Chronic myelomonocytic leukemia with nucleophosmin (NPM1) mutation

Nucleophosmin (NPM1) mutations in chronic myelomonocytic leukemia (CMML) are extremely uncommon, and the clinicopathologic features of these neoplasms are poorly characterized. Over a 10‐yr interval, NPM1 mutation analysis was performed in 152 CMML at our institution. NPM1 mutations were identified in 8 (5.3%) patients, five men and three women, with a median age of 72 yr (range, 27–87). In all patients, the bone marrow was hypercellular with multilineage dysplasia, monocytosis, and retained maturation supporting a diagnosis of CMML. NPM1 mutation allele burden was <5% in two patients and >10% in six patients. Four (50%) patients, all with >10% NPM1, progressed AML with a median interval of 11 months (range, 1–21). Compared with 144 CMML without NPM1 mutations, CMML patients with NPM1 mutation presented with more severe anemia (P = 0.053), higher BM monocyte percentage (P = 0.033), and an increased tendency for AML progression (P = 0.088) and an inferior overall survival (P = 0.076). Mutations involving NRAS/KRAS (2/7), TET2(2/5), ASXL1(1/5,) and FLT3(0/8) were not significantly different between these two groups. In summary, CMML with NPM1 mutation shows histopathological features of CMML, but patients appear to have a high probability for AML progression and may require aggressive clinical intervention, especially in patients with a high mutation burden.     

Transition of polycythemia vera to chronic myeloid leukaemia

A 77-year-old female with polycythemia vera (PV) showed a sudden, typical chronic myeloid leukaemia (CML), 8 yr after the initial diagnosis, and an intermittent treatment with hydroxyurea (0.5-1 g/d) and phlebotomies. At PV diagnosis, the Ph chromosome was negative and no bcr-abl rearrangement was observed; they were both revealed positive at CML onset. Transition of PV to CML is very rare; only seven substantiated cases had been reported in the literature up until now (six from 1964 to 1993). All patients but one received (32)P or alkylating agents for PV treatment. The pathogenetic mechanisms are briefly discussed.     

Blood outgrowth endothelial cells from chronic myeloid leukaemia patients are BCR/ABL1 negative

The existence of adult haemangioblasts with dual haematopoietic and endothelial developmental potential was confirmed after detection of Ph⁺ vascular endothelial cells in chronic myeloid leukaemia (CML) patients. Blood outgrowth endothelial cells (OECs) from CML patients were found not to harbour the Philadelphia translocation and were thus not clonally related to BRC/ABL1 ⁺ hematopoietic progenitors, but comprised a distinct subfraction of endothelial cells. Remarkably, the frequency of CML-derived OECs was 9-fold higher as compared to healthy donors ( n  = 19 and n  = 300, respectively; P  <   0·0001) and these cells showed increased proliferative potential, possibly reflecting the mobilisation of OEC progenitors by pro-angiogenic cytokines.     

MicroRNAs in myeloid malignancies

MicroRNAs (miRNAs) are key to the pathogenesis of human malignancies and increasingly recognized as potential biomarkers and therapeutic targets. Haematological malignancies, being the earliest human malignancies linked to aberrant miRNA expression, have consistently underpinned our understanding of the role that miRNAs play in cancer development. Here, we review the expanding roles attributed to miRNAs in the pathogenesis of different types of myeloid malignancies and highlight key findings.     

Ribosome‐associated nucleophosmin 1: increased expression and shuttling activity distinguishes prognostic subtypes in chronic lymphocytic leukaemia

Two distinct groups of chronic lymphocytic leukaemia (CLL) are distinguished by the presence or absence of somatic hypermutation of the immunoglobulin heavy‐chain gene. CLL without somatic hypermuataion has an adverse outcome, but the precise biological differences that underlie this more aggressive clinical‐course are unclear. Using a proteomic approach, we found that the two prognostic forms of CLL were consistently distinguished according to their protein expression pattern. The most important difference observed related to the different expression of nucleophosmin 1 between the two forms of CLL. This different expression was not related to apoptosis, proliferation or gene mutation. However, co‐immunoprecipitation experiments identified an association between nucleophosmin 1 and ribosomal proteins. Using immunocytofluorescence, nucleophosmin 1 expression was identified in the nucleoli and nucleoplasm of all cells, but in a proportion of cells, nucleophosmin had been transferred from the nucleoplasm to the cytoplasm. Both the fluorescent intensity, and the frequency of cytoplasmic nucleophosmin 1 expression, was higher in CLL without somatic hypermutation. We propose therefore, that nucleophosmin 1, in association with ribosomal proteins, undergoes nucleo‐cytoplasmic shuttling in CLL. This process is most prominent in un‐mutated CLL and may signify altered protein biosynthesis.     

Rapid and sensitive screening for CEBPA mutations in acute myeloid leukaemia

The presence of CCAAT/enhancer binding protein alpha (CEBPA) gene mutations in patients with cytogenetically normal acute myeloid leukaemia (CN-AML) confers a favourable prognosis. Routine screening of all CN-AML patients for CEBPA mutations is therefore important for individual risk-adapted post-remission therapy and requires a fast and easy screening method. CEBPA mutations are distributed over the entire CEBPA gene and the functional and clinical consequences of the different mutations are still largely unknown. Therefore, we developed a multiplex polymerase chain reaction-based fragment length analysis mutation screening method for the entire CEBPA coding region. We initially evaluated our method by analysing 120 CN-AML samples both by fragment analysis and nucleotide sequencing and reached a sensitivity of 100% and a specificity of 90%. 349 CN-AML samples were subsequently screened for CEBPA mutations by fragment length analysis. Among a total of 469 CN-AML patient samples, 58 CEBPA mutations were detected in 38 CN-AML patients (8.1%). In conclusion, we established a fast and sensitive CEBPA mutation screening method suitable for inclusion in routine AML diagnostics.     

Identification of relapse-associated gene mutations by next-generation sequencing in low-risk acute myeloid leukaemia patients

Recommended genetic categorization of acute myeloid leukaemias (AML) includes a favourable-risk category, but not all these patients have good prognosis. Here, we used next-generation sequencing to evaluate the mutational profile of 166 low-risk AML patients: 30 core-binding factor (CBF)-AMLs, 33 nucleophosmin (NPM1)-AMLs, 4 biCEBPα-AMLs and 101 acute promyelocytic leukaemias (APLs). Functional categories of mutated genes differed among subgroups. NPM1-AMLs showed frequent variations in DNA-methylation genes (DNMT3A, TET2, IDH1/2) (79%), although without prognostic impact. Within this group, splicing-gene mutations were an independent factor for relapse-free (RFS) and overall survival (OS). In CBF-AML, poor independent factors for RFS and OS were mutations in RAS pathway and cohesin genes, respectively. In APL, the mutational profile differed according to the risk groups. High-risk APLs showed a high mutation rate in cell-signalling genes (P = 0·002), highlighting an increased incidence of FLT3 internal tandem duplication (ITD) (65%, P < 0·0001). Remarkably, in low-risk APLs (n = 28), NRAS mutations were strongly correlated with a shorter five-year RFS (25% vs. 100%, P < 0·0001). Overall, a high number of mutations (≥3) was the worst prognostic factor RFS (HR = 2·6, P = 0·003). These results suggest that gene mutations may identify conventional low-risk AML patients with poor prognosis and might be useful for better risk stratification and treatment decisions.     

Cancer in relatives of children with myelodysplastic syndrome, acute and chronic myeloid leukaemia

Familial myelodysplastic syndrome (MDS) has been claimed to account for as many as one third of children with MDS, especially among those showing monosomy 7. The present study is the first to provide population-based estimates of the risk of haematological and other malignancies in relatives of children with MDS. The study was extended to include children with acute myeloid leukaemia (AML) and chronic myeloid leukaemia (CML). The index group consisted of 46 children with MDS, 62 with AML, and eight with CML, which is thought to represent all myeloid leukaemias in Danish children, 1980–91. By linkage to the Central Population Register we identified parents (230), siblings (231), grandparents (151), aunts and uncles (132) and cousins (140). Information on the cancer incidence was obtained from the Danish Cancer Registry. 27 cancers were observed versus 26.7 expected (relative risk 1.0). Leukaemia in relatives was observed in only one family. None of 11 children with MDS and monosomy 7 had family members affected by leukaemia. We found no evidence of an increased overall risk of cancer in the relatives. The risk of familial MDS may be considerably lower than previously estimated.     

Clinical features at diagnosis in 430 patients with chronic myeloid leukaemia seen at a referral centre over a 16-year period

To determine major presenting features of chronic myeloid leukaemia (CML) in current practice, we have reviewed the records of 430 patients with CML referred to the Hammersmith Hospital for allogeneic bone marrow transplantation since 1981. Approximately 20% of cases were diagnosed incidentally. Symptoms such as fatigue and weight loss were associated with greater degrees of leucocytosis and splenomegaly and lower haemoglobin levels. Most bleeding patients had normal or elevated platelet counts, suggesting that platelet dysfunction was the primary cause of haemorrhage. Although thrombocytosis was common, thrombosis was not seen. Male patients and the relatively young presented with higher WBC counts and larger spleens. The reason that these groups were diagnosed with more advanced leukaemia is not clear. Although retrospective and limited to a select group of relatively young patients, this is the largest series to be reported on CML at diagnosis, and the first such report in modern clinical practice.     

Gene probe analysis demonstrates independent clonal evolution of co-existent chronic myeloid and chronic lymphocytic leukaemia

We describe a case of Philadelphia-positive chronic myeloid leukaemia occurring simultaneously with B-cell chronic lymphocytic leukaemia in a 69-yr-old male. Gene probe analysis of DNA from both peripheral blood and bone marrow provided evidence for the independent evolution of 2 clones in this case, with a predominant population showing immunoglobulin heavy chain gene rearrangement and a smaller population showing a rearrangement within the breakpoint cluster region of chromosome 22.