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

Antileukemic effect of azacitidine, a DNA methyltransferase inhibitor, on cell lines of myeloid leukemia associated with Down syndrome

Myeloid leukemia associated with Down syndrome (ML-DS) responds well to chemotherapy and has a favorable prognosis, but the clinical outcome of patients with refractory or relapsed ML-DS is dismal. We recently reported a case of relapsed ML-DS with an effective response to a DNA methyltransferase inhibitor, azacitidine (AZA). However, the efficacy of AZA for refractory or relapsed ML-DS remains uncertain. Here, we investigated the effects and mechanism of action of AZA on three ML-DS cell lines derived from relapsed cases. AZA inhibited the proliferation of all examined ML-DS cell lines to the same extent as that of AZA-sensitive acute myeloid leukemia non-Down syndrome cell lines. Transient low-dose AZA treatment exerted durable antileukemic effects on ML-DS cells. The inhibitory effect included cell cycle arrest, apoptosis, and reduction of aldehyde dehydrogenase activity. Comprehensive differential gene expression analysis showed that AZA induced megakaryocytic differentiation in all ML-DS cell lines examined. Furthermore, AZA induced activation of type I interferon-stimulated genes, primarily involved in antiproliferation signaling, without stimulation of the interferon receptor-mediated autocrine system. Activation of the type I interferon pathway by stimulation with interferon-α exerted antiproliferative effects on ML-DS cells, suggesting that AZA exerts its antileukemic effects on ML-DS cells at least partially through the type I interferon pathway. Moreover, the effect of AZA on normal hematopoiesis did not differ significantly between individuals with non-Down syndrome and Down syndrome. In summary, this study suggests that AZA is a potentially effective treatment option for ML-DS disease control, including relapsed cases, and has reduced side effects.

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.

Too many white cells-TAM, JMML, or something else?

Leukocytosis is a common finding in pediatric patients, and the differential diagnosis can be broad, including benign reactive leukocytosis and malignant myeloproliferative disorders. Transient abnormal myelopoiesis is a myeloproliferative disorder that occurs in young infants with constitutional trisomy 21 and somatic GATA1 mutations. Most patients are observed, but outcomes span the spectrum from spontaneous resolution to life-threatening complications. Juvenile myelomonocytic leukemia is a highly aggressive myeloproliferative disorder associated with altered RAS-pathway signaling that occurs in infants and young children. Treatment typically involves hematopoietic stem cell transplantation, but certain patients can be observed. Early recognition of these and other myeloproliferative disorders is important and requires a clinician to be aware of these diagnoses and have a clear understanding of their presentations. This paper discusses the presentation and evaluation of leukocytosis when myeloproliferative disorders are part of the differential and reviews different concepts regarding treatment strategies.

Survival outcomes of children with relapsed or refractory myeloid leukemia associated with Down syndrome

Children with Down syndrome (DS) are at a significantly higher risk of developing acute myeloid leukemia, also termed myeloid leukemia associated with DS (ML-DS). In contrast to the highly favorable prognosis of primary ML-DS, the limited data that are available for children who relapse or who have refractory ML-DS (r/r ML-DS) suggest a dismal prognosis. There are few clinical trials and no standardized treatment approach for this population. We conducted a retrospective analysis of international study groups and pediatric oncology centers and identified 62 patients who received treatment with curative intent for r/r ML-DS between year 2000 to 2021. Median time from diagnosis to relapse was 6.8 (range, 1.1-45.5) months. Three-year event-free survival (EFS) and overall survival (OS) were 20.9 ± 5.3% and 22.1 ± 5.4%, respectively. Survival was associated with receipt of hematopoietic stem cell transplantation (HSCT) (hazard ratio [HR], 0.28), duration of first complete remission (CR1) (HR, 0.31 for > 12 months) and attainment of remission after relapse (HR, 4.03). Patients who achieved complete remission (CR) before HSCT, had an improved OS and EFS of 56.0 ± 11.8% and 50.5 ± 11.9%, respectively compared to those who underwent HSCT without CR (3-year OS and EFS of 10.0 ± 9.5%). Treatment failure after HSCT was predominantly because of disease recurrence (52%) followed by treatment-related mortality (10%). The prognosis of r/r ML-DS remains dismal even in the current treatment period and serve as a reference point for current prognostication and future interventional studies. Clinical trials aimed at improving the survival of patients with r/r ML-DS are needed.

Management of Down Syndrome-Associated Leukemias: A Review

Importance

Down syndrome (DS), caused by an extra copy of material from chromosome 21, is one of the most common genetic conditions. The increased risk of acute leukemia in DS (DS-AL) has been recognized for decades, consisting of an approximately 150-fold higher risk of acute myeloid leukemia (AML) before age 4 years, and a 10- to 20-fold higher risk of acute lymphoblastic leukemia (ALL), compared with children without DS.

Observations

A recent National Institutes of Health-sponsored conference, ImpacT21, reviewed research and clinical trials in children, adolescents, and young adults (AYAs) with DS-AL and are presented herein, including presentation and treatment, clinical trial design, and ethical considerations for this unique population. Between 10% to 30% of infants with DS are diagnosed with transient abnormal myelopoiesis (TAM), which spontaneously regresses. After a latency period of up to 4 years, 20% to 30% develop myeloid leukemia associated with DS (ML-DS). Recent studies have characterized somatic mutations associated with progression from TAM to ML-DS, but predicting which patients will progress to ML-DS remains elusive. Clinical trials for DS-AL have aimed to reduce treatment-related mortality (TRM) and improve survival. Children with ML-DS have better outcomes compared with non-DS AML, but outcomes remain dismal in relapse. In contrast, patients with DS-ALL have inferior outcomes compared with those without DS, due to both higher TRM and relapse. Management of relapsed leukemia poses unique challenges owing to disease biology and increased vulnerability to toxic effects. Late effects in survivors of DS-AL are an important area in need of further study because they may demonstrate unique patterns in the setting of chronic medical conditions associated with DS.

Conclusions and Relevance

Optimal management of DS-AL requires specific molecular testing, meticulous supportive care, and tailored therapy to reduce TRM while optimizing survival. There is no standard approach to treatment of relapsed disease. Future work should include identification of biomarkers predictive of toxic effects; enhanced clinical and scientific collaborations; promotion of access to novel agents through innovative clinical trial design; and dedicated studies of late effects of treatment.

Myeloid Leukemia of Down Syndrome

Myeloid leukemia of Down syndrome (ML-DS) is characterized by a distinct natural history and is classified by the World Health Organization (WHO) as an independent entity, occurring with unique clinical and molecular features. The presence of a long preleukemic, myelodysplastic phase, called transient abnormal myelopoiesis (TAM), precedes the initiation of ML-DS and is defined by unusual chromosomal findings. Individuals with constitutional trisomy 21 have a profound dosage imbalance in the hematopoiesis-governing genes located on chromosome 21 and thus are subject to impaired fetal as well as to neonatal erythro-megakaryopoiesis. Almost all neonates with DS develop quantitative and morphological hematological abnormalities, yet still only 5-10% of them present with one of the preleukemic or leukemic conditions of DS. The acquired mutations in the key hematopoietic transcription factor gene GATA1, found solely in cells trisomic for chromosome 21, are considered to be the essential step for the selective growth advantage of leukemic cells. While the majority of cases of TAM remain clinically 'silent' or undergo spontaneous remission, the remaining 20% to 30% of them progress into ML-DS until the age of 4 years. The hypersensitivity of ML-DS blasts to chemotherapeutic agents, including but not limited to cytarabine, and drugs' increased infectious and cardiac toxicity have necessitated the development of risk-adapted treatment protocols for children with ML-DS. Recent advances in cytogenetics and specific molecular mechanisms involved in the evolution of TAM and ML-DS are reviewed here, as well as their integration in the improvement of risk stratification and targeted management of ML-DS.

Comprehensive molecular understanding of pediatric acute myeloid leukemia

Pediatric acute myeloid leukemia (AML) is a heterogeneous disease with various genetic abnormalities. Recent advances in genetic analysis have enabled the identification of causative genes in > 90% of pediatric AML cases. Fusion genes such as RUNX1::RUNX1T1, CBFB::MYH11, and KMT2A::MLLT3 are frequently detected in > 70% of pediatric AML cases, whereas FLT3-internal tandem duplication, CEBPA-bZip, and NPM1 mutations are detected in approximately 5-15% of cases, respectively. Conversely, mutations in DNMT3A, TET2, and IDH, which are common in adults, are extremely rare in pediatric AML. The genetic characteristics of pediatric AML are slightly different from those of adult AML. For accurate risk stratification and treatment intensity, genome analysis should be performed in a simple, fast, and inexpensive manner and the results should be returned to patients in real time. As with acute lymphoblastic leukemia, the presence or absence of minimal residual disease is an important factor in determining the success of treatment against AML, and it is important to predict prognosis and formulate treatment strategies considering the genetic abnormalities. For the development and clinical application of new molecularly targeted therapies based on identified genetic abnormalities, it is necessary to explore when and in which combinations drugs will be most effective.

Clonal Myeloproliferative Disorders in Patients with Down Syndrome-Treatment and Outcome Results from an Institution in Argentina

Children with Down syndrome (DS) are at an increased risk of developing clonal myeloproliferative disorders. The balance between treatment intensity and treatment-related toxicity has not yet been defined. We analyzed this population to identify risk factors and optimal treatment. This single-center retrospective study included 78 DS patients <16 years-old with Transient Abnormal Myelopoiesis (TAM, n = 25), Acute Myeloblastic Leukemia (DS-AML, n = 41) of which 35 had classical Myeloid Leukemia associated with DS (ML-DS) with megakaryoblastic immunophenotype (AMKL) and 6 sporadic DS-AML (non-AMKL). Patients with DS-AML were treated according to four BFM-based protocols. Classical ML-DS vs. non-DS-AMKL were compared and the outcome of ML-DS was analyzed according to treatment intensity. Only four patients with TAM required cytoreduction with a 5-year Event-Free Survival probability (EFSp) of 74.4 (±9.1)%. DS-AML treatment-related deaths were due to infections, with a 5-year EFSp of 60.6 (±8.2)%. Megakaryoblastic immunophenotype was the strongest good-prognostic factor in univariate and multivariate analysis (p = 0.000). When compared ML-DS with non-DS-AMKL, a better outcome was associated with a lower relapse rate (p = 0.0002). Analysis of administered treatment was done on 32/33 ML-DS patients who achieved CR according to receiving or not high-dose ARA-C block (HDARA-C), and no difference in 5-year EFSp was observed (p = 0.172). TAM rarely required treatment and when severe manifestations occurred, early intervention was effective. DS-AML good outcome was associated with AMKL with a low relapse-rate. Even if treatment-related mortality is still high, our data do not support the omission of HDARA-C in ML-DS since we observed a trend to detect a higher relapse rate in the arm without HDARA-C.

The Paradox of Myeloid Leukemia Associated with Down Syndrome

Children with Down syndrome constitute a distinct genetic population who has a greater risk of developing acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) compared to their non-Down syndrome counterparts. The risk for developing solid tumors is also distinct from the non-Down syndrome population. In the case of myeloid leukemias, the process of leukemogenesis in Trisomy 21 begins in early fetal life where genetic drivers including GATA1 mutations lead to the development of the preleukemic condition, transient abnormal myelopoiesis (TAM). Various other mutations in genes encoding cohesin, epigenetic regulators and RAS pathway can result in subsequent progression to Myeloid Leukemia associated with Down Syndrome (ML-DS). The striking paradoxical feature in the Down syndrome population is that even though there is a higher predisposition to developing AML, they are also very sensitive to chemotherapy agents, particularly cytarabine, thus accounting for the very high cure rates for ML-DS compared to AML in children without Down syndrome. Current clinical trials for ML-DS attempt to balance effective curative therapies while trying to reduce treatment-associated toxicities including infections by de-intensifying chemotherapy doses, if possible. The small proportion of patients with relapsed ML-DS have an extremely poor prognosis and require the development of new therapies.

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.

Post-induction MRD by FCM and GATA1-PCR are significant prognostic factors for myeloid leukemia of Down syndrome

Myeloid leukemia of Down syndrome (ML-DS) is associated with good response to chemotherapy, resulting in favorable outcomes. However, no universal prognostic factors have been identified to date. To clarify a subgroup with high risk of relapse, the role of minimal residual disease (MRD) was explored in the AML-D11 trial by the Japanese Pediatric Leukemia/Lymphoma Study Group. MRD was prospectively evaluated at after induction therapy and at the end of all chemotherapy, using flow cytometry (FCM-MRD) and GATA1-targeted deep sequencing (GATA1-MRD). A total of 78 patients were eligible and 76 patients were stratified to the standard risk (SR) group by morphology. In SR patients, FCM-MRD and GATA1-MRD after induction were positive in 5/65 and 7/59 patients, respectively. Three-year event-free survival (EFS) and overall survival (OS) rates were 95.0% and 96.7% in the FCM-MRD-negative population, and 60.0% and 80.0% in the positive population. Three-year EFS and OS rates were both 98.1% in the GATA1-MRD-negative population, and 57.1% and 71.4% in the positive population. Adjusted hazard ratios for associations of FCM-MRD with EFS were 14.67 (p = 0.01). Detection of MRD by either FCM or GATA1 after initial induction therapy represents a significant prognostic factor for predicting ML-DS relapse.

Gain of chromosome 21 in hematological malignancies: lessons from studying leukemia in children with Down syndrome

Structural and numerical alterations of chromosome 21 are extremely common in hematological malignancies. While the functional impact of chimeric transcripts from fused chromosome 21 genes such as TEL-AML1, AML1-ETO, or FUS-ERG have been extensively studied, the role of gain of chromosome 21 remains largely unknown. Gain of chromosome 21 is a frequently occurring aberration in several types of acute leukemia and can be found in up to 35% of cases. Children with Down syndrome (DS), who harbor constitutive trisomy 21, highlight the link between gain of chromosome 21 and leukemogenesis, with an increased risk of developing acute leukemia compared with other children. Clinical outcomes for DS-associated leukemia have improved over the years through the development of uniform treatment protocols facilitated by international cooperative groups. The genetic landscape has also recently been characterized, providing an insight into the molecular pathogenesis underlying DS-associated leukemia. These studies emphasize the key role of trisomy 21 in priming a developmental stage and cellular context susceptible to transformation, and have unveiled its cooperative function with additional genetic events that occur during leukemia progression. Here, using DS-leukemia as a paradigm, we aim to integrate our current understanding of the role of trisomy 21, of critical dosage-sensitive chromosome 21 genes, and of associated mechanisms underlying the development of hematological malignancies. This review will pave the way for future investigations on the broad impact of gain of chromosome 21 in hematological cancer, with a view to discovering new vulnerabilities and develop novel targeted therapies to improve long term outcomes for DS and non-DS patients.

Successful Treatment With ATRA and Arsenic Trioxide for a Child With Down Syndrome and Acute Promyelocytic Leukemia

Acute promyelocytic leukemia (APL) is rare in patients with Down syndrome (DS). Cytotoxic chemotherapy combined with all-trans retinoic acid (ATRA) has been a standard treatment for APL, but is potentially intolerable for DS patients because of their vulnerability to cytotoxic agents. We report here a case of a 10-year-old girl with DS and APL successfully treated with a combination of ATRA and arsenic trioxide, a therapy emerging as a new standard for APL. She achieved molecular remission and completed the therapy without significant toxicities. ATRA/arsenic trioxide combination therapy would be a preferable option for DS patients with APL.

Retrospective Analysis of the Treatment Outcome in Myeloid Leukemia of Down Syndrome in Polish Pediatric Leukemia and Lymphoma Study Group From 2005 to 2019

Background: Children with Down syndrome (DS) have increased risk of myeloid leukemia (ML), but specific treatment protocols ensure excellent outcome. This study was a retrospective analysis of the treatment results and genetic characteristics of ML of DS (ML-DS) in Poland from 2005 to 2019. Methods: All 54 patients with ML-DS registered in the Polish Pediatric Leukemia and Lymphoma Study Group in analyzed period were enrolled to the study. There were 34 children treated with Acute Myeloid Leukemia-Berlin-Frankfurt-Munster 2004 Interim Protocol (group I) and 20 patients treated with ML-DS 2006 Protocol (group II). In the first protocol, there was reduction of the antracyclines doses and intrathecal treatment for ML-DS compared to non-DS patients. In the second protocol, further reduction of the treatment was introduced (omission of etoposide in the last cycle, no maintenance therapy). Results: Probabilities of 5-year overall survival (OS), event-free survival (EFS), and relapse-free survival in the whole analyzed group were 0.85 ± 0.05, 0.83 ± 0.05, and 0.97 ± 0.03, respectively. No significant differences were found between two protocols in the terms of OS and EFS (0.79 ± 0.07 vs. 0.95 ± 0.05, p = 0.14, and 0.76 ± 0.07 vs. 0.95 ± 0.05, p = 0.12, respectively). All deaths were caused by the treatment-related toxicities. Reduction of the treatment-related mortality was noticed (20% in group I and 5% in group II). The only one relapse in the whole cohort occurred in the patient from group I, older than 4 years, without GATA1 gene mutation. He was treated successfully with IdaFLA cycle followed by hematopoietic stem cell transplantation from matched sibling donor. No significant prognostic factor was found in the study group probably due to low number of patients in the subgroups. Conclusions: The study confirms that the reduced intensity protocols are very effective in ML-DS patients. The only cause of deaths was toxicities; however, systematic decrease of the treatment-related mortality was noticed.

GATA1 and cooperating mutations in myeloid leukaemia of Down syndrome

Myeloid leukaemia of Down syndrome (ML-DS) is an acute megakaryoblastic/erythroid leukaemia uniquely found in children with Down syndrome (constitutive trisomy 21). It has a unique clinical course, being preceded by a pre-leukaemic condition known as transient abnormal myelopoiesis (TAM), and provides an excellent model to study multistep leukaemogenesis. Both TAM and ML-DS blasts carry acquired N-terminal truncating mutations in the erythro-megakaryocytic transcription factor GATA1. These result in exclusive production of a shorter isoform (GATA1s). The majority of TAM cases resolve spontaneously without the need for treatment; however, around 10% acquire additional cooperating mutations and transform to leukaemia, with differentiation block and clinically significant cytopenias. Transformation is driven by the acquisition of additional mutation(s), which cooperate with GATA1s to perturb normal haematopoiesis.

Characteristics and outcomes of children with acute myeloid leukemia and Down syndrome who are ineligible for clinical trials due to severe comorbidities

BACKGROUND

High survival rates of 80-90% have been reported in recent clinical trials of reduced-intensity chemotherapies for children with acute myeloid leukemia and Down syndrome (AML-DS). However, a certain number of children with AML-DS have complicating comorbidities, including congenital heart disease (CHD), and are therefore ineligible for enrolment in clinical trials.

METHODS

We retrospectively analyzed the clinical characteristics and outcomes of children with AML-DS who were excluded from Japanese clinical trials conducted between 2000 and 2015.

RESULTS

Twelve children (six males and six females) were identified and were ineligible for CHD (n = 8) and other comorbidities, including hyperleukocytosis complicated with coagulopathy, severe hemophagocytosis, pulmonary fibrosis, and hypoxic-ischemic encephalopathy (n = 1 each). The median age at the diagnosis was 14 months (range, 5 months to 11.5 years). Among all cases, 11 patients were treated with curative intent. Four patients were considered intolerant to intensive chemotherapy and received only low-dose cytarabine-based chemotherapy: three failed to achieve remission and died of disease, while one successfully achieved remission but eventually died of infection. Seven cases underwent regular-intensive chemotherapy for AML-DS: six were alive and in remission; one had relapsed disease. One patient who received the best supportive care died of disease. Finally, six patients remained in continuous complete remission, while six died. The 5-year overall survival rate was 51%.

CONCLUSIONS

The prognosis of AML-DS patients who received insufficient treatment due to severe complication was poor. The optimal dose intensity of curative chemotherapy for such cases should be explored.

Highly sensitive detection of GATA1 mutations in patients with myeloid leukemia associated with Down syndrome by combining Sanger and targeted next generation sequencing

Myeloid leukemia associated with Down syndrome (ML-DS) is characterized by a predominance of acute megakaryoblastic leukemia, the presence of GATA1 mutations and a favorable outcome. Because DS children can also develop conventional acute myeloid leukemia with unfavorable outcome, detection of GATA1 mutations is important for diagnosis of ML-DS. However, myelofibrosis and the significant frequency of dry taps have hampered practical screening of GATA1 mutations using bone marrow (BM) samples. In response to those problems, 82 patients were enrolled in the Japanese Pediatric Leukemia/Lymphoma Study Group AML-D11 study. GATA1 mutations were analyzed by Sanger sequencing (SS) using genomic DNA (gDNA) from BM and cDNA from peripheral blood (PB) followed by targeted next-generation sequencing (NGS) using pooled diagnostic samples. BM and PB samples were obtained from 71 (87%) and 82 (100%) patients, respectively. GATA1 mutations were detected in 46 (56%) and 58 (71%) patients by SS using BM gDNA and PB cDNA, respectively. Collectively, GATA1 mutations were identified in 73/82 (89%) patients by SS. Targeted NGS detected GATA1 mutations in 74/82 (90%) patients. Finally, combining the results of SS with those of targeted NGS, GATA1 mutations were identified in 80/82 (98%) patients. These results indicate that SS using BM gDNA and PB cDNA is a rapid and useful method for screening for GATA1 mutations in ML-DS patients. Thus, a combination of SS and targeted NGS is a sensitive and useful method to evaluate the actual incidence and clinical significance of GATA1 mutations in ML-DS patients.

Pathologic Features of Down Syndrome Myelodysplastic Syndrome and Acute Myeloid Leukemia: A Report From the Children's Oncology Group Protocol AAML0431

CONTEXT.—

Detailed diagnostic features of acute myeloid leukemia in Down syndrome are lacking, leading to potential misdiagnoses as standard acute myeloid leukemia occurring in patients with Down syndrome.

OBJECTIVE.—

To evaluate diagnostic features of acute myeloid leukemia and myelodysplastic syndrome in patients with Down syndrome.

DESIGN.—

Diagnostic bone marrow samples from 163 patients enrolled in the Children's Oncology Group study AAML0431 were evaluated by using central morphologic review and institutional immunophenotyping. Results were compared to overall survival, event-free survival, GATA1 mutation status, cytogenetics, and minimal residual disease results.

RESULTS.—

Sixty myelodysplastic syndrome and 103 acute myeloid leukemia samples were reviewed. Both had distinctive features compared to those of patients without Down syndrome. They showed megakaryocytic and erythroid but little myeloid dysplasia, and marked megakaryocytic hyperplasia with unusual megakaryocyte morphology. In acute myeloid leukemia cases, megakaryoblastic differentiation of blasts was most common (54 of 103, 52%); other cases showed erythroblastic (11 of 103, 11%), mixed erythroid/megakaryoblastic (20 of 103, 19%), or no differentiation (10 of 103, 10%). Myelodysplastic syndrome and acute myeloid leukemia cases had similar event-free survival and overall survival. Leukemic subgroups showed interesting, but not statistically significant, trends for survival and minimal residual disease. Cases with institutional diagnoses of French American British M1-5 morphology showed typical features of Down syndrome disease, with survival approaching that of other cases.

CONCLUSIONS.—

Myelodysplastic syndrome and acute myeloid leukemia in Down syndrome display features that allow discrimination from standard cases of disease. These distinctions are important for treatment decisions, and for understanding disease pathogenesis. We propose specific diagnostic criteria for Down syndrome-related subtypes of acute myeloid leukemia and myelodysplastic syndrome.

Epigenetic Therapy in a Patient With Down Syndrome and Refractory Acute Myeloid Leukemia

Acute myeloid leukemia (AML) associated with Down syndrome (DS-AML) is a unique entity of AML with superior treatment response and overall survival compared with children with non-DS-AML. Despite good outcomes in DS-AML, those who relapse or have refractory disease have poor survival. Successful treatment of these patients is challenged by increased incidence of treatment-related toxicities often encountered with high-dose chemotherapy. Here we report the experience of epigenetic modifying agents (decitabine and vorinostat) followed by fludarabine, cytarabine, and granulocyte colony stimulating growth factor for a child with refractory DS-AML. This combination was well tolerated and resulted in a brief clinical response.

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.

Therapy reduction in patients with Down syndrome and myeloid leukemia: the international ML-DS 2006 trial

Reducing therapy intensity in the ML-DS 2006 trial did not impair the excellent prognosis in ML-DS compared with the historical control. Early treatment response and gain of chromosome 8 are independent prognostic factors.

Down syndrome and AML: where do we go from here?

It is well documented that young children with Down syndrome (DS) have both a 500-fold increased incidence of acute myeloid leukemia (ML-DS) and a decreased tolerance of intensive chemotherapy. In this issue of Blood, Uffmann et al present the results of a large, multicentered, international, nonrandomized trial reducing the etoposide exposure while preserving the excellent outcomes reported in previous trials.1 This trial builds on international experience demonstrating that most young children with ML-DS may be cured with less intensive therapy, and confirms that there remains a significant subset of patients for whom we have limited therapeutic options.

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.

Acute and late toxicities of pirarubicin in the treatment of childhood acute lymphoblastic leukemia: results from a clinical trial by the Japan Association of Childhood Leukemia Study

BACKGROUND

Anthracyclines are used to treat childhood acute lymphoblastic leukemia (ALL). Even when administered at low doses, these agents are reported to cause progressive cardiac dysfunction. We conducted a clinical trial comparing the toxicities of two anthracyclines, pirarubicin (THP) and daunorubicin (DNR), in the treatment of childhood ALL. The results from our study that relate to acute and late toxicities are reported here.

METHODS

276 children with B-ALL were enrolled in the trial from April 1997 to March 2002 and were randomly assigned to receive a regimen including either THP (25 mg/m² × 11) or DNR (30 mg/m² × 11). Acute toxicity was prospectively assessed based on the National Cancer Institute Common Toxicity Criteria. Acute hematological toxicity was also examined via some parameters. Patients with event-free survival of >5 years were retrospectively surveyed for cardiac function at 5 and 10 years and at the most recent assessment more than 10 years from the onset of ALL.

RESULTS

Acute hematological toxicity in the early phase was more significant in the THP arm. Based on ultrasound cardiography, cardiac function was impaired in both groups during the follow-up period, but there was no significant difference between the groups except for a greater decline in fractional shortening on ultrasound cardiography in the DNR arm.

CONCLUSIONS

While acute hematological toxicity was more significant in the THP arm, THP also appeared to be less cardiotoxic. However, the evaluation of late cardiotoxicity was limited because only a few subjects were followed beyond 10 years after ALL onset. Considering that the THP regimen produced an EFS rate comparable with that of the DNR regimen, the efficacy and toxicity of THP at reduced doses should be studied in order to identify potentially safer regimens.

Transient Abnormal Myelopoiesis and AML in Down Syndrome: an Update

Children with constitutional trisomy 21 (Down syndrome (DS)) have a unique predisposition to develop myeloid leukaemia of Down syndrome (ML-DS). This disorder is preceded by a transient neonatal preleukaemic syndrome, transient abnormal myelopoiesis (TAM). TAM and ML-DS are caused by co-operation between trisomy 21, which itself perturbs fetal haematopoiesis and acquired mutations in the key haematopoietic transcription factor gene GATA1. These mutations are found in almost one third of DS neonates and are frequently clinically and haematologcially 'silent'. While the majority of cases of TAM undergo spontaneous remission, ∼10 % will progress to ML-DS by acquiring transforming mutations in additional oncogenes. Recent advances in the unique biological, cytogenetic and molecular characteristics of TAM and ML-DS are reviewed here.

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.