Identification of regulators of polyploidization presents therapeutic targets for treatment of AMKL.

The mechanism by which cells decide to skip mitosis to become polyploid is largely undefined. Here we used a high-content image-based screen to identify small-molecule probes that induce polyploidization of megakaryocytic leukemia cells and serve as perturbagens to help understand this process. Our study implicates five networks of kinases that regulate the switch to polyploidy. Moreover, we find that dimethylfasudil (diMF, H-1152P) selectively increased polyploidization, mature cell-surface marker expression, and apoptosis of malignant megakaryocytes. An integrated target identification approach employing proteomic and shRNA screening revealed that a major target of diMF is Aurora kinase A (AURKA). We further find that MLN8237 (Alisertib), a selective inhibitor of AURKA, induced polyploidization and expression of mature megakaryocyte markers in acute megakaryocytic leukemia (AMKL) blasts and displayed potent anti-AMKL activity in vivo. Our findings provide a rationale to support clinical trials of MLN8237 and other inducers of polyploidization and differentiation in AMKL.

Heat shock factor 1 (HSF1-pSer326) predicts response to bortezomib-containing chemotherapy in pediatric AML: a COG report.

Bortezomib (BTZ) was recently evaluated in a randomized phase 3 clinical trial by the Children's Oncology Group (COG) that compared standard chemotherapy (cytarabine, daunorubicin, and etoposide [ADE]) vs standard therapy with BTZ (ADEB) for de novo pediatric acute myeloid leukemia (AML). Although the study concluded that BTZ did not improve outcome overall, we examined patient subgroups benefiting from BTZ-containing chemotherapy using proteomic analyses. The proteasome inhibitor BTZ disrupts protein homeostasis and activates cytoprotective heat shock responses. Total heat shock factor 1 (HSF1) and phosphorylated HSF1 (HSF1-pSer326) were measured in leukemic cells from 483 pediatric patients using reverse phase protein arrays. HSF1-pSer326 phosphorylation was significantly lower in pediatric AML compared with CD34+ nonmalignant cells. We identified a strong correlation between HSF1-pSer326 expression and BTZ sensitivity. BTZ significantly improved outcome of patients with low-HSF1-pSer326 with a 5-year event-free survival of 44% (ADE) vs 67% for low-HSF1-pSer326 treated with ADEB (P = .019). To determine the effect of HSF1 expression on BTZ potency in vitro, cell viability with HSF1 gene variants that mimicked phosphorylated (S326A) and nonphosphorylated (S326E) HSF1-pSer326 were examined. Those with increased HSF1 phosphorylation showed clear resistance to BTZ vs those with wild-type or reduced HSF1-phosphorylation. We hypothesize that HSF1-pSer326 expression could identify patients who benefit from BTZ-containing chemotherapy.

CEBPA-bZip mutations are associated with favorable prognosis in de novo AML: a report from the Children's Oncology Group.

Biallelic CEBPA mutations are associated with favorable outcomes in acute myeloid leukemia (AML). We evaluated the clinical and biologic implications of CEBPA-basic leucine zipper (CEBPA-bZip) mutations in children and young adults with newly diagnosed AML. CEBPA-bZip mutation status was determined in 2958 patients with AML enrolled on Children's Oncology Group trials (NCT00003790, NCT0007174, NCT00372593, NCT01379181). Next-generation sequencing (NGS) was performed in 1863 patients (107 with CEBPA mutations) to characterize the co-occurring mutations. CEBPA mutational status was correlated with disease characteristics and clinical outcomes. CEBPA-bZip mutations were identified in 160 (5.4%) of 2958 patients, with 132 (82.5%) harboring a second CEBPA mutation (CEBPA-double-mutated [CEBPA-dm]) and 28 (17.5%) had a single CEBPA-bZip only mutation. The clinical and laboratory features of the 2 CEBPA cohorts were very similar. Patients with CEBPA-dm and CEBPA-bZip experienced identical event-free survival (EFS) of 64% and similar overall survival (OS) of 81% and 89%, respectively (P = .259); this compared favorably to EFS of 46% and OS of 61% in patients with CEBPA-wild-type (CEBPA-WT) (both P < .001). Transcriptome analysis demonstrated similar expression profiles for patients with CEBPA-bZip and CEBPA-dm. Comprehensive NGS of patients with CEBPA mutations identified co-occurring CSF3R mutations in 13.1% of patients and GATA2 mutations in 21.5% of patients. Patients with dual CEBPA and CSF3R mutations had an EFS of 17% vs 63% for patients with CEBPA-mutant or CSF3R-WT (P < .001) with a corresponding relapse rate (RR) of 83% vs 22%, respectively (P < .001); GATA2 co-occurrence did not have an impact on outcome. CEBPA-bZip domain mutations are associated with favorable clinical outcomes, regardless of monoallelic or biallelic status. Co-occurring CSF3R and CEBPA mutations are associated with a high RR that nullifies the favorable prognostic impact of CEBPA mutations.

Comprehensive molecular and clinical characterization of NUP98 fusions in pediatric acute myeloid leukemia.

NUP98 fusions comprise a family of rare recurrent alterations in AML, associated with adverse outcomes. In order to define the underlying biology and clinical implications of this family of fusions, we performed comprehensive transcriptome, epigenome, and immunophenotypic profiling of 2,235 children and young adults with AML and identified 160 NUP98 rearrangements (7.2%), including 108 NUP98-NSD1 (4.8%), 32 NUP98-KDM5A (1.4%) and 20 NUP98-X cases (0.9%) with 13 different fusion partners. Fusion partners defined disease characteristics and biology; patients with NUP98-NSD1 or NUP98-KDM5A had distinct immunophenotypic, transcriptomic, and epigenomic profiles. Unlike the two most prevalent NUP98 fusions, NUP98-X variants are typically not cryptic. Furthermore, NUP98-X cases are associated with WT1 mutations, and have epigenomic profiles that resemble either NUP98-NSD1 or NUP98-KDM5A. Cooperating FLT3-ITD and WT1 mutations define NUP98-NSD1, and chromosome 13 aberrations are highly enriched in NUP98-KDM5A. Importantly, we demonstrate that NUP98 fusions portend dismal overall survival, with the noteworthy exception of patients bearing abnormal chromosome 13 (clinicaltrials gov. Identifiers: NCT00002798, NCT00070174, NCT00372593, NCT01371981).

Pathologic, cytogenetic, and molecular features of acute myeloid leukemia with megakaryocytic differentiation: A report from the Children's Oncology Group.

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.

Clinical relevance of proteomic profiling in de novo pediatric acute myeloid leukemia: a Children's Oncology Group study.

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 patients' samples and 30 control CD34+ cell samples, using reverse phase protein arrays with 296 strictly validated antibodies. The multistep MetaGalaxy analysis methodology was applied and identified nine protein expression signatures (PrSIG), based on strong recurrent protein expression patterns. PrSIG were associated with cytogenetics and mutational state, and with favorable or unfavorable prognosis. Analysis based on treatment (i.e., ADE vs. ADE plus bortezomib) identified three PrSIG that did better with ADE plus bortezomib than with ADE alone. When PrSIG were studied in the context of cytogenetic risk groups, PrSIG 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 PrSIG. Certain proteins significantly differentially expressed from normal could be identified, forming a hypothetical platform for personalized medicine.

Outcomes of intensification of induction chemotherapy for children with high-risk acute myeloid leukemia: A report from the Children's Oncology Group.

BACKGROUND: High-risk pediatric acute myeloid leukemia confers a poor prognosis, and alternative strategies are needed to improve outcomes. We hypothesized that intensifying induction on the AAML1031 clinical trial would improve outcomes compared to the predecessor trial AAML0531. METHODS: Patients on AAML0531 received cytarabine (1600 mg/m2 )/daunorubicin (150 mg/m2 )/etoposide (ADE) for induction II and patients on AAML1031 received mitoxantrone (48 mg/m2 )/cytarabine (8000 mg/m2 ) (MA). Stem cell transplant (SCT) conditioning included busulfan/cyclophosphamide on AAML0531, whereas AAML1031 used busulfan/fludarabine and liberalized donor eligibility. Patients were included in this analysis if they met high-risk criteria common to the two trials by cytogenics or poor disease response after induction I ADE. RESULTS: MA provided no benefit over ADE at: induction II response (complete response [CR]: 64% vs. 62%, p = .87; measurable residual disease [MRD]+: 57% vs. 46%, p = .34); or intensification I response (CR: 79% vs. 94%, p = .27; MRD+: 27% vs. 20%, p = 1.0). When considered with altered SCT approach, MA did not improve 5-year disease-free survival (24% ± 9% vs. 18% ± 15%, p = .63) or 5-year overall survival (35% ± 10% vs. 38% ± 18%, p = .66). MA was associated with slower neutrophil recovery (median 34 vs. 27 days, p = .007) and platelet recovery (median 29 vs. 24.5 days, p = .04) and longer hospital stay (32 vs. 28 days, p = .01) during induction II. CONCLUSION: Intensification of induction II did not improve treatment response or survival, but did increase toxicity and resource utilization. Alternative strategies are urgently needed to improve outcomes for pediatric patients with high-risk acute myeloid leukemia (trials registered at clinicaltrials.gov NCT01371981, NCT00372593).

MYOD1 as a prognostic indicator in rhabdomyosarcoma.

BACKGROUND/OBJECTIVES: Rhabdomyosarcoma (RMS) is characterized by the expression of the myogenic regulatory protein MYOD1. Histologic types include alveolar, embryonal (ERMS), and spindle cell sclerosing RMS (SRMS). SRMS harbors MYOD1 mutations in a subset of adult cases in association with poor prognosis. DESIGN/METHODS: To study the level of MYOD1 protein expression and its clinical significance, we have analyzed variable numbers of pediatric (<18 years of age) and adult (age range ≥18 to 35 years) ERMS and SRMS cases for presence or absence of MYOD1 immunoreactivity in correlation with clinical outcome and MYOD1 L122R mutations. RESULTS: Lack of MYOD1 immunoreactivity, identified in 23.8% of nonalveolar RMS (non-ARMS) cases, was more prevalent in SRMS (44%) than ERMS (17.2%) and was significantly associated with low overall survival and unfavorable tumor sites (p < .05). Lack of MYOD1 immunoreactivity was not associated with MYOD1 L122R mutations, which were identified in 3/37 (8%) cases including only two of 31 (6.5%) pediatric cases, one of 11 or 9% pediatric SRMS, and one case of infant ERMS. CONCLUSION: These studies highlight the prognostic role of MYOD1 in non-ARMS. Lack of MYOD1 immunoreactivity is associated with poor prognosis in ERMS and SRMS. MYOD1 gene mutations are generally infrequent in pediatric RMS. Although mutations are predominant in SRMS, they may exceptionally occur in infantile ERMS.

Mixed-phenotype acute leukemia: A cohort and consensus research strategy from the Children's Oncology Group Acute Leukemia of Ambiguous Lineage Task Force.

BACKGROUND: Optimal chemotherapy for treating mixed-phenotype acute leukemia (MPAL) and the role of hematopoietic stem cell transplantation (HSCT) remain uncertain. Major limitations in interpreting available data are MPAL's rarity and the use of definitions other than the currently widely accepted criteria: the World Health Organization 2016 (WHO2016) classification. METHODS: To assess the relative efficacy of chemotherapy types for treating pediatric MPAL, the Children's Oncology Group (COG) Acute Leukemia of Ambiguous Lineage Task Force assembled a retrospective cohort of centrally reviewed WHO2016 MPAL cases selected from banking studies for acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML). Patients were not treated in COG trials; treatment and outcome data were captured separately. The findings were then integrated with the available, mixed literature to develop a prospective trial in pediatric MPAL. RESULTS: The central review confirmed that 54 of 70 cases fulfilled WHO2016 criteria for MPAL. ALL induction regimens achieved remission in 72% of the cases (28 of 39), whereas AML regimens achieved remission in 69% (9 of 13). The 5-year event-free survival (EFS) and overall survival (OS) rates for the entire cohort were 72% ± 8% and 77% ± 7%, respectively. EFS and OS were 75% ± 13% and 84% ± 11%, respectively, for those receiving ALL chemotherapy alone without HSCT (n = 21). CONCLUSIONS: The results of the COG MPAL cohort and a literature review suggest that ALL chemotherapy without HSCT may be the preferred initial therapy. A prospective trial within the COG is proposed to investigate this approach; AML chemotherapy and/or HSCT will be reserved for those with treatment failure as assessed by minimal residual disease. Embedded biology studies will provide further insight into MPAL genomics.

Treatment of children with relapsed and refractory acute lymphoblastic leukemia with mitoxantrone, vincristine, pegaspargase, dexamethasone, and bortezomib.

BACKGROUND: The treatment of relapsed or refractory acute lymphoblastic leukemia (ALL) in children is challenging and new treatment options are needed. Bortezomib is a proteasome inhibitor with activity in pediatric acute lymphoblastic leukemia. Adding bortezomib to standard reinduction chemotherapy in relapsed and refractory pediatric ALL has produced very good response rates in prior studies. METHODS: We evaluated bortezomib in combination with reinduction therapy (ALL R3) in 10 children with relapsed or refractory ALL. Bortezomib (1.3 mg/m2 /dose) was administered to patients on days 1, 4, 8, and 11. In addition, patients received mitoxantrone, dexamethasone, pegaspargase, vincristine, and intrathecal methotrexate over 4 weeks. RESULTS: Of the 10 patients, eight (80%) achieved a complete remission (CR) or complete remission with incomplete recovery (CRi). Of the patients in CR, two had undetectable minimal residual disease by flow cytometry (<0.01%). Five patients were subsequently treated with a stem cell transplant. All eight patients that achieved CR or CRi eventually relapsed. One patient remains alive following treatment with tisagenlecleucel after relapse. Grade 3 or higher infections occurred in four out of 10 patients, and other toxicities commonly associated with bortezomib were not seen. CONCLUSIONS: In children with relapsed or refractory ALL, the addition of bortezomib to reinduction chemotherapy that includes mitoxantrone produces a complete response in the majority of cases and does not lead to excessive toxicity.

Genomic architecture and treatment outcome in pediatric acute myeloid leukemia: a Children's Oncology Group report.

Childhood acute myeloid leukemia (AML) is frequently characterized by chromosomal instability. Approximately 50% of patients have disease relapse, and novel prognostic markers are needed to improve risk stratification. We performed genome-wide genotyping in 446 pediatric patients with de novo AML enrolled in Children's Oncology Group (COG) studies AAML0531, AAML03P1, and CCG2961. Affymetrix and Illumina Omni 2.5 platforms were used to evaluate copy-number alterations (CNAs) and determine their associations with treatment outcome. Data from Affymetrix and Illumina studies were jointly analyzed with ASCAT and GISTIC software. An average of 1.14 somatically acquired CNAs per patient were observed. Novel reoccurring altered genomic regions were identified, and the presence of CNAs was found to be associated with decreased 3-year overall survival (OS), event-free survival (EFS), and relapse risk from the end of induction 1 (hazard ratio [HR], 1.7; 95% confidence interval [CI], 1.2-2.4; HR, 1.4; 95% CI, 1.0-1.8; and HR, 1.4; 95% CI, 1.0-2.0, respectively). Analyses by risk group demonstrated decreased OS and EFS in the standard-risk group only (HR, 1.9; 95% CI, 1.1-3.3 and HR, 1.7; 95% CI, 1.1-2.6, respectively). Additional studies are required to test the prognostic significance of CNA presence in disease relapse in patients with AML. COG studies AAML0531, AAML03P1, and CCG2961 were registered at www.clinicaltrials.gov as #NCT01407757, #NCT00070174, and #NCT00003790, respectively.

Improved outcomes for myeloid leukemia of Down syndrome: a report from the Children's Oncology Group AAML0431 trial.

Patients with myeloid leukemia of Down syndrome (ML-DS) have favorable event-free survival (EFS), but experience significant treatment-related morbidity and mortality. ML-DS blast cells ex vivo have increased sensitivity to cytarabine (araC) and daunorubicin, suggesting that optimizing drug dosing may improve outcomes while reducing toxicity. The Children's Oncology Group (COG) AAML0431 trial consisted of 4 cycles of induction and 2 cycles of intensification therapy based on the treatment schema of the previous COG A2971 trial with several modifications. High-dose araC (HD-araC) was used in the second induction cycle instead of the intensification cycle, and 1 of 4 daunorubicin-containing induction cycles was eliminated. For 204 eligible patients, 5-year EFS was 89.9% and overall survival (OS) was 93.0%. The 5-year OS for 17 patients with refractory/relapsed leukemia was 34.3%. We determined the clinical significance of minimal residual disease (MRD) levels as measured by flow cytometry on day 28 of induction I. MRD measurements, available for 146 of the 204 patients, were highly predictive of treatment outcome; 5-year disease-free survival for MRD-negative patients (n = 125) was 92.7% vs 76.2% for MRD-positive patients (n = 21) (log-rank P = .011). Our results indicated that earlier use of HD-araC led to better EFS and OS in AAML0431 than in past COG studies. A 25% reduction in the cumulative daunorubicin dose did not impact outcome. MRD, identified as a new prognostic factor for ML-DS patients, can be used for risk stratification in future clinical trials. This trial was registered at www.clinicaltrials.gov as #NCT00369317.

Risk Markers for Significant Bleeding and Thrombosis in Pediatric Acute Promyelocytic Leukemia; Report From the Children's Oncology Group Study AAML0631.

Acute promyelocytic leukemia (APL) is characterized by a heightened risk of coagulopathy with significant morbidity and mortality. Here we report our evaluation of presenting white blood cell (WBC) and the International Society on Thrombosis and Haemostasis (ISTH) disseminated intravascular coagulation (DIC) scoring system as markers for early death and nonlethal coagulopathy in pediatric APL. We evaluated 79 pediatric patients treated on a Children's Oncology Group phase III clinical trial. There were 4 early deaths and 13 nonlethal, clinically significant (grade III to IV) coagulopathy events during induction. Elevated presenting WBC was significantly associated with early death but not with both lethal and nonlethal coagulopathy events. An ISTH DIC score of ≥5 (the original ISTH criteria for overt DIC) was not associated with either early deaths or coagulopathy events. An ISTH DIC score threshold of 6, however, was significantly associated with early death (12% score ≥6 vs. 0% score <6) and with both lethal and nonlethal coagulopathy events (35% score ≥6 vs. 11% score <6). In pediatric APL patients, the presenting WBC is a marker for risk of early death. Although the ISTH score using a cutoff of ≥6 showed improved correlation with adverse coagulation events during induction, the sensitivity was only 70.6% (95% confidence interval, 44.0%-89.7%) and the specificity was 64.5% (95% confidence interval, 51.3%-76.3%). Thus, there is a strong need to identify other biomarkers that can predict APL-associated coagulopathy.

Genomics of primary chemoresistance and remission induction failure in paediatric and adult acute myeloid leukaemia.

Cure rates of children and adults with acute myeloid leukaemia (AML) remain unsatisfactory partly due to chemotherapy resistance. We investigated the genetic basis of AML in 107 primary cases by sequencing 670 genes mutated in haematological malignancies. SETBP1, ASXL1 and RELN mutations were significantly associated with primary chemoresistance. We identified genomic alterations not previously described in AML, together with distinct genes that were significantly overexpressed in therapy-resistant AML. Defined gene mutations were sufficient to explain primary induction failure in only a minority of cases. Thus, additional genetic or molecular mechanisms must cause primary chemoresistance in paediatric and adult AML.

Phenotype in combination with genotype improves outcome prediction in acute myeloid leukemia: a report from Children's Oncology Group protocol AAML0531.

Diagnostic biomarkers can be used to determine relapse risk in acute myeloid leukemia, and certain genetic aberrancies have prognostic relevance. A diagnostic immunophenotypic expression profile, which quantifies the amounts of distinct gene products, not just their presence or absence, was established in order to improve outcome prediction for patients with acute myeloid leukemia. The immunophenotypic expression profile, which defines each patient's leukemia as a location in 15-dimensional space, was generated for 769 patients enrolled in the Children's Oncology Group AAML0531 protocol. Unsupervised hierarchical clustering grouped patients with similar immunophenotypic expression profiles into eleven patient cohorts, demonstrating high associations among phenotype, genotype, morphology, and outcome. Of 95 patients with inv(16), 79% segregated in Cluster A. Of 109 patients with t(8;21), 92% segregated in Clusters A and B. Of 152 patients with 11q23 alterations, 78% segregated in Clusters D, E, F, G, or H. For both inv(16) and 11q23 abnormalities, differential phenotypic expression identified patient groups with different survival characteristics (P<0.05). Clinical outcome analysis revealed that Cluster B (predominantly t(8;21)) was associated with favorable outcome (P<0.001) and Clusters E, G, H, and K were associated with adverse outcomes (P<0.05). Multivariable regression analysis revealed that Clusters E, G, H, and K were independently associated with worse survival (P range <0.001 to 0.008). The Children's Oncology Group AAML0531 trial: clinicaltrials.gov Identifier: 00372593.

Central nervous system disease in pediatric acute myeloid leukemia: A report from the Children's Oncology Group.

BACKGROUND: The prognostic impact of central nervous system (CNS) involvement in children with acute myeloid leukemia (AML) has varied in past trials, and controversy exists over the degree of involvement requiring intensified CNS therapy. Two recent Children's Oncology Group protocols, AAML03P1 and AAML0531, directed additional intrathecal (IT) therapy to patients with CNS2 (≤5 white blood cell [WBC] with blasts) or CNS3 (>5 WBC with blasts or CNS symptoms) disease at diagnosis. METHODS: We examined disease characteristics and outcomes of the 1,344 patients on these protocols, 949 with CNS1 (no blasts), 217 with CNS2, and 178 with CNS3, with the latter two receiving additional IT therapy. RESULTS: Young age (P = 0.003), hyperleukocytosis (P < 0.001), and the presence of inversion 16 (P < 0.001) were the only factors more prevalent in patients with CNS2 or CNS3 disease. Complete remission at the end of induction (EOI) 2 was achieved less often in patients with CNS involvement (P < 0.001). From diagnosis, event-free survival (EFS) for patients with CNS involvement was significantly worse (P < 0.001), whereas overall survival (OS) was not (P = 0.16). From the EOI1, there was a higher relapse rate (RR) and worse disease-free survival (DFS), but less impact on OS (CNS1:DFS 58.9%, RR 34.1%, OS 69.3%; CNS2:DFS 53.2%, RR 40.9%, OS 74.7%; CNS3:DFS 45.2%, RR 48.8%, OS 60.8%; P = 0.006, P < 0.001, P = 0.045, respectively). Multivariable analysis showed that independently CNS2 and CNS3 status adversely affected RR and DFS. Traumatic diagnostic lumbar puncture was not associated with worse outcome. CONCLUSIONS: CNS leukemia confers greater relapse risk despite more aggressive locally directed therapy. Novel approaches need to be investigated in this group of patients.

Association between prolonged neutropenia and reduced relapse risk in pediatric AML: A report from the children's oncology group.

Objective was to describe the relationship between the number of sterile site infections and duration of neutropenia during the first four cycles of chemotherapy and the risk of recurrence and overall survival in children with newly diagnosed acute myeloid leukemia (AML). AAML0531 was a Children's Oncology Group randomized phase 3 clinical trial that included 1022 children with de novo AML. For this analysis, we focused on non-Down syndrome favorable and standard risk patients who completed at least 4 cycles of chemotherapy without recurrence or withdrawal during protocol therapy. Those receiving hematopoietic stem cell transplantation in first remission were excluded. Five hundred and sixty-nine patients were included; 274 (48.2%) were favorable risk. The median cumulative time with neutropenia between Induction II to completion of Intensification II was 96 (range 54-204) days. Number of sterile site infections did not influence the risk of relapse or overall survival. However, longer duration of neutropenia was associated with a lower risk of relapse (hazard ratio 0.81 per 20 days neutropenia, p = 0.007). Longer duration of neutropenia was associated with a reduced risk of relapse for children with favorable and standard risk AML. Toxicity may be influenced by pharmacogenomics suggesting that individualized chemotherapy dosing may be an effective strategy.

NUP98/NSD1 and FLT3/ITD coexpression is more prevalent in younger AML patients and leads to induction failure: a COG and SWOG report.

NUP98/NSD1 has recently been reported in association with poor outcome in acute myeloid leukemia (AML). Previous studies also observed a high overlap between NUP98/NSD1 and FLT3/ITD, raising the question as to whether the reported poor outcome is due to NUP98/NSD1 or caused by the co-occurrence of these 2 genetic lesions. We aimed to determine the prognostic significance of NUP98/NSD1 in the context of FLT3/ITD AML. A total of 1421 patients enrolled in 5 consecutive Children's Oncology Group/Children's Cancer Group and SWOG trials were evaluated. NUP98/NSD1 was found in 15% of FLT3/ITD and 7% of cytogenetically normal (CN)-AML. Those with dual FLT3/ITD and NUP98/NSD1 (82% of NUP98/NSD1 patients) had a complete remission rate of 27% vs 69% in FLT3/ITD without NUP98/NSD1 (P < .001). The corresponding 3-year overall survival was 31% vs 48% (P = .011), respectively. In CN-AML, patients with concomitant NUP98/NSD1 and FLT3/ITD had a worse outcome than those harboring NUP98/NSD1 only. In multivariate analysis, the dual NUP98/NSD1 and FLT3/ITD remained an independent predictor of poor outcome, and NUP98/NSD1 without FLT3/ITD lost its prognostic significance. Our study demonstrates that it is the interaction between NUP98/NSD1 and FLT3/ITD that determines the poor outcome of patients with NUP98/NSD1 disease.

miR-155 expression and correlation with clinical outcome in pediatric AML: A report from Children's Oncology Group.

BACKGROUND: Aberrant expression of microRNA-155 (miR-155) has been implicated in acute myeloid leukemia (AML) and associated with clinical outcome. PROCEDURE: We evaluated miR-155 expression in 198 children with normal karyotype AML (NK-AML) enrolled in Children's Oncology Group (COG) AML trial AAML0531 and correlated miR-155 expression levels with disease characteristics and clinical outcome. Patients were divided into quartiles (Q1-Q4) based on miR-155 expression level, and disease characteristics were then evaluated and correlated with miR-155 expression. RESULTS: MiR-155 expression varied over 4-log10-fold range relative to its expression in normal marrow with a median expression level of 0.825 (range 0.043-25.630) for the entire study cohort. Increasing miR-155 expression was highly associated with the presence of FLT3/ITD mutations (P < 0.001) and high-risk disease (P < 0.001) and inversely associated with standard-risk (P = 0.008) and low-risk disease (P = 0.041). Patients with highest miR-155 expression had a complete remission (CR) rate of 46% compared with 82% in low expressers (P < 0.001) with a correspondingly lower event-free (EFS) and overall survival (OS) (P < 0.001 and P = 0.002, respectively). In a multivariate model that included molecular risk factors, high miR-155 expression remained a significant independent predictor of OS (P = 0.022) and EFS (0.019). CONCLUSIONS: High miR-155 expression is an adverse prognostic factor in pediatric NK-AML patients. Specifically, high miR-155 expression not only correlates with FLT3/ITD mutation status and high-risk disease but it is also an independent predictor of worse EFS and OS.

Effectiveness of supportive care measures to reduce infections in pediatric AML: a report from the Children's Oncology Group.

Objective was to describe the effect of antibiotic and granulocyte colony-stimulating factor (G-CSF) prophylaxis and discharge policy on infection risk and nonrelapse-related mortality (NRM) during chemotherapy for children with acute myeloid leukemia. Patients were non-Down syndrome children enrolled on Children's Oncology Group (COG) trial AAML0531. We surveyed sites to determine institutional standards for systemic antibacterial, antifungal, and G-CSF prophylaxis, and mandatory hospitalization during neutropenia. COG institution survey response rate was 180 of 216 (83.3%). Of 1024 patients enrolled on AAML0531, 897 were non-Down patients from survey-responding institutions. In multiple regression, antibacterial prophylaxis reduced any sterile-site bacterial infection (incidence rate ratio [IRR] 0.85; 95% confidence interval [CI], 0.72-1.01; P = .058) and Gram-positive sterile-site infection (IRR 0.71; 95% CI, 0.57-0.90; P = .004). Prophylactic G-CSF reduced bacterial (IRR 0.79; 95% CI, 0.67-0.92; P = .004) and Clostridium difficile infections (CDIs; IRR 0.46; 95% CI, 0.25-0.84; P = .012). Mandatory hospitalization did not reduce bacterial/fungal infection or significantly reduce NRM but did increase CDI (IRR 1.96; 95% CI, 1.34-2.87; P < .001). Antibacterial and G-CSF prophylaxis reduced infection rates while mandatory hospitalization did not reduce infection or significantly affect NRM. This trial was registered at www.clinicaltrials.gov as #AAML0531.