Acute myeloid leukemia with myelodysplasia related changes

2017-01-01   Andreas Neubauer , Alexandra Nagy 

1.Howard Hughes Medical Institute and the Department Pathology, Beckman Center for Molecular and Genetic Medicine, Stanford University, Stanford, California 94305, USA; anagy2@stanford.edu (A Na); Dept. Internal Medicine and Hematology, Oncology and Immunology, Philipps University Marburg,Germany; neubauer@staff.uni-marburg.de (A Ne)

Abstract

Acute myeloid leukemia (AML) is a heterogeneous clonal disorder with two prominent features: i) hematopoietic progenitor cells loose the ability to differentiate normally and ii) the transformed leukemia cells show an impaired regulation of myeloid proliferation.

Clinics and Pathology

Disease

Acute myeloid leukemia with myelodysplasia related changes (AML-MRC) is a subgroup of AML. It was introduced in 2008 by the WHO classification and updated in 2016 (Weinberg et al., 2015). A diagnosis of AML-MRC requires ≥ 20% blasts and additionally one of the following three criteria:
  • history of myelodysplastic syndrome (MDS) or myelodysplastic/myeloproliferative neoplasm (MDS/MPN)
  • MDS-related cytogenetic abnormalities or
  • multilineage dysplasia (≥ 50% dysplastic cells in≥ two hematopoietic lineages) (Arber et al., 2016a).
  • Etiology

    There are various risk factors which can cause AML in general. These risk factors can be categorized as genetic disorders, physical and chemical exposure, radiation therapy and chemotherapy. Even though many people are exposed, to various degrees, to carcinogens, only a few cases may present with a known history of carcinogen exposure. Currently, it is not fully understood why some people develop AML and some do not (Estey and Döhner, 2006). Genetically, many researchers favor the "two-hit" hypothesis first proposed by Hartmut Beug (Beug et al., 1978), and later by Gary Gilliland. This hypothesis states that for transformation, a mutation in a kinase coding gene such as RAS, KIT or FLT3 has to occur together with a class II mutation targeting a transcription of nuclear factor such as NPM1, RUNX1 or CEBPA. Today, we know about a high variation of somatic mutations and chromosomal abnormalities characterizing different types of AML. AML-MRC is often associated with the following chromosomal abnormalities (Table 1) (Deschler et al., 2006; Weinberg et al., 2015).

    Epidemiology

    If the WHO classification is strictly applied, 48% of all adult AML cases meet the AML-MRC criteria. It tends to affect more male and is a disease of the elderly with a median age of 68 years. Additionally, it is associated with a higher frequency of unfavorable cytogenetics and, consequently, a worse clinical outcome (Davis et al.,2013; Xu et al., 2014; Weinberg et al., 2009). AML-MRC occurs more often de novo then secondary to myelodysplasia (Vardiman and Reichard, 2015).

    Cytology

    AML-MRC cases commonly present with multilineage dysplasia. This is validated best with peripheral blood smears or bone marrow smears for identifying myeloid and erythroid dysplasia and bone marrow biopsy for identifying megakaryocytic dysplasia (Falini et al., 2016). Following the WHO classification an AML-MRC presents with ≥ 50 % dysplastic cells in at least two hematopoietic lineages. The dysplastic features are not unique for AML-MRC, but can be also detected in other hematopoietic diseases, such as MDS (Wu et al., 2013). Dysplastic neutrophils may exhibit a nucleus-cytoplasm dysynchrony, hypogranulation and abnormal nuclear segmentation (pseudo-Pelger-Huët anomaly), e.g. bi-nucleated segments (Weinberg et al., 2015). As mentioned, dyserythropoesis and dysmegakaryopoesis are also commonly seen. Dyserythropoesis presents with odd erythroid precusors and sometimes ring sideroblasts, as well as multinuclearity, megaloblastoid changes and karyorrhexis. Dysmegakaryopoesis commonly shows hypolobulated micromegakaryocytes, non-lobulated nuclei in megakaryocytes of all sizes and multiple widely separated nuclei (Wakui et al., 2008).

    Other features

    Immunophenotype: Because of the heterogeneity and commonly associated cytogenetic abnormalities AML-MRC has no specific immunophenotypic profile. However, the immunophenotype of blasts exhibits similar characteristics as seen in MDS (Ayar et al., 2014). Antigens associated with myeloid differentiation, such as MPO, CD33, CD13, CD64, CD14 and CD15 are seen in various degrees (van Dongen et al., 2012). MDS related AMLs with monocytic differentiation also show expression of CD45 and lack CD34 (Van Dongen et al., 2012). Additionally, the aberrant expression of CD10, CD56 and CD7 in blasts may be found (Weinberg et al., 2016). AML-MRC cases associated with monosomy 5 or 7 may show aberrant expression of TDT and CD7 (Font et al., 2006).

    Treatment

    The therapy of AML-MRC is based on regular AML-therapy with a risk-adapted chemotherapy including induction chemotherapy ("7+3"; daunorubicine plus cytarabine) and postinduction therapy, such as high-dose cytarabine or in high-risk patients, allogeneic transplantation in first remission. Using regular assessments, lab studies including cytogenetics and molecular analyses, the patient can be assigned to a risk group and treatment and prognosis can be determined and the decision between curative chemotherapy/allogeneic stem cell transplantation, palliative chemotherapy and best supportive care can be made (Estey and Döhner, 2006). Chemotherapy can be separated into two main parts. First, the induction therapy with the attempt to reach complete remission. Second, the consolidation therapy to prolong the complete remission. If the patient displays characteristics of high risk AML, a hematopoietic stem cell transplantation (HSCT) must be considered (Kumar, 2011). As AML-MRC frequently fulfills the high-risk criteria such as: 3(q21q26) abnormalities, RPN1/MECOM (EVI1), del(5q), del(7q), t(6;9), other 11q23 abnormalities, 17p abnormalities, or complex aberrant karyotypes described as at least 3 unrelated abnormalities excluding cases with t(8;21), inv(16), and t(15;17), an allogeneic stem cell transplantation will be the post-induction therapy of first choice in most adults (Vardiman and Reichard, 2015).

    Prognosis

    The myelodysplastic changes and MDS associated chromosomal abnormalities of AML-MRC are associated with a worse prognosis and lower rates of event-free survival and overall survival. However, it was shown that there is no difference in prognosis between patients with AML-MRC with a history of MDS and the remaining cases of AML-MRC (Weinberg et al., 2009; Arber et al., 2003). Besides, AML-MRC with the absence of cytogenetic abnormalities seem to have a better prognosis (Weinberg et al., 2009). Additionally, AML-MRC with NPM1 mutations and with or without cytogenetic abnormalities show a better prognosis (Haferlach et al., 2009). This was also shown for CEBPA mutations (Vardiman and Reichard, 2015). Therefore AML-MRC with NPM1 or CEBPA mutations are excluded from the AML-MRC category in the WHO classification 2016 (Arber et al., 2016). The prognosis of AML-MRC particularly in context of multilineage dysplasia remains controversial (Vardiman and Reichard, 2015). In patients who have undergone allogenic HSCT there is no prognostic difference in AML-MRC patients compared to AML not otherwise specified (AML-NOS) (Ikegawa et al., 2016).

    Cytogenetics

    Atlas Image
    Figure 1. Karyotype analysis with MDS related cytogenetic abnormalities: 46,XX,t(4;6)(q21;23),del(5)(q11.2q35),del(7)(q11.2q36),+8,add(11)(p15),del(12)(p12p13),-17. Commonly seen in MDS is the deletion of 5 and 7 (stars) and/or monosomy 17 (cross) (Miesner et al., 2010).

    Genes Involved and Proteins

    Note
    As mentioned in Prognosis, the NPM1 mutation can present with multilineage dysplasia and is associated with a better outcome. However, there are no genetic somatic mutations fully specific for AML-MRC. As the subcategory AML-MRC represents almost 50% of all AML cases there can be found all common somatic mutations of AML concomitantly. In case of an AML-MRC with a history of MDS commonly mutated genes in MDS should also be considered, e.g. SF3B1 which is associated with the formation of ring sideroblasts in MDS (Malcovati et al., 2014). Somatic mutations have prognostic value and are assumed to play a critical role in leukemogenesis. They can affect signal transduction, DNA methylation, chromatin modification, transcriptional regulation, RNA splicing and cohesion- complexes. The most commonly mutated genes in AML are FLT3, NPM1, CEBPA besides many more (Cancer and Atlas, 2013; Malcovati et al., 2014). Following the 2016 WHO classification an AML-MRC with presence of NPM1 and bi-allelic CEBPA mutation is not considered a AML-MRC anymore as these gene mutations are associated with a better outcome (Arber et al., 2003; Haferlach et al., 2009; Pabst et al., 2009) In contrast FLT3 mutations are associated with genetic abnormalities and a worse clinical outcome (Bibault et al., 2015).

    Bibliography

    Pubmed IDLast YearTitleAuthors
    270692542016The 2016 revision to the World Health Organization classification of myeloid neoplasms and acute leukemia.Arber DA et al
    127602852003Prognostic impact of acute myeloid leukemia classification. Importance of detection of recurring cytogenetic abnormalities and multilineage dysplasia on survival.Arber DA et al
    246954672014Granulocyte, monocyte and blast immunophenotype abnormalities in acute myeloid leukemia with myelodysplasia-related changes.Ayar SP et al
    260783552015Next-generation sequencing of FLT3 internal tandem duplications for minimal residual disease monitoring in acute myeloid leukemia.Bibault JE et al
    236349962013Genomic and epigenomic landscapes of adult de novo acute myeloid leukemia.Ley TJ et al
    241361652013The genetic basis of myelodysplasia and its clinical relevance.Cazzola M et al
    236901272013Pediatric acute myeloid leukemia as classified using 2008 WHO criteria: a single-center experience.Davis KL et al
    170197342006Acute myeloid leukemia: epidemiology and etiology.Deschler B et al
    171267232006Acute myeloid leukaemia.Estey E et al
    202032662010Multilineage dysplasia has no impact on biologic, clinicopathologic, and prognostic features of AML with mutated nucleophosmin (NPM1).Falini B et al
    164179222006Evaluation of CD7 and terminal deoxynucleotidyl transferase (TdT) expression in CD34+ myeloblasts from patients with myelodysplastic syndrome.Font P et al
    194298692009AML with mutated NPM1 carrying a normal or aberrant karyotype show overlapping biologic, pathologic, immunophenotypic, and prognostic features.Haferlach C et al
    239067122013Structural and functional properties of platelet-derived growth factor and stem cell factor receptors.Heldin CH et al
    260842042016Allogeneic hematopoietic stem cell transplant overcomes poor prognosis of acute myeloid leukemia with myelodysplasia-related changes.Ikegawa S et al
    217794832011Genetic abnormalities and challenges in the treatment of acute myeloid leukemia.Kumar CC et al
    204715132010Detection of t(3;5) and NPM1/MLF1 rearrangement in an elderly patient with acute myeloid leukemia: clinical and laboratory study with review of the literature.Lim G et al
    249709332014Driver somatic mutations identify distinct disease entities within myeloid neoplasms with myelodysplasia.Malcovati L et al
    205813092010Multilineage dysplasia (MLD) in acute myeloid leukemia (AML) correlates with MDS-related cytogenetic abnormalities and a prior history of MDS or MDS/MPN but has no independent prognostic relevance: a comparison of 408 cases classified as "AML not otherwise specified" (AML-NOS) or "AML with myelodysplasia-related changes" (AML-MRC).Miesner M et al
    192770352009Heterogeneity within AML with CEBPA mutations; only CEBPA double mutations, but not single CEBPA mutations are associated with favourable prognosis.Pabst T et al
    219171542011Current findings for recurring mutations in acute myeloid leukemia.Takahashi S et al
    225520072012EuroFlow antibody panels for standardized n-dimensional flow cytometric immunophenotyping of normal, reactive and malignant leukocytes.van Dongen JJ et al
    260714602015Acute Myeloid Leukemia With Myelodysplasia-Related Changes.Vardiman J et al
    273879882017Assessment of myeloid and monocytic dysplasia by flow cytometry in de novo AML helps define an AML with myelodysplasia-related changes category.Weinberg OK et al
    191315462009Clinical characterization of acute myeloid leukemia with myelodysplasia-related changes as defined by the 2008 WHO classification system.Weinberg OK et al
    237378742013Characteristics of the four subtypes of myelodysplastic/myeloproliferative neoplasms.Wu H et al
    248618482014Characteristics of acute myeloid leukemia with myelodysplasia-related changes: A retrospective analysis in a cohort of Chinese patients.Xu XQ et al
    274969682017Acute leukaemia and myelodysplastic syndromes with chromosomal rearrangement involving 11q23 locus, but not MLL gene.Zuo W et al

    Citation

    Andreas Neubauer ; Alexandra Nagy

    Acute myeloid leukemia with myelodysplasia related changes

    Atlas Genet Cytogenet Oncol Haematol. 2017-01-01

    Online version: http://atlasgeneticsoncology.org/haematological/2041/acute-myeloid-leukemia-with-myelodysplasia-related-changes

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