463 were randomly assigned to receive intramuscular native E coli l-asparaginase (n=231) or intravenous PEG-asparaginase (n=232). The two treatment groups did not differ significantly in the overall frequency of asparaginase-related toxicities (65 [28%] of 232 patients in the intravenous PEG-asparaginase group vs 59 [26%] of 231 patients in the intramuscular native E coli l-asparaginase group, p=0·60), or in the individual frequency of allergy (p=0·36), pancreatitis (p=0·55), or thrombotic or bleeding complications (p=0·26). Median follow-up was 6·0 years (IQR 5·0–7·1). 5-year disease-free survival was 90% (95% CI 86–94) for patients assigned to intravenous PEG-asparaginase and 89% (85–93) for those assigned to intramuscular native E coli l-asparaginase (p=0·58). The median nadir serum asparaginase activity was significantly higher in patients who received intravenous PEG-asparaginase than in those who received intramuscular native E coli l-asparaginase. Significantly more anxiety was reported by both patients and parent-proxy in the intramuscular native E coli l-asparaginase group than in the intravenous PEG-asparaginase group. Scores for other domains were similar between the groups. The most common grade 3 or worse adverse events were bacterial or fungal infections (47 [20%] of 232 in the intravenous PEG-asparaginase group vs 51 [22%] of 231 patients in the intramuscular E coli l-asparaginase group) and asparaginase-related allergic reactions (14 [6%] vs 6 [3%]). Interpretation Intravenous PEG-asparaginase was not more toxic than, was similarly efficacious to, and was associated with decreased anxiety compared with intramuscular native E coli l-asparaginase, supporting its use as the front-line asparaginase preparation in children with newly diagnosed acute lymphoblastic leukaemia. Funding National Cancer Institute and Enzon Pharmaceuticals.

Introduction: Ph+ ALL accounts for 3-5% of pediatric ALL and is associated with improved outcomes when tyrosine kinase inhibitors (TKIs) are added to chemotherapy, with 5-year event-free survival (EFS) and overall survival (OS) of 58-60% and 70-86%, respectively. Ponatinib is a potent third-generation TKI pan-BCR-ABL1 inhibitor that is active against BCR-ABL1 and all identified single resistance mutations, including the gatekeeper alteration, T315I, which confers resistance to other TKIs. Ponatinib has marketing approval in more than 50 countries, which includes the United States and European Union, for adults with chronic-/accelerated-/blast-phase chronic myeloid leukemia or Ph+ ALL that are resistant/intolerant to other TKIs or are T315I+. Ponatinib may also overcome drug resistance in pediatric patients with relapsed or resistant Ph+ ALL. This study will assess the pharmacokinetics, safety, and efficacy of ponatinib in pediatric patients. Methods: This Phase 1/2, single-arm, open-label, multicenter study (NCT04501614) will enroll approximately 18 patients in Phase 1 and 68 patients in Phase 2, including those enrolled in Phase 1 at the recommended Phase 2 dose (RP2D). Patients (aged ≥1 year to ≤21 years) with Ph+ ALL, Ph+ mixed phenotype acute leukemia, or Ph-like ALL (US only) with ABL class lesions will be enrolled. Enrolled patients must have either relapsed or are resistant or intolerant to ≥1 prior therapy with a BCR-ABL1-targeted TKI or have a BCR-ABL1 T315I mutation. Patients >16 years must have a Karnofsky performance status ≥50%; patients ≤16 years must have a Lansky Play Scale ≥50%. During Phase 1, prior to availability of an age-appropriate formulation (AAF), patients must weigh ≥30 kg and be able to swallow tablets. The Phase 1 study will establish the RP2D of ponatinib in combination with the chemotherapy backbone using the adult tablet formulation in patients able to swallow tablets. Patients will receive fixed doses of ponatinib based on body weight ranges. The initially selected doses are expected to achieve systemic exposures that approximately match adult exposures after a 30-mg dose. Dose selection for the AAF will be in a separate cohort and informed by the results of a relative bioavailability study in healthy adult volunteers. A rolling 6 design will be used for both cohorts; additional cohorts may be enrolled at lower or higher doses based on the emerging data. In both Phase 1 and Phase 2, patients will receive two 35-day blocks of therapy (reinduction and consolidation). Each block includes 29 days of study treatment consisting of daily ponatinib and a modified United Kingdom ALL R3 chemotherapy backbone regimen, followed by a rest period of at least 6 days with daily ponatinib only. Disease assessment will occur at the end of each block. Patients will undergo an end-of-treatment visit 25 to 30 days after the last dose of study treatment in the consolidation block, or earlier if the patient is proceeding to alternate therapy or optional ponatinib continuation therapy. For the Phase 1 study, the primary endpoint is the RP2D of ponatinib (tablet and AAF) in combination with chemotherapy. Secondary endpoints are complete response (CR) rate at the end of the reinduction block and characterization of BCR-ABL1 domain mutations prior to and following ponatinib treatment. For the Phase 2 study, the primary endpoint is the CR rate at the end of the reinduction block. Secondary endpoints will be summarized descriptively, and include the proportion of patients in continued CR or who achieve CR at the end of consolidation, the proportion with minimal residual disease-negative status Disclosures Matloub: Takeda: Current Employment. Gore:Amgen, Novartis, Roche: Membership on an entity's Board of Directors or advisory committees. Loh:Medisix Therapeutics: Membership on an entity's Board of Directors or advisory committees; Pfizer: Other: Institutional Research Funding. Pui:Adaptive Biotechnologies: Membership on an entity's Board of Directors or advisory committees. Hanley:Takeda: Current Employment. Lu:Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Current Employment. Leonard:Takeda: Current Employment. Granier:Incyte: Current Employment. Silverman:Servier: Other: advisory board; Syndax: Other: advisory board; Takeda: Other: advisory board. OffLabel Disclosure: Ponatinib has marketing approval in the United States and European Union for adult patients with chronic-/accelerated-/blast-phase chronic myeloid leukemia or Ph+ ALL that are resistant/intolerant to other TKIs or are T315I+. This trials-in-progress abstract describes a study in pediatric patients.

10512 Background: PI3K/mTOR signaling, a critical pathway in cell proliferation, metabolism, and apoptosis, is often dysregulated in acute lymphoblastic leukemia (ALL). A phase 1 trial of the mTOR inhibitor temsirolimus combined with etoposide and cyclophosphamide was performed in children with relapsed/refractory (r/r) ALL. Methods: Temsirolimus was administered intravenously (IV) on days 1 and 8 with cyclophosphamide 440 mg/m2 and etoposide 100 mg/m2 IV daily days 1-5. The starting dose level (DL) of temsirolimus was 7.5 mg/m2 (DL1) with escalation to 10 mg/m2 (DL2), 15 mg/m2 (DL3), and 25 mg/m2 (DL4). MRD was performed centrally. PI3K pathway inhibition was measured by phosphoflow cytometry (PFC) analysis of peripheral blood (PB) from treated patients (pts). Results: Sixteen heavily pretreated r/r ALL pts ages 2-19 years with marrow blasts > 25% were enrolled; 15 were evaluable [10 B-ALL/5 T-ALL]. One dose-limiting toxicity (DLT) of grade (Gr) 4 pleural and pericardial effusions with pneumonitis/lung infection leading to Gr 5 cardiorespiratory arrest occurred in a pt treated at DL3. No further DLTs were seen in the DL3 expansion and DL4 cohorts. Gr 3/4 non-hematologic toxicities occurring in ≥ 3 pts included febrile neutropenia, elevated ALT, hypokalemia, mucositis, and tumor lysis syndrome and were independent of dose. Of 15 evaluable pts, 4 (27%; 2 B-ALL/2 T-ALL) had a complete response (CR) after cycle 1, comprised of 1 pt at each DL. Three had MRD < 0.01%. Three pts (20%; 2 B-ALL/1 T-ALL) had partial response (PR). Overall response rate (CR+PR = ORR) was 47%. Pharmacodynamic PFC studies compared phosphoprotein levels pre (day 0) and post treatment (days 3-5) in 9 consenting pts with available PB. All tested pts showed basal activation of PI3K pathway signaling. Dose-dependent inhibition of mTOR targets phosphorylated (p) S6 and/or p4EBP1 was observed in 9/9 and 6/9 pts, respectively, following temsirolimus and chemotherapy treatment. Various patterns of compensatory upregulation of pPI3K, pmTOR, pAkt, and/or pERK was observed. Conclusions: Temsirolimus at 25 mg/m2 combined with salvage etoposide and cyclophosphamide has an acceptable safety profile in high-risk pediatric patients with r/r ALL. Responses were observed at all DLs. mTOR target inhibition was achieved and appeared to correlate with dose level. Future testing of other PI3K/mTOR pathway inhibitors in combination with chemotherapy may be warranted with a goal of further increasing response in r/r ALL. Clinical trial information: NCT01614197.

Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Nutritional morbidities are a persistent problem facing pediatric patients during and after treatment and age-gender groups that are at risk for nutritional conditions have not been clearly identified. Therapy is a contributing factor; however, the role of dietary intake remains largely unknown. Prior to conduct of interventional trials, an understanding of the effects of treatment on fluctuations in dietary intake is necessary.We enrolled 794 children with ALL in a prospective clinical trial. Dietary intake was collected with a food frequency questionnaire at diagnosis and throughout the course of treatment for pediatric ALL. Reported values were compared to the Dietary Recommended Intake (DRI), and normative values (NHANES). Hierarchical linear models and multilevel mixed-effects ordered logistic regression models were used to evaluate longitudinal changes in dietary intake; independent samples t-test with Bonferroni correction was performed to compare to NHANES.Of the evaluable participants at each timepoint, dietary intake was obtained on 81% (n = 640), 74% (n = 580) and 74% (n = 558) at diagnosis, end of induction phase of treatment, and continuation, respectively. Despite exposure to corticosteroids, caloric intake decreased over therapy for most age-gender groups. Predictive models of excess intake found reduced odds of over-consuming calories (OR 0.738, P 0.05); however, increased odds of over-consuming fat (OR 6.971, P 0.001). When compared to NHANES, we consistently found that ≥1/3 of children were consuming calories in excess of normative values. For select micronutrients, a small proportion of participants were above or below the DRI at each time evaluated.Our study suggests that dietary intake fluctuates during treatment for ALL as compared to age-gender recommended and normative values. Improving our understanding of nutrient fluctuations and dietary quality will facilitate subsequent analyses addressing relationships of dietary intake, toxicity, and survival.

Purpose Addition of imatinib to intensive chemotherapy improved survival for children and young adults with Philadelphia chromosome–positive acute lymphoblastic leukemia. Compared with imatinib, dasatinib has increased potency, CNS penetration, and activity against imatinib-resistant clones. Patients and Methods Children’s Oncology Group (COG) trial AALL0622 (Bristol Myers Squibb trial CA180-204) tested safety and feasibility of adding dasatinib to intensive chemotherapy starting at induction day 15 in patients with newly diagnosed Philadelphia chromosome–positive acute lymphoblastic leukemia age 1 to 30 years. Allogeneic hematopoietic stem-cell transplantation (HSCT) was recommended for patients at high risk based on slow response and for those with a matched family donor regardless of response after at least 11 weeks of therapy. Patients at standard risk based on rapid response received chemotherapy plus dasatinib for an additional 120 weeks. Patients with overt CNS leukemia received cranial irradiation. Results Sixty eligible patients were enrolled. Five-year overall (OS) and event-free survival rates (± standard deviations [SD]) were 86% ± 5% and 60% ± 7% overall, 87% ± 5% and 61% ± 7% for standard-risk patients (n = 48; 19% underwent HSCT), and 89% ± 13% and 67% ± 19% for high-risk patients (n = 9; 89% underwent HSCT), respectively. Five-year cumulative incidence (± SD) of CNS relapse was 15% ± 6%. Outcomes (± SDs) were similar to those in COG AALL0031, which used the same chemotherapy with continuous imatinib: 5-year OS of 81% ± 6% versus 86% ± 5% ( P = .63) and 5-year disease-free survival of 68% ± 7% versus 60% ± 7% ( P = 0.31) for AALL0031 versus AALL0622, respectively. IKZF1 deletions, present in 56% of tested patients, were associated with significantly inferior OS and event-free survival overall and in standard-risk patients. Conclusion Dasatinib was well tolerated with chemotherapy and provided outcomes similar to those with imatinib in COG AALL0031, where all patients received cranial irradiation. Our results support limiting HSCT to slow responders and suggest a potential role for transplantation in rapid responders with IKZF1 deletions.

BACKGROUND Children and adolescents with Down syndrome (DS) and acute lymphoblastic leukemia (ALL) are reported to have increased relapse rates and therapy-related mortality (TRM). Treatment regimens for DS-ALL patients often include therapy modifications. Dana-Farber Cancer Institute (DFCI) ALL Consortium protocols have used same risk-stratified treatment for patients with and without DS. PROCEDURES We compared clinical and outcome data of DS (n = 38) and non-DS (n = 1,248) patients enrolled on two consecutive DFCI ALL trials 00-001 (2000-2004) and 05-001 (2005-2011) with similar risk adapted therapy regardless of DS status. RESULTS There was no difference in demographic or presenting clinical features between two groups except absence of T-cell phenotype and lower frequency of hyperdiploidy in DS-ALL group. All DS-ALL patients achieved complete remission; four relapsed and one subsequently died. There was no TRM in DS-ALL patients. DS-ALL patients had significantly higher rates of mucositis (52% vs. 12%, p