Analysis of overweight/obese pediatric patients with acute myeloid leukemia: a report from the Japanese Pediatric Leukemia/Lymphoma Study Group AML-05 study

The dosage of chemotherapy drugs for overweight/obese children with acute myeloid leukemia (AML) has been empirically reduced based on ideal body weight (BW) in Japan to reduce the risk of adverse events. We investigated the associations between pre-therapeutic body mass index (BMI) and clinical outcomes among children with AML. A total of 280 children were divided into two groups based on the World Health Organization Child Growth Standards: a healthy-weight group (n = 254), and an overweight/obese group (n = 26). If BW exceeded 1.2 times the standard BW of Japanese children, the dosage of chemotherapy drugs was calculated using 1.2 times the standard BW. The dosage of chemotherapy drugs was reduced during at least one chemotherapy cycle in 24 of 26 patients (92.3%) in the overweight/obese group, compared with zero patients in the healthy-weight group. Overall/event-free survival, cumulative incidence of relapse, and treatment-related mortality (TRM) did not differ between the overweight/obese and healthy weight groups. However, the frequency of bacteremia was higher in the overweight/obese group (80.8 vs. 52.4%, P = 0.006). This indicates that TRM may increase when chemotherapy drug dosage is not corrected in overweight/obese patients. Drug reduction is a potential treatment strategy.

High IL2RA/CD25 expression is a prognostic stem cell biomarker for pediatric acute myeloid leukemia without a core-binding factor

CD25 is an aberrant marker expressed on the leukemic stem cell (LSC) surface and an immunotherapy target in acute myeloid leukemia (AML). However, the clinical prevalence and significance of CD25 expression in pediatric AML are unknown. High IL2RA/CD25 expression in pediatric AML showed a stem cell-like phenotype, and elevated CD25 expression was associated with lower overall survival (p < .001) and event-free survival (p < .001) in the Japanese Pediatric Leukemia/Lymphoma Study Group AML-05 study. This finding was reproduced in AML without a core-binding factor in the Children's Oncology Group study cohort. High CD25 expression has prognostic significance in pediatric AML.

Droplet digital polymerase chain reaction assay for the detection of the minor clone of KIT D816V in paediatric acute myeloid leukaemia especially showing RUNX1-RUNX1T1 transcripts

KIT D816V mutation within exon 17 has been particularly reported as one of the poor prognostic factors in pediatric acute myeloid leukemia (AML) with RUNX1-RUNX1T1. The exact frequency and the prognostic impact of KIT D816V minor clones at diagnosis were not examined. In this study, the minor clones were examined and the prognostic significance of KIT D816V mutation in pediatric patients was investigated. Consequently, 24 KIT D816V mutations (7.2%) in 335 pediatric patients were identified, and 12 of 24 were only detected via the digital droplet polymerase chain reaction method. All 12 patients were confined in core binding factor (CBF)-AML patients. The 5 year event-free survival of the patients with KIT D816V mutation was significantly inferior to those without KIT D816V mutation (44.1% [95% confidence interval (CI), 16.0%-69.4%] vs. 74.7% [95% CI, 63.0%-83.2%] P-value = 0.02, respectively). The 5 year overall survival was not different between the two groups (92.9% [95% CI, 59.0%-NA vs. 89.7% [95% CI, 69.6%-96.8%] P-value = 0.607, respectively). In this study, KIT D816V minor clones in patients with CBF-AML were confirmed and KIT D816V was considered as a risk factor for relapse in patients with RUNX1-RUNX1T1-positive AML.

Attempts to optimize postinduction treatment in childhood acute myeloid leukemia without core-binding factors: A report from the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG)

We previously reported that risk-stratified therapy and intensive postremission chemotherapy (PRC) contributed to the improved survival of childhood acute myeloid leukemia (AML) in the AML99 study, which led us to consider a reduction in the number of PRC courses with more restrictive indications for stem cell transplantation (SCT) in the successor AML-05 study. We here report the outcome of AML patients without core-binding factor mutation (non-CBF AML) in the AML-05 study. Two-hundred eighty-nine children (age < 18 years old) with non-CBF AML were eligible. Patients with unfavorable cytogenetics and/or poor bone marrow response to the first induction course were candidates for SCT in the AML-05 study. After two courses of induction, a further three courses of PRC were given in AML-05, while four courses were given in the AML99 study. The 3-year event-free survival (EFS) rate in the AML-05 study (46.7%, 95% CI: 40.6-52.6%) was comparable to that of non-CBF AML in the AML99 study (51.5%, 95% CI: 42.7-59.6%) (P = .16). However, the 3-year overall survival (OS) rate in the AML-05 study (62.9%, 95% CI: 56.3-68.8%) was slightly lower than that in the AML99 study (71.6%, 95% CI: 63.2-78.5%) (P = .060), mainly due to decreased remission induction rate and increased nonrelapsed mortality. In conclusion, reductions in the number of PRC courses from four to three, together with repetitive cycles of high-dose cytarabine, were acceptable for non-CBF childhood AML.

Fusion partner-specific mutation profiles and KRAS mutations as adverse prognostic factors in MLL-rearranged AML

Mixed-lineage leukemia (MLL) gene rearrangements are among the most frequent chromosomal abnormalities in acute myeloid leukemia (AML). MLL fusion patterns are associated with the patient's prognosis; however, their relationship with driver mutations is unclear. We conducted sequence analyses of 338 genes in pediatric patients with MLL-rearranged (MLL-r) AML (n = 56; JPLSG AML-05 study) alongside data from the TARGET study's pediatric cohorts with MLL-r AML (n = 104), non-MLL-r AML (n = 581), and adult MLL-r AML (n = 81). KRAS mutations were most frequent in pediatric patients with high-risk MLL fusions (MLL-MLLLT10, MLL-MLLT4, and MLL-MLLT1). Pediatric patients with MLL-r AML (n = 160) and a KRAS mutation (KRAS-MT) had a significantly worse prognosis than those without a KRAS mutation (KRAS-WT) (5-year event-free survival [EFS]: 51.8% vs 18.3%, P < .0001; 5-year overall survival [OS]: 67.3% vs 44.3%, P = .003). The adverse prognostic impact of KRAS mutations was confirmed in adult MLL-r AML. KRAS mutations were associated with adverse prognoses in pediatric patients with both high-risk (MLLT10+MLLT4+MLLT1; n = 60) and intermediate-to-low-risk (MLLT3+ELL+others; n = 100) MLL fusions. The prognosis did not differ significantly between patients with non-MLL-r AML with KRAS-WT or KRAS-MT. Multivariate analysis showed the presence of a KRAS mutation to be an independent prognostic factor for EFS (hazard ratio [HR], 2.21; 95% confidence interval [CI], 1.35-3.59; P = .002) and OS (HR, 1.85; 95% CI, 1.01-3.31; P = .045) in MLL-r AML. The mutation is a distinct adverse prognostic factor in MLL-r AML, regardless of risk subgroup, and is potentially useful for accurate treatment stratification. This trial was registered at the UMIN (University Hospital Medical Information Network) Clinical Trials Registry (UMIN-CTR; http://www.umin.ac.jp/ctr/index.htm) as #UMIN000000511.

Predisposition to prolonged neutropenia after chemotherapy for paediatric acute myeloid leukaemia is associated with better prognosis in the Japanese Paediatric Leukaemia/Lymphoma Study Group AML-05 study

The variability in myelosuppression after chemotherapy for acute myeloid leukaemia (AML) can affect its prognosis; however, the underlying mechanism remains controversial. In the Japanese Paediatric Leukaemia/Lymphoma Study Group AML-05 study, we showed that prolonged neutropenia was associated with high overall survival (P = 0·011) and low frequency of relapse (P = 0·042) in patients without granulocyte-colony stimulating factor (G-CSF) who completed the indicated treatment protocol. Our data indicate that predisposition to prolonged neutropenia after chemotherapy is correlated with a better outcome of AML treatment. Our results promote the usage of individualised drug dosing strategies to improve the therapeutic outcome in AML patients.

Patients aged less than 3 years with acute myeloid leukaemia characterize a molecularly and clinically distinct subgroup

Although infants (age <1 year) with acute myeloid leukaemia (AML) have unique characteristics and are vulnerable to chemotherapy, children aged 1-2 years with AML may have characteristics similar to that of infants. Thus, we analysed 723 paediatric AML patients treated on the Japanese AML99 and AML-05 trials to identify characteristics of younger children. We identified patients aged <3 years (the younger group) as a distinct subgroup. KMT2A-rearrangement (KMT2A-R), CBFA2T3-GLIS2, CBFB-MYH11 and NUP98-KDM5A were frequently found in the younger group. Prognostic analyses revealed poor 5-year overall survival (OS), event-free survival (EFS) and cumulative incidence of relapse (CIR) in patients with CBFA2T3-GLIS2 (42%, 17% and 83%, respectively) and those with NUP98-KDM5A (33%, 17% and 83%, respectively). Additionally, we identified KMT2A-R and CBFB-MYH11 as age-specific prognostic markers. Regarding KMT2A-R, the younger group had significantly better OS, EFS and CIR than the older group (aged 3 to <18 years) (P = 0·023, 0·011 and <0·001, respectively). Conversely, concerning CBFB-MYH11, the younger group had significantly poor EFS and CIR than the older group (each P < 0·001), suggesting that certain molecular markers are linked to different prognoses according to age. Therefore, we characterized patients <3 years as a distinct subgroup of paediatric AML.

Retrospective analysis of children with high-risk acute myeloid leukemia who underwent allogeneic hematopoietic stem cell transplantation following complete remission with initial induction chemotherapy in the AML-05 clinical trial

In the AML-05 clinical trial conducted by the Japanese Pediatric Leukemia/Lymphoma Group from 2006 to 2010, children with high-risk acute myeloid leukemia (HR AML) received allogeneic hematopoietic stem cell transplantation (allo-HSCT) at first complete remission (CR1). The aim of this study was to investigate the impact of allo-HSCT on the outcome of HR AML. Patients with either monosomy 7, 5q-, t(16;21), Ph1, FLT3-ITD, or induction failure after the first course of chemotherapy were eligible for transplant. Of 53 children with HR AML, 51 received allo-HSCT-45 in CR1, five in CR2, and one with non-CR. t(8;21), t(9;11), and t(16;21) abnormalities were identified in eight, five, and four patients, respectively. The stem cell sources varied-bone marrow in 30 patients, peripheral blood in three, and cord blood in 18. The median follow-up was 62 months. The overall survival (OS) rates at 3 years were 73% and 25% for patients who received transplant at CR1 and ≥CR2, respectively. Multivariable analysis showed that patients with chronic graft-versus-host disease (cGVHD) had better OS. This study supports that allo-HSCT is a suitable treatment for HR AML in CR1. The favorable outcome associated with cGVHD indicates that a graft-versus-leukemia effect might be occurring.

Clinical and biological features of paediatric acute myeloid leukaemia (AML) with primary induction failure in the Japanese Paediatric Leukaemia/Lymphoma Study Group AML-05 study

The prognosis of paediatric acute myeloid leukaemia (AML) with primary induction failure (PIF) is extremely poor, and effective treatment strategies have not been established. We investigated the clinical and biological features of paediatric AML patients with PIF registered to the Japanese Paediatric Leukaemia/Lymphoma Study Group AML-05 study. The 3-year overall survival rate of the 41 PIF patients was 19.0%. High leucocyte count, M7 morphology, and unfavourable genetic aberrations, such as FLT3-internal tandem duplication, NUP98-NSD1 and high MECOM or PRDM16 expression, were risk factors for PIF. More effective treatment strategies based on leukaemia biology need to be urgently explored.

1201. A Prolonged Multispecies Outbreak of Carbapenemase-Producing Enterobacteriaceae Due to Transmissible Plasmid With Carbapenemase Gene

Background

In 2010, a multispecies outbreak of IMP type carbapenemase-producing Enterobacteriaceae (IMP-CPE) occurred at a large acute care hospital in Japan. The outbreak continued for years involving more than 100 patients mainly in surgical wards.

Methods

Because of the long period of the outbreak, investigation were focused on hospitalized patients whose clinical samples were positive for IMP-CPE between July 2013 and March 2014. A case–control study was conducted for cases who underwent abdominal surgery with controls from whom meropenem-susceptible Enterobacteriaceae were isolated. Pulsed-field gel electrophoresis (PFGE) was used for molecular typing. To evaluate genetic relationship among IMP-CPE isolates of different species, plasmid analysis using S1 nuclease to separate plasmid and chromosomal DNA followed by plasmid DNA extraction and whole-genome sequencing (WGS) was conducted.

Results

During the study period, 22 cases were identified and 22 IMP-CPE isolates which consisted of eight Escherichia coli, five Klebsiella oxytoca, five Enterobacter cloacae, three Klebsiella pneumoniae and one Enterobacter aerogenes were obtained. All five isolates of K. oxytoca had similar PFGE profiles which suggested clonal transmission. However, PFGE profiles of E. coli, E. cloacae and K. pneumoniae isolates were diverse. Plasmid analysis revealed that all 22 isolates shared ca. 50 kb IncN plasmid with bla_IMP-6 which implies interspecies transmission of it The case–control study which adjusted by days of hospitalization with 11 cases and 24 controls revealed that pancreato-duodenectomy (adjusted odds ratio (aOR) = 6.4, 95% confidence interval (CI) 1.3–32.4) and enteric fistula (aOR = 8.0, 95% CI 1.5–41.9) were associated with IMP-CPE acquisition. Use of endoscopy within the past six months was not associated with IMP-CPE (aOR = 0.8 95% CI 0.2–4.2). With a bundled infection control with Osaka City Public Health Office, the outbreak was contained in July 2016.

Conclusion

Dissemination of carbapenemase gene by transmissible plasmid can play a critical role to complicate epidemiology of CPE outbreak and made it difficult to control. Plasmid analysis using WGS technology is a promising tool to untangle it.

Disclosures

All authors: No reported disclosures.

Monitoring of fusion gene transcripts to predict relapse in pediatric acute myeloid leukemia

BACKGROUND

In acute myeloid leukemia (AML), accurate detection of minimal residual disease (MRD) enables better risk-stratified therapy. There are few studies, however, on the monitoring of multiple fusion transcripts and evaluation of their accuracy as indicators of MRD at multiple time points.

METHODS

We retrospectively examined RNA obtained from 82 pediatric AML patients enrolled in the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) AML-05 study. The expression of six important fusion transcripts (AML1(RUNX1)-ETO, CBFB-MYH11, MLL(KMT2A)-AF9, MLL-ELL, MLL-AF6, and FUS-ERG) was analyzed at five time points 30-40 days apart following diagnosis.

RESULTS

In patients with AML1-ETO (n = 36 at time point 5), all six patients with >3,000 copies and four of 30 patients with ≤3,000 copies relapsed. AML1-ETO transcripts persisted during treatment even in patients without relapse, as well as CBFB-MYH11 transcripts. In contrast, in patients with MLL-AF9 (n = 9 at time point 5), two patients were positive for MLL-AF9 expression (>50 copies) and both relapsed. Only one of seven MLL-AF9-negative patients relapsed. In the AML1-ETO group, MRD-positive patients (>3,000 copies at time point 5) had significantly lower relapse-free survival (RFS; P < 0.0001) and overall survival (OS; P = 0.009) than MRD-negative patients. Similarly, in the MLL-AF9 group, MRD-positive patients (>50 copies at time point 5) had significantly lower RFS (P = 0.002) and OS (P = 0.002) than MRD-negative patients.

CONCLUSIONS

Detection of MLL-AF9 transcripts on real-time quantitative polymerase chain reaction is a promising marker of relapse in pediatric AML. In contrast, the clinical utility of detecting AML1-ETO and CBFB-MYH11 expression is limited, although higher AML1-ETO expression can be a potential predictor of relapse when assessed according to an optimal threshold.

Multiplex fusion gene testing in pediatric acute myeloid leukemia

BACKGROUND

Gene abnormalities, particularly chromosome rearrangements generating gene fusion, are associated with clinical characteristics and prognosis in pediatric acute myeloid leukemia (AML). Karyotyping is generally performed to enable risk stratification, but the results are not always consistent with those of reverse transcription-polymerase chain reaction (RT-PCR), and more accurate and rapid methods are required.

METHODS

A total of 487 samples from de novo AML patients enrolled in the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG) AML-05 study (n = 448), and from acute promyelocytic leukemia (APL) patients enrolled in the JPLSG AML-P05 study (n = 39) were available for this investigation. Multiplex quantitative RT-PCR was performed to detect eight important fusion genes: AML1(RUNX1)-ETO(RUNX1T1), CBFB-MYH11, MLL(KMT2A)-AF9(MLLT3), MLL-ELL, MLL-AF6(MLLT4), FUS(TLS)-ERG, NUP98-HOXA9, and PML-RARA.

RESULTS

Fusion genes were detected in 207 (46.2%) of the 448 AML-05 patient samples. After exclusion of two samples with PML-RARA, no chromosomal abnormalities were identified on karyotyping in 19 of 205 patients (9.3%) positive for fusion genes on RT-PCR. Fusion genes were confirmed on fluorescence in situ hybridization (FISH) in 11 of these 19 patients. In contrast, fusion genes were detected in 37 of 39 patients (94.9%) from the AML-P05 study, and 33 of these results were consistent with the karyotyping. There were discrepancies in four patients (10.8%), three with normal karyotypes and one in whom karyotyping was not possible. All four of these patients were PML-RARA positive on FISH.

CONCLUSIONS

Multiplex quantitative RT-PCR-based fusion gene screening may be effective for diagnosis of pediatric AML.

ASXL2 mutations are frequently found in pediatric AML patients with t(8;21)/ RUNX1-RUNX1T1 and associated with a better prognosis

ASXL2 is an epigenetic regulator involved in polycomb repressive complex regulation or recruitment. Clinical features of pediatric acute myeloid leukemia (AML) patients with ASXL2 mutations remain unclear. Thus, we investigated frequencies of ASXL1 and ASXL2 mutations, clinical features of patients with these mutations, correlations of these mutations with other genetic alterations including BCOR/BCORL1 and cohesin complex component genes, and prognostic impact of these mutations in 369 pediatric patients with de novo AML (0-17 years). We identified 9 (2.4%) ASXL1 and 17 (4.6%) ASXL2 mutations in 25 patients. These mutations were more common in patients with t(8;21)(q22;q22)/RUNX1-RUNX1T1 (ASXL1, 6/9, 67%, P = 0.02; ASXL2, 10/17, 59%, P = 0.01). Among these 25 patients, 4 (27%) of 15 patients with t(8;21) and 6 (60%) of 10 patients without t(8;21) relapsed. However, most patients with relapse were rescued using stem cell transplantation irrespective of t(8;21). The overall survival (OS) and event-free survival (EFS) rates showed no differences among pediatric AML patients with t(8;21) and ASXL1 or ASXL2 mutations and ASXL wild-type (5-year OS, 75% vs. 100% vs. 91% and 5-year EFS, 67% vs. 80% vs. 67%). In 106 patients with t(8;21) AML, the coexistence of mutations in tyrosine kinase pathways and chromatin modifiers and/or cohesin complex component genes had no effect on prognosis. These results suggest that ASXL1 and ASXL2 mutations play key roles as cooperating mutations that induce leukemogenesis, particularly in pediatric AML patients with t(8;21), and these mutations might be associated with a better prognosis than that reported previously.

CXCR4 Overexpression is a Poor Prognostic Factor in Pediatric Acute Myeloid Leukemia With Low Risk: A Report From the Japanese Pediatric Leukemia/Lymphoma Study Group

BACKGROUND

Overexpression of CXC chemokine receptor 4 (CXCR4+) is a poor prognostic factor in adult acute myeloid leukemia (AML); however, its prognostic significance in pediatric AML is unclear.

PROCEDURE

This retrospective study examined the prognostic significance of CXCR4+ in pediatric AML patients enrolled in the Japanese Pediatric Leukemia/Lymphoma Study Group AML-05 study.

RESULTS

In the total cohort (n = 248), no significant differences were observed between CXCR4+ patients (n = 81) and CXCR4- patients (n = 167) in terms of 3-year overall survival (OS) (69.4% vs. 75.2%, P = 0.44). However, there was a significant difference in 3-year OS between CXCR4+ and CXCR4- patients in the low-risk (LR) group (n = 93; 79.2% vs. 98.3%, P = 0.007). CXCR4+ patients in the t(8;21) AML without KIT mutation group had a significantly worse 3-year OS than CXCR4- patients (n = 44; 76.1% vs. 100.0%, P = 0.01). Multivariate Cox regression analysis identified CXCR4+ as a poor prognostic factor for OS in LR AML patients (hazard ratio, 11.47; P = 0.01). Consistent with the data for survival analysis, CXCR4+ patients in the t(8;21) AML group had a higher incidence of splenomegaly than CXCR4- patients (25.9% vs. 5.9%, P = 0.03).

CONCLUSIONS

These results suggest that CXCR4+ is a poor prognostic factor for LR patients, particularly t(8;21) patients without KIT mutation. The poor outcome was only applicable to OS, not relapse-free survival (RFS); thus, CXCR4+ may be associated with a poor prognosis after recurrence. Intensive therapy, including administration of CXCR4 antagonists, may be promising for pediatric AML patients with LR.

Whole-exome sequencing reveals the spectrum of gene mutations and the clonal evolution patterns in paediatric acute myeloid leukaemia

Acute myeloid leukaemia (AML) is a molecularly and clinically heterogeneous disease. Targeted sequencing efforts have identified several mutations with diagnostic and prognostic values in KIT, NPM1, CEBPA and FLT3 in both adult and paediatric AML. In addition, massively parallel sequencing enabled the discovery of recurrent mutations (i.e. IDH1/2 and DNMT3A) in adult AML. In this study, whole-exome sequencing (WES) of 22 paediatric AML patients revealed mutations in components of the cohesin complex (RAD21 and SMC3), BCORL1 and ASXL2 in addition to previously known gene mutations. We also revealed intratumoural heterogeneities in many patients, implicating multiple clonal evolution events in the development of AML. Furthermore, targeted deep sequencing in 182 paediatric AML patients identified three major categories of recurrently mutated genes: cohesion complex genes [STAG2, RAD21 and SMC3 in 17 patients (8·3%)], epigenetic regulators [ASXL1/ASXL2 in 17 patients (8·3%), BCOR/BCORL1 in 7 patients (3·4%)] and signalling molecules. We also performed WES in four patients with relapsed AML. Relapsed AML evolved from one of the subclones at the initial phase and was accompanied by many additional mutations, including common driver mutations that were absent or existed only with lower allele frequency in the diagnostic samples, indicating a multistep process causing leukaemia recurrence.

Preserved High Probability of Overall Survival with Significant Reduction of Chemotherapy for Myeloid Leukemia in Down Syndrome: A Nationwide Prospective Study in Japan

BACKGROUND

On the basis of results of previous Japanese trials for myeloid leukemia in Down syndrome (ML-DS), the efficacy of risk-oriented therapy was evaluated in the Japanese Pediatric Leukemia/Lymphoma Study Group AML-D05 study.

PROCEDURE

All patients received induction chemotherapy that consisted of pirarubicin, intermediate-dose cytarabine, and etoposide. Patients who achieved complete remission (CR) after initial induction therapy were stratified to the standard risk (SR) group and received four courses of reduced-dose intensification therapy. Patients who did not achieve CR were stratified to the high risk (HR) group and received intensified therapy that consisted of continuous or high-dose cytarabine.

RESULTS

A total of 72 patients were eligible and evaluated. One patient died of sepsis during initial induction therapy. Sixty-nine patients were stratified to SR and two patients to HR. No therapy-related deaths were observed during intensification therapy. The 3-year event-free and overall survival rates were 83.3% ± 4.4% and 87.5% ± 3.9%, respectively. Age at diagnosis less than 2 years was a significant favorable prognostic factor for risk of relapse (P = 0.009).

CONCLUSIONS

The attempt of risk-oriented prospective study for ML-DS was unsuccessful, but despite the dose reduction of chemotherapeutic agents, the overall outcome was good, and further dose reduction might be possible for specific subgroups.

High PRDM16 expression identifies a prognostic subgroup of pediatric acute myeloid leukaemia correlated to FLT3-ITD, KMT2A-PTD, and NUP98-NSD1: the results of the Japanese Paediatric Leukaemia/Lymphoma Study Group AML-05 trial

Recent reports described the NUP98-NSD1 fusion as an adverse prognostic marker for acute myeloid leukaemia (AML) and PRDM16 (also known as MEL1) as the representative overexpressed gene in patients harbouring NUP98-NSD1 fusion. PRDM16 gene expression levels were measured via real-time polymerase chain reaction in 369 paediatric patients with de novo AML, of whom 84 (23%) exhibited PRDM16 overexpression (PRDM16/ABL1 ratio ≥0·010). The frequencies of patients with high or low PRDM16 expression differed widely with respect to each genetic alteration, as follows: t(8;21), 4% vs. 96%, P < 0·001; inv(16), 0% vs. 100%, P < 0·001; KMT2A (also termed MLL)- partial tandem duplication, 100% vs. 0%, P < 0·001; NUP98-NSD1, 100% vs. 0%, P < 0·001. The overall survival (OS) and event-free survival (EFS) among PRDM16-overexpressing patients were significantly worse than in patients with low PRDM16 expression (3-year OS: 51% vs. 81%, P < 0·001, 3-year EFS: 32% vs. 64%, P < 0·001) irrespective of other cytogenetic alterations except for NPM1. PRDM16 gene expression was particularly useful for stratifying FLT3-internal tandem duplication-positive AML patients (3-year OS: high = 30% vs. low = 70%, P < 0·001). PRDM16 overexpression was highly recurrent in de novo paediatric AML patients with high/intermediate-risk cytogenetic profiles and was independently associated with an adverse outcome.

Clinical Impact of Additional Cytogenetic Aberrations, cKIT and RAS Mutations, and Treatment Elements in Pediatric t(8;21)-AML: Results From an International Retrospective Study by the International Berlin-Frankfurt-Münster Study Group

PURPOSE

This retrospective cohort study aimed to determine the predictive relevance of clinical characteristics, additional cytogenetic aberrations, and cKIT and RAS mutations, as well as to evaluate whether specific treatment elements were associated with outcomes in pediatric t(8;21)-positive patients with acute myeloid leukemia (AML).

PATIENTS AND METHODS

Karyotypes of 916 pediatric patients with t(8;21)-AML were reviewed for the presence of additional cytogenetic aberrations, and 228 samples were screened for presence of cKIT and RAS mutations. Multivariable regression models were used to assess the relevance of anthracyclines, cytarabine, and etoposide during induction and overall treatment. End points were the probability of achieving complete remission, cumulative incidence of relapse (CIR), probability of event-free survival, and probability of overall survival.

RESULTS

Of 838 patients included in final analyses, 92% achieved complete remission. The 5-year overall survival, event-free survival, and CIR were 74%, 58%, and 26%, respectively. cKIT mutations and RAS mutations were not significantly associated with outcome. Patients with deletions of chromosome arm 9q [del(9q); n = 104] had a lower probability of complete remission (P = .01). Gain of chromosome 4 (+4; n = 21) was associated with inferior CIR and survival (P < .01). Anthracycline doses greater than 150 mg/m(2) and etoposide doses greater than 500 mg/m(2) in the first induction course and high-dose cytarabine 3 g/m(2) during induction were associated with better outcomes on various end points. Cumulative doses of cytarabine greater than 30 g/m(2) and etoposide greater than 1,500 mg/m(2) were associated with lower CIR rates and better probability of event-free survival.

CONCLUSION

Pediatric patients with t(8;21)-AML and additional del(9q) or additional +4 might not be considered at good risk. Patients with t(8;21)-AML likely benefit from protocols that have high doses of anthracyclines, etoposide, and cytarabine during induction, as well as from protocols comprising cumulative high doses of cytarabine and etoposide.

Respiratory syncytial virus infection in infants with acute leukemia: a retrospective survey of the Japanese Pediatric Leukemia/Lymphoma Study Group

Respiratory syncytial virus (RSV) can cause life-threatening complications of lower respiratory tract infection (LRTI) in young children with malignancies, but reports remain limited. We performed a retrospective nationwide survey to clarify the current status of RSV disease among infants with hematological malignancies. Clinical course, treatment, and outcome of patients with hematological malignancies who suffered from RSV infections at the age of <24 months during anti-tumor therapy from April 2006 to March 2009 were investigated by sending a questionnaire to all member institutions of the Japanese Pediatric Leukemia/Lymphoma Study Group (JPLSG). Twelve patients with acute leukemia were identified as having experienced RSV disease. The primary diseases were acute myeloid leukemia (n = 8) and acute lymphoblastic leukemia (n = 4). RSV infection occurred pre- or during induction therapy (n = 8) and during consolidation therapy (n = 4). Eight patients developed LRTI, four of whom had severe pneumonia or acute respiratory distress syndrome; these four patients died despite receiving intensive care. In our survey, the prognosis of RSV disease in pediatric hematological malignancies was poor, and progression of LRTI in particular was associated with high mortality. In the absence of RSV-specific therapy, effective prevention and treatment strategies for severe RSV disease must be investigated.

CSF3R and CALR mutations in paediatric myeloid disorders and the association of CSF3R mutations with translocations, including t(8; 21)

Mutations in the colony-stimulating factor 3 receptor (CSF3R) and calreticulin (CALR) genes have been reported in a proportion of adults with myeloproliferative disease. However, little is known about CSF3R or CALR mutations in paediatric myeloid disorders. We analysed CSF3R exons 14 and 17, and CALR exon 9, using direct sequencing in samples of paediatric acute myeloid leukaemia (AML; n = 521), juvenile myelomonocytic leukaemia (JMML; n = 40), myelodysplastic syndrome (MDS; n = 20) and essential thrombocythaemia (ET; n = 21). CSF3R mutations were found in 10 (1.2%) of 521 patients with AML; two in exon 14 (both missense mutations resulting in p.T618I) and eight in exon 17 (three frameshift mutations: p.S715X, p.Q774R, and p.S783Q; and five novel missense mutations: p.Q754K, p.R769H, p.L777F, p.T781I, and S795R). All of the patients with mutations in CSF3R exon 17 had chromosomal translocations, including four with t(8;21). At the time of reporting, seven of these ten patients are alive; three have died, due to side effects of chemotherapy. No CSF3R mutations were found in cases of MDS, JMML or ET. The only mutation found in the CALR gene was a frameshift (p.L367 fs) in one ET patient. We discuss the potential impact of these findings for the leukaemogenesis and clinical features of paediatric myeloid disorders.

Prognostic implications of CEBPA mutations in pediatric acute myeloid leukemia: a report from the Japanese Pediatric Leukemia/Lymphoma Study Group

CCAAT/enhancer-binding protein alpha (CEBPA) mutations are a favorable prognostic factor in adult acute myeloid leukemia (AML) patients; however, few studies have examined their significance in pediatric AML patients. Here we examined the CEBPA mutation status and clinical outcomes of pediatric AML patients treated in the AML-05 study. We found that 47 (14.9%) of the 315 evaluable patients harbored mutations in CEBPA; 26 cases (8.3%) harbored a single mutation (CEBPA-single) and 21 (6.7%) harbored double or triple mutations (CEBPA-double). After excluding core-binding factor-AML cases, patients harboring CEBPA mutations showed better overall survival (OS; P=0.048), but not event-free survival (EFS; P=0.051), than wild-type patients. Multivariate analysis identified CEBPA-single and CEBPA-double as independent favorable prognostic factors for EFS in the total cohort (hazard ratio (HR): 0.47 and 0.33; P=0.02 and 0.01, respectively). CEBPA-double was also an independent favorable prognostic factor for OS (HR: 0.30; P=0.04). CEBPA-double remained an independent favorable factor for EFS (HR: 0.28; P=0.04) in the normal karyotype cohort. These results suggest that CEBPA mutations, particularly CEBPA-double, are an independent favorable prognostic factor in pediatric AML patients, which will have important implications for risk-stratified therapy.

Acute myeloid leukaemia with myelodysplastic features in children: a report of Japanese Paediatric Leukaemia/Lymphoma Study Group

The clinical characteristics and prognostic relevance of acute myeloid leukaemia (AML) with myelodysplastic features remains to be clarified in children. We prospectively examined 443 newly diagnosed patients in a multicentre clinical trial for paediatric de novo AML, and found 'AML with myelodysplasia-related changes' (AML-MRC) according to the 2008 World Health Organization classification in 93 (21·0%), in whom 59 were diagnosed from myelodysplasia-related cytogenetics alone, 28 from multilineage dysplasia alone and six from a combination of both. Compared with 111 patients with 'AML, not otherwise specified' (AML-NOS), patients with 'AML-MRC' presented at a younger age, with a lower white blood cell count, higher incidence of 20-30% bone marrow blasts, unfavourable cytogenetics and a lower frequency of Fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD), NPM1 and CEBPA mutations. Complete remission rate and 3-year probability of event-free survival were significantly worse in 'AML-MRC' patients (67·7 vs. 85·6%, P < 0·01, 37·1% vs. 53·8%, P = 0·02, respectively), but 3-year overall survival and relapse-free survival were comparable with 'AML-NOS' patients. By multivariate analysis, FLT3-ITD was solely associated with worse overall survival. These results support the distinctive features of the category 'AML-MRC' even in children.

Outcome of children with relapsed acute myeloid leukemia following initial therapy under the AML99 protocol

The outcomes of children with relapsed acute myeloid leukemia (AML) are known to be poor, but remain obscure. We retrospectively analyzed 71 patients who had relapsed following first-line treatment under the AML99 protocol. We investigated the time and site of recurrence, response to re-induction therapy, and performance of hematopoietic stem cell transplantation (HSCT) in relapsed cases, and performed a multivariate analysis to identify prognostic factors. The 5-year overall-survival (OS) rate after relapse was 37 %. Of 71 patients, three died without any anti-leukemic therapy and two underwent allogeneic HSCT. The remaining 66 patients received re-induction chemotherapy, and 33 (50 %) achieved second CR (CR2). Twenty-two of 25 (88 %) late relapse patients and 11 of 41 (27 %) early relapse patients achieved CR2 (P < 0.001). Twenty-nine CR2 cases and 35 non-CR2 cases underwent allogeneic HSCT. The 5-year OS rate was significantly higher in patients who underwent HSCT in CR2 than those in non-CR2 (66 vs. 17 %, P < 0.000001). Multivariate analysis indicated that early relapse (P < 0.05) and the positivity of the FMS-like tyrosine kinase 3--internal tandem duplication (P < 0.05) were adverse prognostic factors for survival. In conclusion, the etiology of relapsed pediatric AML needs to be elucidated and effective chemotherapy should be administered to obtain CR2.

WT1 mutation in pediatric patients with acute myeloid leukemia: a report from the Japanese Childhood AML Cooperative Study Group

Mutations in Wilms tumor 1 (WT1) have been reported in 10-22 % of patients with cytogenetically normal acute myeloid leukemia (CN-AML), but the prognostic implications of these abnormalities have not been clarified in either adults or children. One hundred and fifty-seven pediatric AML patients were analyzed for WT1 mutations around hotspots at exons 7 and 9; however, amplification of the WT1 gene by the reverse transcriptase-polymerase chain reaction was not completed in four cases (2.5 %). Of the 153 evaluable patients, 10 patients (6.5 %) had a mutation in WT1. The incidence of WT1 mutations was significantly higher in CN-AML than in others (15.2 vs. 4.5 %, respectively, P = 0.03). Of the 10 WT1-mutated cases, eight (80 %) had mutations in other genes, including FLT3-ITD in two cases, FLT3-D835 mutation in two, KIT mutation in three, MLL-PTD in three, NRAS mutation in one, and KRAS mutation in two (in some cases, more than one additional gene was mutated). The incidences of KIT and FLT3-D835 mutations were significantly higher in patients with than in those without WT1 mutation. No significant differences were observed in the 3-year overall survival and disease-free survival; however, the presence of WT1 mutation was related to a poor prognosis in patients with CN-AML, excluding those with FLT3-ITD and those younger than 3 years.

NUP98-NSD1 gene fusion and its related gene expression signature are strongly associated with a poor prognosis in pediatric acute myeloid leukemia

The cryptic t(5;11)(q35;p15.5) creates a fusion gene between the NUP98 and NSD1 genes. To ascertain the significance of this gene fusion, we explored its frequency, clinical impact, and gene expression pattern using DNA microarray in pediatric acute myeloid leukemia (AML) patients. NUP98-NSD1 fusion transcripts were detected in 6 (4.8%) of 124 pediatric AML patients. Supervised hierarchical clustering analyses using probe sets that were differentially expressed in these patients detected a characteristic gene expression pattern, including 18 NUP98-NSD1-negative patients (NUP98-NSD1-like patients). In total, a NUP98-NSD1-related gene expression signature (NUP98-NSD1 signature) was found in 19% (24/124) and in 58% (15/26) of cytogenetically normal cases. Their 4-year overall survival (OS) and event-free survival (EFS) were poor (33.3% in NUP98-NSD1-positive and 38.9% in NUP98-NSD1-like patients) compared with 100 NUP98-NSD1 signature-negative patients (4-year OS: 86.0%, 4-year EFS: 72.0%). Interestingly, t(7;11)(p15;p15)/NUP98-HOXA13, t(6;11)(q27;q23)/MLL-MLLT4 and t(6;9)(p22;q34)/DEK-NUP214, which are known as poor prognostic markers, were found in NUP98-NSD1-like patients. Furthermore, another type of NUP98-NSD1 fusion transcript was identified by additional RT-PCR analyses using other primers in a NUP98-NSD1-like patient, revealing the significance of this signature to detect NUP98-NSD1 gene fusions and to identify a new poor prognostic subgroup in AML.

An Inv(16)(p13.3q24.3)-encoded CBFA2T3-GLIS2 fusion protein defines an aggressive subtype of pediatric acute megakaryoblastic leukemia

To define the mutation spectrum in non-Down syndrome acute megakaryoblastic leukemia (non-DS-AMKL), we performed transcriptome sequencing on diagnostic blasts from 14 pediatric patients and validated our findings in a recurrency/validation cohort consisting of 34 pediatric and 28 adult AMKL samples. Our analysis identified a cryptic chromosome 16 inversion (inv(16)(p13.3q24.3)) in 27% of pediatric cases, which encodes a CBFA2T3-GLIS2 fusion protein. Expression of CBFA2T3-GLIS2 in Drosophila and murine hematopoietic cells induced bone morphogenic protein (BMP) signaling and resulted in a marked increase in the self-renewal capacity of hematopoietic progenitors. These data suggest that expression of CBFA2T3-GLIS2 directly contributes to leukemogenesis.

Outcome in 146 patients with paediatric acute myeloid leukaemia treated according to the AML99 protocol in the period 2003-06 from the Japan Association of Childhood Leukaemia Study

The acute myeloid leukaemia (AML) 99 trial conducted previously in Japan for the treatment of de novo paediatric AML showed excellent results, with a 5-year overall survival (OS) and event-free survival (EFS) of 75·6% and 61·6%, respectively. To examine reproducibility of these results in another cohort, the outcome of 146 newly diagnosed AML paediatric patients prospectively registered in the Japan Association of Childhood Leukaemia Study (JACLS) from 2003 to 2006 was compared to that of 240 patients in the original AML 99 clinical trial. The 5-year EFS and OS achieved in the new cohort was 66·7 ± 4·0% and 77·7 ± 8·0% respectively, which were comparable to those obtained in the original AML 99 clinical trial, although less frequent core-binding factor (CBF) AML (29·5% vs. 37%) and an almost equal frequency of allogeneic haematopoietic stem cell transplantation (allo-HSCT) during first complete remission (16·5% vs. 19%) were observed. The 5-year EFS in patients with a normal karyotype (NK) (n = 35, 54·9 ± 15·1%) was inferior in the present cohort when compared to the original AML99 trial. This study confirmed the excellent outcome of the original AML99 protocol.

High WT1 mRNA expression after induction chemotherapy and FLT3-ITD have prognostic impact in pediatric acute myeloid leukemia: a study of the Japanese Childhood AML Cooperative Study Group

The prognostic value of WT1 mRNA expression in pediatric acute myeloid leukemia (AML) remains controversial. A sample of newly diagnosed (n = 158) AML patients from the Japanese Childhood AML Cooperative Treatment Protocol, AML 99, were simultaneously analyzed for WT1 expression, cytogenetic abnormalities and gene alterations (FLT3, KIT, MLL, and RAS). WT1 expression (including more than 2,500 copies/μgRNA) was detected in 122 of the 158 (77.8 %) initial diagnostic AML bone marrow samples (median 45,500 copies/μgRNA). Higher WT1 expression was detected in French American British (FAB)-M0, M3, M7 and lower expression in M4 and M5. Higher WT1 expression was detected in AML with inv(16), t(15;17) and Down syndrome and lower in AML with 11q23 abnormalities. Multivariate analyses demonstrated that FLT3-internal tandem duplication (ITD), KIT mutation, MLL-partial tandem duplication were correlated with poor prognosis; however, higher WT1 expression was not. FLT3-ITD was correlated with WT1 expression and prognosis. Furthermore, 74 WT1 expression after induction chemotherapy was analyzed. Higher WT1 expression after induction chemotherapy was significantly correlated with M1 or M2/M3 marrow, FLT3-ITD and poor prognosis. Multivariate analyses in 74 AML patients revealed that FLT3-ITD, MLL-PTD, and KIT mutations were associated with poor prognosis; however, NRAS Mutation, KRAS mutation and high WT1 expression (>10,000 copies/μgRNA) did not show poor prognosis. Our findings suggest that higher WT1 expression at diagnosis does not correlate with poor prognosis, but that WT1 expression after induction chemotherapy is considered to be a useful predictor of clinical outcome in pediatric AML.

Abstract 1422: High FLT3 mRNA expression without FLT3-ITD in infants with acute myeloid leukemia

Introduction: When compared to older patients, infants with acute leukemia exhibit high frequency of MLL gene rearrangement (MLL-R), and are known to have higher vulnerability to intensive cytotoxic therapy, such as hematopoietic stem cell transplantation (HSCT). In contrast to acute lymphoblastic leukemia (ALL) in infants, there have been a few reports on acute myeloid leukemia (AML) in infants including our group (A. Shimada et al, ASH 2011). We and other group reported that MLL-R had the clinical impact in infant ALL, however, not in infant AML. Infant ALL with MLL-R expressed high FLT3 mRNA, on the other hand, the importance of FLT3 mRNA remains to be obscure in infant AML. Patients: Forty four infants with AML, aged less than 1 year at diagnosis, registered in JPLSG AML-05 from 2006-2010. Patients with Down syndrome were excluded. The most frequent FAB classification type was M7 (18/44, 40.9%), followed by M5 (15/44, 34.1%), and M4 (4/44, 9.0%). Total 16 of 44 (36.4%) infant AML patients had MLL-R, 9 patients were detected by G-banding method, and other 7 patients were by FISH analysis or RT-PCR. There was not t(8;21), t(15;17) except for one inv(16) patient. Methods: FLT3 mRNA expression and internal tandem duplication (ITD) were analyzed in the first diagnostic bone marrow samples by RQ-PCR and PCR. Results: No patients had FLT3-ITD, however, higher FLT3 mRNA expression was found in MLL-R patients (n=16) (median 623,150 copies/μgRNA) compared with MLL-wild type (WT) (n=28) (median 25,105) (p&lt;0.005). This phenomenon was also observed in 12-23 months AML patients. Discussion: High FLT3 mRNA expression was reported in infant ALL with MLL-R and it can be a molecular target for FLT3 inhibitor. On the other hand, there was no report in infant AML. Our previous data suggested that SCT had the limited efficacy for infant AML, FLT3 inhibitor might be considered to be used for infant AML with MLL-R in future.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1422. doi:1538-7445.AM2012-1422

RAS mutations are frequent in FAB type M4 and M5 of acute myeloid leukemia, and related to late relapse: a study of the Japanese Childhood AML Cooperative Study Group

Mutations in RAS are frequent in acute myeloid leukemia (AML), and are thought to contribute to leukemogenesis in a subset of patients; however, their prognostic significance has not been firmly established. One hundred and fifty-seven pediatric patients with AML were analyzed for NRAS and KRAS mutations around hot spots at codons 12, 13, and 61. Twenty-nine patients (18.5%) had an activating mutation of RAS. We found KRAS mutations to be more frequent than NRAS mutations (18/29, 62.1% of patients with RAS mutation), in contrast to previous reports (18-40%). The frequency of RAS mutation was higher in French-American-British types M4 and M5 than other types (P = 0.02). There were no significant differences in other clinical manifestations or distribution in cytogenetic subgroups, or aberrations of other genes, including KIT mutation, FLT3-ITD, and MLL-PTD, between patients with and without RAS mutations. No significant differences were observed in the 3-year overall survival and disease-free survival; however, the presence of RAS mutation was related to late relapse. The occurrence of clinical events at relatively late period should be monitored for in AML patients with mutations in RAS.

Prospective study of a therapeutic regimen with all-trans retinoic acid and anthracyclines in combination of cytarabine in children with acute promyelocytic leukaemia: the Japanese childhood acute myeloid leukaemia cooperative study

In childhood acute promyelocytic leukaemia (APL), the efficacy of therapy combining cytarabine with all-trans retinoic acid (ATRA) and anthracyclines remains unclear in terms of long-term prognosis. Between August 1997 and March 2004, 58 children with APL (median age: 11 years) were enrolled into an acute myeloid leukaemia (AML) study (AML99-M3) and followed up for a median time of 86 months. The regimen included ATRA and anthracyclines combined with cytarabine in both induction and consolidation. In induction, two patients died of haemorrhage and four patients developed retinoic acid syndrome. Of 58 patients, 56 (96·6%) achieved complete remission, two of whom relapsed in the bone marrow after 15 and 19 months respectively. Sepsis was a major complication, with an incidence of 5·6-10·9% in the consolidation blocks, from which all but one of patients recovered. Consequently, 7-year overall and event-free survival rates were 93·1% and 91·4% respectively, and cumulative incidence of relapse plateaued at 3·6% after 2 years. Follow-up survey of 54 patients revealed no patients with late cardiotoxicity or secondary malignancy, except one with asymptomatic prolongation of QTc interval. This study suggests that the combination of cytarabine with ATRA and anthracycline-based therapy may have useful implications in the perspective of long-term prognosis and late adverse effects for childhood APL.

Outcome of childhood acute lymphoblastic leukemia with induction failure treated by the Japan Association of Childhood Leukemia study (JACLS) ALL F-protocol

BACKGROUND

Children with acute lymphoblastic leukemia (ALL) who fail to achieve complete remission (CR) after induction therapy (induction failure: IF) have a poor prognosis; however, there have been few prospective studies in patients with IF.

PATIENTS AND METHODS

Between April 1997 and March 2005, 27 of 1,237 leukemic patients (2.2%) failed to achieve CR after four- or five-drug induction therapy. Twenty-three of these patients entered the F-protocol study, which mainly consisted of acute-myeloid-leukemia-oriented chemotherapy followed by scheduled hematopoietic cell transplantation (HCT).

RESULTS

Seventeen (73.9%) of the 23 patients responded to re-induction chemotherapy with CR. Of note, 15 (93.8%) of 16 patients with Philadelphia-chromosome-negative (non-Ph(+)) ALL achieved CR; in contrast, only 2 (28.6%) of 7 Ph(+) patients achieved CR. Fourteen (82.4%) of 17 patients remained in CR (CCR) until their scheduled HCT, 12 of the 14 with CCR underwent HCT as scheduled, and 6 patients remain in first CR after a median of 78 months (range, 49-107 months). The 5-year overall survival (OS) rates of 16 patients with non-Ph(+) and 7 patients with Ph(+) were 43.8 +/- 12.4% and 14.3 +/- 13.2%, respectively (P = 0.012). The 5-year OS rate of the 17 patients who obtained CR by re-induction therapy and the 6 who did not were 47.1 +/- 12.1% and 0%, respectively (P < 0.001).

CONCLUSION

Acute-myeloid-leukemia-oriented chemotherapy followed by scheduled HCT is a promising treatment strategy for non-Ph(+) ALL patients with IF.

Risk-stratified therapy and the intensive use of cytarabine improves the outcome in childhood acute myeloid leukemia: the AML99 trial from the Japanese Childhood AML Cooperative Study Group

PURPOSE

To improve the prognosis in children with newly diagnosed acute myeloid leukemia (AML) by introducing a dose-dense intensive chemotherapy regimen and an appropriate risk stratification system.

PATIENTS AND METHODS

Two hundred forty children with de novo AML were treated with continuous cytarabine-based induction therapy and stratified to three risk groups based on the initial treatment response, age, and WBC at diagnosis and cytogenetics. All of the patients were treated with intensive consolidation chemotherapy including three or four courses of high-dose cytarabine. Allogeneic hematopoietic stem-cell transplantation (HSCT) was indicated for only the intermediate-risk patients with matched related donors and for all the high-risk subsets.

RESULTS

Two hundred twenty-seven children (94.6%) achieved a complete remission (CR). Four children demonstrated induction death. The median follow-up of the live patients was 55 months (range, 37 to 73 months). The 5-year overall survival of all 240 children was 75.6% (95% CI, 70.3% to 81.4%) and event-free survival was 61.6% (95% CI, 55.8% to 68.1%). The 5-year disease-free survival in each risk group were 71.3% (95% CI, 63.4% to 80.2%) in the low-risk group (n = 112), 59.8% (95% CI, 50.6% to 70.7%) in the intermediate-risk group (n = 92), and 56.5% (95% CI, 39.5% to 80.9%) in the high-risk group (n = 23). Eight children died during the first CR, including four after HSCT.

CONCLUSION

A high survival rate, 75.6% at 5 years, was achieved for childhood with de novo AML in the AML99 trial. The treatment strategy was well tolerated with only 1.7% induction death rate and 3.5% remission death rate. Low-risk children were successfully treated with chemotherapy alone.

The Long Oblique Revision component in revision arthroplasty of the hip

Migration of the acetabular component may give rise to oval-shaped bone defects in the acetabulum. The oblong implant is designed to fill these defects and achieve a stable cementless anchorage with no significant bone loss. We prospectively reviewed 133 oblong long oblique revision components at a mean follow-up of 9.74 years (0.6 to 14). All had been used in revisions for defects of type IIB to IIIB according to Paprosky. Aseptic loosening was the reason for revision in 11 cases (8.3%) and deep infection in seven (5.3%). The probability of implant survival over a 12-year follow-up estimated by the Kaplan-Meier method gave a survival rate of 0.85% respectively 0.90% when deep infection was excluded as the endpoint.

Our study supports the use of these components in defects from IIB to IIIA. The main precondition for success is direct contact of more than half of the surface of the implant with the host acetabular bone.

Tandem duplications of MLL and FLT3 are correlated with poor prognoses in pediatric acute myeloid leukemia: a study of the Japanese childhood AML Cooperative Study Group

BACKGROUND

Mixed-lineage leukemia (MLL)-partial tandem duplication (PTD) is associated with poor prognosis in adult acute myeloid leukemia (AML), but its relationship to pediatric AML is unknown.

PROCEDURE

One hundred fifty-eight newly diagnosed AML patients, including 13 FAB-M3 and 10 Down syndrome (DS) patients, who were treated on the Japanese Childhood AML Cooperative Treatment Protocol AML 99 were analyzed for MLL-PTD, as well as internal tandem duplication (ITD) and the kinase domain mutation (D835Mt) in the FLT3 gene.

RESULTS

We found MLL-PTD in 21 (13.3%) of 158 AML patients, but not in FAB-M3 or DS patients. The differences between patients with and without MLL-PTD were significant for 3-year overall survival (OS) (56.3% vs. 83.2%, P = 0.018), disease-free survival (DFS) (41.7% vs. 69.6%, P = 0.010), and relapse rate (RR) (54.3% vs. 27.6%, P = 0.0085) of 135 AML patients excluding the FAB-M3 and DS patients. Furthermore, ITD and D835Mt in the FLT3 gene were found in 17 (12.6%) and 8 (5.9%) of these 135 patients, respectively. The differences between patients with FLT3-ITD and the wild-type allele were significant for 3-year OS (35.3% and 84.3%, P < 0.0000001), DFS (40.0% and 66.9%, P < 0.003), and RR (52.4% and 30.3%, P < 0.005). Coduplication of both genes was found in only 3 (1.9%) patients.

CONCLUSION

AML patients with FLT3-ITD, but not D835Mt, showed a poor prognosis. AML patients with MLL-PTD were also correlated with poor prognosis in this study.

Prospective study of a pirarubicin, intermediate-dose cytarabine, and etoposide regimen in children with Down syndrome and acute myeloid leukemia: the Japanese Childhood AML Cooperative Study Group

PURPOSE

To evaluate a less intensive chemotherapeutic regimen specifically designed for patients with Down syndrome (DS) and acute myeloid leukemia (AML), and to determine the prognostic factors for event-free survival.

PATIENTS AND METHODS

Seventy-two patients with AML-DS were treated with remission induction chemotherapy consisting of pirarubicin (25 mg/m2/d for 2 days), cytarabine (100 mg/m2/d for 7 days), and etoposide (150 mg/m2/d for 3 days). Patients received four courses of intensification therapy of the same regimen. Prophylaxis for CNS leukemia was not included.

RESULTS

All but two patients were younger than 4 years, and 67 of the 72 patients (93%) were diagnosed as acute megakaryoblastic leukemia (AMKL). Seventy of the 72 patients (97.2%) achieved a complete remission (CR), and the estimated 4-year event-free survival (EFS) rate was 83% +/- 9%. Nine patients relapsed, and one died as a result of pneumonia during CR. Multivariate analysis revealed that the presence of monosomy 7 was a greater risk factor of adverse outcome (odds ratio = 5.67; P = .027).

CONCLUSION

A less intensive chemotherapeutic regimen produces excellent outcomes in standard-risk AML-DS patient. Risk-oriented therapy should be considered for future trials in AML-DS.