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ABSTRACT: High-dose chemotherapy combined with autologous stem-cell transplantation (ASCT) is the standard therapy for refractory/relapsed aggressive lymphoma. In the era of rituximab-containing frontline regimens, it is becoming more challenging to salvage patients in this setting, and novel approaches are required. This is a randomized study evaluating the safety and efficacy of standard-dose ibritumomab tiuxetan (Zevalin) combined with high-dose BEAM chemotherapy (Z-BEAM) and ASCT in refractory/relapsed aggressive lymphoma.
Forty-three patients with CD20(+) -aggressive lymphoma were randomized to a treatment arm (Z-BEAM, n = 22) or control arm (BEAM alone, n = 21). Ibritumomab tiuxetan was given at 0.4 mCi/kg on day -14 before ASCT.
Patient characteristics, engraftment kinetics, and toxicity profile were similar between the 2 groups. Two-year progression-free survival (PFS) for all patients was 48% (95% confidence interval, 32%-64%): 59% and 37% after Z-BEAM and BEAM alone, respectively (P = .2). Multivariate analysis identified advanced age (hazard ratio [HR], 8.3; P = .001), high-risk disease (relapse within 12 months of diagnosis and/or secondary International Prognostic Index >2; HR, 2.8; P = .04), positive positron emission tomography-computed tomography pretransplant (HR, 2.4; P = .07), and BEAM alone (HR, 2.8; P = .03) as poor prognostic factors. Intermediate-risk patients with 1 or 2 risk factors had better PFS with Z-BEAM compared with BEAM: 69% and 29%, respectively (P = .07). Two-year overall survival was 91% and 62% after Z-BEAM and BEAM, respectively (P = .05). Similar prognostic factors determined survival. The HR for BEAM alone in the multivariate analysis was 8.1 (P = .01).
Standard-dose ibritumomab tiuxetan combined with BEAM high-dose chemotherapy is safe and possibly more effective than BEAM alone as a conditioning regimen for ASCT in the era of rituximab-containing chemotherapy regimens. Cancer 2012. © 2012 American Cancer Society.
Cancer 01/2012; 118(19):4706-14. · 4.77 Impact Factor
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ABSTRACT: Bone marrow homing and engraftment by clinically transplanted hematopoietic stem and progenitor cells is a complex process that is not fully understood. We report that the pan-leukocyte CD45 phosphatase plays an essential role in trafficking and repopulation of the bone marrow by immature human CD34(+) cells and leukemic cells in transplanted nonobese diabetic severe combined immunodeficient mice. Inhibiting CD45 function by blocking antibodies or a CD45 inhibitor impaired the motility of both normal and leukemic human cells. Blocking CD45 inhibited homing and repopulation by immature human CD34(+) cells as well as homing of primary patient leukemic cells. In addition, CD45 inhibition negatively affected development of hematopoietic progenitors in vitro and their recovery in transplanted recipients in vivo, revealing the central role of CD45 in the regulation of hematopoiesis. Moreover, CD45 blockage induced a hyperadhesive phenotype in immature human progenitor cells as well as in murine leukocytes, leading to their defective adhesion interactions with endothelial cells. This phenotype was further manifested by the ability of CD45 blockage to prevent breakdown of adhesion interactions in the BM, which inhibited murine progenitor mobilization. The substantial effects of a direct CD45 inhibition point at its essential roles in cell trafficking, including murine progenitor cell mobilization and both normal immature and leukemic human hematopoietic cells as well as regulation of hematopoiesis and engraftment potential.
Experimental hematology 09/2011; 39(12):1161-1170.e1. · 3.11 Impact Factor
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Kira Orlovsky,
Alexander Kalinkovich,
Tanya Rozovskaia,
Elias Shezen,
Tomer Itkin,
Hansjuerg Alder,
Hatice Gulcin Ozer,
Letizia Carramusa, Abraham Avigdor,
Stefano Volinia,
Arthur Buchberg,
Alex Mazo,
Orit Kollet,
Corey Largman,
Carlo M Croce,
Tatsuya Nakamura,
Tsvee Lapidot,
Eli Canaani
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ABSTRACT: Rearrangements of the MLL (ALL1) gene are very common in acute infant and therapy-associated leukemias. The rearrangements underlie the generation of MLL fusion proteins acting as potent oncogenes. Several most consistently up-regulated targets of MLL fusions, MEIS1, HOXA7, HOXA9, and HOXA10 are functionally related and have been implicated in other types of leukemias. Each of the four genes was knocked down separately in the human precursor B-cell leukemic line RS4;11 expressing MLL-AF4. The mutant and control cells were compared for engraftment in NOD/SCID mice. Engraftment of all mutants into the bone marrow (BM) was impaired. Although homing was similar, colonization by the knockdown cells was slowed. Initially, both types of cells were confined to the trabecular area; this was followed by a rapid spread of the WT cells to the compact bone area, contrasted with a significantly slower process for the mutants. In vitro and in vivo BrdU incorporation experiments indicated reduced proliferation of the mutant cells. In addition, the CXCR4/SDF-1 axis was hampered, as evidenced by reduced migration toward an SDF-1 gradient and loss of SDF-1-augmented proliferation in culture. The very similar phenotype shared by all mutant lines implies that all four genes are involved and required for expansion of MLL-AF4 associated leukemic cells in mice, and down-regulation of any of them is not compensated by the others.
Proceedings of the National Academy of Sciences 05/2011; 108(19):7956-61. · 9.68 Impact Factor
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Amir Schajnovitz,
Tomer Itkin,
Gabriele,
Alexander Kalinkovich,
Karin Golan,
Aya Ludin,
Dror Cohen,
Ziv Shulman, Abraham Avigdor,
Arnon Nagler,
Orit Kollet,
Rony Seger,
Tsvee Lapidot
Nature Immunology 03/2011; 12(5):391-398. · 26.01 Impact Factor
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Amir Schajnovitz,
Tomer Itkin,
Gabriele D'Uva,
Alexander Kalinkovich,
Karin Golan,
Aya Ludin,
Dror Cohen,
Ziv Shulman, Abraham Avigdor,
Arnon Nagler,
Orit Kollet,
Rony Seger,
Tsvee Lapidot
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ABSTRACT: The chemokine CXCL12 is essential for the function of hematopoietic stem and progenitor cells. Here we report that secretion of functional CXCL12 from human bone marrow stromal cells (BMSCs) was a cell contact-dependent event mediated by connexin-43 (Cx43) and Cx45 gap junctions. Inhibition of connexin gap junctions impaired the secretion of CXCL12 and homing of leukocytes to mouse bone marrow. Purified human CD34(+) progenitor cells did not adhere to noncontacting BMSCs, which led to a much smaller pool of immature cells. Calcium conduction activated signaling by cAMP-protein kinase A (PKA) and induced CXCL12 secretion mediated by the GTPase RalA. Cx43 and Cx45 additionally controlled Cxcl12 transcription by regulating the nuclear localization of the transcription factor Sp1. We suggest that BMSCs form a dynamic syncytium via connexin gap junctions that regulates CXC12 secretion and the homeostasis of hematopoietic stem cells.
Nature Immunology 03/2011; 12(5):391-8. · 26.01 Impact Factor
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Yaron Vagima, Abraham Avigdor,
Polina Goichberg,
Shoham Shivtiel,
Melania Tesio,
Alexander Kalinkovich,
Karin Golan,
Ayelet Dar,
Orit Kollet,
Isabelle Petit,
Orly Perl,
Ester Rosenthal,
Igor Resnick,
Izhar Hardan,
Yechiel N Gellman,
David Naor,
Arnon Nagler,
Tsvee Lapidot
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ABSTRACT: The mechanisms governing hematopoietic progenitor cell mobilization are not fully understood. We report higher membrane type 1-MMP (MT1-MMP) and lower expression of the MT1-MMP inhibitor, reversion-inducing cysteine-rich protein with Kazal motifs (RECK), on isolated circulating human CD34+ progenitor cells compared with immature BM cells. The expression of MT1-MMP correlated with clinical mobilization of CD34+ cells in healthy donors and patients with lymphoid malignancies. Treatment with G-CSF further increased MT1-MMP and decreased RECK expression in human and murine hematopoietic cells in a PI3K/Akt-dependent manner, resulting in elevated MT1-MMP activity. Blocking MT1-MMP function by Abs or siRNAs impaired chemotaxis and homing of G-CSF-mobilized human CD34+ progenitors. The mobilization of immature and maturing human progenitors in chimeric NOD/SCID mice by G-CSF was inhibited by anti-MT1-MMP treatment, while RECK neutralization promoted motility and egress of BM CD34+ cells. BM c-kit+ cells from MT1-MMP-deficient mice also exhibited inferior chemotaxis, reduced homing and engraftment capacities, and impaired G-CSF-induced mobilization in murine chimeras. Membranal CD44 cleavage by MT1-MMP was enhanced following G-CSF treatment, reducing CD34+ cell adhesion. Accordingly, CD44-deficient mice had a higher frequency of circulating progenitors. Our results reveal that the motility, adhesion, homing, and mobilization of human hematopoietic progenitor cells are regulated in a cell-autonomous manner by dynamic and opposite changes in MT1-MMP and RECK expression.
The Journal of clinical investigation 03/2009; 119(3):492-503. · 15.39 Impact Factor
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ABSTRACT: Venous thromboembolism is a well-recognized and relatively frequent complication of malignancy, whereas tumor thrombosis is a rare complication of solid cancers. The correct diagnosis of tumor thrombosis and its differentiation from VTE can alter patient management and prevent unnecessary long-term anticoagulation treatment.
To evaluate the contribution of 18F-fluorodeoxyglucose positron emission tomography/computed tomography to the diagnosis of tumor thrombosis and its differentiation from VTE.
PET/CT scans from 11 patients with suspected tumor thrombosis were retrospectively evaluated. Suspicion arose from positive PET/CT in eight cases, or from findings on contrast-enhanced CT in three patients. Criteria for positivity of PET/CT included increased focal or linear uptake of 18F-FDG in the involved vessel. Findings were categorized as PET/CT positive, or PET/CT negative and compared to contrast-enhanced or ultrasound Doppler, pathology where available, and clinical follow-up.
Eight occult tumor thromboses were identified by PET/CT-positive scans. Underlying pathologies included pancreatic, colorectal, renal cell, and head-neck squamous cell carcinoma, as well as lymphoma (4 patients). Three thrombotic lesions on contrast-enhanced CT were PET/ CT negative, due to VTE (2 patients) and leiomyomatosis. Accuracy of PET/CT to differentiate between tumor thrombosis and benign VTE was 100% in this small study.
Contrast-enhanced CT defines the extent of thrombotic lesions, while the functional information from PET/CT characterizes the lesions. It appears that PET/CT may be helpful in the diagnosis of occult tumor thrombosis and its differentiation from VTE.
The Israel Medical Association journal: IMAJ 03/2009; 11(2):69-73. · 1.02 Impact Factor
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ABSTRACT: Positron emission tomography (PET) with F-18 fluorodeoxyglucose detects active lymphoid tissue during HIV-1 infection, with distinct patterns of lymphoid activation correlating to various stages of disease activity. Patients with HIV-1 are at risk for lymphoma, making the differential diagnosis between benign and malignant lymphadenopathy imperative. This study retrospectively evaluated the role of PET/computed tomography (CT) in differentiating active lymphoma from persistent generalized lymphadenopathy in patients with HIV-1.
Seven patients with HIV-1 underwent PET/CT. Six, with known non-Hodgkin lymphoma underwent a total of 16 PET/CT scans; 5/16 scans were performed for initial staging, and 10/16 for evaluating treatment response and follow-up. One patient was referred for evaluation of lymphadenopathy suspected of being lymphoma. PET/CT findings were compared with concurrent clinical, immunologic, and virological data.
PET/CT accurately depicted the extent of lymphoma in 12/16 patients' scans (75%), yet in 4/16 (25%) scans increased fluorodeoxyglucose uptake was noted in lymph nodes of normal CT appearance (PET+/CT-). Viral loads ranged from 0 to 84,000 copies/mL, CD4 T-cell count ranged from 130 to 474 cells/muL in the group. The highest values of both laboratory parameters were concurrent with the discrepant PET+/CT- scans, seen in 4 scans, in 2 patients. The PET+/CT- findings in both these patients were observed in neck, axillae, mediastinum, spleen, and inguinal regions, and sample biopsies of the PET (+) nodes consequently proved benign findings in both patients. All PET+/CT+ findings correctly indicated lymphoma status, as proven by clinical follow-up.
PET/CT accurately detected lymphoma in patients with HIV-1 and had been used confidently as a management tool in this patient group. In the context of discrepant PET/CT findings, increased viral loads and CD4 levels may imply benign HIV-related lymphadenopathy.
Clinical nuclear medicine 10/2008; 33(9):610-4. · 3.92 Impact Factor
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Yasodha Natkunam,
Pedro Farinha,
Eric D Hsi,
Christine P Hans,
Robert Tibshirani,
Laurie H Sehn,
Joseph M Connors,
Dita Gratzinger,
Manuel Rosado,
Shuchun Zhao,
Brad Pohlman,
Nicholas Wongchaowart,
Martin Bast, Abraham Avigdor,
Ginette Schiby,
Arnon Nagler,
Gerald E Byrne,
Ronald Levy,
Randy D Gascoyne,
Izidore S Lossos
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ABSTRACT: The heterogeneity of diffuse large B-cell lymphoma (DLBCL) has prompted the search for new markers that can accurately separate prognostic risk groups. We previously showed in a multivariate model that LMO2 mRNA was a strong predictor of superior outcome in DLBCL patients. Here, we tested the prognostic impact of LMO2 protein expression in DLBCL patients treated with anthracycline-based chemotherapy with or without rituximab.
DLBCL patients treated with anthracycline-based chemotherapy alone (263 patients) or with the addition of rituximab (80 patients) were studied using immunohistochemistry for LMO2 on tissue microarrays of original biopsies. Staining results were correlated with outcome.
In anthracycline-treated patients, LMO2 protein expression was significantly correlated with improved overall survival (OS) and progression-free survival (PFS) in univariate analyses (OS, P = .018; PFS, P = .010) and was a significant predictor independent of the clinical International Prognostic Index (IPI) in multivariate analysis. Similarly, in patients treated with the combination of anthracycline-containing regimens and rituximab, LMO2 protein expression was also significantly correlated with improved OS and PFS (OS, P = .005; PFS, P = .009) and was a significant predictor independent of the IPI in multivariate analysis.
We conclude that LMO2 protein expression is a prognostic marker in DLBCL patients treated with anthracycline-based regimens alone or in combination with rituximab. After further validation, immunohistologic analysis of LMO2 protein expression may become a practical assay for newly diagnosed DLBCL patients to optimize their clinical management.
Journal of Clinical Oncology 02/2008; 26(3):447-54. · 18.37 Impact Factor
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Dita Gratzinger,
Shuchun Zhao,
Robert J Tibshirani,
Eric D Hsi,
Christine P Hans,
Brad Pohlman,
Martin Bast, Abraham Avigdor,
Ginette Schiby,
Arnon Nagler,
Gerald E Byrne,
Izidore S Lossos,
Yasodha Natkunam
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ABSTRACT: Vascular endothelial growth factor-mediated signaling has at least two potential roles in diffuse large B cell lymphoma: potentiation of angiogenesis, and potentiation of lymphoma cell proliferation and/or survival induced by autocrine vascular endothelial growth factor receptor-mediated signaling. We have recently shown that diffuse large B cell lymphomas expressing high levels of vascular endothelial growth factor protein also express high levels of vascular endothelial growth factor receptor-1 and vascular endothelial growth factor receptor-2. We have now assessed a larger multi-institutional cohort of patients with de novo diffuse large B cell lymphoma treated with anthracycline-based therapy to address whether tumor vascularity, or expression of vascular endothelial growth factor protein and its receptors, contribute to patient outcomes. Our results show that increased tumor vascularity is associated with poor overall survival (P=0.047), and is independent of the international prognostic index. High expression of vascular endothelial growth factor receptor-1 by lymphoma cells by contrast is associated with improved overall survival (P=0.044). The combination of high vascular endothelial growth factor and vascular endothelial growth factor receptor-1 protein expression by lymphoma cells identifies a subgroup of patients with improved overall (P=0.003) and progression-free (P=0.026) survival; these findings are also independent of the international prognostic index. The prognostic significance of overexpression of this ligand-receptor pair suggests that autocrine signaling via vascular endothelial growth factor receptor-1 may represent a survival or proliferation pathway in diffuse large B cell lymphoma. Dependence on autocrine vascular endothelial growth factor receptor-1-mediated signaling may render a subset of diffuse large B-cell lymphomas susceptible to anthracycline-based therapy.
Laboratory Investigation 02/2008; 88(1):38-47. · 3.64 Impact Factor
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Cell Stem Cell 12/2007; 1(5):483-4. · 25.42 Impact Factor
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ABSTRACT: To determine the safety and outcome following standard-dose ibritumomab tiuxetan followed by BEAM high-dose chemotherapy and autologous stem cell transplantation (ASCT) in patients with chemo-refractory aggressive non-Hodgkin's lymphoma.
The study included 23 patients, median age 55 years (range, 35-66) with chemo-refractory lymphoma, either primary refractory (n = 11) or in refractory relapse (n = 12). Rituximab 250 mg/m(2) followed by ibritumomab tiuxetan 0.4 mCi/kg were given on day -14 and high-dose BEAM chemotherapy started on day -6.
All patients engrafted. Twenty-one patients are evaluable for response; 11 achieved CR, 9 achieved PR, 5 of whom converted to CR with additional radiation therapy (overall CR rate 76%). With a median follow-up of 17 months (range, 4-27) 16 patients are alive and 12 are progression-free. The estimated 2-year overall and progression-free survival are 67% (95% CI, 46-87%) and 52% (95% CI, 31-72%), respectively. The day-100 rate of treatment-related mortality was 9% (95% CI, 2-33%) and the 2-year cumulative incidence of relapse was 31% (95% CI, 17-57%). Extensive prior therapy (>3 lines), high LDH and IPI score at ASCT, bulky disease, and progression during last chemotherapy were risk factors for reduced survival.
Ibritumomab tiuxetan-BEAM and ASCT is relatively safe and may improve outcome in patients with refractory lymphoma. Although excess nonrelapse mortality can not be ruled out, relapse rate was relatively low, resulting in improved outcome. Standard-risk patients with chemo-sensitive disease may also benefit from ibritumomab tiuxetan-BEAM and ASCT. This hypothesis merits further study in larger-scale prospective randomized studies.
Experimental Hematology 05/2007; 35(4):534-40. · 2.90 Impact Factor
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Alexander Kalinkovich,
Sigal Tavor, Abraham Avigdor,
Joy Kahn,
Alexander Brill,
Isabelle Petit,
Polina Goichberg,
Melania Tesio,
Neta Netzer,
Elizabeth Naparstek,
Izhar Hardan,
Arnon Nagler,
Igor Resnick,
Alexander Tsimanis,
Tsvee Lapidot
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ABSTRACT: Stromal cell-derived factor-1 (SDF-1/CXCL12) and its receptor CXCR4 are implicated in the pathogenesis and prognosis of acute myelogenous leukemia (AML). Cellular microparticles, submicron vesicles shed from the plasma membrane of various cells, are also associated with human pathology. In the present study, we investigated the putative relationships between the SDF-1/CXCR4 axis and microparticles in AML. We detected CXCR4-expressing microparticles (CXCR4(+) microparticles) in the peripheral blood and bone marrow plasma samples of normal donors and newly diagnosed adult AML patients. In samples from AML patients, levels of CXCR4(+) microparticles and total SDF-1 were elevated compared with normal individuals. The majority of CXCR4(+) microparticles in AML patients were CD45(+), whereas in normal individuals, they were mostly CD41(+). Importantly, we found a strong correlation between the levels of CXCR4(+) microparticle and WBC count in the peripheral blood and bone marrow plasma obtained from the AML patients. Of interest, levels of functional, noncleaved SDF-1 were reduced in these patients compared with normal individuals and also strongly correlated with the WBC count. Furthermore, our data indicate NH(2)-terminal truncation of the CXCR4 molecule in the microparticles of AML patients. However, such microparticles were capable of transferring the CXCR4 molecule to AML-derived HL-60 cells, enhancing their migration to SDF-1 in vitro and increasing their homing to the bone marrow of irradiated NOD/SCID/beta2m(null) mice. The CXCR4 antagonist AMD3100 reduced these effects. Our findings suggest that functional CXCR4(+) microparticles and SDF-1 are involved in the progression of AML. We propose that their levels are potentially valuable as an additional diagnostic AML variable.
Cancer Research 12/2006; 66(22):11013-20. · 7.86 Impact Factor
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ABSTRACT: The role of the proteolytic enzyme elastase in motility and proliferation of leukemic human acute myeloblastic leukemia (AML) cells is currently unknown. We report a correlation between abnormally high levels of elastase in the blood of AML patients and the number of leukemic blast cells in the circulation. In AML cells, we observed expression of cell-surface elastase, which was regulated by the chemokine stromal cell-derived factor-1 (SDF-1). In vitro inhibition of elastase prevented SDF-1-induced cell polarization, podia formation, and reduced migration of human AML cells as well as their adhesion. Elastase inhibition also significantly impaired in vivo homing of most human AML cells to the bone marrow (BM) of nonobese diabetic-severe combined immunodeficient (NOD/SCID)/beta-2 microglobulin knock-out (B2m null) mice that underwent transplantation. Moreover, in vitro proliferation of AML cells was elastase dependent. In contrast, treatment with elastase inhibitor enhanced the proliferation rate of human cord blood CD34+ cells, including primitive CD34+/CD38- cells, and their in vivo homing. Finally, NOD/SCID mice previously engrafted with human AML cells and treated with elastase inhibitor had significantly reduced egress of leukemic cells into the circulation. Taken together, our data demonstrate that human AML cells constitutively secrete and express SDF-1-dependent cell-surface elastase, which regulates their migration and proliferation.
Blood 10/2005; 106(6):2120-7. · 9.90 Impact Factor
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ABSTRACT: The Ph1 chromosome has rarely been reported in T-lineage acute lymphoblastic leukemia (T-ALL), and the clinical relevance of this translocation in T-ALL is currently unknown. In chronic myelogenous leukemia (CML) some data indicate derivation of T-cells from the leukemic clone and only a few cases of T-derived blastic crisis have been reported and quite often disputed. Particularly in cases identified initially in blastic crisis it may be difficult to distinguish those from Ph1-positive T-ALL. We herein report 2 patients who presented with a clinical picture of Ph1-positive T-ALL and who raised a differential diagnosis from T-cell blastic crisis of CML. We review the literature and suggest clinical and laboratory features that can help in the diagnosis. According to our literature review, 23 cases of Ph1-positive T-ALL and 44 cases of T-cell blastic crisis of CML, including ours, were reported. Some major differences between the two entities could help in establishing a diagnosis of Ph1-positive T-cell blastic crisis of CML vs. Ph1-positive T-ALL: Male sex and younger age was more predominant in T-ALL. While in most cases of CML blastic crisis there was a history of CML there was no such history in the T-ALL cases. Medullary involvement with lymphoblastic leukemia was present in all cases of T-ALL but only in about half of the cases of CML blastic crisis. None of the CML-blastic crisis cases tested by RT-PCR showed the minor breakpoint transcript, while 2 cases with T-ALL had the minor breakpoint transcript and 1 had both transcripts. Combined morphologic and FISH analysis can help to distinguish between the two entities and was applied in one of our cases. Although both entities carry a severe prognosis, differentiating between them might have clinical relevance, especially in the imatinib era.
Acta Haematologica 02/2005; 113(3):181-9. · 1.35 Impact Factor
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ABSTRACT: Thrombotic microangiopathy (TMA) is one of the most severe complications of stem cell transplantation (SCT). Endothelial cell injury caused by the toxic effects of high-dose chemoradiotherapy is likely the primary event in pathogenesis. The incidence, clinical settings, and risk factors for TMA in the era of nonmyeloablative conditioning have not been well defined. The data on 147 consecutive SCTs in a single center were collected, and patients with TMA were identified. Patient characteristics, response to therapy, and outcome were recorded, and risk factors were determined. TMA occurred in 22 of 147 transplantations, with a projected incidence of 20% +/- 4%. TMA occurred in 3 clinical settings: classic multifactorial TMA, TMA associated with severe hepatic graft-versus-host disease (GVHD), and TMA associated with second SCT, with a projected incidence of 8% +/- 3%, 73% +/- 14%, and 70% +/- 16% of patients at risk, respectively. TMA occurred after 23% +/- 6% of nonmyeloablative and 16% +/- 5% of myeloablative conditioning regimens (not significant). Univariate analysis determined SCT from unrelated donors, SCT during advanced or active disease, second SCT within 6 months of a prior SCT, and acute GVHD as risk factors for TMA. The last 2 factors remained significant in a multivariate model. Thirty-two percent of patients responded to therapy. The peri-TMA mortality rate was 68% +/- 10%. Six patients had diffuse alveolar hemorrhage complicating TMA. SCT-associated TMA is a relatively common complication with unsatisfactory therapy and grim prognosis. Fludarabine-based nonmyeloablative conditioning does not confer a lesser risk for TMA. This observation may relate to the selective use of these regimens in elderly and heavily pretreated patients or to the lack of reduction of GVHD with these regimens, and fludarabine itself may be involved in causing endothelial damage. Further exploration of novel preventive and therapeutic measurements is required in high-risk settings.
Biology of Blood and Marrow Transplantation 08/2004; 10(7):484-93. · 3.87 Impact Factor
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Sigal Tavor,
Isabelle Petit,
Svetlana Porozov, Abraham Avigdor,
Ayelet Dar,
Leonor Leider-Trejo,
Noga Shemtov,
Varda Deutsch,
Ella Naparstek,
Arnon Nagler,
Tsvee Lapidot
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ABSTRACT: The chemokine stromal cell-derived factor-1 (SDF-1) and its receptor CXCR4 participate in the retention of normal hematopoietic stem cells within the bone marrow (BM) and their release into the circulation. Homing and engraftment of human stem cells in immunodeficient mice are dependent on cell surface CXCR4 expression and the production of BM SDF-1, which acts also as a survival factor for both human and murine stem cells. However, the role of SDF-1/CXCR4 interactions in the control of human acute myelogenous leukemia (AML) cell trafficking and disease progression is poorly understood. In this study, we report that although some AML cells do not express surface CXCR4, all AML cells tested express internal CXCR4 and SDF-1. Culture of AML cells with SDF-1 promoted their survival, whereas addition of neutralizing CXCR4 antibodies, SDF-1 antibodies, or AMD3100 significantly decreased it. Pretreatment of primary human AML cells with neutralizing CXCR4 antibodies blocked their homing into the BM and spleen of transplanted NOD/SCID/B2m(null) mice. Furthermore, weekly administrations of antihuman CXCR4 to mice previously engrafted with primary AML cells led to a dramatic decrease in the levels of human AML cells in the BM, blood, and spleen in a dose- and time-dependent manner. Interestingly, the same treatment did not affect significantly the levels of normal human progenitors engrafted into NOD/SCID mice. Taken together, our findings demonstrated the importance of the SDF-1/CXCR4 axis in the regulation of in vivo motility and development of human AML stem cells and identified CXCR4 neutralization as a potential treatment for AML.
Cancer Research 05/2004; 64(8):2817-24. · 7.86 Impact Factor
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Abraham Avigdor,
Polina Goichberg,
Shoham Shivtiel,
Ayelet Dar,
Amnon Peled,
Sarit Samira,
Orit Kollet,
Rami Hershkoviz,
Ronen Alon,
Izhar Hardan,
Herzl Ben-Hur,
David Naor,
Arnon Nagler,
Tsvee Lapidot
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ABSTRACT: Trafficking of human CD34+ stem/progenitor cells (HSCs/HPCs) is regulated by chemokines, cytokines, proteolytic enzymes, and adhesion molecules. We report that the adhesion receptor CD44 and its major ligand, hyaluronic acid (HA), are essential for homing into the bone marrow (BM) and spleen of nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice and engraftment by human HSCs. Homing was blocked by anti-CD44 monoclonal antibodies (mAbs) or by soluble HA, and it was significantly impaired after intravenous injection of hyaluronidase. Furthermore, stromal cell-derived factor-1 (SDF-1) was found to be a rapid and potent stimulator of progenitor adhesion to immobilized HA, leading to formation of actin-containing protrusions with CD44 located at their tips. HPCs migrating on HA toward a gradient of SDF-1 acquired spread and polarized morphology with CD44 concentrating at the pseudopodia at the leading edge. These morphologic alterations were not observed when the progenitors were first exposed to anti-CD44 mAbs, demonstrating a crosstalk between CD44 and CXCR4 signaling. Unexpectedly, we found that HA is expressed on human BM sinusoidal endothelium and endosteum, the regions where SDF-1 is also abundant. Taken together, our data suggest a key role for CD44 and HA in SDF-1-dependent transendothelial migration of HSCs/HPCs and their final anchorage within specific niches of the BM.
Blood 05/2004; 103(8):2981-9. · 9.90 Impact Factor
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Nephrology Dialysis Transplantation 04/2004; 19(3):723-6. · 3.40 Impact Factor
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ABSTRACT: Northern blotting confirmed previous results indicating that the mitogen-activated protein kinase (MAPK) phosphatase Pyst2-L was highly expressed in leukocytes obtained from acute myeloid leukemia (AML) patients. High levels of Pyst2-L mRNA were expressed in bone marrow (BM) and peripheral leukocytes from nine AML and acute lymphoblastic leukemia (ALL) patients. BM from healthy individuals expressed very low levels of Pyst2-L. Whereas high levels of Pyst2-L mRNA and protein were detected in several leukemia cell lines, Pyst2-L mRNA was detected neither in 33/34 samples of normal peripheral blood mononuclear cells (PBMC) nor in leukocyte fractions enriched with CD34+ cells. Certain solid tumor and lymphoblastoid cell lines expressed high levels of Pyst2-L mRNA. In view of the association of Pyst2-L to MAPK signaling cascades, we tested if cell activation, a process involving MAPK signaling, influences Pyst2-L expression. Indeed, activation of T cells and endothelial cells increased Pyst2-L in these cells. Furthermore, TPA, a known MAPK activator, induces the expression of both Pyst2-L mRNA as well as the Pyst2-L protein in leukemia cells. This induction was partially inhibited by PD098059, an Mek1/2-specific inhibitor. Based on the results of this and previous studies, we hypothesize that the high levels of Pyst2-L detected in the active state of AML and ALL diseases and in other types of cancer reflect an altered MAPK signaling pathway in such malignant processes. This alteration may be the result of a failed attempt to counter the constitutive activation of MAPK in transformed cells or alternatively, may represent the activated state of such cells.
Oncogene 10/2003; 22(48):7649-60. · 6.37 Impact Factor
