Prognostic significance of chromosomal abnormalities at relapse in children with relapsed acute myeloid leukemia: A retrospective cohort study of the Relapsed AML 2001/01 Study

BACKGROUND

In addition to treatment response, cytogenetic and molecular aberrations are the most important prognostic factors in children with de novo acute myeloid leukemia (AML). However, little is known about cytogenetics at the time of relapse.

METHODS

This international study analyzed the prognostic value of cytogenetic profiles and karyotypic changes in pediatric relapsed AML in relation to the probability of event-free (pEFS) and overall survival (pOS). For this purpose, cytogenetic reports from all patients registered on the Relapsed AML 2001/01 Study were reviewed and classified.

RESULTS

Cytogenetic information at relapse was available for 403 (71%) of 569 registered patients. Frequently detected aberrations at relapse were t(8;21)(q22;q22) (n = 60) and inv(16)(p13.1q22)/t(16;16)(p13.1;q22) (n = 24), both associated with relatively good outcome (4-year pOS 59% and 71%, respectively). Monosomy 7/7q-, t(9;11)(p22;q23), t(10;11)(p12;q23), and complex karyotypes were associated with poor outcomes (4-year pOS 17%, 19%, 22%, and 22%, respectively). Of 261 (65%) patients for whom cytogenetic data were reliable at both diagnosis and relapse, pEFS was inferior for patients with karyotypic instability (n = 128, 49%), but pOS was similar. Unstable karyotypes with both gain and loss of aberrations were associated with inferior outcome. Early treatment response, time to relapse, and cytogenetic profile at time of relapse were the most important prognostic factors, both outweighing karytoypic instability per se.

CONCLUSION

The cytogenetic subgroup at relapse is an independent risk factor for (event-free) survival. Cytogenetic assessment at the time of relapse is of high importance and may contribute to improved risk-adapted treatment for children with relapsed AML.

Recommendations for Diagnosis and Treatment of Children with Transient Abnormal Myelopoiesis (TAM) and Myeloid Leukemia in Down Syndrome (ML-DS)

Children with Down syndrome are at a high risk of developing transient abnormal myelopoiesis (TAM; synonym: TMD) or myeloid leukemia (ML-DS). While most patients with TAM are asymptomatic and go into spontaneous remission without a need for therapy, around 20% of patients die within the first six months due to TAM-related complications. Another 20-30% of patients progress from TAM to ML-DS. ML-DS patients are particularly vulnerable to therapy-associated toxicity, but the prognosis of relapsed ML-DS is extremely poor - thus, ML-DS therapy schemata must strive for a balance between appropriate efficacy (to avoid relapses) and treatment-related toxicity. This guideline presents diagnostic and therapeutic strategies for TAM and ML-DS based on the experience and results of previous clinical studies from the BFM working group, which have helped reduce the risk of early death in symptomatic TAM patients using low-dose cytarabine, and which have achieved excellent cure rates for ML-DS using intensity-reduced treatment protocols.

Health status, health-related quality of life, and socioeconomic outcome in childhood brain tumor survivors: a German cohort study

BACKGROUND

With rising numbers of childhood cancer survivors, somatic and socioeconomic outcome as well as health-related quality of life (QoL) gain increasing relevance. Based on the first nationwide German Survey on Life Situation, State of Health, and Quality of Life of Childhood Cancer Survivors, the VIVE survey, we report the outcome of survivors of childhood brain tumors localized in the posterior fossa.

METHODS

Two hundred seventy participants with a median follow-up period of 21.9 years completed a questionnaire on socioeconomic and somatic late effects as well as a standardized QoL questionnaire (European Organisation for Research and Treatment of Cancer QLQ-C30). Comparisons were performed between World Health Organization (WHO) grades I-II, WHO grades III-IV brain tumor survivors (BTS), and the general population adjusting for potential confounders.

RESULTS

The socioeconomic and QoL results of WHO grades I-II BTS were largely comparable to the general population, while grades III-IV BTS were at higher risk for significantly worse outcomes. Of WHO grades III-IV BTS, 36.8% were still living with their parents or in assisted living facilities compared with 16.1% of grades I-II BTS and 7.8% of the age-adjusted general population. Of grades III-IV BTS, 60.8% achieved at least an intermediate school degree in comparison to 80.5% of grades I-II BTS and 75.6% of the general population. Grades III-IV BTS developed up to 2 times more somatic late effects than survivors of grades I-II tumors.

CONCLUSION

Derived from a large and homogeneous cohort, these results stress the importance of an appropriate follow-up period focusing not only on physical aspects but encompassing the entire living situation to allow patient-tailored support.

[Long-Term Follow-Up in Childhood Cancer Survivors - Position paper 2018 of the working group "long-term follow-up" of the Society of Pediatric Oncology and Hematology (GPOH) on long-term surveillance, long-term follow-up and late effect evaluation in pediatric oncology patients]

Nowadays, childhood cancer patients survive much more often than they did 40 years ago. Therefore, the cure rates rise over 80%. Approximately 33,000 cured childhood cancer patients are documented by the German Childhood Cancer Registry (GCCR) for long-term follow-up in Germany. But does that mean, they are healthy, too? When compared to the normal population, it can be seen that morbidity and mortality are significantly higher among former childhood cancer patients. In two out of three survivors, the cancer and its treatments can lead to treatment-related late complications 30 years later; in about one-third, these late complications are classified as severe. A structured long-term follow-up is needed to detect and to treat new diseases early. The purpose of this position paper is to update the first position paper from 2007. Current developments are described, how appropriate aftercare structures and aftercare facilities should be planned, taking into account existing structures and increasing needs.

Akute Promyelozyten-Leukämie: Neue Behandlungsstrategien mit ATRA und ATO – AML-BFM-Empfehlungen

Die Behandlung der Akuten Promyelozyten-Leukämie (APL) hat sich in den letzten Jahren deutlich geändert. Heute können APL Patienten mit Standardrisiko – (auch als Niedrigrisiko bezeichnet) ohne Chemotherapie nur mit all-trans-Retinsäure (ATRA) und Arsentrioxid (ATO) behandelt werden. Bei Hochrisikopatienten sollte eine Induktions-Chemotherapie hinzugefügt werden. Die kurativen Ergebnisse sind gut und vergleichbar mit jenen, die in der Vergangenheit mit Chemotherapie plus ATRA erzielt wurden. Toxizitäten, insbesondere infektiöse Komplikationen sind jedoch deutlich seltener. Das Hauptrisiko bleiben frühe letale Blutungen. Durch rechtzeitige Diagnose und frühe ATRA-Behandlung kann dieses Risiko reduziert werden. In der vorliegenden Übersicht werden die aktuellen Behandlungsstrategien und Empfehlungen für APL bei Kindern dargestellt und diskutiert.

Acute myelogenous leukemia in adolescents and young adults

The incidence of acute myelogenous leukemia (AML) increases progressively with age. Favorable genetic mutations are most prevalent in children, and unfavorable profiles increase proportionately in adolescents and young adults (AYA) and into later adulthood. Survival rates of AYA have improved over recent decades to 50-60%, but their accrual to clinical trials remains poor. In contrast to AYA with acute lymphoblastic leukemia, the prognostic benefit for AYA with AML enrolled in pediatric compared with adult trials is minor and only seen when different protocols are used. The distinctive needs of AYA, including intensive psychological services, call for their treatment within specialized centers that offer complex supportive care.

Gemtuzumab ozogamicin in children with relapsed or refractory acute myeloid leukemia: a report by Berlin-Frankfurt-Münster study group

Despite intensified salvage treatments, children with relapsed/refractory acute myeloid leukemia (AML) have poor survival. We evaluated gemtuzumab ozogamicin (CD33-targeted drug) used on a compassionate basis in patients diagnosed from 1995 until 2014 within Acute Myeloid Leukemia Berlin-Frankfurt-Münster studies, and identified 76 patients (<18 years) with highly-advanced and pre-treated AML [refractory de novo acute myeloid leukemia (n=10), de novo AML refractory to relapse (1^st early: n=41; 1^st late: n=10; 2^nd or more: n=10), and secondary AML (n=5)]. At doses of 2.5–10 mg/m², gemtuzumab ozogamicin was administered in 1-4 cycles as single agent (47%), combined with cytarabine (47%), or others (6%). Most common grade 3/4 adverse events were infections or febrile neutropenia (78% of severe adverse events), infusion-related immunological reactions (6%), and gastrointestinal symptoms (5%). Three patients experienced veno-occlusive disease (one fatal due to exacerbation of a pre-existing cardiomyopathy). Sixty-four percent received subsequent hematopoietic stem cell transplantation. Probability of 4-year overall survival was 18±5% in all, 27±7% in patients with and 0% in patients without hematopoietic stem cell transplantation (P<0.0001). Administration of gemtuzumab ozogamicin on a patient-specific, compassionate use basis was frequently considered in our study group and proved to be effective for bridging children with very advanced AML to hematopoietic stem cell transplantation. Uniform prospective studies for these patients are urgently needed.

Characteristics and outcome in patients with central nervous system involvement treated in European pediatric acute myeloid leukemia study groups

BACKGROUND

There is no consensus on the treatment for pediatric patients with acute myeloid leukemia and initial central nervous system (CNS) involvement.

METHODS

To evaluate different CNS-directed treatment options (intrathecal [IT] therapy, CNS irradiation, hematopoietic stem cell transplantation [HSCT]), 261 patients (excluding acute promyelocytic leukemia) with initial CNS involvement treated in trials with similar intensive chemotherapy by four cooperative European study groups (1998-2013) were studied and compared with CNS-negative patients from the Berlin-Frankfurt-Münster group.

RESULTS

Patient characteristics in the different study groups were comparable. Young age, high white blood cell count, extramedullary involvement other than the CNS, monoblastic morphology, and inv(16) were associated with CNS involvement (each P < 0.0001). There were no major differences in outcome between the study groups. The cumulative incidence of relapse (CIR) regarding the CNS was higher in initially CNS-positive versus initially CNS-negative patients (all: 8 ± 2% vs. 3 ± 1%, P_(Gray) = 0.001; isolated: 4 ± 1% vs. 1 ± 0%, P_(Gray) = 0.03). However, global outcome of the CNS-positive cohort (overall survival, 64 ± 3%; event-free survival 48 ± 3%; and CIR 33% ± 3%) did not differ significantly from CNS-negative patients. Risk groups defined by cytogenetics were of likewise prognostic significance in CNS-positive and -negative patients. CNS treatment with cranial irradiation was not superior compared to IT therapy and systemic chemotherapy (± HSCT).

CONCLUSION

Although CNS relapses occurred more frequently in initially CNS-positive patients, their global outcome was similar as in CNS-negative patients. Intensified IT therapy was heterogeneous; however, at least eight applications, preferably with triple IT chemotherapy, seem to be appropriate to accompany dose-intensive systemic chemotherapy.

First experience of the AML-Berlin-Frankfurt-Münster group in pediatric patients with standard-risk acute promyelocytic leukemia treated with arsenic trioxide and all-trans retinoid acid

Recently, studies in adults with acute promyelocytic leukemia (APL) showed high cure rates in low-risk patients treated with all-trans retinoid acid (ATRA) and arsenic trioxide (ATO), while toxicities were significantly reduced compared to the standard treatment with ATRA and chemotherapy. Here we report about first experience with 11 pediatric patients with low-risk APL treated with ATRA and ATO. All patients stayed in molecular remission. All suffered from hyperleukocytosis. Two patients experienced reversible severe side effects. One suffered from osteonecroses at both femurs, seizures, as well as posterior reversible encephalopathy syndrome, the other patient had an abducens paresis.

Hematologic Response to Vorinostat Treatment in Relapsed Myeloid Leukemia of Down Syndrome

Children with Down syndrome are at high risk to develop myeloid leukemia (ML-DS). Despite their excellent prognosis, children with ML-DS particularly suffer from severe therapy-related toxicities and for relapsed ML-DS the cure rates are very poor. Here we report the clinical course of one child with ML-DS treated with the histone deacetylase (HDAC) inhibitor vorinostat (suberoylanilide hydroxamic acid) after second relapse. The child had previously received conventional chemotherapy and stem cell transplantation, yet showed a remarkable clinical and hematologic response. Thus, HDAC inhibitor may represent an effective class of drugs for the treatment of ML-DS.

Lack of Effectiveness of Neutropenic Diet and Social Restrictions as Anti-Infective Measures in Children With Acute Myeloid Leukemia: An Analysis of the AML-BFM 2004 Trial

PURPOSE

Although nonpharmacologic anti-infective measures are widely used in children treated for acute myeloid leukemia (AML), there is little evidence of their effectiveness.

PATIENTS AND METHODS

We analyzed infectious complications in children during intensive treatment of AML according to the AML-BFM 2004 trial and surveyed sites on institutional standards regarding recommended restrictions of social contacts (six items), pets (five items), and food (eight items). A scoring system was developed with a restriction score for each item. Multivariable Poisson regression adjusted for sex, age, weight group, risk stratification, and prophylactic antibiotics was used to estimate the impact of the restrictions on the incidence ratios of fever of unknown origin, bacteremia, pneumonia, and gastroenteritis.

RESULTS

Data on recommendations of nonpharmacologic anti-infective measures and infectious complications were available in 339 patients treated in 37 institutions. Analyses did not demonstrate a significant benefit of any of the restrictions regarding food, social contacts, and pets on the risk of fever, bacteremia, pneumonia, and gastroenteritis. In contrast, age, weight group, risk stratification, and nonabsorbable antibiotics had some influence on infections complications.

CONCLUSION

The lack of effectiveness of dietary restrictions and restrictions regarding social contacts and pets should result in reconsideration of anti-infective policies.

Glucocorticoid-Induced Proliferation in Untreated Pediatric Acute Myeloid Leukemic Blasts

We evaluated the in vitro glucocorticoid (GC) responsiveness of 117 pediatric acute myeloid leukemia cells by considering GC resistance, GC-induced proliferation, and GC-induced differentiation. None of the samples was highly GC sensitive, and only 15% were intermediately sensitive. GC-induced differentiation was not observed, while GC-induced proliferation was observed in 27% of the samples. Samples with French-American-British classification (FAB) type M5 or activating Fms-like tyrosine kinase 3 (FLT3) mutations were significantly more prone to this phenomenon. Although we could not confirm this in our study, if induced proliferation in vitro is paralleled in vivo, GCs during consolidation may have adverse effects on minimal residual leukemic cells, which might increase relapse risk.

Infectious Complications in Children With Acute Myeloid Leukemia and Down Syndrome: Analysis of the Prospective Multicenter Trial AML-BFM 2004

BACKGROUND

Children with acute myeloid leukemia (AML) and Down syndrome have high survival rates with intensity-reduced chemotherapeutic regimens, although the optimal balance between dose intensity and treatment toxicity has not been determined. We, therefore, characterized infectious complications in children with AML and Down syndrome treated according to AML-BFM 2004 study (ClinicalTrials.gov NCT00111345; amended 2006 for Down syndrome with reduced intensity).

PROCEDURE

Data on infectious complications were gathered from the medical records in the hospital where the patient was treated. Infectious complications were categorized as fever without identifiable source (FUO), or as microbiologically or clinically documented infections.

RESULTS

A total of 157 infections occurred in 61 patients (60.5% FUO, 9.6% and 29.9% clinically and microbiologically documented infections, respectively). Almost 90% of the pathogens isolated from the bloodstream were Gram-positive bacteria, and approximately half of them were viridans group streptococci. All seven microbiologically documented episodes of pneumonia were caused by viruses. Infection-related mortality was 4.9%, and all three patients died due to viral infection.

CONCLUSIONS

Our data demonstrate that a reduced-intensity chemotherapeutic regimen in children with AML and Down syndrome is still associated with high morbidity. Although no patient died due to bacteria or fungi, viruses were responsible for all lethal events. Future studies, therefore, have to focus on the impact of viruses on morbidity and mortality of patients with AML and Down syndrome.

Exchange Transfusion and Leukapheresis in Pediatric Patients with AML With High Risk of Early Death by Bleeding and Leukostasis

BACKGROUND

The risk of early death (ED) by bleeding/leukostasis is high in patients with AML with hyperleukocytosis (>100,000/μl). Within the pediatric AML-BFM (Berlin-Frankfurt-Münster) 98/04 studies, emergency strategies for these children included exchange transfusion (ET) or leukapheresis (LPh). Risk factors for ED and interventions performed were analyzed.

PATIENTS

Two hundred thirty-eight of 1,251 (19%) patients with AML presented with hyperleukocytosis; 23 of 1,251 (1.8%) patients died of bleeding/leukostasis.

RESULTS

ED due to bleeding/leukostasis was highest at white blood cell (WBC) count >200,000/μl (14.3%). ED rates were even higher (20%) in patients with FAB (French-American-British) M4/M5 and hyperleukocytosis >200,000/μl. Patients with WBC >200,000/μl did slightly better with ET/LPh compared to those without ET/LPh (ED rate 7.5% vs. 21.2%, P = 0.055). Multivariate WBC >200,000/μl was of strongest prognostic significance for ED (P(χ(2) ) <0.0001).

CONCLUSION

Our data confirm the high risk of bleeding/leukostasis in patients with hyperleukocytosis. ET/LPh shows a trend toward reduced ED rate due to bleeding/leukostasis and is recommended at WBC >200,000/μl, and in FAB M4/M5 even at lower WBC.

Coexpression of Multiple ABC-Transporters is Strongly Associated with Treatment Response in Childhood Acute Myeloid Leukemia

BACKGROUND

To analyze whether expression of ABC-transporters is associated with remission rate and long-term outcome in a prospective clinical trial of childhood acute myeloid leukemia (AML).

PROCEDURE

The expression of four ABC-transporter genes (ABCA3 encoding drug transporter ABCA3, ABCB1 encoding multidrug resistance protein 1, ABCC3 encoding multidrug resistance-associated protein 3, and ABCG2 encoding breast cancer resistance protein) was measured by TaqMan real time polymerase chain reaction in pretreatment samples from 112 children with AML. Patients were treated according to multicenter study AML-Berlin, Frankfurt, Munich (BFM) 2004.

RESULTS

ABCC3 (P = 0.009) and ABCG2 (P = 0.03) were associated with a lower chance to achieve remission after the first course of chemotherapy. ABCC3 was associated with lower relapse free survival (RFS) (P = 0.02). ABCG2 was expressed at higher levels in subtypes of AML with favorable outcome but within standard- and high-risk patients, it was associated with poor outcome (P = 0.02). A strong association was observed between the number of overexpressed ABC-transporters and the chance to achieve remission (P = 0.01) or the chance of RFS (P < 0.001).

CONCLUSIONS

The intensive treatment regimen of AML-BFM 2004 did not readily overcome drug resistance caused by ABC-transporters. Inhibition of ABC-transporters might be particularly useful in patients who express multiple of these genes.

Infectious complications in children with acute myeloid leukemia: decreased mortality in multicenter trial AML-BFM 2004

Infections are an important cause for morbidity and mortality in pediatric acute myeloid leukemia (AML). We therefore characterized infectious complications in children treated according to the trial AML-BFM 2004. Patients with Down syndrome were excluded from the analysis. Data were gathered from the medical records in the hospital where the patients were treated. A total of 405 patients (203 girls; median age 8.4 years) experienced 1326 infections. Fever without identifiable source occurred in 56.1% of the patients and clinically and microbiologically documented infections in 17.5% and 32.4% of the patients, respectively. In all, 240 Gram-positive (112 viridans group streptococci) and 90 Gram-negative isolates were recovered from the bloodstream. Invasive fungal infection was diagnosed in 3% of the patients. Three children each died of Gram-negative bacteremia and invasive aspergillosis, respectively. As compared with the results of AML-BFM 93 with lower dose intensity, infection-related morbidity was slightly higher in AML-BFM 2004 (3.3. versus 2.8 infections per patient), whereas infection-related mortality significantly decreased (1.5% versus 5.4% P=0.003). Specific anti-infective recommendations included in the treatment protocol, regular training courses for pediatric hematologists and increasing experience may be the reason for reduced infection-related mortality in children with AML. Further studies are needed to decrease infection-related morbidity.

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.

Collaborative Efforts Driving Progress in Pediatric Acute Myeloid Leukemia

Diagnosis, treatment, response monitoring, and outcome of pediatric acute myeloid leukemia (AML) have made enormous progress during the past decades. Because AML is a rare type of childhood cancer, with an incidence of approximately seven occurrences per 1 million children annually, national and international collaborative efforts have evolved. This overview describes these efforts and includes a summary of the history and contributions of each of the main collaborative pediatric AML groups worldwide. The focus is on translational and clinical research, which includes past, current, and future clinical trials. Separate sections concern acute promyelocytic leukemia, myeloid leukemia of Down syndrome, and relapsed AML. A plethora of novel antileukemic agents that have emerged, including new classes of drugs, are summarized as well. Finally, an important aspect of the treatment of pediatric AML--supportive care--and late effects are discussed. The future is bright, with a wide range of emerging innovative therapies and with more and more international collaboration that ultimately aim to cure all children with AML, with fewer adverse effects and without late effects.

Randomised Introduction of 2-CDA as Intensification during Consolidation for Children with High-risk AML--results from Study AML-BFM 2004

BACKGROUND

The outcome in children and adolescents with high-risk (HR) acute myeloid leukemia (AML) is still unsatisfactory. Therefore, in study AML-BFM 2004 we aimed to improve outcome of HR-patients by adding moderately dosed 2-Chloro-2-Deoxyadenosine (2-CDA) to the respective consolidation treatment backbone without increasing toxicity. The aim was to improve prognosis especially in FAB M4/M5/MLL patients, who represent the largest subgroup of HR patients.

PATIENTS AND METHODS

In total, 343 children and adolescents with HR-AML were randomized to receive or not 2-CDA (6 mg/m²/d, days 1, 3) in combination with cytarabine/idarubicine (AI=500 mg/m² cytarabine 5 days continuous infusion plus 7 mg/m²/d idarubicin, days 3 and 5).

RESULTS

RESULTS for patients of the AI/2-CDA arm (n=168) vs. the AI-arm (n=175) were similar: 5-year overall survival 68±4 vs. 72±4%, plogrank=0.38, event-free survival 53±4 vs. 49±4%, plogrank=0.77; cumulative incidence of relapse at 5 years: 35±4 vs. 37±4%, p(Gray)=0.89. RESULTS in patients with MLL rearrangement or FAB M4/M5 were also similar in the treatment groups. In addition, toxicities did not differ between the two arms.

CONCLUSION

We conclude that additional, moderate dose 2-CDA does not improve prognosis in HR-patients when given during consolidation treatment. Its effect might be too low in this multidrug regimen, where the strongest effects are achieved during induction, or the chosen dose of 2-CDA might have been too low.

Improved outcome of pediatric patients with acute megakaryoblastic leukemia in the AML-BFM 04 trial

Despite recent advances in the treatment of children with acute megakaryoblastic leukemia (AMKL) using intensified treatment protocols, clear prognostic indicators, and treatment recommendations for this acute myeloid leukemia (AML) subgroup are yet to be defined. Here, we report the outcome of 97 pediatric patients with de novo AMKL (excluding Down syndrome [DS]) enrolled in the prospective multicenter studies AML-BFM 98 and AML-BFM 04 (1998-2014). AMKL occurred in 7.4 % of pediatric AML cases, at younger age (median 1.44 years) and with lower white blood cell count (mean 16.5 × 10⁹/L) as compared to other AML subgroups. With 60 ± 5 %, children with AMKL had a lower 5-year overall survival (5-year OS; vs. 68 ± 1 %, P_{log rank} = 0.038). Yet, we achieved an improved 5-year OS in AML-BFM 04 compared to AML-BFM 98 (70 ± 6 % vs. 45 ± 8 %, P_{log rank} = 0.041). Allogeneic hematopoietic stem cell transplantation in first remission did not provide a significant survival benefit (5-year OS 70 ± 11 % vs. 63 ± 6 %; P_Mantel-Byar = 0.85). Cytogenetic data were available for n = 78 patients. AMKL patients with gain of chromosome 21 had a superior 5-year OS (80 ± 9 %, P_{log rank} = 0.034), whereas translocation t(1;22)(p13;q13) was associated with an inferior 5-year event-free survival (38 ± 17 %, P_{log rank} = 0.04). However, multivariate analysis showed that treatment response (bone marrow morphology on day 15 and 28) was the only independent prognostic marker (RR = 4.39; 95 % CI, 1.97–9.78). Interestingly, GATA1-mutations were detected in six patients (11 %) without previously known trisomy 21. Thus, AMKL (excluding DS) remains an AML subgroup with inferior outcome. Nevertheless, with intensive therapy regimens, a steep increase in the survival rates was achieved.

Gene expression profiles associated with pediatric relapsed AML

Development of relapse remains a problem for further improvements in the survival of pediatric AML patients. While virtually all patients show a good response to initial treatment, more patients respond poorly when treated at relapse. The cellular characteristics of leukemic blast cells that allow survival of initial treatment, relapse development and subsequent resistance to salvage treatment remain largely elusive. Therefore, we studied if leukemic blasts at relapse biologically resemble their initial diagnosis counterparts. We performed microarray gene expression profiling on paired initial and relapse samples of 23 pediatric AML patients. In 11 out of 23 patients, gene expression profiles of initial and corresponding relapse samples end up in different clusters in unsupervised analysis, indicating altered gene expression profiles. In addition, shifts in type I/II mutational status were found in 5 of these 11 patients, while shifts were found in 3 of the remaining 12 patients. Although differentially expressed genes varied between patients, they were commonly related to hematopoietic differentiation, encompassed genes involved in chromatin remodeling and showed associations with similar transcription factors. The top five were CEBPA, GFI1, SATB1, KLF2 and TBP. In conclusion, the leukemic blasts at relapse are biologically different from their diagnosis counterparts. These differences may be exploited for further development of novel treatment strategies.

Prospective validation of a new method of monitoring minimal residual disease in childhood acute myelogenous leukemia

PURPOSE

This study evaluated the prognostic impact of a novel, simple, and standardized assay for monitoring minimal residual disease (MRD) in pediatric acute myelogenous leukemia (AML).

EXPERIMENTAL DESIGN

The expression of seven leukemia-associated genes (WT1, PRAME, CCL23, GAGED2, MSLN, SPAG6, and ST18) was measured by TaqMan Low Density Arrays in 112 patients and 52 healthy controls. Patients were treated according to the multicenter study AML-BFM 2004. Samples were collected prospectively at standard time points. The laboratory that measured MRD was blinded to patient outcome.

RESULTS

Relapse-free survival (RFS) was 95% (N = 19; SE = 5%) if expression of all genes was down to normal on day 15, 63% (N = 41; SE = 8%) if expression was normalized on day 28, and 38% (N = 21; SE = 11%) in patients who still showed elevated expression on day 28. The prognostic impact of MRD remained significant (P = 0.002) when patients were stratified for the AML-BFM 2004 risk group. Multivariate analysis identified the MRD risk group and day 28 cytology as the only independent prognostic factors. Patients with a cytologic nonremission on day 28, which was confirmed by MRD, had a dismal prognosis. Only 1 out of 8 patients survived without relapse.

CONCLUSIONS

This novel method of monitoring MRD has a strong prognostic impact that is independent from established risk factors in childhood AML.

Re-induction with L-DNR/FLAG improves response after AML relapse, but not long-term survival

BACKGROUND

According to the results of the international study Relapsed AML 2001/01 response was better after re-induction with L-DNR/FLAG (liposomal daunorubicin, fludarabine, cytarabine, G-CSF) compared to FLAG only but survival rate was not improved. However, the findings might be group-specific.

METHOD

Patient characteristics, actual therapy given and long-term course of the disease in 155 pediatric patients (including non-randomized) with first relapse and 10 primary nonresponders treated in Germany were analyzed.

RESULTS

Overall 4-year survival rates after relapse were similar in the 2 treatment groups L-DNR/FLAG and FLAG (0.43 ± 0.05 vs. 0.47 ± 0.06, p(log-rank)=0.47). The rate of randomization was low (65%) and 5% of the 101 randomized patients changed the treatment arm. Therefore, induction was based in 40% patients on an individual decision with preference for L-DNR/FLAG. There were less patients with favorable cytogenetics and morphology in the L-DNR/FLAG-group (p<0.04). Response to the first re-induction course at day 28 tended to be more unfavorable with FLAG only. In this patient group protocol intensifications were more frequent as compared to the L-DNR/FLAG-group (p=0.07), and late CR could be achieved after intensification in 9/18 poor responding patients.

CONCLUSION

The initial selection bias of relapse patients with unfavorable risk factors to the disadvantage of the L-DNR/FLAG-group and the more drug- and time-intensive treatment after 1(st) re-induction given in the FLAG-group may have nullified the initial beneficial effect of L-DNR containing re-induction therapy and led to similar and relatively favorable survival rates in both treatment groups in Germany.

Clinical relevance of molecular aberrations in paediatric acute myeloid leukaemia at first relapse

Outcome for relapsed paediatric acute myeloid leukaemia (AML) remains poor. Strong prognostic factors at first relapse are lacking, which hampers optimization of therapy. We assessed the frequency of molecular aberrations (FLT3, NRAS, KRAS, KIT, WT1 and NPM1 genes) at first relapse in a large set (n = 198) of relapsed non-French-American-British M3, non-Down syndrome AML patients that received similar relapse treatment. We correlated molecular aberrations with clinical and biological factors and studied their prognostic relevance. Hotspot mutations in the analysed genes were detected in 92 out of 198 patients (46·5%). In 72 of these 92 patients (78%), molecular aberrations were mutually exclusive for the currently analysed genes. FLT3-internal tandem repeat (ITD) (18% of total group) mutations were most frequent, followed by NRAS (10·2%), KRAS (8%), WT1 (8%), KIT (8%), NPM1 (5%) and FLT3-tyrosine kinase domain (3%) mutations. Presence of a WT1 aberration was an independent risk factor for second relapse (Hazard Ratio [HR] = 2·74, P = 0·013). In patients who achieved second complete remission (70·2%), WT1 and FLT3-ITD aberrations were independent risk factors for poor overall survival (HR = 2·32, P = 0·038 and HR = 1·89, P = 0·045 respectively). These data show that molecular aberrations at first relapse are of prognostic relevance and potentially useful for risk group stratification of paediatric relapsed AML and for identification of patients eligible for personalized treatment.

The prognostic significance of early treatment response in pediatric relapsed acute myeloid leukemia: results of the international study Relapsed AML 2001/01

The prognostic significance of early response to treatment has not been reported in relapsed pediatric acute myeloid leukemia. In order to identify an early and easily applicable prognostic factor allowing subsequent treatment modifications, we assessed leukemic blast counts in the bone marrow by morphology on days 15 and 28 after first reinduction in 338 patients of the international Relapsed-AML2001/01 trial. Both day 15 and day 28 status was classified as good (≤20% leukemic blasts) in 77% of patients. The correlation between day 15 and 28 blast percentages was significant, but not strong (Spearman correlation coefficient = 0.49, P<0.001). Survival probability decreased in a stepwise fashion along with rising blast counts at day 28. Patients with bone marrow blast counts at this time-point of ≤5%, 6-10%, 11-20% and >20% had 4-year probabilities of survival of 52%±3% versus 36%±10% versus 21%±9% versus 14%±4%, respectively, P<0.0001; this trend was not seen for day 15 results. Multivariate analysis showed that early treatment response at day 28 had the strongest prognostic significance, superseding even time to relapse (< or ≥12 months). In conclusion, an early response to treatment, measured on day 28, is a strong and independent prognostic factor potentially useful for treatment stratification in pediatric relapsed acute myeloid leukemia. This study was registered with ISRCTN code: 94206677.

Effective childhood cancer treatment: the impact of large scale clinical trials in Germany and Austria

In Germany and Austria, more than 90% of pediatric cancer patients are enrolled into nationwide disease-specific first-line clinical trials or interim registries. Essential components are a pediatric cancer registry and centralized reference laboratories, imaging review, and tumor board assistance. The five-year overall survival rate in countries where such infrastructures are established has improved from <20% before 1950 to >80% since 1995. Today, treatment intensity is tailored to the individual patient's risk to provide the highest chances of survival while minimizing deleterious late effects. Multicenter clinical trials are internationalized and serve as platforms for further improvements by novel drugs and biologicals.

Development of a curative treatment within the AML-BFM studies

The first multicenter treatment study for AML in childhood in Germany was performed from 1978 onwards. The therapy plan was designed similar to that for the acute lymphoblastic leukaemia (ALL). The drugs with the highest efficacy in AML, cytarabine cutting catara-bine and anthracyclines, were combined during induction and consolidation, followed by preventive cranial irradiation and maintenance therapy similar to that in ALL. The remission rate of the initial study was 80%, and the 5-year survival rate increased from less than 10% before 1970 to 40%. 5 subsequent trials have further increased the 5-year survival to now 70% and even 90% in the subgroup of core-binding factor leukaemias by using an intensified and optimised treatment schedule.The AML-BFM studies were the only prospective study sequence testing the benefit of cranial irradiation. Results from study -87 including the non-randomized patients showed an increased risk of CNS and/or bone marrow relapses in non-irradiated patients. Later on there was evidence that 12 Gy resulted in the same relapse rate as 18 Gy. The AML-BFM studies always used the experience from the previous study to optimize the next study. This approach was essential together with improved supportive treatment and experience of the medical staff for the step-wise and considerable increase of longterm survival within the 6 subsequent AML-BFM studies.

Improved outcome in pediatric relapsed acute myeloid leukemia: results of a randomized trial on liposomal daunorubicin by the International BFM Study Group

PURPOSE

In pediatric relapsed acute myeloid leukemia (AML), optimal reinduction therapy is unknown. Studies suggest that liposomal daunorubicin (DNX; DaunoXome; Galen, Craigavon, United Kingdom) is effective and less cardiotoxic, which is important in this setting. These considerations led to a randomized phase III study by the International Berlin-Frankfurt-Münster Study Group.

PATIENTS AND METHODS

Patients with relapsed or primary refractory non-French-American-British type M3 AML who were younger than 21 years of age were eligible. Patients were randomly assigned to fludarabine, cytarabine, and granulocyte colony-stimulating factor (FLAG) or to FLAG plus DNX in the first reinduction course. The primary end point was status of the bone marrow (BM) sampled shortly before the second course of chemotherapy (the day 28 BM). Data are presented according to intention-to-treat for all 394 randomly assigned patients (median follow-up, 4.0 years).

RESULTS

The complete remission (CR) rate was 64%, and the 4-year probability of survival (pOS) was 38% (SE, 3%). The day 28 BM status (available in 359 patients) was good (≤ 20% leukemic blasts) in 80% of patients randomly assigned to FLAG/DNX and 70% for patients randomly assigned to FLAG (P = .04). Concerning secondary end points, the CR rate was 69% with FLAG/DNX and 59% with FLAG (P = .07), but overall survival was similar. However, core-binding factor (CBF) AML treated with FLAG/DNX resulted in pOS of 82% versus 58% with FLAG (P = .04). Grade 3 to 4 toxicity was essentially similar in both groups.

CONCLUSION

DNX added to FLAG improves early treatment response in pediatric relapsed AML. Overall long-term survival was similar, but CBF-AML showed an improved survival with FLAG/DNX. International collaboration proved feasible and resulted in the best outcome for pediatric relapsed AML reported thus far.

Engagement of SIRPα inhibits growth and induces programmed cell death in acute myeloid leukemia cells

BACKGROUND

Recent studies show the importance of interactions between CD47 expressed on acute myeloid leukemia (AML) cells and the inhibitory immunoreceptor, signal regulatory protein-alpha (SIRPα) on macrophages. Although AML cells express SIRPα, its function has not been investigated in these cells. In this study we aimed to determine the role of the SIRPα in acute myeloid leukemia.

DESIGN AND METHODS

We analyzed the expression of SIRPα, both on mRNA and protein level in AML patients and we further investigated whether the expression of SIRPα on two low SIRPα expressing AML cell lines could be upregulated upon differentiation of the cells. We determined the effect of chimeric SIRPα expression on tumor cell growth and programmed cell death by its triggering with an agonistic antibody in these cells. Moreover, we examined the efficacy of agonistic antibody in combination with established antileukemic drugs.

RESULTS

By microarray analysis of an extensive cohort of primary AML samples, we demonstrated that SIRPα is differentially expressed in AML subgroups and its expression level is dependent on differentiation stage, with high levels in FAB M4/M5 AML and low levels in FAB M0-M3. Interestingly, AML patients with high SIRPα expression had a poor prognosis. Our results also showed that SIRPα is upregulated upon differentiation of NB4 and Kasumi cells. In addition, triggering of SIRPα with an agonistic antibody in the cells stably expressing chimeric SIRPα, led to inhibition of growth and induction of programmed cell death. Finally, the SIRPα-derived signaling synergized with the activity of established antileukemic drugs.

CONCLUSIONS

Our data indicate that triggering of SIRPα has antileukemic effect and may function as a potential therapeutic target in AML.

[Genetic prognostic factors in childhood acute myeloid leukemia]

The survival rate of children and adolescents suffering acute myeloid leukemia (AML) has been significantly improved within the last decades. This has been achieved by a continuously intensified therapy and progress in supportive care to prevent and treat complications. In Germany, the AML-BFM trials 98 (n=413) and 2004 (n=499) enrolled 912 children and adolescents as protocol patients (1998-2010). The 5-year-overall survival was 71±2%. In the previous studies prognosis and subsequent treatment stratification based on morphology, cytochemistry and white blood cell count. Today, the identification of new genetic aberrations in AML enables a genetically determined estimation of prognosis, although treatment response must be considered for treatment stratification. The group with a favorable prognosis summarized AML with t(8;21), inv(16), t(15;17), t(1;11), and AML with normal karyotype and NPM1-mutation (n=253; EFS 74±3%, OS 88±2%). A poor prognosis (HR-group) must be expected in AML with t(4;11), t(5;11), t(6;11), t(6;9), t(7;12), t(9;22), Monosomy 7, combined FLT3/WT1-mutation, and AML with der(12p)-aberration (n=101; EFS 30±5%; OS 56±5%). The intermediate group summarizes all other subgroups especially AML with normal karyotyp, AML with FLT3-ITD or t(9;11) (n=558; EFS 43±2%; OS 64±2%). The validation of the internationally identified, genetically determined prognostic factors within the AML-BFM (Germany) study population will support treatment recommendations.

[GATA1-mutation associated leukemia in children with trisomy 21 mosaic]

Mutations of the hematopoietic transcription factor GATA1 (GATA1s) are pathognomonic in newborn with transient leukemia and children with Down syndrome and myeloid leukemia (ML-DS). Both TL and ML-DS can also occur in children with trisomy 21 mosaic.Between 2002 and 2011, 15 newborns and infants were diagnosed with DS mosaic. 9 of them presented with TL and 8 children suffered from ML-DS; 2 of them with a history of TL. In children without stigmata the special morphology and immunophenotype of blasts triggered the screening for GATA1 mutation and trisomy 21 mosaic.All newborns with TL achieved complete remission (CR). Due to clinical symptoms caused by the leukemic blasts, in 3 children low-dose cytarabine was applied. 1 patient died due to cardiac defect. In all patients GATA 1 s was confirmed. 6 children with ML-DS were initially treated according the AML-BFM protocol. After ML-DS was confirmed, therapy was continued with the intensity reduced schedule according to the ML-DS 2006 protocol. All children are still in CR (follow-up 1.8-7 years, median 2.7 yrs). 2 children with unknown trisomy 21 mosaic were diagnosed as acute megakaryoblastic leukemia (AMKL) and treated according the high risk arm of the AML-BFM 2004 including allogeneic stem cell transplantation in one child). GATA1 mutation was identified retrospectively. Both children are alive in CR.GATA1s associated leukemia has to be excluded in all young children with AMKL (<5 years old) to prevent overtreatment. Treatment with reduced intensity seems sufficient in children trisomy 21 mosaic and ML-DS.

CNS irradiation in pediatric acute myleoid leukemia: equal results by 12 or 18 Gy in studies AML-BFM98 and 2004

BACKGROUND

The impact of preventive central nervous system irradiation (CNS-RT) in childhood acute myeloid leukemia (AML) is still discussed. As results of study AML-BFM87 revealed an increased risk for relapse when CNS-RT was not performed, studies AML-BFM98 and -2004 randomized CNS-RT of 18 or 12 Gy in order to evaluate the efficacy of the lower dose and to reduce late effects.

PROCEDURES

To achieve a power of 80% for non-inferiority (range 11%) 240 patients per group were required. Out of 722 eligible patients, 486 patients <18 years were randomized to receive 12 Gy (n = 249) or 18 Gy (n = 237). Since this was a non-inferiority study, the analysis was performed for patients as treated (12 Gy: n = 252 and 18 Gy: n = 219).

RESULTS

Five-year survival, event-free survival and cumulative incidence of relapse were similar in patients who received 12 or 18 Gy, respectively (82 ± 3% vs. 79 ± 3%, 68 ± 3% vs. 63 ± 3%, and 30 ± 3% vs. 34 ± 3%). The lower limit of the one-sided confidence interval for the -5% difference in 5-years pEFS was 2%. There were six relapses with CNS involvement (one in the 12 Gy, and five in the 18 Gy group).

CONCLUSION

Results demonstrate no disadvantage for patients irradiated with a reduced CNS dose of 12 Gy.

Long term survival in children with acute leukaemia and complications requiring mechanical ventilation

OBJECTIVE

Previous reports have indicated that the short term prognosis for patients with malignant diseases and serious adverse events requiring mechanical ventilation (SAEV) is improving. The purpose of this study was to determine whether these patients can be cured of malignant disease or whether they survive SAEV only to subsequently relapse.

PATIENTS AND METHODS

The authors report the outcome of children with SAEV treated in the multicentre studies ALL-BFM 95 and AML-BFM 98. Data from 1182 patients with acute lymphoblastic leukaemia (ALL) and 334 patients with acute myeloid leukaemia (AML) were analysed. 88 patients (51 ALL and 37 AML) developed SAEV.

RESULTS

The prognosis was almost identical in ALL and AML patients (survival of SAEV patients: 48%, 95% CI 38% to 58%; overall survival after 5 years: 31%, 95% CI 21% to 41%). Prognosis was independent of the time between leukaemia diagnosis and SAEV. Approximately 20% of children who required haemodialysis (n=14) or cardiac resuscitation (n=16) achieved long term survival, but no patient who fulfilled more than three of six identified risk factors (age ≥10 years, high risk leukaemia, C reactive protein ≥150 mg/l, administration of inotropic infusion, cardiac resuscitation and haemodialysis) survived (n=16; 0%, 95% CI 0% to 20%).

CONCLUSIONS

Intensive care improves the short and long term survival of children with leukaemia. 64% (95% CI 50% to 78%) of children with acute leukaemia who survived SAEV achieved long term survival. Prognosis mainly depends on age and leukaemia risk group.

Favorable outcome in infants with AML after intensive first- and second-line treatment: an AML-BFM study group report

Infants <1 year of age have a high prevalence of prognostically unfavorable leukemias and a presumed susceptibility to treatment-related toxicities. A total of 125 infants with acute myeloid leukemia (AML) were treated in studies AML-BFM-98 (n = 59) and -2004 (n = 66). Treatment regimens of both studies were comparable, consisting of intensive induction followed by four courses (mainly high-dose cytarabine and anthracyclines). Allogeneic-hematopoietic stem-cell-transplantation (allo-HSCT) in 1st remission was optional for high-risk (HR) patients. Most infants (120/125=96%) were HR patients according to morphological, cytogenetic/molecular genetic and response criteria. Five-year overall survival was 66 ± 4%, and improved from 61 ± 6% in study-98 to 75 ± 6% in study-2004 (P(logrank) 0.14) and event-free survival rates were 44 ± 6% and 51 ± 6% (P(logrank) 0.66), respectively. Results in HR infants were similar to those of older HR children (1-<2- or 2-<10-year olds, P(logrank) 0.90 for survival). Survival rates of HSCT in 1st remission, initial partial response and after relapse were high (13/14, 2/8 and 20/30 patients, respectively). The latter contributes to excellent 5-year survival after relapse (50±8%). Despite more severe infections and pulmonary toxicities in infants, treatment-related death rate was identical to that of older children (3%). Our data indicate that intensive frontline and relapse AML treatment is feasible in infants, toxicities are manageable, and outcome is favorable.

The role of matched sibling donor allogeneic stem cell transplantation in pediatric high-risk acute myeloid leukemia: results from the AML-BFM 98 study

BACKGROUND

The role of allogeneic stem cell transplantation in post-remission management of children with high-risk acute myeloid leukemia remains controversial. In the multi-center AML-BFM 98 study we prospectively evaluated the impact of allogeneic stem cell transplantation in children with high-risk acute myeloid leukemia in first complete remission.

DESIGN AND METHODS

HLA-typed patients with high-risk acute myeloid leukemia, who achieved first complete remission (n = 247), were included in this analysis. All patients received double induction and consolidation. Based on the availability of a matched-sibling donor, patients were allocated by genetic chance to allogeneic stem cell transplantation (n = 61) or chemotherapy-only (i.e. intensification and maintenance therapy; n = 186). The main analysis was done on an intention-to-treat basis according to this allocation.

RESULTS

Intention-to-treat analysis did not show a significantly different 5-year disease-free survival (49 ± 6% versus 45 ± 4%, P(log rank) = 0.44) or overall survival (68 ± 6% versus 57 ± 4%, P(log rank) = 0.17) between the matched-sibling donor and no-matched-sibling donor groups, whereas late adverse effects occurred more frequently after allogeneic stem cell transplantation (72.5% versus 31.8%, P(Fischer)<0.01). These results were confirmed by as-treated analysis corrected for the time until transplantation (5-year overall survival: 72 ± 8% versus 60 ± 4%, P(Mantel-Byar) 0.21). Subgroup analysis demonstrated improved survival rates for patients with 11q23 aberrations allocated to allogeneic stem cell transplantation (5-year overall survival: 94 ± 6% versus 52 ± 7%, P(log-rank) = 0.01; n = 18 versus 49) in contrast to patients without 11q23 aberrations (5-year overall survival: 58 ± 8% versus 55 ± 5%, P(log-rank) = 0.66).

CONCLUSIONS

Our analyses defined a genetic subgroup of children with high-risk acute myeloid leukemia who benefited from allogeneic stem cell transplantation in the prospective multi-center AML-BFM 98 study. For the remainder of the pediatric high-risk acute myeloid leukemia patients the prognosis was not improved by allogeneic stem cell transplantation, which was, however, associated with a higher rate of late sequelae.

Integrative analysis of type-I and type-II aberrations underscores the genetic heterogeneity of pediatric acute myeloid leukemia

BACKGROUND

Several studies of pediatric acute myeloid leukemia have described the various type-I or type-II aberrations and their relationship with clinical outcome. However, there has been no recent comprehensive overview of these genetic aberrations in one large pediatric acute myeloid leukemia cohort.

DESIGN AND METHODS

We studied the different genetic aberrations, their associations and their impact on prognosis in a large pediatric acute myeloid leukemia series (n=506). Karyotypes were studied, and hotspot regions of NPM1, CEPBA, MLL, WT1, FLT3, N-RAS, K-RAS, PTPN11 and KIT were screened for mutations of available samples. The mutational status of all type-I and type-II aberrations was available in 330 and 263 cases, respectively. Survival analysis was performed in a subset (n=385) treated on consecutive acute myeloid leukemia Berlin-Frankfurt-Munster Study Group and Dutch Childhood Oncology Group treatment protocols.

RESULTS

Genetic aberrations were associated with specific clinical characteristics, e.g. significantly higher diagnostic white blood cell counts in MLL-rearranged, WT1-mutated and FLT3-ITD-positive acute myeloid leukemia. Furthermore, there was a significant difference in the distribution of these aberrations between children below and above the age of two years. Non-random associations, e.g. KIT mutations with core-binding factor acute myeloid leukemia, and FLT3-ITD with t(15;17)(q22;q21), NPM1- and WT1-mutated acute myeloid leukemia, respectively, were observed. Multivariate analysis revealed a 'favorable karyotype', i.e. t(15;17)(q22;q21), t(8;21)(q22;q22) and inv(16)(p13q22)/t(16;16)(p13;q22). NPM1 and CEBPA double mutations were independent factors for favorable event-free survival. WT1 mutations combined with FLT3-ITD showed the worst outcome for 5-year overall survival (22±14%) and 5-year event-free survival (20±13%), although it was not an independent factor in multivariate analysis.

CONCLUSIONS

Integrative analysis of type-I and type-II aberrations provides an insight into the frequencies, non-random associations and prognostic impact of the various aberrations, reflecting the heterogeneity of pediatric acute myeloid leukemia. These aberrations are likely to guide the stratification of pediatric acute myeloid leukemia and may direct the development of targeted therapies.

Abstract 3209: Gene expression micro array analysis of diagnosis and matched relapse pediatric AML samples indicates that immune regulatory pathways and epigenetic factors are involved in disease progression

Due to optimization of induction treatment, approximately 90% of AML pediatric patients achieve a complete remission. However, relapses still occur in 30-40% of patients, with dismal outcome. In order to find new options for targeted treatment, we aim to identify key molecules and signaling pathways involved in the development of relapses. To this end we use gene expression profiling.

Total mRNA of initial diagnosis and matched relapse bone marrow samples (&gt;80% blasts) was obtained from 27 pediatric AML patients and used for Affymetrix HGU 133 plus 2.0 microarrays. For statistical analyses we used BioConductor packages, Significance Analysis of Microarrays (SAM) and BRB Arraytools. Pathway analysis was performed using Ingenuity and Gene Set Enrichment Analysis (GSEA).

Analysis of paired diagnosis and relapse samples revealed large inter-patient differences in the number of genes that were differentially expressed. Unsupervised cluster analysis showed that for 47% of patients the diagnosis and relapse sample cluster next to each other. The remaining paired samples clustered more distant and interestingly the majority of these pairs also showed changes in mutation status of FLT3 or RAS. The former have been described by us to be associated with shorter time to relapse (Bachas et al, Blood, 2010). Pathway analysis of the differentially expressed genes (&gt; 1.5 fold) revealed molecular pathways implicated in cancer, inflammatory disease, hematopoietic development and genetic disorders. Involved biological processes were related to the immune system, nuclear organization and intracellular trafficking.

We performed in silico class prediction and found 31 genes to be differentially expressed and discriminative for diagnosis or relapse samples with an accuracy of more than 80%, as determined by ‘leave-one-out’ cross validation. Of the 31 genes, 29 showed a lowered expression in the relapse sample when compared to the initial diagnosis sample (median intensity ratio diagnosis/relapse = 1.74, range=1.47-2.33, P29th gene=0.032) and 7 of these 29 genes have functions in the maintenance of chromatin structure. Preliminary RT-PCR results confirmed this for an independent set of patient samples. In vitro cytotoxicity experiments on primary patient material using relevant experimental drugs are underway.

In conclusion, we identified genes and pathways that were significantly differentially expressed between diagnosis and relapse samples. The majority of discrimative genes are down-regulated at relapse with an important contribution of genes involved in maintenance of chromatin structure. Our efforts are directed to determine if these findings will be instrumental to design therapies aimed at preventing relapses. Financially supported by the Dutch Cancer Society (VU 2005-3666, J.C.)

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3209. doi:10.1158/1538-7445.AM2011-3209

The state of research into children with cancer across Europe: new policies for a new decade

Overcoming childhood cancers is critically dependent on the state of research. Understanding how, with whom and what the research community is doing with childhood cancers is essential for ensuring the evidence-based policies at national and European level to support children, their families and researchers. As part of the European Union funded EUROCANCERCOMS project to study and integrate cancer communications across Europe, we have carried out new research into the state of research in childhood cancers. We are very grateful for all the support we have received from colleagues in the European paediatric oncology community, and in particular from Edel Fitzgerald and Samira Essiaf from the SIOP Europe office. This report and the evidence-based policies that arise from it come at a important junction for Europe and its Member States. They provide a timely reminder that research into childhood cancers is critical and needs sustainable long-term support.

Characterization of CEBPA mutations and promoter hypermethylation in pediatric acute myeloid leukemia

BACKGROUND

Dysfunctioning of CCAAT/enhancer binding protein α (C/EBPα) in acute myeloid leukemia can be caused, amongst others, by mutations in the encoding gene (CEBPA) and by promoter hypermethylation. CEBPA-mutated acute myeloid leukemia is associated with a favorable outcome, but this may be restricted to the case of double mutations in CEBPA in adult acute myeloid leukemia. In pediatric acute myeloid leukemia, data on the impact of these mutations are limited to one series, and data on promoter hypermethylation are lacking. Our objective was to investigate the characteristics, gene expression profiles and prognostic impact of the different CEBPA aberrations in pediatric acute myeloid leukemia.

DESIGN AND METHODS

We screened a large pediatric cohort (n=252) for CEBPA single and double mutations by direct sequencing, and for promoter hypermethylation by methylation-specific polymerase chain reaction. Furthermore, we determined the gene-expression profiles (Affymetrix HGU133 plus 2.0 arrays) of this cohort (n=237).

RESULTS

Thirty-four mutations were identified in 20 out of the 252 cases (7.9%), including 14 double-mutant and 6 single-mutant cases. CEBPA double mutations conferred a significantly better 5-year overall survival compared with single mutations (79% versus 25%, respectively; P=0.04), and compared with CEBPA wild-type acute myeloid leukemia excluding core-binding factor cases (47%; P=0.07). Multivariate analysis confirmed that the double mutations were an independent favorable prognostic factor for survival (hazard ratio 0.23, P=0.04). The combination of screening for promoter hypermethylation and gene expression profiling identified five patients with silenced CEBPA, of whom four cases relapsed. All cases characteristically expressed T-lymphoid markers. Moreover, unsupervised clustering of gene expression profiles showed a clustering of CEBPA double-mutant and silenced cases, pointing towards a common hallmark of abrogated C/EBPα-functioning in these acute myeloid leukemias.

CONCLUSIONS

We showed the independent favorable outcome of patients with CEBPA double-mutant acute myeloid leukemia in a large pediatric series. This molecular marker may, therefore, improve risk-group stratification in pediatric acute myeloid leukemia. For the first time, CEBPA-silenced cases are suggested to confer a poor outcome in pediatric acute myeloid leukemia, indicating that further investigation of this aberration is needed. Furthermore, clustering of gene expression profiles provided insight into the biological similarities and diversities of the different aberrations in CEBPA in pediatric acute myeloid leukemia.

High BRE expression in pediatric MLL-rearranged AML is associated with favorable outcome

Translocations involving the mixed lineage leukemia (MLL) gene, localized at 11q23, frequently occur in pediatric acute myeloid leukemia (AML). We recently reported differences in prognosis between the different translocation partners, suggesting differences in biological background. To unravel the latter, we used microarrays to generate gene expression profiles of 245 pediatric AML cases, including 53 MLL-rearranged cases. Thereby, we identified a specific gene expression signature for t(9;11)(p22;q23), and identified BRE (brain and reproductive organ expressed) to be discriminative for t(9;11)(p22;q23) (P<0.001) when compared with other MLL subtypes. Patients with high BRE expression showed a significantly better 3-year relapse-free survival (pRFS) (80±13 vs 30±10%, P=0.02) within MLL-rearranged AML cases. Moreover, multivariate analysis identified high BRE expression as an independent favorable prognostic factor within pediatric AML for RFS (HR=0.2, P=0.04). No significant differences were identified for 3-year event-free survival or for 3-year overall survival. Forced expression of BRE did not result in altered cell proliferation, apoptosis or drug sensitivity, which could explain the favorable outcome. In conclusion, overexpression of the BRE gene is predominantly found in MLL-rearranged AML with t(9;11)(p22;q23). Although further investigation for the role of BRE in leukemogenesis and outcome is warranted, high BRE expression is an independent prognostic factor for pRFS in pediatric AML.