Acute leukaemia in children with Down syndrome: a population-based Nordic study

Down syndrome and leukemia: An insight into the disease biology and current treatment options

Children with Down syndrome (DS) have a 10- to 20-fold greater predisposition to develop acute leukemia compared to the general population, with a skew towards myeloid leukemia (ML-DS). While ML-DS is known to be a subtype with good outcome, patients who relapse face a dismal prognosis. Acute lymphocytic leukemia in DS (DS-ALL) is considered to have poor prognosis. The relapse rate is high in DS-ALL compared to their non-DS counterparts. We have a better understanding about the mutational spectrum of DS leukemia. Studies using animal, embryonic stem cell- and induced pluripotent stem cell-based models have shed light on the mechanism by which these mutations contribute to disease initiation and progression. In this review, we list the currently available treatment strategies for DS-leukemias along with their outcome with emphasis on challenges with chemotherapy-related toxicities in children with DS. We focus on the mechanisms of initiation and progression of leukemia in children with DS and highlight the novel molecular targets with greater success in preclinical trials that have the potential to progress to the clinic.

Survival outcomes of myeloid leukemia associated with Down syndrome and de novo acute myeloid leukemia in children: Experience from a single tertiary center in Thailand

Few studies have reported the survival outcomes of myeloid leukemia associated with Down syndrome (DS) in resource-limited countries. This study aimed to compare characteristics and survival outcomes of children with acute myeloid leukemia (AML) between those with and without DS in Thailand. The medical records of AML patients aged 0-15 years treated in a major tertiary center in Southern Thailand between October 1978 and December 2019 were reviewed retrospectively. The overall (OS) and event-free survivals (EFS) rates were calculated using the Kaplan-Meier method. A total of 362 AML patients were included, of which 41 (11.3%) had DS. The mean age at diagnosis of the DS patients was 2.5 ± 1.9 years and most of them (90.2%) were under the age of five. The DS patients had lower initial white blood cell counts and peripheral blasts compared to the non-DS patients. The AML-M7 subtype was more common in the DS than in the non-DS patients (80.5% vs. 9.1%, p < 0.01, respectively). The 5-year OS and EFS rates of the DS patients were lower compared to the non-DS patients (12.9% vs. 20.5%, p = 0.05 and 13.7% vs. 18.4%, p = 0.03, respectively). DS patients had a significantly higher rate of early and treatment-related deaths compared to non-DS patients (30.3% vs. 13.5%, p < 0.01 and 39.4% vs. 19.5%, p = 0.02, respectively). Over the study period, there were a decrease in early death rate and an increase in survival rates of DS patients, which suggests that chemotherapy regimens and supportive care have improved over time.

PEG-asparaginase treatment regimens for acute lymphoblastic leukaemia in children: a network meta-analysis

BACKGROUND

Asparaginase has played a crucial role in the improvement of survival in children with acute lymphoblastic leukaemia (ALL), which is the commonest cancer among children. Survival rates have steadily increased over decades since the introduction of asparaginase to ALL therapy, and overall survival rates reach 90% with the best contemporary protocols. Currently, polyethylene glycolated native Escherichia coli-derived L-asparaginase (PEG-asparaginase) is the preferred first-line asparaginase preparation. Besides its clinical benefits, PEG-asparaginase is well known for severe toxicities. Agreement on the optimal dose, treatment duration, and frequency of administration has never been reached among clinicians.

OBJECTIVES

Primary objective To assess the effect of the number of PEG-asparaginase doses on survival and relapse in children and adolescents with ALL. Secondary objectives To assess the association between the number of doses of PEG-asparaginase and asparaginase-associated toxicities (e.g. hypersensitivity, thromboembolism, pancreatitis and osteonecrosis). To undertake a network meta-analysis at dose-level in order to generate rankings of the number of doses of PEG-asparaginase used in the treatment for ALL, according to their benefits (survival and relapse) and harms (toxicity).

SEARCH METHODS

We searched CENTRAL, PubMed, Embase, Web of Science databases and three trials registers in November 2021, together with reference checking, citation searching and contact with study authors to identify additional studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing different PEG-asparaginase treatment regimens in children and adolescents (< 18 years of age) with first-line ALL treated with multiagent chemotherapy including PEG-asparaginase.

DATA COLLECTION AND ANALYSIS

Using a standardised data collection form, two review authors independently screened and selected studies, extracted data, assessed risk of bias for each outcome using a standardised tool (RoB 2.0) and assessed the certainty of evidence for each outcome using the GRADE approach. Primary outcomes included overall survival, event-free survival and leukaemic relapse. Secondary outcomes included asparaginase-associated toxicities (hypersensitivity, thromboembolism, pancreatitis, sinusoidal obstruction syndrome and osteonecrosis as well as overall asparaginase-associated toxicity). We conducted the review and performed the analyses in accordance with the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions.

MAIN RESULTS

We included three RCTs in the review, and identified an additional four ongoing studies. We judged outcomes of two RCTs to be at low risk of bias in all the Cochrane risk of bias (RoB 2) domains. We rated the remaining study as having some concerns regarding bias. Due to concerns about imprecision, we rated all outcomes as having low- to moderate-certainty evidence.  One study compared intermittent PEG-asparaginase treatment (eight doses of PEG-asparaginase, 1000 IU/m2, intramuscular (IM) administration) versus continuous PEG-asparaginase treatment (15 doses of PEG-asparaginase, 1000 IU/m2, IM) in 625 participants with non-high risk ALL aged 1.0 to 17.9 years. We found that treatment with eight doses probably results in little to no difference in event-free survival compared to treatment with 15 doses (RR 1.01, 95% CI 0.97 to 1.06; moderate-certainty evidence). Compared to treatment with 15 doses, treatment with eight doses may result in either no difference or a slight reduction in hypersensitivity (RR 0.64, 95% CI 0.21 to 1.93; low-certainty evidence), thromboembolism (RR 0.55, 95% CI 0.22 to 1.36; low-certainty evidence) or osteonecrosis (RR 0.68, 95% CI 0.35 to 1.32; low-certainty evidence). Furthermore, we found that treatment with eight doses probably reduces pancreatitis (RR 0.31, 95% CI 0.12 to 0.75; moderate-certainty evidence) and asparaginase-associated toxicity (RR 0.53, 95% CI 0.35 to 0.78; moderate-certainty evidence) compared to treatment with 15 doses. One study compared low-risk standard treatment with additional PEG-asparaginase (six doses, 2500 IU/m2, IM) versus low-risk standard treatment (two doses, 2500 IU/m2, IM) in 1857 participants aged one to nine years old with standard low-risk ALL. We found that, compared to treatment with two doses, treatment with six doses probably results in little to no difference in overall survival (RR 0.99, 95% CI 0.98 to 1.00; moderate-certainty evidence) and event-free survival (RR 1.01, 95% CI 0.99 to 1.04; moderate-certainty evidence), and may result in either no difference or a slight increase in osteonecrosis (RR 1.65, 95% CI 0.91 to 3.00; low-certainty evidence). Furthermore, we found that treatment with six doses probably increases hypersensitivity (RR 12.05, 95% CI 5.27 to 27.58; moderate-certainty evidence), pancreatitis (RR 4.84, 95% CI 2.15 to 10.85; moderate-certainty evidence) and asparaginase-associated toxicity (RR 4.49, 95% CI 3.05 to 6.59; moderate-certainty evidence) compared to treatment with two doses. One trial compared calaspargase (11 doses, 2500 IU/m2, intravenous (IV)) versus PEG-asparaginase (16 doses, 2500 IU/m2, IV) in 239 participants aged one to 21 years with standard- and high-risk ALL and lymphoblastic lymphoma. We found that treatment with 11 doses of calaspargase probably results in little to no difference in event-free survival compared to treatment with 16 doses of PEG-asparaginase (RR 1.06, 95% CI 0.97 to 1.16; moderate-certainty evidence). However, treatment with 11 doses of calaspargase probably reduces leukaemic relapse compared to treatment with 16 doses of PEG-asparaginase (RR 0.32, 95% CI 0.12 to 0.83; moderate-certainty evidence). Furthermore, we found that treatment with 11 doses of calaspargase results in either no difference or a slight reduction in hypersensitivity (RR 1.17, 95% CI 0.64 to 2.13; low-certainty evidence), pancreatitis (RR 0.85, 95% CI 0.47 to 1.52; low-certainty evidence), thromboembolism (RR 0.83, 95% CI 0.48 to 1.42; low-certainty evidence), osteonecrosis (RR 0.63, 95% CI 0.15 to 2.56; low-certainty evidence) and asparaginase-associated toxicity (RR 1.00, 95% CI 0.71 to 1.40; low-certainty evidence) compared to treatment with 16 doses of PEG-asparaginase.

AUTHORS' CONCLUSIONS

We were not able to conduct a network meta-analysis, and could not draw clear conclusions because it was not possible to rank the interventions. Overall, we found that different numbers of doses of PEG-asparaginase probably result in little to no difference in event-free survival across all studies. In two studies, we found that a higher number of PEG-asparaginase doses probably increases pancreatitis and asparaginase-associated toxicities.

Participation, challenges and needs in children with down syndrome during cancer treatment at hospital: a qualitative study of parents' experiences

Background

Studies report that it can be challenging to assess and treat side-effects and symptoms among children who have impairments and difficulties in expressing their needs. Children with Down syndrome have an increased vulnerability and an increased risk for contracting leukaemia. There is sparse knowledge about the parental experience of how treatment and side-effects affect children with Down syndrome with leukaemia, as well as the role of participation during treatment.

Purpose

This study aimed to explore the perceptions of parents of children with Down syndrome and leukaemia regarding their child's treatment, side effects and participation during hospital care.

Methods

A qualitative study design was used, and interviews were conducted with a semi-structured interview-guide. Fourteen parents of 10 children with Down syndrome and acute lymphoblastic leukaemia from Sweden and Denmark, 1-18 years of age, participated. All children had completed therapy or had a few months left before the end of treatment. Data was analysed according to qualitative content analysis.

Results

Four sub-themes were identified: (1) Continuously dealing with the child's potential susceptibility; (2) Confidence and worries regarding decisions related to treatment regulation; (3) Challenges in communication, interpretation, and participation; and (4) Facilitating participation by adapting to the child's behavioural and cognitive needs. The sub-themes were bound together in an overarching theme, which expressed the core perception "Being the child's spokesperson to facilitate the child's participation during treatment". The parents expressed this role as self-evident to facilitate communication regarding the needs of the child, but also regarding how the cytotoxic treatment affected the vulnerable child. Parents conveyed the struggle to ensure the child's right to receive optimal treatment.

Conclusion

The study results highlight parental challenges regarding childhood disabilities and severe health conditions, as well as communication and ethical aspects regarding to act in the best interests of the child. Parents played a vital role in interpreting their child with Down syndrome. Involving parents during treatment enables a more accurate interpretation of symptoms and eases communication and participation. Still, the results raise questions regarding issues related to building trust in healthcare professionals in a context where medical, psychosocial and ethical dilemmas are present.

Dissecting stepwise mutational impairment of megakaryopoiesis in a model of Down syndrome-associated leukemia

Individuals with Down syndrome (DS) have more than 100-fold increased risk of acute megakaryoblastic leukemia (AMKL), but its pathogenesis is poorly understood. In this issue of the JCI, Arkoun et al. engineered stepwise DS-AMKL-associated mutations in GATA1, MPL, and SMC3 in human induced pluripotent stem cell (iPSC) clones from individuals with DS to dissect how each mutation affects gene expression control and megakaryocytic differentiation. The authors showed that the mutations cooperatively promote progression from transient myeloproliferative disorder to DS-AMKL. This study highlights the importance of mutation order and context in the perturbations of transcriptional and differentiation pathways involved in the evolution of hematologic malignancies, which will be critical for the development of preventative and therapeutic interventions.

Clinical and biological aspects of myeloid leukemia in Down syndrome

Children with Down syndrome are at an elevated risk of leukemia, especially myeloid leukemia (ML-DS). This malignancy is frequently preceded by transient abnormal myelopoiesis (TAM), which is self-limited expansion of fetal liver-derived megakaryocyte progenitors. An array of international studies has led to consensus in treating ML-DS with reduced-intensity chemotherapy, leading to excellent outcomes. In addition, studies performed in the past 20 years have revealed many of the genetic and epigenetic features of the tumors, including GATA1 mutations that are arguably associated with all cases of both TAM and ML-DS. Despite these advances in understanding the clinical and biological aspects of ML-DS, little is known about the mechanisms of relapse. Upon relapse, patients face a poor outcome, and there is no consensus on treatment. Future studies need to be focused on this challenging aspect of leukemia in children with DS.

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.

Epidemiology of Acute Leukemia among Children with Down Syndrome in Korea

Purpose

Children with Down syndrome (DS) show a higher risk of acute leukemia than those without DS. In this study, we investigated the nationwide incidence of acute leukemia among children with DS and compared their epidemiologic characteristics with those of children with acute leukemia but without DS.

Materials and Methods

Using the National Health Insurance Service database, we selected patients with acute leukemia aged 0–19 years at diagnosis between 2007 and 2016.

Results

Among the 4,697 children with acute leukemia, 54 (1.1%) had DS. The median incidence rate of leukemia with DS by year was 1.3% (range, 0.2% to 2.0%). Sixteen patients with acute lymphoblastic leukemia (ALL; 29.6%) and 36 with acute myeloid leukemia (AML; 66.7%) had DS. The DS group showed younger age at diagnosis than the non-DS group, and diagnosis of AML was more frequent in the DS group than in the non-DS group (3 years vs. 9 years, p < 0.001; 66.7% vs. 32.4%, p < 0.001, respectively). The 5-year overall survival was comparable between the DS and non-DS groups (88.0% vs. 81.9%, p=0.375). Among all the Koreans born between 2007 and 2008, the incidences of acute leukemia, ALL, and AML were 49.25, 20.75, and 163.38 times higher, respectively, in the DS group than in the non-DS group.

Conclusion

Our findings support the fact that the incidence of acute leukemia is higher among patients with DS than among those without DS in Korea. However, the DS and non-DS groups in this study had a comparable overall survival rate.

High-dose AraC is Essential for the Treatment of ML-DS Independent of Post-Induction MRD: Results of COG AAML1531

Myeloid leukemia in children with Down syndrome (ML-DS) is associated with young age and somatic GATA1 mutations. Due to high event-free survival (EFS) and hypersensitivity of the leukemic blasts to chemotherapy, the prior Children's Oncology Group protocol ML-DS protocol (AAML0431), reduced overall treatment intensity but lacking risk stratification, retained the high-dose cytarabine course (HD-AraC), which was highly associated with infectious morbidity. Despite high EFS of ML-DS, survival for those who relapse is rare. AAML1531 introduced therapeutic risk stratification based on the previously identified prognostic factor, measurable residual disease (MRD) at the end of the first induction course. Standard risk (SR) patients were identified by negative MRD using flow cytometry (<0.05%) and did not receive the historically administered HD-AraC course. Interim analysis of 114 SR patients revealed a 2-year EFS of 85.6% (95% confidence interval (CI), 75.7-95.5%), which was significantly lower than for MRD-negative patients treated with HD-AraC on AAML0431 (p=0.0002). Overall survival at 2 years was 91.0% (95% CI 83.8%-95.0%). Twelve SR patients relapsed, mostly within one year from study entry and had a 1-year OS of 16.7% (95% CI 2.7% - 41.3%). Complex karyotypes were more frequent in SR patients who relapsed compared to those who did not (36% vs. 9%; p=0.0248). MRD by error-corrected sequencing of GATA1 mutations was piloted in 18 SR patients and detectable in 60% who relapsed vs. 23% who did not (p=0.2682). Patients with SR ML-DS had worse outcomes without HD-AraC after risk classification based on flow cytometric MRD. ClinicalTrials.gov NCT02521493.

Number of siblings and survival from childhood leukaemia: a national register-based cohort study from Sweden

BACKGROUND

Previous studies suggest worse leukaemia survival for children with siblings, but the evidence is sparse, inconsistent and does not consider clinical factors. We explored the associations between number of siblings in the household, birth order and survival from childhood acute lymphoid leukaemia (ALL) and acute myeloid leukaemia (AML).

METHODS

In this nationwide register-based study we included all children aged 1-14, diagnosed with ALL and AML between 1991-mid-2015 in Sweden (n = 1692). Using Cox regression models, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs) according to number of siblings and birth order, adjusting for known prognostic and sociodemographic factors.

RESULTS

A tendency towards better ALL survival among children with one, or ≥2, siblings was observed, adjHRs (95% CI): 0.73 (0.49-1.10) and 0.63 (0.40-1.00), respectively. However, this was mainly limited to children with low risk profiles. An indication of better AML survival among children with siblings was seen, adjHRs (95% CI) 0.68 (0.36-1.29) and 0.71 (0.34-1.48) but diminished after adjusting for birth order.

CONCLUSION

Our results do not support previous findings that a larger number of siblings is associated with poorer survival. Inconsistencies might be explained by underlying mechanisms that differ between settings, but chance cannot be ruled out.

Prevalence of Common Disease Conditions in a Large Cohort of Individuals With Down Syndrome in the United States

Purpose

Given the current life expectancy and number of individuals living with Down syndrome (DS), it is important to learn common occurrences of disease conditions across the developmental lifespan. This study analyzed data from a large cohort of individuals with DS in an effort to better understand these disease conditions, inform future screening practices, tailor medical care guidelines, and improve utilization of health care resources.

Methods

This retrospective, descriptive study incorporated up to 28 years of data, compiled from 6078 individuals with DS and 30,326 controls matched on age and sex. Data were abstracted from electronic medical records within a large Midwestern health system.

Results

In general, individuals with DS experienced higher prevalence of testicular cancer, leukemias, moyamoya disease, mental health conditions, bronchitis and pneumonia, gastrointestinal conditions, thyroid disorder, neurological conditions, atlantoaxial subluxation, osteoporosis, dysphagia, diseases of the eyes/adnexa and of the ears/mastoid process, and sleep apnea, relative to matched controls. Individuals with DS experienced lower prevalence of solid tumors, heart disease conditions, sexually transmitted diseases, HIV, influenza, sinusitis, urinary tract infections, and diabetes. Similar rates of prevalence were seen for lymphomas, skin melanomas, stroke, acute myocardial infarction, hepatitis, cellulitis, and osteoarthritis.

Conclusions

While it is challenging to draw a widespread conclusion about comorbidities in individuals with Down syndrome, it is safe to conclude that care for individuals with DS should not automatically mirror screening, prevention, or treatment guidelines for the general U.S. population. Rather, care for those with DS should reflect the unique needs and common comorbidities of this population.

Treatment outcomes in children with Acute lymphoblastic leukemia with versus without coexisting Down's syndrome: A systematic review and meta-analysis

BACKGROUND

Down syndrome (DS) also known as Trisomy 21, is a chromosomal disorder affecting approximately 1 in 732newborns annually in the United States. Children with DS are more likely to develop acute lymphoblastic leukemia (ALL). For the management of pediatric ALL, different treatment protocols have been set up since years. However, ALL children with coexisting DS have shown to have increased therapy-related toxicities compared to those without DS. Therefore, in this study, we aimed to systematically analyze the treatment outcomes in acute ALL children with versus without coexisting DS.

METHODS

Electronic databases including the Web of Science, EMBASE, Cochrane Central, MEDLINE, http://www.ClinicalTrials.gov, and Google scholar were searched for publications reporting treatment related outcomes in ALL children with versus without co-existing DS. Several treatment protocols were used accordingly. This study had a long-term follow-up time period ranging from 5 to 10 years. The RevMan 5.3 software was used to carry out this analysis. Odds ratios (OR) with 95% confidence intervals (CI) were used to represent the results post analysis.

RESULTS

A total number of 31,476 children with ALL enrolled between the years 1981 and 2011 were included. Among the total number of children with ALL, 1303 had coexisting DS. Our results showed that event-free survival was similar in ALL children with versus without DS (odds ratio [OR]: 1.34, 95% confidence interval [CI]: 0.51-3.50; P = .55). Overall mortality (OR: 1.63, 95% CI: 0.86-3.10; P = .13) and participants who achieved clinical remission (OR: 1.04, 95% CI: 0.12-9.29; P = .97) were also similarly manifested. However, treatment-related mortality (OR: 4.29, 95% CI: 2.90-6.36; P = .00001) and induction failure (OR: 2.77, 95% CI: 1.08-7.07; P = .03) were significantly higher in the DS group. Also, total (OR: 1.38, 95% CI: 1.02-1.88; P = .04) and bone marrow relapses (OR: 1.29, 95% CI: 1.00-1.67; P = .05) were significantly higher in ALL children with DS. Nevertheless, central nervous system relapse (OR: 1.15, 95% CI: 0.60-2.20; P = .67), testicular relapse (OR: 0.84, 95% CI: 0.38-1.85; P = .87), and other relapses (OR: 1.12, 95% CI: 0.27-4.62; P = .88) were not significantly different when these outcomes were separately analyzed.

CONCLUSION

Based on this analysis of the treatment outcomes in ALL children with versus without DS, event-free survival, overall mortality, and patients who achieved clinical remission were similar during this long-term follow-up time period. However, due to the significantly higher treatment-related mortality, induction failure, and certain relapses in ALL children with DS, new guidelines might have to focus on reconsidering or modifying treatment regimens for ALL children with DS.

Characteristics and survival of children with acute leukemia with Down syndrome or other birth defects in New York State

BACKGROUND

Acute lymphocytic leukemia (ALL) and acute myeloid leukemia (AML) among DS children have been studied extensively using data from clinical trials or institutional reports. The purpose of this study was to link population-based cancer and birth defects data to evaluate characteristics and survival of children with acute leukemia according to the presence of DS or other birth defects.

METHODS

ALL and AML cases diagnosed between 1983 and 2012 among children aged 0-14 years were obtained from the New York State Cancer Registry. Birth defect status (DS, other birth defects, or no birth defects) was determined by linking with birth defects data. Associations between birth defect status and demographic characteristics were evaluated using contingency table analysis. Ten-year survival was calculated by birth defect status and other potential prognostic factors. Cox proportional hazards regression analysis was also performed.

RESULTS

Among 2941 ALL children, 1.6% had DS, 3.8% had other birth defects, and 94.5% had no birth defects. Birth defect status was significantly associated with age at ALL diagnosis. Survivals were similar among three groups. Among 563 AML children, 11.0% had DS, 6.0% had other birth defects, and 83.0% had no birth defects. Children with DS were more likely to be diagnosed with AML at a younger age and showed the best survival.

CONCLUSION

Age at leukemia diagnosis was significantly associated with the birth defect status. Comparable survival was observed for ALL children. However, AML children with DS demonstrated superior survival compared to children with other birth defects or no birth defects.

Outcome of children and adolescents with Down syndrome treated on Dana-Farber Cancer Institute Acute Lymphoblastic Leukemia Consortium protocols 00-001 and 05-001

BACKGROUND

Children and adolescents with Down syndrome (DS) and acute lymphoblastic leukemia (ALL) are reported to have increased relapse rates and therapy-related mortality (TRM). Treatment regimens for DS-ALL patients often include therapy modifications. Dana-Farber Cancer Institute (DFCI) ALL Consortium protocols have used same risk-stratified treatment for patients with and without DS.

PROCEDURES

We compared clinical and outcome data of DS (n = 38) and non-DS (n = 1,248) patients enrolled on two consecutive DFCI ALL trials 00-001 (2000-2004) and 05-001 (2005-2011) with similar risk adapted therapy regardless of DS status.

RESULTS

There was no difference in demographic or presenting clinical features between two groups except absence of T-cell phenotype and lower frequency of hyperdiploidy in DS-ALL group. All DS-ALL patients achieved complete remission; four relapsed and one subsequently died. There was no TRM in DS-ALL patients. DS-ALL patients had significantly higher rates of mucositis (52% vs. 12%, p < 0.001), non-CNS thrombosis (18% vs. 8%; p = 0.036), and seizure (16% vs. 5%, p = 0.010). Compared to non-DS-ALL patients, DS-ALL patients had a higher incidence of infections during all therapy phases. The 5-year event-free and overall survival rates of DS-ALL patients were similar to non-DS-ALL patients (91% [95% confidence interval (CI), 81-100] vs. 84% [95% CI, 82-86]; 97% [95% CI, 92-100] vs. 91% [95% CI, 90-93]).

CONCLUSION

The low rates of relapse and TRM indicate that uniform risk-stratified therapy for DS-ALL and non-DS-ALL patients on DFCI ALL Consortium protocols was safe and effective, although the increased rate of toxicity in the DS-ALL patients highlights the importance of supportive care during therapy.

Late mortality and morbidity among long-term leukemia survivors with Down syndrome: A nationwide population-based cohort study

BACKGROUND

Late health consequences of treatment for childhood leukemia are well documented. Although individuals with Down syndrome (DS) have a substantially increased risk of leukemia, information on late effects in this group is almost nonexistent. The aim of this study was to evaluate the mortality and morbidity among 5-year leukemia survivors with DS.

PROCEDURE

We compared 5-year leukemia survivors with leukemia-free individuals with DS. All individuals born with DS in Denmark between 1960 and 2007 and in Sweden between 1973 and 2009 were included. Long-term morbidity was estimated by comparing hospitalization rates between survivors and leukemia-free individuals.

RESULTS

In total, we found 6,705 individuals with DS, 84 of whom were 5-year survivors of leukemia. Survivors had a higher risk of death (hazard ratio [HR] 5.9; 95% confidence interval [CI]: 2.7-13) compared with leukemia-free individuals. All deaths (n = 7) among 5-year leukemia survivors were due to relapse. Survivors had a higher hospitalization rate (HR 4.4; 95% CI: 3.1-6.2). However, most of these hospitalizations were due to relapse. Censoring individuals who either had a relapse or were being treated for a relapse more than 5 years from the initial diagnosis (n = 9) attenuated the association (HR 1.4; 95% CI: 1.0-2.1).

CONCLUSION

In this study, we found that relapse was the main reason for death and hospitalization among leukemia survivors with DS, and not late effects. These results are reassuring for individuals treated for DS associated with leukemia and their parents.

Down syndrome associated childhood myeloid leukemia with yet unreported acquired chromosomal abnormalities and a new potential adverse marker: dup(1)(q25q44)

Background

Children with constitutional trisomy 21, i.e. Down syndrome (DS, OMIM #190685) have a 10 to 20-fold increased risk for a hematopoietic malignancy. They may suffer from acute lymphoblastic leukemia or acute myeloid leukemia (AML). AML referred to as myeloid leukemia of Down syndrome (ML-DS) is observed especially after birth at an early gestational age and characterized by enhanced white blood cell count, failure of spontaneous remission, liver fibrosis or liver dysfunction, and is significantly associated with early death. There are only few studies yet focusing on the clonal cytogenetic changes during evolution of ML-DS.

Case presentation

In a 1.4-year-old boy with DS an immunophenotype consistent with AML-M1 according to French-American-British (FAB) classification was diagnoses. Cytogenetic and molecular cytogenetic analyses revealed, besides constitutional free trisomy 21, an unbalanced translocation as der(16)t(1;16)(q25.3;q24), plus a balanced translocation t(3;20)(q25;q13.1). A poor clinical outcome was observed here.

Conclusions

To the best of our knowledge, an ML-DS case associated with identical acquired chromosomal abnormalities was not previously reported. Our findings suggest that especially partial trisomy 1q25 to 1q44 may be indicative for a poor prognosis in ML-DS.

Treatment results in children with myeloid leukemia of Down syndrome in Saudi Arabia: A multicenter SAPHOS leukemia group study

Despite the high incidence of Down syndrome (DS) in Arab countires, the incidence and outcomes of myeloid leukemia of DS (ML-DS) have not been studied. We evaluated 206 pediatric acute myeloid leukemia (AML) patients diagnosed between 2005 and 2012 and identified 31 (15%) ML-DS. The incidence of ML-DS was 48 per 100,000 compared to 0.6 per 100,000 for AML in non-DS children. Thus, patients with DS had 80-fold increased risk of ML-DS compared to AML in non-DS children. The median age at diagnosis was 1.8 years, male/female ratio was 1.2, majority (84%) of patients had FAB-M7 subtype, and the cytogenetic abnormalities were normal karyotype (constitutional trisomy 21) in 48%, additional trisomy in 23%, and other aberrations in 29%. Complete remission, cumulative incidences of relapse (CIR), toxic-death, and 5-year event-free survival (EFS) rates were 96.8%, 19.4%, 13.1%, and 67.7±8.4%; respectively. In the present study, multivariate analysis revealed favorable outcome (5-year EFS 86.7±8.8%) for patients with normal karyotype. The incidence and clinical characteristics of ML-DS in Saudi patients were comparable to other reports. However, there is a need to optimize risk stratification and treatment intensity to reduce CIR and toxic death rates to further improve outcomes of patients with ML-DS.

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

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

A Comprehensive Review of Pediatric Tumors and Associated Cancer Predisposition Syndromes

An understanding of the role of inherited cancer predisposition syndromes in pediatric tumor diagnoses continues to develop as more information is learned through the application of genomic technology. Identifying patients and their relatives at an increased risk for developing cancer is an important step in the care of this patient population. The purpose of this review is to highlight various tumor types that arise in the pediatric population and the cancer predisposition syndromes associated with those tumors. The review serves as a guide for recognizing genes and conditions to consider when a pediatric cancer referral presents to the genetics clinic.

Genetic Polymorphisms Associated to Folate Transport as Predictors of Increased Risk for Acute Lymphoblastic Leukemia in Mexican Children

Acute lymphoblastic leukemia (ALL) is a frequent neoplasia occurring in children. The most commonly used drug for the treatment of ALL is methotrexate (MTX), an anti-folate agent. Previous studies suggest that folate transporters play a role in ALL prognosis and that genetic polymorphism of genes encoding folate transporters may increase the risk of ALL. Therefore, the main goal of this study was to determine the associations among six genetic polymorphisms in four genes related with the folate transporter pathway to determine a relationship with the occurrence of ALL in Mexican children. A case-control study was performed in 73 ALL children and 133 healthy children from Northern and Northwestern Mexico. COL18A1 (rs2274808), SLC19A1 (rs2838956), ABCB1 (rs1045642 and rs1128503), and ABCC5 (rs9838667 and rs3792585). Polymorphisms were assayed through qPCR. Our results showed an increased ALL risk in children carrying CT genotype (OR = 2.55, CI 95% 1.11–5.83, p = 0.0001) and TT genotype (OR = 21.05, CI 95% 5.62–78.87, p < 0.0001) of COL18A1 rs2274808; in SLC19A1 rs2838956 AG carriers (OR = 44.69, CI 95% 10.42–191.63, p = 0.0001); in ABCB1 rs1045642 TT carriers (OR = 13.76, CI 95% 5.94–31.88, p = 0.0001); in ABCC5 rs9838667 AC carriers (OR = 2.61, CI 95% 1.05–6.48, p < 0.05); and in ABCC5 rs3792585 CC carriers (OR = 9.99, CI 95% 3.19–31.28, p = 0.004). Moreover, several combinations of genetic polymorphisms were found to be significantly associated with a risk for ALL. Finally, two combinations of ABCC5 polymorphisms resulted in protection from this neoplasia. In conclusion, certain genetic polymorphisms related to the folate transport pathway, particularly COL18A1 rs2274808, SLC19A1 rs2838956, ABCB1 rs1045642, and ABCC5 rs3792585, were associated with an increased risk for ALL in Mexican children.

The biology, pathogenesis and clinical aspects of acute lymphoblastic leukemia in children with Down syndrome

Children with Down syndrome (DS) are at a 20-fold increased risk for acute lymphoblastic leukemia (DS-ALL). Although the etiology of this higher risk of developing leukemia remains largely unclear, the recent identification of CRLF2 (cytokine receptor like factor 2) and JAK2 mutations and study of the effect of trisomy of Hmgn1 and Dyrk1a (dual-specificity tyrosine phosphorylation-regulated kinase 1A) on B-cell development have shed significant new light on the disease process. Here we focus on the clinical features, biology and genetics of ALL in children with DS. We review the unique characteristics of DS-ALL on both the clinical and molecular levels and discuss the differences in treatments and outcomes in ALL in children with DS compared with those without DS. The identification of new biological insights is expected to pave the way for novel targeted therapies.

Hematopoietic Stem Cells from Ts65Dn Mice Are Deficient in the Repair of DNA Double-Strand Breaks

Down syndrome (DS) is a genetic disorder caused by the presence of an extra partial or whole copy of chromosome 21. In addition to musculoskeletal and neurodevelopmental abnormalities, children with DS exhibit various hematologic disorders and have an increased risk of developing acute lymphoblastic leukemia and acute megakaryocytic leukemia. Using the Ts65Dn mouse model, we investigated bone marrow defects caused by trisomy for 132 orthologs of the genes on human chromosome 21. The results showed that, although the total bone marrow cellularity as well as the frequency of hematopoietic progenitor cells (HPCs) was comparable between Ts65Dn mice and their age-matched euploid wild-type (WT) control littermates, human chromosome 21 trisomy led to a significant reduction in hematopoietic stem cell (HSC) numbers and clonogenic function in Ts65Dn mice. We also found that spontaneous DNA double-strand breaks (DSBs) were significantly increased in HSCs from the Ts65Dn mice, which was correlated with the significant reduction in HSC clonogenic activity compared to those from WT controls. Moreover, analysis of the repair kinetics of radiation-induced DSBs revealed that HSCs from Ts65Dn mice were less proficient in DSB repair than the cells from WT controls. This deficiency was associated with a higher sensitivity of Ts65Dn HSCs to radiation-induced suppression of HSC clonogenic activity than that of euploid HSCs. These findings suggest that an additional copy of genes on human chromosome 21 may selectively impair the ability of HSCs to repair DSBs, which may contribute to DS-associated hematological abnormalities and malignancies.

Anthracycline-Related Cardiotoxicity in Patients with Acute Myeloid Leukemia and Down Syndrome: A Literature Review

Pediatric patients with Down syndrome (DS) are at an increased risk of developing certain cancers. Specifically, patients with DS have a reported 10-20-fold increased risk of developing acute myeloid leukemia (AML). Anthracycline-based treatment regimens achieve good results in patients with DS and AML. It has been proposed that DS status constitutes a risk factor for the cardiotoxicity associated with the use of anthracyclines in the pediatric setting. However, published evidence pointing toward an increased risk of cardiotoxicity in patients with DS is relatively scarce and conflictive. This concise review compiles literature relating to the incidence of anthracycline-related cardiotoxicity in pediatric patients with DS. In general, reports from trials using anthracyclines at the maximum recommended dose showed increases in the incidence of anthracycline-related cardiotoxicity in patients with DS in comparison with trials that used anthracyclines at reduced doses. Evidence from the literature suggests that patients with DS can achieve favorable therapeutic outcomes after receiving treatment with reduced doses of anthracyclines to minimize the potential for cardiotoxicity. Further prospective trials, along with the available evidence, would assist the design of treatment protocols for patients with pediatric leukemias and DS.

Acute Megakaryoblastic Leukemia with t(1;22) Mimicking Neuroblastoma in an Infant

Acute megakaryoblastic leukemia (AMKL) with t(1;22) (p13;q13) is an extremely rare subtype of acute myeloid leukemia that is almost always described in infants. t(1;22) (p13;q13)-positive AMKL with extramedullary infiltration has been previously reported only once in the literature. Herein, we report a 3-month-old infant presenting with a pelvic mass and pancytopenia suggesting neuroblastoma. Bone marrow evaluation revealed t(1;22)-positive AMKL that responded well to a regimen containing high-dose cytarabine.

Down syndrome preleukemia and leukemia

Children with Down syndrome (DS) and acute leukemias acute have unique biological, cytogenetic, and intrinsic factors that affect their treatment and outcome. Myeloid leukemia of Down syndrome (ML-DS) is associated with high event-free survival (EFS) rates and frequently preceded by a preleukemia condition, the transient abnormal hematopoiesis (TAM) present at birth. For acute lymphoblastic leukemia (ALL), their EFS and overall survival are poorer than non-DS ALL, it is important to enroll them on therapeutic trials, including relapse trials; investigate new agents that could potentially improve their leukemia-free survival; and strive to maximize the supportive care these patients need.

Prognosis and management of acute myeloid leukemia in patients with Down syndrome

Children with Down syndrome (DS) are at a substantially increased risk to develop acute myeloid leukemia (AML). This increase in incidence is tempered, however, by favorable overall survival rates of approximately 80%, whereas survival for non-DS children with similar leukemic subtypes is <35%. In this review, the clinical studies that have contributed to this overall high survival will be presented and their individual successes will be discussed. Important issues including intensity of treatment regimens, the role of bone marrow transplants and prognostic indicators will be reviewed. In particular, the roles of high- vs low- vs very low-dose cytarabine will be discussed, as well as potential therapeutic options in the future and the direction of the field over the next 5 years. In summary, children with DS and AML should be treated with a moderate-intensity cytarabine-based regimen with curative intent.

Clinical and genetic features of pediatric acute lymphoblastic leukemia in Down syndrome in the Nordic countries

Background

Children with Down syndrome (DS) have an increased risk for acute lymphoblastic leukemia (ALL). Although previous studies have shown that DS-ALL differs clinically and genetically from non-DS-ALL, much remains to be elucidated as regards genetic and prognostic factors in DS-ALL.

Methods

To address clinical and genetic differences between DS-ALL and non-DS-ALL and to identify prognostic factors in DS-ALL, we ascertained and reviewed all 128 pediatric DS-ALL diagnosed in the Nordic countries between 1981 and 2010. Their clinical and genetic features were compared with those of the 4,647 B-cell precursor (BCP) ALL cases diagnosed during the same time period.

Results

All 128 DS-ALL were BCP ALL, comprising 2.7% of all such cases. The 5-year event-free survival (EFS) and overall survival (OS) were significantly (P = 0.026 and P = 0.003, respectively) worse for DS-ALL patients with white blood cell counts ≥50 × 10⁹/l. The age distributions varied between the DS and non-DS cases, with age peaks at 2 and 3 years, respectively; none of the DS patients had infant ALL (P = 0.029). The platelet counts were lower in the DS-ALL group (P = 0.005). Abnormal karyotypes were more common in non-DS-ALL (P < 0.0001), and there was a significant difference in the modal number distribution, with only 2% high hyperdiploid DS-ALL cases (P < 0.0001). The 5-year EFS and 5-year OS were significantly worse for DS-ALL (0.574 and 0.691, respectively) compared with non-DS-ALL (0.783 and 0.894, respectively) in the NOPHO ALL-1992/2000 protocols (P < 0.001).

Conclusions

The present study adds further support for genetic and clinical differences between DS-ALL and non-DS-ALL.

How I treat ALL in Down's syndrome: pathobiology and management

Children with Down syndrome are at high risk for developing B-cell precursor acute lymphoblastic leukemia (DS-ALL) associated with poor outcome due to both a high relapse rate and increased treatment-related mortality (TRM) from infections. Biologically, these heterogeneous leukemias are characterized by under-representation of the common cytogenetic subgroups of childhood ALL and overrepresentation of CRLF2-IL7R-JAK-STAT activating genetic aberrations. Although relapse is the major determinant of poor outcomes in this population, de-escalation of chemotherapy intensity might be feasible in the 10% to 15% DS-ALL patients with ETV6-RUNX1 or high hyperdipoidy in whom TRM is the major limiting event. As infection-associated TRM occurs during all treatment phases, including the maintenance period, increased surveillance and supportive care is required throughout therapy. Improvement in outcome will require better understanding of the causes of treatment failure and TRM, incorporation of new therapies targeting the unique biological properties of DS-ALL, and enhanced supportive care measures to reduce the risk of infection-related TRM. To facilitate these goals, an international collaboration plans to establish a prospective DS-ALL registry and develop specific supportive care recommendations for this at-risk population.

Acute lymphoblastic leukemia in children with Down syndrome: a retrospective analysis from the Ponte di Legno study group

Children with Down syndrome (DS) have an increased risk of B-cell precursor (BCP) acute lymphoblastic leukemia (ALL). The prognostic factors and outcome of DS-ALL patients treated in contemporary protocols are uncertain. We studied 653 DS-ALL patients enrolled in 16 international trials from 1995 to 2004. Non-DS BCP-ALL patients from the Dutch Child Oncology Group and Berlin-Frankfurt-Münster were reference cohorts. DS-ALL patients had a higher 8-year cumulative incidence of relapse (26% ± 2% vs 15% ± 1%, P < .001) and 2-year treatment-related mortality (TRM) (7% ± 1% vs 2.0% ± <1%, P < .0001) than non-DS patients, resulting in lower 8-year event-free survival (EFS) (64% ± 2% vs 81% ± 2%, P < .0001) and overall survival (74% ± 2% vs 89% ± 1%, P < .0001). Independent favorable prognostic factors include age <6 years (hazard ratio [HR] = 0.58, P = .002), white blood cell (WBC) count <10 × 10(9)/L (HR = 0.60, P = .005), and ETV6-RUNX1 (HR = 0.14, P = .006) for EFS and age (HR = 0.48, P < .001), ETV6-RUNX1 (HR = 0.1, P = .016) and high hyperdiploidy (HeH) (HR = 0.29, P = .04) for relapse-free survival. TRM was the major cause of death in ETV6-RUNX1 and HeH DS-ALLs. Thus, while relapse is the main contributor to poorer survival in DS-ALL, infection-associated TRM was increased in all protocol elements, unrelated to treatment phase or regimen. Future strategies to improve outcome in DS-ALL should include improved supportive care throughout therapy and reduction of therapy in newly identified good-prognosis subgroups.

High modal number and triple trisomies are highly correlated favorable factors in childhood B-cell precursor high hyperdiploid acute lymphoblastic leukemia treated according to the NOPHO ALL 1992/2000 protocols

Between 1992 and 2008, 713 high hyperdiploid acute lymphoblastic leukemias in children aged 1-15 years were diagnosed and treated according to the Nordic Society for Pediatric Hematology and Oncology acute lymphoblastic leukemia 1992/2000 protocols. Twenty (2.8%) harbored t(1;19), t(9;22), der(11q23), or t(12;21). The median age of patients with "classic" high hyperdiploidy was lower than that of patients with translocation-positive high hyperdiploidy (P<0.001). Cases with triple trisomies (+4, +10, +17), comprising 50%, had higher modal numbers than the triple trisomy-negative cases (P<0.0001). The probabilities of event-free survival and overall survival were lower for those with white blood cell counts ≥ 50 × 10(9)/L (P=0.017/P=0.009), ≥ 5% bone marrow blasts at day 29 (P=0.001/0.002), and for high-risk patients (P<0.001/P=0.003), whereas event-free, but not overall, survival, was higher for cases with gains of chromosomes 4 (P<0.0001), 6 (P<0.003), 17 (P=0.010), 18 (P=0.049), and 22 (P=0.040), triple trisomies (P=0.002), and modal numbers >53/55 (P=0.020/0.024). In multivariate analyses, modal number and triple trisomies were significantly associated with superior event-free survival in separate analyses with age and white blood cell counts. When including both modal numbers and triple trisomies, only low white blood cell counts were significantly associated with superior event-free survival (P=0.009). We conclude that high modal chromosome numbers and triple trisomies are highly correlated prognostic factors and that these two parameters identify the same subgroup of patients characterized by a particularly favorable outcome.

Hospital admissions in children with down syndrome: experience of a population-based cohort followed from birth

Objective

Children with Down syndrome, the most common genetic cause of intellectual disability, are prone to multiple and varied health-related problems. This study describes patterns of hospitalisations for children and young people with Down syndrome in Western Australia.

Methods

Birth records were linked to the Western Australian population-based Intellectual Disability database to identify all children born with Down syndrome in Western Australia between 1 January, 1983 and 31 December, 1999. These records were linked to the Hospital Morbidity Data System to provide information on all hospitalisations up to 31 December, 2004. Hospitalisation data, coded using ICD-9CM or ICD-10 (v0.5) were grouped into clinically relevant categories using the primary diagnosis. Rates of hospital admission for all and specific diagnoses were expressed in 1000-person-years at-risk and median age at first admission and length of stay were calculated.

Results

Of the 405 children, 395 had one or more hospital admissions, totalling 3786 admissions for all children and an estimated 39.5 person-years in hospital. On average, children were admitted 9.7 times, with an estimated rate of 757.2 admissions per 1000pyr (95% CI: 680, 843). A quarter of all admissions occurred in the first year of life. The average hospital length of stay was 3.8 days (95% CI: 3.7, 4.1). Upper respiratory tract conditions affected the most children (58.5%) and accounted for 12.1% of all admissions. Other disorders which affected a high percentage of children were ear/hearing conditions (50.6%), disorders of the oral cavity (38.0%) and lower respiratory tract conditions (37.5%). Overall, children with Down syndrome were hospitalised at a rate five times (95% CI = 4.3–6.2) that of the general population.

Conclusion

Children with Down syndrome are at increased risk of morbidity for varied causes underlining the importance of comprehensive and targeted primary care for this group.

Physicians compliance during maintenance therapy in children with Down syndrome and acute lymphoblastic leukemia

Children with Down syndrome (DS) and acute lymphoblastic leukemia (ALL) have an inferior prognosis compared with non-DS ALL patients. We reviewed methotrexate (MTX)/mercaptopurine (6MP) maintenance therapy data for children with DS treated according to the Nordic Society of Pediatric Hematology and Oncology (NOPHO) ALL92 or the NOPHO ALL2000 protocols between 1992 and 2007. The 5-year event-free survival probability (pEFS(5 yr)) for the 66 DS patients was inferior to the 2602 non-DS patients (0.50 ± 0.07 vs 0.77 ± 0.01 (P<0.001)). The 48 DS patients in first remission at the beginning of maintenance therapy had pEFS(10 yr) below that of the 522 non-DS control patients (pEFS(10 yr): 0.58 (95% confidence interval (CI) 0.43-0.77) vs 0.83 (95% CI 0.80-0.86), respectively (P<0.0001)). The DS patients received lower median doses of MTX (median: 11.8 vs 15.4 (P<0.0001)) and 6MP (median: 43.6 vs 59.4 (P<0.0001)). In Cox regression analysis, male gender, presence of DS and high median maintenance therapy white blood cell levels (mWBC) were associated with increased risk for relapse. DS-ALL patients with mWBC above or below 3.5 × 10(9)/l (protocol target) had pEFS(10 yr) of 0.31 and 0.72 (P=0.02), and the mWBC hazard ratio for DS-ALL patients was 2.0 (P<0.0005). We conclude that insufficient treatment intensity during maintenance therapy of DS-ALL patients may contribute to their poor prognosis.

Outcome in children with Down's syndrome and acute lymphoblastic leukemia: role of IKZF1 deletions and CRLF2 aberrations

Children with Down's syndrome (DS) have an increased risk of developing acute lymphoblastic leukemia (ALL) and have a low frequency of established genetic aberrations. We aimed to determine which genetic abnormalities are involved in DS ALL. We studied the frequency and prognostic value of deletions in B-cell development genes and aberrations of janus kinase 2 (JAK2) and cytokine receptor-like factor 2 (CRLF2) using array-comparative genomic hybridization, and multiplex ligation-dependent probe amplification in a population-based cohort of 34 Dutch Childhood Oncology Group DS ALL samples. A population-based cohort of 88 DS samples from the UK trials was used to validate survival estimates for IKZF1 and CRLF2 abnormalities. In total, 50% of DS ALL patients had ≥1 deletion in the B-cell development genes: PAX5 (12%), VPREB1 (18%) and IKZF1 (35%). JAK2 was mutated in 15% of patients, genomic CRLF2 rearrangements in 62%. Outcome was significantly worse in patients with IKZF1 deletions (6-year event-free survival (EFS) 45 ± 16% vs 95 ± 4%; P=0.002), which was confirmed in the validation cohort (6-year EFS 21 ± 12% vs 58 ± 11%; P=0.002). This IKZF1 deletion was a strong independent predictor for outcome (hazard ratio EFS 3.05; P=0.001). Neither CRLF2 nor JAK2 were predictors for worse prognosis. If confirmed in prospective series, IKZF1 deletions may be used for risk-group stratification in DS ALL.

Myeloid leukemia in Down syndrome

Although adults with Down syndrome (DS) show a decreased incidence of cancer compared to individuals without DS, children with DS are at an increased risk of leukemia. Nearly half of these childhood leukemias are classified as acute megakaryoblastic leukemia (AMKL), a relatively rare subtype of acute myeloid leukemia (AML). Here, we summarize the clinical features of myeloid leukemia in DS, review recent research on the mechanisms of leukemogenesis, including the roles of GATA1 mutations and trisomy 21, and discuss treatment strategies. Given that trisomy 21 is a relatively common event in hematologic malignancies, greater knowledge of how the genes on chromosome 21 contribute to DS-AMKL will increase our understanding of a broader class of patients with leukemia.

High frequency of BTG1 deletions in acute lymphoblastic leukemia in children with down syndrome

Previous cytogenetic studies of myeloid and acute lymphoblastic leukemias in children with Down syndrome (ML-DS and DS-ALL) have revealed significant differences in abnormality patterns between such cases and acute leukemias in general. Also, certain molecular genetic aberrations characterize DS-related leukemias, such as GATA1 mutations in ML-DS and deregulation of the CRLF2 gene in DS-ALL. Whether microdeletions/microduplications also vary between DS and non-DS cases is presently unclear. To address this issue, we performed single nucleotide polymorphism array analyses of eight pediatric ML-DS and 17 B-cell precursor DS-ALL. In the ML-DS cases, a total of 29 imbalances (20 gains and nine losses) and two partial uniparental isodisomies (pUPDs) were detected. None of the 11 small (defined as <10 Mb) imbalances were recurrent, nor were the pUPDs, whereas of the 18 large aberrations, three were recurrent-dup(1q), +8 and +21. In contrast, several frequent changes were identified in the DS-ALL cases, which harbored 82 imbalances (30 gains and 52 losses) and four pUPDs. Of the 40 large changes, 28 were gains and 12 losses, with +X, dup(Xq), dup(1q), del(7p), dup(8q), del(9p), dup(9p), del(12p), dup(17q), and +21 being recurrent. Of the 40 microdeletions identified, several targeted specific genes, with the following being repeatedly deleted: BTG1 and CDKN2A/B (29% of cases), ETV6, IKZF1, PAX5 and SERP2 (18%), and BTLA, INPP4B, P2RY8, and RB1 (12%). Loss of the SERP2 and INPP4B genes, encoding the stress-associated endoplasmic reticulum protein family member 2 and the inositol polyphosphate 4-phosphatase-II, respectively, has previously never been implicated in leukemia. Although deletions of the other genes have been associated with ALL, the high frequency of BTG1 loss is a novel finding. Such deletions may characterize a clinical subgroup of DS-ALL, comprising mainly boys with a high median age. In conclusion, ML-DS and DS-ALL are genetically distinct, with mainly gains in ML-DS and deletions in DS-ALL. Furthermore, DS-ALL is characterized by several recurrent gene deletions, with BTG1 loss being particularly frequent.