Summary Diagnosis of essential thrombocythaemia (ET) is challenging in patients lacking JAK2 / CALR / MPL mutations. In a retrospective evaluation of 320 patients with ‘triple‐negative ...thrombocytosis’, we assessed utility of bone marrow histology (90.9% of patients) and myeloid gene panel (MGP, 55.6%). Supportive histology (‘myeloproliferative neoplasm‐definite/probable’, 36.8%) was associated with higher platelet counts and varied between centres. 14.6% MGP revealed significant variants: 3.4% JAK2 / CALR / MPL and 11.2% other myeloid genes. Final clinical diagnosis was strongly predicted by histology, not MGP. 23.7% received cytoreduction (17.6% under 60 years). Real‐world ‘triple‐negative’ ET diagnosis currently depends heavily on histology; we advocate caution in MGP‐negative cases and that specific guidelines are needed.
The JAK2 V617F mutation is present in the majority of patients with a myeloproliferative neoplasm (MPN) and is sufficient to recapitulate an MPN in murine models. However, the consequences of JAK2 ...mutations for myeloid differentiation are poorly understood. After systematic analyses of a large cohort of JAK2-mutated MPN patients, we demonstrate in vivo that JAK2 mutations do not alter hematopoietic stem and progenitor cell com-partment size or in vitro behavior but generate expansion of later myeloid differentiation compartments, where homozygous expression of the mutation confers an added proliferative advantage at the single-cell level. In addition, we demonstrate that these findings may be partially explained by the expression pattern of JAK2, which markedly increases on myeloid differentiation. Our findings have potential clinical relevance, as they predict that JAK2 inhibitors may control myeloproliferation, but may have limited efficacy in eradicating the leukemic stem cells that sustain the human MPN.
Acute promyelocytic leukaemia (APML) can be promptly diagnosed by detecting abnormal diffuse staining patterns of PML bodies in abnormal promyelocytes using immunofluorescence microscopy. However, ...this technique is subjective, with low sensitivity. Using samples from 18 patients with acute myeloid leukaemia (AML) (including four with APML), the authors investigated whether imaging flow cytometry could be a viable alternative to this current technique and improve sensitivity levels. Bone marrow/peripheral blood cells were stained with an antibody to PML, and data were acquired on an ImageStream (Amnis Corporation, Seattle, Washington, USA). Using the modulation feature for data analysis, the authors demonstrated that this technique could successfully identify cases of APML. Imaging flow cytometry, by analysing greater numbers of cells and with the potential to include disease-specific antigens, increases the sensitivity of the current immunofluorescence technique. Imaging flow cytometry is an exciting technology that has many possible applications in the diagnosis of haematological malignancies, including the potential to integrate modalities.
Recurrent chromosomal translocations involving the mixed lineage leukaemia (MLL) gene initiate aggressive forms of leukaemia, which are often refractory to conventional therapies. Many MLL-fusion ...partners are members of the super elongation complex (SEC), a critical regulator of transcriptional elongation, suggesting that aberrant control of this process has an important role in leukaemia induction. Here we use a global proteomic strategy to demonstrate that MLL fusions, as part of SEC and the polymerase-associated factor complex (PAFc), are associated with the BET family of acetyl-lysine recognizing, chromatin 'adaptor' proteins. These data provided the basis for therapeutic intervention in MLL-fusion leukaemia, via the displacement of the BET family of proteins from chromatin. We show that a novel small molecule inhibitor of the BET family, GSK1210151A (I-BET151), has profound efficacy against human and murine MLL-fusion leukaemic cell lines, through the induction of early cell cycle arrest and apoptosis. I-BET151 treatment in two human leukaemia cell lines with different MLL fusions alters the expression of a common set of genes whose function may account for these phenotypic changes. The mode of action of I-BET151 is, at least in part, due to the inhibition of transcription at key genes (BCL2, C-MYC and CDK6) through the displacement of BRD3/4, PAFc and SEC components from chromatin. In vivo studies indicate that I-BET151 has significant therapeutic value, providing survival benefit in two distinct mouse models of murine MLL-AF9 and human MLL-AF4 leukaemia. Finally, the efficacy of I-BET151 against human leukaemia stem cells is demonstrated, providing further evidence of its potent therapeutic potential. These findings establish the displacement of BET proteins from chromatin as a promising epigenetic therapy for these aggressive leukaemias.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In a recent interesting article, analysis of gene expression between phenotypically defined acute myeloid leukemia (AML) leukemia stem cells (LSCs) and more mature leukemia progenitor cells is used ...to generate a differentially expressed gene signature for LSCs. Through clever bioinformatic weighting analysis, the authors describe a method to convert this signature into a single score for any given sample and then test the prognostic utility of this 'LSC score' in publicly available gene expression profiles from bulk AML samples. They demonstrate that a high LSC score is associated with poor prognosis in AML patients and further demonstrate that the score is independent of known prognostic factors, including age, karyotype and mutation of the FLT3 or NPM1 genes. These findings are important and directly relate transcriptional dysregulation in AML LSCs with the outcome in patient samples, thus reinforcing the belief that these cellular populations are crucial for the initial propagation and subsequent relapse and resistance of leukemia.
Immunophenotyping was introduced into diagnostic pathology over 30 years ago to assist in the diagnosis and classification of lymphoproliferative disorders. Today the role of immunophenotyping has ...been expanded beyond this to include the detection of markers of prognosis, determination of disease phenotypes associated with specific chromosomal abnormalities, detection of targets for immunotherapy and to monitor residual disease. Immunoperoxidase detection methods remain the most popular in histopathology, whilst flow cytometry is most commonly applied for haematological samples. The range of monoclonal antibodies available, including those which work in routinely performed tissue specimens, continues to increase. This is in part a result of gene expression studies identifying precise genetic signatures for certain lymphopro-liferative disorders and the generation of new protein markers to gene products of upregulated genes. This review summarises the current status and applications of immuno-phenotyping in the assessment of many of the lymphoid malignancies.
Summary
Sialic acid‐binding immunoglobulin‐like lectin (Siglec)‐15 has recently been identified as a critical tumour checkpoint, augmenting the expression and function of programmed death‐ligand 1. ...We raised a monoclonal antibody, A9E8, specific for Siglec‐15 using phage display. A9E8 stained myeloid leukaemia cell lines and peripheral cluster of differentiation (CD)33+ blasts and CD34+ leukaemia stem cells from patients with acute myeloid leukaemia (AML). By contrast, there was minimal expression on healthy donor leucocytes or CD34+ stem cells from non‐AML donors, suggesting targeting Siglec‐15 may have significant therapeutic advantages over its fellow Siglec CD33. After binding, A9E8 was rapidly internalised (half‐life of 180 s) into K562 cells. Antibodies to Siglec‐15 therefore hold therapeutic potential for AML treatment.
We present two cases where argatroban was successfully used in patients with acute thrombosis requiring anticoagulant treatment where heparin resistance with unfractionated heparin had been ...encountered. The first case was a woman with abdominal arterial thrombosis, of unknown cause, treated with therapeutic low molecular weight heparin that developed pulmonary embolism despite therapeutic anticoagulation (and had evidence of heparin resistance on anti-Xa monitoring). The second patient had provoked abdominal arterial thrombosis from sepsis and could not attain therapeutic anticoagulation with intravenous unfractionated heparin. In both cases therapeutic anticoagulation was achieved with the use of argatroban, as a temporizing measure to treat the acute thrombotic event. Conventionally, argatroban has been described for use in heparin-induced thrombocytopenia. The use of argatroban is briefly discussed, especially in the context of heparin resistance where anticoagulation can be challenging. Further research using argatroban in heparin resistant patients could be justified.
PDF
