Pediatric acute myeloid leukemia with t(8;16)(p11;p13), a distinct clinical and biological entity: a collaborative study by the International-Berlin-Frankfurt-Munster AML-study group

[SFCE harmonization workshops: Neonatal acute myeloid leukemia]

Neonatal acute myeloid leukemias (AML) occurred within the first 28 days of life and constitute only a small proportion of all AL. They are distinguished from leukemias of older children by their clinical presentation, which frequently includes cutaneous localizations ("blueberry muffin rash syndrome") and a leukocytosis above 50 ×109/L. This proliferation may be transient, causing a transient leukemoid reaction in a background of constitutional trisomy 21 ("Transient Abnormal Myelopoieseis" or TAM) or Infantile Myeloproliferative Disease in the absence of constitutional trisomy 21 ("Infantile Myeloproliferative Disease" or IMD). In cases of true neonatal AML, the prognosis of patients is poor. Overall survival is around 35 % in the largest historical series. This poor prognosis is mainly due to the period of onset of this pathology making the use of chemotherapy more limited and involving many considerations, both ethical and therapeutic. The objective of this work is to review this rare pathology by addressing the clinical, biological, therapeutic and ethical particularities of patients with true neonatal AML or transient leukemoid reactions occurring in a constitutional trisomy 21 (true TAM) or somatic background (IMD).

Acute myeloid leukemia with rare recurring translocations-an overview of the entities included in the international consensus classification

Two different systems exist for subclassification of acute myeloid leukemia (AML); the World Health Organization (WHO) Classification and the International Consensus Classification (ICC) of myeloid malignancies. The two systems differ in their classification of AML defined by recurrent chromosomal abnormalities. One difference is that the ICC classification defines an AML subset that includes 12 different genetic abnormalities that occur in less than 4% of AML patients. These subtypes exhibit distinct clinical traits and are associated with treatment outcomes, but detailed description of these entities is not easily available and is not described in detail even in the ICC. We searched in the PubMed database to identify scientific publications describing AML patients with the recurrent chromosomal abnormalities/translocations included in this ICC defined patient subset. This patient subset includes AML with t(1;3)(p36.3;q21.3), t(3;5)(q25.3;q35.1), t(8;16)(p11.2;p13.3), t(1;22)(p13.3;q13.1), t(5;11)(q35.2;p15.4), t(11;12)(p15.4;p13.3) (involving NUP98), translocation involving NUP98 and other partner, t(7;12)(q36.3;p13.2), t(10;11)(p12.3;q14.2), t(16;21)(p11.2;q22.2), inv(16)(p13.3q24.3) and t(16;21)(q24.3;q22.1). In this updated review we describe the available information with regard to frequency, biological functions of the involved genes and the fusion proteins, morphology/immunophenotype, required diagnostic procedures, clinical characteristics (including age distribution) and prognostic impact for each of these 12 genetic abnormalities.

Cytogenetic abnormalities predict survival after allogeneic hematopoietic stem cell transplantation for pediatric acute myeloid leukemia: a PDWP/EBMT study

Poor-risk (PR) cytogenetic/molecular abnormalities generally direct pediatric patients with acute myeloid leukemia (AML) to allogeneic hematopoietic stem cell transplant (HSCT). We assessed the predictive value of cytogenetic risk classification at diagnosis with respect to post-HSCT outcomes in pediatric patients. Patients younger than 18 years at the time of their first allogeneic HSCT for AML in CR1 between 2005 and 2022 who were reported to the European Society for Blood and Marrow Transplantation registry were subgrouped into four categories. Of the 845 pediatric patients included in this study, 36% had an 11q23 abnormality, 24% had monosomy 7/del7q or monosomy 5/del5q, 24% had a complex or monosomal karyotype, and 16% had other PR cytogenetic abnormalities. In a multivariable model, 11q23 (hazard ratio [HR] = 0.66, P = 0.03) and other PR cytogenetic abnormalities (HR = 0.55, P = 0.02) were associated with significantly better overall survival when compared with monosomy 7/del7q or monosomy 5/del5q. Patients with other PR cytogenetic abnormalities had a lower risk of disease relapse after HSCT (HR = 0.49, P = 0.01) and, hence, better leukemia-free survival (HR = 0.55, P = 0.01). Therefore, we conclude that PR cytogenetic abnormalities at diagnosis predict overall survival after HSCT for AML in pediatric patients.

Rare Hematologic Malignancies and Pre-Leukemic Entities in Children and Adolescents Young Adults

There are a variety of rare hematologic malignancies and germline predispositions syndromes that occur in children and adolescent young adults (AYAs). These entities are important to recognize, as an accurate diagnosis is essential for risk assessment, prognostication, and treatment. This descriptive review summarizes rare hematologic malignancies, myelodysplastic neoplasms, and germline predispositions syndromes that occur in children and AYAs. We discuss the unique biology, characteristic genomic aberrations, rare presentations, diagnostic challenges, novel treatments, and outcomes associated with these rare entities.

Genetics of Acquired Cytokine Storm Syndromes : Secondary HLH Genetics

Secondary hemophagocytic lymphohistiocytosis (sHLH) has historically been defined as a cytokine storm syndrome (CSS) occurring in the setting of triggers leading to strong and dysregulated immunological activation, without known genetic predilection. However, recent studies have suggested that existing underlying genetic factors may synergize with particular diseases and/or environmental triggers (including infection, autoimmune/autoinflammatory disorder, certain biologic therapies, or malignant transformation), leading to sHLH. With the recent advances in genetic testing technology, more patients are examined for genetic variations in primary HLH (pHLH)-associated genes, including through whole exome and whole genome sequencing. This expanding genetic and genomic evidence has revealed HLH as a more complex phenomenon, resulting from specific immune challenges in patients with a susceptible genetic background. Rather than a simple, binary definition of pHLH and sHLH, HLH represents a spectrum of diseases, from a severe complication of common infections (EBV, influenza) to early onset familial diseases that can only be cured by transplantation.

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.

Cytogenetics in the management of acute myeloid leukemia and histiocytic/dendritic cell neoplasms: Guidelines from the Groupe Francophone de Cytogénétique Hématologique (GFCH)

Genetic data are becoming increasingly essential in the management of hematological neoplasms as shown by two classifications published in 2022: the 5th edition of the World Health Organization Classification of Hematolymphoid Tumours and the International Consensus Classification of Myeloid Neoplasms and Acute Leukemias. Genetic data are particularly important for acute myeloid leukemias (AMLs) because their boundaries with myelodysplastic neoplasms seem to be gradually blurring. The first objective of this review is to present the latest updates on the most common cytogenetic abnormalities in AMLs while highlighting the pitfalls and difficulties that can be encountered in the event of cryptic or difficult-to-detect karyotype abnormalities. The second objective is to enhance the role of cytogenetics among all the new technologies available in 2023 for the diagnosis and management of AML.

Risk-Stratified Therapy for Pediatric Acute Myeloid Leukemia

Acute Myeloid Leukemia (AML) is the second most common type of leukemia in children. Recent advances in high-resolution genomic profiling techniques have uncovered the mutational landscape of pediatric AML as distinct from adult AML. Overall survival rates of children with AML have dramatically improved in the past 40 years, currently reaching 70% to 80% in developed countries. This was accomplished by the intensification of conventional chemotherapy, improvement in risk stratification using leukemia-specific cytogenetics/molecular genetics and measurable residual disease, appropriate use of allogeneic hematopoietic stem cell transplantation, and improvement in supportive care. However, the principle therapeutic approach for pediatric AML has not changed substantially for decades and improvement in event-free survival is rather modest. Further refinements in risk stratification and the introduction of emerging novel therapies to contemporary therapy, through international collaboration, would be key solutions for further improvements in outcomes.

Analysis of rare driving events in pediatric acute myeloid leukemia

Elucidating genetic aberrations in pediatric acute myeloid leukemia (AML) provides insight in biology and may impact on risk-group stratification and clinical outcome. This study aimed to detect such aberrations in a selected series of samples without known (cyto)genetic aberration using molecular profiling. A cohort of 161 patients was selected from various study groups: DCOG, BFM, SJCRH, NOPHO and AEIOP. Samples were analyzed using RNA sequencing (n=152), whole exome (n=135) and/or whole genome sequencing (n=100). In 70 of 156 patients (45%), of whom RNA sequencing or whole genome sequencing was available, rearrangements were detected, 22 of which were novel; five involving ERG rearrangements and four NPM1 rearrangements. ERG rearrangements showed self-renewal capacity in vitro, and a distinct gene expression pattern. Gene set enrichment analysis of this cluster showed upregulation of gene sets derived from Ewing sarcoma, which was confirmed comparing gene expression profiles of AML and Ewing sarcoma. Furthermore, NPM1-rearranged cases showed cytoplasmic NPM1 localization and revealed HOXA/B gene overexpression, as described for NPM1 mutated cases. Single-gene mutations as identified in adult AML were rare. Patients had a median of 24 coding mutations (range, 7-159). Novel recurrent mutations were detected in UBTF (n=10), a regulator of RNA transcription. In 75% of patients an aberration with a prognostic impact could be detected. Therefore, we suggest these techniques need to become standard of care in diagnostics.

Hoxa11-mediated reduction of cell migration contributes to myeloid sarcoma formation induced by cooperation of MLL/AF10 with activating KRAS mutation in a mouse transplantation model

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Acute myeloid leukemia (AML) patients with MLL translocations (MLL-t) are frequently found to harbor N-/K-RAS activating mutations.

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Mouse models revealed that cooperating mutations accelerated leukemia development and myeloid sarcoma formation.

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The molecular mechanism of accelerated leukemia development and myeloid sarcoma formation is not clear.

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In this study, we demonstrate Hoxa10 accelerated leukemia development and are the first to show that Hoxa11 controls migration and retention of leukemia cell at extramedullary sites and is a key player in myeloid sarcoma formation.

The molecular mechanism of myeloid sarcoma (MS) formation remains nuclear. Our clinical and mouse model findings from a previous study revealed that cooperation of KMT2A (MLL) translocation (MLL-t) with activating N-/K-RAS mutations promoted MS formation in a shorter latency. To improve the understanding of MS formation, in this study, we performed imaging cell trafficking analysis and demonstrated that cells harboring cooperating mutations migrated more slowly to omental adipose tissues and more cells were retained in adipose tissues in vivo. Comparison of transcriptome profiling among three pairs of mouse MLL/AF10(OM-LZ) leukemia cell lines harboring activating and wild-type KRAS identified 77 differentially expressed genes (DEGs) with >1.5-fold change. Functional annotation of these 77 DEGs using Gene Ontology (GO) enrichment analysis followed by cluster analysis revealed that GO terms related to development/differentiation have the highest enrichment score. The roles of Hoxa10 and Hoxa11, two genes which mapped to this cluster, were further characterized. Silencing Hoxa10 and Hoxa11 in cells harboring cooperating mutations prolonged the survival and reduced MS formation, respectively, in the recipient mice. Data of imaging cell trafficking as well as competitive engraftment and clonal expansion analyses indicated that silencing or overexpressing Hoxa11 in mouse leukemia cells affected cell migration and retention in omental adipose tissue. Although silencing Hoxa11 in leukemia cells did not affect Cxcr4 expression, it resulted in increased transwell migration, motility in confined spaces 3 μm in size, and cell protrusion. Our results revealed that Hoxa10 plays an important role in survival and Hoxa11 contributes to MS formation in MLL-t acute myeloid leukemia with activating KRAS mutation.

Distinctive Flow Cytometric and Mutational Profile of Acute Myeloid Leukemia With t(8;16)(p11;p13) Translocation

OBJECTIVES

Acute myeloid leukemia (AML) with t(8;16)(p11;p13) abnormalities is a rare, aggressive, and diagnostically challenging subtype that results in KAT6A-CREBBP gene fusion.

METHODS

To investigate their immunophenotype and genomic features, we identified 5 cases of AML with t(8;16) through a retrospective review of the databases at Northwestern Memorial Hospital in Chicago, IL, and Washington University Medical Center, in St Louis, MO.

RESULTS

In all, 4 of 5 cases were therapy related and 1 was possibly therapy related. The leukemic blasts showed distinctive features, including bright CD45 expression and remarkably high side scatter that overlapped with maturing myeloid elements, making the blasts difficult to identify on initial examination. They were positive for CD13, CD33, and CD64 and negative for CD34 and CD117. Next-generation sequencing profiling of 4 cases revealed pathogenic ASXL1 (2 cases), FLT3-tyrosine kinase domain (TKD) mutations (2 cases), and other pathogenic mutations. In 3 patients, t(8;16) was the sole cytogenetic abnormality; additional aberrations were found in 2 patients. Single nucleotide polymorphism microarray revealed 1 case with 7q deletion as a secondary clone.

CONCLUSIONS

Our data highlight the distinctive immunophenotypic profile of AML with t(8;16), which, along with its unique morphology, often presents a diagnostic challenge. We showed that mutations of either ASXL1 or FLT3-TKD are seen in most cases of this leukemia.

Straight to the Point-The Novel Strategies to Cure Pediatric AML

Although the outcome has improved over the past decades, due to improved supportive care, a better understanding of risk factors, and intensified chemotherapy, pediatric acute myeloid leukemia remains a life-threatening disease, and overall survival (OS) remains near 70%. According to French-American-British (FAB) classification, AML is divided into eight subtypes (M0-M7), and each is characterized by a different pathogenesis and response to treatment. However, the curability of AML is due to the intensification of standard chemotherapy, more precise risk classification, improvements in supportive care, and the use of minimal residual disease to monitor response to therapy. The treatment of childhood AML continues to be based primarily on intensive, conventional chemotherapy. Therefore, it is essential to identify new, more precise molecules that are targeted to the specific abnormalities of each leukemia subtype. Here, we review abnormalities that are potential therapeutic targets for the treatment of AML in the pediatric population.

Infant Acute Leukemia

Infant acute leukemia is a rare but aggressive disease. Although infant acute leukemia is cytologically and histologically similar to acute leukemia seen in older children and adults, it displays unique and characteristic clinical and genetic characteristics. The features, as well as the extremely young age of the patients, present multiple challenges for treatment. This review focuses on the unique pathology of acute leukemia of infancy, including the genetic characteristics that are specific for these diseases.

The Role of Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) offers potentially curative treatment for many children with high-risk or relapsed acute leukemia (AL), thanks to the combination of intense preparative radio/chemotherapy and the graft-versus-leukemia (GvL) effect. Over the years, progress in high-resolution donor typing, choice of conditioning regimen, graft-versus-host disease (GvHD) prophylaxis and supportive care measures have continuously improved overall transplant outcome, and recent successes using alternative donors have extended the potential application of allotransplantation to most patients. In addition, the importance of minimal residual disease (MRD) before and after transplantation is being increasingly clarified and MRD-directed interventions may be employed to further ameliorate leukemia-free survival after allogeneic HSCT. These advances have occurred in parallel with continuous refinements in chemotherapy protocols and the development of targeted therapies, which may redefine the indications for HSCT in the coming years. This review discusses the role of HSCT in childhood AL by analysing transplant indications in both acute lymphoblastic and acute myeloid leukemia, together with current and most promising strategies to further improve transplant outcome, including optimization of conditioning regimen and MRD-directed interventions.

Treatment of acute myeloid leukemia in children: A practical perspective

Pediatric acute myeloid leukemia (AML) is a heterogeneous disease that requires a multifaceted treatment approach. Although outcomes for low-risk AML have improved significantly over recent decades, high-risk AML continues to be associated with an adverse prognosis. Recent advances in molecular diagnostics, risk stratification, and supportive care have contributed to improvements in outcomes in pediatric AML. Targeted approaches, for example, the use of tyrosine kinase inhibitors to treat FLT3-ITD AML, offer promise and are currently undergoing clinical investigation in pediatric patients. New approaches to hematopoietic stem cell transplantation, including the use of haploidentical donors, are significantly expanding donor options for patients with high-risk AML. This review provides an overview of recent advances in the treatment of pediatric AML that are likely to have clinical impact and reshape the standard of care.

Molecular Genetics of Pediatric Acute Myeloid Leukemia

The genetic basis for pediatric acute myeloid leukemia (AML) is highly heterogeneous, often involving the cooperative action of characteristic chromosomal rearrangements and somatic mutations in progrowth and antidifferentiation pathways that drive oncogenesis. Although some driver mutations are shared with adult AML, many genetic lesions are unique to pediatric patients, and their appropriate identification is essential for patient care. The increased understanding of these malignancies through broad genomic studies has begun to risk-stratify patients based on their combinations of genomic alterations, a trend that will enable precision medicine in this population.

Cytogenetics of Pediatric Acute Myeloid Leukemia: A Review of the Current Knowledge

Pediatric acute myeloid leukemia is a rare and heterogeneous disease in relation to morphology, immunophenotyping, germline and somatic cytogenetic and genetic abnormalities. Over recent decades, outcomes have greatly improved, although survival rates remain around 70% and the relapse rate is high, at around 30%. Cytogenetics is an important factor for diagnosis and indication of prognosis. The main cytogenetic abnormalities are referenced in the current WHO classification of acute myeloid leukemia, where there is an indication for risk-adapted therapy. The aim of this article is to provide an updated review of cytogenetics in pediatric AML, describing well-known WHO entities, as well as new subgroups and germline mutations with therapeutic implications. We describe the main chromosomal abnormalities, their frequency according to age and AML subtypes, and their prognostic relevance within current therapeutic protocols. We focus on de novo AML and on cytogenetic diagnosis, including the practical difficulties encountered, based on the most recent hematological and cytogenetic recommendations.

Infant Acute Myeloid Leukemia: A Unique Clinical and Biological Entity

Infant acute myeloid leukemia (AML) is a rare subgroup of AML of children <2 years of age. It is as frequent as infant acute lymphoblastic leukemia (ALL) but not clearly distinguished by study groups. However, infant AML demonstrates peculiar clinical and biological characteristics, and its prognosis differs from AML in older children. Acute megakaryoblastic leukemia (AMKL) is very frequent in this age group and has raised growing interest. Thus, AMKL is a dominant topic in this review. Recent genomic sequencing has contributed to our understanding of infant AML. These data demonstrated striking features of infant AML: fusion genes are able to induce AML transformation without additional cooperation, and unlike AML in older age groups there is a paucity of associated mutations. Mice modeling of these fusions showed the essential role of ontogeny in the infant leukemia phenotype compared to older children and adults. Understanding leukemogenesis may help in developing new targeted treatments to improve outcomes that are often very poor in this age group. A specific diagnostic and therapeutic approach for this age group should be investigated.

Characteristics and outcome of patients with acute myeloid leukaemia and t(8;16)(p11;p13): results from an International Collaborative Study

In acute myeloid leukaemia (AML) t(8;16)(p11;p13)/MYST3-CREBBP is a very rare abnormality. Previous small series suggested poor outcome. We report on 59 patients with t(8;16) within an international, collaborative study. Median age was 52 (range: 16-75) years. AML was de novo in 58%, therapy-related (t-AML) in 37% and secondary after myelodysplastic syndrome (s-AML) in 5%. Cytogenetics revealed a complex karyotype in 43%. Besides MYST3-CREBBP, whole-genome sequencing on a subset of 10 patients revealed recurrent mutations in ASXL1, BRD3, FLT3, MLH1, POLG, TP53, SAMD4B (n = 3, each), EYS, KRTAP9-1 SPTBN5 (n = 4, each), RUNX1 and TET2 (n = 2, each). Complete remission after intensive chemotherapy was achieved in 84%. Median follow-up was 5·48 years; five-year survival rate was 17%. Patients with s-/t-AML (P = 0·01) and those with complex karyotype (P = 0·04) had an inferior prognosis. Allogeneic haematopoietic cell transplantation (allo-HCT) was performed in 21 (36%) patients, including 15 in first complete remission (CR1). Allo-HCT in CR1 significantly improved survival (P = 0·04); multivariable analysis revealed that allo-HCT in CR1 was effective in de novo AML but not in patients with s-AML/t-AML and less in patients exhibiting a complex karyotype. In summary, outcomes of patients with t(8;16) are dismal with chemotherapy, and may be substantially improved with allo-HCT performed in CR1.

Acute Myeloid Leukemia in Children: Emerging Paradigms in Genetics and New Approaches to Therapy

PURPOSE OF REVIEW

Acute myeloid leukemia (AML) in children remains a challenging disease to cure with suboptimal outcomes particularly when compared to the more common lymphoid leukemias. Recent advances in the genetic characterization of AML have enhanced understanding of individualized patient risk, which has also led to the development of new therapeutic strategies. Here, we review key cytogenetic and molecular features of pediatric AML and how new therapies are being used to improve outcomes.

RECENT FINDINGS

Recent studies have revealed an increasing number of mutations, including WT1, CBFA2T3-GLIS2, and KAT6A fusions, DEK-NUP214 and NUP98 fusions, and specific KMT2A rearrangements, which are associated with poor outcomes. However, outcomes are starting to improve with the addition of therapies such as gemtuzumab ozogamicin and FLT3 inhibitors, initially developed in adult AML. The combination of advanced risk stratification and ongoing improvements and innovations in treatment strategy will undoubtedly lead to better outcomes for children with AML.

Fusion genes as biomarkers in pediatric cancers: A review of the current state and applicability in diagnostics and personalized therapy

The incidence of pediatric cancers is rising steadily across the world, along with the challenges in understanding the molecular mechanisms and devising effective therapeutic strategies. Pediatric cancers are presented with diverse molecular characteristics and more distinct subtypes when compared to adult cancers. Recent studies on the genomic landscape of pediatric cancers using next-generation sequencing (NGS) approaches have redefined this field by providing better subtype characterization and novel actionable targets. Since early identification and personalized treatment strategies influence therapeutic outcomes, survival, and quality of life in pediatric cancer patients, the quest for actionable biomarkers is of great value in this field. Fusion genes that are prevalent and recurrent in several pediatric cancers are ideally suited in this context due to their disease-specific occurrence. In this review, we explore the current status of fusion genes in pediatric cancer subtypes and their use as biomarkers for diagnosis and personalized therapy. We discuss the technological advancements made in recent years in NGS sequencing and their impact on fusion detection algorithms that have revolutionized this field. Finally, we also discuss the advantages of pairing liquid biopsy protocols for fusion detection and their eventual use in diagnosis and treatment monitoring.

Uncommon cytogenetic abnormalities identifying high-risk acute myeloid leukemia in children

Pediatric acute myeloid leukemia (AML) represents an aggressive disease and is the leading cause of childhood leukemic mortality. The genomic landscape of pediatric AML has been recently mapped and redefined thanks to large-scale sequencing efforts. Today, understanding how to incorporate the growing list of genetic lesions into a risk stratification algorithm for pediatric AML is increasingly challenging given the uncertainty regarding the prognostic impact of rare lesions. Here we review some uncommon cytogenetic lesions to be considered for inclusion in the high-risk groups of the next pediatric AML treatment protocols. We describe their main clinical characteristics, biological background and outcome. We also provide some suggestions for the management of these rare but challenging patients and some novel targeted therapeutic options.

Neonatal Acute Lymphoblastic Leukemia with t(9;11) Translocation Presenting as Blueberry Muffin Baby: Successful Treatment by ALL-BFM Induction Therapy, Allogeneic Stem Cell Transplantation from an Unrelated Donor, and PCR-MRD-Guided Post-Transplant Follow-Up

Patient: Male, 3-day-old

Final Diagnosis: Neonatal leukemia

Symptoms: Skin lesions

Medication: —

Clinical Procedure: Biopsy • stem cell transplant

Specialty: Hematology • Pediatrics and Neonatology

Two rare cases of acute myeloid leukemia with t(8;16)(p11.2;p13.3) and 1q duplication: case presentation and literature review

Background

Acute myeloid leukemia (AML) is a complex hematological disease characterized by genetic and clinical heterogeneity. The identification and understanding of chromosomal abnormalities are important for the diagnosis and management of AML patients. Compared with recurrent chromosomal translocations in AML, t(8;16)(p11.2;p13.3) can be found in any age group but is very rare and typically associated with poor prognosis.

Methods

Conventional cytogenetic studies were performed among 1,824 AML patients recorded in our oncology database over the last 20 years. Fluorescence in situ hybridization (FISH) was carried out to detect the translocation fusion. Array comparative genome hybridization (aCGH) was carried out to further characterize the duplication of chromosomes.

Results

We identified three AML patients with t(8;16)(p11.2;p13.3) by chromosome analysis. Two of the three patients, who harbored an additional 1q duplication, were detected by FISH and aCGH. aCGH characterized a 46.7 Mb and 49.9 Mb gain in chromosome 1 at band q32.1q44 separately in these two patients. One patient achieved complete remission (CR) but relapsed 3 months later. The other patient never experienced CR and died 2 years after diagnosis.

Conclusion

A 1q duplication was detected in two of three AML patients with t(8;16)(p11.2;p13.3), suggesting that 1q duplication can be a recurrent event in AML patients with t(8;16). In concert with the findings of previous studies on similar patients, our work suggests that 1q duplication may also be an unfavorable prognostic factor of the disease.

HEMOPHAGOCYTOSIS BY BLASTS IN A CHILD WITH ACUTE MONOCYTIC LEUKEMIA AFTER CHEMOTHERAPY

Objective:

To describe the case of a child who presented hemophagocytic lymphohistiocytosis (HLH) associated with acute monocytic leukemia after chemotherapy, with hemophagocytosis caused by leukemic cells.

Case description:

In a university hospital in Southern Brazil, a 3-year-old female was diagnosed with acute monocytic leukemia with normal karyotype. The chemotherapy regimen was initiated, and she achieved complete remission six months later, relapsing after four months with a complex karyotype involving chromosomes 8p and 16q. The bone marrow showed vacuolated blasts with a monocytic aspect and evidence of hemophagocytosis. The child presented progressive clinical deterioration and died two months after the relapse.

Comments:

HLH is a rare and aggressive inflammatory condition characterized by cytopenias, hepatosplenomegaly, fever, and hemophagocytosis in the bone marrow, lymph nodes, spleen, and liver. Although rare, malignancy-associated HLH (M-HLH) is fatal. The patient in this case report met five out of the eight established criteria for HLH. The evolution of the patient’s karyotype, regardless of the diagnostic profile, seemed secondary to the treatment for acute monocytic leukemia. In this case, the cytogenetic instability might have influenced the abnormal behavior of leukemic cells. This is a rare case of HLH in a child with acute monocytic leukemia.

Maternal Babesia infection associated with neonatal extramedullary hematopoiesis and acute myeloid leukemia in late infancy

Background

We describe a term neonate who was exposed to maternal mid-gestation infection with Babesia microti and prenatal antimicrobic treatment with quinine, azithromycin, atovaquone, and clindamycin.

Case description

The neonate was born with a “blueberry muffin rash” and was diagnosed with extramedullary hematopoiesis (EHM) after ruling out congenital infection and malignancy. At 8 months of age, he presented with M5 acute myeloid leukemia (AML) with a t(8:16)(p11;13) translocation. This translocation is described in adult patients with treatment-related AML, suggesting sensitivity of the genome to extrinsic toxicity.

Conclusion

We postulate that the biologic stress and treatment of maternal babesiosis played a role in the development of the rare form of AML seen in our patient.

Pediatric acute myeloid leukemia: updates on biology, risk stratification, and therapy

PURPOSE OF REVIEW

Despite advances in therapy over the past decades, overall survival for children with acute myeloid leukemia (AML) has not exceeded 70%. In this review, we highlight recent insights into risk stratification for patients with pediatric AML and discuss data driving current and developing therapeutic approaches.

RECENT FINDINGS

Advances in cytogenetics and molecular profiling, as well as improvements in detection of minimal residual disease after induction therapy, have informed risk stratification, which now relies heavily on these elements. The treatment of childhood AML continues to be based primarily on intensive, conventional chemotherapy. However, recent trials focus on limiting treatment-related toxicity through the identification of low-risk subsets who can safely receive fewer cycles of chemotherapy, allocation of hematopoietic stem-cell transplant to only high-risk patients and optimization of infectious and cardioprotective supportive care.

SUMMARY

Further incorporation of genomic and molecular data in pediatric AML will allow for additional refinements in risk stratification to enable the tailoring of treatment intensity. These data will also dictate the incorporation of molecularly targeted therapeutics into frontline treatment in the hope of improving survival while decreasing treatment-related toxicity.

Erythrophagocytosis by leukemic blasts in acute myeloid leukemia with a normal karyotype and no detectable mutations

The phagocytosis of erythrocytes by leukemic blasts is a rare finding in acute myeloid leukemia and has been reported most commonly in monocytic and megakaryocytic morphologies. In the reported cases, erythrophagocytosis by leukemic blasts has been associated with t(8;16). This translocation is associated with a poor outcome independent of erythrophagocytosis. There has only been one reported case of erythrophagocytosis by leukemic blasts occurring in a patient with a normal karyotype. We report a 62-year-old woman with acute myeloid leukemia with monocytic features and a normal karyotype noted to have erythrophagocytosis by leukemic blasts.

Acute Myeloid Leukemia in an Infant with t(8;19)(p11.2;q13) Translocation: Case Report and a Review of the Literature

Acute myeloid leukemia (AML) patients with t(8;16)(p11.2;p13) constitute a small subgroup with a distinct genetic and clinical profile. We present a unique case of a female infant with monocytic AML associated with t(8;19)(p11.2;q13.3), a rarely reported variation of t(8;16)(p11.2;p13). The patient presented with leukemia cutis and demonstrated erythrophagocytosis in the diagnostic bone marrow. She responded well to standard AML chemotherapy and is currently in remission. Here, we highlight her case as the youngest AML patient with t(8;19) described in the literature, discuss the significance and prognostic implications of this genetic variant, and review 8p11.2 fusion proteins in AML.

Erythrophagocytosis by blasts in a case of de novo acute monoblastic leukemia with rare but characteristic t(8;16)

Erythrophagocytosis by leukemic blasts is a rare phenomenon. We report a case of a female diagnosed with acute monoblastic leukemia with leukemic blasts that were CD34 and CD117 negative, showing erythrophagocytosis, vacoulations, and a rare t(8;16) on bone marrow karyotype which is associated with a poor prognosis despite intensive chemotherapy. Meticulous bone marrow examination in such a scenario may point towards the presence of t(8;16) and help clinicians take a well-informed clinical decision.

Pediatric leukemia cutis: A case series

BACKGROUND

Pediatric leukemia cutis (LC) is often difficult to diagnose due to similarity in appearance to other dermatologic diseases. Several case reports and smaller case series have been published in the medical literature, but studies on larger cohorts of children with LC are lacking.

OBJECTIVE

This study aimed to better characterize the clinical features, course, and prognosis of LC in the pediatric population.

METHODS

We performed a retrospective case series of 31 patients diagnosed with LC at Boston Children's Hospital and the Children's Hospital of Philadelphia.

RESULTS

The number and morphology of LC lesions varied among patients, with the head and lower extremities being the most common sites of involvement. Leukemia cutis presented concomitantly with systemic leukemia in the majority of cases. Most cases of LC arose during initial leukemia episodes, rather than with relapsed leukemia. Acute myeloid leukemia was the subtype most frequently associated with LC, followed by acute lymphoblastic leukemia. Diagnosis altered treatment timing and therapeutic decisions.

CONCLUSION

Children most often present concomitantly with LC and systemic leukemia. Since the morphology and distribution of LC varies, physicians must maintain a high index of suspicion for this diagnosis, as the presence of LC may change the management of systemic leukemia.

Genetic Testing in the Diagnosis and Biology of Acute Leukemia

OBJECTIVES

The 2017 Workshop of the Society for Hematopathology/European Association for Haematopathology examined the role of molecular genetics in the diagnosis and biology of acute leukemia.

METHODS

Acute leukemias were reviewed in two sessions: "Genetic Testing in Diagnosis of Acute Leukemias" (53 cases) and "Genetics Revealing the Biology of Acute Leukemias" (41 cases).

RESULTS

Cases included acute lymphoblastic leukemia, acute myeloid leukemia, and acute leukemia of ambiguous lineage. Many cases demonstrated genetic alterations of known diagnostic, prognostic, and/or therapeutic significance, while others exhibited alterations that illuminated disease biology. The workshop highlighted the complexity of acute leukemia diagnosis and follow-up, while illustrating advantages and pitfalls of molecular genetic testing.

CONCLUSIONS

Our understanding of the molecular genetics of acute leukemias continues to grow rapidly. Awareness of the potential complexity of genetic architecture and environment is critical and emphasizes the importance of integrating clinical information with morphologic, immunophenotypic, and molecular genetic evaluation.

NEAT1-TFE3 and KAT6A-TFE3 renal cell carcinomas, new members of MiT family translocation renal cell carcinoma

Microphthalmia-associated transcription factor (MiT) family translocation renal cell carcinoma harbors variable gene fusions involving either TFE3 or TFEB genes. Multiple 5' fusion partners for TFE3 have been reported, including ASPSCR1, CLTC, DVL2, LUC7L3, KHSRP, PRCC, PARP14, NONO, SFPQ1, MED15, and RBM10. Each of these fusion genes activates TFE3 transcription which can be detected by immunostaining. Using targeted RNA-sequencing, TFE3 fusion gene partners were identified in 5 cases of TFE3 immunohistochemistry positive translocation renal cell carcinoma. Three cases demonstrated known fusions: ASPSCR1-TFE3, MED15-TFE3 and RBM10-TFE3. However, two cases showed unreported NEAT1-TFE3 and KAT6A-TFE3 fusion transcripts. The NEAT1-TFE3 RCC arose in a 59-year-old male; which demonstrated overlapping morphological features seen in NEAT2(MALAT1)-TFEB t(6;11) renal cell carcinoma, including biphasic alveolar/nested tumor cells with eosinophilic cytoplasm. The KAT6A-TFE3 renal cell carcinoma demonstrated typical morphological features of TFE3/Xp11 renal cell carcinoma including papillae, eosinophilic cytoplasm with focal clearing and abundant psammoma bodies. KAT6A gene fusion was reported in some cases of acute myeloid leukemia, which has not been previously reported in solid tumors. This report highlights the genetic complexity of TFE3 translocation renal cell carcinoma; and RNA-sequencing is a powerful approach for elucidating the underlying genetic alterations.

Prognostic Significance of Complex Karyotypes in Acute Myeloid Leukemia

OPINION STATEMENT

Acute myeloid leukemia (AML) patients with a complex karyotype (CK-AML) show at least 3 unrelated clonal cytogenetic abnormalities with notoriously poor outcome. Such cases fall into either AML with myelodysplasia-related changes or therapy-related AML in the current World Health Organization classification of AML. Allogeneic stem cell transplantation is one of the only treatment modalities that can provide a long-term survival benefit and is recommended as a consolidative treatment in patients who are able to achieve complete remission. Unfortunately, transplantation is also associated with a higher relapse rate and more than half of CK-AML patients relapse from disease within the first 2 years. The probability of achieving remission with traditional induction using cytarabine and daunorubicin or idarubicin ("7 + 3") is so small that investigational therapies should be considered up front in these patients. Less intensive therapeutic backbones, typically using one of the hypomethylating agents, azacitidine or decitabine, minimize toxicity and show a trend toward the improved overall survival. CPX 351 (Vyxeos) is a liposomal formulation of cytarabine and daunorubicin and this encapsulation leads to prolonged exposure to the two drugs. This drug is approved for AML patients with MDS-related changes and therapy-related AML, both of which are frequently associated with complex karyotype. Such patients show improved outcome in trials using this combination. Combination therapy that includes venetoclax (BCL2 inhibitor) with hypomethylating agents may also be appropriate for such patients.

Improved survival for children and young adolescents with acute myeloid leukemia: a Dutch study on incidence, survival and mortality

Variation in survival of pediatric acute myeloid leukemia (pAML) over time and between Western European countries exists. The aim of the current study is to assess the progress made for the Dutch pAML population (0-17 years) during 1990-2015, based on trends in incidence, survival and mortality. Data from the population-based Netherlands Cancer Registry were merged with leukemia-related characteristics and treatment specifics from the Dutch Childhood Leukemia Study Group (Dutch Childhood Oncology Group (DCOG) from 2002 onwards). Mortality data (1980-2016) were obtained from the cause of death registry of Statistics Netherlands. Trend analyses were performed over time and by treatment protocol. Between 1990 and 2015, a total of 635 children aged 0-17 years were diagnosed with AML for an average of 25 patients (range 18-36) per year. There was a slight increase in the incidence at age 1-4 years (average annual percentage change (AAPC) of +2.2% per year (95% CI 0.8-3.5, p < 0.01)). Overall, the 5-year survival significantly improved over the past 26 years and nearly doubled from 40% in the early 1990s to 74% in 2010-2015. Multivariable analysis showed a 49% reduction in risk of death for pAML patients treated according to the latest DB-AML 01 protocol (p = 0.03). The continuing decrease of mortality (AAPC -2.8% per year (95% CI -4.1 to -1.5)) supports the conclusion of true progress against pAML in the Netherlands.

Prognostic impact of t(16;21)(p11;q22) and t(16;21)(q24;q22) in pediatric AML: a retrospective study by the I-BFM Study Group

To study the prognostic relevance of rare genetic aberrations in acute myeloid leukemia (AML), such as t(16;21), international collaboration is required. Two different types of t(16;21) translocations can be distinguished: t(16;21)(p11;q22), resulting in the FUS-ERG fusion gene; and t(16;21)(q24;q22), resulting in RUNX1-core binding factor (CBFA2T3). We collected data on clinical and biological characteristics of 54 pediatric AML cases with t(16;21) rearrangements from 14 international collaborative study groups participating in the international Berlin-Frankfurt-Münster (I-BFM) AML study group. The AML-BFM cohort diagnosed between 1997 and 2013 was used as a reference cohort. RUNX1-CBFA2T3 (n = 23) had significantly lower median white blood cell count (12.5 × 10⁹/L, P = .03) compared with the reference cohort. FUS-ERG rearranged AML (n = 31) had no predominant French-American-British (FAB) type, whereas 76% of RUNX1-CBFA2T3 had an M1/M2 FAB type (M1, M2), significantly different from the reference cohort (P = .004). Four-year event-free survival (EFS) of patients with FUS-ERG was 7% (standard error [SE] = 5%), significantly lower compared with the reference cohort (51%, SE = 1%, P < .001). Four-year EFS of RUNX1-CBFA2T3 was 77% (SE = 8%, P = .06), significantly higher compared with the reference cohort. Cumulative incidence of relapse was 74% (SE = 8%) in FUS-ERG, 0% (SE = 0%) in RUNX1-CBFA2T3, compared with 32% (SE = 1%) in the reference cohort (P < .001). Multivariate analysis identified both FUS-ERG and RUNX1-CBFA2T3 as independent risk factors with hazard ratios of 1.9 (P < .0001) and 0.3 (P = .025), respectively. These results describe 2 clinically relevant distinct subtypes of pediatric AML. Similarly to other core-binding factor AMLs, patients with RUNX1-CBFA2T3 rearranged AML may benefit from stratification in the standard risk treatment, whereas patients with FUS-ERG rearranged AML should be considered high-risk.

Classification of pediatric acute myeloid leukemia based on miRNA expression profiles

Pediatric acute myeloid leukemia (AML) is a heterogeneous disease with respect to biology as well as outcome. In this study, we investigated whether known biological subgroups of pediatric AML are reflected by a common microRNA (miRNA) expression pattern. We assayed 665 miRNAs on 165 pediatric AML samples. First, unsupervised clustering was performed to identify patient clusters with common miRNA expression profiles. Our analysis unraveled 14 clusters, seven of which had a known (cyto-)genetic denominator. Finally, a robust classifier was constructed to discriminate six molecular aberration groups: 11q23-rearrangements, t(8;21)(q22;q22), inv(16)(p13q22), t(15;17) (q21;q22), NPM1 and CEBPA mutations. The classifier achieved accuracies of 89%, 95%, 95%, 98%, 91% and 96%, respectively. Although lower sensitivities were obtained for the NPM1 and CEBPA (32% and 66%), relatively high sensitivities (84%−94%) were attained for the rest. Specificity was high in all groups (87%−100%). Due to a robust double-loop cross validation procedure employed, the classifier only employed 47 miRNAs to achieve the aforementioned accuracies. To validate the 47 miRNA signatures, we applied them to a publicly available adult AML dataset. Albeit partial overlap of the array platforms and molecular differences between pediatric and adult AML, the signatures performed reasonably well. This corroborates our claim that the identified miRNA signatures are not dominated by sample size bias in the pediatric AML dataset. In conclusion, cytogenetic subtypes of pediatric AML have distinct miRNA expression patterns. Reproducibility of the miRNA signatures in adult dataset suggests that the respective aberrations have a similar biology both in pediatric and adult AML.

C-terminal BRE overexpression in 11q23-rearranged and t(8;16) acute myeloid leukemia is caused by intragenic transcription initiation

Overexpression of the BRE (brain and reproductive organ-expressed) gene defines a distinct pediatric and adult acute myeloid leukemia (AML) subgroup. Here we identify a promoter enriched for active chromatin marks in BRE intron 4 causing strong biallelic expression of a previously unknown C-terminal BRE transcript. This transcript starts with BRE intron 4 sequences spliced to exon 5 and downstream sequences, and if translated might code for an N terminally truncated BRE protein. Remarkably, the new BRE transcript was highly expressed in over 50% of 11q23/KMT2A (lysine methyl transferase 2A)-rearranged and t(8;16)/KAT6A-CREBBP cases, while it was virtually absent from other AML subsets and normal tissues. In gene reporter assays, the leukemia-specific fusion protein KMT2A-MLLT3 transactivated the intragenic BRE promoter. Further epigenome analyses revealed 97 additional intragenic promoter marks frequently bound by KMT2A in AML with C-terminal BRE expression. The corresponding genes may be part of a context-dependent KMT2A-MLLT3-driven oncogenic program, because they were higher expressed in this AML subtype compared with other groups. C-terminal BRE might be an important contributor to this program because in a case with relapsed AML, we observed an ins(11;2) fusing CHORDC1 to BRE at the region where intragenic transcription starts in KMT2A-rearranged and KAT6A-CREBBP AML.