Synergistic antitumour effect of recombinant human tumour necrosis factor alpha with melphalan in isolated limb perfusion in the rat

Cancer immunotherapy: A comprehensive appraisal of its modes of application

Conventional cancer treatments such as chemotherapy and radiation therapy have reached their therapeutic potential, leaving a gap for developing more effective cancer therapeutics. Cancer cells evade the immune system using various mechanisms of immune tolerance, underlying the potential impact of immunotherapy in the treatment of cancer. Immunotherapy includes several approaches such as activating the immune system in a cytokine-dependent manner, manipulating the feedback mechanisms involved in the immune response, enhancing the immune response via lymphocyte expansion and using cancer vaccines to elicit long-lasting, robust responses. These techniques can be used as monotherapies or combination therapies. The present review describes the immune-based mechanisms involved in tumor cell proliferation and maintenance and the rationale underlying various treatment methods. In addition, the present review provides insight into the potential of immunotherapy used alone or in combination with various types of therapeutics.

Unleashing endogenous TNF-alpha as a cancer immunotherapeutic

Tumor necrosis factor (TNF)-alpha was originally identified in the 1970s as the serum mediator of innate immunity capable of inducing hemorrhagic necrosis in tumors. Today, a wide spectrum of biological activities have been attributed to this molecule, and clinical translation has mainly occurred not in using it to treat cancer, but rather to inhibit its effects to treat autoimmunity. Clinical trials utilizing systemic TNF-alpha administration have resulted in an unacceptable level of toxicities, which blocked its development. In contrast, localized administration of TNF-alpha in the form of isolated limb perfusion have yielded excellent results in soft tissue sarcomas. Here we describe a novel approach to leveraging the potent antineoplastic activities of TNF-alpha by enhancing activity of locally produced TNF-alpha through extracorporeal removal of soluble TNF-alpha receptors. Specifically, it is known that cancerous tissues are infiltrated with monocytes, T cells, and other cells capable of producing TNF-alpha. It is also known that tumors, as well as cells in the tumor microenvironment produce soluble TNF-alpha receptors. The authors believe that by selectively removing soluble TNF-alpha receptors local enhancement of endogenous TNF-alpha activity may provide for enhanced tumor cell death without associated systemic toxicities.

Isolated hepatic perfusion: principles and results

INTRODUCTION

Isolated hepatic perfusion allows the delivery of high dose chemotherapy while decreasing extra-hepatic toxicity, and is used mainly for patients with surgically unresectable liver tumors.

PRINCIPLES

Vascular exclusion of the liver is performed after obtaining satisfactory hemodynamic tolerance, occasionally after cavocaval shunt and/or porto-systemic shunt. Perfusion entry can be arterial and/or portal while the exit is portal or caval. The perfusion circuit can be open or closed, using a circulation pump with or without oxygenation. The chemotherapy regimens used are high dose melphalan (with or without TNF-alpha), oxaliplatin, cisplatin and mitomycin, sometimes associated with moderate hyperthermia. The duration of perfusion ranges between 30 and 90 minutes according to the different protocols used. A percutaneous technique with incomplete liver vascular exclusion is also possible.

RESULTS

The larger series in the literature show a response rate (partial or complete stabilization) between 60 and 80%, with approximately 5% complete morphologic responses. Morbidity and mortality are 40 and 5%, respectively, including specific morbidity related to the perfusion procedure as well as to chemotherapy.

CONCLUSION

Chemotherapy delivered through isolated hepatic perfusion is a new therapeutic alternative, still under development, and can be proposed to patients with surgically unresectable primary or secondary liver tumors within clinical trials. These results seem to be promising, but are still associated with a non-negligible morbidity rate.

Recent trends and future perspectives in isolated hepatic perfusion in the treatment of liver tumors

Isolated hepatic perfusion (IHP) involves a method of complete vascular isolation of the liver to enable treatment of liver tumors with high drug doses without systemic toxicity. Recent clinical studies have mainly employed IHP with melphalan with or without tumor necrosis factor-alpha and mild hyperthermia. The results of these studies demonstrate that high response and survival rates can be achieved with IHP. The current status, recent developments and future perspectives of IHP are discussed in this review.

TNF-α Polymorphisms in Juvenile Idiopathic Arthritis: Which Potential Clinical Implications?

Whether tumor necrosis factor alpha (TNF-α) gene polymorphisms (SNPs) influence disease susceptibility and treatment of patients with juvenile idiopathic arthritis (JIA) is presently uncertain. TNF-α is one of the most important cytokine involved in JIA pathogenesis. Several single nucleotide polymorphisms (SNPs) have been identified within the region of the TNF-α gene but only a very small minority have proven functional consequences and have been associated with susceptibility to JIA. An association between some TNF-α SNPs and adult rheumatoid arthritis (RA) susceptibility, severity and clinical response to anti-TNF-α treatment has been reported. The most frenquetly studied TNF-α SNP is located at -308 position, where a substitution of the G allele with the rare A allele has been found. The presence of the allele -308A is associated to JIA and to a poor prognosis. Besides, the -308G genotype has been associated with a better response to anti-TNF-α therapy in JIA patients, confirming adult data. Psoriatic and oligoarticular arthritis are significantly associated to the -238 SNP only in some works. Studies considering other SNPs are conflicting and inconclusive. Large scale studies are required to define the contribution of TNF-α gene products to disease pathogenesis and anti-TNF-α therapeutic efficacy in JIA.

Reliable establishment of human sarcoma xenografts in the nude rat

Purpose. The ability to establish consistent human tumor xenografts in experimental animals is a crucial part of preclinical investigations.The goal of this study was to develop a method of establishing a human tumor xenograft in the leg of a nude rat for evaluation of new surgical and molecular methods of treatments of human extremity sarcoma.

Methods and results. Initial attempts to produce sarcoma nodules by subcutaneous injection of a human leiomyosarcoma tumor cell suspension (SKLMS-1) resulted in tumor nodule formation in only four of 10 sites (40%).The xenograft method was modified to include younger nude rats of a different source and substrain (HSD:rnu/rnu, 5–9 weeks old), treated with 500 cGy whole-body irradiation, and the transplantation of tumor cells or small tumor fragments which had been embedded in Matrigel.These changes improved the tumor take rate per site to 52/52 (100%).Tumor nodules demonstrated rapid and progressive growth and histological features consistent with the original human sarcoma.

Discussion. Successful human leiomyosarcoma establishment in these nude rats permits the investigation of sarcoma biology and treatment with surgical procedures for which a mouse model would be inadequate. In this study we identified modifications in technique which enhanced the xenografting of a leiomyosarcoma cell line in nude rats; these techniques may increase tumor take rates for other tumor types as well.

Locoregional intravascular viral therapy of cancer: precision guidance for Paris's arrow?

Viral therapy of cancer includes strategies such as viral transduction of tumour cells with 'suicide genes', using viral infection to trigger immune-mediated tumour cell death and using oncolytic viruses for their direct anti-tumour action. However, problems still remain in terms of adequate viral delivery to tumours. A role is also emerging for single-organ isolation and perfusion. Having begun with the advent of isolated limb perfusion for extremity malignancy, experimental systems have been developed for the perfusion of other organs, particularly the liver, kidneys and lungs. These are beginning to be adopted into clinical treatment pathways. The combination of these two modalities is potentially significant. Locoregional perfusion increases the exposure of tumour cells to viral agents. In addition, the avoidance of systemic elimination through the immune and reticulo-endothelial systems should provide a mechanism for increased transduction/infection of target cells. The translation of laboratory research to clinical practice would occur within the context of perfusion programmes, which are already established in the clinic. Many of these programmes include the use of vasoactive cytokines such as tumour necrosis factor-alpha, which may have an effect on viral uptake. Evidence of activation of specific anti-tumour immunological responses by intratumoural and other existing methods of viral administration raises the intriguing possibility of a locoregional therapy, with the ability to affect distant sites of disease. In this review, we examined the state of the literature in this area and summarized current findings before indicating likely areas of continuing interest.

Activated CD4+ T cells enhance radiation effect through the cooperation of interferon-gamma and TNF-alpha

Background

Approaches that enhance radiation effect may lead to improved clinical outcome and decrease toxicity. Here we investigated whether activated CD4+ T cells (aCD4) can serve as an effective radiosensitizer.

Methods

CD4+ T cells were activated with anti-CD3 and anti-CD28 mAbs. Hela cells were presensitized with aCD4 or conditioned supernatant (aCD4S) or recombinant cytokines for 2 days, followed γ-irradiation. The treated cells were cultured for an additional 2 to 5 days for cell proliferation, cell cycle, and western blot assays. For confirmation, other cancer cell lines were also used.

Results

Presensitization of tumor cells with aCD4 greatly increased tumor cell growth inhibition. Soluble factors secreted from activated CD4⁺ T cells were primarily responsible for the observed effect. IFN-γ seemed to play a major role. TNF-α, though inactive by itself, significantly augmented the radiosensitizing activity of IFN-γ. aCD4S, but not IFN-γ or IFN-γ/TNF-α combination, was found to enhance the γ-irradiation-induced G2/M phase arrest. Bax expression was highly upregulated in Hela cells presensitized with aCD4S followed by γ-irradiation. The radio-sensitizing activity of aCD4 is not uniquely observed with Hela cell line, but also seen with other cancer cell lines of various histology.

Conclusions

Our findings suggest possible molecular and cellular mechanisms that may help explain the radio-sensitization effect of activated lymphocytes, and may provide an improved strategy in the treatment of cancer with radiotherapy.

TNF-alpha and its inhibitors in cancer

Tumor necrosis factor (TNF)-alpha is implicated in the same time in apoptosis and in cell proliferation. TNF-alpha not only acts as pro-inflammatory cytokine conducing to wide spectrum of human diseases including inflammatory diseases, but can also induce tumor development. The molecular mechanisms of TNF-alpha functions have been intensively investigated. In this review we covered TNF-alpha, the molecule, its signaling pathway, and its therapeutic functions. We provide a particular insight in its paradoxical role in tumor promotion and in its use as anti-tumor agent. This review considers also the recent findings regarding TNF-alpha inhibitors, their pharmacokinetics, and their pharmacodynamics. Six TNF-alpha inhibitors have been considered here: Infliximab, Adalimumab, Golimumab, CDP870, CDP571, Etanercept, and Thalidomide. We discussed the clinical relevance of their functions in treatment of several diseases such as advanced inflammatory rheumatic and bowel disease, with a focus in cancer treatment. Targeting TNF-alpha by these drugs has many side effects like malignancies development, and the long-term sequels are not very well explored. Their efficacy and their safety were discussed, underscoring the necessity of close patients monitoring and of their caution use.

Tumor necrosis factor-mediated interactions between inflammatory response and tumor vascular bed

Solid tumor therapy with chemotherapeutics greatly depends on the efficiency with which drugs are delivered to tumor cells. The typical characteristics of the tumor physiology promote but also appose accumulation of blood-borne agents. The leaky tumor vasculature allows easy passage of drugs. However, the disorganized vasculature causes heterogeneous blood flow, and together with the often-elevated interstitial fluid pressure, this state results in poor intratumoral drug levels and failure of treatment. Manipulation of the tumor vasculature could overcome these barriers and promote drug delivery. Targeting the vasculature has several advantages. The endothelial lining is readily accessible and the first to be encountered after systemic injection. Second, endothelial cells tend to be more stable than tumor cells and thus less likely to develop resistance to therapy. Third, targeting the tumor vasculature can have dual effects: (i) manipulation of the vasculature can enhance concomitant chemotherapy, and (ii) subsequent destruction of the vasculature can help to kill the tumor. In particular, tumor necrosis factor alpha is studied. Its action on solid tumors, both directly through tumor cell killing and destruction of the tumor vasculature and indirectly through manipulation of the tumor physiology, is complex. Understanding the mechanism of TNF and agents with comparable action on solid tumors is an important focus to further develop combination immunotherapy strategies.

Drug selection in isolated hepatic perfusion for nonresectable liver tumors: recent trends and perspectives

Isolated hepatic perfusion (IHP) involves a method of complete vascular isolation of the liver to take the advantage of directed intensive chemotherapy that has minimal systemic toxicity. Recent clinical studies mainly employed melphalan with or without tumor necrosis factor alpha (TNF-α), or with hyperthermia in IHP. The results of these studies showed that higher response rates and survival rates could be achieved by IHP than by traditional therapeutics for non-resectable liver tumors. In this article, we discussed the current status, recent developments and future perspectives of drug selection in IHP.

IL-27-mediated activation of natural killer cells and inflammation produced antitumour effects for human oesophageal carcinoma cells

Interleukin IL-27, composed of p28 and EBV-induced gene 3 subunits, has diverse functions in enhancing cell-mediated immunity and silencing the immunity. We examined whether forced expression of the p28-linked EBI3 gene in human oesophageal carcinoma cells (Eca109) produced antitumour effects in a T cell-defective condition. Tumour growth of Eca109 cells expressing IL-27 (Eca109/IL-27) was retarded in nude mice compared with parental and vector DNA-transduced tumours and survival of the mice inoculated with Eca109/IL-27 cells was prolonged. Expression of the tumour necrosis factor-alpha, IL-1beta and IL-6 genes was up-regulated in Eca109/IL-27 tumour specimens while the tumours remained small in size but the increased transcription was subsequently down-regulated in enlarged tumours. Spleen cells from mice-bearing Eca109/IL-27 tumours produced interferon-gamma and showed YAC-1-targeted cytotoxic activities greater than those of mice inoculated with parental or vector DNA-transducer tumours. Numbers of DX5+CD69+ natural killer cells in spleen of mice-bearing Eca109/IL-27 tumours and those of CD31+ cells within Eca109/IL-27 tumours remained the same as found in mice-bearing parental or vector DNA-transduced tumours. These data collectively suggest that the IL-27-mediated antitumour effects produced in a mature T cell-defective condition were attributable to enhanced interferon-gamma production and natural killer activities.

Laboratory models of regional chemotherapy

Development of new treatment strategies and agents is a difficult and costly matter in oncology. Routinely drugs are tested in vitro on tumor cells which, however, may have limited predictive value for their activity in patients. Also, the pharmacokinetic behavior, intratumoral distribution, as well as toxic side effects, binding to other compounds and stability of an agent are very important in determining activity in the patient. More so, development and evaluation of surgical delivery methods, i.e. regional treatment strategies, cannot be tested in cell systems. Therefore animal models are crucial for the development of regional chemotherapy methodologies. To allow translation of the animal data to patients it is important that the animal model closely mimics the clinical setting as for instance is achieved with isolated limb perfusion. However, animal models remain limited in their use, as eventually the efficacy of the approach may be different in animals compared to patients. Here we describe the use of animal models for regional treatment of solid tumors.

Adenovirally delivered tumor necrosis factor-alpha improves the antiglioma efficacy of concomitant radiation and temozolomide therapy

PURPOSE

Treatment of malignant glioma involves concomitant temozolomide and ionizing radiation (IR). Nevertheless, overall patient survival remains poor. This study was designed to evaluate if addition of Ad.Egr-tumor necrosis factor (TNF), a replication defective adenovector encoding a cDNA for TNF-alpha, to temozolomide and IR can improve overall antiglioma effect.

EXPERIMENTAL DESIGN

The efficacy of combination treatment with Ad.Egr-TNF, IR, and temozolomide was assessed in two glioma xenograft models. Animal toxicity and brain histopathology after treatment were also examined. In addition, in an attempt to explain the antitumor interaction between these treatments, the activation status of the transcription factor nuclear factor-kappaB was examined.

RESULTS

Triple therapy (Ad.Egr-TNF, IR, and temozolomide) leads to significantly increased survival in mice bearing glioma xenografts compared with dual treatment. Fifty percent of animals treated with the triple regimen survive for >130 days. Pathologic examination shows that triple therapy leads to a complete response with formation of a collagenous scar. No significant change in myelination pattern is noted after triple therapy, compared with any double treatment. Treatment of intracranial glioma bearing mice with Ad.Egr-TNF and IR leads to cachexia and poor feeding that does not improve, whereas triple therapy results in less toxicity, which improves over 21 days. Both Ad.Egr-TNF and IR activate nuclear factor-kappaB, and temozolomide inhibits this activity in an inhibitor of kappaBalpha (IkappaBalpha)-independent manner.

CONCLUSION

This work shows that the addition of adenoviral TNF-alpha gene delivery to temozolomide and IR significantly improves antiglioma efficacy and illustrates a potential new treatment regimen for use in patients with malignant glioma.

TNF potentiates anticancer activity of bortezomib (Velcade) through reduced expression of proteasome subunits and dysregulation of unfolded protein response

Bortezomib (Velcade) exploits proteasome inhibition as a unique mechanism of anticancer activity. The effectiveness of bortezomib is, however, limited, therefore, the search for therapeutic regimens combining bortezomib with other agents. In the present work we demonstrate enhanced anticancer activity of bortezomib by its combination with tumor necrosis factor (TNF) in the experimental model of C-26 colon carcinoma in mice. This interaction likely relies on the induction of a dysregulated response to ER stress, leading to apoptosis of cancer cells, evidenced by caspase-3 cleavage, p53 accumulation as well as increased SAPK/JNK phosphorylation. ER stress induced by the combination of TNF and bortezomib is corroborated by upregulation of BiP, PDI and calnexin as well as cleavage of caspase-12; however, in contrast to the classic pathway, it is also associated with decreased phosphorylation of eIF2 alpha and prevention of XBP-1 splicing. TNF prevented the upregulation of Hsp27 induced by bortezomib, which may contribute to enhanced ER stress. Moreover, TNF interfered with bortezomib-induced upregulation of distinct subunits of the 26S proteasome. Bortezomib concentration used in this study was not sufficient to prevent TNF from inducing nuclear translocation of p65/RelA; however, the combination of both agents reduced total p65/RelA levels. Combined treatment of tumor-bearing mice with bortezomib and TNF not only inhibited tumor growth but also significantly prolonged animal survival. Therefore, combination of bortezomib with TNF is an attractive option for further clinical studies.

Survival of TNF toxicity: dependence on caspases and NO

Tumor necrosis factor (TNF) is an endogenous pro-inflammatory cytokine, implicated in pathologies such as rheumatoid arthritis and septic shock. It was originally discovered as a factor with extraordinary antitumor activity, but its shock-inducing properties still prevent its systemic use in cancer. Clinical trials revealed hypotension as the major dose-limiting factor of TNF toxicity. When administered to mice, TNF provokes a lethal shock syndrome, where cardiovascular collapse is centrally orchestrated by nitric oxide (NO). Nevertheless, NO synthase (NOS) inhibition in animal models and septic shock patients could not improve and even aggravated outcome, suggesting a bivalent role for NO. Lymphocyte and enterocyte apoptosis has been described in septic, endotoxemic, or TNF-treated animals, as well as in septic patients. In this review, we describe our recent studies on the role of NO and caspases in TNF-induced shock in mice. In summary, we have found that both NO and caspases may exert unexpected and dual functions during TNF shock. Whereas excessive NO production provokes lethal hypotension, it also has an important anti-oxidant function, protecting organs from oxidative stress and lipid peroxidation. In addition, our results also indicate that caspases may exert an important endogenous negative feedback on oxidative stress as well.

Early destruction of tumor vasculature in tumor necrosis factor-alpha-based isolated limb perfusion is responsible for tumor response

Addition of high-dose tumor necrosis factor-alpha to melphalan-based isolated limb perfusion enhances anti-tumor effects impressively. Unfortunately, the mechanism of action of tumor necrosis factor-alpha is still not fully understood. Here, we investigated the effects of tumor necrosis factor-alpha on the tumor microenvironment and on secondary immunological events during and shortly after isolated limb perfusion in soft-tissue sarcoma-bearing rats. Already during isolated limb perfusion, softening of the tumor was observed. Co-administration of tumor necrosis factor-alpha in the isolated limb perfusion with melphalan induced a six-fold enhanced drug accumulation of melphalan in the tumor compared with isolated limb perfusion with melphalan alone. In addition, directly after perfusion with tumor necrosis factor-alpha plus melphalan, over a time-frame of 30 min, vascular destruction, erythrocyte extravasation and hemorrhage was detected. Interstitial fluid pressure and pH in the tumor, however, were not altered by tumor necrosis factor-alpha and no clear immune effects, cellular infiltration or cytokine expression were observed. Taken together, these results indicate that tumor necrosis factor-alpha induces rapid damage to the tumor vascular endothelial lining resulting in augmented drug accumulation. As other important parameters were not changed (e.g. interstitial fluid pressure and pH), we speculate that the tumor vascular changes, and concurrent hemorrhage and drug accumulation are the key explanations for the observed synergistic anti-tumor response.

TNF-alpha in cancer treatment: molecular insights, antitumor effects, and clinical utility

Tumor necrosis factor alpha (TNF-alpha), isolated 30 years ago, is a multifunctional cytokine playing a key role in apoptosis and cell survival as well as in inflammation and immunity. Although named for its antitumor properties, TNF has been implicated in a wide spectrum of other diseases. The current use of TNF in cancer is in the regional treatment of locally advanced soft tissue sarcomas and metastatic melanomas and other irresectable tumors of any histology to avoid amputation of the limb. It has been demonstrated in the isolated limb perfusion setting that TNF-alpha acts synergistically with cytostatic drugs. The interaction of TNF-alpha with TNF receptor 1 and receptor 2 (TNFR-1, TNFR-2) activates several signal transduction pathways, leading to the diverse functions of TNF-alpha. The signaling molecules of TNFR-1 have been elucidated quite well, but regulation of the signaling remains unclear. Besides these molecular insights, laboratory experiments in the past decade have shed light upon TNF-alpha action during tumor treatment. Besides extravasation of erythrocytes and lymphocytes, leading to hemorrhagic necrosis, TNF-alpha targets the tumor-associated vasculature (TAV) by inducing hyperpermeability and destruction of the vascular lining. This results in an immediate effect of selective accumulation of cytostatic drugs inside the tumor and a late effect of destruction of the tumor vasculature. In this review, covering TNF-alpha from the molecule to the clinic, we provide an overview of the use of TNF-alpha in cancer starting with molecular insights into TNFR-1 signaling and cellular mechanisms of the antitumor activities of TNF-alpha and ending with clinical response. In addition, possible factors modulating TNF-alpha actions are discussed.

Addition of low-dose tumor necrosis factor-alpha to systemic treatment with STEALTH liposomal doxorubicin (Doxil) improved anti-tumor activity in osteosarcoma-bearing rats

Improved efficacy of Doxil (STEALTH liposomal doxorubicin) compared to free doxorubicin has been demonstrated in the treatment of several tumor types. We have shown that addition of low-dose tumor necrosis factor (TNF) to systemic Doxil administration dramatically improved tumor response in the highly vascularized rat soft tissue sarcoma BN175. Whether a similar enhanced efficacy can be achieved in less vascularized tumors is uncertain. We therefore examined the effect of systemic administration of Doxil in combination with low-dose TNF in intermediate vascularized osteosarcoma-bearing rats (ROS-1). Small fragments of the osteosarcoma were implanted s.c. in the lower limb. Treatment was started when the tumors reached an average diameter of 1 cm. Rats were treated with five i.v. injections at 4-day intervals with Doxil or doxorubicin and TNF. Systemic treatment with Doxil resulted in a better tumor growth delay than free doxorubicin, but with progressive diseases in all animals. The 3.5-fold augmented accumulation of Doxil compared to free doxorubicin presumably explains the enhanced tumor regression. Addition of low-dose TNF augmented the anti-tumor activity of Doxil, although no increased drug uptake was found compared to Doxil alone. In vitro studies showed that ROS-1 is sensitive to TNF, but systemic treatment with TNF alone did not result in a tumor growth delay. Furthermore, we demonstrated that treatment with Doxil alone or with TNF resulted in massive coagulative necrosis of tumor tissue. In conclusion, combination therapy of Doxil and low-dose TNF seems attractive for the treatment of highly vascularized tumors, but also of intermediate vascularized tumors like the osteosarcoma.

Isolated limb perfusion for melanoma patients—a review of its indications and the role of tumour necrosis factor-α

AIMS

The treatment of melanoma in-transit metastases (IT-mets) can vary widely and is dependant on the size and the number of the lesions. When multiple, large lesions exist, isolated limb perfusion (ILP) has established itself as an attractive treatment option with high response rates.

METHODS

Review on the various methods of treatment of melanoma in-transit metastases, with a focus on isolated limb perfusion. A Medline based literature search was performed for articles relating to this topic. Additional original papers were obtained from citations in those identified by the initial search. Indications and results are discussed and the extra value of tumour necrosis factor (TNF) is evaluated.

RESULTS

ILP with Melphalan results in complete response rates of 40-82% and showed to be 54% in a large retrospective meta-analysis. The addition of TNF can improve these completes response rates (59-85%) and although no data from randomized controlled trials are available, it seems of particular value in large, bulky lesions or in patients with recurrent disease after previous ILP.

CONCLUSIONS

TNF-based ILP has earned a permanent place in the treatment of patients with melanoma IT-mets. In patients with a high tumour burden, TNF-based ILP is the most efficacious procedure to obtain local control and achieve limb salvage.

Synergistic antitumor response of interleukin 2 with melphalan in isolated limb perfusion in soft tissue sarcoma-bearing rats

The cytokine interleukin 2 (IL-2) is a mediator of immune cell activation with some antitumor activity, mainly in renal cell cancer and melanoma. We have previously shown that tumor necrosis factor (TNF)-alpha has strong synergistic antitumor activity in combination with chemotherapeutics in the isolated limb perfusion (ILP) setting based on a TNF-mediated enhanced tumor-selective uptake of the chemotherapeutic drug followed by a selective destruction of the tumor vasculature. IL-2 can cause vascular leakage and edema and for this reason we examined the antitumor activity of a combined treatment with IL-2 and melphalan in our well-established ILP in soft tissue sarcoma-bearing rats (BN175). ILP with either IL-2 or melphalan alone has no antitumor effect, but the combination of IL-2 and melphalan resulted in a strong synergistic tumor response, without any local or systemic toxicity. IL-2 enhanced significantly melphalan uptake in tumor tissue. No signs of significant vascular damage were detected to account for this observation, although the tumor sections of the IL-2- and IL-2 plus melphalan-treated animals revealed scattered extravasation of erythrocytes compared with the untreated animals. Clear differences were seen in the localization of ED-1 cells, with an even distribution in the sham, IL-2 and melphalan treatments, whereas in the IL-2 plus melphalan-treated tumors clustered ED-1 cells were found. Additionally, increased levels of TNF mRNA were found in tumors treated with IL-2 and IL-2 plus melphalan. These observations indicate a potentially important role for macrophages in the IL-2-based perfusion. The results in our study indicate that the novel combination of IL-2 and melphalan in ILP has synergistic antitumor activity and may be an alternative for ILP with TNF and melphalan.

Liposomal Cytokines in the Treatment of Infectious Diseases and Cancer

Despite of the demonstrated activity of cytokines in vitro, their use in the clinical setting is often disappointing. Cytokine-related toxicity seriously limits optimal use in vivo. In addition, rapid degradation and excretion, neutralization and binding to receptors, or metabolization of the molecule results in a short half-life in serum when injected intravenously. As the dose-response curve of cytokines is relatively steep, outcome greatly benefits from improved delivery and bioavailability. One way to improve the pharmacokinetics of cytokines after systemic application is encapsulation in liposomes. An advantage of liposomes is that the encapsulated drug is protected from (rapid) degradation and excretion, and it eliminates the binding to neutralizing antibodies or (soluble) receptors. Moreover, liposomes can be tailored in such a way that they exhibit favorable pharmacokinetics, i.e., increased serum half-life and improved targeting to tissues or cells of interest. In this chapter, the use of liposomal cytokines in the treatment of cancer and infectious disease is discussed.

Construction and validation of a microprocessor controlled extracorporal circuit in rats for the optimization of isolated limb perfusion

Although a few experimental approaches to isolated limb perfusion (ILP) are described in the literature, none of these animal models mimics the clinical perfusion techniques adequately to improve the technique of ILP on the basis of valid preclinical data. Therefore, we developed an ILP setup in rats allowing online monitoring of essential perfusion parameters such as temperature (in perfusate, various tissues, and rectum), pH (perfusate), perfusion pressure, and O(2) concentration (in perfusate, tissue), by a tailor-made data acquisition system. This setup permits close supervision of vital parameters during ILP. Various interdependencies, concerning the flow rate and the pressure of perfusate as well as tissue oxygenation were registered. For the measurement of pO(2) values in the perfusate and in different regions of the perfused hind limb, a novel type of microoptode based on quenching of a fluorescent dye was devised. Stable normothermic (37 degrees C) perfusion conditions were maintained at a constant perfusion pressure in the range of 40-60 mm Hg by administration of the spasmo lytic moxaverine (0.5 mg/mL of perfusate as initial dose) at a perfusate flow rate of 0.5 mL/min for 60 min. At the end of an ILP, there were no signs of tissue damage, neither concerning laboratory data (K(+), myoglobin, creatine kinase, lactic dehydrogenase) nor histopathological criteria. The reported ILP model is not only well suited to investigate the effects of hyperthermia but also to assess the efficacy of new antineoplastic approaches, when nude rats, bearing human tumours in the hind limbs, are used.

Synergistic Antitumor Activity of Histamine Plus Melphalan in Isolated Limb Perfusion: Preclinical Studies

BACKGROUND

We have previously shown how tumor response of isolated limb perfusion (ILP) with melphalan was improved when tumor necrosis factor alpha (TNF-alpha) was added. Taking into account that other vasoactive drugs could also improve tumor response to ILP, we evaluated histamine (Hi) as an alternative to TNF-alpha.

METHODS

We used a rat ILP model to assess the combined effects of Hi and melphalan (n = 6) on tumor regression, melphalan uptake (n = 6), and tissue histology (n = 2) compared with Hi or melphalan alone. We also evaluated the growth of BN-175 tumor cells as well as apoptosis, necrosis, cell morphology, and paracellular permeability of human umbilical vein endothelial cells (HUVECs) after Hi treatment alone and in combination with melphalan.

RESULTS

The antitumor effect of the combination of Hi and melphalan in vivo was synergistic, and Hi-dependent reduction in tumor volume was blocked by H1 and H2 receptor inhibitors. Tumor regression was observed in 66% of the animals treated with Hi and melphalan, compared with 17% after treatment with Hi or melphalan alone. Tumor melphalan uptake increased and vascular integrity in the surrounding tissue was reduced after ILP treatment with Hi and melphalan compared with melphalan alone. In vitro results paralleled in vivo results. BN-175 tumor cells were more sensitive to the cytotoxicity of combined treatment than HUVECs, and Hi treatment increased the permeability of HUVECs.

CONCLUSIONS

Hi in combination with melphalan in ILP improved response to that of melphalan alone through direct and indirect mechanisms. These results warrant further evaluation in the clinical ILP setting and, importantly, in organ perfusion.

Isolated hepatic perfusion for the treatment of colorectal metastases confined to the liver: recent trends and perspectives

Isolated hepatic perfusion (IHP) involves a method of complete vascular isolation of the liver to allow treatment of liver tumours with toxic systemic doses. The recent clinical studies mainly employed IHP with melphalan with or without tumour necrosis factor-alpha (TNF-alpha) and mild hyperthermia. The results of these studies show that high response rates and high survival rates can be achieved by IHP. In this article, the current status, recent developments and future perspectives of IHP are discussed.

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.

Transcriptional Targeting of Adenovirally Delivered Tumor Necrosis Factor α by Temozolomide in Experimental Glioblastoma

Temozolomide is an oral alkylating agent shown to have modest efficacy in the treatment of glioblastoma multiforme. Tumor necrosis factor alpha (TNF-alpha) is a polypeptide cytokine with synergistic antitumor activity in combination therapy with alkylating agents. We investigated the combined use of Ad.Egr-TNF, a replication-defective adenoviral vector encoding the cDNA for TNF-alpha under the control of chemo-inducible elements of the egr1 gene promoter, and intraperitoneal temozolomide in an intracranial human malignant glioma model. In hind limb U87MG xenografts, temozolomide produced a 6.4-fold greater induction of TNF-alpha after infection with Ad.Egr-TNF compared with Ad.Egr-TNF alone at 96 hours (P < 0.02). TNF-alpha and temozolomide combination leads to a synergistic decrease in U87 cell viability at 72 hours compared with either treatment alone (P < 0.001). Median survival for animals treated with Ad.Egr-TNF alone, temozolomide alone, and Ad.Egr-TNF/temozolomide was 21, 28, and 74 days, respectively (P < 0.001 by log-rank). Flow cytometric assessment of apoptosis revealed a synergistic increase in U87 cell apoptosis in vitro at 72 hours (P < 0.05), and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL) evaluation of tumor sections revealed significantly increased TUNEL-positive cells after combination treatment compared with either treatment alone (P < 0.05). In conclusion, combination treatment with transcriptionally activated intratumoral TNF-alpha and systemic temozolomide significantly prolongs survival in an experimental glioblastoma multiforme model.

Metaiodobenzylguanidine and hyperglycemia augment tumor response to isolated limb perfusion in a rodent model of human melanoma

BACKGROUND

Perfusate acidification with dilute hydrochloric acid augments tumor response rates in a rodent model of isolated limb perfusion (ILP). This study investigates the combination of metaiodobenzylguanidine (MIBG), a mitochondrial inhibitor, and systemic hyperglycemia as a strategy to selectively acidify tumors and thereby sensitize them to ILP.

METHODS

Human melanoma xenografts were implanted into the hind limbs of athymic rats. When tumors reached 12 to 15 mm in diameter, animals were randomized to ILP with or without melphalan, with or without systemic MIBG, and hyperglycemia of 485 +/- 35 mg/dL. Intratumoral pH was measured during MIBG and glucose treatment by using magnetic resonance spectroscopy.

RESULTS

MIBG at 30 mg/kg plus hyperglycemia decreased intracellular pH by.6 units and extracellular pH by.8 units. MIBG at 22.5 mg/kg plus hyperglycemia decreased intracellular and extracellular pH by.4 and.5 units, respectively. Tumor growth was unaffected by systemic MIBG and hyperglycemia alone. When MIBG at 30 mg/kg and hyperglycemia were combined with ILP, tumor growth was delayed for 33 days after control ILP and for 44 days after melphalan ILP. However, this dose of MIBG was complicated by a 40% mortality rate after ILP. MIBG at 22.5 mg/kg, in combination with MIBG in the perfusate, did not cause mortality and delayed tumor growth by 51 days after melphalan ILP.

CONCLUSIONS

MIBG and hyperglycemia improve tumor response rates after ILP in a rodent model of human melanoma. Selective tumor acidification with MIBG and hyperglycemia may offer added benefit to current regional perfusion strategies.

TNFalpha-based isolated perfusion for limb-threatening soft tissue sarcomas: state of the art and future trends

The management of limb-threatening soft tissue sarcomas has not yet been standardized. Although local disease control does not affect overall survival, amputation or highly mutilating surgery may be required, which impairs the patient's quality of life. Various neoadjuvant approaches have been proposed to allow limb-sparing surgery for these locally advanced tumors. With TNFalpha-based hyperthermic isolated limb perfusion, the majority of patients can be spared amputation, with acceptable rates of locoregional and systemic complications. As yet, no other available treatment seems to give comparable results when applied to limb-threatening soft tissue sarcomas. Nevertheless, several issues remain to be addressed, such as the type and dose of drugs, repeatability of the procedure, association with radiotherapy, further indications, and evaluation of response. The authors describe the principles underlying TNFalpha-based hyperthermic isolated limb perfusion, review the worldwide experience so far published, and discuss the above issues. The potential future developments of this locoregional therapeutic approach will also be reported.

Current uses of isolated limb perfusion in the clinic and a model system for new strategies

Isolated limb perfusion with melphalan is the treatment of choice for multiple (small) melanoma-in-transit metastases. The use of tumour necrosis factor alpha (TNFalpha) in isolated limb perfusion is successful for treatment of locally advanced limb soft-tissue sarcomas and other large tumours; this approach can avoid the need for amputation. TNFalpha was approved in Europe after a multicentre trial in patients with locally advanced soft-tissue sarcomas, deemed unresectable by an independent review committee; the response rate to isolated limb perfusion with TNFalpha plus melphalan was 76% and the limb was saved in 71% of patients. Moreover, the trial showed the efficacy of isolated limb perfusion of TNFalpha and melphalan against various other limb-threatening tumours such as skin cancers and drug-resistant bony sarcomas. Laboratory models of isolated limb perfusion have helped to elucidate mechanisms of action and to develop new treatment modalities. They have identified TNFalpha-mediated vasculotoxic effects on the tumour vasculature and have shown that addition of TNFalpha to the perfusate results in an increase of three to six times in uptake of melphalan or doxorubicin by tumours. New vasoactive drugs and new mechanisms of action are being discovered. Moreover, isolated limb perfusion is an effective modality for gene therapy mediated by an adenoviral vector. Various clinical phase I-II studies can be expected in the next few years.

A human melanoma xenograft in a nude rat responds to isolated limb perfusion with TNF plus melphalan

BACKGROUND

Isolated limb perfusion (ILP) with tumor necrosis factor-alpha (TNF) and melphalan for advanced extremity malignancies achieves significant complete response rates. To study molecular mechanisms underlying this response, a nude rat ILP model with a human melanoma xenograft was developed.

METHODS

NIH1286 human melanoma was grown subcutaneously in the hind limb of nude rats. Anesthetized rats underwent a 10-minute ILP via femoral vessels with hetastarch, heparin, and melphalan, TNF, or TNF plus melphalan. The tumors and ulcers were measured and viable tumor area was calculated. Post-ILP tumors were analyzed by electron microscopy for vascular damage and also by liquid chromatography atmospheric pressure chemical ionization tandem mass spectrometry (LC/APCI/MS/MS) for free melphalan levels. Colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-dephenyltetrazolium bromide (MTT) assays were performed on NIH1286 cells and human dermal microvascular endothelial cells (HDMVEC) to test for direct cytotoxicity to TNF and melphalan. Post-ILP tumors sections were also examined by electron microscopy.

RESULTS

The mean maximal decrease in viable tumor area after ILP for control, TNF, melphalan, and TNF + melphalan groups were 0%, 22 +/- 13%, 61 +/- 14%, and 100 +/- 0%, respectively. LC/APCI/MS/MS revealed no difference in the free tumor melphalan concentration between melphalan alone and TNF + melphalan groups. The percent cytotoxicity in MTT assays using TNF, melphalan, and TNF + melphalan against NIH1286 were 0%, 51-59%, and 74-81%, respectively, and against HDMVEC were 28%, 16-23%, and 6-13%, respectively. Electron microscopic analyses showed that addition of TNF to the perfusate caused erythrostasis in tumor blood vessels.

CONCLUSION

We developed a human melanoma nude rat ILP model with tumor responses very similar to the human ILP trials. This model will allow further investigation of the synergistic mechanism of TNF and melphalan in human melanoma in a preclinical setting, and extension of this study to current clinical trials.

The role of isolated limb perfusion for melanoma confined to the extremities

Isolated limb perfusion with Melphalan is the best treatment option to control symptomatic multiple small in-transit metastases. When lesions are bulky, Isolated Limb Perfusion (ILP) with Tumor Necrosis Factor (TNF) + Melphalan is superior as in soft tissue sarcoma. TNF changes the pathophysiology, greatly enhances the uptake of Melphalan and destructs selectively the vasculature of large tumors. To date, ILP is not indicated in an adjuvant setting.

Isolated limb perfusion in the management of locally advanced extremity soft tissue sarcoma

In conclusion, ILP is an interesting and important treatment option in the management of locally advanced extremity soft tissue sarcomas. Large medical centers, dealing with referrals and an important caseload of STS patients, should develop this treatment option and have it readily available to offer patients the best chances for limb salvage. In Europe, the success of TNF-based ILP has lead to the training, accreditation, and activation of TNF-based ILP programs in over 30 cancer centers since the approval of TNF for this indication in 1999. Thus, country by country centers for referral programs are established to deal with those categories of patients that can greatly benefit from the availability and integration of this treatment option in the STS treatment programs.

Isolated limb perfusion with tumor necrosis factor and melphalan for nonresectable sSewart-Treves lymphangiosarcoma

BACKGROUND

Cutaneous Stewart-Treves lymphangiosarcomas represent a rare group of tumors characterized by a high grade of vascularization and by localization in an extremity with lymphedema. The multifocality and the localization makes these tumors eligible for treatment with isolated limb perfusion (ILP). ILP with tumor necrosis factor (TNF) and melphalan is a safe and highly effective procedure that can achieve limb salvage in >or=80% of all patients with nonresectable extremity soft tissue sarcoma or melanoma.

METHODS

In 10 patients with multifocal Stewart-Treves lymphangiosarcoma of the extremities, 16 ILPs with TNF plus melphalan were performed. All patients would have been candidates for exarticulation of the extremity.

RESULTS

We observed an 87% overall response rate (complete and partial responses); one patient had a mixed response, and one patient did not respond to the therapy. In nine perfusions (56%), a complete response was achieved, and five perfusions (31%) resulted in a partial response. Limb salvage was achieved in eight patients (80%), with a mean follow-up duration of 34.8 months (range, 3 to >or=115 months). Regional toxicity was limited and systemic toxicity minimal to moderate, with no toxic deaths.

CONCLUSIONS

Multifocal Stewart-Treves lymphangiosarcomas in extremities with chronic lymphedema can be successfully treated by ILP with TNF and melphalan.

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.

Saturable dose-response relationships for melphalan in melanoma treatment by isolated limb infusion in the nude rat

Nude rats bearing melanomas on their hindlimbs were treated by isolated limb infusion (ILI) with increasing doses (7.5-400 microg/ml) of melphalan. The response of tumours to treatment at the end of the observation period was graded, according to diameter, as complete response (CR), partial response (PR), no change (NC) or progressive disease (PD). No linear relationship between the dose of melphalan and the tumour response was observed. All doses above a threshold of 15 microg/ml achieved a PR or CR. The achievement of CR was not related to increased dose. Two major implications arise from this work. Firstly, the typically two- to three-fold increase in cytotoxic drug concentration given in high dose chemotherapy compared with standard drug concentration may not be sufficient to produce the expected increase in tumour response and possibly survival, and the controversial results of high dose chemotherapy in different studies may thus be explained. Secondly, since an increase in melphalan dose above a certain threshold does not greatly increase tumour response, the use of combination therapies would seem to be more likely to be effective than increased chemotherapeutic drug doses in achieving better tumour responses.

Gene delivery from the E3 region of replicating human adenovirus: evaluation of the E3B region

Successful therapies for cancer need to deal with the complexity associated with the human tumor. Studies of tumor and viral biology have progressed to a point where replicating viruses are now being engineered as potential treatments for human cancers. The complex nature of human cancers dictates that successful treatments will require combination therapies. To this end, we have focused on developing the gene delivery capacity of the replicating adenovirus, using the non-essential E3 region transcription unit as a target site for therapeutic transgene insertions. Utilizing the endogenous expression machinery of the E3 region (promoter, splicing, polyA) we show that a therapeutic transgene, TNF, is efficiently expressed from the E3B region and with exclusive late gene expression kinetics. Potential clinical applications are discussed.

Isolated limb perfusion for extremity soft-tissue sarcomas, in-transit metastases, and other unresectable tumors: credits, debits, and future perspectives

Isolated limb perfusion (ILP) with melphalan is effective against melanoma in-transit metastases but has failed in the treatment of limb-threatening extremity sarcomas. Tumor necrosis factor-alpha (TNF) has changed this situation completely. Now, ILP with TNF + melphalan is a very successful treatment to prevent amputation. In a multicenter European trial, ILP with TNF + melphalan resulted in a 76% response rate and a 71% limb salvage rate in patients with limb-threatening soft-tissue sarcomas, deemed unresectable by independent review committees, leading to approval of TNF in Europe. We have also reported on the success of this regimen against bulky melanomas, multifocal skin cancers, and drug-resistant bony sarcomas. High-dose TNF destructs tumor vasculature, and, most importantly, it enhances tumor-selective drug uptake (ie, melphalan and doxorubicin) by threefold to sixfold. Similar synergy is observed in well-vascularized liver metastases after isolated hepatic perfusion with TNF and melphalan. New (vasoactive) drugs and mechanisms of action and interaction with chemotherapy are in development. ILP is also a promising treatment modality for adenoviral vector-mediated gene therapy. Many clinical phase I/II evaluations in ILP are now underway.

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.

Isolated limb perfusion for local gene delivery: efficient and targeted adenovirus-mediated gene transfer into soft tissue sarcomas

OBJECTIVE

To evaluate the potential of isolated limb perfusion (ILP) for efficient and tumor-specific adenovirus-mediated gene transfer in sarcoma-bearing rats.

SUMMARY BACKGROUND DATA

A major concern in adenovirus-mediated gene therapy in cancer is the transfer of genes to organs other than the tumor, especially organs with a rapid cell turnover. Adjustment of the vector delivery route might be an option creating tumor specificity in therapeutic gene expression.

METHODS

Rat hind limb sarcomas (5-10 mm) were transfected with recombinant adenoviruses. Intratumoral luciferase expression after ILP was compared with systemic administration, regional infusion, or intratumoral injection using a similar dose of adenoviruses carrying the luciferase marker gene. Localization studies using lacZ as a marker gene were performed to evaluate the intratumoral distribution of transfected cells after both ILP and intratumoral injection.

RESULTS

Intratumoral luciferase activity after ILP or intratumoral administration was significantly higher compared with regional infusion or systemic administration. After ILP, luciferase gene expression was minimal in extratumoral organs, whether outside or inside the isolated circuit. Localization studies demonstrated that transfection was confined to tumor cells lying along the needle track after intratumoral injection, whereas after ILP, lacZ expression was found in viable tumor cells and in the tumor-associated vasculature.

CONCLUSIONS

Using ILP, efficient and tumor-specific gene transfection can be achieved. The ILP technique might be useful for the delivery of recombinant adenoviruses carrying therapeutic gene constructs to enhance tumor control.

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.

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.