Increased bone marrow angiogenesis in B cell chronic lymphocytic leukemia

Fluorescent-labeled DNA probes applied to novel biological aspects of B-cell chronic lymphocytic leukemia

Fluorescent-labeled DNA probes were used to study 52 chronic lymphocytic leukemia (B-CLL) patients for (1) disease progression, (2) angiogenesis genes, (3) T-cell leukemia 1 gene (TCL1), (4) immunoglobulin heavy chain variable region (IGHv) and (5) chromosome 6q. Compared to stable disease, more patients with progressive disease had > or =2 anomalies and a high percentage of neoplastic nuclei. Anomalies of genes for basic fibroblast growth factor, interleukin 4, vascular endothelial growth factor or TCL1 were not detected. Deletions in IGHv occurred in 25% of patients and correlated with IGHv gene expression. Probes for 6q23 detected more deletions in 6q than probes for 6q21.

Tumor angiogenesis in the bone marrow of multiple myeloma patients and its alteration by thalidomide treatment

Angiogenesis in solid tumors is important to tumor growth, invasion and metastasis. Recently, it has been suggested that angiogenesis plays a certain role in the development of hematopoietic malignancies, including leukemia and multiple myeloma. We evaluated tumor angiogenesis in the bone marrow (BM) of multiple myeloma (MM) patients by calculating microvessel density (MVD) in needle-biopsy specimens obtained from 51 cases of untreated MM or monoclonal gammopathy of undetermined significance (MGUS). The MVD in the BM of donors for transplantation and patients with non-hematological diseases was calculated as a control. There was an obvious increase in MVD in the BM of MM patients, and the MVD correlated with the grade of myeloma cell invasion of the BM in the untreated MM cases. It was recently reported that thalidomide might be effective for the treatment of MM. We assessed the effect of thalidomide on angiogenesis in BM treatment of 11 patients with refractory MM. The concentration of M-protein in the serum or urine of seven of the 11 patients was reduced by at least 30% after thalidomide treatment, and MVD in the BM decreased in three of these seven cases in response to thalidomide. Increased plasma concentrations of basic fibroblast growth factor (FGF-2) and vascular endothelial growth factor (VEGF) were observed in all 11 cases before thalidomide administration and both levels were reduced after treatment with thalidomide. Augmented angiogenesis in the bone marrow of MM patients was confirmed in the present study. It seems that thalidomide is effective in the treatment of MM through the impairment of angiogenesis by decreasing FGF-2 and VEGF production. This is the first report on pathological evidence in the bone marrow of MM before and after thalidomide treatment, in Japan.

Chronic idiopathic myelofibrosis: independent prognostic importance of bone marrow microvascular density evaluated by CD105 (endoglin) immunostaining

Microvascular density (MVD) is substantially increased in bone marrow biopsies of patients with chronic idiopathic myelofibrosis (CIMF). CD105, a useful molecule for assessing MVD in various malignancies, is preferentially expressed by recently formed microvessels. Increased serum-soluble CD105 in patients with chronic myeloproliferative disorders, including CIMF, was documented. CD105 MVD has not so far been investigated in CIMF: to this end, the results in 55 patients with CIMF and 21 controls were compared with the conventional CD34 immunostaining as well as traditional histological and clinical disease features. The MVD mean values estimated by both CD105 and CD34 were significantly higher in CIMF patients than in controls (P<0.00001). In addition, the proportion of CD105-positive megakaryocytes was significantly higher in CIMF than in controls (P<0.0001). A degree of reticulin fibrosis >2 correlated with increased CD105 MVD (P=0.05). A multivariate analysis confirmed that CD105-positive MVD was an independent adverse prognosticator. This study demonstrates that while MVD, as assessed by both CD34 and CD105 immunostaining, is significantly increased in CIMF, only CD105-determined MVD correlates with the degree of fibrosis and is prognostically relevant. These findings provide a rationale for the investigational use of anti-CD105-targeted drugs in CIMF.

Adaphostin-induced apoptosis in CLL B cells is associated with induction of oxidative stress and exhibits synergy with fludarabine

B-cell chronic lymphocytic leukemia (CLL) is characterized by accumulation of clonal lymphocytes resistant to apoptosis. We evaluated the ability of the investigational antileukemic agent adaphostin to induce apoptosis in CLL B cells and synergize with fludarabine in vitro. Analysis by annexin V/propidium iodide (PI) staining revealed that the concentration of adaphostin required to induce 50% cell death (IC50) at 24 hours was 4.2 microM (range, 1.10-11.25 microM; median, 4.25 microM; n=29) for CLL isolates and more than 10 microM for B and T cells from healthy donors. Immunoblots demonstrated adaphostin induced poly(adenosine diphosphate-ribose) polymerase (PARP) cleavage and cleavage of caspase-3 substrates, suggesting that adaphostin induces apoptosis. Adaphostin increased the level of reactive oxygen species (ROS) within CLL B cells, and the antioxidant N-acetylcysteine blocked both adaphostin-induced ROS generation and apoptosis. Adaphostin also caused a decrease in the level of the antiapoptotic protein Bcl-2. When adaphostin was combined with fludarabine (F-ARA-AMP), a synergistic effect on cell death was observed in all 10 CLL samples. These findings not only indicate that adaphostin induces apoptosis selectively in CLL B cells through a mechanism that involves ROS generation but also demonstrate its ability to augment the effects of fludarabine. Further preclinical development of adaphostin as a novel agent for the treatment of CLL appears warranted.

Effect of antisense VEGF cDNA transfection on the growth of chronic myeloid leukemia K562 cells in vitro and in nude mice

To further elucidate the role of vascular endothelial growth factor (VEGF) in the pathogenesis of chronic myeloid leukemia (CML), we transfected K562 cells with a VEGF(121)cDNA sense vector (S), an antisense (AS) vector or vector (V) alone. The growth of transfected cells was investigated by MTT and colony-formation assays, and apoptosis was measured by flow cytometry (FCM) of Annexin-V-FITC/PI dual labeled cells. Transfected cells were subcutaneously transplanted into nude mice and the microvessel density (MVD) of tumor masses was determined by vWF immunohistochemistry staining. We tested the supernatant of different transfected K562 cells against human bone marrow endothelial cells (BMECs), and examined the synergic effects of antisense VEGF(121)cDNA and IFNalpha or STI571 on the proliferation and apoptosis of K562 cells. We found that K562/AS transfectants exhibited a 49% reduction in VEGF secretion, whereas K562/S transfectants exhibited a 3-fold increase in VEGF secretion, all in comparison to the vector controls. K562 cells transfected with antisense VEGF(121)cDNA showed growth retardation in vitro. In transplanted nude mice in vivo, transfection of implanted cells with antisense VEGF(121)cDNA resulted in decreased tumor MVD, and increased apoptosis in the presence of IFNalpha. Taken together, these results suggest that VEGF may be involved in the pathogenesis of CML through autocrine and paracrine mechanisms, and that anti-VEGF therapy alone or in combination with conventional treatment may be beneficial for CML patients.

Serum angiogenin is not elevated in patients with early B-cell chronic lymphocytic leukemia but is prognostic factor for disease progression

The association between angiogenin and cancer progression and poor outcome in solid tumors has been documented, but its significance in leukemias has not been evaluated. Using an ELISA technique (Quantikine Human Angiogenin Immunoassay; R&D Systems), we measured serum angiogenin levels in 77 previously untreated Binet stage A B-cell chronic lymphocytic leukemia (CLL) patients. No difference in angiogenin serum levels could be found between patients (median: 295 ng/mL; range: 74-1700) and 15 age- and sex-matched healthy controls (median: 264 ng/mL; range: 29-1835) (P = NS; Mann-Whitney test). Increased angiogenin serum level was associated with higher LDH (P = 0.03) and beta2-m (P = 0.007) concentrations. However, angiogenin did not reflect the extent of bone marrow (BM) angiogenesis as evaluated by microvessel area (P = 0.611), circulating levels of vascular endothelial growth factor (VEGF) (P = 0.873) and basic fibroblastic growth factor (FGF-2) (P = 0.421). When the 25 patients with available data were stratified into the four major cytogenetic categories (normal karyotype, 13q as a sole aberration, 12q trisomy, 11q or 17p deletion) and aberrations were compared with angiogenin serum levels, no correlation was found (P = 0.651; Kruskall-Wallis test). A cut-off of angiogenin serum level corresponding to median (i.e. 330 ng/mL) or higher identified later upstaging and longer progression-free survival (PFS). The 5-yr PFS was 51.5% for patients with angiogenin levels lower than median and 85% for patients with higher values [P = 0.03; hazard ratio (HR) = 2.86; 95% CI: 1.08-6.72]. Although in multivariate analysis only Rai substages (P = 0.00001) and peripheral blood lymphocytosis (P = 0.009) retained their prognostic significance, angiogenin could be incorporated into the Rai substages thus leading to the identification of the following risk categories: (i) stage 0 (angionenin >330 ng/mL); (ii) stage 0 (angiogenin <330 ng/mL) + stage I-II (angiogenin >330 ng/mL); and (iii) stage I-II (angiogenin <330 ng/mL). The 40-month PFS were as follows: 85%, 65%, 25% (chi(2) for trend = 6.33; d.f. = 1; P = 0.01). In conclusion, serum angiogenin levels although not increased in comparison with healthy controls, may predict clinical outcome of patients with early CLL and help to refine Rai's stratification.

Prognostic value of bone marrow angiogenesis in patients with multiple myeloma undergoing high-dose therapy

Bone marrow (BM) angiogenesis is increased in multiple myeloma and is an important prognostic factor. However, prior studies were mainly done on patients receiving conventional chemotherapy and there is limited data on its prognostic value in patients undergoing high-dose therapy (HDT) as initial therapy. We studied BM angiogenesis in terms of microvessel density (MVD) in 88 newly diagnosed patients, who were uniformly treated, with 3-4 cycles of induction chemotherapy followed by HDT. We examined if MVD at diagnosis was predictive of response to induction therapy or to subsequent HDT. In addition, we also examined its prognostic value in these patients. The median MVD for primary refractory patients was 28 (range, 2-84) compared to 27 (range, 2-99) for responding patients (P=0.7). The median progression-free survival (PFS) was 21 months for those with high-grade angiogenesis compared to 42 months for those with low-grade angiogenesis, P=0.017. The median overall-survival (OS) from diagnosis was 40 months for those with high-grade angiogenesis and not yet reached, for those with low-grade angiogenesis, P=0.007. BM MVD at the time of initial diagnosis is an important prognostic factor for OS and PFS in patients undergoing autologous transplantation as frontline therapy for myeloma.

Angiogenesis in acute and chronic lymphocytic leukemia

The bone marrow microenvironment plays a crucial role in leukemogenesis. Recent studies suggest that its vascularity changes significantly during this process and that angiogenic factors are of major importance in leukemia. This review summarizes the literature concerning the relationship between angiogenesis and the progression of acute and chronic lymphocytic leukemia. It is becoming increasingly evident that agents which interfere with angiogenesis also block tumor progression and anti-angiogenic management has become a prominent aspect of pre-clinical and clinical assessment. Recent applications of anti-angiogenic agents which interfere with or block leukemia progression are reviewed.

VEGF receptor phosphorylation status and apoptosis is modulated by a green tea component, epigallocatechin-3-gallate (EGCG), in B-cell chronic lymphocytic leukemia

We recently reported that chronic lymphocytic leukemia (CLL) cells synthesize and release vascular endothelial growth factor (VEGF) under normoxic and hypoxic conditions. CLL B cells also express VEGF membrane receptors (VEGF-R1 and VEGF-R2), suggesting that they use VEGF as a survival factor. To assess the mechanism of apoptosis resistance related to VEGF, we determined the impact of VEGF on CLL B cells, and we studied the impact of epigallocatechin-3-gallate (EGCG), a known receptor tyrosine kinase (RTK) inhibitor, on VEGF receptor status and viability of CLL B cells. VEGF165 significantly increased apoptotic resistance of CLL B cells, and immunoblotting revealed that VEGF-R1 and VEGF-R2 are spontaneously phosphorylated on CLL B cells. EGCG significantly increased apoptosis/cell death in 8 of 10 CLL samples measured by annexin V/propidium iodide (PI) staining. The increase in annexin V/PI staining was accompanied by caspase-3 activation and poly-adenosine diphosphate ribose polymerase (PARP) cleavage at low concentrations of EGCG (3 microg/mL). Moreover, EGCG suppressed the proteins B-cell leukemia/lymphoma-2 protein (Bcl-2), X-linked inhibitor of apoptosis protein (XIAP), and myeloid cell leukemia-1 (Mcl-1) in CLL B cells. Finally, EGCG (3-25 microg/mL) suppressed VEGF-R1 and VEGF-R2 phosphorylation, albeit incompletely. Thus, these results suggest that VEGF signaling regulates survival signals in CLL cells and that interruption of this autocrine pathway results in caspase activation and subsequent leukemic cell death.

Current approach to diagnosis and management of chronic lymphocytic leukemia

The care of patients with chronic lymphocytic leukemia (CLL) has changed dramatically during the past decade. This review summarizes the work-up of lymphocytosis and the current diagnostic criteria and management of CLL. Although clinical staging (Rai and Binet) remains the foundation for determining prognosis, 50% of patients with early-stage disease at diagnosis will experience an aggressive course of disease with early progression and premature death due to CLL. New laboratory techniques (CD38, fluorescence in situ hybridization [FISH]) can identify some patients with early-stage CLL at high risk of rapid disease progression. The array of treatment options has expanded in recent years and now includes monoclonal antibodies used alone or in combination with purine nucleoside analogues and alkylating agents, which have culminated in dramatically improved response rates. Supportive care guidelines now include vaccination strategies, surveillance for secondary malignancies, and aggressive management of infectious complications. An early hematology consultation is recommended for all patients at diagnosis to identify and counsel high-risk patients with early-stage disease who may benefit from more frequent follow-up or early treatment as part of a clinical trial.

Effect of thalidomide therapy on bone marrow angiogenesis in multiple myeloma

Bone marrow (BM) angiogenesis is increased in multiple myeloma and is an important prognostic factor for survival. Previous studies have shown that BM angiogenesis does not change following chemotherapy or stem cell transplant. Given its potential antiangiogenic effect, we evaluated if thalidomide therapy would affect the BM microvessel density (MVD). We studied BM angiogenesis in 81 patients with various disease stages treated with thalidomide with or without dexamethasone. MVD was determined as previously described. MVD was compared between pretreatment marrows and those obtained 4-6 months following therapy. The median (range) MVD pretherapy was 28 (2-116) and post-therapy was 15 (3-97). A partial or complete response was seen in 58% of patients, stable disease in 41% and progressive disease in one patient. MVD decreased significantly in responders (median decrease of 12, P<0.001). In contrast, no significant change in MVD was seen in those failing to respond to thalidomide. Unlike the lack of resolution of angiogenesis reported with other therapies, we demonstrate for the first time a significant decrease in microvessels with thalidomide therapy. Although not conclusive, this result lends further support to the hypothesis that angiogenesis is a relevant therapeutic target in myeloma.

Neovascularization of bone marrow in patients with diffuse multiple myeloma

BACKGROUND

The goal of the current study was to assess the correlation between bone marrow histology and contrast enhancement in infiltrative diffuse myeloma.

METHODS

Forty-four patients with homogeneous diffuse infiltration of bone marrow by multiple myeloma were examined using magnetic resonance imaging of the spine. The sequence protocol included T1-weighted spin-echo (pre- and post-gadolinium dimeglumine administration) and short-inversion time inversion recovery sequences. The percent increase in signal after intravenous gadolinium administration was calculated in bone marrow from patients with myeloma and from a control group of 86 patients who did not have bone marrow disease. Grade of infiltration with plasma cells, fat cell content, and hematopoietic marrow content were evaluated via histologic assessment of bone marrow, and microvessel density was evaluated via anti-CD34-positive immunostaining.

RESULTS

Increased microvessel density was observed in association with increasing plasma cell content (Kruskall-Wallis test: P < 0.0001). Contrast enhancement increased in a stepwise manner according to grade of microvessel density (Mann-Whitney U test: P < 0.05 and P < 0.001 for increases from low to intermediate and intermediate to high grade) and was significantly higher in patients with myeloma compared with control patients (Mann-Whitney U test: P < 0.001). A significant correlation also was found between histologic extent of tumor infiltration and contrast enhancement (Mann-Whitney U test: P < 0.0001). The mean level of contrast enhancement was 18% in the control group, 26% in patients with low-grade infiltration, 49% in patients with intermediate-grade infiltration, and 90% in patients with high-grade infiltration. In addition, fat cell content was found to be inversely correlated with contrast enhancement (chi-square test: P < 0.01).

CONCLUSIONS

As a consequence of increased microvessel density, decreased fat cell content, and increased cellularity, the presence of diffuse bone marrow infiltration in patients with multiple myeloma can be verified using gadolinium-enhanced magnetic resonance imaging.

Increased microvascular network in bone marrow of HIV-positive haemophilic patients

OBJECTIVES

Angiogenesis has been associated with the pathogenesis of myelodysplastic syndromes (MDSs). However, less is known about the significance of this process in the bone marrow of HIV-positive patients with myelodysplastic features (MDF).

METHODS

Trephines from 22 HIV-positive haemophilic patients were immunostained for CD34 antigen, and the microvessel density (MVD) was quantitatively evaluated and compared with that of 21 biopsies from patients with primary MDS and with that of 12 control bone marrows with no evidence of marrow disease.

RESULTS

Bone marrow MVD in HIV-positive haemophilic patients was similar to that in patients with MDS; however, both groups revealed significantly higher MVD counts than those of control bone marrows (P=0.002). Mean MVD counts of HIV-positive haemophilic patients were significantly associated with HIV RNA levels (P=0.008). In contrast, no correlation was found between MVD and clinical HIV stage or CD4 counts at the time of biopsy.

CONCLUSIONS

These results suggest a direct involvement of HIV in the pathogenesis of MDF in HIV infection. Elucidation of the mechanisms underlying bone marrow angiogenesis in HIV-positive patients may provide further insights into the pathobiology of AIDS.

Effect of allogeneic stem cell transplantation on bone marrow angiogenesis in chronic myelogenous leukemia

Increased bone marrow angiogenesis is a poor prognostic marker in patients with chronic myelogenous leukemia (CML). Allogeneic stem cell transplantation (ASCT) can be curative for patients with CML. Studies in myeloma have shown persistent increased bone marrow microvessel density (MVD) after autologous transplantation. It is not clear if abnormal bone marrow angiogenesis persists following a curative intervention like allogeneic transplantation. We evaluated MVD from bone marrow samples obtained just prior to and at 3-5 months after ASCT in 24 patients with CML. The median MVD pre-transplant was 14 (4-37), with 11 patients having high-grade angiogenesis and 13 having low grade. The median post transplant MVD was 20 (range 5-36), with 12 patients having high-grade angiogenesis and 12 low grade. The median time between biopsies was 4 months (range 1-6 months). The microvessels in the post transplant bone marrow appeared morphologically different with striking dilatation and sinusoidal appearance compared to the pre-transplant marrow. However, there was no significant change in MVD following transplant (P=0.8, paired t-test). Abnormal bone marrow angiogenesis appears to persist in the bone marrow following ASCT for CML, at least in the short term.

Prognosis at diagnosis: integrating molecular biologic insights into clinical practice for patients with CLL

Heterogeneity in the clinical behavior of patients with chronic lymphocytic leukemia (CLL) makes it difficult for physicians to accurately identify which patients may benefit from an early or more aggressive treatment strategy and to provide patients with relevant prognostic information. Given the potential efficacy of newer therapies and the desire to treat patients at "optimum" times, it is more important than ever to develop sensitive stratification parameters to identify patients with poor prognosis. The evolution of risk stratification models has advanced from clinical staging and use of basic laboratory parameters to include relevant biologic and genetic features. This article will review the dramatic progress in prognostication for CLL and will propose statistical modeling techniques to evaluate the utility of these new measures in predictive models to help determine the optimal combination of markers to improve prognostication for individual patients. This discussion will also elaborate which markers and tools should be used in current clinical practice and evaluated in ongoing clinical trials.

A morphometric study of bone marrow angiogenesis in hairy cell leukaemia with clinicopathological correlations

Bone marrow angiogenesis has recently been implicated in the pathophysiology and course of various haematological malignancies. Little is known, however, about the significance of this phenomenon in hairy cell leukaemia (HCL). We evaluated various morphometric characteristics of microvessels, highlighted by means of anti-CD34 immunohistochemistry, in the bone marrow of 44 patients with typical HCL, before and after treatment with interferon-alpha (IFN-alpha). Overall, bone marrow from 103 HCL patients and 20 controls was examined. Microvessel density (MVD) and several size- and shape-related parameters were quantified in the region of most intense vascularization using image analysis. MVD, size-related parameters and the percentage of branching microvessels were higher in HCL than in controls. Likewise, perimeter counts were higher in partial/non-responders than in complete responders. Achievement of complete response was accompanied by smaller calibre microvessels. IFN-alpha induced a decrease in MVD and branching values in cases with diffuse marrow involvement. In univariate analysis, progression-free survival was adversely affected by MVD, branching and major axis length. Multivariate analysis indicated that MVD/branching independently affected progression-free survival and the likelihood of complete response. Our data suggest that the generation of bone marrow microvessels indicated an increased risk of progression and IFN-alpha treatment failure in HCL. Furthermore, the prognostic significance of angiogenesis requires the concomitant assessment of MVD and the complexity of the microvascular network.

Increased angiogenesis in the bone marrow of HIV-positive patients with myelodysplasia

AIM

Little is known about the significance of angiogenesis in the bone marrow of HIV-positive patients with myelodysplastic features (MDF). However, this process has been associated with the pathogenesis of primary myelodysplastic syndromes (MDS). The aim of the study was to investigate angiogenesis in the bone marrow of HIV-positive patients.

METHODS

Bone marrow biopsies from 28 HIV-positive patients were immunostained for factor VIII and the microvessel density (MVD) was quantitatively evaluated and compared with that of 32 biopsies from patients with primary MDS and to 18 control bone marrows from patients with no evidence of bone marrow disease.

RESULTS

Bone marrow MVD in HIV-positive patients was similar to that of MDS. However, both groups revealed significantly higher MVD counts compared to those of control bone marrows (MDF vs controls P=0.022, MDS vs controls P=0.001).

CONCLUSIONS

Bone marrow from HIV-positive patients with MDF reveals similar microvessel counts compared to those with primary MDS, although both differ significantly from that of control bone marrow. Elucidation of the mechanisms underlying bone marrow angiogenesis in HIV-positive patients, may provide further insights into the pathobiology of AIDS and might be of value for the development of new therapeutic strategies for this disease.

Update in the pathologic features of mature B-cell and T/NK-cell leukemias

Modern diagnosis of mature B- and T-cell leukemias requires integration of morphologic, immunophenotypic, and molecular genetic features. This integrative approach has allowed more precise definitions of specific disease entities. This in turn provides better information for clinicians to select proper therapy and determine prognosis. The characteristic pathologic features of these disorders are reviewed.

Adenovirus-mediated gene therapy with an antiangiogenic fragment of thrombospondin-1 inhibits human leukemia xenograft growth in nude mice

Recent investigations support the idea that angiogenesis is involved in the pathophysiology of leukemia. Within a given microenvironment, the angiogenic response is regulated by a delicate balance of angiogenesis inducers and inhibitors. Thrombospondin-1 (TSP-1) is a multifunctional extracellular glycoprotein showing angiostatic properties in multiple in vitro and in vivo assays. Interestingly, there is also proangiogenic domain in this complex molecule. Development of TSP-1 as an antiangiogenic drug has been hindered by multiplicity of its functional effects, difficulties in its production and its poor pharmacokinetics. The aim of the present study was to establish a recombinant adenovirus (ADV.TSP-1(f)) expressing antiangiogenic fragment of TSP-1 (TSP-1(f)), and to determine the feasibility for use of the adenovirally expressed TSP-1(f) in leukemia gene therapy. The results of this investigation showed that TSP-1(f) was expressed efficiently in adenovirus-transduced human myelogenous leukemia K562 cells. Compared to the controls, although there was almost no effect on proliferation of K562 cells in vitro, adenovirus-mediated TSP-1(f) transduction inhibited the growth of K562 xenografts dramatically. Furthermore, the microvessel density (MVD) was much lower in the ADV.TSP-1(f)-treated tumors compared to the controls. These data support the use of in vivo gene delivery approach to produce antiangiogenic fragment of TSP-1 for leukemia therapy.

Circulating proangiogenic cytokines and angiogenesis inhibitor endostatin in untreated patients with chronic lymphocytic leukemia

The serum concentration of two pro-angiogenic cytokines: basic fibroblast growth factor (bFGF) and transforming growth factor beta1 (TGF-beta1), and anti-angiogenic factor endostatin in the serum of 80 never treated B-cell chronic lymphocytic leukemia (CLL) patients and 27 healthy volunteers was measured using an enzyme linked immunosorbent assay. The serum levels of both bFGF and TGF-beta1 were found to be significantly higher in the CLL group (median 40.5 pg/ml and 38.6 ng/ml respectively) when compared to the control group (median 9.4 pg/ml and 18.9 ng/ml, respectively) (p<0.001). The levels of endostatin were not significantly different in CLL and control groups (median 12.3 ng/ml and 8.4 ng/ml, respectively) (p=0.09). In the group of CLL patients the level of bFGF was significantly higher in patients with progressive disease as compared with patients with stable disease (median 90.5 pg/ml and 40.5 pg/ml respectively) (p<0.001). Patients in Rai stage III and IV also had significantly higher levels of bFGF than patients in Rai stage 0-II (median 100.1 pg/ml and 29.3 pg/ml respectively) (p<0.001). The levels of both TGF-beta1 and endostatin were lower in patients in Rai stage III and IV (median 28.9 ng/ml and 9.1 ng/ml respectively) than in patients in Rai stage 0-II (42.8 ng/ml and 13.1 ng/ml respectively) (p<0.001 and p=0.002 respectively). The level of endostatin was also lower in the group of CLL patients with progressive disease (median 10.0 ng/ml) as compared to patients with stable disease (median 20.5 ng/ml) (p=0.008). In conclusion, the disturbance in the balance between pro- and anti-angiogenic factors may have an important influence on the course of CLL.

Increased serum levels of matrix metalloproteinase-9 predict clinical outcome of patients with early B-cell chronic lymphocytic leukaemia

BACKGROUND AND METHODS

Serum levels of matrix metalloproteinase-9 (MMP-9) which agree with progression in solid and haematological tumours were correlated to the risk of disease progression in 62 patients with early (Binet stage A) B-cell chronic lymphocytic leukaemia (CLL). Sera were taken at diagnosis and tested by an enzyme-linked immunosorbent assay.

RESULTS

MMP-9 levels positively correlated with haemoglobin levels (P = 0.03) and platelet count (P = 0.03). No association was found with main clinico-haematological features representative of tumour mass, such as peripheral blood lymphocytosis, bone marrow histology, Rai substages and beta-2 microglobulin (beta-2m). A cut-off of MMP-9 levels corresponding to 33rd percentile (203 ng/mL) or higher identified earlier upstaging and shorter progression-free survival. MMP-9 was a significant prognostic marker in multivariate analysis and partially independent of Rai substages, which suggests its inclusion into such a staging system to better stratify prognostically Rai stages I and II patients.

CONCLUSIONS

MMP-9 serum levels predict disease behaviour and help to refine the prognosis of stage A CLL patients.

Bone marrow angiogenesis and its correlation with other disease characteristics in multiple myeloma in stage I versus stage II-III

PURPOSE

We studied bone marrow angiogenesis in different stages of multiple myeloma according to the Durie and Salmon classification and its correlations with other disease characteristics.

METHODS

Sixty-five immunohistochemical CD34-stained, paraffin-embedded bone marrow biopsies of multiple myeloma patients and 12 controls were studied. The mean number of microvessels per area in each sample was determined as the microvessel density (MVD). In addition, plasma cell infiltration of the bone marrow, serum beta2-microglobulin, immunoglobulin levels, C-reactive protein, and serum calcium concentration were measured in 22 patients with stage I multiple myeloma and in 43 patients in stage II-III.

RESULTS

In myeloma patients, the bone marrow MVD was significantly higher than in controls (P<0.001). In 43 patients with stage II-III multiple myeloma, MVD was significantly higher than in 22 patients with stage I (median MVD 46 and 21 vessels/mm(2), respectively, P=0.005). Additionally, in stage II-III the bone marrow MVD correlated positively with the bone marrow plasma cell infiltration (r=0.55, P<0.001) and the serum beta2-microglobulin level (r=0.53, P<0.001), while in stage I patients no correlation could be found.

CONCLUSIONS

Angiogenesis is significantly increased in stage II-III myeloma in comparison to stage I. In stages II-III, bone marrow angiogenesis is correlated with plasma cell infiltration and serum beta2-microglobulin levels.

A phase 2 trial of combination low-dose thalidomide and prednisone for the treatment of myelofibrosis with myeloid metaplasia

Single-agent thalidomide (THAL) at "conventional" doses (> 100 mg/d) has been evaluated in myelofibrosis with myeloid metaplasia (MMM) based on its antiangiogenic properties and the prominent neoangiogenesis that occurs in MMM. THAL monotherapy at such doses produces approximately a 20% response rate in anemia but is poorly tolerated (an adverse dropout rate of > 50% in 3 months). To improve efficacy and tolerability, we prospectively treated 21 symptomatic patients (hemoglobin level < 10 g/dL or symptomatic splenomegaly) with MMM with low-dose THAL (50 mg/d) along with a 3-month oral prednisone (PRED) taper (beginning at 0.5 mg/kg/d). THAL-PRED was well tolerated in all enrolled patients, with 20 patients (95%) able to complete 3 months of treatment. An objective clinical response was demonstrated in 13 (62%) patients, all improvements in anemia. Among 10 patients who were dependent on erythrocyte transfusions, 7 (70%) improved and 4 (40%) became transfusion independent. Among 8 patients with thrombocytopenia (platelet count < 100 x 10(9)/L), 6 (75%) experienced a 50% or higher increase in their platelet count. In 4 of 21 patients (19%), spleen size decreased by more than 50%. Responses observed were mostly durable after discontinuation of the PRED. The dose of THAL in this study (50 mg/d) was better tolerated than the higher doses used in previous studies. Adverse events associated with corticosteroid therapy were mild and transient. Clinical responses did not correlate with improvements in either intramedullary fibrosis or angiogenesis. THAL-PRED is well tolerated and preliminarily appears to be a promising drug regimen for treating cytopenias in patients with MMM.

Angiogenesis in hematologic malignancies

Angiogenesis is defined as the formation of new capillaries from preexisting blood vessels and plays an important role in the progression of solid tumors. Recently a similar relationship has been described in several hematologic malignancies. Expression of the angiogenic peptides vascular endothelial growth factor (VEGF) and basic fibroblast growth factor correlates with clinical characteristics in leukemia and non-Hodgkin's-lymphoma and the serum/plasma concentrations serve as predictors of poor prognosis. Increased bone marrow microvessels in multiple myeloma (MM) are correlated with decreased overall survival. Thalidomide which has antiangiogenic effects and direct cytotoxic effects was found to be effective in MM, myelodysplastic syndrome and acute myeloid leukemia (AML). Preliminary data indicate activity of VEGF-tyrosine kinase inhibitors in AML. Clinical research is now aimed at testing antiangiogenic treatment strategies in several hematologic neoplasms as well as identifying the best candidate patients for specific approaches.

Endothelial stimulation by small lymphocytic lymphoma correlates with secreted levels of basic fibroblastic growth factor

Lymph nodes (LN) involved with small lympho- cytic lymphoma (SLL) reportedly contain increased numbers of microvessels that may constitute a therapeutic target in this disease. We investigated the secretion of the angiogenic growth factor, basic fibroblastic growth factor (bFGF), from primary tissue cultures of 15 LN with SLL and 10 reactive LN. bFGF was detected from the resulting conditioned media (CM) in 13/15 SLL samples (mean 92 +/- 30, range 5-420 pg/ml) but was undetectable in CM from all reactive lymph nodes. CM was also used in a 72-h human umbilical vein endothelial cell (HUVEC) proliferation assay. HUVEC proliferation increased in the presence of SLL CM (70 +/- 17%, range -4-194%), proportional to secreted levels of bFGF (R2 = 0.95), and was reversed by depleting bFGF from CM. Previous SLL studies have examined either patient serum samples or paraffin-embedded lymph node tissue sections. This is the first study to examine the secretion of an angiogenic growth factor from primary cultures of lymph node cells. Our results indicate that bFGF is probably the primary mediator responsible for increased angiogenesis in involved nodes. These findings may be pertinent to future investigation into the mechanisms of increased angiogenesis in SLL.

Angiogenesis and anti-angiogenesis in hematological malignancies

Although it is well established that the growth of solid tumors requires vigorous neovascularization, it has been assumed that leukemias and other hematological malignancies do not depend on angiogenesis. However, the role of angiogenesis in growth and survival of neoplastic cells of the hematopoietic system has recently been recognized, and provides a rationale for novel therapeutic approaches to hematological malignancy. This review summarizes the literature concerning the relationship between angiogenesis and disease progression of several hematological malignancies. It is becoming increasingly evident that agents that interfere with blood vessel formation also block tumor progression, and, accordingly, antiangiogenic therapy has gained much interest as a potential adjunct to conventional therapy of many hematological malignancies. Recent successful applications of antiangiogenic agents that interfere or block the progression of hematological malignancies are evaluated in light of recent demonstrations of potent angiogenic activity of several hematopoietic growth factors. A novel finding regarding the role of angiogenesis in hematological malignancies, which accounts for many clinical observations as well as the apparent independence of these tumors on marrow vascularity, is presented. The information presented in this review will facilitate the design of future clinical trials using antiangiogenic agents for the treatment of hematological malignancies and will provide a basis for the design of experiments undertaken to define the mechanisms involved, mechanisms that may shed new light on the pathology of hematological malignancies.

Biological and clinical heterogeneity of B-cell chronic lymphocytic leukemia

B-cell chronic lymphoproliferative disorders have been recognized as a heterogeneous group of neoplastic diseases affecting the lymphoid system. They are frequently characterized by leukemic manifestations with peripheral blood and/or bone marrow involvement. B-cell chronic lymphocytic leukemia (B-CLL), a disease which is now accepted as derived from immunologicallycompetent antigen-activated B-cells, is the most common in the western countries. Although for several decades it was considered as a unique entity, a body of evidences is now emerging indicating the biological heterogeneity of B-CLL. Molecular and immunophenotypic data induce to consider two main subgroups of B-CLL exist at the cellular level: in fact, B-CLL cases can be divided into two categories according to IgV gene mutation status. One group develops from "memory" B-cells after antigenic stimulation in the germinal center of secondary follicles, displays mutated gene IgV and lacks CD38 expression; the second one derives from the so-called "naïve" antigen inexperienced B-cells, does not present IgV gene mutations and displays CD38 surface molecule. The two groups seem to be characterised by different clinical outcomes with the "mutated" group expected to have a more benign course than that arising from a "naïve" B-cell. Thus, the definition of the biological features of these different groups could be of help for clinicians in order to recognize patients needing more intensive therapeutic approaches.

Vascularity, angiogenesis and angiogenic factors in leukemias and myelodysplastic syndromes

Bone marrow microenvironment plays a crucial role inthe leukemogenic process. New studies suggest that the bone marrow vascularity changes significantly in the leukemic process and that angiogenic factors play a major role in leukemia and myelodysplasia. However, hematologic malignancies appear to be particularly vulnerable to the effects of angiogenic factors because most of these factors appear to be secreted by hematopoietic cells, and they may have autocrine and paracrine regulatory effects on the hematopoietic system. The use of angiogenesis inhibitors for the treatment of hematologic malignancies is particularly attractive because it may target not only the environment but also the malignant cells.

Bone marrow angiogenesis in multiple myeloma: effect of therapy

Recent studies have demonstrated that angiogenesis has a role in haematological malignancies, including multiple myeloma. Multiple myeloma is characterized by inevitable relapse after standard or high-dose chemotherapy. To study the effect of chemotherapy on bone marrow angiogenesis in patients with multiple myeloma, we used two methods to evaluate bone marrow angiogenesis in patients with newly diagnosed multiple myeloma, comparing these findings with those from bone marrow obtained after standard chemotherapy. Before therapy, an increased degree of bone marrow angiogenesis and a high bone marrow plasma cell labelling index (PCLI) were predictive of poorer survival. As estimated by microvessel density (MVD), the median survivals for patients with low-grade, intermediate-grade and high-grade angiogenesis were 77, 30 and 14 months respectively. After therapy, the MVD did not change significantly. However, when patients with at least a partial response were considered separately, they showed a decrease in MVD. Post-therapy PCLI was predictive of survival, but post-therapy MVD was not. There was good correlation between angiogenesis estimated by visual grading and that determined by MVD assessment. We conclude that the degree of bone marrow angiogenesis is a prognostic marker in patients with multiple myeloma and does not decrease significantly after therapy.

Immunohistochemical expression of basic fibroblast growth factor, vascular endothelial growth factor, and their receptors in stage IV non-Hodgkin lymphoma

Angiogenesis is increased in hematologic malignancies, including non-Hodgkin lymphoma (NHL). Elevated serum levels of two important angiogenic factors, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), are associated with a poor prognosis. Immunohistochemistry was used to evaluate 27 patients with NHL and bone marrow involvement (17 with low-grade B-cell NHL, including 7 with higher grade transformation; 6 with intermediate-grade B-cell NHL; and 4 with T-cell lymphoma). Among the 17 patients with low-grade B-cell NHL, results for 7 were positive for VEGF stain (41.2%), and results were negative for all other stains for VEGF receptors, bFGF, and bFGF receptors. In the 10 patients with intermediate-grade B-cell NHL and T-cell lymphoma, all VEGF staining was positive (100%), but bFGF staining was only weakly positive in 2. Staining results for seven patients who had low-grade B-cell NHL with higher grade transformation showed that VEGF staining was positive in large lymphoid cells of 5 patients and in small lymphoid cells of one patient. Staining for the receptors VEGFR-1 and VEGFR-2 was positive in large lymphoid cells in four and two cases, respectively. Staining for bFGF was positive in two cases of large lymphoid cells. We concluded that VEGF, but not bFGF, was associated with higher tumor grading of NHL and high-grade transformation of low-grade lymphoma.

Prognostic value of enhanced bone marrow angiogenesis in early B-cell chronic lymphocytic leukemia

Because tumor progression is angiogenesis-dependent, angiogenesis density was investigated by immunohistochemistry and computed image analysis in bone marrow (BM) biopsies of 45 newly diagnosed patients with Binet stage A B-cell chronic lymphocytic leukemia (BCLL) and correlated to upstaging and progression-free survival during a 40-month follow-up period. Their microvessel areas and counts were significantly higher than those of patients with anemia due to iron or vitamin B(12) deficiencies. A cutoff value of 0.90 mm(2) x 10(-2) or greater of the microvessel area identified patients with earlier upstaging and shorter progression-free survival. When the cutoff was applied to the Rai subclassification, both Rai 0 and Rai I-II patients who upstaged and shortened the progression-free survival were classified correctly. Information of this type was not given by the microvessel counts. The cutoff did not correlate with other predictors representative of tumor mass or disease progression. The microvessel area correlated with the expression of angiogenic vascular endothelial growth factor (VEGF) by tumor tissue, and serum levels of VEGF were found to be of prognostic value. A causal relationship between risk of progression and BM angiogenesis in BCLL is suggested. A risk stratification inside Rai is proposed. The prognostic usefulness of BM angiogenesis in patients with BCLL is envisaged.

Vascular endothelial growth factor as a target opportunity in hematological malignancies

Vascular endothelial growth factor (VEGF) is a potent angiogenic peptide with diverse biologic effects. There are seven members of the VEGF family, VEGF-A through VEGF-E, placental growth factor and the newly described, tissue-specific endocrine gland-derived VEGF. VEGF expression is induced by a number of stimuli including hypoxia, activated oncogenes, and inflammatory cytokines while negative regulators include wild type von Hippel-Lindau and p53 tumor suppressor genes. VEGF activity is mediated through interactions with high affinity tyrosine kinase receptors. To date, three have been identified. Interaction with these receptors activates multiple signal pathways leading to the diverse biologic activity of VEGF. Evidence suggests that VEGF is also a survival factor for endothelial cells and perhaps tumor cells. The importance of angiogenic factors such as VEGF, while clearly established in solid tumors, has not been fully elucidated in human hematopoietic neoplasms. Evolving data generally that elevated levels of VEGF confer a poor prognosis to patients with these diseases. The central role of VEGF in angiogenesis coupled with the relatively restricted expression of its receptors, has led to the development of a number of agents to target this system that are currently under clinical investigation.

Increased angiogenesis in bone marrow of children with acute lymphoblastic leukaemia has no prognostic significance

The importance of angiogenesis for the growth and viability of solid tumours has been established. Similarly, prognostic information may be gained from the extent of angiogenesis in these tumours. Haematopoietic malignancies should have equal requirements for angiogenesis and important prognostic information may be derived from quantification of bone marrow angiogenic activity. We retrospectively investigated 82 bone marrow trephine biopsies from 41 children with acute lymphoblastic leukaemia (ALL) at diagnosis and following treatment. Nine normal bone marrow trephines from age-matched children were also analysed as controls. The microvessels were stained immunohistochemically with anti-Factor VIII-related antigen (antivWF) and antithrombomodulin (anti-THR). Angiogenesis was quantified manually by two independent observers and was highly reproducible (Pearson's r = 0.91). Staining with anti-vWF and anti-THR was highly specific for microvessels and thetwo stains closely correlated (r = 0.68). Microvessel densities (MVD) at presentation were significantly increased in the majority of patients in comparison with controls (P < 0.0001) and MVD dropped towards normal in remission (P < 0.0001). Of interest, the difference in total vessel counts between leukaemic and normal/remission marrows was contributed solely by small microvessels. There was no significant difference in MVD at presentation or remission from children in poor prognostic groups or those who subsequently relapsed. Similarly, we could not find an association with age, sex, cytogenetic abnormality or disease phenotype.

Clinical and scientific advances in the Philadelphia-chromosome negative chronic myeloproliferative disorders

The chronic myeloproliferative disorders are clonal hematopoietic stem cell disorders and include chronic myeloid leukemia (CML), polycythemia vera (PV), essential thrombocythemia (ET), and agnogenic myeloid metaplasia (AMM). These diseases are characterized by clonal expansion of the myeloid compartment, increased marrow angiogenesis, and varying risks for blastic transformation. A clear molecular abnormality exists (t(9;22) leading to the fusion of BCR-Abl) only for CML, which led to effective targeted therapy (STI-571). Since no similar pathogenetic mechanism has been discovered for the t(9;22) negative chronic myeloproliferative disorders, their respective diagnosis is currently based on a variety of rather cumbersome diagnostic criteria. Polycythemia vera is distinguished from reactive erythrocytosis through erythropoietin independent growth of erythroid progenitors in vitro, suppressed levels of endogenous erythropoietin, possible overexpression of PRV-1 (polycythemia rubra vera-1), decreased c-Mpl expression on megakaryocytes, as well as overexpression of bcl-xL, and potentially aberrant activity of the Jak-Stat pathway. ET is defined by thrombocytosis and is distinguished from reactive states by decreased megakaryocyte c-Mpl expression, and a propensity for thrombosis. AMM has been associated with a variety of observations including increased concentrations of pro-fibrotic cytokines, increased angiogenesis, and myeloid expansion. AMM is often indistinguishable clinically and prognostically from the advanced phases of other CMPD (specifically post-polycythemic and post-thrombocythemia myeloid metaplasia), all of which are subentities of a diagnosis of myelofibrosis with myeloid metaplasia (MMM). The management of CMPD patients is quite varied given the broad range of disease severity and survival observed. The role of stem cell transplantation is limited by the age and comorbidities encountered in CMPD patients. Since no broadly applicable therapy effects the mortality of the CMPD, management currently focuses on the prevention/palliation of disease morbidity (i.e. vascular complications, pruritus, organomegaly, constitutional symptoms). Palliative strategies which currently focus on non-specific myelosuppresion, will hopefully be soon replaced by targeted therapies as insight into pathogenetic mechanisms of these diseases evolves.

Overexpression of vascular endothelial growth factor (VEGF) and its cellular receptor KDR (VEGFR-2) in the bone marrow of patients with acute myeloid leukemia

Vascular endothelial growth factor (VEGF) and its cellular receptor VEGFR-2 have been implicated as the main endothelial pathway required for tumor neovascularization. However, the importance of the VEGF/VEGFR-2 system for angiogenesis in hematologic malignancies such as AML remains to be elucidated. In 32 patients with newly diagnosed untreated AML, we observed by immunohistochemical analysis of bone marrow biopsies significantly higher levels of VEGF and VEGFR-2 expression than in 10 control patients (P <0.001). In contrast, VEGFR-1 staining levels in AML patients were in the same range as in the controls. Expression of VEGF and VEGFR-2 was significantly higher in patients with a high degree of microvessel density compared to those with a low degree (VEGF: P =0.024; VEGFR-2: P =0.040) and correlated well with bone marrow microvessel density (r(s)=0.566 and 0.609, respectively; P <0.001). Furthermore, in patients who achieved a complete remission following induction chemotherapy VEGFR-2 staining levels decreased into the normal range. In conclusion, our results provide evidence for increased expression of VEGF/VEGFR-2 of leukemic blasts and correlation with angiogenesis in the bone marrow of AML patients. Thus, VEGF/VEGFR-2 might constitute promising targets for antiangiogenic and antileukemic treatment strategies in AML.

The stromal composition of malignant lymphoid aggregates in bone marrow: variations in architecture and phenotype in different B-cell tumours

We present evidence that different B-cell tumours, in bone marrow, have different relationships to stroma. Marrow core biopsies from 46 patients with B-cell tumours were immunostained with antibodies for distinct stromal cells. Cases included follicular lymphoma (FL), chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL), mantle cell lymphoma (MCL), lymphoplasmacytic lymphoma (LPL), and nodal, extranodal and splenic marginal zone lymphoma (NMZL, MALT, SMZL). In normal marrow, low-affinity nerve growth factor receptor (LNGFR) highlighted a fine network of adventitial reticular cells (ARC). The nodular aggregates of CLL/SLL, NMZL, MALT and SMZL were characterized by distortion of the ARC network and downregulation of LNGFR. In contrast, the aggregates of FL, LPL and MCL were composed of linear arrays of ARC in tight association with individual tumour cells. LNFGR+ was upregulated in ARC associated with the aggregates in FL, LPL and focally in MCL. Upregulation of CD35, vascular cell adhesion molecule (VCAM-1) and CD40 on ARC was noted exclusively in FL. Marrow lymphoid aggregates in CLL/SLL, NMZL, MALT and SMZL probably grow by displacing the pre-existing marrow stroma, while FL and LPL maintain a close association with the ARC network. In FL, expression of follicular dendritic cell-associated markers is modulated in pre-existing marrow stromal cells.

Diagnostic and prognostic value of bone marrow angiogenesis and megakaryocyte c-Mpl expression in essential thrombocythemia

The lack of diagnostic certainty in some patients makes it difficult to distinguish between primary and secondary forms of thrombocytosis. To augment current diagnostic studies for thrombocytosis, we retrospectively evaluated clinical records and bone marrow trephine specimens of 183 patients with thrombocytosis-164 with essential thrombocythemia (ET), 19 with reactive thrombocytosis (RT)-for bone marrow angiogenesis, bone marrow megakaryocyte c-Mpl staining, and morphologic evidence of megakaryocyte proliferation. Angiogenesis was increased in patients with ET compared with healthy controls (P <.0001) and patients with RT (P =.006). In addition, an increase in angiogenesis was associated with certain disease features such as splenomegaly (P =.004) and reticulin fibrosis (P =.005). Decreased megakaryocyte c-Mpl staining was observed in a heterogeneous pattern in ET compared with healthy controls (P <.0001) and RT (P <.0001). Histologic stratifying criteria incorporating increased angiogenesis, decreased megakaryocyte c-Mpl expression, and marked megakaryocyte proliferation in the bone marrow was highly sensitive (97%) and specific (95%) for distinguishing ET from RT (P <.0001). However, with the current duration of follow-up available on the patients, none of the histologic features evaluated have yet demonstrated prognostic value for subsequent clinical course, vascular events, or survival.

B-CLL cells are capable of synthesis and secretion of both pro- and anti-angiogenic molecules

Initial work has shown that clonal B cells from B-chronic lymphocytic leukemia (B-CLL) are able to synthesize pro-angiogenic molecules. In this study, our goal was to study the spectrum of angiogenic factors and receptors expressed in the CLL B cell. We used ELISA assays to determine the levels of basic fibroblast growth factors (bFGF), vascular endothelial growth factor (VEGF), endostatin, interferon-alpha (IFN-alpha) and thrombospondin-1 (TSP-1) secreted into culture medium by purified CLL B cells. These data demonstrated that CLL B cells spontaneously secrete a variety of pro- and anti-angiogenic factors, including bFGF (23.9 pg/ml +/- 7.9; mean +/- s.e.m.), VEGF (12.5 pg/ml +/- 2.3) and TSP-1 (1.9 ng/ml +/- 0.3). Out of these three factors, CLL B cells consistently secreted bFGF and TSP-1, while VEGF was expressed in approximately two-thirds of CLL patients. Of interest, hypoxic conditions dramatically upregulated VEGF expression at both the mRNA and protein levels. We also employed ribonuclease protection assays to assay CLL B cell expression of a variety of other angiogenesis-related molecules. These analyses revealed that CLL B cells consistently express mRNA for VEGF receptor 1 (VEGFR1), thrombin receptor, endoglin, and angiopoietin. Further analysis of VEGFR expression by RT-PCR revealed that CLL B cells expressed both VEGFR1 mRNA and VEGFR2 mRNA. In summary, these data collectively indicate that CLL B cells express both pro- and anti-angiogenic molecules and several vascular factor receptors. Because of the co-expression of angiogenic molecules and receptors for some of these molecules, these data suggest that the biology of the leukemic cells may also be directly impacted by angiogenic factors as a result of autocrine pathways of stimulation.

Production of matrix metalloproteinase-9 in early stage B-CLL: suppression by interferons

Besides vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), matrix metalloproteinases (MMPs) play critical roles in angiogenesis, tumor invasion and metastasis. Increased angiogenesis is observed in chronic B lymphocytic leukemia (B-CLL) and published data reported VEGF and bFGF production in this disease. The purpose of this study was to investigate MMP expression in early stage B-CLL. Elevated MMP-9 concentrations were detected by ELISA in the sera of B-CLL patients (median level 250 ng/ml) compared with healthy donors (67 ng/ml) (P < 0.0001), and immunostaining with antibodies against MMP-9 and B cell antigens (CD19, CD23) substantiated the presence of MMP-9 in tumoral B lymphocytes. By using RT-PCR, ELISA and zymography experiments, we confirmed that B-CLL cells expressed and released the pro-form of MMP-9 with Mr 92 kDa (158-1300 pg/ml/10(6) cells/48 h), p-aminophenylmercuric acetate generating a 82 kDa active form. In contrast, the production of MMP-9 by normal counterpart B cells was significantly low (28-169 pg/ml/10(6)cells/48 h). Moreover, B-CLL culture supernatants contained bFGF (median levels 17 pg/ml/10(6) cells/48 h), VEGF (1.4 pg/ml/10(6) cells/48 h) and TNF-alpha (0.2 pg/ml/10(6) cells/48 h). TNF-alpha and VEGF antibodies blocked MMP-9 at the mRNA and protein levels. Interferons (IFNs) type I or type II repressed MMP-9 gelatinolytic activity in a dose and time dependency, and this was reflected by a parallel inhibition of MMP-9 mRNA and protein. IFNs however did not affect the production of bFGF, VEGF and TNF-alpha. Together, our data show that B-CLL lymphocytes synthesize MMP-9 and emphasize the specific inhibitory actions of IFNs on its expression.

Human T-cell lymphotropic virus type 1-transformed cells induce angiogenesis and establish functional gap junctions with endothelial cells

The role of angiogenesis in the growth and metastasis of solid tumors is well established. However, the role of angiogenesis in hematologic malignancies was only recently appreciated. We show that HTLV-I-transformed T cells, but not HTLV-I-negative CD4(+) T cells, secrete biologically active forms of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) and, accordingly, induce angiogenesis in vitro. Furthermore, fresh ATL leukemic cells derived from patients with acute ATL produce VEGF and bFGF transcripts and proteins. The viral transactivator Tax activates the VEGF promoter, linking the induction of angiogenesis to viral gene expression. Angiogenesis is associated with the adhesion of HTLV-I-transformed cells to endothelial cells and gap junction-mediated heterocellular communication between the 2 cell types. Angiogenesis, cell adhesion, and communication likely contribute to the development of adult T-cell leukemia-lymphoma and represent potential therapeutic targets.

Angiogenesis in hematologic malignancies and its clinical implications

Angiogenesis is defined as a neoformation of blood vessels of capillary origin. Hematopoiesis is closely linked with angiogenesis, for they share a common ancestor, the hemangioblast. Although it is well established that growth in solid tumors is dependent on angiogenesis, its role in hematologic malignancies has not yet been clarified. In this review, the direct evidence, ie, increased microvessel density, and the indirect evidence, ie, elevated level of angiogenic factors or overexpression of messenger RNA or protein of angiogenic factors, for and against the role of angiogenesis in the development and progression of hematologic malignancies are presented.

The role of angiogenesis in hematologic malignancies

Several reports have highlighted the biologic relevance of angiogenesis in neoplastic disorders and its potential impact on prognosis. In this review, we focus on recent findings about angiogenesis and angiogenetic factors in hematologic malignancies. We summarize the body of evidence supporting the hypothesis that a common progenitor gives rise to cells of both the endothelial and the hematopoietic lineages, and the current knowledge about the involvement of normal stromal cells in bone marrow angiogenesis. We also discuss the methodological aspects of microvessel count as a measure of tumor angiogenesis. Finally, we describe the current therapeutic role of angiogenesis inhibitors and possible future strategies involving these agents.

A review of angiogenesis and anti-angiogenic therapy in hematologic malignancies

Tumor angiogenesis is currently not only a concept but has also become a rationale for the therapeutic use of both old and new drugs that might affect new blood vessel formation. There is growing evidence that angiogenesis is as important in hematologic malignancies as it is in solid tumors. Both myeloid and lymphoid disorders may be accompanied by a prognostically detrimental increase in bone marrow microvessel density. In this review, we summarize the current literature as well as our own studies regarding bone marrow angiogenesis and the use of anti-angiogenic treatment in hematologic disorders. Background information on pathogenesis and laboratory methods of quantifying bone marrow angiogenesis is also discussed.

Bone marrow angiogenesis in systemic mast cell disease

Mast cells may participate in tumor angiogenesis through the release of angiogenic cytokines from their secretory granules. To gain additional insight into the role of mast cells in bone marrow angiogenesis, we performed a semiquantitative measurement of bone marrow microvessel density in 52 consecutive adult patients with systemic mast cell disease (SMCD). The results were examined for potential correlations with mast cell expression of angiogenic cytokines and with other histologic features of the bone marrow. Standard immunohistochemical methods were used to visualize bone marrow microvessels (CD34 staining) and mast cell expression of transforming growth factor-beta, basic fibroblast growth factor, and their respective receptors. An increase in microvessel density was demonstrated in 32 of the 52 patients (62%) with SMCD, and the degree of bone marrow angiogenesis did not correlate with either the mast cell expression pattern of the study cytokines or the presence (23 patients) or absence (29 patients) of an associated hematologic disorder. In the 29 patients without an associated hematologic disorder, microvessel density was correlated significantly with the presence of an abnormal pattern of hematopoiesis but not with the degree of bone marrow involvement by mast cells. Furthermore, areas occupied by mast cell lesions were often devoid of neovascularization. We conclude that bone marrow angiogenesis characterizes a percentage of patients with SMCD and that the pathogenesis may not necessarily be linked to the mast cells themselves.

Clinicoprognostic implications of increased serum levels of vascular endothelial growth factor and basic fibroblastic growth factor in early B-cell chronic lymphocytic leukaemia

To assess the relative merit of increased serum levels of vascular endothelial growth factor and basic fibroblastic growth factor in predicting the risk of disease progression of patients with early B-cell chronic lymphocytic leukaemia we analyzed 81 Binet stage A patients whose sera were taken at the time of diagnosis and evaluated for the presence of vascular endothelial growth factor and basic fibroblast growth factor using an enzyme-linked immunosorbent assay. Serum levels of vascular endothelial growth factor positively correlated with Rai sub-stages (P=0.03), peripheral blood lymphocytosis (P=0.03), bone marrow histology (P=0.04) and beta2-microglobulin (beta2-m) (P=0.006). When dealing with basic fibroblast growth factor only a correlation with Rai sub-stages (P=0.02) could be found. Different cut-offs set on the basis of a stratification in quartiles, failed to demonstrate any correlation between serum levels of basic fibroblast growth factor and disease progression. In contrast, patients with increased serum levels of vascular endothelial growth factor (above median value, 203 pg ml(-1)) had a three times increased risk of disease progression, although, in multivariate analysis only Rai sub-stages (P=0.0001) and lymphocyte doubling time (P=0.002) retained their prognostic significance. Low levels of vascular endothelial growth factor were indicative of good clinical outcome in the subgroup of patients with either low (P=0.02) or high (P=0.03) beta2-m concentration. Finally, the highest prognostic power was obtained when serum vascular endothelial growth factor and beta2-m were examined in combination. Median of progression-free survival of patients who had both serum vascular endothelial growth factor and beta2-m higher than median value was only 13 months, in contrast median progression-free survival of patients with one marker increased (i.e. above the 50th percentile) was 40 months. Patients with both markers below the median experienced the best clinical outcome (median progression-free survival not reached at 40 months). In conclusion, serum levels of either vascular endothelial growth factor or basic fibroblast growth factor are high in patients with early chronic lymphocytic leukaemia, however, only vascular endothelial growth factor predicts behaviour of disease and helps to refine the prognosis of stage A patients.

The vascular endothelial growth factor (VEGF) signaling pathway: a therapeutic target in patients with hematologic malignancies

Angiogenesis is an important component in the progression and metastasis of solid tumors. We now appreciate that angiogenesis is also critically involved in the pathogenesis of hematologic malignancies. Current data suggest important prognostic and therapeutic implications of angiogenesis in a variety of malignancies of the hematopoietic system, including acute and chronic leukemias, myeloproliferative diseases, multiple myeloma, non-Hodgkin's lymphomas, and Hodgkin's disease. Vascular endothelial growth factor (VEGF) is a major angiogenic factor that regulates multiple endothelial cell functions, including mitogenesis. Cellular and circulating levels of VEGF are elevated in hematologic malignancies and are adversely associated with prognosis. Angiogenesis is a very complex, tightly regulated, multistep process, the targeting of which may well prove useful in the creation of novel therapeutic agents. Current approaches being investigated include the inhibition of angiogenesis stimulants (e.g., VEGF), or their receptors, blockade of endothelial cell activation, inhibition of matrix metalloproteinases, and inhibition of tumor vasculature. Preclinical, phase I, and phase II studies of both monoclonal antibodies to VEGF and blockers of the VEGF receptor tyrosine kinase pathway indicate that these agents are safe and offer potential clinical utility in patients with hematologic malignancies.

Novel agents for the therapy of acute leukemia

The leukemias are complex diseases with a wide range of clinical, morphologic, biologic, molecular, and clinical features and a consequent array of possible responses to any given intervention. Although progress has been made in the management of the leukemias, most patients who fail to respond to front-line therapies or who relapse after an initial response die from progressive disease. The balance between efficacy and toxicity of traditional cytotoxic therapies is increasingly unacceptable. As a consequence, the search for therapeutic advances is more focused on affecting the critical steps involved in the development, propagation, and mutation of malignant clones. This article briefly reviews current data on some agents being developed for the treatment of patients with leukemia, with an emphasis on modulators of angiogenesis, inhibitors of the ubiquitin-proteasome pathway, novel nucleoside analogues, and gene hypomethylation agents.

Chronic lymphocytic leukemia

This update of early stage B-cell chronic lymphocytic leukemia (B-CLL) embraces current information on the diagnosis, biology, and intervention required to more fully develop algorithms for management of this disease. Emphasis on early stage is based on the rapid advancement in our understanding of the disease parameters and our increasing ability to predict for a given early stage patient whether there is a need for more aggressive management. In Section I, Dr. Terry Hamblin addresses the nature of the disease, accurate diagnostic procedures, evidence for an early "preclinical" phase, the use of newer prognostic features to distinguish who will be likely to progress or not, and whether it is best to watch or treat early stage disease. In Section II, Dr. Neil Kay and colleagues address the biologic aspects of the disease and how they may relate to disease progression. Review of the newer insights into gene expression, recurring genetic defects, role of cytokines/autocrine pathways, and the interaction of the CLL B cell with the microenvironment are emphasized. The relationship of these events to both trigger disease progression and as opportunities for future therapeutic intervention even in early stage disease is also considered. In Section III, Dr. John Byrd and colleagues review the historical and now current approaches to management of the previously untreated progressive B-CLL patient. They discuss what decision tree could be used in the initial decision to treat a given patient. The use of single agents versus newer combination approaches such as chemoimmunotherapy are discussed here. In addition, the place of marrow transplant and some of the newer antibodies available for treatment of B-CLL are considered. Finally, a challenge to utilize our growing knowledge of the biology of B-CLL in the early stage B-CLL is proffered.

Non-malignant leukocytes delay spontaneous B-CLL cell apoptosis

Malignant B cells from chronic lymphocytic leukemia (B-CLL) patients have a long survival in vivo, although, in culture, they spontaneously die by apoptosis. Here, we analyzed the capacity of accessory leukocytes to modulate apoptosis of B-CLL cells in vitro. To this end, we performed long-term cultures using total mononuclear cells (TMC) from B-CLL patients and TMC depleted from monocytes, NK cells and T lymphocytes (B-CLL cells). In all the patients studied (n = 25) the presence of accessory leukocytes markedly prolonged the survival of B-CLL cells. The anti-apoptotic effect was exerted by monocytes and, to a lesser degree, NK cells, partially through the release of soluble factors. Indeed, accessory leukocytes separated from leukemic cells by semipermeable membranes were still able to prolong B-CLL cell survival. By flow cytometric analysis we found that the protective effect of non-malignant cells was associated with delayed down-regulation of Bcl-2 expression on leukemic cells. By contrast, the expression of Fas and Fas ligand proteins was unchanged in most samples. Our findings suggest that monocytes and NK cells, by delaying leukemic cell apoptosis, may play a role in B-CLL cell accumulation in vivo.