CD56 antigenic expression in acute myeloid leukemia identifies patients with poor clinical prognosis

Unraveling genotype-phenotype associations and predictive modeling of outcome in acute myeloid leukemia

Acute myeloid leukemia (AML) comprises 32% of adult leukemia cases, with a 5-year survival rate of only 20-30%. Here, the immunophenotypic landscape of this heterogeneous malignancy is explored in a single-center cohort using a novel quantitative computational pipeline. For 122 patients who underwent induction treatment with intensive chemotherapy, leukemic cells were identified at diagnosis, computationally preprocessed, and quantitatively subtyped. Computational analysis provided a broad characterization of inter- and intra-patient heterogeneity, which would have been harder to achieve with manual bivariate gating. Statistical testing discovered associations between CD34, CD117, and HLA-DR expression patterns and genetic abnormalities. We found the presence of CD34+ cell populations at diagnosis to be associated with a shorter time to relapse. Moreover, CD34- CD117+ cell populations were associated with a longer time to AML-related mortality. Machine learning (ML) models were developed to predict 2-year survival, European LeukemiaNet (ELN) risk category, and inv(16) or NPM1mut, based on computationally quantified leukemic cell populations and limited clinical data, both readily available at diagnosis. We used explainable artificial intelligence (AI) to identify the key clinical characteristics and leukemic cell populations important for our ML models when making these predictions. Our findings highlight the importance of developing objective computational pipelines integrating immunophenotypic and genetic information in the risk stratification of AML.

Clinical, immunophenotypic, and genomic findings of acute myeloid leukemia with RAM immunophenotype: Comparison with other CD56-positive acute leukemias

Background

Acute myeloid leukemia (AML) with RAM immunophenotype is a newly recognized high-risk AML immunophenotypic subcategory characterized by blasts with bright expression of CD56 and weak to absent expression of CD45, HLA-DR, and CD38, as first described by the Children's Oncology Group (COG). The relationship between AML-RAM and other CD56-positive acute leukemias is unclear. The goal of this study is to characterize the clinicopathological characteristics of AML with RAM phenotype and compare them with other CD56 co-expressing acute leukemias.

Methods

From a multi-institutional search, we identified a total of 160 CD56+ acute leukemia cases, including AML-RAM (n = 28), CD56+ acute undifferentiated leukemia (AUL) (n = 11), CD56+ T-lymphoblastic leukemia (n = 39), and CD56+ AML (n = 81). We compared the clinical and pathologic findings of these groups.

Results

AML-RAM patients were significantly younger and presented with significantly higher platelet and white blood cell counts and bone marrow (BM) blast percentages when compared to AUL (p > 0.05) and had higher median BM blast percentages than T-ALL and CD56+ AML groups (both p < 0.05). Flow cytometry showed significantly brighter expression of CD56 on blasts as compared to other CD56+ AML cases, partial CD34 expression compared to AUL, and AML, weak-to-absent CD38 expression compared to all groups, and absent HLA-DR and terminal deoxynucleotidyl transferase as compared to AUL and T-ALL (all p < 0.05). The frequency of abnormal karyotypes was significantly higher among RAM when compared to all groups (p < 0.05). Next-generation sequencing profiles differed among the leukemia groups, with significant enrichment of CBFA2T3::GLIS2 fusions (p < 0.05) and TP53 mutations (p < 0.05) in RAM cases compared to other AML control groups, and U2AF1 (p < 0.05), serine and arginine-rich splicing factor 2 (p < 0.05), and BCL6 co-repressor (p < 0.05) mutations compared to AUL. Clinical outcome analysis demonstrated significantly lower 3-year overall survival of the RAM subgroup (36 months) compared to control groups (p = 0.002).

Conclusion

We find that AML with RAM phenotype occurs primarily in younger ages, with distinct clinicopathological, immunophenotypic, and mutational presentations, and worse prognosis. This diagnosis should be considered in the clinical differential diagnosis of CD56-positive acute leukemias.

A differential diagnosis method for systemic CAEBV and the prospect of EBV-related immune cell markers via flow cytometry

Chronic active Epstein-Barr virus (CAEBV) infection of the T-cell or Natural killer (NK)-cell type, systemic form (systemic CAEBV or sCAEBV) was defined by the WHO in 2017 as an EBV-related lymphoproliferative disorder and is listed as an EBV-positive T-cell and NK-cell proliferation. The clinical manifestations and prognoses are heterogeneous. This makes systemic CAEBV indistinguishable from other EBV-positive T-cell and NK-cell proliferations. Early diagnosis of systemic CAEBV and early hematopoietic stem cell transplantation can improve patient prognosis. At present, the diagnosis of systemic CAEBV relies mainly on age, clinical manifestations, and cell lineage, incurring missed diagnosis, misdiagnosis, long diagnosis time, and inability to identify high-risk systemic CAEBV early. The diagnostic methods for systemic CAEBV are complicated and lack systematic description. The recent development of diagnostic procedures, including molecular biological and immunological techniques such as flow cytometry, has provided us with the ability to better understand the proliferation of other EBV-positive T cells and NK cells, but there is no definitive review of their value in diagnosing systemic CAEBV. This article summarizes the recent progress in systemic CAEBV differential diagnosis and the prospects of flow cytometry.

Immunophenotype of myeloid granulocytes in Chinese patients with BCR::ABL1-negative myeloproliferative neoplasms

Typical BCR::ABL1-negative myeloproliferative neoplasms (MPN) are mainly referred to as polycythemia vera (PV), essential thrombocythemia (ET), and primary myelofbrosis (PMF). Granulocytes in MPN patients are involved in their inflammation and form an important part of the pathophysiology of MPN patients. It has been shown that the immunophenotype of granulocytes in MPN patients is altered. We used flow cytometry to explore the immunophenotype of MPN patients and correlate it with clinical parameters. The results showed that PMF patients and PV patients had higher CD15+CD11b+ granulocytes than ET patients and normal controls. When grouped by gene mutation, changes in the granulocyte immunophenotype of MPN patients were independent of the JAK2V617F and CALR mutations. There was no significant heterogeneity in immunophenotype between ET patients and Pre-PMF, and between Overt-PMF and Pre-PMF patients. Granulocytes from some MPN patients showed an abnormal CD13/CD16 phenotype with a significant increase in mature granulocytes on molecular and cytomorphological grounds, and this abnormal pattern occurred significantly more frequently in PMF patients than in ET patients. CD15-CD11b- was negatively correlated with WBC and Hb and positively correlated with DIPSS score, whereas high CD10+ granulocytes were significantly and negatively associated with prognostic system IPSS and DIPSS scores in PMF patients. In conclusion, this study demonstrates the landscape of bone marrow granulocyte immunophenotypes in MPN patients. MPN patients, especially those with PMF, have a significant granulocyte developmental overmaturation phenotype. CD10+ granulocytes may be involved in the prognosis of PMF patients.

A blastic plasmacytoid dendritic cell neoplasm-like immunophenotype is negatively associated with CEBPA bZIP mutation and predicts unfavorable prognosis in acute myeloid leukemia

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive myeloid malignancy which characteristically expresses an atypical phenotype including CD123+, CD56+, and CD4+. We are aimed to investigate the clinical and prognostic characteristics of AML patients exhibiting BPDCN-like immunophenotype and provide additional insights for risk stratification of AML. A total of 241 newly diagnosed AML patients were enrolled in this retrospective study and categorized into BPDCN-like positive (n = 125)/negative (n = 116) groups, determined by the present with CD123+ along with either CD56+ or CD4+, or both. Subsequently, an analysis was conducted to examine the general clinical characteristics, genetic profiles, and prognosis of the two respective groups. Patients with BPDCN-like immunophenotype manifested higher frequencies of acute myelomonocytic leukemia and acute monoblastic leukemia. Surprisingly, the presence of the BPDCN-like immunophenotype exhibited an inverse relationship with CEBPA bZIP mutation. Notably, patients with BPDCN-like phenotype had both worse OS and EFS compared to those without BPDCN-like phenotype. In the CN-AML subgroups, the BPDCN-like phenotype was associated with worse EFS. Similarly, a statistically significant disparity was observed in both OS and EFS within the favorable-risk subgroup, while only OS was significant within the adverse-risk subgrouMoreover, patients possessing favorable-risk genetics without BPDCN-like phenotype had the longest survival, whereas those who had both adverse-risk genetics and BPDCN-like phenotype exhibited the worst survival. Our study indicated that BPDCN-like phenotype negatively associated with CEBPA bZIP mutation and revealed a significantly poor prognosis in AML. Moreover, the 2022 ELN classification, in combination with the BPDCN-like phenotype, may better distinguish between different risk groups.

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.

Prognostic Impact of Unsupervised Early Assessment of Bulk and Leukemic Stem Cell Measurable Residual Disease in Acute Myeloid Leukemia

PURPOSE

Acute myeloid leukemias (AML) are clonal diseases that develop from leukemic stem cells (LSC) that carry an independent prognostic impact on the initial response to induction chemotherapy, demonstrating the clinical relevance of LSC abundance in AML. In 2018, the European LeukemiaNet published recommendations for the detection of measurable residual disease (Bulk MRD) and suggested the exploration of LSC MRD and the use of multiparametric displays.

EXPERIMENTAL DESIGN

We evaluated the performance of unsupervised clustering for the post-induction assessment of bulk and LSC MRD in 155 patients with AML who received intensive conventional chemotherapy treatment.

RESULTS

The median overall survival (OS) for Bulk+ MRD patients was 16.7 months and was not reached for negative patients (HR, 3.82; P < 0.0001). The median OS of LSC+ MRD patients was 25.0 months and not reached for negative patients (HR, 2.84; P = 0.001). Interestingly, 1-year (y) and 3-y OS were 60% and 39% in Bulk+, 91% and 52% in Bulk-LSC+ and 92% and 88% in Bulk-LSC-.

CONCLUSIONS

In this study, we confirm the prognostic impact of post-induction multiparametric flow cytometry Bulk MRD in patients with AML. Focusing on LSCs, we identified a group of patients with negative Bulk MRD but positive LSC MRD (25.8% of our cohort) with an intermediate prognosis, demonstrating the interest of MRD analysis focusing on leukemic chemoresistant subpopulations.

Immunophenotypic characterization of acute leukemias in Bahia, Brazil

OBJECTIVE

To characterize the immunophenotypic profile of acute leukemias in the population of the state of Bahia, Brazil.

METHODS

This is a descriptive, retrospective study. From 2014 to 2018, 796 new cases of acute leukemia were evaluated. The data were obtained from analysis of reports and records of tests performed by flow cytometry immunophenotyping. All individuals of all age groups diagnosed as acute lymphoblastic leukemia or acute myeloid leukemia were included in the study. Demographic variables and expression of leukemia antigens were evaluated.

RESULTS

Most cases were diagnosed as acute myeloid leukemia and 42.7% as acute lymphoblastic leukemia. Significant differences were found in expression of markers in acute leukemias when age groups were compared, as well as in demographic characteristics. B-cell acute lymphoblastic leukemia was more prevalent than cases of T-cell origin. Assessing the aberrant markers in acute myeloid leukemias, the non-acute promyelocytic leukemia group presented expression of CD7 and CD56 as the most frequent ones. In B-cell acute lymphoblastic leukemia, the most frequent aberrant markers were CD66c, CD13 and CD33.

CONCLUSION

Significant differences were found as to several antigens when comparing adults and children, and these findings may contribute to future studies correlating the phenotypic profile to genetic characteristics and therapeutic response, including specific antigen therapies, which may be better targeted.

TLS/FUS-ERG fusion gene in acute leukemia and myelodysplastic syndrome evolved to acute leukemia: report of six cases and a literature review

To investigate the pathogenesis and the refractory/relapse mechanisms in patients with t(16;21)(p11;q22), we retrospectively analyzed the clinical data of six cases in our hospital and sixty-two cases reported in the literature. Among the patients in our hospital, five cases were diagnosed as acute leukemia, and one was myelodysplastic syndrome evolved to acute myeloid leukemia, harboring TLS/FUS-ERG fusion gene; all the cases were detected t(16;21)(p11;q22) translocation, and five cases showed additional chromosomal abnormalities. We firstly report a novel three-way translocation t(11;16;21)(q13;p11;q22), which may affect the prognosis of leukemia with TLS-ERG fusion gene because this patient shows a more satisfactory treatment effect and deeper remission. And we found patients with TLS-ERG are more likely to have bone and arthrosis pain. Besides, CD56 and CD123 were positive in these cases, which are related to poor prognosis and the character of refractory. Moreover, some gene mutations are involved, and GATA2 and SMAD4 mutations were identified when the disease progressed from myelodysplastic syndrome to leukemia. Among sixty-two patients reported in the literature, valid positive percent of CD56 and CD123 were 81% and 14.3%, respectively. Mutation of the RUNX1 gene was detected in four cases, and one patient had multiple mutations, including BCOR, PLCG1, DIS3, BRAF, JAK2, and JAK3. The prominent feature of leukemia carrying the TLS/FUS-ERG gene is its poor prognosis. The relevant mechanism includes new mutation, jumping translocation, different transcripts, and so on. The mechanism still acquaints scarcely, which requires further study.

Correlation Analysis and Prognostic Impacts of Biological Characteristics in Elderly Patients with Acute Myeloid Leukemia

Background

The significant heterogeneity of elderly AML patients’ biological features has caused stratification difficulties and adverse prognosis. This paper did a correlation study between their genetic mutations, clinical features, and prognosis to further stratify them.

Methods

90 newly diagnosed elderly acute myeloid leukemia (AML) patients (aged ≥60 years) who detected genetic mutations by next-generation sequencing (NGS) were enrolled between April 2015 and March 2021 in our medical center.

Results

A total of 29 genetic mutations were identified in 82 patients among 90 cases with a frequency of 91.1%. DNMT3A, BCOR, U2AF1, and BCORL1 mutations were unevenly distributed among different FAB classifications (p < 0.05). DNMT3A, IDH2, NPM1, FLT3-ITD, ASXL1, IDH1, SRSF2, BCOR, NRAS, RUNX1, U2AF1, MPO, and WT1 mutations were distributed differently when an immunophenotype was expressed or not expressed (p<0.05). NPM1 and FLT3-ITD had higher mutation frequencies in patients with normal chromosome karyotypes than abnormal chromosome karyotypes (p<0.001, p=0.005). DNMT3A and NRAS mutations predicted lower CR rates. DNMT3A, TP53, and U2AF1 mutations were related to unfavorable OS. TET2 mutation with CD123+, CD11b+ or CD34- predicted lower CR rate. IDH2+/CD34- predicted lower CR rate. ASXL1+/CD38+ and SRSF2+/CD123- predicted shorter OS.

Conclusion

The study showed specific correlations between elderly AML patients’ genetic mutations and clinical features, some of which may impact prognosis.

Recent advances in T-cell lymphoid neoplasms

T Cells comprise many subtypes of specified lymphocytes, and their differentiation and function take place in different tissues. This cellular diversity is also observed in the multiple ways T-cell transformation gives rise to a variety of T-cell neoplasms. This review covers the main types of T-cell malignancies and their specific characteristics, emphasizing recent advances at the cellular and molecular levels as well as differences and commonalities among them.

Engineered type 1 regulatory T cells designed for clinical use kill primary pediatric acute myeloid leukemia cells

Type 1 regulatory (Tr1) T cells induced by enforced expression of interleukin-10 (LV-10) are being developed as a novel treatment for chemotherapy-resistant myeloid leukemias. In vivo, LV-10 cells do not cause graft-versus-host disease while mediating graft-versus-leukemia effect against adult acute myeloid leukemia (AML). Since pediatric AML (pAML) and adult AML are different on a genetic and epigenetic level, we investigate herein whether LV-10 cells also efficiently kill pAML cells. We show that the majority of primary pAML are killed by LV-10 cells, with different levels of sensitivity to killing. Transcriptionally, pAML sensitive to LV-10 killing expressed a myeloid maturation signature. Overlaying the signatures of sensitive and resistant pAML onto the public NCI TARGET pAML dataset revealed that sensitive pAML clustered with M5 monocytic pAML and pAML with MLL rearrangement. Resistant pAML clustered with myelomonocytic leukemias and those bearing the core binding factor translocations inv(16) or t(8;21)(RUNX1- RUNX1T1). Furthermore, resistant pAML upregulated the membrane glycoprotein CD200, which binds to the inhibitory receptor CD200R1 on LV-10 cells. In order to examine if CD200 expression on target cells can impair LV-10 cell function, we overexpressed CD200 in myeloid leukemia cell lines ordinarily sensitive to LV-10 killing. Indeed, LV-10 cells degranulated less and killed fewer CD200-overexpressing cells compared to controls, indicating that pAML can utilize CD200 expression for immune evasion. Altogether, the majority of pAML are killed by LV-10 cells in vitro, supporting further LV-10 cell development as an innovative cell therapy for pAML.

DNAM-1/CD226 is functionally expressed on acute myeloid leukemia (AML) cells and is associated with favorable prognosis

DNAM-1 is reportedly expressed on cytotoxic T and NK cells and, upon interaction with its ligands CD112 and CD155, plays an important role in tumor immunosurveillance. It has also been reported to be functionally expressed by myeloid cells, but expression and function on malignant cells of the myeloid lineage have not been studied so far. Here we analyzed expression of DNAM-1 in leukemic cells of acute myeloid leukemia (AML) patients. We found substantial levels of DNAM-1 to be expressed on leukemic blasts in 48 of 62 (> 75%) patients. Interaction of DNAM-1 with its ligands CD112 and CD155 induced release of the immunomodulatory cytokines IL-6, IL-8 IL-10 and TNF-α by AML cells and DNAM-1 expression correlated with a more differentiated phenotype. Multivariate analysis did not show any association of DNAM-1 positivity with established risk factors, but expression was significantly associated with clinical disease course: patients with high DNAM-1 surface levels had significantly longer progression-free and overall survival compared to DNAM-1^low patients, independently whether patients had undergone allogenic stem cell transplantation or not. Together, our findings unravel a functional role of DNAM-1 in AML pathophysiology and identify DNAM-1 as a potential novel prognostic maker in AML.

High expression of CD56 may be associated with favorable overall survival in intermediate-risk acute myeloid leukemia

OBJECTIVES

Previous study (Br. J. Haematol. 2017; 176:498) reported that CD56 positive is associated with poor prognosis of patients with intermediate-risk acute myeloid leukemia (IR-AML). However, our data were inconsistent with the finding. Thus, in this study, we provided the different results to discuss.

METHODS

A total of 262 bone marrow transcriptomic data of IR-AML in the GSE12417-GPL96 and GSE71014-GPL-10558 from the Gene Expression Omnibus database (GEO) database, and 92 IR-AML patients from the cancer genome atlas (TCGA) database were obtained for prognostic analysis and validation.

RESULTS

Compared with low CD56 expression, IR-AML patients with high CD56 expression had a longer overall survival (OS) time and restricted mean survival time (RMST) and favorable OS rate in the GSE12417-GPL96 dataset. These results were confirmed in both GSE71014-GPL-10558 and TCGA datasets. Importantly, the inconsistency between our findings and the previous finding may be due to the following reasons: different detection methods, age stratification, countries, treatment options etc.

CONCLUSIONS

The prognostic value of CD56 expression in IR-AML may need to be comprehensively evaluated based on different detection methods, age stratification, countries, treatment options, and other factors. If confirmed, CD56 may be a biomarker for further risk stratification for IR-AML patients.

Quantitative analyses of CD7, CD33, CD34, CD56, and CD123 within the FLT3-ITD/NPM1-MUT myeloblastic/monocytic bulk AML blastic populations

The most frequent mutations in acute myeloid leukemia (AML) - FLT3-ITD and NPM1 - are associated with a specific immunophenotype. We evaluated the levels of surface antigens in an uninvestigated AML patient population according to the combination of FLT3-ITD/NPM1 mutations. Antigen levels were calculated as the geometric mean fluorescence index (MFI) ratio between myeloblasts or monoblasts/monocytes and a negative population for the specific antigen. In myeloblastic populations, FLT3-ITD cases presented CD7^high MFI values (p < .001), while NPM1-MUT cases presented CD33^high (p < .001), and CD34^low (p < .001) MFI values. Within the monoblastic/monocytic populations, CD56^high expression was observed only in the FLT3-WT/NPM1-MUT population (p=.003). The single common antigen expression between myeloblasts and monoblasts/monocytes was CD123^high expression only within the FLT3-ITD/NPM1-MUT subgroup. Our results present a subtle influence of FLT3-ITD/NPM1 mutations upon antigen expression profiles in myeloblasts vs monoblasts/monocytes, and we described a novel correlation between the presence of NPM1 and CD56^high values within bulk leukemic monoblasts/monocytes.

Lymphoid markers predict prognosis of pediatric and adolescent acute myeloid leukemia

Acute Myeloid Leukemia (AML) is a complex and highly aggressive disease. To characterize the prognostic factors of pediatric patients with AML relapse, a retrospective cohort study was performed to collect data from children and adolescents, at a hematological oncology reference center, over 11 years. We selected 51 cases of the disease, diagnosed and treated uniformly, divided into two groups: with complete remission (n = 33; 65 %) and with relapse (n = 18; 35 %). The groups were homogeneous concerning demographic characteristics and hematological parameters at diagnosis. AML M3 was the most common subtype (n = 19; 37 %) and was associated with a good prognosis. The highest rate of relapse was with AML M0 (n = 3 of 5 patients; 60 %). The most predominant gene mutation, FLT3-ITD, did not influence the prognosis in our study. The complete remission group presented a higher mean frequency of positive cells for the granulocytic marker CD13a at diagnosis. In cases with AML relapse, CD36, CD4, CD7, and CD22 were the most expressed markers. Increase incidence of recurrence was associated with CD7 (HR 1.035; p = 0.003), CD4 (HR 1.032, p = 0.001) and CD22 (HR 1.042; p = 0.049). Our results highlight the importance of analyzing immunophenotypic markers to help predict the outcome of AML in children and adolescents.

Aberrant myelomonocytic CD56 expression in Down syndrome is frequent and not associated with leukemogenesis

Children with Down syndrome (DS) are at an increased risk of developing transient abnormal myelopoiesis (TAM) and acute leukemia. Aberrant expression of CD56 has been observed on myeloid leukemic blasts in DS patients. In general, CD56 expression in acute myeloid leukemia (AML) is considered a promoter of leukemogenesis. We did a retrospective flow cytometric study to investigate mature myelomonocytic cell CD56 expression patterns in TAM, non-TAM, and leukemia cases with DS. Flow cytometric analysis showed that granulocyte and monocyte aberrant/dysplastic CD56 expression is an inherent characteristic of most DS patients irrespective of the presence of TAM or leukemia. Increased CD56 expression in monocyte and granulocyte populations in DS could be multifactorial; greater expression of RUNX1 secondary to the gene dose effect of trisomy 21 along with the maturational state of the cells are the potential contributors. Unlike AML seen in non-DS patients, CD56 overexpression in DS AML cases does not appear to play a role in leukemogenesis.

Blast counts are lower in the aspirate as compared to trephine biopsy in acute myeloid leukemia and myelodysplastic syndrome expressing CD56

INTRODUCTION

CD56 is aberrantly expressed in myeloid neoplasms including myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Considering the adhesion effects of CD56, blast quantification in bone marrow might depend on the technique used to obtain respective diagnostic specimens. Therefore, the objective of our study was to investigate the impact of CD56-expression on blast counts in myeloid neoplasms comparing bone marrow aspirates to biopsies.

METHODS

We retrospectively analyzed 75 patients diagnosed with MDS and AML. We compared patients with (n = 36) and without (n = 39) CD56-expression by flow cytometry with respect to their blast quantities assessed on bone marrow aspirates versus biopsies.

RESULTS

The frequency of CD56-expression on blasts correlated with higher blast counts on biopsies vs. aspirate smears (r_s  = 0.52; P = .001). This difference in blast counts was only significant in the CD56 high expressing subgroup (median 68%, 5.5%-95% in biopsy compared to median 32.5%, 1.5%-90% in aspirate; P < .01). The percentage of CD56-positive blasts among the total blast population was lower in the peripheral blood compared to bone marrow (median 31%, 6%-88% vs. 55%, 14%-98%; P = .016). The discrepancy in the blast count between the aspirate and trephine biopsy would have led to misclassification of four cases as MDS instead of AML, if diagnosis had based on the bone marrow aspirate blast count alone.

CONCLUSION

Counting blasts in bone marrow aspirates of CD56-positive AML and MDS may be linked to underestimation, potentially leading to misclassification of these myeloid neoplasms, and should therefore be adjusted considering the results obtained on trephine biopsies for reliable diagnosis.

A narrative review of central nervous system involvement in acute leukemias

Acute leukemias (both myeloid and lymphoblastic) are a group of diseases for which each year more successful therapies are implemented. However, in a subset of cases the overall survival (OS) is still exceptionally low due to the infiltration of leukemic cells in the central nervous system (CNS) and the subsequent formation of brain tumors. The CNS involvement is more common in acute lymphocytic leukemia (ALL), than in adult acute myeloid leukemia (AML), although the rates for the second case might be underestimated. The main reasons for CNS invasion are related to the expression of specific adhesion molecules (VLA-4, ICAM-1, VCAM, L-selectin, PECAM-1, CD18, LFA-1, CD58, CD44, CXCL12) by a subpopulation of leukemic cells, called “sticky cells” which have the ability to interact and adhere to endothelial cells. Moreover, the microenvironment becomes hypoxic and together with secretion of VEGF-A by ALL or AML cells the permeability of vasculature in the bone marrow increases, coupled with the disruption of blood brain barrier. There is a single subpopulation of leukemia cells, called leukemia stem cells (LSCs) that is able to resist in the new microenvironment due to its high adaptability. The LCSs enter into the arachnoid, migrate, and intensively proliferate in cerebrospinal fluid (CSF) and consequently infiltrate perivascular spaces and brain parenchyma. Moreover, the CNS is an immune privileged site that also protects leukemic cells from chemotherapy. CD56/NCAM is the most important surface molecule often overexpressed by leukemic stem cells that offers them the ability to infiltrate in the CNS. Although asymptomatic or with unspecific symptoms, CNS leukemia should be assessed in both AML/ALL patients, through a combination of flow cytometry and cytological analysis of CSF. Intrathecal therapy (ITT) is a preventive measure for CNS involvement in AML and ALL, still much research is needed in finding the appropriate target that would dramatically lower CNS involvement in acute leukemia.

Normal or reactive minor cell populations in bone marrow and peripheral blood mimic minimal residual leukemia by flow cytometry

BACKGROUND

Measurable residual disease (MRD) is a strong independent poor prognostic factor for acute leukemia. Multiparameter flow cytometry (FCM) is a commonly used MRD detection method. However, FCM MRD detection is not well standardized, and the interpretation is subjective. There are normal/reactive minor cell populations in bone marrow (BM) and peripheral blood (PB), which could be confused with MRD.

METHODS

The FCM data of 231 BM and 44 PB pediatric samples performed in a recent 15-month period were retrospectively reviewed. These samples were from 56 B-lymphoblastic leukemia (B-ALL) patients, 11 T-lymphoblastic leukemia (T-ALL) patients, 28 acute myeloid leukemia (AML)/myelodysplastic syndrome (MDS) patients, 44 cytopenia/leukocytosis patients, and five patients with mycosis fungoides.

RESULTS

There were over 10 normal or reactive minor cell populations identified with certain phenotypes mimicking MRD of acute leukemia. These mimickers included CD19+ NK cells, CD22+ basophils, CD22+ dendritic cells (DCs), and plasma cells for B-ALL MRD; CD4/8 double-negative T cells, CD4/8 double-positive T cells, cytoplasmic CD3+ NK cells, CD2- T cells, CD7- T cells, CD5- gamma delta T cells, CD56+ NKT cells for T-ALL MRD; CD33+ NK cells, CD117+ NK cells, basophils, plasmacytoid DCs, non-classical monocytes, CD56+ and/or CD61+ monocytes for AML MRD.

CONCLUSIONS

These data confirm the presence of a variety of normal/reactive minor cell populations that could mimic MRD of acute leukemia by FCM. Recognizing these MRD mimickers is important for correct FCM MRD interpretation.

Contactin 1: An Important and Emerging Oncogenic Protein Promoting Cancer Progression and Metastasis

Even with recent progress, cancer remains the second leading cause of death, outlining a need to widen the current understanding on oncogenic factors. Accumulating evidence from recent years suggest Contactin 1 (CNTN1)'s possession of multiple oncogenic activities in a variety of cancer types. CNTN1 is a cell adhesion molecule that is dysregulated in many human carcinomas and plays important roles in cancer progression and metastases. Abnormalities in CNTN1 expression associate with cancer progression and poor prognosis. Mechanistically, CNTN1 functions in various signaling pathways frequently altered in cancer, such as the vascular endothelial growth factor C (VEGFC)-VEGF receptor 3 (VEFGR3)/fms-related tyrosine kinase 4 (Flt4) axis, phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT), Notch signaling pathway and epithelial-mesenchymal transition (EMT) process. These oncogenic events are resulted via interactions between tumor and stroma, which can be contributed by CNTN1, an adhesion protein. CNTN1 expression in breast cancer correlates with the expression of genes functioning in cancer-stroma interactions and skeletal system development. Evidence supports that CNTN1 promotes cancer-stromal interaction, resulting in activation of a complex network required for cancer progression and metastasis (bone metastasis for breast cancer). CNTN1 inhibitions has been proven to be effective in experimental models to reduce oncogenesis. In this paper, we will review CNTN1's alterations in cancer, its main biochemical mechanisms and interactions with its relevant cancer pathways.

Combination of FLT3-ITD Allelic Ratio, NPM1 Mutation, and Immunophenotypic Markers to Modulate Outcome Prediction in Patients with Normal Karyotype Acute Myelogenous Leukemia Undergoing Hematopoietic Stem Cell Transplantation

NPM1 mutation status and the allelic ratio (AR) of FLT3-internal tandem duplication (FLT3-ITD) are routinely tested for disease risk stratification in patients with normal karyotype (NK) acute myelogenous leukemia (AML); however, the predictive impact of immunophenotypic markers on different NPM1/FLT3 genotypes remains unclear. We performed a retrospective analysis of 423 patients with NK-AML subclassified into groups based on NPM1/FLT3 genotype. Allogeneic hematopoietic stem cell transplantation (HSCT) was performed in 124 of 423 patients (29%) and was significantly associated with longer event-free survival (EFS) and overall survival (OS), except for patients with the favorable genotype, defined as mutated NPM1 (NPM1^mut) combined with normal FLT3 status (FLT3-ITD^neg) or FLT3-ITD AR <.5 (FLT3-ITD^low). A subset of AML patients bearing the favorable NPM1^mut/FLT3-ITD^neg/low genotype share similar outcomes with AML patients who have the intermediate FLT3/NPM1 genotype defined by normal NPM1 (NPM1^wt) and FLT3-ITD^neg/low. In these individuals, the lack of CD13 expression (CD13^neg) was associated with shorter EFS (P = .041) and OS (P = .017). CD13^neg was an independent predictor for shorter OS (hazard ratio, 1.985; P = .028).

Impact of CD56 Continuously Recognizable as Prognostic Value of Acute Promyelocytic Leukemia: Results of Multivariate Analyses in the Japan Adult Leukemia Study Group (JALSG)-APL204 Study and a Review of the Literature

BACKGROUND

After long-term analysis of the JALSG-APL204 study we recently reported that maintenance therapy with tamibarotene was more effective than all-trans retinoic acid (ATRA) by reducing relapse in APL patients. Here, the clinical significance of other important prognostic factors was evaluated with multivariate analyses.

PATIENTS AND METHODS

Newly diagnosed acute promyelocytic leukemia (APL) patients were registered with the study. Induction was composed of ATRA and chemotherapy. Patients who achieved molecular remission after consolidation were randomly assigned to maintenance with tamibarotene or ATRA.

RESULTS

Of the 344 eligible patients, 319 (93%) achieved complete remission (CR). After completing consolidation, 269 patients underwent maintenance random assignment-135 to ATRA, and 134 to tamibarotene. By multivariate analysis, overexpression of CD56 in blast was an independent unfavorable prognostic factor for relapse-free survival (RFS) (p = 0.006) together with more than 10.0 × 10⁹/L WBC counts (p = 0.001) and the ATRA arm in maintenance (p = 0.028). Of all phenotypes, CD56 was related most clearly to an unfavorable prognosis. The CR rate, mortality rate during induction and overall survival of CD56⁺ APL were not significantly different compared with CD56^- APL. CD56 is continuously an independent unfavorable prognostic factor for RFS in APL patients treated with ATRA and chemotherapy followed by ATRA or tamibarotene maintenance therapy.

ERK Activity in Immature Leukemic Cells Drives Clonal Selection during Induction Therapy for Acute Myeloid Leukemia

Selection of resistant clones following intensive chemotherapy is a common obstacle for cure in many cancers, particularly in acute myeloid leukemia (AML). In AML, clone-specific sensitivity to chemotherapy varies even within the same patient. Multiple mutations and genetic aberrations are associated with clones surviving chemotherapy. The current study explored the role of activated signaling pathways in chemoresistance as a function of cell maturation, reflected by CD34 expression. In-vitro, Kasumi-1 leukemic cell line, sorted by CD34 expression, showed increased apoptosis only in the CD34⁻ subpopulation after exposure to cytosine arabinoside (Ara-C) or daunorubicin. The resistant CD34⁺ subset demonstrated higher expression of ERK1/2 and BCL-2 proteins than CD34⁻ cells. MEK1/2 inhibition elevated Ara-C ability to induce apoptosis in CD34⁺ cells, suggesting that MEK1/2-ERK1/2 is surviving signaling, which correlates to cell maturation levels and plays a role in chemoresistance. Deep sequencing of sorted CD34^+/− populations, both derived from the same patient samples, demonstrated various subclonal distribution of NPM1, DNMT3A and FLT3-ITD mutations. Interestingly, in these samples, p-ERK levels and apoptosis rates following chemotherapy exposure significantly differed between CD34^+/− populations. Hence, clones may be selected due to their ability to escape apoptosis rather than a direct effect of chemotherapy on a specific mutated clone.

Prognostic relevance of a blastic plasmacytoid dendritic cell neoplasm-like immunophenotype in cytogenetically normal acute myeloid leukemia patients

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a poor prognosis myeloid malignancy characterized by an atypical phenotype (CD123+, CD56+, and CD4+). We reported that BPDCN-like phenotype (CD123+ and either CD56+ or CD4+ or both) confers poor prognosis to acute myeloblastic leukemia (AML) patients with mutated NPM1. Here, we evaluated the incidence and the prognostic relevance of BPDCN-like phenotype in cytogenetically normal AML (CN-AML) patients. From 2006 to 2016, 83 young (age <60 yrs), consecutive, CN-AML patients underwent intensive treatment. Fifteen patients (18%) showed a BPDCN-like phenotype with no difference between NPM1-mutated (mut) and NPM1-wt patients. It did not significantly affect survival neither in the whole cohort, nor in NPM1-wt patients. However, as reported, it conferred a dismal prognosis in NPM1-mut AML (p < 0.001), irrespectively of the mutational status for FLT3-ITD. In conclusion we show that BPDCN-like phenotype displays a negative prognostic relevance only in NPM1-mutated AML.

Clinical Significance of CD200 and CD56 Expression in Patients with Acute Myeloid Leukemia

BACKGROUND

Acute myeloid leukemia (AML) escape from immunosurveillance by immunosuppression. CD200 and CD56 expression represented an independent prognostic factor in many hematological malignancies but its importance in AML patients remains to be identified.

METHODS

CD200 and CD56 expression were assessed in the bone marrow blasts for Fifty-two (52) newly diagnosed AML by flowcytometry before start of therapy.

RESULTS

CD200+ expression was reported in 28.8% of patients while 17.3% of patients showed CD56+ expression. M4 FAB revealed high frequency of both CD200+ and CD56+ expression. The overall survival of CD200+ patients was 19.2% compared to 35.3% in CD200- (P= 0.049). On the other hand, CD56+ patients had the lowest complete remission rate (22.2% vs. 53.4%). In addition, CD56+ population had significant bad influence on overall survival than those of CD56- population (11.1 % vs. 35.5 %, P= 0.047).

CONCLUSIONS

CD200 and CD56 positive expression by myeloblasts at diagnosis denote poor prognostic indicator and correlated with poor cytogenetic findings. CD200 could be used as therapeutic target in AML.<br />.

Deciphering the Significance of CD56 Expression in Pediatric Acute Myeloid Leukemia: A Report from the Children's Oncology Group

BACKGROUND

In patients with acute myeloid leukemia (AML), CD56 expression has been associated with adverse clinical outcome. We reported on a phenotype associated with very poor prognosis (RAM) in children enrolled in the Children's Oncology Group trial AAML0531 (Brodersen et al. Leukemia 30 (2016) 2077-2080). RAM is also characterized in part by high-intensity expression of the CD56 antigen. Herein, we investigate underlying biological and clinical differences among CD56-positive AMLs for patients in AAML0531.

METHODS

For 769 newly diagnosed pediatric patients with de novo AML enrolled in AAML0531, bone marrow specimens were submitted for flow cytometric analysis. For each patient, an immunophenotypic expression profile (IEP) was defined by mean fluorescent intensities of assayed surface antigens. Unsupervised hierarchical clustering analysis (HCA) was completed to group patients with similar immunophenotypes. Clusters were then evaluated for CD56 expression. Principal component analysis (PCA) was subsequently applied to determine whether CD56-positive patient groups were nonoverlapping.

RESULTS

HCA of IEPs revealed three unique phenotypic clusters of patients with CD56-positive AML, and PCA showed that these three cohorts are distinct. Cohort 1 (N = 77) showed a prevalence of t(8;21) patients (72%), Cohort 2 (N = 52) a prevalence of 11q23 patients (69%), and Cohort 3 (RAM) (N = 16) a prevalence of patients with co-occurrence of the CBFA2T3-GLIS2 fusion transcript (63%). The 5-year event-free survival (EFS) for Cohorts 1, 2, and 3 were 69, 39, and 19%, respectively.

CONCLUSIONS

When leukemia is considered by its multidimensional immunophenotype and not by the expression of a single antigen, correlations are seen between genotype and there are significant differences in patient outcomes. © 2019 International Clinical Cytometry Society.

GScluster: network-weighted gene-set clustering analysis

Background

Gene-set analysis (GSA) has been commonly used to identify significantly altered pathways or functions from omics data. However, GSA often yields a long list of gene-sets, necessitating efficient post-processing for improved interpretation. Existing methods cluster the gene-sets based on the extent of their overlap to summarize the GSA results without considering interactions between gene-sets.

Results

Here, we presented a novel network-weighted gene-set clustering that incorporates both the gene-set overlap and protein-protein interaction (PPI) networks. Three examples were demonstrated for microarray gene expression, GWAS summary, and RNA-sequencing data to which different GSA methods were applied. These examples as well as a global analysis show that the proposed method increases PPI densities and functional relevance of the resulting clusters. Additionally, distinct properties of gene-set distance measures were compared. The methods are implemented as an R/Shiny package GScluster that provides gene-set clustering and diverse functions for visualization of gene-sets and PPI networks.

Conclusions

Network-weighted gene-set clustering provides functionally more relevant gene-set clusters and related network analysis.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5738-6) contains supplementary material, which is available to authorized users.

Oncogenic Deregulation of Cell Adhesion Molecules in Leukemia

Numerous cell⁻cell and cell⁻matrix interactions within the bone marrow microenvironment enable the controlled lifelong self-renewal and progeny of hematopoietic stem and progenitor cells (HSPCs). On the cellular level, this highly mutual interaction is granted by cell adhesion molecules (CAMs) integrating differentiation, proliferation, and pro-survival signals from the surrounding microenvironment to the inner cell. However, cell⁻cell and cell⁻matrix interactions are also critically involved during malignant transformation of hematopoietic stem/progenitor cells. It has become increasingly apparent that leukemia-associated gene products, such as activated tyrosine kinases and fusion proteins resulting from chromosomal translocations, directly regulate the activation status of adhesion molecules, thereby directing the leukemic phenotype. These observations imply that interference with adhesion molecule function represents a promising treatment strategy to target pre-leukemic and leukemic lesions within the bone marrow niche. Focusing on myeloid leukemia, we provide a current overview of the mechanisms by which leukemogenic gene products hijack control of cellular adhesion to subsequently disturb normal hematopoiesis and promote leukemia development.

NCAM1 (CD56) promotes leukemogenesis and confers drug resistance in AML

Neural cell adhesion molecule 1 (NCAM1; CD56) is expressed in up to 20% of acute myeloid leukemia (AML) patients. NCAM1 is widely used as a marker of minimal residual disease; however, the biological function of NCAM1 in AML remains elusive. In this study, we investigated the impact of NCAM1 expression on leukemogenesis, drug resistance, and its role as a biomarker to guide therapy. Beside t(8;21) leukemia, NCAM1 expression was found in most molecular AML subgroups at highly heterogeneous expression levels. Using complementary genetic strategies, we demonstrated an essential role of NCAM1 in the regulation of cell survival and stress resistance. Perturbation of NCAM1 induced cell death or differentiation and sensitized leukemic blasts toward genotoxic agents in vitro and in vivo. Furthermore, Ncam1 was highly expressed in leukemic progenitor cells in a murine leukemia model, and genetic depletion of Ncam1 prolonged disease latency and significantly reduced leukemia-initiating cells upon serial transplantation. To further analyze the mechanism of the NCAM1-associated phenotype, we performed phosphoproteomics and transcriptomics in different AML cell lines. NCAM1 expression strongly associated with constitutive activation of the MAPK-signaling pathway, regulation of apoptosis, or glycolysis. Pharmacological inhibition of MEK1/2 specifically inhibited proliferation and sensitized NCAM1⁺ AML cells to chemotherapy. In summary, our data demonstrate that aberrant expression of NCAM1 is involved in the maintenance of leukemic stem cells and confers stress resistance, likely due to activation of the MAPK pathway. Targeting MEK1/2 sensitizes AML blasts to genotoxic agents, indicating a role for NCAM1 as a biomarker to guide AML treatment.

Pediatric acute myeloid leukemia with t(7;21)(p22;q22)

The t(7;21)(p22;q22) resulting in RUNX1-USP42 fusion, is a rare but recurrent cytogenetic abnormality associated with acute myeloid leukemia (AML) and myelodysplastic syndromes. The prognostic significance of this translocation has not been well established due to the limited number of patients. Herein, we report three pediatric AML patients with t(7;21)(p22;q22). All three patients presented with pancytopenia or leukopenia at diagnosis, accompanied by abnormal immunophenotypic expression of CD7 and CD56 on leukemic blasts. One patient had t(7;21)(p22;q22) as the sole abnormality, whereas the other two patients had additional numerical and structural aberrations including loss of 5q material. Fluorescence in situ hybridization analysis on interphase cells or sequential examination of metaphases showed the RUNX1 rearrangement and confirmed translocation 7;21. Genomic SNP microarray analysis, performed on DNA extracted from the bone marrow from the patient with isolated t(7;21)(p22;q22), showed a 32.2 Mb copy neutral loss of heterozygosity (cnLOH) within the short arm of chromosome 11. After 2-4 cycles of chemotherapy, all three patients underwent allogeneic hematopoietic stem cell transplantation (HSCT). One patient died due to complications related to viral reactivation and graft-versus-host disease. The other two patients achieved complete remission after HSCT. Our data displayed the accompanying cytogenetic abnormalities including del(5q) and cnLOH of 11p, the frequent pathological features shared with other reported cases, and clinical outcome in pediatric AML patients with t(7;21)(p22;q22). The heterogeneity in AML harboring similar cytogenetic alterations may be attributed to additional uncovered genetic lesions.

CD56 and CD11b Positivity with Low Smac/DIABLO Expression as Predictors of Chemoresistance in Acute Myeloid Leukaemia: Flow Cytometric Analysis

Background: Resistance to chemotherapy is a major obstacle to curing acute myeloid leukaemia (AML), and several antigens are claimed to play primary roles in this resistance. Purpose: The aim of this study was to evaluate the roles of CD56, CD11b and Smac/DIABLO gene expression levels as prognostic markers of the clinical outcome, response to chemotherapy and survival of AML patients. Materials and Methods: A cross-sectional observational study was conducted on 60 naïve-AML patients who received induction therapy with mitoxantrone and cytarabine combined with a high dose of cytarabine. The CD56,CD11b and Smac/DIABLO expression levels were assessed using flow cytometry at diagnosis and were analysed for correlation with the possible associated risk factors, response to chemotherapy, and median duration of disease-free survival (DFS) and overall survival (OS). Results: The overall results revealed that AML patients who exhibited positive expression for CD56 and CD11b had short median durations of DFS and OS.(P = 0.019, 0.006, 0.029 and 0.024, respectively). Additionally, low Smac/DIABLO expression had a negative impact on treatment outcome in terms of CR rate (p=0.012) and reduced DFS (p=0.000) and OS(p=0.000) values. Conclusions: CD56 and CD11b positivity and low Smac/DIABLO expression are important predictive factors for the occurrence of chemoresistance, in addition to other risk factors, among AML patients.

Expression of CD56 defines a distinct subgroup in childhood T-ALL with inferior outcome. Results of the ALL-BFM 2000 trial

This study reports the prognostic impact of the expression of the natural killer cell marker CD56 in a large series of risk-adapted paediatric patients with T cell acute lymphoblastic leukaemia (T-ALL; n = 493) treated within the ALL-Berlin-Frankfurt-Münster (BFM) 2000 protocol. The immunophenotype was analysed centrally at diagnosis using flow cytometry and correlated with clinical parameters and outcome. CD56 expression was detected in 7·1% and early T-cell precursor (ETP) phenotype in 6·7% of all T-ALL patients. The percentage of ETP in the CD56+ T-ALL cohort was 4-fold higher than in the whole cohort. CD56+ T-ALL frequently expressed the progenitor marker CD34 and myeloid antigens CD13 and CD33. The 5-year event-free survival (EFS) rates for the European Group for the Immunological classification of Leukaemias/World Health Organization subgroups and the ETP phenotype were not statistically different. By contrast, patients with CD56 expression had a significantly reduced EFS (60 ± 8%) and overall survival (60 ± 8%) at 5 years, with a hazard ratio of 2·46 (P = 0·002) and 2·99 (P < 0·001), respectively. Moreover, CD56 expression in combination with the minimal residual disease (MRD)-based high risk assignment defined a population with a 'very-high' risk probability of relapse in the ALL-BFM 2000 trial. The CD56 marker has the potential to augment MRD-based risk stratification and may serve as a molecular target for antibody-based treatment strategies in childhood T-ALL.

Adverse outcome of AML with aberrant CD16 and CD56 NK cell marker expression

Natural killer cells mediate antibody-dependent cell-mediated cytotoxicity, and CD16 exerts key functions to induce antibody-dependent cell-mediated cytotoxicity response. Because the prognostic relevance of aberrant CD16 expression in AML patients at diagnosis is unknown, we analyzed 325 AML patients undergoing intensive chemotherapy for aberrant CD16+ and CD56+ natural killer-cell marker expression. CD56+ AML patients had inferior median event-free (EFS; P = 0.0699) and overall survival (OS; 10.9 versus 20.6 months; P = 0.0132). Patients expressing CD16 had worse median EFS (P = 0.0622) and OS (13.0 versus 45.9 months; P = 0.0277). EFS for CD16+/CD56+ patients was 5.7 months compared with 7.1 months for CD16-/CD56- (P = 0.3690), and OS was 10.6 months for CD16+/CD56+ patients compared with 52.2 months for CD16-/CD56- patients (P = 0.0311). Patients with CD16+/CD56+ expression had a lower probability to achieve complete remission after 2 induction cycles (52% versus 72%). Our data suggest that AML patients with aberrant CD16 and CD56 expression have adverse survival outcomes.

Therapeutic Antibodies for Myeloid Neoplasms-Current Developments and Future Directions

Therapeutic monoclonal antibodies (mAbs) such as antibody-drug conjugates, ligand-receptor antagonists, immune checkpoint inhibitors and bispecific T cell engagers have shown impressive efficacy in the treatment of multiple human cancers. Numerous therapeutic mAbs that have been developed for myeloid neoplasms, including acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS), are currently investigated in clinical trials. Because AML and MDS originate from malignantly transformed hematopoietic stem/progenitor cells-the so-called leukemic stem cells (LSCs) that are highly resistant to most standard drugs-these malignancies frequently relapse and have a high disease-specific mortality. Therefore, combining standard chemotherapy with antileukemic mAbs that specifically target malignant blasts and particularly LSCs or utilizing mAbs that reinforce antileukemic host immunity holds great promise for improving patient outcomes. This review provides an overview of therapeutic mAbs for AML and MDS. Antibody targets, the molecular mechanisms of action, the efficacy in preclinical leukemia models, and the results of clinical trials are discussed. New developments and future studies of therapeutic mAbs in myeloid neoplasms will advance our understanding of the immunobiology of these diseases and enhance current therapeutic strategies.

A Rare t(5;11)(q35;q13) Translocation in an Elderly Patient With Acute Myeloid Leukemia With Maturation: A Case Report

The t(5;11)(q35;q13) reciprocal translocation is a rare chromosomal abnormality that can arise in myeloid neoplasms, mainly in children and younger adults. Here, we report a case of acute myeloid leukemia with maturation, involving an 85-year-old, in which the tumor cells harbored the t(5;11)(q35;q13) chromosomal abnormality. We also address the diagnostic and immunophenotypic characteristics of acute myeloid leukemia involving t(5;11)(q35;q13), along with a review of the literature.

Prognostic impact of CD200 and CD56 expression in adult acute lymphoblastic leukemia patients

BACKGROUND

The aim of the study is to determine the prognostic relevance of CD200/ CD56 expression in adult acute lymphoblastic leukemia patients.

METHODS

The expression of CD200 and CD56 by blast cells was assessed by flow cytometry before the start of chemotherapy in 70 B-ALL patients.

RESULTS

Positive expression of CD200 was detected in forty-six patients (66%) and CD56 was detected in 7 patients (10%) out of 70 patients, respectively. Only three patients (4.3%) had co-expression for CD200⁺ and CD56⁺. Splenomegaly and thrombocytopenia were frequently observed more in CD200⁺ patients. Increased frequency of CD34⁺ was associated with CD200⁺and CD56⁺ patients. The CD200⁺ and CD56⁺ subgroups of B-ALL patients had inferior OS and disease free survival compared to CD 200^- and CD 56^- patients.

CONCLUSIONS

CD200⁺ and/or CD56⁺ positive expression in B-ALL patients at diagnosis is a poor prognostic biomarker. Identification of CD200⁺ and CD56⁺ expression at diagnosis is recommended for a better stratification of adult B-ALL patients.

Immunophenotypic, cytogenetic, and mutational characterization of cell lines derived from myelodysplastic syndrome patients after progression to acute myeloid leukemia

Leukemia cell lines have been widely used in the hematology field to unravel mechanistic insights and to test new therapeutic strategies. Myelodysplastic syndromes (MDS) comprise a heterogeneous group of diseases that are characterized by ineffective hematopoiesis and frequent progress to acute myeloid leukemia (AML). A few cell lines have been established from MDS patients after progression to AML but their characterization is incomplete. Here we provide a detailed description of the immunophenotypic profile of the MDS-derived cell lines SKK-1, SKM-1, F-36P; and MOLM-13. Specifically, we analyzed a comprehensive panel of markers that are currently applied in the diagnostic routine for myeloid disorders. To provide high-resolution genetic data comprising copy number alterations and losses of heterozygosity we performed whole genome single nucleotide polymorphism-based arrays and included the cell line OHN-GM that harbors the frequent chromosome arm 5q deletion. Furthermore, we assessed the mutational status of 83 disease-relevant genes. Our results provide a resource to the MDS and AML field that allows researchers to choose the best-matching cell line for their functional studies. © 2016 Wiley Periodicals, Inc.

Immunophenotype Discovery, Hierarchical Organization, and Template-Based Classification of Flow Cytometry Samples

We describe algorithms for discovering immunophenotypes from large collections of flow cytometry samples and using them to organize the samples into a hierarchy based on phenotypic similarity. The hierarchical organization is helpful for effective and robust cytometry data mining, including the creation of collections of cell populations’ characteristic of different classes of samples, robust classification, and anomaly detection. We summarize a set of samples belonging to a biological class or category with a statistically derived template for the class. Whereas individual samples are represented in terms of their cell populations (clusters), a template consists of generic meta-populations (a group of homogeneous cell populations obtained from the samples in a class) that describe key phenotypes shared among all those samples. We organize an FC data collection in a hierarchical data structure that supports the identification of immunophenotypes relevant to clinical diagnosis. A robust template-based classification scheme is also developed, but our primary focus is in the discovery of phenotypic signatures and inter-sample relationships in an FC data collection. This collective analysis approach is more efficient and robust since templates describe phenotypic signatures common to cell populations in several samples while ignoring noise and small sample-specific variations. We have applied the template-based scheme to analyze several datasets, including one representing a healthy immune system and one of acute myeloid leukemia (AML) samples. The last task is challenging due to the phenotypic heterogeneity of the several subtypes of AML. However, we identified thirteen immunophenotypes corresponding to subtypes of AML and were able to distinguish acute promyelocytic leukemia (APL) samples with the markers provided. Clinically, this is helpful since APL has a different treatment regimen from other subtypes of AML. Core algorithms used in our data analysis are available in the flowMatch package at www.bioconductor.org. It has been downloaded nearly 6,000 times since 2014.

Clinical impact of CD200 expression in patients with acute myeloid leukemia and correlation with other molecular prognostic factors

CD200, a protein belonging to the immunoglobulin superfamily, has been associated with a poor prognosis in lymphoproliferative disorders and in acute leukemia. We studied the expression of CD200 in a series of 244 patients with diagnosis of acute myeloid leukemia (AML), to evaluate its impact on outcome and its possible association with other known prognostic factors.

CD200 was found in 136/244 (56%) patients, in 41 of whom (30%) with high intensity of expression (MFI ≥ 11). CD200 was more frequent in secondary compared to de novo leukemia (p = 0.0006), in CD34 positive cases (p = 0.00001), in Bcl2 overexpressing cases (p = 0.01), in those wild-type Flt3 (p = 0.004) and with favorable or unfavorable compared to intermediate karyotype (p = 0.0003). CD200+ patients have a two-fold lower probability to attain complete remission, both in univariate (p = 0.006) and multivariate (p = 0.04) analysis. The negative impact of CD200 was found also in overall survival (p = 0.02) and was correlated with the intensity of expression of the molecule (p = 0.024). CD200 has an additive negative impact on survival in patients with unfavorable cytogenetic (p = 0.046) and in secondary leukemia (p = 0.05), and is associate with a worsening of outcome in patients with favorable biological markers, such as mutated NPM (p = 0.02), wild-type Flt3 (p = 0.034), negativity of CD34 (p = 0.03) and of CD56 (p = 0.03).

In conclusion, CD200 is emerging as both a prognostic factor and a potential target of novel therapeutic approaches for AML, aiming to reverse the “do not eat me” signal of CD200 or to manipulate the suppressive immune microenvironment induced by CD200 binding to its receptor.