Yair Herishanu

Diagnostic accuracy of PET⁄CT in patients with extranodal marginal zone MALT lymphoma

Background:  18Fluoro‐2‐deoxyglucose (18FDG) positron emission tomography (PET) is widely used for initial staging and follow‐up in patients with malignant lymphoma. While earlier studies suggested a limited role for PET in extranodal marginal zone mucosa‐associated lymphoid tissue (MALT) lymphoma patients due to their non‐FDG avidity, more recent reports have suggested that the issue is controversial. In the present study, we evaluated the diagnostic accuracy of PET integrated with CT (PETCT) in patients with MALT lymphoma and assessed its reliability in clinical staging and monitoring response.

Leukocytosis in obese individuals: possible link in patients with unexplained persistent neutrophilia

Abstract:  Background: Recently, it was shown that fat tissue produces and releases inflammatory cytokines, and that obesity may be regarded as a state of low‐grade inflammation. In this regard, we aimed to establish an association between obesity and persistent leukocytosis. Patients and methods: We present clinical observations of obese subjects primarily referred for further evaluation of leukocytosis without a cause and validated the link between leukocytosis and elevated body mass index (BMI) in a cross‐sectional study. Results: During 1999–2005, 327 patients were referred for further investigation because of persistent leukocytosis. Of these, 15.3% were asymptomatic obese, mostly females, with mild persistent neutrophilia accompanied by elevated acute‐phase reactants. After careful evaluation, no recognized cause for leukocytosis was found other than the fact that the patients were obese. During a mean follow‐up of 45.6 months, the leukocytosis and the elevated acute‐phase reactants persisted and no new causes for leukocytosis were evident. Furthermore, in a cross‐sectional analysis of 3716 non‐smoker subjects, 62 were found to have leukocytosis. Compared with the population with a normal white blood count range, these subjects with leukocytosis had higher BMI, serum C‐reactive protein (CRP) levels, waist circumference, and neutrophil and platelet count (all P < 0.0005). After logistic regression analysis, only BMI was shown to be associated with leukocytosis (P < 0.0005). Conclusions: Obesity is recognized as a possible cause for reactive leukocytosis. Awareness of this ‘obesity‐associated leukocytosis’ may help the clinician to avoid more extensive and unnecessary diagnostic work‐up, particularly in similar obese subjects.

Activation of CD44, a receptor for extracellular matrix components, protects chronic lymphocytic leukemia cells from spontaneous and drug induced apoptosis through MCL-1

Survival of chronic lymphocytic leukemia (CLL) cells in vivo is supported by the tissue microenvironment, which includes components of the extracellular matrix. Interactions between tumor cells and the extracellular matrix are in part mediated by CD44, whose principal ligand is hyaluronic acid. Here, we show that CD44 is more highly expressed on CLL cells of the clinically more progressive immunglobulin heavy chain variable gene (IGHV)-unmutated subtype than on cells of the IGHV-mutated type. Engagement of CD44 activated the phosphatidylinositol 3-kinase (PI3K)/AKT and mitogen activated protein kinase (MAPK)/ERK pathways and increased myeloid cell leukemia sequence 1 (MCL-1) protein expression. Consistent with the induction of these anti-apoptotic mechanisms, CD44 protected CLL cells from spontaneous and fludarabine-induced apoptosis. Obatoclax, an antagonist of MCL-1, blocked the pro-survival effect of CD44. In addition, obatoclax synergized with fludarabine to induce apoptosis of CLL cells. In conclusion, components of the extracellular matrix may provide survival signals to CLL cells through engagement of CD44. Inhibition of MCL-1 is a promising strategy to reduce the anti-apoptotic effect of the microenvironment on CLL cells.

Biology of Chronic Lymphocytic Leukemia in Different Microenvironments: Clinical and Therapeutic Implications

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of mature monoclonal B cells in peripheral blood, bone marrow, spleen, and lymph nodes. The trafficking, survival, and proliferation of CLL cells is tightly regulated by the surrounding tissue microenvironment and is mediated by antigenic stimulation, close interaction with various accessory cells and exposure to different cytokines, chemokines, and extracellular matrix components. In the last decade there have been major advances in the understanding of the reciprocal interactions between CLL cells and the various microenvironmental compartments. This article discusses the role of the microenvironment in the context of efforts to develop novel therapeutics that target the biology of CLL.

Enoxaparin can be used safely in patients with severe thrombocytopenia due to intensive chemotherapy regimens.

Treatment with intensive chemotherapy regimens is frequently complicated by severe thrombocytopenia. During the period of severe thrombocytopenia, anticoagulant treatment is not uncommonly indicated for thromboembolic events or thromboprophylaxis in these patients. We report 10 hematological patients treated with intensive chemotherapy protocols that were anticoagulated with enoxaparin for catheter related central venous thrombosis and thromboprophylaxis. During the period of severe thrombocytopenia the dosages of enoxaparin were reduced and no major bleeding occurred. Based on our experience we suggest that reduced dosages of low molecular weight heparins may be used relatively safely during transient severe thrombocytopenia.

Predicting infections in high‐risk patients with myelodysplastic syndrome/acute myeloid leukemia treated with azacitidine: Aretrospective multicenter study

Hypomethylating agents have become the standard therapy for patients with high‐risk myelodysplastic syndrome (MDS). In Israel, azacitidine (AZA) is routinely used. Yet, infectious complications are common during AZA therapy. The current study was aimed to evaluate the incidence and predisposing risk factors for infections in AZA‐treated patients. This retrospective study included patients treated with AZA in 18 Israeli medical institutions between 2008 and 2011. Data on 184 patients [157 high‐risk MDS and 27 acute myeloid leukemia (AML)], with a median age of 71.6 (range 29–92) were recorded. Overall, 153 infectious events were reported during 928 treatment cycles (16.5%) administered to 100 patients. One hundred fourteen, 114/153 (75%) events required hospitalization and 30 (19.6%) were fatal. In a univariate analysis, unfavorable cytogenetics, low neutrophil, hemoglobin (Hb) and platelet (PLT) counts were found to be associated with infections (24.4% vs. 12.9%, P < 0.0001; 27% vs. 13.5%, P < 0.0001; 20.4% vs. 11%, P < 0.0001 and 29.2% vs. 14.2%, P < 0.0001, respectively). In multivariate analysis, only low Hb level, low PLT count, and unfavorable cytogenetics remained significant. Prior to therapy, poor cytogenetics, PLT count below 20 × 109/L and neutrophil count below 0.5 × 109/L were predictive of the risk of infection during the first two cycles of therapy. In conclusion, patients with unfavorable cytogenetics, presenting with low neutrophil and PLT counts, are susceptible to infections. Evaluation of infection risk should be repeated prior to each cycle. Patients with poor cytogenetics in whom AZA is prescribed despite low PLT count are particularly at high risk for infections and infection prophylaxis may be considered. Am. J. Hematol. 88:130–134, 2013.

Quantitative flow cytometry of ZAP-70 levels in chronic lymphocytic leukemia using molecules of equivalent soluble fluorochrome.

ZAP‐70 has emerged as a potential pivotal prognostic marker for patients with chronic lymphocytic leukemia (CLL), which could replace immunoglobulin heavy chain mutation status. Although several flow cytometry assays have been described for assessing ZAP‐70 in CLL, certain technical and scientific issues remain unsolved, which have prevented results of this crucial test from being reported, even in the best routine flow cytometry laboratories. In this report, we aimed to solve some of these issues by providing a computerized quantitative flow cytometric assay for ZAP‐70 within the entire CLL population, which would be easy to perform and enable standardization between laboratories.

The Cytokine Midkine and Its Receptor RPTPζ Regulate B Cell Survival in a Pathway Induced by CD74

Lasting B cell persistence depends on survival signals that are transduced by cell surface receptors. In this study, we describe a novel biological mechanism essential for survival and homeostasis of normal peripheral mature B cells and chronic lymphocytic leukemia cells, regulated by the heparin-binding cytokine, midkine (MK), and its proteoglycan receptor, the receptor-type tyrosine phosphatase ζ (RPTPζ). We demonstrate that MK initiates a signaling cascade leading to B cell survival by binding to RPTPζ. In mice lacking PTPRZ, the proportion and number of the mature B cell population are reduced. Our results emphasize a unique and critical function for MK signaling in the previously described MIF/CD74-induced survival pathway. Stimulation of CD74 with MIF leads to c-Met activation, resulting in elevation of MK expression in both normal mouse splenic B and chronic lymphocytic leukemia cells. Our results indicate that MK and RPTPζ are important regulators of the B cell repertoire. These findings could pave the way toward understanding the mechanisms shaping B cell survival and suggest novel therapeutic strategies based on the blockade of the MK/RPTPζ-dependent survival pathway.

T-cell ZAP-70 overexpression in chronic lymphocytic leukemia (CLL) correlates with CLL cell ZAP-70 levels, clinical stage and disease progression

T-cell ZAP-70 overexpression in chronic lymphocytic leukemia (CLL) correlates with CLL cell ZAP-70 levels, clinical stage and disease progression

Therapeutic targeting of CD19 in hematological malignancies: past, present, future and beyond

Abstract During the past few decades, CD19 has been at the center of various scientific/translational endeavors to develop targeted therapeutics against B-cell malignancies. Due to the expression pattern of CD19 throughout the B-cell lineage, and on most B-cell malignancies, it became a preferred target for the development of experimental therapeutic agents during the first years of the monoclonal antibodies era. Successful preclinical experiments led to the first generation of clinical trials, based predominantly on toxin/anti-CD19 murine immunoconjugates. These, however, mostly failed due to poor biochemical design of the reagents, and the generation of human anti-murine antibodies. Modern anti-CD19 reagents are based on humanized anti-CD19 antibodies designed to attract components of the immune system, predominantly T-cells, to eliminate CD19+ target cells. These include, for example, modified anti-CD19 antibodies, and bispecific anti-CD19/CD3 antibodies. One of the most attractive approaches to target malignant B-cells is based on the introduction of chimeric antigen receptors (CARs) into patient derived T-cells. CARs are composed of extracellular recognition sequences derived from anti-CD19 antibodies, and intracellular signaling components that can foster T-cell activation. The novel anti-B-cell therapeutics have shown promising clinical effects against various B-cell malignancies, including acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL), although expected side effects (e.g. significant immunosuppression) were also recorded. These novel successful anti-CD19 agents may have the potential to be used in other fields, such as autoimmunity.