BACKGROUND: Acute myeloid leukemia (AML) with megakaryocytic differentiation (AMkL) is a rare subtype of AML more common in children. Recent literature has identified multiple fusions associated with this type of leukemia.

METHODS: Morphology, cytogenetics, and genomic sequencing were assessed in patients from Children's Oncology Group trials AAML0531 and AAML1031 with central-pathology review confirmed non-Down syndrome AMkL. The 5-year event-free survival (EFS), overall survival (OS), and RR were evaluated in these AMkL subcategories.

RESULTS: A total of 107 cases of AMkL (5.5%) were included. Distinct fusions were identified in the majority: RBM15::MRTFA (20%), CBFA2T3::GLIS2 (16%), NUP98 (10%), KMT2A (7%), TEC::MLLT10 (2%), MECOM (1%), and FUS::ERG (1%); many of the remaining cases were classified as AMkL with (other) myelodysplasia-related changes (MRC). Very few cases had AML-associated somatic mutations. Cases with CBFA2T3::GLIS2 were enriched in trisomy 3 (p = .015) and the RAM phenotype, with associated high CD56 expression (p < .001). Cases with NUP98 fusions were enriched in trisomy 6 (p < .001), monosomy 13/del(13q) (p < .001), trisomy 21 (p = .026), and/or complex karyotypes (p = .026). While different 5-year EFS and OS were observed in AMkL in each trial, in general, those with CBFA2T3::GLIS2 or KMT2A rearrangements had worse outcomes compared to other AMkL, while those with RBM15::MRTFA or classified as AMkl-MRC fared better. AMkL with NUP98 fusions also had poor outcomes in the AAML1031 trial.

CONCLUSION: Given the differences in outcomes, AMkL classification by fusions, cytogenetics, and morphology may be warranted to help in risk stratification and therapeutic options.

PURPOSE: Optimized strategies for risk classification are essential to tailor therapy for patients with biologically distinctive disease. Risk classification in pediatric acute myeloid leukemia (pAML) relies on detection of translocations and gene mutations. Long noncoding RNA (lncRNA) transcripts have been shown to associate with and mediate malignant phenotypes in acute myeloid leukemia (AML) but have not been comprehensively evaluated in pAML.

METHODS: To identify lncRNA transcripts associated with outcomes, we evaluated the annotated lncRNA landscape by transcript sequencing of 1,298 pediatric and 96 adult AML specimens. Upregulated lncRNAs identified in the pAML training set were used to establish a regularized Cox regression model of event-free survival (EFS), yielding a 37 lncRNA signature (lncScore). Discretized lncScores were correlated with initial and postinduction treatment outcomes using Cox proportional hazards models in validation sets. Predictive model performance was compared with standard stratification methods by concordance analysis.

RESULTS: Training set cases with positive lncScores had 5-year EFS and overall survival rates of 26.7% and 42.7%, respectively, compared with 56.9% and 76.3% with negative lncScores (hazard ratio, 2.48 and 3.16; < .001). Pediatric validation cohorts and an adult AML group yielded comparable results in magnitude and significance. lncScore remained independently prognostic in multivariable models, including key factors used in preinduction and postinduction risk stratification. Subgroup analysis suggested that lncScores provide additional outcome information in heterogeneous subgroups currently classified as indeterminate risk. Concordance analysis showed that lncScore adds to overall classification accuracy with at least comparable predictive performance to current stratification methods that rely on multiple assays.

CONCLUSION: Inclusion of the lncScore enhances predictive power of traditional cytogenetic and mutation-defined stratification in pAML with potential, as a single assay, to replace these complex stratification schemes with comparable predictive accuracy.

Cytarabine arabinoside (Ara-C) has been the cornerstone of AML chemotherapy for decades. Following cellular uptake, it is phosphorylated into its active triphosphate form (Ara-CTP), which primarily exerts its cytotoxic effects by inhibiting DNA synthesis in proliferating cells. Interpatient variation in the enzymes involved in the Ara-C metabolic pathway have been shown to impact intracellular abundance of Ara-CTP and thus its therapeutic benefit. Recently, SAMHD1 (SAM and HD domain containing deoxynucleoside triphosphate triphosphohydrolase 1) has emerged to play a role in Ara-CTP inactivation, development of drug resistance and consequently, clinical response in AML. Despite this the impact of genetic variations in SAMHD1 on outcome in AML has not been investigated in depth. In this study, we evaluated 25 single nucleotide polymorphisms (SNPs) within SAMHD1 gene for association with clinical outcome in 400 newly diagnosed pediatric AML patients from two clinical trials- AML02 and AML08. Three SNPs, rs1291128, rs1291141, and rs7265241 located in the 3' region of SAMHD1 were significantly associated with at least one clinical outcome endpoint: minimal residual disease (MRD) after induction I, event free survival (EFS), or overall survival (OS) in the two cohorts. In an independent cohort of patients from COG-AAML1031 trial (n=854), rs7265241 A>G remained significantly associated with EFS and OS. In multivariable analysis, adjusting for other prognostic factors such as race, age, risk group, and white blood cell count, all the SNPs remained independent predictors of clinical outcome endpoints. These results highlight the relevance of the SAMHD1 pharmacogenomics in context of response to Ara-C in AML and warrants the need for further validation in expanded patient cohorts.

BACKGROUND: Adverse events are often misreported in clinical trials, leading to an incomplete understanding of toxicities. We aimed to test automated laboratory adverse event ascertainment and grading (via the ExtractEHR automated package) to assess its scalability and define adverse event rates for children with acute myeloid leukaemia and acute lymphoblastic leukaemia.

METHODS: For this retrospective cohort study from the Children's Oncology Group (COG), we included patients aged 0-22 years treated for acute myeloid leukaemia or acute lymphoblastic leukaemia at Children's Healthcare of Atlanta (Atlanta, GA, USA) from Jan 1, 2010, to Nov 1, 2018, at the Children's Hospital of Philadelphia (Philadelphia, PA, USA) from Jan 1, 2011, to Dec 31, 2014, and at the Texas Children's Hospital (Houston, TX, USA) from Jan 1, 2011, to Dec 31, 2014. The ExtractEHR automated package acquired, cleaned, and graded laboratory data as per Common Terminology Criteria for Adverse Events (CTCAE) version 5 for 22 commonly evaluated grade 3-4 adverse events (fatal events were not evaluated) with numerically based CTCAE definitions. Descriptive statistics tabulated adverse event frequencies. Adverse events ascertained by ExtractEHR were compared to manually reported adverse events for patients enrolled in two COG trials (AAML1031, NCT01371981; AALL0932, NCT02883049). Analyses were restricted to protocol-defined chemotherapy courses (induction I, induction II, intensification I, intensification II, and intensification III for acute myeloid leukaemia; induction, consolidation, interim maintenance, delayed intensification, and maintenance for acute lymphoblastic leukaemia).

FINDINGS: Laboratory adverse event data from 1077 patients (583 from Children's Healthcare of Atlanta, 200 from the Children's Hospital of Philadelphia, and 294 from the Texas Children's Hospital) who underwent 4611 courses (549 for acute myeloid leukaemia and 4062 for acute lymphoblastic leukaemia) were extracted, processed, and graded. Of the 166 patients with acute myeloid leukaemia, 86 (52%) were female, 80 (48%) were male, 96 (58%) were White, and 132 (80%) were non-Hispanic. Of the 911 patients with acute lymphoblastic leukaemia, 406 (45%) were female, 505 (55%) were male, 596 (65%) were White, and 641 (70%) were non-Hispanic. Patients with acute myeloid leukaemia had the most adverse events during induction I and intensification II. Hypokalaemia (one [17%] of six to 75 [48%] of 156 courses) and alanine aminotransferase (ALT) increased (13 [10%] of 134 to 27 [17%] of 156 courses) were the most prevalent non-haematological adverse events in patients with acute myeloid leukaemia, as identified by ExtractEHR. Patients with acute lymphoblastic leukaemia had the greatest number of adverse events during induction and maintenance (eight adverse events with prevalence ≥10%; induction and maintenance: anaemia, platelet count decreased, white blood cell count decreased, neutrophil count decreased, lymphocyte count decreased, ALT increased, and hypocalcaemia; induction: hypokalaemia; maintenance: aspartate aminotransferase [AST] increased and blood bilirubin increased), as identified by ExtractEHR. 187 (85%) of 220 total comparisons in 22 adverse events in four AAML1031 and six AALL0923 courses were substantially higher with ExtractEHR than COG-reported adverse event rates for adverse events with a prevalence of at least 2%.

INTERPRETATION: ExtractEHR is scalable and accurately defines laboratory adverse event rates for paediatric acute leukaemia; moreover, ExtractEHR seems to detect higher rates of laboratory adverse events than those reported in COG trials. These rates can be used for comparisons between therapies and to counsel patients treated on or off trials about the risks of chemotherapy. ExtractEHR-based adverse event ascertainment can improve reporting of laboratory adverse events in clinical trials.

FUNDING: US National Institutes of Health, St Baldrick's Foundation, and Alex's Lemonade Stand Foundation.

BACKGROUND: Adverse events are often misreported in clinical trials, leading to an incomplete understanding of toxicities. We aimed to test automated laboratory adverse event ascertainment and grading (via the ExtractEHR automated package) to assess its scalability and define adverse event rates for children with acute myeloid leukaemia and acute lymphoblastic leukaemia.

METHODS: For this retrospective cohort study from the Children's Oncology Group (COG), we included patients aged 0-22 years treated for acute myeloid leukaemia or acute lymphoblastic leukaemia at Children's Healthcare of Atlanta (Atlanta, GA, USA) from Jan 1, 2010, to Nov 1, 2018, at the Children's Hospital of Philadelphia (Philadelphia, PA, USA) from Jan 1, 2011, to Dec 31, 2014, and at the Texas Children's Hospital (Houston, TX, USA) from Jan 1, 2011, to Dec 31, 2014. The ExtractEHR automated package acquired, cleaned, and graded laboratory data as per Common Terminology Criteria for Adverse Events (CTCAE) version 5 for 22 commonly evaluated grade 3-4 adverse events (fatal events were not evaluated) with numerically based CTCAE definitions. Descriptive statistics tabulated adverse event frequencies. Adverse events ascertained by ExtractEHR were compared to manually reported adverse events for patients enrolled in two COG trials (AAML1031, NCT01371981; AALL0932, NCT02883049). Analyses were restricted to protocol-defined chemotherapy courses (induction I, induction II, intensification I, intensification II, and intensification III for acute myeloid leukaemia; induction, consolidation, interim maintenance, delayed intensification, and maintenance for acute lymphoblastic leukaemia).

FINDINGS: Laboratory adverse event data from 1077 patients (583 from Children's Healthcare of Atlanta, 200 from the Children's Hospital of Philadelphia, and 294 from the Texas Children's Hospital) who underwent 4611 courses (549 for acute myeloid leukaemia and 4062 for acute lymphoblastic leukaemia) were extracted, processed, and graded. Of the 166 patients with acute myeloid leukaemia, 86 (52%) were female, 80 (48%) were male, 96 (58%) were White, and 132 (80%) were non-Hispanic. Of the 911 patients with acute lymphoblastic leukaemia, 406 (45%) were female, 505 (55%) were male, 596 (65%) were White, and 641 (70%) were non-Hispanic. Patients with acute myeloid leukaemia had the most adverse events during induction I and intensification II. Hypokalaemia (one [17%] of six to 75 [48%] of 156 courses) and alanine aminotransferase (ALT) increased (13 [10%] of 134 to 27 [17%] of 156 courses) were the most prevalent non-haematological adverse events in patients with acute myeloid leukaemia, as identified by ExtractEHR. Patients with acute lymphoblastic leukaemia had the greatest number of adverse events during induction and maintenance (eight adverse events with prevalence ≥10%; induction and maintenance: anaemia, platelet count decreased, white blood cell count decreased, neutrophil count decreased, lymphocyte count decreased, ALT increased, and hypocalcaemia; induction: hypokalaemia; maintenance: aspartate aminotransferase [AST] increased and blood bilirubin increased), as identified by ExtractEHR. 187 (85%) of 220 total comparisons in 22 adverse events in four AAML1031 and six AALL0923 courses were substantially higher with ExtractEHR than COG-reported adverse event rates for adverse events with a prevalence of at least 2%.

INTERPRETATION: ExtractEHR is scalable and accurately defines laboratory adverse event rates for paediatric acute leukaemia; moreover, ExtractEHR seems to detect higher rates of laboratory adverse events than those reported in COG trials. These rates can be used for comparisons between therapies and to counsel patients treated on or off trials about the risks of chemotherapy. ExtractEHR-based adverse event ascertainment can improve reporting of laboratory adverse events in clinical trials.

FUNDING: US National Institutes of Health, St Baldrick's Foundation, and Alex's Lemonade Stand Foundation.

Pediatric acute myeloid leukemia (AML) is a devastating disease with a high risk of relapse. Current risk classification designates patients as high or low risk (LR) based on molecular features and therapy response. However, 30% of LR patients still suffer relapse, indicating a need for improvement in risk stratification. Cytokine levels, such as IL-6 and IL-10, have been shown to be prognostic in adult AML but have not been well studied in children. Previously, we reported elevated IL-6 levels in pediatric AML bone marrow to be associated with inferior prognosis. Here, we expanded our investigation to assess cytokine levels in diagnostic peripheral blood plasma (PBP) of pediatric AML patients and determined correlation with outcome. Diagnostic PBP was obtained from 80 patients with LR AML enrolled on the Children's Oncology Group AAML1031 study and normal PBP from 11 controls. Cytokine levels were measured and correlation with clinical outcome was assessed. IL-6, TNFα, MIP-3a, and IL-1β were significantly higher in AML patients versus controls when corrected by the Bonferroni method. Furthermore, elevated TNFα and IL-10 were significantly associated with inferior outcomes. Our data demonstrate that in diagnostic PBP of LR pediatric AML patients, certain cytokine levels are elevated as compared to healthy controls and that elevated TNFα and IL-10 are associated with inferior outcomes, supporting the idea that an abnormal inflammatory state may predict poor outcomes. Studies are needed to determine the mechanisms by which these cytokines impact survival, and to further evaluate their use as prognostic biomarkers in pediatric AML.

Risk stratification for acute myeloid leukemia (AML) uses molecular and cytogenetic abnormalities identified at diagnosis. Response to therapy informs risk, and morphology continues to be used more frequently than flow cytometry. Herein, the largest cohort of pediatric patients prospectively assessed for measurable residual disease (MRD) by flow cytometry (N = 784) is reported. The "difference from normal" (ΔN) technique was applied: 31% of all patients tested positive (AML range, 0.02% to 91%) after the first course of treatment on Children's Oncology Group study AAML0531. Detection of MRD following initial chemotherapy proved the strongest predicator of overall survival (OS) in univariable and multivariable analyses, and was predictive of relapse risk, disease-free survival, and treatment-related mortality. Clearance of MRD after a second round of chemotherapy did not improve survival. The morphologic definition of persistent disease (>15% AML) failed 27% of the time; those identified as MRD- had superior outcomes. Similarly, for patients not achieving morphologic remission (>5% blasts), 36% of patients were MRD- and had favorable outcomes compared with those who were MRD+ (P < .001); hence an increase in myeloid progenitor cells can be favorable when ΔN classifies them as phenotypically normal. Furthermore, ΔN reclassified 20% of patients in morphologic remission as having detectable MRD with comparable poor outcomes. Retrospective analysis using the relapse phenotype as a template demonstrated that 96% of MRD- patients had <0.02% of the relapse immunophenotype in their end of induction 1 marrow. Thus, the detection of abnormal myeloid progenitor cells by ΔN is both specific and sensitive, with a high predictive signal identifiable early in treatment. This trial was registered at www.clinicaltrials.gov as #NCT00372593.

The addition of the proteasome inhibitor (PI) bortezomib to standard chemotherapy (ADE: cytarabine [Ara-C], daunorubicin and etoposide,) did not improve overall outcome in the Children's Oncology Group AAML1031 phase 3 randomized clinical trial (AAML1031). Bortezomib prevents protein degradation, including RelA via the intracellular NF-kB pathway. In this study, we hypothesized that subgroups of pediatric AML patients benefitting from standard therapy plus bortezomib (ADEB) could be identified based on pre-treatment RelA expression and phosphorylation status. RelA-total and phosphorylation at serine 536 (RelA-pSer ) levels were measured in 483 patient samples using reverse phase protein array technology. In ADEB-treated patients, low-RelA-pSer was favorably prognostic when compared to high-RelA-pSer (3-yr overall survival (OS): 81% vs. 68%, p = 0.032; relapse risk (RR): 30% vs. 49%, p = 0.004). RR in low-RelA-pSer patients significantly decreased in ADEB compared to ADE (RR: 30% vs. 44%, p = 0.035). Correlation between RelA-pSer and 295 other assayed proteins identified a strong correlation with HSF1-pSer , another protein previously identified as modifying ADEB response. The combination of low-RelA-pSer and low-HSF1-pSer was a significant predictor of ADEB response (3-yr OS: 86% vs. 67%, p = 0.013). Thus, bortezomib may improve clinical outcome in a subgroup of AML patients identified by low-RelA-pSer and low-HSF1-pSer . This article is protected by copyright. All rights reserved.

<p>International Working Group (IWG) and European LeukemiaNet (ELN) response definitions are utilized to evaluate the efficacy of new agents for childhood acute myeloid leukemia (AML) for regulatory purposes. However, these criteria are not consistent with definitions used in pediatric AML trials or with standard pediatric practice to proceed with subsequent therapy cycles prior to IWG/ELN-defined count recovery. We retrospectively analyzed data from the two most recent Phase 3 pediatric AML clinical trials conducted by the Children's Oncology Group (COG) to assess the incidence, timing, and prognostic significance of count recovery following induction chemotherapy. Of the patients with fewer than 5% bone marrow blasts at the end of first induction, 21.5% of patients proceeded to a second induction cycle prior to achieving ANC ≥ 500 cells/μL and platelets ≥ 50,000 cells/μL, both well below the IWG/ELN thresholds of ANC &gt; 1000 cells/μL and platelets &gt; 100,000 cells/μL. In these two sequential childhood AML Phase 3 trials, neither ANC nor platelet recovery predicted survival. Intensification of treatment through the initiation of subsequent therapy cycles prior to attainment of IWG/ELN-defined CR is common practice in clinical trials for children with AML, suggesting that updated response definitions are needed for pediatric AML.</p>

<p>Pediatric acute myeloid leukemia (AML) remains a fatal disease for at least 30% of patients, stressing the need for improved therapies and better risk stratification. As proteins are the unifying feature of (epi)genetic and environmental alterations, and are often targeted by novel chemotherapeutic agents, we studied the proteomic landscape of pediatric AML. Protein expression and activation levels were measured in 500 bulk leukemic patient samples and 30 control CD34+ samples, using the reverse phase protein arrays with 296 strictly validated antibodies. The multi-step "MetaGalaxy" analysis methodology was applied and identified nine protein expression signatures (PrSIG), based on strong recurrent protein expression patterns. PrSIGs were associated with cytogenetics and mutational state, and with both favorable or unfavorable prognosis. Analysis based on treatment (i.e., ADE vs. ADE plus bortezomib (ADEB)) identified three PrSIGs that did better with ADEB vs. ADE. When PrSIGs were studied in the context of genetic subgroups, PrSIGs were independently prognostic after multivariate analysis, suggesting a potential value for proteomics in combination with current classification systems. Proteins with universally increased (n=7) or decreased (n=17) expression were observed across PrSIGs. Expression of certain proteins significantly differentially expressed from normal could be identified, forming a hypothetical platform for personalized medicine.</p>