Targeting the endothelin axis with atrasentan, in combination with IFN-alpha, in metastatic renal cell carcinoma.

BACKGROUND: The endothelin system is involved in tumour growth. Atrasentan, a selective endothelin-A-receptor antagonist, blocks endothelin signalling. This phase I trial studied combining treatment of interferon-alpha (IFN-α) with atrasentan in renal cell carcinoma (RCC). PATIENTS AND METHODS: This study evaluated the safety and tolerance of IFN-α (9MU subcutaneously (s.c.) three times a week) in combination with atrasentan (2.5, 5 and 10 mg orally once daily) in untreated metastatic RCC. Cohort 10 mg was extended to obtain insights in efficacy and pharmacodynamics. RESULTS: Observed toxicities mainly consisted of known IFN-like toxicities (anorexia, chills, fever, fatigue and nausea), and of nasal congestion (associated to atrasentan). None of these toxicities were considered dose limiting. Cohort 10 mg was extended up to 32 patients; in a subset of patients treated according to the protocol (n=27), median overall survival (OS) was 17.3 months. One patient (3.1%) showed a partial response lasting 14.3 months. In an exploratory analysis, we observed that in the subset of patients with declining vascular endothelial growth factor (VEGF) levels (in combination with rising Endothelin-1 levels), median OS was 22.2 months compared with 2.2 months in patients with increasing VEGF levels. CONCLUSION: Combination treatment of IFN-α 9MU-α s.c. three times a week and atrasentan 10 mg once daily is tolerated. Clinical activity, especially OS, and biomarkers in our view warrant further studies targeting the endothelin axis.

Impact of integration of clinical and outpatient units on cancer patient satisfaction.

OBJECTIVE: There is an ongoing drive to measure and improve quality of care. Donabedians' quality framework with structure, process and outcome domains provides a useful hold to examine quality of care. The aim of this study was to address the effect of an intervention in hospital structure (integration of three units into one) with the purpose of improving processes (increase meeting, cooperation and communication between professionals and patients) and its effect on the outcome (cancer patient satisfaction). DESIGN: Pre-test-post-test. SETTING: University Medical Center Utrecht, The Netherlands, Department of Medical Oncology. PARTICIPANTS: Cancer patients (n = 174, n = 97). INTERVENTIONS: Physical integration by bringing separately located units (outpatient clinic, day-care clinic, clinical ward) together in one wing of the hospital and adjustments in communication and coordination structures. MAIN OUTCOME MEASURE: Patient satisfaction questionnaire. RESULTS: Satisfaction with care improved for six scales (27%) after integration. Effect sizes (ESs) ranged from 0.36 to 0.80, indicating a small to moderate effect. The most important improvement was found at the day-care clinic on aspects like 'the degree in which the nurses were informed about a patients situation', 'privacy', 'interior design', 'quality of hospital equipment', 'sanitary supplies' and 'waiting periods'. With regard to continuity and coordination of care, satisfaction increased for five items (28% of items concerning continuity and coordination of care). ESs ranged from 0.42 to 0.75. CONCLUSIONS: Integration of three oncology units into one unit had a positive impact on care delivery processes and resulted in improved patient satisfaction concerning care and treatment.

Two-protein signature of novel serological markers apolipoprotein-A2 and serum amyloid alpha predicts prognosis in patients with metastatic renal cell cancer and improves the currently used prognostic survival models.

BACKGROUND: In metastatic renal cell cancer (mRCC), the Memorial Sloan-Kettering Cancer Center (MSKCC) risk model is widely used for clinical trial design and patient management. To improve prognostication, we applied proteomics to identify novel serological proteins associated with overall survival (OS). PATIENTS AND METHODS: Sera from 114 mRCC patients were screened by surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF MS). Identified proteins were related to OS. Three proteins were subsequently validated with enzyme-linked immunosorbent assays and immunoturbidimetry. Prognostic models were statistically bootstrapped to correct for overestimation. RESULTS: SELDI-TOF MS detected 10 proteins associated with OS. Of these, apolipoprotein A2 (ApoA2), serum amyloid alpha (SAA) and transthyretin were validated for their association with OS (P = 5.5 x 10(-9), P = 1.1 x 10(-7) and P = 0.0004, respectively). Combining ApoA2 and SAA yielded a prognostic two-protein signature [Akaike's Information Criteria (AIC) = 732, P = 5.2 x 10(-7)]. Including previously identified prognostic factors, multivariable Cox regression analysis revealed ApoA2, SAA, lactate dehydrogenase, performance status and number of metastasis sites as independent factors for survival. Using these five factors, categorization of patients into three risk groups generated a novel protein-based model predicting patient prognosis (AIC = 713, P = 4.3 x 10(-11)) more robustly than the MSKCC model (AIC = 729, P = 1.3 x 10(-7)). Applying this protein-based model instead of the MSKCC model would have changed the risk group in 38% of the patients. CONCLUSIONS: Proteomics and subsequent validation yielded two novel prognostic markers and survival models which improved prediction of OS in mRCC patients over commonly used risk models. Implementation of these models has the potential to improve current risk stratification, although prospective validation will still be necessary.

[Angiogenesis inhibitors for the systemic treatment of metastatic renal cell carcinoma: sunitinib, sorafenib, bevacizumab and temsirolimus]. / Angiogeneseremmers voor de systemische behandeling van gemetastaseerd niercelcarcinoom: sunitinib, sorafenib, bevacizumab en temsirolimus.

Treatment of patients with metastatic renal cell carcinoma is evolving rapidly due to the advent of novel targeted therapies. Improved knowledge of the underlying pathogenesis has led to the development of drugs that modulate the dominant signal transduction pathways for this disease, which results in inhibition of angiogenesis. Recent evidence indicates that the receptor tyrosine kinase inhibitor sunitinib prolongs progression-free survival compared with interferon-alpha, especially in patients with intermediate risk. Immunotherapy with interferon-alpha or high-dose interleukin-2 should still be considered for low-risk patients, particularly those with clear-cell tumours and metastases of the lung only. In patients who fail treatment with interferon-alpha, sorafenib has been shown to improve progression-free survival. High-risk patients may benefit from treatment with temsirolimus, which inhibits mammalian target of rapamycin (mTOR) kinase activity and has shown to improve overall survival. These angiogenesis inhibitors did not receive mention in the recently published guideline 'Renal cell carcinoma'.

A phase I/II and pharmacokinetic study of irinotecan in combination with capecitabine as first-line therapy for advanced colorectal cancer.

PURPOSE: The aim of this study was to determine in patients with previously untreated advanced colorectal cancer the maximum tolerated dose (MTD) and safety profile of irinotecan in combination with capecitabine, to identify a recommended dose and to determine the response rate and time to disease progression. In addition, we aimed to explore the pharmacokinetic parameters of irinotecan and capecitabine when used in different sequences of administration, with irinotecan infusion either prior to or after the first intake of capecitabine. PATIENTS AND METHODS: One hundred patients were included: 43 patients were recruited into an extended phase I trial of alternating escalation in dose of both drugs where irinotecan was administered intravenously (i.v) on day 1 after first intake of capecitabine taken from days 1-14 twice daily, with cycles repeated every 3 weeks. After the determination of recommended dose a further 57 patients were treated in a phase II evaluation with the reverse sequence of drugs on day 1. Pharmacokinetic analysis was performed in patients treated at the recommended dose in two cohorts of patients in which the sequence of the first administration of each drug was reversed. RESULTS: The MTD of the combination was determined as irinotecan 300 mg/m2, with capecitabine 2000 mg/m2/day. Dose limiting toxicities were neutropenia and diarrhoea. The recommended dose is irinotecan intravenous (i.v.) 250 mg/m2 day 1 and capecitabine 2000 mg/m2/day days 1-14, every 3 weeks. Treatment was well tolerated, with diarrhoea the most common serious toxicity. Response rate in the phase II cohort was 42% [95% confidence interval (CI) 29% to 56%]. Median duration of response was 7.7 months (95% CI 7.5-8.9). Median time to progression was 8.3 months (95% CI 5.8-10). No significant effect on irinotecan pharmacokinetics was observed whatever the intake of capecitabine before or after irinotecan infusion. An effect of irinotecan on capecitabine and some capecitabine metabolites was observed, but irinotecan did not effect 5-fluorouracil (5-FU) pharmacokinetics. CONCLUSIONS: Irinotecan in combination with capecitabine is a well tolerated regimen with an activity comparable to, but more convenient than, irinotecan-5-FU i.v. combinations in patients with previously untreated advanced colorectal cancer. The pharmacokinetic data suggest that the sequence of administration does not impact significantly on the metabolism of the two drugs.

Phase I and pharmacokinetic study of the combination of topotecan and ifosfamide administered intravenously every 3 weeks.

To determine the maximum-tolerated dose (MTD), dose-limiting toxicities, and pharmacokinetics of topotecan administered as a 30-min intravenous (i.v.) infusion over 5 days in combination with a 1-h i.v. infusion of ifosfamide (IF) for 3 consecutive days every 3 weeks. Patients with advanced malignancies refractory to standard therapy were entered into the study. The starting dose of topotecan was 0.4 mg x m(-2) day(-1) x 5 days. Ifosfamide was administered at a fixed dose of 1.2 g x m(-2) day(-1) x 3 days. In all, 36 patients received 144 treatment courses. Owing to toxicities, the schedule of topotecan administration was reduced from 5 to 3 days. The MTD was reached at topotecan 1.2 mg x m(-2) day(-1) x 3 days with IF 1.2 g x m(-2) day(-1) x 3 days. Haematological toxicities were dose limiting. Neutropenia was the major toxicity. Thrombocytopenia and anaemia were rare. Nonhaematological toxicities were relatively mild. Partial responses were documented in three patients with ovarian cancer dosed below the MTD. Topotecan and IF did not appear to interact pharmacokinetically. The relationships between the exposure to topotecan lactone and total topotecan, and the decrease in absolute neutrophil count and the decrease in thrombocytes, were described with sigmoidal-E(max) models. The combination of 1.0 mg m(-2) day(-1) topotecan administered as a 30-min i.v. infusion daily times three with 1.2 g x m(-2) day(-1) IF administered as a 1-h i.v. infusion daily times three every 3 weeks was feasible. However, the combination schedule of topotecan and IF did result in considerable haematological toxicity and in conjunction with previously reported pronounced nonhaematological toxicities and treatment related deaths, it may be concluded that this is not a favourable combination.

Phase I clinical trial of the bispecific antibody MDX-H210 (anti-FcgammaRI x anti-HER-2/neu) in combination with Filgrastim (G-CSF) for treatment of advanced breast cancer.

A phase I study of the bispecific antibody MDX-H210 in combination with granulocyte colony-stimulating factor (G-CSF) was performed in stage IV breast carcinoma patients, overexpressing HER-2/neu. MDX-H210, constructed by crosslinking antigen binding fragments (F(ab') fragments) of monoclonal antibody (mAb) H22 to Fc gamma receptor I (FcgammaRI), and mAb 520C9 to HER-2/neu, respectively, mediates the lysis of tumour cells in vitro, and in human FcgammaRI transgenic mouse models. The proto-oncogene HER-2/neu is overexpressed in approximately 30% of breast cancer patients, and represents a promising target for antibody-based immunotherapy. Fc gamma receptor I (CD64) is an effective trigger molecule, which is expressed on monocytes/macrophages, immature dendritic cells, and G-CSF-primed polymorphonuclear cells (PMN). Patients received G-CSF (Filgrastim) for 8 consecutive days, and cohorts of three patients were treated on day 4 with escalating, single doses of MDX-H210. A total of 30 patients were included, and treatment was generally well tolerated, without reaching dose-limiting toxicity. Side effects consisted mainly of fever and short periods of chills, which were timely related to elevated plasma levels of interleukin 6 and tumour necrosis factor alpha. In the last two cohorts, MDX-H210 plasma levels exceeded 1 microg ml(-1), and on circulating myeloid cells >50% saturation of FcgammaRI was found until day 4. These effector cells were highly effective in antibody-dependent cell-mediated cytotoxicity. Immunohistochemical analyses of tumour biopsies in individual patients documented infiltration of monocytes and PMN after MDX-H210 infusion. Although the clinical course of the disease was not altered by the single dose of MDX-H210, a favourable toxicity profile--even at high doses--and remarkable biological effects were seen when combined with G-CSF. Therefore, the combination of G-CSF and MDX-H210 should be evaluated in further immunotherapeutical strategies.

Immunotherapy with concurrent subcutaneous GM-CSF, low-dose IL-2 and IFN-alpha in patients with progressive metastatic renal cell carcinoma.

The purpose of the study was to determine toxicity, efficacy and immunologic effects of concurrent subcutaneous injections of low-dose interleukin-2 (LD-IL-2), granulocyte-monocyte colony-stimulating factor (GM-CSF) and interferon-alpha 2b (IFNalpha) in progressive metastatic renal cell carcinoma. In a multicentre phase II study, 59 evaluable patients received two to six cycles of subcutaneous IL-2 (4 mIU m(-2)), GM-CSF (2.5 microg kg(-1)) and IFNalpha (5 mIU flat(-1)) for 12 days per 3 weeks with evaluation after every two cycles. Cycles were repeated in responding or stable patients. Data were analysed after a median of 30 months follow-up (range 16-48 months). In 42 patients, the immunologic response was studied and related to response and survival. The main toxicity were flu-like symptoms, malaise and transient liver enzyme elevations, necessitating IL-2 reduction to 2 mIU m(-2) in 29 patients, which should be considered the maximal tolerable dose. The response was 24% (eight out of 34, three complete response (CR), five partial response (PR)) in patients with metachronic metastases and 12% (three out of 25, 2CR, 1PR) in patients with synchronic metastases. Overall response was 19% (11 out of 59). Median survival was 9.5 months. All tested patients showed expansion and/or activation of lymphocytes, T cells and subsets, NK cells, eosinophils and monocytes. Pretreatment HLA-DR levels on monocytes and number of CD4(+)HLA-DR(+) cells correlated with response. Pretreatment number of CD4(+)HLA-DR(+) cells and postimmunotherapy levels of lymphocytes, CD3(+), CD4(+) and CD8(+) T cells, but not of NK or B cells, correlated with prolonged survival. Immunotherapy with concurrent subcutaneous GM-CSF, LD-IL-2 and IFNalpha has limited toxicity, can be given as outpatient treatment and can induce durable CR. Response and survival with this form of immunotherapy seem to be more dependent on expansion/activation of T cells than of NK cells.

[Interferon for adjuvant therapy in melanoma; although approved, not indicated]. / Interferon als adjuvante therapie bij het melanoom: wel geregistreerd, niet geïndiceerd.

The Dutch melanoma group reconsidered their 1997 consensus statement on treatment of melanoma because new studies on adjuvant treatment with interferon(IFN)-alpha have been published. These have resulted in its registration for stage IIa; for stage IIb/III IFN-alpha was already registered. Overall survival should be the main endpoint of adjuvant clinical studies, especially when treatment is associated with toxicity. Since a benefit has not been unequivocally demonstrated in melanoma with Breslow thickness > 1.5 mm and/or regional lymph node metastases, there is no need to change the Dutch consensus statement. Drug registration authorities and medical professionals should cooperate more closely.

Immunochemotherapy with interleukin-2, interferon-alpha and 5-fluorouracil for progressive metastatic renal cell carcinoma: a multicenter phase II study. Dutch Immunotherapy Working Party.

In patients with metastatic renal cell carcinoma response rates of 7-26% have been achieved with immunotherapy. A high response rate of 48% in 35 patients has been reported for treatment with the combination of interferon-alpha (IFN-alpha), interleukin-2 (IL-2) and 5-fluorouracil (5-FU) (Atzpodien et al (1993a) Eur J Cancer29A: S6-8). We conducted a multicentre phase II study to confirm these results. Metastatic renal cell carcinoma patients were treated as outpatients with an 8-week treatment cycle. Recombinant human IL-2 20 MU m(-2) was administered subcutaneously (s.c.) three times a week (t.i.w) in weeks 1 and 4 and 5 MU m(-2) t.i.w. in weeks 2 and 3. Recombinant human IFN-alpha 2a 6 MU m(-2) was administered s.c. once in weeks 1 and 4 and t.i.w. in weeks 2 and 3, and 9 MU m(-2) t.i.w. in weeks 5-8. 5-FU (750 mg m(-2)) was given as a bolus injection intravenous once a week in weeks 5-8. The treatment cycle was repeated once in case of response or minor response. Fifty-two patients entered the study. All had undergone a nephrectomy and had progressive metastatic disease. The median WHO-performance status was 1, the median number of metastatic sites was 2 (range 1-5) and the median time between the diagnosis of the primary tumour and the start of treatment was 12.9 months (range 1-153). Among the 51 patients, including four patients with early progressive disease, who were evaluable for response, the response rate was 11.8% (95% confidence interval (CI) 2.9-20.7%), with no complete responses. Median duration of response was 8.3 (range 3.8-22.4+) months. Median survival was 16.5 (range 1.8-30.5+) months. Grade 3/4 toxicity (WHO) occurred in 29/52 (55.8%) of the patients in cycle 1 and in 6/16 (37.5%) of the patients in cycle 2. It consisted mainly of anorexia, fatigue, nausea, fever and leucocytopenia. We cannot confirm the high response rate in patients with metastatic renal cell carcinoma treated with the combination of IFN-alpha, IL-2 and 5-FU, as described by Atzpodien et al.

Angiogenesis inhibitors overcome tumor induced endothelial cell anergy.

We report here that tumor angiogenesis-mediated endothelial cell (EC) anergy can be overcome by inhibitors of angiogenesis. We found previously that tumor growth, known to be dependent on angiogenesis, results in down-regulation of endothelial adhesion molecules and tumor EC anergy to inflammatory signals. We hypothesized that counteracting angiogenesis induces re-expression of adhesion molecules and normalizes responses to inflammatory cytokines. Here, we present data to show that the angiogenesis inhibitor platelet factor-4 (PF4) is able to prevent basic fibroblast growth factor (bFGF)-induced down-regulation of intercellular adhesion molecule-1 (ICAM-1). Furthermore, PF4 restores ICAM-1 expression following bFGF-induced down-regulation of ICAM-1. This PF4 effect occurs at the protein level and the RNA level and it has functional impact on leukocyte adhesion. In addition, PF4 overcomes the tumor-induced EC anergy to inflammatory signals such as tumor necrosis factor alpha (TNF alpha). Our findings may be the basis of new cancer therapies by combining anti-angiogenic therapy and immunotherapy to decrease blood vessel formation and to increase the effectiveness of inflammatory reactions against tumors.

Effect of culture conditions on endothelial cell growth and responsiveness.

The in vitro culture of endothelial cells (EC) is dependent on the presence of a coated surface and the availability of growth factors in the medium. The aim of the present research is to investigate whether in vitro EC culture conditions, such as serum source and surface coating, determine the growth characteristics of EC. The phenotype of EC was studied at the level of adhesion molecule expression and down-regulation by angiogenic factors. We found that human umbilical vein EC adhere well to and stretch well with plastic coated with fibronectin, collagen, gelatin and hyaluronan in contrast to non-coated plastic. While low in hyaluronan-coated wells, the spontaneous proliferation of EC was enhanced in fibronectin-collagen and gelatin-coated wells as compared to non-coated wells. Basic fibroblast growth factor bFGF-induced proliferation, however, was best on hyaluronan-coated plastic. A markedly up-regulated proliferation was measured on fibronectin and collagen while EC on gelatin-coated plastic only showed moderate bFGF-induced proliferation. On non-coated plastic EC were not inducible with bFGF. The induction of apoptosis by serum deprivation on these different matrices was most efficient when no coat was available or when wells were coated with hyaluronan, and bFGF inhibited apoptosis induction under all conditions. The use of different culture media demonstrated that human and bovine serum both can be used for human EC assays. The synthetic medium Utroser G prevented both spontaneous and growth factor-induced proliferation. We found that apart from some magnitude differences, the down-regulation of intercellular adhesion molecule-1 (ICAM-1) by angiogenic factors such as bFGF is not dependent on specific culture conditions.

The angiogenic factor bFGF impairs leukocyte adhesion and rolling under flow conditions.

Recirculation of leukocytes is mediated by the intricately regulated expression of adhesion molecules on both the vessel wall and leukocyte membranes. In the present paper it is demonstrated that tumor angiogenesis factors impair leukocyte rolling and adhesion under flow conditions. Three lines of evidence presented in this paper support this finding; (i) treatment of cultured endothelial cells (EC) with the angiogenic factor basic fibroblast growth factor (bFGF) results in decreased ICAM-1 expression and decreased numbers of adhering leukocytes under flow conditions. (ii) flow induced upregulation of endothelial ICAM-1 in the presence of bFGF does not yield ICAM-1 levels higher than on resting EC. (iii) bFGF decreases the TNFalpha mediated induction of E-selectin and ICAM-1 expression, resulting in decreased rolling and firm adhesion of leukocytes on the endothelial surface. For ICAM-1 it is demonstrated that bFGF inhibits TNFalpha induced levels of mRNA, and that this effects is transcriptionally regulated. These findings support our earlier described hypothesis that angiogenic factors are involved in the tumor derived escape mechanism from immune surveillance, since we demonstrate here that these mechanisms are operative under physiologic flow conditions.

CD44 is involved in tumor angiogenesis; an activation antigen on human endothelial cells.

CD44 is described to be an activation molecule in a number of different cell types. We investigated the role of CD44 on human endothelial cells (EC) and in tumor angiogenesis. Using flow cytometry we showed that EC from the vasculature of human solid tumors display an enhanced expression of CD44 as compared to EC from normal tissue. This finding was confirmed by immunohistochemical studies on frozen tissue sections. Because tumors are dependent on angiogenesis, the role of angiogenic stimuli in the enhanced CD44 expression was investigated. We found that basic fibroblast growth factor (bFGF) and vascular endothelial growth factor were able to efficiently upregulate CD44 expression on cultured human EC. The upregulation reached maximal levels after treatment for 3 days with 10 ng/mL bFGF. The physiological impact of this upregulation was shown by the enhanced binding of EC to hyaluronate after pretreatment with bFGF. In a next set of studies that were designed to unravel the regulation of CD44 expression on EC we concluded that CD44 is an activation antigen on human EC since (1) human umbilical vein derived endothelial cells, which in vivo do not express CD44, begin to express CD44 when plated and cultured, (2) CD44 expression is enhanced after subculture of confluent cultures, (3) CD44 is predominantly expressed on the BrdU incorporating subset of cultured EC. The specific expression of CD44 on activated and tumor EC prompted us to study the usefulness of CD44 as an endothelial target for therapy with immunotoxins. In vitro experiments showed that EC are efficiently killed after targeting immunotoxin to CD44.

Endothelial CD34 is suppressed in human malignancies: role of angiogenic factors.

We report the suppressed vascular CD34 expression in renal cell carcinoma. This was found by quantitatively analyzing CD34 expression on normal and tumor derived EC by flow cytometry. In vitro studies revealed that culture of umbilical cord or dermis derived microvascular EC with angiogenic factors such as basic fibroblast growth factor (bFGF) and vascular endothelial cell growth factor induced downregulation of CD34. This angiogenesis-induced downregulated expression of CD34 adhesion molecule may contribute to the tumor mediated escape mechanism from immune surveillance. It is concluded that there are quantitative differences in expression of endothelial CD34 in different compartments of the vasculature, that angiogenic factors affect this expression and that subpopulations of EC exist with differences in EAM expression.

Tumor angiogenesis is accompanied by a decreased inflammatory response of tumor-associated endothelium.

We previously showed that endothelial cells (EC) from the vasculature of human solid tumors have a decreased expression of intercellular adhesion molecule-1 (ICAM-1) and ICAM-2 as compared with normal tissue EC. This effect is explained by EC exposure to angiogenic factors. It is known that upregulation of endothelial adhesion molecules (EAM) is a sign of EC activation in inflammatory responses. We therefore tested the effect of angiogenic factors on upregulation of EAM on tumor EC and human umbilical vein EC (HUVEC) by proinflammatory cytokines. Incubation of tumor-derived EC in tumor necrosis factor alpha (TNF alpha) did result in expression levels of only 20% of the level of similarly treated normal tissue-derived EC. Pretreatment of HUVEC with 10 ng/ml basic fibroblast growth factor (bFGF) for 3 days, before TNF alpha- or interleukin-1 alpha (IL-1 alpha) stimulation, resulted in ICAM-1 levels of only 30% to 60% of cells without pretreatment. Also, the induction of vascular EC adhesion molecule-1 (VCAM-1) and E-selectin by TNF alpha was significantly inhibited by prior exposure to bFGF. Vascular endothelial growth factor had similar but less prominent effects. The effect of transforming growth factor-beta and IL-8 was studied as well. The functional relevance of the finding of a decreased EC inflammatory response was confirmed by adhesion assays. Our results show that tumor angiogenesis induces EC anergy. This may serve as a tumor-protecting mechanism by impairing the development of an efficient leukocyte infiltrate in tumors.

Endothelial intercellular adhesion molecule-1 expression is suppressed in human malignancies: the role of angiogenic factors.

Intercellular adhesion molecule 1 (ICAM-1) is involved in the recirculation of blood leukocytes and, presumably, in the infiltration of cytolytic effector leukocytes into tumors. The present report describes a down-regulated expression of vascular ICAM-1 on tumor-infiltrating endothelial cells (EC) in renal cell carcinoma. This finding was obtained by flow cytometric analysis of tumor EC compared to EC obtained from healthy tissue. Since growth of solid tumors is dependent on the formation of new blood vessels (angiogenesis), we hypothesized that angiogenic factors are responsible for the down-regulation of ICAM-1. This hypothesis was investigated in vitro using human umbilical vein- and dermis-derived EC. Using flow cytometry, we found a biphasic regulation of ICAM-1 during stimulation of cultured EC with the angiogenic agent basic fibroblast growth factor (bFGF). Although 16-24 h after activation a marked up-regulation of ICAM-1 was observed, expression was significantly decreased after 48h. The longevity of this down-regulation was at least 7 days. Northern blot analysis revealed down-regulation of the steady-state mRNA level of the gene. ICAM-2 showed similar results of intial up- and later down-regulation. Functional relevance for the changes in ICAM-1 expression was demonstrated by a corresponding biphasic regulation of EC-leukocyte adhesion after EC activation by bFGF. The described effects are specific for bFGF since other angiogenic factors (such as vascular endothelial growth factor, transforming growth factor beta, and interleukin 8) did not affect adhesion molecule expression. Subsequent experiments showed that angiogenic factors decrease the sensitivity of EC to activation with tumor necrosis factor-alpha in regard to adhesion molecule expression. The present results reveal a tumor-derived escape mechanism from cytolytic effector leukocytes by down-regulation of vascular adhesion molecules in vivo and in vitro and decreased responsiveness to proinflammatory cytokines.