CD56 expression predicts occurrence of CNS disease in acute lymphoblastic leukemia

Expression and Clinical Significance of CD30 and CD56 in Lymphoblastic Lymphoma: A Retrospective Analysis on Paraffin-Embedded Tissues by Immunohistochemistry

Background: We evaluated CD30 and CD56 expression in lymphoblastic lymphoma (LBL) and correlated the results with clinicopathological features and prognosis. Methods: Immunohistochemical (IHC) staining was performed on 85 formalin-fixed paraffin-embedded LBL specimens using two CD30 clones and one CD56 antibody clone. Results: Weak and diffuse expression of CD30 was expressed in 4.7% (clone Ber-H2) or 14.1% (clone EPR4102) in LBL, while CD56 was expressed in 24.7%. CD30 and CD56 expression correlated with lactate dehydrogenase levels. CD56-positive expression was closely associated with an unfavorable prognosis. Although CD30 expression exhibited a trend toward poorer overall survival, it did not reach statistical significance. Conclusion: CD56 is a potential negative prognostic marker. These findings suggest that CD30 and CD56 targeted therapies could be potential therapeutic targets for LBL patients.

CD56-positive diffuse large B-cell lymphoma: comprehensive analysis of clinical, pathological, and molecular characteristics with literature review

BACKGROUND

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma. The expression of CD56 in DLBCL is highly unusual. Little is known about its incidence and clinical importance. So far, no genetic profiling was performed in CD56 positive DLBCL.

PATIENTS AND METHODS

Tissue microarrays have been constructed, sectioned, and stained by H&E and immunohistochemistry for 229 patients with DLBCL diagnosed 2008-2017. For CD56 positive cases, clinical data was collected including age at diagnosis, stage of the disease, International Prognostic Index (IPI) score, treatment scheme and number of chemotherapy cycles, radiation therapy, treatment outcome, and possible relapse of the disease. Overall survival (OS) and progression-free survival (PFS) were calculated. For four patients, RNA was extracted and targeted RNA (cDNA) sequencing of 125 genes was performed with the Archer FusionPlex Lymphoma kit.

RESULTS

CD56 expression was found in 7 cases (3%). The intensity of expression varied from weak to moderate focal, to very intensive and diffuse. All patients had de novo DLBCL. The median age at the time of diagnosis was 54.5 years. Five of them were women and 2 males. According to the Hans algorithm, 6 patients had the germinal centre B cells (GBC) type and one non-GBC (activated B-cell [ABC]) type, double expressor. Genetic profiling of four patients according to Schmitz's classification showed that 1 case was of the BN2 subtype, 1 of EZB subtype, 2 were unclassified. The six treated patients reached a complete response and did not experience progression of the disease during the median follow-up period of 80.5 months.

CONCLUSIONS

We report on one of the largest series of CD56+DLBCL with detailed clinicopathological data and for the first time described genetical findings in a limited number of patients. Our results show that CD56 expression is rare, but seems to be present in prognostic favourable subtypes of DLBCL not otherwise specified (NOS) as tested by immunohistochemical or genetic profiling.

Central Nervous System Involvement in Adults with Acute Leukemia: Diagnosis, Prevention, and Management

PURPOSE OF REVIEW

Recent treatment advances in both acute myeloid leukemia and acute lymphoblastic leukemia have drastically improved outcomes for these diseases, but central nervous system (CNS) relapses still occur. Treatment of CNS disease can be challenging due to the impermeability of the blood-brain barrier to many systemic therapies.

RECENT FINDINGS

The diagnosis of CNS leukemia relies on assessment of clinical symptoms, cerebrospinal fluid sampling for conventional cytology and/or flow cytometry, and neuroimaging. While treatment of CNS leukemia with systemic or intrathecal chemotherapy and/or radiation can be curative in some patients, these modalities can also lead to serious toxicities. In the modern era, prophylaxis with intrathecal chemotherapy is the most important strategy to prevent CNS relapses in high risk patients. Accurate risk stratification tools and the use of risk-adapted prophylactic therapy are imperative to improving the outcomes of patients with acute leukemias and preventing the development of CNS leukemia.

Metabolic Reprogramming and Cell Adhesion in Acute Leukemia Adaptation to the CNS Niche

Involvement of the Central Nervous System (CNS) in acute leukemia confers poor prognosis and lower overall survival. Existing CNS-directed therapies are associated with a significant risk of short- or long-term toxicities. Leukemic cells can metabolically adapt and survive in the microenvironment of the CNS. The supporting role of the CNS microenvironment in leukemia progression and dissemination has not received sufficient attention. Understanding the mechanism by which leukemic cells survive in the nutrient-poor and oxygen-deprived CNS microenvironment will lead to the development of more specific and less toxic therapies. Here, we review the current literature regarding the roles of metabolic reprogramming in leukemic cell adhesion and survival in the CNS.

Clinical, immunophenotypic and genomic findings of NK lymphoblastic leukemia: a study from the Bone Marrow Pathology Group

Natural killer (NK) cells are lymphocytes of the native immune system that play a pivotal role in host defense and immune surveillance. While the conceptual view of NK-neoplasms is evolving, little is known about the rare NK lymphoblastic leukemia (NK-LL), which remains as a provisional entity in the 2016 WHO Classification. The goal of this study is to characterize NK-LL cases and compare with other CD56 co-expressing acute leukemias. We identified 105 cases, diagnosed as NK-LL (6), CD56+ acute undifferentiated leukemia (AUL) (6), CD56+ T-lymphoblastic leukemia (T-LL) (51), and CD56+ acute myeloid leukemia (AML) (42). Compared to AUL patients, NK-LL patients were significantly younger (p = 0.021) and presented with higher white blood cell (WBC) (p = 0.037) and platelet counts (p = 0.041). Flow cytometry showed more frequent expression of cytoplasmic CD3 (cCD3, p = 0.064) and CD33, (p = 0.065), while HLA-DR was significantly absent from NK-LL (p = 0.035) compared to AUL. Compared to T-ALL, NK-LL cases showed less frequent cCD3 (p = 0.002), CD4 (p = 0.051), and CD10 expression (p = 0.06). The frequency of abnormal karyotypes was similar between NK-LL, AUL, and T-ALL. The mutational profile differed in four leukemia groups, with a significance enrichment of NOTCH1 (p = 0.002), ETV6 (p = 0.002) and JAK3 (p = 0.02) mutations in NK-LL as compared to AML. As compared to T-ALL, NK-LL cases showed a higher number of total mutations (p = 0.04) and significantly more frequent ETV6 mutations (p = 0.004). Clinical outcome data showed differences in overall survival between all four groups (p = 0.0175), but no difference in event free survival (p = 0.246). In this largest study to date, we find that that NK-LL shows clinical presentation, immunophenotypic and molecular characteristics distinct from AUL, T-ALL, and AML. Our findings suggest NK-LL is a distinct acute leukemia entity and should be considered in the clinical diagnosis of acute leukemias of ambiguous lineage.

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.

Development and validation of an immunoassay for quantification of NCAM-1 in human plasma

BACKGROUND

Neural Cell Adhesion Molecule 1 (NCAM-1), a multifunctional member of the immunoglobulin superfamily, is expressed on the surface of neurons, glia, skeletal muscle, and natural killer cells. NCAM-1 has been implicated as having a role in cell-cell adhesion, involved in development of the nervous system, and for cells involved in the expansion of T cells and dendritic cells which play an important role in immune surveillance. Sensitive and specific methods to quantify non-surface bound NCAM-1 are not available.

METHOD

A sandwich ligand binding assay was developed for quantification of NCAM-1 in plasma and validated using an electro-chemiluminescent (ECL) technology.

RESULTS

The data presented here demonstrated that the validated method met all prespecified criteria for precision, linearity, and accuracy in the range of 62.5 ng/mL to 4000.0 ng/mL, the range believed to be most relevant for plasma. The bioanalytical validation of the assay established the inter-assay coefficient of variation <8 % for calibration points, <2 % for high quality control (HQC), <8 % for medium quality control (MQC) and <19 % for low quality control (LQC) samples. Purified NCAM-1 spike-recovery experiment in plasma was used to determine assay accuracy; nominal concentrations (%) of NCAM-1 ranged from 91 % to 112 % for high and low spike level, respectively. Assay performance was subsequently evaluated for parallelism, selectivity, interference, and stability.

CONCLUSION

NCAM-1 assay has been developed and validated in human plasma and met all assay validation parameters pre-determined during development. Clinical testing of human plasma samples indicated that NCAM-1 does not seem to be influenced by age and was slightly influenced by gender. NCAM-1 assay has potential to be used as a biomarker assay once the assay is subjected to appropriate clinical assessment and diagnostic thresholds are established.

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.

Precursor B-lineage acute lymphoblastic leukemia patients with aberrant natural killer cell and T cell - lineage antigen expression: experience from a tertiary cancer care center

Introduction

Flow cytometric immunophenotyping (FCI) plays a major role in diagnosing hematologic malignancies. In patients diagnosed with precursor B-lineage acute lymphoblastic leukemia (B-ALL), expression of certain non-lineage/cross lineage antigens is of prognostic and cytogenetic relevance. There is a paucity of studies that have comprehensively analyzed the clinical and laboratory profiles of B-ALL patients showing aberrant T/natural killer (NK) cell antigen expression.

Materials and methods

This is a prospective study where 152 consecutive B-ALL patients were analyzed for aberrant expression of T/NK cell antigens (CD1a, CD5, CD4, CD7, CD8 and CD56) by FCI. The clinical and laboratory profile of these T/NK-cell antigen-expressing B-ALL patients was statistically analyzed against conventional B-ALL patients.

Results

In our B-ALL cohort, CD5, CD7 and CD56 expression were observed in one, six and nine patients, respectively. CD56-expressing B-ALL patients were predominantly children (89%) and presented as standard clinical risk (p = 0.010) disease with frequent ETV6-RUNX1 fusion (p = 0.021) positivity. On the contrary, CD7-expressing B-ALL patients were adolescent-young adult/adult-age skewed (83%) and had an adverse cytogenetic profile (p = 0.001), especially for the frequent presence of BCR-ABL1 fusion (p = 0.004) and KMT2A rearrangement (p = 0.045). CD7-expressing B-ALL patients had inferior event-free survival (p = 0.040) than their CD56-expressing counterparts, but there was no significant difference in the overall survival (p = 0.317).

Conclusion

In comparison to conventional B-ALL patients, there are significant differences in the age, cytogenetic profile and event-free survival of T/NK-cell antigen-expressing B-ALL patients.

An activating mutation of the NSD2 histone methyltransferase drives oncogenic reprogramming in acute lymphocytic leukemia

NSD2, a histone methyltransferase specific for methylation of histone 3 lysine 36 (H3K36), exhibits a glutamic acid to lysine mutation at residue 1099 (E1099K) in childhood acute lymphocytic leukemia (ALL), and cells harboring this mutation can become the predominant clone in relapsing disease. We studied the effects of this mutant enzyme in silico, in vitro, and in vivo using gene edited cell lines. The E1099K mutation altered enzyme/substrate binding and enhanced the rate of H3K36 methylation. As a result, cell lines harboring E1099K exhibit increased H3K36 dimethylation and reduced H3K27 trimethylation, particularly on nucleosomes containing histone H3.1. Mutant NSD2 cells exhibit reduced apoptosis and enhanced proliferation, clonogenicity, adhesion, and migration. In mouse xenografts, mutant NSD2 cells are more lethal and brain invasive than wildtype cells. Transcriptional profiling demonstrates that mutant NSD2 aberrantly activates factors commonly associated with neural and stromal lineages in addition to signaling and adhesion genes. Identification of these pathways provides new avenues for therapeutic interventions in NSD2 dysregulated malignancies.

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.

Prognostic impact of CD200 and CD56 expression in pediatric B-cell acute lymphoblastic leukemia patients

This study aimed to determine the prognostic impact of CD200 and CD56 expression in pediatric B cell acute lymphoblastic leukemia (B-ALL) patients, both of which have been implicated in immune tolerance and previously suggested as independent risk factors. CD200 has a central role in immune tolerance that protects stem cells and other critical tissues from immune damage. The expression of CD200/CD56 in leukemic blasts were assessed in leukemic blasts before chemotherapy in 43 bone marrow (BM) and/or peripheral blood (PB) samples by flow cytometry. Twenty eight of 43 B-ALL cases (65%) showed CD200 positive expression, 5 of 43 cases (11.6%) showed CD56 expression, and only 2 patients (4.7%) expressed both CD200 and CD56. Patients with CD200⁺ and CD56⁺ were significantly associated with lower platelet count; less tendency for induction of remission response as compared to negative ones (p = .01 for both). The overall survival (OS) and DFS were significantly shorter in CD200⁺ and CD56⁺ cases as compared to those with CD200^- and CD56^- expression. In conclusion, CD200 and/or CD56 positive expression in B-ALL at diagnosis suggest a poor prognosis and may be associated with biological aggressiveness.

Ocular manifestation in myeloid/NK cell precursor acute leukemia: a case report. Diagnosed by flow cytometry and PCR from aqueous humor

BACKGROUND

Myeloid/NK cell precursor acute leukemia (MNKL) is a rare type of leukemia, and ocular complications have not previously been reported. We now report a patient with MNKL who developed intraocular infiltrates during follow-up.

METHODS AND RESULTS

A 13-year-old boy diagnosed with MNKL developed left eye pain 3 months after starting treatment. Examination of the left eye revealed a visual acuity of counting fingers at 20 cm, ciliary hyperemia, small corneal keratic precipitates, hypopyon, grade 4 vitreous opacities, and an obscured fundus. The differential diagnosis was between an opportunistic infection associated with immunodeficiency and an intraocular leukemic cell infiltrate. Therefore, a sample of aqueous humor was aspirated. Multiplex PCR/broad-range PCR of the aqueous humor was below detection limits for viruses, bacteria, and fungi. Flow cytometry (FCM) detected NK-related CD56-positive cells, thus leading to a diagnosis of ocular infiltrates due to MNKL. With treatment of the ocular infiltrates by consolidation systemic chemotherapy including intrathecal methotrexate (MTX), there was clearing of the vitreous opacities; and optic disc swelling, retinal hemorrhages, exudates, and protuberant lesions were now seen. With the addition of local radiation therapy to the eye, there was a dramatic treatment response, with regression of the optic disc findings and retinal lesions, and an improved visual acuity of 1.5.

CONCLUSION

We encountered the first case of MNKL in which ocular infiltrates developed during follow-up. Multiplex PCR and FCM of the aqueous humor were useful in rapidly distinguishing leukemic cell infiltrates from an opportunistic infection. This case highlights the usefulness of intrathecal MTX and local radiotherapy in treating ocular infiltrates in patients with MNKL.

Ophthalmic Manifestations of Hematopoietic Malignancy

Purpose. To report the ocular findings in patients with hematopoietic malignancy with optic nerve involvement and abducens nerve palsy. Methods. The medical records of all cases of hematopoietic cancer with ophthalmic involvements seen in the Department of Ophthalmology of the National Center for Global Health and Medicine between 2009 and 2014 were reviewed. Results. Eight patients with hematopoietic cancer with optic nerve invasion or abducens nerve palsy were studied. The primary diseases were 3 cases of multiple myeloma, 1 case of acute lymphocytic leukemia, 1 case of follicular lymphoma, and 3 cases of AIDS-related lymphoma. Six cases had optic nerve invasion, 2 cases had abducens nerve palsy, and 1 case had optic nerve invasion of both eyes. The median visual acuity of eyes with optic nerve invasion was 0.885 logarithm of the minimum angle of resolution (logMAR) units. The final visual acuity of eyes with optic nerve invasion was 1.25 logMAR units, and that of those with sixth-nerve palsy was −0.1 logMAR units. Six cases died during the five-year follow-up period. An ophthalmic involvement in patients with hematopoietic cancer, especially AIDS-related lymphoma, was associated with poor prognosis. Conclusion. Because ophthalmic involvement in patients with hematopoietic malignancy has a poor prognosis, an early diagnosis of the cancers by the ophthalmologic findings by ophthalmologists could improve the prognosis.

Naso-Sinusal T ALL With Aberrant Expression of CD56 Mimicking NK/T Non Hodgkin Lymphoma

T-acute lymphoblastic leukemia (T-ALL) represents 25 % of cases of acute lymphoblastic leukemia (ALL) in adults. The clinical presentation is dominated by a elevated number of white blood cells and in immunophenotype the lymphoblasts are generally Tdt positive and variably express CD1a, CD2, CD3, CD4, CD5, CD7, and CD8. NK/T non Hodgkin lymphoma is presented as a single lesion often ulcerated with torpid evolution affecting the nasal cavity, nasopharynx and/or palate. CD56 expression is while characteristic of NK-cells, and is also expressed on a subset of normal T cells. Its expression in ALL does not exclude the diagnosis and seems to be a prognostic factor of this disease. We report the case of a young woman with nasal cavity tumor which was initially diagnosed as T-cell lymphoma. This diagnosis was finally revised to conclude to T-ALL with CD56 aberrant expression.

CD7 promotes extramedullary involvement of the B-cell acute lymphoblastic leukemia line Tanoue by enhancing integrin β2-dependent cell adhesiveness

Extramedullary involvement (EMI) is a factor that defines prognosis of acute lymphoblastic leukemia; however, the molecular mechanism(s) remain elusive. Here, we show that CD7 promotes EMI of the human B-cell acute lymphoblastic leukemia cell line Tanoue. The Tanoue cell line expressing firefly luciferase, Luc-Tanoue, was transplanted into non-obese diabetic/severe combined immunodeficient mice, and cells infiltrated into the brain were cultured ex vivo. This process was repeated 4 times to obtain the highly invasive line Luc-Tanoue-F4. Comparison of the global gene expression signatures of Luc-Tanoue-F4 and Luc-Tanoue indicated that the CD7 gene showed the largest increase in expression among EMI-related genes in Luc-Tanoue-F4 cells. Overexpression of CD7 in Tanoue enhanced cell invasiveness. Among cell migration, proliferation, adhesion and protease activity, only cell adhesiveness showed enhancement in Luc-Tanoue-F4. Expression of the intracellular domain, but not the extracellular domain, of CD7 enhanced cell adhesiveness. Luc-Tanoue-F4 showed a higher level of integrin β2 expression; overexpression of CD7 induced the expression of integrin β2 in Luc-Tanoue. These results show that CD7 induces integrin β2 and enhances cell adhesiveness and invasiveness in Tanoue cells. This study highlights the role of the CD7/integrin β2 axis as a critical pathway in the process of EMI of human B-cell acute lymphoblastic leukemia.

Breaking and entering into the CNS: clues from solid tumor and nonmalignant models with relevance to hematopoietic malignancies

Various malignancies invade the CNS sanctuary site, accounting for the vast majority of CNS neoplastic foci and contributing to significant morbidity as well as mortality. The blood-brain barrier (BBB) exhibits considerable impermeability to chemotherapeutic agents, severely limiting therapeutic options available for patients developing metastatic CNS involvement, accounting for poor outcomes. The mechanisms by which malignant cells breach the highly exclusive BBB and subsequently survive in this unique anatomical site remain poorly understood, with most of the current knowledge stemming from nonmalignant and solid malignancy models. While solid and hematologic malignancies may face different challenges once within the CNS (e.g., solid tumor parenchymal metastasis compared to masses/nodules/leptomeningeal disease in hematologic malignancies), commonality exists in the process of migrating across the BBB from the circulation. Specifically considering this last point, this review aims to survey the current mechanistic knowledge regarding malignant migration across the BBB, necessarily emphasizing the better studied solid tumor and nonmalignant models with the intention of highlighting both the current knowledge gap and additional work required to effectively consider how hematopoietic malignancies breach the CNS.

The Polo-Like Kinase 1 (PLK1) inhibitor NMS-P937 is effective in a new model of disseminated primary CD56+ acute monoblastic leukaemia

CD56 is expressed in 15-20% of acute myeloid leukaemias (AML) and is associated with extramedullary diffusion, multidrug resistance and poor prognosis. We describe the establishment and characterisation of a novel disseminated model of AML (AML-NS8), generated by injection into mice of leukaemic blasts freshly isolated from a patient with an aggressive CD56(+) monoblastic AML (M5a). The model reproduced typical manifestations of this leukaemia, including presence of extramedullary masses and central nervous system involvement, and the original phenotype, karyotype and genotype of leukaemic cells were retained in vivo. Recently Polo-Like Kinase 1 (PLK1) has emerged as a new candidate drug target in AML. We therefore tested our PLK1 inhibitor NMS-P937 in this model either in the engraftment or in the established disease settings. Both schedules showed good efficacy compared to standard therapies, with a significant increase in median survival time (MST) expecially in the established disease setting (MST = 28, 36, 62 days for vehicle, cytarabine and NMS-P937, respectively). Importantly, we could also demonstrate that NMS-P937 induced specific biomarker modulation in extramedullary tissues. This new in vivo model of CD56(+) AML that recapitulates the human tumour lends support for the therapeutic use of PLK1 inhibitors in AML.

Is acute myeloid leukemia a liquid tumor?

Extramedullary manifestations of acute myeloid leukemia (AML) were described as early as the 19th century. However, the incidence, clinical significance and pathobiology of extramedullary AML remain ill defined. We reviewed case reports, retrospective case series, pilot studies and imaging studies of extramedullary leukemia (EML) to determine its frequency, characteristics, clinical presentation and significance. EML precedes or accompanies development of AML and occurs during or following treatment, even during remission. Although imaging studies are rarely conducted and the true incidence of EML has yet to be verified, authors have reported several estimates based on retrospective and autopsy studies. The incidence of EML in patients with AML of all ages is estimated to be about 9% and EML in children with AML was detected in 40% of patients at diagnosis. The combination of positron emission tomography and computed tomography were the most sensitive and reliable techniques of detecting and monitoring EML. Based on our literature review, the frequency of EML is likely underreported. The well-documented nature of EML in patients with AML suggests that AML can manifest as a solid tumor. The extent to which EML accompanies AML and whether EML is derived from bone marrow are unknown. Furthermore, questions remain regarding the role of the microenvironment, which may or may not facilitate the survival and proliferation of EML, and the implications of these interactions with regard to minimal residual disease, tumor cell quiescence and relapse. Therefore, prospective studies of detection and characterization of EML in patients with AML are warranted.

The expression of CD56 antigen is associated with poor prognosis in patients with acute myeloid leukemia

BACKGROUND

The expression of CD56 is considered a bad prognostic factor for overall survival, lower rates or short complete remission and extramedullary invasion but the results are controversial. The importance of validating new prognostic parameters in acute leukemias was the reason to investigate the CD56 expression in blast cells of patients with acute myeloid leukemia.

METHODS

A cohort of 48 patients treated at Hospital de Clinicas de Porto Alegre and diagnosed with acute myeloid leukemia as classified by the French-American-British group (FAB) criteria using cell morphology, cytochemistry and flow cytometry were evaluated.

RESULTS

Eight cases (16.7%) were CD56 positive without correlation to age or gender. The highest incidence of CD56 positivity was in FAB subtypes M4 and M5. The death rate during induction was not significantly different between patients with and without CD56 expression (62.5% vs. 27.5%; p-value = 0.097). However, patients that expressed CD56 had significantly lower overall survival than those who did not (mean 4.0 months vs. 14.5 months; p-value = 0.03).

CONCLUSIONS

The data suggest that expression of CD56 in acute myeloid leukemia may be indicative of poor prognosis because it is associated with a shorter overall survival. The death rate during induction was not significantly different despite an apparent difference in proportions between groups.

Characterization of novel genomic alterations and therapeutic approaches using acute megakaryoblastic leukemia xenograft models

Acute megakaryoblastic leukemia (AMKL) is a heterogeneous disease generally associated with poor prognosis. Gene expression profiles indicate the existence of distinct molecular subgroups, and several genetic alterations have been characterized in the past years, including the t(1;22)(p13;q13) and the trisomy 21 associated with GATA1 mutations. However, the majority of patients do not present with known mutations, and the limited access to primary patient leukemic cells impedes the efficient development of novel therapeutic strategies. In this study, using a xenotransplantation approach, we have modeled human pediatric AMKL in immunodeficient mice. Analysis of high-throughput RNA sequencing identified recurrent fusion genes defining new molecular subgroups. One subgroup of patients presented with MLL or NUP98 fusion genes leading to up-regulation of the HOX A cluster genes. A novel CBFA2T3-GLIS2 fusion gene resulting from a cryptic inversion of chromosome 16 was identified in another subgroup of 31% of non-Down syndrome AMKL and strongly associated with a gene expression signature of Hedgehog pathway activation. These molecular data provide useful markers for the diagnosis and follow up of patients. Finally, we show that AMKL xenograft models constitute a relevant in vivo preclinical screening platform to validate the efficacy of novel therapies such as Aurora A kinase inhibitors.

EuroFlow antibody panels for standardized n-dimensional flow cytometric immunophenotyping of normal, reactive and malignant leukocytes

Most consensus leukemia & lymphoma antibody panels consist of lists of markers based on expert opinions, but they have not been validated. Here we present the validated EuroFlow 8-color antibody panels for immunophenotyping of hematological malignancies. The single-tube screening panels and multi-tube classification panels fit into the EuroFlow diagnostic algorithm with entries defined by clinical and laboratory parameters. The panels were constructed in 2-7 sequential design-evaluation-redesign rounds, using novel Infinicyt software tools for multivariate data analysis. Two groups of markers are combined in each 8-color tube: (i) backbone markers to identify distinct cell populations in a sample, and (ii) markers for characterization of specific cell populations. In multi-tube panels, the backbone markers were optimally placed at the same fluorochrome position in every tube, to provide identical multidimensional localization of the target cell population(s). The characterization markers were positioned according to the diagnostic utility of the combined markers. Each proposed antibody combination was tested against reference databases of normal and malignant cells from healthy subjects and WHO-based disease entities, respectively. The EuroFlow studies resulted in validated and flexible 8-color antibody panels for multidimensional identification and characterization of normal and aberrant cells, optimally suited for immunophenotypic screening and classification of hematological malignancies.

Flow cytometric detection and quantification of CD56 (neural cell adhesion molecule, NCAM) expression in diffuse large B cell lymphomas and review of the literature

AIM

To report unusual CD56 (neural cell adhesion molecule, NCAM) expression on diffuse large B cell lymphoma (DLBCL).

METHODS AND RESULTS

CD56 expression was first detected and quantified on tissues obtained from five cases of DLBCL by flow cytometry (FC), then confirmed by immunohistochemistry. The CD56 expression pattern was heterogeneous among the cases [the molecular equivalent of soluble fluorochrome (MESF) level ranged from 2214 to 133 466]. All were CD10 and Bcl-6 positive, suggesting their germinal centre origin; one was also CD5 positive. An extranodal presentation occurred in three of five cases.

CONCLUSIONS

CD56 expression in B cell lymphoma is a rare occurrence. FC is able to identify aberrant immunophenotypes that can be useful in the identification and monitoring of B cell lymphoma subtypes. The presence of CD56 reported by the literature on certain DLBCL with extranodal presentation might be related to mechanisms involved in growth and expansion.

Methylation pattern of calcitonin (CALCA) gene in pediatric acute leukemia

Disruption of deoxyribonucleic acid (DNA) methylation patterns has emerged as one of the possible origins of leukemogenesis. Calcitonin (CALCA) gene is a hot-spot for gene hypermethylation in acute leukemias. This study aimed to systematically analyze the methylation status of CALCA gene in pediatric acute leukemia using methylation-specific polymerase chain reaction (MSP) and assess its value as a potential prognostic biomarker. The study population consisted of 70 children divided into; 35 acute myeloblastic leukemia (AML) and 35 acute lymphoblastic leukemia (ALL) patients. CALCA gene was found to be hypermethylated in 54.3% of AML and 65.7% of ALL patients. CALCA hypermethylation was neither correlated to any of the clinicopathologic characteristics of patients, standard prognostic factors nor response to induction therapy (P>0.05). Hypermethylated AML and ALL patients displayed poorer clinical outcome when compared with hypomethylated counterparts as evidenced by high relapse and mortality rates with the occurrence of early relapse (P<0.05). The estimated overall and disease-free survival rates at 2.5-years were significantly shorter for hypermethylated patients in both groups (P<0.01). Our results suggest that CALCA gene methylation pattern is an independent prognostic factor in pediatric acute leukemia that could characterize a group of patients with enhanced risk of relapse and death.

AC133 expression in egyptian children with acute leukemia: impact on treatment response and disease outcome

AC133 antigen is expressed restrictively in the immature subset of the CD34 cells. Hence, it is expected to be a valuable prognostic marker in acute leukemia. Sixty Egyptian children with acute leukemia were enrolled into this prospective study divided into 2 groups: 30 acute myeloblastic leukemia (AML) and 30 acute lymphoblastic leukemia (ALL) patients. Flow cytometric assessment of AC133 expression was performed on CD34 blast cells. AC133 was expressed in 66.7% and 40% of AML and ALL patients, respectively. AC133-positive expression was not associated with any of the studied standard prognostic factors. In AML, 80% of patients with poor clinical outcome (relapse or death) were positive for AC133 expression, whereas, all ALL patients who developed resistance as well as those who displayed poor clinical outcome had AC133-positive expression (P<0.05). Patients with positive AC133 expression had significantly shorter overall and disease-free survival times compared with AC133-negative patients in both ALL (P<0.001) and AML (P<0.05) groups. AC133 expression percentage was a reliable poor prognostic marker in ALL patients (P<0.0001). AC133-positive expression is an independent poor prognostic factor in childhood acute leukemia and could characterize a group of patients with resistance to standard chemotherapy, as well as high incidence of relapse and death.

Specific detection of CD56 (NCAM) isoforms for the identification of aggressive malignant neoplasms with progressive development

Alternative splicing of transcripts from many cancer-associated genes is believed to play a major role in carcinogenesis as well as in tumor progression. Alternative splicing of one such gene, the neural cell adhesion molecule CD56 (NCAM), impacts the progression, inadequate therapeutic response, and reduced total survival of patients who suffer from numerous malignant neoplasms. Although previous investigations have determined that CD56 exists in three major isoforms (CD56(120kD), CD56(140kD), and CD56(180kD)) with individual structural and functional properties, neither the expression profiles nor the functional relevance of these isoforms in malignant tumors have been consistently investigated. Using new quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) strategies and novel CD56 isoform-specific antibodies, CD56(140kD) was shown to be exclusively expressed in a number of highly malignant CD56(+) neoplasms and was associated with the progression of CD56(+) precursor lesions of unclear malignant potential. Moreover, only CD56(140kD) induced antiapoptotic/proliferative pathways and specifically phosphorylated calcium-dependent kinases that are relevant for tumorigenesis. We conclude, therefore, that the specific detection of CD56 isoforms will help to elucidate their individual functions in the pathogenesis and progression of malignant neoplasms and may have a positive impact on the development of CD56-based immunotherapeutic strategies.

CD56 expression in T-cell acute lymphoblastic leukemia is associated with non-thymic phenotype and resistance to induction therapy but no inferior survival after risk-adapted therapy

BACKGROUND

Expression of CD56 has been associated with poor prognosis in acute myeloid leukemia and aggressive lymphoma.

DESIGN AND METHODS

We analyzed the impact of CD56 expression in a cohort of 452 newly diagnosed adult T-cell acute lymphoblastic leukemia (T-ALL) patients; clinical data were available for 306 patients. Treatment was according to the GMALL study protocols 06/99 and 07/03 stipulating stratification into standard (thymic T-ALL) and high risk (pre- and mature T-ALL) groups.

RESULTS

CD56 expression was detected in 63/452 (13.9%) patients. CD56(+) T-ALL were predominantly of non-thymic (pre-T 35%, mature 41%) immunophenotypic subtypes, whereas 53% of the CD56(-) cases were thymic T-ALL (p=0.00002). CD13, CD33, CD34 and HLA-DR were significantly more frequently expressed. A clonal T-cell receptor rearrangement was detected in 22/23 CD56(+) ALL. No major clinical differences were observed at presentation. Treatment of CD56(+) ALL resulted in a lower rate of complete remissions (70% vs. 88%) (p=0.001) and a higher rate of resistant disease (21% vs. 8%) (p=0.004). CD56 expression had no significant influence on overall (48% vs. 59%) and disease free survival (67% vs. 57%) at three years.

CONCLUSIONS

CD56 is expressed on a subset of adult T-ALL with distinct immunophenotypical features and higher resistance to therapy. Most CD56(+) ALL were treated in the high-risk arm of the GMALL study protocols owing to their non-thymic phenotype. Thus after risk adapted treatment a prognostic impact of CD56 expression was not detectable.

Undifferentiated tumor: true identity by immunohistochemistry

CONTEXT

"Undifferentiated tumor" refers to a heterogeneous group of neoplasms with little or no evidence of differentiation on routine light microscopic morphology.

OBJECTIVE

To identify the true identity of undifferentiated tumors by immunohistochemical analysis.

DATA SOURCES

Review of the pertinent literature and the authors' experience.

CONCLUSIONS

For treatment and prognostic evaluation, it is crucial to delineate whether an undifferentiated neoplasm is epithelial, mesenchymal, melanocytic, or hematopoietic in nature. Application of a screening panel to demonstrate the expression of markers of major lineages is fundamental for determination of the broad category of neoplasia. Because poorly differentiated carcinomas and in particular sarcomatoid carcinomas are known to be heterogeneous in their antigen expression, several epithelial markers in combination may be required to establish the carcinomatous nature of tumor. A diagnostic misinterpretation as a consequence of occasional aberrant or unexpected antigen expression is best avoided by using a broad panel that includes both antibodies that are anticipated to be positive and those that are expected to be negative. In this treatise, the immunohistochemical dissection of undifferentiated tumors on the basis of their morphologic features is outlined, supplemented with algorithmic immunohistochemical analysis for each morphologic category of small round cell tumors, carcinomatous tumors, sarcomatous (or sarcoma-like) tumors, and tumors with histologically overlapping features, including hematolymphoid malignancies, melanoma, and sarcomas with epithelioid appearance. The utility of several organ- or tissue-specific markers in the context of undifferentiated tumors is reviewed.

Leukemia and the nervous system

Leukemia affects the central and peripheral nervous system. Neurologic complications are a consequence of direct leukemic infiltration, as occurs with leukemic meningitis, and due to complications of either antileukemic treatment (thrombocytopenic or disseminated intravascular coagulation-related intracranial hemorrhage, steroid myopathy, vinca alkaloid peripheral neuropathy) or immune compromise (Herpes zoster shingles or Aspergillus meningitis).

Establishment of a nude mice model of human monocytic leukemia with CNS and multiorgan extramedullary infiltration

OBJECT

To establish a human monocytic leukemia model with central nervous system infiltration in BALB/c nude mice.

METHODS

BALB/c nu/nu mice, pretreated by splenectomy, cytoxan intraperitoneal injection, and sublethal irradiation, were transplanted intravenously with human monocytic leukemic cell line SHI-1. The leukemic cells engrafted in the mice were traced by RT-PCR, histopathological examination, immunohistochemistry and FCM.

RESULT

After engraftment of SHI-1 cells in SCI-nu/nu mice, multiple organs were involved and green solid neoplasms were formed in some organs. Paralysis was developed in some mice at both of the rear legs. Histopathological examination found that vertebral and skull bone marrow were replaced by leukemic cells. Leukemic cells penetrated to the surface of vertebrae, forming neoplasm, and entering to the subdural space, but seldom involving in the spinal parenchyma. In the brain, leukemic cells filled in the subdural space and pia-arachnoid, covered the surface of cerebrum, cerebellum and along the virchow-robin space on the surface of pia mater, eventually invading into the brain parenchyma.

CONCLUSIONS

SHI-1 cells could engraft in the SCI-nu/nu mice, creating an efficient and reproducible experimental model of central nervous system leukemia (CNSL) and multiorgan infiltration. This experimental model may be useful for studies on the pathogenesis of CNSL.

Extramedullary relapse in acute promyelocytic leukemia treated with all-trans retinoic acid and chemotherapy

We analyzed the incidence, presenting features, risk factors of extramedullary (EM) relapse occurring in acute promyelocytic leukemia (APL) treated with all-trans retinoic acid (ATRA) and chemotherapy by using a competing-risk method. In total, 740/ 806 (92%) patients included in three multicenter trials (APL91, APL93 trials and PETHEMA 96) achieved CR, of whom 169 (23%) relapsed, including 10 EM relapses. Nine relapses involved the central nervous system (CNS) and one the skin, of which two were isolated EM relapse. In patients with EM disease, median WBC count was 26950/mm3 (7700-162000). The 3-year cumulative incidence of EM disease at first relapse was 5.0%. Univariate analysis identified age <45 years (P=0.05), bcr3 PML-RARalpha isoform (P= 0.0003) and high WBC counts (> or = 10,000/ mm3) (P<0.0001) as risk factors for EM relapse. In multivariate analysis, only high WBC count remained significant (P= 0.001). Patients with EM relapse had a poorer outcome since median survival from EM relapse was 6.7 months as compared to 26.3 months for isolated BM relapse (P=0.04). In conclusion, EM relapse in APL occurs more frequently in patients with increased WBC counts (> or = 10,000/mm3) and carries a poor prognosis. Whether CNS prophylaxis should be systematically performed in patients with WBC > or = 10,000/mm3 at diagnosis remains to be established.

Leukemic and lymphomatous meningitis: incidence, prognosis and treatment

Neoplastic meningitis (NM) is a common problem in neuro-oncology occurring in approximately 5% of all patients with cancer. Notwithstanding frequent focal signs and symptoms in NM, NM is a disease affecting the entire neuraxis and therefore staging and treatment need encompass all cerebrospinal fluid (CSF) compartments. Central nervous system (CNS) staging of NM includes contrast enhanced cranial computerized tomography (CE-CT) or magnetic resonance imaging (MR-Gd), contrast enhanced spine magnetic resonance imaging (MR-S) or computerized tomographic myelography (CT-M) and radionuclide CSF flow study (FS). Treatment of NM involves involved-field radiotherapy of bulky or symptomatic disease sites and intra-CSF drug therapy. The inclusion of concomitant systemic therapy may benefit patients with NM and may obviate the need for intra-CSF chemotherapy. At present, intra-CSF drug therapy is confined to three chemotherapeutic agents (i.e. methotrexate, cytosine arabinoside and thio-TEPA) administered by a variety of schedules either by intralumbar or intraventricular drug delivery. Although treatment of NM is palliative with an expected median patient survival of 4 to 6 months, it often affords stabilization and protection from further neurologic deterioration in patients with NM. In patients with leukemia or lymphoma, prophylaxis of the CNS is used (utilizing a combination of high-dose systemic chemotherapy and intra-CSF chemotherapy) for patients at high risk as defined by specific tumor-related laboratory markers. Using such a risk-stratified approach, the late occurrence of CNS relapse has decreased dramatically attesting to the value of CNS prophylaxis.