Revised guideline on immunophenotyping in acute leukaemias and chronic lymphoproliferative disorders

Prevalence and clinical impact of CD56 and T-cell marker expression in acute myeloid leukaemia: A single-centre retrospective analysis

Flow cytometry-based immunophenotyping is a mainstay of diagnostics in acute myeloid leukaemia (AML). Aberrant CD56 and T-cell antigen expression is observed in a fraction subset of AML cases, but the clinical relevance remains incompletely understood. Here, we retrospectively investigated the association of CD56 and T-cell marker expression with disease-specific characteristics and outcome of 324 AML patients who received intensive induction therapy at our centre between 2011 and 2019. We found that CD2 expression was associated with abnormal non-complex karyotype, NPM1 wild-type status and TP53 mutation. CD2 also correlated with a lower complete remission (CR) rate (47.8% vs. 71.6%, p = 0.03). CyTdT and CD2 were associated with inferior 3-year event-free-survival (EFS) (5.3% vs. 33.5%, p = 0.003 and 17.4% vs. 33.1%, p = 0.02, respectively). CyTdT expression was also correlated with inferior relapse-free survival (27.3% vs. 48.8%, p = 0.04). In multivariable analyses CD2 positivity was an independent adverse factor for EFS (HR 1.72, p = 0.03). These results indicate a biological relevance of aberrant T-cell marker expression in AML and provide a rationale to further characterise the molecular origin in T-lineage-associated AML.

ROR1 expression in mature B lymphoid neoplasms by flow cytometry

Immunophenotyping by flow cytometry is an integral part of the diagnosis and classification of leukemias/lymphomas. The expression of ROR1 associated with chronic B lymphocytic leukemia (CLL) is well described in the literature, both in its diagnosis and in the follow-up of minimal residual disease (MRD) research, however, there are few studies regarding the expression pattern of ROR1 in other subtypes of mature B lymphoid neoplasms. With the aim of evaluating the expression of ROR1 and associating it with the expression of other important markers for the differentiation of mature B lymphoid neoplasms (MBLN), 767 samples of cases that entered our laboratory for immunophenotyping with clinical suspicion of MBLN were studied. ROR1 expression is predominant in CD5+/CD10- neoplasms. Overall, positive ROR1 expression was observed in 461 (60.1%) cases. The CD5+/CD10- group had a significantly higher proportion of ROR1 positive samples (89.9%) and more brightly expressed ROR1 than the other groups. Our results highlight the importance of evaluating ROR1 expression in the diagnosis of MBLN to contribute to the differential diagnosis, and possibly therapy of mainly CLL, and indicate that this marker could be considered as a useful addition to immunophenotypic panels, particularly for more challenging cases.

Role of Biomarkers in FLT3 AML

Simple Summary

Genetically heterogeneous disorder acute myeloid leukemia (AML) is marked by recurring mutations in FLT3. Current FLT3 inhibitors and other emerging inhibitors have helped in the improvement of the quality of standard of care therapies; however, the overall survival of the patients remains static. This is due to numerous mutations in FLT3, which causes resistance against these FLT3 inhibitors. For effective treatment of AML patients, alternative approaches are required to overcome this resistance. Here, we will summarize the biomarkers for FLT3 inhibitors in AML, as well as the alternative measures to overcome resistance to the current therapies.

Abstract

Acute myeloid leukemia is a disease characterized by uncontrolled proliferation of clonal myeloid blast cells that are incapable of maturation to leukocytes. AML is the most common leukemia in adults and remains a highly fatal disease with a five-year survival rate of 24%. More than 50% of AML patients have mutations in the FLT3 gene, rendering FLT3 an attractive target for small-molecule inhibition. Currently, there are several FLT3 inhibitors in the clinic, and others remain in clinical trials. However, these inhibitors face challenges due to lack of efficacy against several FLT3 mutants. Therefore, the identification of biomarkers is vital to stratify AML patients and target AML patient population with a particular FLT3 mutation. Additionally, there is an unmet need to identify alternative approaches to combat the resistance to FLT3 inhibitors. Here, we summarize the current knowledge on the utilization of diagnostic, prognostic, predictive, and pharmacodynamic biomarkers for FLT3-mutated AML. The resistance mechanisms to various FLT3 inhibitors and alternative approaches to combat this resistance are also discussed and presented.

Clinical implication and prognostic significance of FLT3-ITD and ASXL1 mutations in Egyptian AML patients: A single-center study

BACKGROUND

Both Fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) and Additional Sex Comb-like 1 (ASXL1) mutations are frequent and early genetic alteration events in acute myeloid leukemia (AML) patients. These genetic alterations may be associated with an unfavorable prognosis.

OBJECTIVE

Up to our knowledge, this is the first study performed to evaluate the clinical implication and prognostic significance of FLT3-ITD and ASXL1 mutations and their coexistence on the outcome of Egyptian AML patients.

METHODS

Our study included 83 patients with AML who were subjected to immunophenotyping and detection of FLT3-ITD and ASXL1 gene mutation by polymerase chain reaction (PCR) and real-time PCR, respectively.

RESULTS

FLT3-ITD and ASXL1 mutations were detected in 20.5% and 18.1% of AML patients respectively. Seven patients (8.4%) had co-expression of both genes' mutations. FLT3-ITD mutation was significantly higher in younger age, higher WBCs count and poor cytogenetic risk patients (P= 0.01, < 0.001 and 0.008 respectively). ASXL1 mutation was significantly higher in intermediate cytogenetic risk patients (P= 0.2). The mean period of survival and relapse-free survival (RFS) were significantly reduced in FLT3-ITD and ASXL1 mutations compared with their non-mutant types (P= 0.01 and 0.03 respectively). Both mutations were independent risk factors for overall survival (OS) and (RFS) in univariate and multivariate analysis in AML patients.

CONCLUSION

FLT3-ITD and ASXL1 gene mutations or their coexistence can predict a poor prognosis in AML patients.

CCR7 as a novel therapeutic target in t-cell PROLYMPHOCYTIC leukemia

T-cell prolymphocytic leukemia (T-PLL) is a poor prognostic disease with very limited options of efficient therapies. Most patients are refractory to chemotherapies and despite high response rates after alemtuzumab, virtually all patients relapse. Therefore, there is an unmet medical need for novel therapies in T-PLL. As the chemokine receptor CCR7 is a molecule expressed in a wide range of malignancies and relevant in many tumor processes, the present study addressed the biologic role of this receptor in T-PLL. Furthermore, we elucidated the mechanisms of action mediated by an anti-CCR7 monoclonal antibody (mAb) and evaluated whether its anti-tumor activity would warrant development towards clinical applications in T-PLL. Our results demonstrate that CCR7 is a prognostic biomarker for overall survival in T-PLL patients and a functional receptor involved in the migration, invasion, and survival of leukemic cells. Targeting CCR7 with a mAb inhibited ligand-mediated signaling pathways and induced tumor cell killing in primary samples. In addition, directing antibodies against CCR7 was highly effective in T-cell leukemia xenograft models. Together, these findings make CCR7 an attractive molecule for novel mAb-based therapeutic applications in T-PLL, a disease where recent drug screen efforts and studies addressing new compounds have focused on chemotherapy or small molecules.

Primary Nonanaplastic Peripheral Natural Killer/T-Cell Lymphoma in Pediatric Patients-An Unusual Distribution Pattern of Subtypes

Peripheral NK/T-cell lymphoma (PNKTCL) represents a group of uncommon diagnoses for children in Western countries, and studies have often necessitated multiple institutions to assemble enough cases. We retrospectively analyzed 11 cases of nonanaplastic PNKTCL in children over 19 years at our institution with comparison to several published large multi-institutional studies. Patients included 9 males and 2 females of white (5), Native American (3), and Hispanic (3) background with 6 cases of extranodal NK/T-cell lymphoma, nasal type (EN-NKTL, 54.6%), 3 cases of peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS, 27.2%), and 2 cases of systemic Epstein-Barr virus (EBV)-positive T-cell lymphoma of childhood (18.2%). Compared to the literature, our institution exceeded in frequency of total nonanaplastic PNKTCL (4.8% vs 0.9%-1.6%) with lesser relative incidence of PTCL-NOS (27.2% vs 42.9%-66.7%) and greater relative incidence of EN-NKTL (54.6% of cases vs 12.5%-47.6%), which significantly exceeded the literature's rate for Western institutions (13.5%). Potential influencing factors include population structure approximating those of non-Western countries with high EN-NKTL prevalence and the predisposition for EBV infection in this demography. These data suggest an uneven distribution of nonanaplastic PNKTCL in Western countries, and differential diagnoses may differ depending on practice location and associated patient population.

Comparison of Immunohistochemistry, Cytochemistry, and Flow Cytometry in AML for Myeloperoxidase Detection

Acute Myeloid Leukemia (AML) as per World Health Organization (WHO 2008) classification is on the basis of the antigenic characterization, enzymes restriction in the neoplastic myeloid cells and the specific translocations/mutations. AML can be assessed and differentiated by flowcytometry (FCM)/immunohistochemistry (IHC)/cytochemistry techniques. Myeloperoxidase (MPO) is an unequivocal marker to differentiate AML from the acute lymphoblastic leukemia. Despite FCM popularity, it has its limitations, in form of 'dry-tap', cost, and inability of being performed by retrospective analysis. IHC, though an old technique has overcome these disadvantages of FCM. Cytochemistry, on the other hand has its own advantages in being cost-effective; technically easy to do while its disadvantages are its inability to be carried out in the old samples, 'dry-tap' conditions in aleukemic leukemia. There has been non-uniformity in the literature among these techniques especially concerning their sensitivity for MPO. A prospective study was done at All India Institute of Medical Sciences New Delhi from 01 July 2014 to 30 Nov 2015 to include 120 diagnosed acute myeloid leukemia cases. Myeloperoxidase stain was done by cytochemistry, immunohistochemistry and flow cytometry and results were compared. There were 28 cases which showed discrepancies. Out of these 28 cases immunohistochemistry showed positivity in majority (22 cases) followed by flow cytometry (14 cases). Therefore it is important to employ more than one technique and IHC must be included for detection of MPO in all suspected cases of AML especially when negative with FCM .

Human myeloid inhibitory C-lectin: a highly specific and stable acute myeloid leukemia marker

The prognosis of acute myeloid leukemia (AML) is poor because of relapses occurring on conventional chemotherapy. The distinction between leukemic and normal stem cells relies on the expression of antigen combinations defining leukemia-associated immunophenotypes (LAIPs), which are absent or extremely infrequent in normal bone marrow. However, LAIPs are very different from patient to patient and are not necessarily stable over the course of the disease. Accordingly, we addressed the applicability of human myeloid inhibitory C-lectin (hMICL) by flow cytometry as a specific leukemic myeloid stem cell marker for the diagnosis of AML in CD34⁺ and CD34^- cases and evaluated the stability of hMICL during the course of the disease. hMICL expression was assessed in 78 bone marrow aspirate specimens obtained from AML patients at diagnosis (n = 40), complete remission (CR) (n = 28), and relapse (n = 10). AML patients at diagnosis were compared to 20 newly diagnosed acute lymphoblastic leukemia (ALL) patients and 20 healthy controls. hMICL was reevaluated in CR and relapse specimens. hMICL was expressed in 100% AML patients at diagnosis (mean ± standard deviation [SD], 60.3 ± 19.9%), both CD34⁺ and CD34^- , but not in ALL (mean ± SD, 3.3 ± 1.9%) or healthy controls (mean ± SD, 3.4 ± 2.6%) (P < .001). hMICL median fluorescence intensity ratio was higher in AML (mean ± SD, 15.9 ± 11.7) compared to ALL (mean ± SD, 4.5 ± 1.4) and healthy controls (mean ± SD, 4.4 ± 1.6) (P < .001). hMICL was expressed in all studied AML morphologic subtypes. Preserved stable expression of hMICL was found in CR and relapse specimens with no antigen loss. hMICL is a robust pan-AML-associated antigen with excellent diagnostic impact, extreme specificity to AML blasts, and stability throughout the course of the disease. hMICL could be incorporated into the routine flow cytometry setting within the initial diagnostic work-up and follow-up of AML.

Flowcytometric comparative analysis in acute leukemias between Indian and proposed minimal screening panel

BACKGROUND

Acute myeloid leukemia and acute lymphoid leukemia differ substantially in response to therapy and course, and accurate differentiation of the two is fundamental to therapeutic decisions. Immunophenotyping is used for this purpose, and various guidelines have been proposed regarding a minimal screening antibody panel. Most of them have been found inefficient.

METHODS

Eighty-two cases of consecutive acute leukemias reporting to this hospital over a period of two years were included in the study. Peripheral blood smear, bone marrow aspirate, and bone marrow biopsy were studied using morphology, cytochemical stains, and relevant immunohistochemical stains on selected biopsy specimens. Flowcytometry analysis was carried out using Indian consensus screening panel and our proposed minimal screening panel (PMSP) for comparison.

RESULT

Immunophenotyping using PMSP resulted in 95.12% accurate diagnosis versus Indian consensus minimal screening panel (ICMSP) with an accuracy of 92.68%. This result was statistically significant as per Chi Square tests.

CONCLUSION

PMSP can be used as a substitute for ICMSP, since it includes lineage-specific cytoplasmic antibodies, as well as lesser number of monoclonal antibodies, and enables us to diagnose mixed lineage leukemia. Fewer markers can be linked to a lower cost as well, which is relevant in a developing economy.

European canine lymphoma network consensus recommendations for reporting flow cytometry in canine hematopoietic neoplasms

BACKGROUND

Flow cytometry (FC) is assuming increasing importance in diagnosis in veterinary oncology. The European Canine Lymphoma Network (ECLN) is an international cooperation of different institutions working on canine lymphoma diagnosis and therapy. The ECLN panel of experts on FC has defined the issue of reporting FC on canine lymphoma and leukemia as their first hot topic, since a standardized report that includes all the important information is still lacking in veterinary medicine.

METHODS

The flow cytometry panel of the ECLN started a consensus initiative using the Delphi approach. Clinicians were considered the main target of FC reports. A panel of experts in FC was interrogated about the important information needed from a report.

RESULTS

Using the feedback from clinicians and subsequent discussion, a list of information to be included in the report was made, with four different levels of recommendation. The final report should include both a quantitative part and a qualitative or descriptive part with interpretation of the salient results. Other items discussed included the necessity of reporting data regarding the quality of samples, use of absolute numbers of positive cells, cutoff values, the intensity of fluorescence, and possible aberrant patterns of antigen expression useful from a clinical point of view.

CONCLUSION

The consensus initiative is a first step toward standardization of diagnostic approach to canine hematopoietic neoplasms among different institutions and countries. This harmonization will improve communication and patient care and also facilitate the multicenter studies necessary to further our knowledge of canine hematopoietic neoplasms. © 2016 International Clinical Cytometry Society.

Heterogeneity of Abnormal RUNX1 Leading to Clinicopathologic Variations in Childhood B-Lymphoblastic Leukemia

OBJECTIVES

Abnormalities of the RUNX1 gene in childhood B-acute lymphoblastic leukemia (B-ALL) are manifested by ETV6-RUNX1 or RUNX1 amplification. A detailed comparison between the two regarding clinicopathologic features with genetic analysis has not been performed previously. This parallel study assessed how different RUNX1 abnormalities affect the clinicopathology of B-ALL.

METHODS

We compared clinicopathologic factors, including age, sex, WBC count, cerebrospinal fluid (CSF) involvement, immunophenotype, and blast proliferation rate between B-ALL with RUNX1 amplification (10 cases) and B-ALL with ETV6-RUNX1 translocation (67 cases) in childhood B-ALL.

RESULTS

CD7 was often expressed in RUNX1 amplification but not in ETV6-RUNX1 (44% vs 0%, P = .0001) and appeared to correlate with CSF involvement in the former group (3/4 [75%]). CD13 was often detected in ETV6-RUNX1 with additional RUNX1 gain (38%) with an even higher frequency in double ETV6-RUNX1 translocation (77%), but was not detected in RUNX1 amplification (0%, P < .05). Children with RUNX1 amplification were older and more often CSF positive, while those with ETV6-RUNX1 were younger, more frequently had hyperleukocytosis, and had higher blast proliferation rates.

CONCLUSIONS

RUNX1 copy numbers seem to be proportional to the age of B-ALL onset and the frequency of CSF involvement, while RUNX1 amplification vs translocation causes aberrant expression of CD7 and CD13, respectively.

Minimal residual disease detection with tumor-specific CD160 correlates with event-free survival in chronic lymphocytic leukemia

In chronic lymphocytic leukemia (CLL), the detection of minimal residual disease (MRD) correlates with outcome in the trial setting. However, MRD assessment does not guide routine clinical management and its assessment remains complex. We incorporated detection of the B cell, tumor-specific antigen CD160 to develop a single-tube, flow cytometry assay (CD160FCA) for CLL MRD to a threshold of 10⁻⁴ to 10⁻⁵. One hundred and eighty-seven patients treated for CLL were enrolled. Utilizing the CD160FCA methodology, there was a high level of comparison between blood and bone marrow (R=0.87, P<0.001). In a validation cohort, CD160FCA and the international standardised approach of the European Research Initiative on CLL group demonstrated high concordance (R=0.91, P<0.01). Patients in complete remission (CR) and CD160FCA negative had longer event-free survival (EFS) (63 vs 16 months, P<0.01) and prolonged time to next treatment (60 vs 15 months, P<0.001) vs MRD positive patients; with a median time to MRD positivity of 36 months. In multivariate analysis, CD160FCA MRD detection was independently predictive of EFS in patients in CR and even predicted EFS in the good-risk cytogenetic subgroup. CD160FCA offers a simple assay for MRD detection in CLL and gives prognostic information across different CLL risk groups.

Can threshold for MPO by flow cytometry be reduced in classifying acute leukaemia? A comparison of flow cytometric and cytochemical myeloperoxidase using different flow cytometric cut-offs

Objectives Myeloperoxidase (MPO) detection either by enzyme cytochemistry (cMPO) or flow cytometry (fMPO) plays a major role in acute leukaemia (AL) diagnosis as per World Health Organization (WHO) 2008 classification. Although 3% cMPO was recommended as positivity, no specific cut-off had been mentioned by WHO for fMPO. Various authors recommend different cut-offs ranging from 3 to 28% for fMPO. The aim of this study was to analyse fMPO cut-offs ranging from 3 to 10% in classifying AL and to assess whether a new cut-off could be suggested. Methods Totally, 216 cases of AL were retrospectively analysed for fMPO ranging from 3 to 10% and compared with gold standard. Presence of cMPO (≥3%) and/or expression of two or more pan-myeloid markers (CD13, CD33, and CD117) in the absence of CD19 and CD3 were kept as gold standard for diagnosis of acute myeloid leukaemia (AML). Results Sensitivities for classifying AL as AML/mixed phenotypic acute leukaemia (MPAL) at 3, 5.4, and 10% were 98.3, 98.3, and 96.6%, respectively, whereas specificities at this cut-off were 22.2, 91, and 71%, respectively. Discussion Only few studies have been done in this aspect to define a consistent cut-off for fMPO for proper classification of acute leukaemias. This was one of the largest and few studies available till date in this regard. Conclusion The newer cut-off for fMPO (5.4%) emerged out from our study with best sensitivity and specificity for accurately classifying AL cases into acute lymphoblastic leukaemia, AML, and MPAL.

Developments in the immunophenotypic analysis of haematological malignancies

Immunophenotyping is the method by which antibodies are used to detect cellular antigens in clinical samples. Although the major role is in the diagnosis and classification of haematological malignancies, applications have expanded over the past decade. Immunophenotyping is now used extensively for disease staging and monitoring, to detect surrogate markers of genetic aberrations, to identify potential immuno-therapeutic targets and to aid prognostic prediction. This expansion in applications has resulted from developments in antibodies, methodology, automation and data handling. In this review we describe recent advances in both the technology and applications for the analysis of haematological malignancies. We highlight the importance of the expanding repertoire of testing capability for diagnostic, prognostic and therapeutic applications. The impact and significance of immunophenotyping in the assessment of haematological neoplasms are evident.

Gravin gene expression in acute myeloid leukemia

Acute leukemias are caused by genetic and epigenetic mechanisms involving tumor suppressor genes and oncogenes. Aberrant DNA methylation patterns are the most frequent molecular alterations detected in acute myeloid leukemia (AML). Gravin is down-regulated in several solid tumors and is implicated in tumorigenesis. To explore its role in the molecular pathogenesis and its possible prognostic importance in AML, we have evaluated the expression levels of the gravin gene in 83 acute myeloid leukemia patients as compared with controls using quantitative real-time polymerase chain reaction (qRT-PCR). Mean gravin expression was 0.53 ± 1.34 and 8.81 ± 11.6 for patients and controls, respectively, and was found to be about 16-fold lower than controls. Gravin gene expression was lower than controls in 83.1 % (69/83) and was similar to controls in 16.9 % (14/83) of cases (p < 0.0001). It was found that there was no significant correlation between gravin expression and laboratory prognostic markers (p > 0.05). Gravin expression was highest in complete remission (1.065 ± 1.79) and lowest in relapse (0.019 ± 0.03) with a statistical difference (p = 0.004). Patients with gravin expression below median level had higher risk to develop relapse (OR = 8.689, 95 % CI = 2.464-30.638; p < 0.0001). No statistical correlation was reported between gravin expression and survival times (OS, DFS) (p = 0.482, 0.409, respectively), and this was confirmed in multivariate analysis. Gravin gene expression was found to be decreased in acute myeloid leukemia, and the degree of its decreased expression has been found to be correlated with poor prognosis.

Technologies supporting analytical cytology: clinical, research and drug discovery applications

The tools and techniques developed for analytical cytology have become invaluable in expanding the development of cancer screening programs and biomarker discovery for personalized medicine. Detecting cellular, molecular, and functional changes of diseased tissue as defined by quantitative analytical methodologies has enhanced the field of medical diagnostics and prognostics. The focus of this review is to outline applications and recent technical advances in flow cytometry, laser scanning cytometry, image cytometry, and quantitative image analysis, as they pertain to clinical, research, and drug discovery applications.

Flow cytometry in clinical pathology

Flow cytometry has had an impact upon all areas of clinical pathology and now, in the 21st century, it is truly coming of age. This study reviews the application of flow cytometry within clinical pathology with an emphasis upon haematology and immunology. The basic principles of flow cytometry are discussed, including the principles and considerations of the flow-cell and hydrodynamic focusing, detector layout and function, use of fluorochromes and multicolour flow cytometry (spectral overlap and colour compensation), alongside the strategies available for sample preparation, data acquisition and analysis, reporting of results, internal quality control, external quality assessment and flow sorting. The practice of flow cytometry is discussed, including the principles and pitfalls associated with leukocyte immunophenotyping for leukaemia and lymphoma diagnosis, immune deficiency, predicting and monitoring response to monoclonal antibody therapy, rare event detection and screening for genetic disease. Each section is illustrated with a case study. Future directions are also discussed.

Application of flow cytometry in pediatric hematology-oncology

Applications of flow cytometry in pediatric cancers have expanded substantially in recent years. In acute leukemias, the commonest childhood cancer, flow cytometry can now define complex antigenic profiles that are associated with specific cytogenetic/molecular defects and can also directly identify BCR-ABL fusion protein. Flow cytometry based scoring system has been described for diagnosis of myelodysplastic syndromes. In solid tumors, flow cytometry was previously used mainly to determine DNA content for prognosis; however, recent studies in children with neuroblastoma and Ewing sarcoma have identified its diagnostic utility. In this review, we will discuss the current and future applications of flow cytometry in pediatric hematology-oncology.

Clinical pathological and epidemiological assessment of morphologically and immunologically confirmed canine leukaemia

Traditionally, classification of leukaemia in dogs has relied on morphological examination and cytochemical staining patterns, but aberrant cellular morphology and stain uptake often curtails accurate categorization, and historical data based on this classification may be unreliable. Immunophenotyping is now the gold standard for classification of leukaemias. The purpose of this prospective study was to assess the clinical pathological and epidemiological features of a population of dogs with morphologically and immunologically confirmed leukaemia and to compare them within categories: acute and chronic lymphoid leukaemia (ALL and CLL), and acute and chronic myeloid leukaemia (AML and CML). There were 64 cases of morphologically and immunologically confirmed leukaemia: 25 cases of ALL, 17 cases of CLL and 22 cases of AML. Prevalence of B and T immunophenotypes in ALL and CLL was not statistically different. Dogs with AML were significantly younger than those with ALL at presentation (P = 0.04). Golden Retriever dogs in the study population were overrepresented in comparison with a control population of dogs (6/25 ALL cases, 8/64 leukaemia cases). No sex was overrepresented. Dogs with ALL had significantly more severe neutropenia (P = 0.001) and thrombocytopenia (P = 0.002) than those with CLL and had significantly more cytopenias. The severity and numbers of cytopenias seen in ALL and AML were not significantly different. Twenty-one of the leukaemia cases showed one cytopenia, fourteen had two cytopenias and twenty-one cases had pancytopenia. Anaemia was the most common cytopenia seen in isolation (17/21). No dogs had neutropenia without anaemia and/or thrombocytopenia. Total white blood cell counts were not different between the groups. The atypical cell counts within the peripheral blood were significantly higher in ALL than AML; both in isolation and as a percentage of the total white blood cell count (P = 0.03). This study strengthens the hypothesis that acute leukaemias give rise to more profound cytopenias, affecting more cell lines, than chronic leukaemias.

Guidelines for an integrated diagnostic approach of chronic lymphoproliferative disorders in the routine laboratory of haematology in Belgium

This paper summarizes the minimal workout of chronic lymphoproliferative disorders in a routine laboratory of haematology as recommended by a team of experienced laboratory supervisors in Belgium, taking into account the specific organisation of healthcare in Belgium, the innovations in the field of molecular analyses and related reimbursement. The starting point was essentially based upon clinical and/or haematological indications and it is emphasized that conclusions should be drawn in close dialogue with the clinician and experts in cytogenetics and histopathology. Reports made in the laboratory should be based upon an integration of cytomorphological, immunophenotypical and molecular data. These guidelines are not intended to be used as universal 'diagnostic pathways', but should be useful in developing local diagnostic pathways. It is well understood that this consensus, being valid anno 2009, may rapidly change with new technologies being introduced and new targets discovered.

Acute Panmyelosis with Myelofibrosis: Clinical, Immunophenotypic and Cytogenetic Study of Twelve Cases

The clinical, cytogenetic, and immunophenotypic features in 12 adult patients with acute panmyelosis with myelofibrosis (APMF; ICD-0-3: 9931/3; C42.1) are reported (median age: 57 years; f/m = 1.4). The white cell count (WBC) was normal in 3 patients; 9 had leucopenia. The median hemoglobin value was 64.5 g/l, and median platelet count 12 x 10(9)/l. Bone marrow biopsy showed a hypercellular marrow in 10/12 patients with a significant infiltration of pathological blasts (range: 30 - 60%). All the cases had marked reticulin fibrosis. Immunophenotyping of bone marrow blast cells showed the expression of early (CD34) and lineage-unspecified antigens (HLA-DR) in 6/7, and 7/7 patients, respectively. "Early" myeloid antigens (CD13, CD33) were seen in 6/7 and 4/6 patients respectively. Monocyte antigen (CD14) was expressed in 3/7 patients. Megakaryocyte antigen (CD61) and erythroid cell antigen (GpA) were each expressed in only 1 patient. Two patients had expression of CD34, HLA-DR and "early" myeloid antigens by their bone marrow blast cells and 1 of these also had a co-expression of the antigens from a differentiated monocytic cell proliferation (lysozyme+, CD68+). Nonspecific chromosomal aberrations were recorded in 8/10 patients. The median survival was 2 months. These findings suggest an immature myeloid phenotype of blast cells in APMF. In 6/9 patients a leukemic cell differentiation into monocytic, megakaryocytic or erythroid lineage was also demonstrated.

Expression of CD133 on leukemia-initiating cells in childhood ALL

Optimization of therapy for childhood acute lymphoblastic leukemia (ALL) requires a greater understanding of the cells that proliferate to maintain this malignancy because a significant number of cases relapse, resulting from failure to eradicate the disease. Putative ALL stem cells may be resistant to therapy and subsequent relapses may arise from these cells. We investigated expression of CD133, CD19, and CD38 in pediatric B-ALL. Cytogenetic and molecular analyses demonstrated that karyotypically aberrant cells were present in both CD133+/CD19+ and CD133+/CD19− subfractions, as were most of the antigen receptor gene rearrangements. However, ALL cells capable of long-term proliferation in vitro and in vivo were derived from the CD133+/CD19− subfraction. Moreover, these CD133+/CD19− cells could self-renew to engraft serial nonobese diabetic–severe combined immunodeficient recipients and differentiate in vivo to produce leukemias with similar immunophenotypes and karyotypes to the diagnostic samples. Furthermore, these CD133+/CD19− ALL cells were more resistant to treatment with dexamethasone and vincristine, key components in childhood ALL therapy, than the bulk leukemia population. Similar results were obtained using cells sorted for CD133 and CD38, with only the CD133+/CD38− subfraction demonstrating xenograft repopulating capacity. These data suggest that leukemia-initiating cells in childhood B-ALL have a primitive CD133+/CD19− and CD38− phenotype.

The role of multiparameter flow cytometry for detection of minimal residual disease in acute myeloid leukemia

The presence of minimal residual disease (MRD) in the bone marrow (BM) of patients with acute myeloid leukemia (AML) following chemotherapy has been established by many studies to be strongly associated with relapse of leukemia. In addition, detection of MRD is the major objective of many of the newer diagnostic techniques used in malignant hematology. Because of the wide availability and conceptual straightforwardness of immunophenotyping, flow cytometry is the most accessible method for MRD detection. This review is not an overview of all MRD studies, but rather discusses the possibilities for optimizing MRD detection, the use of multiparameter flow cytometry (MFC) techniques in MRD detection, and the implications for future patient treatment. This review focuses on MRD detection in AML using MFC and discusses the reported correlations of MRD, clinical and biologic features of the disease, and outcome. In addition, it discusses the laboratory and clinical aspects of this approach.

Acute leukemia of ambiguous lineage, biphenotype, without CD34, TdT or TCR-rearrangement

Biphenotypic acute leukemia (BAL) is a rare entity that comprises 0.5-3% of all acute leukemias and probably arises from multipotent progenitor cells. The optimal approach for BAL therapy is unknown. Thus, it is important to elucidate the origin of the neoplastic cells for determination of the appropriate therapy. We report the case of a 41-year-old man with BAL having myeloid and T-lymphoid lineage phenotypes. Strangely, neither CD34 nor TdT expression nor rearrangement of TCR-alpha/beta, delta/gamma genes were shown. This pattern is rarely encountered and suggests that the blast cells were possibly considered immature with aspects of differentiation indicating myeloid lineage, rather than T-lymphoid lineage.

Immunohistochemistry is a more sensitive marker for the detection of myeloperoxidase in acute myeloid leukemia compared with flow cytometry and cytochemistry

Myeloperoxidase (MPO) is an unequivocal marker of myeloid differentiation which is routinely detected using cytochemistry (CC), flow cytometry (FC) and immunohistochemistry (IH). Several studies have compared the use of two of these methods, but to our knowledge none has compared all three techniques. We compared the performance of these three modalities in the detection of MPO in 158 cases of acute myeloid leukaemia (AML). Discrepancies were noted in a total of 28 cases. Of 110 cases in which all three modalities were performed, 23 cases showed discrepancies. CC was the least sensitive marker, being negative in 11 of 23 cases in the presence of positive IH and/or FC. IH was the most sensitive marker with only one case being negative in the presence of a positive result by FC and/or CC. The results highlight the necessity of employing more than one method in determining the presence of MPO and confirm the important role of IH in the diagnosis of AML particularly in cases where MPO is not detected by CC and FC.

Clinical management of primary non-acute promyelocytic leukemia acute myeloid leukemia: Practice Guidelines by the Italian Society of Hematology, the Italian Society of Experimental Hematology, and the Italian Group for Bone Marrow Transplantation

As many options are now available to treat patients with de novo acute myeloid leukemia, the Italian Society of Hematology and two affiliated societies (SIES and GITMO) commissioned project to an Expert Panel aimed at developing clinical practice guidelines for acute myeloid leukemia treatment. After systematic comprehensive literature review, the Expert Panel formulated recommendations for the management of primary acute myeloid leukemia (with the exception of acute promyelocytic leukemia) and graded them according to the supporting evidence. When evidence was lacking, consensus-based statements have been added. First-line therapy for all newly diagnosed patients eligible for intensive treatment should include one cycle of induction with standard dose cytarabine and an anthracycline. After achieving complete remission, patients aged less than 60 years should receive consolidation therapy including high-dose cytarabine. Myeloablative allogeneic stem cell transplantation from an HLA-compatible sibling should be performed in first complete remission: 1) in children with intermediate-high risk cytogenetics or who achieved first complete remission after the second course of therapy; 2) in adults less than 40 years with an intermediate-risk; in those aged less than 55 years with either high-risk cytogenetics or who achieved first complete remission after the second course of therapy. Stem cell transplantation from an unrelated donor is recommended to be performed in first complete remission in adults 30 years old or younger, and in children with very high-risk disease lacking a sibling donor. Alternative donor stem cell transplantation is an option in high-risk patients without a matched donor who urgently need transplantation. Patients aged less than 60 years, who either are not candidate for allogeneic stem cell transplantation or lack a donor, are candidates for autologous stem cell transplantation. We describe the results of a systematic literature review and an explicit approach to consensus techniques, which resulted in recommendations for the management of primary non-APL acute myeloid leukemia.

CD49d expression in chronic lymphocytic leukemia: a prognostic parameter and a therapeutic target

Evaluation of: Shanafelt TD, Geyer SM, Bone ND et al.: CD49d expression is an independent predictor of overall survival in patients with chronic lymphocytic leukaemia: a prognostic parameter with therapeutic potential. Br. J. Haematol. 140(5), 537–546 (2008). Chronic lymphocytic leukemia is a progressive disease for which there is no curative chemotherapy regimen. Progression may be either a late or an early event, occurring after more than 15 years or within 5 years from diagnosis. Counseling and management should be personalized on individual risk of progression, usually assessed by clinical staging and by investigating the presence of well-established biological markers: mutational status of immunoglobulin heavy variable region (IGHV) genes, chromososomal alterations as detected by fluorescence in situ hybridization, and expression of ZAP-70 and CD38. Several additional factors have been so far proposed as putative prognosticators, with the aim to find more reliable and easily measurable markers. Two recent studies indicate that CD49d is an independent prognosticator for overall survival and time-to-treatment, and that its value may be even more powerful than ZAP-70, CD38 or IGHV mutational status. CD49d is easily measurable by simple flow cytometer testing and is a potential therapeutic target, thanks to the availability of natalizumab, a US FDA-approved humanized monoclonal antibody for treatment of multiple sclerosis and Crohn’s disease.

Flow cytometric lymphocyte subset enumeration: 10 years of external quality assessment in the Benelux countries

A biannual external quality assessment (EQA) scheme for flow cytometric lymphocyte immunophenotyping is operational in the Benelux countries since 1996. We studied the effects of the methods used on assay outcome, and whether or not this EQA exercise was effective in reducing between-laboratory variation. Eighty test samples were distributed in 20 biannual send-outs. Per send-out, 50-71 participants were requested to enumerate CD3+, CD4+, and CD8+ T cells, B cells, and NK cells, and to provide methodological details. Participants received written debriefings with personalized recommendations after each send-out. For this report, data were analyzed using robust multivariate regression. Five variables were associated with significant positive or negative bias of absolute lymphocyte subset counts: (i) platform methodology (i.e., single-platform assays yielded lower CD4+ and CD8+ T-cell counts than did dual-platform assays); (ii) sample preparation technique (i.e., assays based on mononuclear cells isolation yielded lower T-cell counts than those based on red cell lysis); (iii) gating strategies based on CD45 and sideward scatter gating of lymphocytes yielded higher CD4+ T-cell counts than those based on "backgating" of lymphocytes guided by CD45 and CD14); (iv) stabilized samples were generally associated with higher lymphocyte subset counts than nonstabilized samples; and (v) laboratory. Platform methodology, sample stabilization, and laboratory also affected assay variability. With time, assay variability tended to decline; this trend was significant for B-cell counts only. In addition, significant bias and variability of results, independent of the variables tested for in this analysis, were also associated with individual laboratories. In spite of our recommendations, participants tended to standardize their techniques mainly with respect to sample preparation and gating strategies, but less with absolute counting techniques. Failure to fully standardize protocols may have led to only modest reductions in variability of results between laboratories.

Haematology

This article examines some of the recent advances in haematology in both the malignant and non-malignant areas of the speciality. Improvements in survival rates after effective chemotherapy now present the haematologist with the challenges of how to minimise therapeutic side effects without affecting outcome and the role of stratification as well as specific monitoring of enzyme activity are discussed. Many treatments for haematological malignancy have significant late effects which are only now becoming a problem--what these are, how to identify them and how they can be limited are examined. The increased knowledge of the altered pathways that lead to malignancy has allowed a whole slew of new therapies to be developed often with excellent results. The role of new iron chelation agents and the so called 'universal haemostatic agent' activated factor VII are also discussed.

Characterization of a progenitor cell population in childhood T-cell acute lymphoblastic leukemia

A significant proportion of children with T-cell acute lymphoblastic leukemia (T-ALL) continue to fail therapy. Consequently, characterization of the cells that proliferate to maintain the disease should provide valuable information on the most relevant therapeutic targets. We have used in vitro suspension culture (SC) and nonobese diabetic-severe combined immune deficient (NOD/SCID) mouse assays to phenotypically characterize and purify T-ALL progenitor cells. Cells from 13 pediatric cases were maintained in vitro for at least 4 weeks and expanded in 8 cases. To characterize the progenitors, cells were sorted for expression of CD34 and CD4 or CD7 and the subfractions were evaluated in vitro and in vivo. The majority of cells capable of long-term proliferation in vitro were derived from the CD34+/CD4- and CD34+/CD7- subfractions. Moreover, the CD34+/CD4- or CD7- cells were the only subfractions capable of NOD/SCID engraftment. These T-ALL cells successfully repopulated secondary and tertiary recipients with equivalent levels of engraftment, demonstrating self-renewal ability. The immunophenotype and genotype of the original leukemia cells were preserved with serial passage in the NOD/SCID mice. These data demonstrate the long-term repopulating ability of the CD34+/CD4- and CD34+/CD7- subfractions in T-ALL and suggest that a cell with a more primitive phenotype was the target for leukemic transformation in these cases.

Cytogenetics, molecular and ultrastructural characteristics of biphenotypic acute leukemia identified by the EGIL scoring system

Biphenotypic acute leukemia (BAL) is a rare, difficult to diagnose entity. Its identification is important for risk stratification in acute leukemia (AL). The scoring proposal of the European Group for the Classification of Acute Leukemia (EGIL) is useful for this purpose, but its performance against objective benchmarks is unclear. Using the EGIL system, we identified 23 (3.4%) BAL from among 676 newly diagnosed AL patients. Mixed, small and large blast cells predominated, with FAB M2 and L1 constituting the majority. All patients were positive for myeloid (M) markers and either B cell (B) (17 or 74%) or T cell (T) (8 or 34%) markers with two exceptional patients demonstrating trilineage phenotype. Six (50%) of studied M-B cases were positive for both IGH and TCR. In six (26%) patients myeloid lineage commitment was also demonstrable by electron cytochemistry. Abnormal findings were present in 19 (83%) patients by cytogenetics/FISH/molecular analysis as follows: t(9;22) (17%); MLL gene rearrangement (26%); deletion(6q) (13%); 12p11.2 (9%); numerical abnormalities (13%), and three (13%) new, previously unreported translocations t(X;6)(p22.3;q21); t(2;6)(q37;p21.3); and t(8;14)(p21;q32). In conclusion, the EGIL criteria for BAL appear robust when compared against molecular techniques that, if applied routinely, could aid in detecting BAL and help in risk stratification.

A young male with bone pain

A 38-year-old male presented with a 6-month history of pain in the right thigh associated with weight loss. His full blood count was normal, as were his biochemistry, immunology, autoimmune screen and prostate-specific antigen. Inflammatory markers were elevated. All preliminary radiological investigations were normal. Bone scan and magnetic resonance imaging were highly suggestive of a leukaemic process. Bone marrow biopsy and peripheral blood film confirmed the diagnosis of an acute biphenotypic leukaemia. This case report highlights the fact that bone pain associated with a normal peripheral blood count may be the presentation of an acute haematological disorder in both adults and children.

Acute lymphoblastic leukemia with the phenotype of a putative B-cell/T-cell bipotential precursor

Biphenotypic acute leukemias (BALs) are uncommon. Most are of myeloid-B-cell or myeloid-T-cell lineage. We report herein a 70-year-old man with an unusual acute leukemia where the blasts expressed both B- and T-lymphoid markers. He presented to us with an enlarging cutaneous tumor. The presenting peripheral blood and bone marrow aspirate showed 40% and 90% blasts, respectively, which were negative for the usual cytochemical stains. The flow cytometric analysis revealed that the blasts were positive for CD19, CD20, CD22, cytoplasmic (Cyt) CD79a, CD10, Cyt CD3, CD5, CD7, CD4, HLA-DR, TdT, and were negative for myeloid markers. According to the scoring system from the European Group for the Immunological Characterization of Acute Leukaemias (EGIL), this case was an unequivocal B-cell/T-cell BAL. Conventional cytogenetic analysis revealed 46XY [t(4;11)(q31;q13), add(8)(q24), der(9)del(9)(p21)del(9)(q32q34), -13, +mar] in all 25 metaphases analyzed. Fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) for 11q23 rearrangements as well as t(9;22) were negative. PCR for both TCR-gamma and IgH gene analyses revealed polyclonal rearrangements. We postulate that this case of BAL might have arisen from the putative common lymphoid progenitor cell.

Rapid diagnosis and characterization of acute promyelocytic leukaemia in routine laboratory practice

The rapid diagnosis of the t(15;17)(q22;q21) promyelocytic leukaemia is important in the early introduction of targeted therapy with all-trans retinoic acid plus chemotherapy. It has been noted that these are usually myeloperoxidase (MPO)-positive and HLA-DR-negative with homogenous expression of CD33 and heterogeneous expression of CD13. We evaluated the use of immunophenotyping, morphology and cytogenetics in our own practice. Cascade testing, using cytoplasmic MPO expression in a high percentage of blast cells in bone marrow as the primary screen and PML (promyelocytic leukaemia protein) expression as the secondary confirmatory test, allowed rapid identification of the cases with t(15;17). This approach allows early instigation of appropriate therapy.

Diagnosis of plasma cell leukaemia: findings of the UK NEQAS for Leucocyte Immunophenotyping scheme

The diagnosis of plasma cell leukaemia, a rare disorder with an aggressive clinical course and poor prognosis, is not always straightforward and may be dependent on the results of immunophenotyping. Samples from two cases of plasma cell leukaemia have been issued by the UK NEQAS for Leucocyte Immunophenotyping Scheme during the last 5 years and on each occasion a significant number of laboratories failed to make the correct diagnosis. The details of the two samples issued and the results of both surveys are presented. The data highlights the need to adhere to guidelines for immunophenotyping, with respect to using the correct antibody panels, the importance of data interpretation in conjunction with morphological appearance as well as the need to participate in external quality assurance schemes.