Correlation between high vascular endothelial growth factor-A serum levels and treatment outcome in patients with standard-risk acute lymphoblastic leukemia: a report from Children's Oncology Group Study CCG-1962

Changes in the Concentrations of Proangiogenic Cytokines in Human Brain Glioma and Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) and glioma are some of the most common malignancies, with ALL most often affecting children and glioma affecting adult men. Proangiogenic cytokines and growth factors play an important role in the development of both of these tumors. Glioma is characterized by an extremely extensive network of blood vessels, which continues to expand mainly in the process of neoangiogenesis, the direct inducers of which are cytokines from the family of vascular endothelial growth factors, i.e., vascular endothelial growth factor (VEGF-A) and its receptor vascular endothelial growth factor receptor 2 (VEGF-R2), as well as a cytokine from the fibroblast growth factor family, fibroblast growth factor 2 (FGF-2 or bFGF). Growth factors are known primarily for their involvement in the progression and development of solid tumors, but there is evidence that local bone marrow angiogenesis and increased blood vessel density are also present in hematological malignancies, including leukemias. The aim of this study was to examine changes in the concentrations of VEGF-A, VEGF-R2, and FGF-2 (with a molecular weight of 17 kDa) in a group of patients divided into specific grades of malignancy (glioma) and a control group; changes of VEGF-A and FGF-2 concentrations in childhood acute lymphoblastic leukemia and a control group; and to determine correlations between the individual proteins as well as the influence of the patient's age, diet, and other conditions that may place the patient in the risk group. During the statistical analysis, significant differences in concentrations were found between the patient and control groups in samples from people with diagnosed glioma and from children with acute lymphoblastic leukemia, but in general, there are no significant differences in the concentrations of VEGF-A, VEGF-R2, and FGF-2 between different grades of glioma malignancy. Among individuals treated for glioma, there was no significant impact from the patient's gender and age, consumption of food from plastic packaging, frequency of eating vegetables and fruit, smoking of tobacco products, the intensity of physical exercise, or the general condition of the body (Karnofsky score) on the concentrations of the determined cytokines and receptor. The listed factors do not bring about an actual increase in the risk of developing brain glioma.

Serum Levels of Vascular Endothelial Growth Factor and Its Receptor in Newly Diagnosed Paediatric Acute Lymphoblastic Leukemia

Autocrine and paracrine loop involving vascular endothelial growth factor (VEGF) and its receptor have been described in haematological malignancies. However, scarce literature is present on angiogenesis in paediatric acute lymphoblastic leukemia (ALL) with studies showing controversial results. The aim was to study serum levels of VEGF and its receptors in paediatric ALL at the time of diagnosis and at the end of induction phase and to compare these levels with clinico-haematological parameters in these patients. Serum VEGF, VEGFR-1 and VEGFR-2 levels were measured by enzyme-linked immunoabsorbant assay at diagnosis (day 0) and at the end of induction phase (day 35) in 30 newly diagnosed paediatric ALL patients and in 10 healthy controls. Median s-VEGF was significantly lower at day 0 as compared to day 35 (196.15 vs. 606.75 pg/ml: p < 0.001). s-VEGFR-1 levels were detectable only in 7 patients at day 0 and were below detection level at day 35 in all patients. Median s-VEGFR-2 at day 0 was significantly lower as compared to day 35 (17,577.5 vs. 20,507.5 pg/ml; p = 0.005). Median VEGF-R1 showed an inverse relationship with VEGF-R2 but was statistically insignificant. All patients were in remission at the end of induction. Thus, leukemic infiltration of bone marrow affects angiogenesis and reduces pro-angiogenic markers VEGF and VEGFR-2 in serum possibly due to increased local consumption by blasts. A successful induction leads to clearing of blasts causing restoration of normal hematopoiesis with normalization of VEGF and VEGFR-2 levels.

Drug Resistance Biomarkers and Their Clinical Applications in Childhood Acute Lymphoblastic Leukemia

Biomarkers are biological molecules found in body fluids or tissues, which can be considered as indications of a normal or abnormal process, or of a condition or disease. There are various types of biomarkers based on their application and molecular alterations. Treatment-sensitivity or drug resistance biomarkers include prognostic and predictive molecules with utmost importance in selecting appropriate treatment protocols and improving survival rates. Acute lymphoblastic leukemia (ALL) is the most prevalent hematological malignancy diagnosed in children with nearly 80% cure rate. Despite the favorable survival rates of childhood ALL (chALL), resistance to chemotherapeutic agents and, as a consequence, a dismal prognosis develops in a significant number of patients. Therefore, there are urgent needs to have robust, sensitive, and disease-specific molecular prognostic and predictive biomarkers, which could allow better risk classification and then better clinical results. In this article, we review the currently known drug resistance biomarkers, including somatic or germ line nucleic acids, epigenetic alterations, protein expressions and metabolic variations. Moreover, biomarkers with potential clinical applications are discussed.

Endothelial Function in Children with Acute Lymphoblastic Leukemia (ALL) May Reflect the Clinical Outcome

Endothelial dysfunction is a common feature of early complications of hemato-oncologic therapy. The aim of our study was to assess the profile of endothelial function at diagnosis time, then during initial treatment phase of acute lymphoblastic leukemia (ALL), and to verify the presence of its correlation with early clinical outcome (ECO). 28 ALL children and 18 healthy age-matched control ones were recruited. Study group was examined at baseline and at 33rd and 78th day of treatment. At each protocol step the endothelial function was assessed by measurement of sP-selectin (CD62-P), PAI-1(serpinE1), sE-selectin (CD62E), sICAM-1(sCD54), sVCAM-1(sCD106), and VEGF concentrations. Higher baseline sICAM-1 and sVCAM-1 levels and lower sP-selectin and VEGF were observed in children with ALL. sICAM-1, sVCAM-1, and sE-selectin levels were decreasing following the treatment with protocol I. Higher sE-selectin and lower baseline sICAM-1 levels were observed in children treated unsuccessfully. Lower PAI-1 levels were observed in children who survived. Higher baseline sE-selectin levels and lower sICAM-1 and VEGF were observed in children treated unsuccessfully. A decrease in sE-selectin and lower PAI-1 at the 78th day of therapy were associated with better ECO. High baseline VEGF and sE-selectin levels, significant increase in PAI-1, and low initial sICAM-1 levels are prognostics for poorer prognosis in the ALL children.

Raised VEGF: High sensitivity and specificity in the diagnosis of POEMS syndrome

Objective

To investigate the sensitivity and the specificity of serum vascular endothelial growth factor (sVEGF) for the diagnosis of polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes (POEMS) syndrome in patients with a neuropathy (NP) and to identify confounding causes of raised vascular endothelial growth factor (VEGF) in this context to improve accuracy.

Methods

We studied the specificity and sensitivity of sVEGF for the diagnosis of POEMS syndrome in a cohort of 195 consecutive patients with an NP in serum samples from June 2009 to November 2013, including 27 untreated patients with POEMS syndrome. We then studied VEGF in other neuropathies and analyzed causes of elevated VEGF in a multiple logistic regression analysis in a larger cohort of 236 patients including 168 with a non-POEMS NP and 68 without NP.

Results

The sensitivity of elevated sVEGF for the diagnosis of POEMS was 100%. Its specificity was 91% in patients with an NP and 92% in patients with an NP and a paraproteinemia. sVEGF was much higher in POEMS before treatment. sVEGF was not significantly elevated in any non-POEMS NP or hematologic disease group. Multiple logistic regression showed that anemia with low iron was a significant predictor for elevated sVEGF and that chronic obstructive pulmonary disease (COPD) and obstructive sleep apnoea-hypopnoea syndrome were significant predictors for very elevated sVEGF.

Interpretation

We confirmed the high sensitivity and specificity of an elevated VEGF for the diagnosis of POEMS. However, VEGF testing should be repeated, particularly after acute illnesses. Raised sVEGF should be interpreted with caution unless anemias with low iron, sleep apnea, COPD, cancers, vasculitis, and chronic inflammatory diseases are excluded.

Classification of evidence

This study provides class IV evidence that elevated sVEGF levels accurately identifies patients with POEMS syndrome.

Apatinib exhibits anti-leukemia activity in preclinical models of acute lymphoblastic leukemia

Background

Acute lymphoblastic leukemia (ALL) is a clonal malignant disorder characterized by an uncontrolled proliferation of immature B or T lymphocytes. Extensive studies have suggested an involvement of angiogenesis signaling in ALL progression and resistance to treatment. Thus, targeting angiogenesis with anti-angiogenic drugs may be a promising approach for ALL treatment. In this study, we investigated the effectiveness of Apatinib, a novel receptor tyrosine kinase inhibitor selectively targeting VEGFR-2 in ALL cells.

Method

ALL cell lines were treated with different concentration of Apatinib and then CCK8 assay, flow cytometry were used to determine the IC₅₀ value and cell apoptosis, respectively. The effect of Apatinib against primary ALL cells from 11 adult patients and normal counterparts were also analyzed by apoptosis with flow cytometry. Next, we used western bolting and mass cytometry (CyTOF) assay to explore the underlying mechanism of the cytotoxicity of Apatinib. Finally, the anti-leukemia activity was further evaluated in an in vivo xenograft model of ALL.

Results

Our results showed that Apatinib significantly inhibited cell growth and promoted apoptosis in both B and T lineage ALL cell lines in a dose- and time-dependent manner. The IC₅₀ values of Apatinib against Nalm6, Reh, Jurkat and Molt4 for 48 h were 55.76 ± 13.19, 51.53 ± 10.74, 32.43 ± 5.58, 39.91 ± 9.88 μmol/L, and for 72 h were 30.34 ± 2.65, 31.96 ± 3.92, 17.62 ± 5.90, and 17.65 ± 2.17 μmol/L respectively. Similarly, Apatinib shows cytotoxic activity against primary adult ALL cells while sparing their normal counterparts in vitro. Moreover, Apatinib suppressed ALL growth and progression in an in vivo xenograft model. Mechanistically, Apatinib-induced cytotoxicity was closely associated with inhibition of VEGFR2 and its downstream signaling cascades, including the PI3 K, MAPK and STAT3 pathways.

Conclusion

Our study indicates that Apatinib exerts its anti-leukemia effect by inducing apoptosis through suppressing the VEGFR2 signaling pathway, supporting a potential role for Apatinib in the treatment of ALL.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1421-y) contains supplementary material, which is available to authorized users.

Assessment of Angiogenesis in Children with Acute Lymphoblastic Leukemia Based on Serum Vascular Endothelial Growth Factor Assay

Introduction

Vascular endothelial growth factor A (VEGFA) is a key proangiogenic cytokine. The role of angiogenesis in acute lymphoblastic leukemia (ALL) is still unclear. The purpose of the study was to assess angiogenesis in children with ALL based on serum VEGFA level determined at diagnosis and at remission with further participant subdivision into different risk groups.

Materials and Methods

Forty children, aged 3-12 years (mean age: 8 years) with newly diagnosed ALL, were enrolled in the study. The control group (Group C) was twenty healthy children. According to the risk assessment, they were classified into a standard-risk group, an intermediate-risk group (IRG), or a high-risk group (HRG).

Results

The median serum VEGFA levels at diagnosis were significantly higher in IRG and HRG as compared to Group C. The VEGFA levels at remission were significantly higher in all study groups, as compared to Group C. The differences in median values of serum VEGFA levels between the study groups both at diagnosis and at remission were not statistically significant.

Conclusions

The angiogenesis in ALL seems to be intensified at diagnosis as a result of neoplasmatic bone marrow rebuilding and at remission as its intensive recovering.

Placental growth factor: What hematologists need to know

Although first identified in placenta, the angiogenic factor known as placental growth factor (PlGF) can be widely expressed in ischemic or damaged tissues. Recent studies have indicated that PlGF is a relevant factor in the pathobiology of blood diseases including hemoglobinopathies and hematologic malignancies. Therapies for such blood diseases may one day be based upon these and ongoing investigations into the role of PlGF in sickle cell disease, acute and chronic leukemias, and complications related to hematopoietic cell transplantation. In this review, we summarize recent studies regarding the potential role of PlGF in blood disorders and suggest avenues for future research.

Angiogenic Factors Correlate with T Cell Immune Reconstitution and Clinical Outcomes after Double-Unit Umbilical Cord Blood Transplantation in Adults

Umbilical cord blood (UCB) is a valuable graft source for allogeneic hematopoietic stem cell transplantation (HSCT) in patients who lack adult donors. UCB transplantation (UCBT) in adults results in delayed immune reconstitution, leading to high infection-related morbidity and mortality. Angiogenic factors and markers of endothelial dysfunction have biologic and prognostic significance in conventional HSCT, but their role in UCBT has not been investigated. Furthermore, the interplay between angiogenesis and immune reconstitution has not been studied. Here we examined whether angiogenic cytokines, angiopoietin-1 (ANG-1) and vascular endothelial growth factor (VEGF), or markers of endothelial injury, thrombomodulin (TM) and angiopoietin-2 (ANG-2), associate with thymic regeneration as determined by T cell receptor excision circle (TREC) values and recovery of T cell subsets, as well as clinical outcomes in adult recipients of UCBT. We found that plasma levels of ANG-1 significantly correlated with the reconstitution of naive CD4+CD45RA+ and CD8+CD45RA+ T cell subsets, whereas plasma levels of VEGF displayed a positive correlation with CD4+CD45RO+ T cells and regulatory T cells and a weak correlation with TRECs. Assessment of TM and ANG-2 revealed a strong inverse correlation of both factors with naive T cells and TRECs. The angiogenic capacity of each patient's plasma, as determined by an in vitro angiogenesis assay, positively correlated with VEGF levels and with reconstitution of CD4+ T cell subsets. Higher VEGF levels were associated with worse progression-free survival and higher risk of relapse, whereas higher levels of TM were associated with chronic graft-versus-host disease and nonrelapse mortality. Thus, angiogenic factors may serve as valuable markers associated with T cell reconstitution and clinical outcomes after UCBT.

HMG-CoA reductase inhibitors as adjuvant treatment for hematologic malignancies: what is the current evidence?

Statins have been shown to possess properties that go beyond their lipid-lowering effects. These agents act on the mevalonate pathway and inhibit synthesis of cholesterol, geranylgeranyl pyrophosphate, and farnesyl pyrophosphate, which are necessary for posttranslational modification of the Rho, Rac, and Ras superfamily of proteins. Early phase studies have demonstrated that this modulation of cellular signaling can ultimately exert pro-apoptotic, anti-angiogenic, and immunomodulatory effects, and might even restore chemosensitivity in several hematologic cancers. Nonetheless, these promising preclinical results have not yet migrated from the bench to the bedside as their effectiveness as adjuvant agents in hematologic malignancies is currently uncertain. In the present review, we summarize the existing evidence stemming from preclinical and clinical studies pertaining to the use of statins as adjuvant therapies in hematologic malignancies, and discuss the new insights gained from the ongoing translational research.

Target Therapy in Hematological Malignances: New Monoclonal Antibodies

Apart from radio- and chemotherapy, monoclonal antibodies (MoAbs) represent a new, more selective tool in the treatment of hematological malignancies. MoAbs bind with the specific antigens of the tumors. This interaction is a basis for targeted therapies which exhibit few side effects and significant antitumor activity. This review provides an overview of the functional characteristics of MoAbs, with some examples of their clinical application. The promising results in the treatment of hematological malignancies have led to the more frequent usage of MoAbs in the therapy. Development of MoAbs is a subject of extensive research. They are a promising method of cancer treatment in the future.

Hypoxia-related gene expression profile in childhood acute lymphoblastic leukemia: prognostic implications

A cellular hypoxic condition is a key event in several human cancers, but knowledge about its role in childhood acute lymphoblastic leukemia (ALL) is very limited. In the present study, the gene expression profile of hypoxia-related genes (HIF1A, CA9, VEGF and SCL2A1) was evaluated in bone marrow samples of 113 pediatric patients. HIF1A mRNA up-regulation was significantly associated with higher 5-year event-free survival rates in patients with B-ALL as well as in the overall ALL population in both univariate and multivariate analysis (p = 0.023 and p = 0.041, respectively). In gene expression analysis, low oxygen levels promoted HIF1A activation in a time-dependent manner, in both ALL cell lines. In vitro cytotoxic assays suggested an initial trend toward hypoxia-related resistance in the first 24 h, but evaluation at later time points (48-72 h) clearly showed that there was no relevant difference in drug response when comparing hypoxic and normal oxygen level conditions. Modulation of mRNA expression of several hypoxia-related genes was also observed after hypoxic exposure in a cell specific manner, suggesting that HIF1A mRNA expression could play a different role in specific subtypes of leukemia. Despite the remaining questions regarding hypoxia-mediated mechanisms, these findings could be helpful to provide new insights into the role of hypoxia in childhood ALL.

Pediatric relapsed or refractory leukemia: new pharmacotherapeutic developments and future directions

Over the past 50 years, numerous advances in treatment have produced dramatic increases in the cure rates of pediatric leukemias. Despite this progress, the majority of children with relapsed leukemia are not expected to survive. With current chemotherapy regimens, approximately 15 % of children with acute lymphoblastic leukemia and 45 % of children with acute myeloid leukemia will have refractory disease or experience a relapse. Advances in the treatment of pediatric relapsed leukemia have not mirrored the successes of upfront therapy, and newer treatments are desperately needed in order to improve survival in these challenging patients. Recent improvements in our knowledge of cancer biology have revealed an extensive number of targets that have the potential to be exploited for anticancer therapy. These advances have led to the development of a number of new treatments that are now being explored in children with relapsed or refractory leukemia. Novel agents seek to exploit the same molecular aberrations that contribute to leukemia development and resistance to therapy. Newer classes of drugs, including monoclonal antibodies, tyrosine kinase inhibitors and epigenetic modifiers are transforming the treatment of patients who are not cured with conventional therapies. As the side effects of many new agents are distinct from those seen with conventional chemotherapy, these treatments are often explored in combination with each other or combined with conventional treatment regimens. This review discusses the biological rationale for the most promising new agents and the results of recent studies conducted in pediatric patients with relapsed leukemia.

Serum vascular endothelial growth factor-a levels during induction therapy in children with acute lymphoblastic leukemia

OBJECTIVE

To evaluate serum vascular endothelial growth factor (VEGF) levels in children with acute lymphoblastic leukemia (ALL) during the induction phase of chemotherapy.

DESIGN

Prospective sudy.

SETTING

Setting: Hospital-based study over 18 months.

PATIENTS

30 children with ALL and 17 healthy age- and sex-matched controls.

INTERVENTION

Serum concentration of VEGF-A-165 isoform (s-VEGF) was measured by enzyme-linked immunoabsorbant assay at diagnosis and at the end of induction chemotherapy.

MAIN OUTCOME MEASURES

s-VEGF was compared with markers of tumor burden. Kinetics of s-VEGF was assessed in response to induction chemotherapy.

RESULTS

Median VEGF was significantly lower in untreated patients than in controls (17.0 vs. 42.6 pg/mL, P=0.004). s-VEGF levels were fairly correlated with WBC count (r=-0.56, P=0.004) and LDH (r=-0.52, P=0.02) at diagnosis. All patients but one were in morphologic remission at the end of induction. Median s-VEGF concentration on day 29/33 was significantly higher than on day 1 (44.2 pg/mL, P=0.009).

CONCLUSIONS

Untreated children with ALL have significantly lower s-VEGF concentration than controls. At the end of the induction therapy, s-VEGF increased to levels similar to controls. The role of ligand-receptor interaction between VEGF and VEGF receptors on leukemia cells needs to be further delineated.To identify the risk factors for scholastic backwardness in children.

Induction of vascular endothelial growth factor secretion by childhood acute lymphoblastic leukemia cells via the FLT-3 signaling pathway

Human leukemia cells secrete VEGF, which can act in a paracrine manner within the bone marrow microenvironment to promote leukemia cell survival and proliferation. The FLT-3 receptor tyrosine kinase plays an essential role in regulating normal hematopoiesis, but its constitutive activation via mutation in acute leukemias is generally associated with poor outcome. The aim of this study was to investigate interactions between the FLT-3 and VEGF signaling pathways in acute leukemia using cell lines and ex vivo cultures of pediatric acute lymphoblastic leukemia cells following expansion of direct patient explants in immunodeficient mice. Different xenograft lines exhibited variable cell surface FLT-3 expression, as well as basal and FLT-3 ligand-induced VEGF secretion, whereas the MV4;11 cell line, which expresses constitutively active FLT-3, secreted high levels of VEGF. The FLT-3 inhibitor, SU11657, significantly reduced VEGF secretion in three of six xenograft lines and MV4;11 cells, in conjunction with inhibition of FLT-3 tyrosine phosphorylation. Moreover, exposure of xenograft cells to the FLT-3-blocking antibody, D43, also reduced VEGF secretion to basal levels and decreased FLT-3 tyrosine phosphorylation. In terms of downstream signaling, SU11657 and D43 both caused dephosphorylation of extracellular signal-regulated kinase 1/2, with no changes in AKT or STAT5 phosphorylation. Finally, partial knockdown of FLT-3 expression by short interfering RNA also resulted in inhibition of VEGF secretion. These results indicate that FLT-3 signaling plays a central role in the regulation of VEGF secretion and that inhibition of the FLT-3/VEGF pathway may disrupt paracrine signaling between leukemia cells and the bone marrow microenvironment.

What role for angiogenesis in childhood acute lymphoblastic leukaemia?

The role of angiogenesis in acute leukaemia has been discussed since the cloning of the gene of vascular endothelial growth factor (VEGF) from the acute myelogenous leukemia cell line (HL60) and, thereafter, when the first studies reported increased bone marrow vascularity and elevation of angiogenic cytokines in acute lymphoblastic leukaemia (ALL). VEGF and basic fibroblast growth factor (bFGF) are the major proangiogenic cytokines that have been studied, and evaluation of their prognostic impact in childhood ALL has been reported in several studies, though with controversial results. The antiangiogenic response, contributing to the angiogenic balance, has scarcely been reported. The origin of the factors, their prognostic value, and their relevance as good markers of what really happens in the bone marrow are discussed in this paper. The place of antiangiogenic drugs in ALL has to be defined in the global treatment strategy.

Bevacizumab potentiates chemotherapeutic effect on T-leukemia/lymphoma cells by direct action on tumor endothelial cells

Vascular endothelial growth factor-A, an angiogenesis stimulator expressed on both tumor endothelial and malignant T cells, is involved in tumor progression in T-leukemia/lymphoma. Here, we assessed the impact of therapeutic vascular endothelial growth factor-A blockade on tumor-endothelial cell interaction and on tumor progression. In a murine xenograft T-leukemia/lymphoma model, combined bevacizumab (monoclonal antibody against vascular endothelial growth factor-A) with doxorubicin, compared with doxorubicin alone, significantly delayed tumor growth and induced prevalence of tumor cell apoptosis over mitosis. More importantly, the combined treatment induced endothelial cell swelling, microvessel occlusions, and tumor necrosis. In vitro, co-culture of endothelial cells with T-leukemia/lymphoma cells showed that doxorubicin induced expression of intracellular cell adhesion molecule-1, provided endothelial and malignant T cells were in direct contact. This was abrogated by bevacizumab treatment with doxorubicin. Taken together, bevacizumab enhances the chemotherapeutic effect on T-leukemia/lymphoma cells. Directly targeting tumor endothelial cells might be a promising therapeutic strategy to counteract tumor progression in T-cell malignancies.

Vandetanib mediates anti-leukemia activity by multiple mechanisms and interacts synergistically with DNA damaging agents

Vandetanib is an orally active small molecule tyrosine kinase inhibitor (TKI) with activity against several pathways implicated in malignancy including the vascular endothelial growth factor receptor pathway, the epidermal growth factor receptor pathway, the platelet derived growth factor receptor β pathway, and REarranged during Transfection pathway. To determine if vandetanib-mediated inhibition of receptor tyrosine kinases is a potential therapeutic strategy for pediatric acute leukemia, these studies aimed to characterize the activity of vandetanib against acute leukemia in vitro. Treatment of leukemia cell lines with vandetanib resulted in a dose-dependent decrease in proliferation and survival. Vandetanib's anti-leukemic activity appeared mediated by multiple mechanisms including accumulation in G1 phase at lower concentrations and apoptosis at higher concentrations. Alterations in cell surface markers also occurred with vandetanib treatment, suggesting induction of differentiation. In combination with DNA damaging agents (etoposide and doxorubicin) vandetanib demonstrated synergistic induction of cell death. However in combination with the anti-metabolite methotrexate, vandetanib had an antagonistic effect on cell death. Although several targets of vandetanib are expressed on acute leukemia cell lines, expression of vandetanib targets did not predict vandetanib sensitivity and alone are therefore not likely candidate biomarkers in patients with acute leukemia. Interactions between vandetanib and standard chemotherapy agents in vitro may help guide choice of combination regimens for further evaluation in the clinical setting for patients with relapsed/refractory acute leukemia. Taken together, these preclinical data support clinical evaluation of vandetanib, in combination with cytotoxic chemotherapy, for pediatric leukemia.

Does serum soluble vascular endothelial growth factor levels have different importance in pediatric acute leukemia and malignant lymphoma patients?

Vascular endothelial growth factor (VEGF) seems to play a central role in angiogenesis-lymphangiogenesis in hematological malignancies. There are limited data related to childhood hematologic malignancies. The aim of the study was to evaluate soluble VEGF (sVEGF) levels in children with acute leukemia and malignant lymphoma (ML) at diagnosis and in remission. The levels of serum sVEGF were measured by enzyme-linked immunosorbent assay (ELISA) in 20 children with acute leukemia, 33 children with different histopathological subtypes of ML, and 20 healthy controls. The levels of sVEGF at diagnosis (range 2 -1040 pg/mL; median 52 pg/mL) was significantly lower than in remission (range 136 -1960 pg/mL; median 630 pg/mL) in acute myeloid leukemia (AML) group (P = .018). The sVEGF levels at diagnosis (range: 2 -640 pg/mL; median 89 pg/mL) was significantly lower compared to remission values (range: 116 -1960 pg/mL; median 136 pg/mL) in patients with acute lymphoblastic leukemia (ALL) (P = .002). In ML group, including Burkitt's lymphoma (BL), T-cell non-Hodgkin's lymphoma (NHL), and Hodgkin's lymphoma (HL), sVEGF levels at diagnosis were higher than remission levels, but there was no statistically significant difference (P >.05). On the other hand, there were significant difference between levels in active disease and control group, ie, BL versus control, T-cell NHL versus control, and HL versus control (P = .008, P = .043, P = .007, respectively). The authors noticed that sVEGF levels showed distinct behavioral pattern in different childhood malignancies at diagnosis and in remission. In acute leukemia and ML patients, VEGF acts through different pathophysiological mechanisms, in both bone marrow (BM) angiogenesis and lymphoid tissue lymphangiogenesis.

Vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (NOS3) polymorphisms are associated with high relapse risk in childhood acute lymphoblastic leukemia (ALL)

BACKGROUND

Angiogenesis has been shown as an important process in hematological malignancies. It consists in endothelial proliferation, migration, and tube formation following pro-angiogenic factors releasing, specially the vascular endothelial growth factor (VEGF), which angiogenic effect seems to be dependent on nitric oxide (NO). We examined the association among functional polymorphisms in these two angiogenesis related genes: VEGF (-2578C>A, -1154G>A, and -634G>C) and NOS3 (-786T>C, intron 4 b>a, and Glu298Asp) with prognosis of childhood acute lymphoblastic leukemia (ALL).

METHODS

The genotypes were determined and haplotypes estimated in 105 ALL patients that were divided in 2 groups: high risk (HR) and low risk of relapse (LR) patients. In addition, event-free survival curves according to genotypes were assessed.

RESULTS

The group HR compared to the LR showed a higher frequency of the alleles -2578C and -634C and the haplotype CGC for VEGF (0.72 vs. 0.51, p<0.008; 0.47 vs. 0.26, p<0.008; and 42.1 vs. 14.5, p<0.006; respectively) and a lower frequency of the haplotype CbGlu (0.4 vs. 8.8,p<0.006), for NOS3.

CONCLUSION

Polymorphisms of VEGF and NOS3 genes are associated with high risk of relapse, therefore may have a prognostic impact in childhood ALL.

Vascular density in childhood acute lymphoblastic leukaemia correlates to biological factors and outcome

The issue of angiogenesis and its clinical relevance in childhood acute lymphoblastic leukaemia (ALL) is controversial. In the present study, microvessel density (MVD), analysed in 185 diagnostic bone marrow biopsies, was higher in T-cell ALL compared to B-cell precursor (BCP)-ALL (P = 0.013). In the BCP group, cases with t(12;21) were characterized by a low MVD while patients with high-hyperdiploid leukaemia (HeH, 51-61 chromosomes) showed a high MVD compared to other BCP patients (P = 0.001 and 0.002 respectively). There was a correlation between MVD and white blood cell (WBC) count in high-risk BCP patients (P = 0.021). In addition, BCP patients with a high marrow reticulin fibre density and high MVD had an unfavourable outcome compared to the other BCP patients (P = 0.002). The fraction of vessels in which lumina were filled with blasts (blast congested vessel fraction) correlated strongly with WBC count (P < 0.001). These findings indicate that the angiogenic process interacts with other stroma-factors, such as reticulin fibre density, in its effect on outcome, and is coupled to both the ALL genotype and phenotype. One possible implication is that different subtypes of childhood ALL may respond differently to anti-angiogenic drugs as a supplement in first-line treatment.

Initial testing (stage 1) of sunitinib by the pediatric preclinical testing program

BACKGROUND

Sunitinib is an orally bioavailable, multi-targeted tyrosine kinase inhibitor with selectivity for PDGF receptors, VEGF receptors, FLT3, and KIT.

PROCEDURES

Sunitinib was tested at concentrations ranging from 0.1 nM to 1.0 microM against 23 cell lines from the PPTP in vitro panel. We also compared sunitinib (53.5 mg/kg) or vehicle administered for 28 days by oral gavage in 46 murine xenograft models representing 9 distinct pediatric cancer histologies.

RESULTS

The leukemia cell line, Kasumi-1 (gain-of-function KIT(Asn822Lys) mutation) was the only line with an in vitro response to sunitinib (IC(50) 75.7 nM). Sunitinib significantly prolonged EFS in 19 of 35 (54%) of the solid tumor, and in 3 of 8 (38%) of the ALL xenografts analyzed. Using the PPTP time to event measure of efficacy, sunitinib had intermediate (13) and high (1) levels of activity against 14 of 34 evaluable solid tumor xenografts, including 4 of 6 rhabdomyosarcoma, 4 of 5 Ewing tumor, and 2 of 3 rhabdoid tumor xenografts. Following cessation of treatment for the 14 solid tumor xenografts without tumor events by day 28, tumor growth rate increased in most. The only regression noted to sunitinib in the solid tumor panels was a complete response in a rhabdoid tumor xenograft.

CONCLUSIONS

Sunitinib demonstrated significant tumor growth inhibition against most of the PPTP's solid tumor panels, but little activity against the neuroblastoma and ALL panel. Antitumor activity was manifested primarily as tumor growth delay, consistent with an anti-angiogenic effect for sunitinib against many of the pediatric preclinical models evaluated. Pediatr Blood Cancer 2008;51:42-48. (c) 2008 Wiley-Liss, Inc.

Initial testing of the VEGFR inhibitor AZD2171 by the pediatric preclinical testing program

BACKGROUND

Inhibition of vascular endothelial growth factor mediated signaling shows promise as an antiangiogenic strategy for solid tumors. AZD2171 is a potent and relatively selective inhibitor of the vascular endothelial growth factor (VEGF) receptor family that is orally bioavailable. This study was designed to screen for antitumor activity of AZD2171 against the in vitro and in vivo childhood cancer preclinical models of the Pediatric Preclinical Testing Program (PPTP).

PROCEDURES

AZD2171 was tested at concentrations from 0.1 nM to 1.0 microM against the in vitro panel and was tested against the in vivo tumor panels using a 6-week exposure to daily gavage administration of AZD2171 (3 or 6 mg/kg) or vehicle.

RESULTS

One of 22 cell lines evaluated was sensitive to AZD2171 in vitro (maximum concentration 1 microM). Evidence of in vivo antitumor activity (primarily tumor growth delay) was observed in 78% of solid tumor xenografts (3/3 rhabdoid, 2/3 Wilms', 3/3 Ewing's, 5/5 rhabdomyosarcoma, 1/3 medulloblastoma, 2/4 glioblastoma, 5/6 neuroblastoma, 4/5 osteosarcoma). Objective responses (both complete responses) were observed in two of 32 (6%) solid tumor xenografts (a rhabdoid xenograft and an osteosarcoma xenograft). No activity was observed against 7 acute lymphoblastic leukemia models.

CONCLUSIONS

AZD2171 demonstrated broad tumor growth inhibition against the PPTP's solid tumor xenografts and much less commonly induced tumor regression. This pattern of in vivo activity, combined with the disassociation of in vitro and in vivo efficacy, are consistent with AZD2171 inhibiting growth of the PPTP's solid tumor xenografts primarily through an anti-angiogenesis mechanism of action.

The cellular adaptations to hypoxia as novel therapeutic targets in childhood cancer

Exposure of tumour cells to reduced levels of oxygen (hypoxia) is a common finding in adult tumours. Hypoxia induces a myriad of adaptive changes within tumour cells which result in increased anaerobic glycolysis, new blood vessel formation, genetic instability and a decreased responsiveness to both radio and chemotherapy. Hypoxia correlates with disease stage and outcome in adult epithelial tumours and increasingly it is becoming apparent that hypoxia is also important in paediatric tumours. Despite its adverse effects upon tumour response to treatment hypoxia offers several avenues for new drug development. Bioreductive agents already exist, which are preferentially activated in areas of hypoxia, and thus have less toxicity for normal tissue. Additionally the adaptive cellular response to hypoxia offers several novel targets, including vascular endothelial growth factor (VEGF), carbonic anhydrase, and the central regulator of the cellular response to hypoxia, hypoxia inducible factor-1 (HIF-1). Novel agents have emerged against all of these targets and are at various stages of clinical and pre-clinical development. Hypoxia offers an exciting opportunity for new drug development that can include paediatric tumours at an early stage.