Ferumoxides-protamine sulfate is more effective than ferucarbotran for cell labeling: implications for clinically applicable cell tracking using MRI.

The use of superparamagnetic iron oxide (SPIO) for labeling cells holds great promise for clinically applicable cell tracking using magnetic resonance imaging. For clinical application, an effectively and specifically labeled cell preparation is highly desired (i.e. a large amount of intracellular iron and a negligible amount of extracellular iron). In this study we performed a direct comparison of two SPIO labeling strategies that have both been reported as efficient and clinically translatable approaches. These approaches are cell labeling using ferumoxides-protamine complexes or ferucarabotran particles. Cell labeling was performed on primary human bone marrow stromal cells (hBMSCs) and chondrocytes. For both cell types ferumoxides-protamine resulted in a higher percentage of labeled cells, a higher total iron load, a larger amount of intracellular iron and a lower amount of extracellular iron aggregates, compared with ferucarbotran. Consequently, hBMSC and chondrocyte labeling with ferumoxides-protamine is more effective and results in more specific cell labeling than ferucarbotran.

Histamine, a vasoactive agent with vascular disrupting potential, improves tumour response by enhancing local drug delivery.

Tumour necrosis factor (TNF)-based isolated limb perfusion (ILP) is an approved and registered treatment for sarcomas confined to the limbs in Europe since 1998, with limb salvage indexes of 76%. TNF improves drug distribution in solid tumours and secondarily destroys the tumour-associated vasculature (TAV). Here we explore the synergistic antitumour effect of another vasoactive agent, histamine (Hi), in doxorubicin (DXR)-based ILP and evaluate its antivascular effects on TAV. We used our well-established rat ILP model for in vivo studies looking at tumour response, drug distribution and effects on tumour vessels. In vitro studies explored drug interactions at cellular level on tumour cells (BN-175) and Human umbilical vein endothelial cells (HUVEC). There was a 17% partial response and a 50% arrest in tumour growth when Hi was combined to DXR, without important side effects, against 100% progressive disease with DXR alone and 29% arrest in tumour growth for Hi alone. Histology documented an increased DXR leakage in tumour tissue combined to a destruction of the TAV, when Hi was added to the ILP. In vitro no synergy between the drugs was observed. In conclusion, Hi is a vasoactive drug, targeting primarily the TAV and synergises with different chemotherapeutic agents.

Impaired neutralising antibody formation and high transduction efficacy after isolated hepatic perfusion with adenoviral vectors.

Local adenoviral gene transfer can be performed by means of isolated hepatic perfusion (IHP). This methodology is a very effective and safe way to deliver adenoviral vectors. We studied the immune response after IHP. A decreased neutralising antibody formation was observed, offering possibilities for further research in the field of gene therapy in isolated perfusion settings.

Dynamic contrast-enhanced MRI using macromolecular contrast media for monitoring the response to isolated limb perfusion in experimental soft-tissue sarcomas.

The objective of this study was to evaluate the potential of dynamic contrast-enhanced MRI for quantitative characterization of tumor microvessels and to assess the microvascular changes in response to isolated limb perfusion with TNF-alpha and melphalan. Dynamic contrast-enhanced MRI was performed in an experimental cancer model, using a macromolecular contrast medium, albumin-(Gd-DTPA)45. Small fragments of BN 175, a soft-tissue sarcoma, were implanted in 11 brown Norway (BN) rats. Animals were assigned randomly to a control (Haemaccel) or drug-treated group (TNF-alpha/melphalan). MRI was performed at baseline and 24 h after ILP. The transendothelial permeability (K(PS)) and the fractional plasma volume (fPV) were estimated from the kinetic analysis of MR data using a two-compartment bi-directional model. K(PS) and fPV decreased significantly in the drug-treated group compared to baseline (p<0.05). In addition, K(PS) post therapy was significantly lower (p<0.05) in the drug-treated group than in the control group. There was no significant difference in fPV between the drug-treated and the control group after therapy. Tumor microvascular changes in response to isolated limb perfusion can be determined after 24 h by dynamic contrast-enhanced MRI. The data obtained in this experimental model suggest possible applications in the clinical setting, using the appropriate MR contrast agents.

Lack of efficacy of Doxil in TNF-alpha-based isolated limb perfusion in sarcoma-bearing rats.

Here we show that Doxil has minimal antitumour activity in the isolated limb perfusion (ILP) setting and its activity was not enhanced by the addition of tumour necrosis factor (TNF). Doxil accumulation in tumour tissue was low and also not augmented by TNF. In contrast, activity of free conventional doxorubicin was enhanced by TNF. We conclude that application of Doxil in a TNF-based ILP is not a useful alternative to free conventional doxorubicin or melphalan.

Degree of tumour vascularity correlates with drug accumulation and tumour response upon TNF-alpha-based isolated hepatic perfusion.

Isolated hepatic perfusion (IHP) with melphalan with or without tumour necrosis factor alpha (TNF-alpha) is currently performed in clinical trials in patients with hepatic metastases. Previous studies led to the hypothesis that the use of TNF-alpha in isolated limb perfusion causes specific destruction of tumour endothelial cells and thereby induces an increased permeability of tumour vasculature. However, whether TNF-alpha contributes to the therapeutic efficacy in IHP still remains unclear. In an in vivo rat liver metastases model we studied three different tumours: colon carcinoma CC531, ROS-1 osteosarcoma and BN-175 soft-tissue sarcoma which exhibit different degrees of vascularisation. IHP was performed with melphalan with or without the addition of TNF-alpha. IHP with melphalan alone resulted, in all tumour types, in a decreased growth rate. However in the BN-175 tumour addition of TNF-alpha resulted in a strong synergistic effect. In the majority of the BN-175 tumour-bearing rats, a complete response was achieved. In vitro cytoxicity studies showed no sensitivity (CC531 and BN-175) or only minor sensitivity (ROS-1) to TNF-alpha, ruling out a direct interaction of TNF-alpha with tumour cells. The response rate in BN-175 tumour-bearing rats when TNF-alpha was coadministrated with melphalan was strongly correlated with drug accumulation in tumour tissue, as only in these rats a five-fold increased melphalan concentration was observed. Secondly, immunohistochemical analysis of microvascular density (MVD) of the tumour showed a significantly higher MVD for BN-175 tumour compared to CC531 and ROS-1. These results indicate a direct relation between vascularity of the tumour and TNF-alpha mediated effects. Assessment of the tumour vasculature of liver metastases would be a way of establishing an indication for the utility of TNF-alpha in this setting.

Improved antitumor response to isolated limb perfusion with tumor necrosis factor after upregulation of endothelial monocyte-activating polypeptide II in soft tissue sarcoma.

BACKGROUND: Experiments with tumor necrosis factor alpha (TNF) in rodents have shown that a high dose can lead to hemorrhagic necrosis in tumors. Endothelial monocyte-activating polypeptide II (EMAP-II) is a novel tumor-derived cytokine, and its expression increases the TNF-1 receptor on tumor endothelium, enhances the induction of tissue factor on tumor endothelial cells, and has an antiangiogenic effect. It has recently been shown that in vivo sensitivity of tumor vasculature to TNF is determined by tumor production of EMAP-II. METHODS: We measured the level of EMAP-II in a TNF-resistant soft tissue sarcoma. We subsequently stabile-transfected this cell line with a retroviral construct containing the EMAP gene. In an extremity perfusion model in tumor-bearing rats, we measured response rates to TNF therapy. RESULTS: Functional EMAP-II production was increased after this transfection. Immunostaining of paraffin-embedded tumor tissue sections in rats showed an overexpression of human EMAP-II. Results of the TNF perfusions in rats suggest that this tumor is more sensitive to TNF therapy. CONCLUSIONS: EMAP-II is produced in various levels. One can increase the sensitivity of tumor for TNF therapy in vivo by upregulating the EMAP-II production. This result leaves an opportunity for enhanced TNF response of tumors in future settings.

Isolated limb perfusion with actinomycin D and TNF-alpha results in improved tumour response in soft-tissue sarcoma-bearing rats but is accompanied by severe local toxicity.

Previously we demonstrated that addition of Tumour Necrosis Factor-alpha to melphalan or doxorubicin in a so-called isolated limb perfusion results in synergistic antitumour responses of sarcomas in both animal models and patients. Yet, 20 to 30% of the treated tumours do not respond. Therefore agents that synergise with tumour necrosis factor alpha must be investigated. Actinomycin D is used in combination with melphalan in isolated limb perfusion in the treatment of patients with melanoma in-transit metastases and is well known to augment tumour cell sensitivity towards tumour necrosis factor alpha in vitro. Both agents are very toxic, which limits their systemic use. Their applicability may therefore be tested in the isolated limb perfusion setting, by which the tumours can be exposed to high concentrations in the absence of systemic exposure. To study the beneficial effect of the combination in vivo, BN-175 soft tissue sarcoma-bearing rats were perfused with various concentrations of actinomycin D and tumour necrosis factor alpha. When used alone the drugs had only little effect on the tumour. Only when actinomycin D and tumour necrosis factor alpha were combined a tumour response was achieved. However, these responses were accompanied by severe, dose limiting, local toxicity such as destruction of the muscle tissue and massive oedema. Our results show that isolated limb perfusion with actinomycin D in combination with tumour necrosis factor alpha leads to a synergistic anti-tumour response but also to idiosyncratic locoregional toxicity to the normal tissues. Actinomycin D, in combination with tumour necrosis factor alpha, should not be explored in the clinical setting because of this. The standard approach in the clinic remains isolated limb perfusion with tumour necrosis factor alpha in combination with melphalan.

Adenovirus-mediated interleukin 3 beta gene transfer by isolated limb perfusion inhibits growth of limb sarcoma in rats.

Cytokine gene transfer using (multiple) intratumoral injections can induce tumor regression in several animal models, but this administration technique limits the use for human gene therapy. In the present studies we describe tumor growth inhibition of established limb sarcomas after a single isolated limb perfusion (ILP) with recombinant adenoviral vectors harboring the rat IL-3 beta gene (IG.Ad.CMV.rIL-3 beta). In contrast, a single intratumoral injection or intravenous administration did not affect tumor growth. Dose-finding studies demonstrated a dose-dependent response with a loss of antitumor effect below 1 x 10(9) IU of IG.Ad.CMV.rIL-3 beta. Perfusions with adenoviral vectors bearing a weaker promoter (MLP promoter) driving the rIL-3 beta gene did not result in antitumor responses, suggesting that the rIL-3 beta-mediated antitumor effect depends on the amount of rIL-3 beta protein expressed by the infected cells. Furthermore, it was shown by direct comparison that ILP with IG.Ad.CMV.rIL-3 beta in the ROS-1 osteosarcoma model is at least as efficient as the established therapy with the combination of TNF-alpha and melphalan. Treatment with IG.Ad.CMV.rIL-3 beta induced a transient dose-dependent leukocytosis accompanied by an increase in peripheral blood levels of histamine. Leukocyte infiltrations were also histopathologically demonstrated in tumors after perfusion. These results demonstrate that ILP with recombinant adenoviral vectors carrying the IL-3 beta transgene inhibits tumor growth in rats and suggest that cytokine gene therapy using this administration technique might be beneficial for clinical cancer treatment.

Nitric oxide synthase inhibition results in synergistic anti-tumour activity with melphalan and tumour necrosis factor alpha-based isolated limb perfusions.

Nitric oxide (NO) is an important molecule in regulating tumour blood flow and stimulating tumour angiogenesis. Inhibition of NO synthase by L-NAME might induce an anti-tumour effect by limiting nutrients and oxygen to reach tumour tissue or affecting vascular growth. The anti-tumour effect of L-NAME after systemic administration was studied in a renal subcapsular CC531 adenocarcinoma model in rats. Moreover, regional administration of L-NAME, in combination with TNF and melphalan, was studied in an isolated limb perfusion (ILP) model using BN175 soft-tissue sarcomas. Systemic treatment with L-NAME inhibited growth of adenocarcinoma significantly but was accompanied by impaired renal function. In ILP, reduced tumour growth was observed when L-NAME was used alone. In combination with TNF or melphalan, L-NAME increased response rates significantly compared to perfusions without L-NAME (0-64% and 0-63% respectively). An additional anti-tumour effect was demonstrated when L-NAME was added to the synergistic combination of melphalan and TNF (responses increased from 70 to 100%). Inhibition of NO synthase reduces tumour growth both after systemic and regional (ILP) treatment. A synergistic anti-tumour effect of L-NAME is observed in combination with melphalan and/or TNF using ILP. These results indicate a possible role of L-NAME for the treatment of solid tumours in a systemic or regional setting.

Tumor necrosis factor-alpha augments tumor effects in isolated hepatic perfusion with melphalan in a rat sarcoma model.

Isolated hepatic perfusion (IHP) is an attractive approach to treating nonresectable liver tumors, because the effects of systemic chemotherapy are poor and its application is hampered by severe general toxicity. In clinical and experimental settings, the efficacy of isolated limb perfusion (ILP) with tumor necrosis factor-alpha (TNF alpha) in combination with melphalan to treat melanoma in transit and soft-tissue sarcoma has been well established. In an ILP model in rats, the authors previously observed synergistic anti-tumor effects of TNF and melphalan on BN 175 soft-tissue sarcoma extremity tumors. The aim of the current study was to determine whether similar synergy in anti-tumor effects could be achieved by treating experimental BN 175 soft-tissue sarcoma liver tumors by IHP using these agents. The authors found that IHP with TNF and melphalan resulted in a dramatic increase in regional concentrations of perfused agents with virtually no concomitant systemic leakage. Isolated hepatic perfusion with only carrier solution resulted in a significantly diminished growth rate of BN 175 liver tumors compared with the growth rate of tumors in nonperfused rats. Perfusion with melphalan alone resulted in minimal anti-tumor effects. Perfusion with only TNF had a slight growth-stimulatory effect on the BN 175 liver tumors, but no negative effects on tumor growth were observed. When TNF was added to melphalan, a dramatic anti-tumor effect was observed. Thus, as in the rat ILP setting, the anti-tumor effect is augmented when TNF is added to IHP with melphalan to treat BN 175 soft-tissue sarcoma tumor-bearing rats. Strikingly, the tumor response was potentiated at relatively low concentrations of TNF compared with concentrations that elicited synergy with melphalan in ILP.

Low-dose tumor necrosis factor-alpha augments antitumor activity of stealth liposomal doxorubicin (DOXIL) in soft tissue sarcoma-bearing rats.

It has previously been demonstrated in the setting of an isolated limb perfusion that application of high-dose TNF-alpha in combination with chemotherapy (melphalan, doxorubicin) results in strong synergistic antitumor effects in both the clinical and preclinical settings. In this study, we demonstrate that systemic administration of low-dose TNF-alpha augments the antitumor activity of a liposomal formulation of doxorubicin (DOXIL(R)). Addition of TNF-alpha to a DOXIL(R) regimen, which by itself induced some tumor growth delay, resulted in massive necrosis and regression of tumors. Furthermore, we could demonstrate a significant increase of liposomal drug in the tumor tissue when TNF-alpha had been co-administered. Administration of TNF-alpha augmented DOXIL(R) accumulation only after repeated injections, whereas accumulation of free doxorubicin was not affected by TNF-alpha. Drug levels in the tumor interstitium appeared crucial as intracellular levels of free or liposome-associated doxorubicin were not increased by TNF-alpha. Therefore, we hypothesize that low-dose TNF-alpha augments leakage of liposomal drug into the tumor interstitium, explaining the observed improved antitumor effects. Regarding the effects of systemic administration of low doses of TNF-alpha, these findings may be important for enhanced tumor targeting of various liposomal drug formulations.

TNF-alpha augments intratumoural concentrations of doxorubicin in TNF-alpha-based isolated limb perfusion in rat sarcoma models and enhances anti-tumour effects.

We have shown previously that isolated limb perfusion (ILP) in sarcoma-bearing rats results in high response rates when melphalan is used in combination with tumour necrosis factor alpha (TNF-alpha). This is in line with observations in patients. Here we show that ILP with doxorubicin in combination with TNF-alpha has comparable effects in two different rat sarcoma tumour models. The addition of TNF-alpha exhibits a synergistic anti-tumour effect, resulting in regression of the tumour in 54% and 100% of the cases for the BN175-fibrosarcoma and the ROS-1 osteosarcoma respectively. The combination is shown to be mandatory for optimal tumour response. The effect of high dose TNF-alpha on the activity of cytotoxic agents in ILP is still unclear. We investigated possible modes by which TNF-alpha could modulate the activity of doxorubicin. In both tumour models increased accumulation of doxorubicin in tumour tissue was found: 3.1-fold in the BN175 and 1.8-fold in the ROS-1 sarcoma after ILP with doxorubicin combined with TNF-alpha in comparison with an ILP with doxorubicin alone. This increase in local drug concentration may explain the synergistic anti-tumour responses after ILP with the combination. In vitro TNF-alpha fails to augment drug uptake in tumour cells or to increase cytotoxicity of the drug. These findings make it unlikely that TNF-alpha directly modulates the activity of doxorubicin in vivo. As TNF-alpha by itself has no or only minimal effect on tumour growth, an increase in local concentrations of chemotherapeutic drugs might well be the main mechanism for the synergistic anti-tumour effects.

Tumour necrosis factor alpha increases melphalan concentration in tumour tissue after isolated limb perfusion.

Several possible mechanisms for the synergistic anti-tumour effects between tumour necrosis factor alpha (TNF-alpha) and melphalan after isolated limb perfusion (ILP) have been presented. We found a significant sixfold increase in melphalan tumour tissue concentration after ILP when TNF-alpha was added to the perfusate, which provides a straightforward explanation for the observed synergism between melphalan and TNF-alpha in ILP.

Prerequisites for effective isolated limb perfusion using tumour necrosis factor alpha and melphalan in rats.

An isolated limb perfusion (ILP) model using soft tissue sarcoma-bearing rats was used to study prerequisites for an effective ILP, such as oxygenation of the perfusate, temperature of the limb, duration of the perfusion and concentration of tumour necrosis factor (TNF). Combination of 50 microg TNF and 40 microg melphalan demonstrated synergistic activity leading to a partial and complete response rate of 71%. In comparison to oxygenated ILP, hypoxia was shown to enhance anti-tumour activity of melphalan alone and TNF alone but not of their combined use. Shorter perfusion times decreased anti-tumour responses. At a temperature of 24-26 degrees C, anti-tumour effects were lost, whereas temperatures of 38-39 degrees C or 42-43 degrees C resulted in higher response rates. However, at 42-43 degrees C, local toxicity impaired limb function dramatically. Synergy between TNF and melphalan was lost at a dose of TNF below 10 microg in 5 ml perfusate. We conclude that the combination of TNF and melphalan has strong synergistic anti-tumour effects in our model, just as in the clinical setting. Hypoxia enhanced activity of melphalan and TNF alone but not the efficacy of their combined use. For an optimal ILP, minimal perfusion time of 30 min and minimal temperature of 38 degrees C was mandatory. Moreover, the dose of TNF could be lowered to 10 microg per 5 ml perfusate, which might allow the use of TNF in less leakage-free or less inert perfusion settings.