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

Anti-cancer effect of Rumex obtusifolius in combination with arginase/nitric oxide synthase inhibitors via downregulation of oxidative stress, inflammation, and polyamine synthesis

Cancer continues to be a leading cause of death worldwide, making the development of new treatment methods crucial in the fight against it. With cancer incidence rates increasing worldwide, ongoing research must focus on identifying new and effective ways to prevent and treat the disease. The combination of herbal extracts with chemotherapeutic agents has gained much interest as a novel strategy to combat cancer. Rumex obtusifolius L. is a wild plant known for its medicinal properties and is widely distributed worldwide. Our preclinical evaluations suggested that R. obtusifolius seed extracts possessed cancer-inhibiting properties and we also evaluated the beneficial effects of the arginase inhibitor NG-hydroxy-nor-L-arginine and nitric oxide inhibitor NG-nitro-L-arginine methyl ester in the treatment of breast cancer. The current study aimed to combine these observations and evaluate the antioxidant and antitumor properties of R. obtusifolius extracts alone and in combination with the arginase and nitric oxide synthase inhibitors. Metabolic characterization of the plant extract using a liquid chromatography/high-resolution mass spectrometry advanced system revealed the presence of 240 phenolic compounds many of which possess anticancer properties, according to the literature. In vitro studies revealed a significant cytotoxic effect of the R. obtusifolius extracts on the human colon (HT29) and breast cancer (MCF-7) cell lines. Thus, a new treatment approach of combining R. obtusifolius bioactive phytochemicals with the arginase and nitric oxide synthase inhibitors NG-nitro-L-arginine methyl ester and/or NG-hydroxy-nor-L-arginine, respectively, was proposed and could potentially be an effective way to treat breast cancer. Indeed, these combinations showed immunostimulatory, antiproliferative, antioxidant, anti-inflammatory, and antiangiogenic properties in a rat breast cancer model.

Anti-cancer effect of in vivo inhibition of nitric oxide synthase in a rat model of breast cancer

Increased expression of nitric oxide synthase (NOS) is associated with different cancers such as cervical, breast, lung, brain, and spinal cord. Inhibition of NOS activity has been suggested as potential tool to prevent breast cancer. The anti-tumor therapeutic effect of L-nitro arginine methyl ester (L-NAME), NOS inhibitor, using in vivo models is currently under investigation. We hypothesized that L-NAME will show an anti-tumor effect by delaying a progression of breast cancer via a modulation of cell death and proliferation, and angiogenesis. We used a novel model of anti-cancer treatment by the administration of L-NAME (30 mg/kg in a day, intraperitoneal) injected every third day for five weeks to rat model of 7,12-dimethylbenz[a]anthracene (DMBA)-induced breast tumor. Concentrations of nitrite anions, polyamines, malondialdehyde, NH₄⁺ levels, and arginase activity in the blood were decreased in DMBA + L-NAME-treated rats compared with DMBA rats. The mortality rates, tumor number, weight, and volume, as well as the histopathological grade of breast cancer were also significantly reduced. In addition, L-NAME treatment showed a delay in tumor formation, and in body weight compared with rats administrated only with DMBA. In conclusion, our data show that L-NAME is a promising anti-cancer agent to treat breast cancer, which can lead to development of anti-tumor therapeutic tools in future.

Gene Therapy of Chronic Limb-Threatening Ischemia: Vascular Medical Perspectives

A decade ago, gene therapy seemed to be a promising approach for the treatment of chronic limb-threatening ischemia, providing new perspectives for patients without conventional, open or endovascular therapeutic options by potentially enabling neo-angiogenesis. Yet, until now, the results have been far from a safe and routine clinical application. In general, there are two approaches for inserting exogenous genes in a host genome: transduction and transfection. In case of transduction, viral vectors are used to introduce genes into cells, and depending on the selected strain of the virus, a transient or stable duration of protein production can be achieved. In contrast, the transfection of DNA is transmitted by chemical or physical processes such as lipofection, electro- or sonoporation. Relevant risks of gene therapy may be an increasing neo-vascularization in undesired tissue. The risks of malignant transformation and inflammation are the potential drawbacks. Additionally, atherosclerotic plaques can be destabilized by the increased angiogenesis, leading to arterial thrombosis. Clinical trials from pilot studies to Phase II and III studies on angiogenic gene therapy show mainly a mixed picture of positive and negative final results; thus, the role of gene therapy in vascular occlusive disease remains unclear.

The Mechanisms for the Association of Cancer and Esophageal Dysmotility Disorders

BACKGROUND

Achalasia and other esophageal dysmotility disorders mimicking achalasia can be associated with cancer. This study aimed to review the main mechanisms for which cancer may develop in esophageal dysmotility disorder patients.

METHODS

A narrative review was performed.

RESULTS

The mechanism for developing squamous cell carcinoma and adenocarcinoma are discussed. Besides, achalasia-like syndromes related to familial KIT-gene mutation and pseudoachalasia are discussed.

CONCLUSIONS

Knowing the main mechanism for which achalasia can be related to cancer is essential for clinicians to conduct the proper investigation, surveillance, and treatment.

Mechanistic insights of adipocyte metabolism in regulating breast cancer progression

Adipocyte account for the largest component in breast tissue. Dysfunctional adipocyte metabolism, such as metaflammation in metabolically abnormal obese patients, will cause hyperplasia and hypertrophy of its constituent adipocytes. Inflamed adipose tissue is one of the biggest risk factors causing breast cancer. Factors linking adipocyte metabolism to breast cancer include dysfunctional secretion of proinflammatory mediators, proangiogenic factors and estrogens. The accumulation of tumor supporting cells and systemic effects, such as insulin resistance, dyslipidemia and oxidative stress, which are caused by abnormal adipocyte metabolism, further contribute to a more aggressive tumor microenvironment and stimulate breast cancer stem cell to influence the development and progression of breast cancer. Here, in this review, we focus on the adipocyte metabolism in regulating breast cancer progression, and discuss the potential targets which can be used for breast cancer therapy.

Targeting nitric oxide for cancer therapy

A blueprint for the ideal anticancer molecule would include most of the properties of nitric oxide (NO•), but the ability to exploit these characteristics in a therapeutic setting requires a detailed understanding of the biology and biochemistry of the molecule. These properties include the ability of NO• to affect tumour angiogenesis, metastasis, blood flow and immuno surveillance. Furthermore NO• also has the potential to enhance both radio- and chemotherapy. However, all of these strategies are dependent on achieving appropriate levels of NO•, since endogenous levels of NO• appear to have a clear role in tumour progression. This review aims to summarize the role of NO• in cancer with particular emphasis on how the properties of NO• can be exploited for therapy.

Therapeutic angiogenesis in diabetes and hypercholesterolemia: influence of oxidative stress

Despite significant improvements in the medical, percutaneous, and surgical management, numerous patients are first seen with non-revascularizable coronary artery disease (CAD). The growth of new blood vessels to improve myocardial perfusion (i.e., therapeutic angiogenesis) is an attractive treatment option for these patients. However, the successes of angiogenic therapy, observed in preclinical studies, have not been realized in clinical trials. Increasing evidence suggests that this discrepancy between animal and human studies may be due to the nature of the substrate, or the molecular and cellular environment within which the angiogenic agent acts. Antiangiogenic influences, including endothelial dysfunction, hypercholesterolemia, and diabetes, are present in virtually all patients with advanced CAD. Recent studies have better characterized the abnormalities associated with these disease states, providing novel targets for intervention. These substrate-modifying interventions can potentially enhance the response to protein-, gene-, or cell-based angiogenic therapy. In this review, we discuss key aspects of the angiogenic process and the pathophysiologic and molecular mechanisms that contribute to an impaired angiogenic response in the setting of endothelial dysfunction, hypercholesterolemia, and diabetes, with a focus on the role of oxidative stress. Last, we briefly explore substrate modifying agents that have been evaluated in preclinical and clinical studies to improve the angiogenic response.

Isolated limb perfusion with TNF-alpha and melphalan in locally advanced soft tissue sarcomas of the extremities

Limb-sparing surgery has become all the more important in soft tissue sarcoma (STS) of the extremities since we learned that amputation does not improve survival of these patients. In bulky tumours, however, preoperative strategies to reduce tumour size are then required. Isolated limb perfusion (ILP) with tumour necrosis factor (TNF) has been developed as a biochemotherapeutic therapy to act both on the tumour-associated vasculature and on the tumour itself. It has shown to be a very potent treatment modality, as in early reports response rates were around 80%. Limb salvage could then be achieved in a quite similar percentage. Many confirmatory studies have been performed since, with consistent results even in patients with multiple tumours, after extensive radiotherapy or with metastatic disease, all at the cost of very limited toxicity. This chapter gives an overview of the ILP studies performed in patients with soft tissue limb sarcoma, discusses the mechanism of TNF-mediated vasculotoxic effects on tumour vasculature, and places TNF-based ILP in the multimodality treatment of these patients with extensive STS of the extremities.

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.

Thrombospondin 1 and vasoactive agents indirectly alter tumor blood flow

Nitric oxide (NO) plays important physiological roles in the vasculature to regulate angiogenesis, blood flow, and hemostasis. In solid tumors, NO is generally acknowledged to mediate angiogenic responses to several growth factors. This contrasts with conflicting evidence that NO can acutely increase tumor perfusion through local vasodilation or diminish perfusion by preferential relaxation of peripheral vascular beds outside the tumor. Because thrombospondin 1 (TSP1) is an important physiological antagonist of NO in vascular cells, we examined whether, in addition to inhibiting tumor angiogenesis, TSP1 can acutely regulate tumor blood flow. We assessed this activity of TSP1 in the context of perfusion responses to NO as a vasodilator and epinephrine as a vasoconstrictor. Nitric oxide treatment of wild type and TSP1 null mice decreased perfusion of a syngeneic melanoma, whereas epinephrine transiently increased tumor perfusion. Acute vasoactive responses were also independent of the level of tumor-expressed TSP1 in a melanoma xenograft, but recovery of basal perfusion was modulated by TSP1 expression. In contrast, overexpression of truncated TSP1 lacking part of its CD47 binding domain lacked this modulating activity. These data indicate that TSP1 primarily regulates long-term vascular responses in tumors, in part, because the tumor vasculature has a limited capacity to acutely respond to vasoactive agents.

Cytotoxicity of goniothalamin enantiomers in renal cancer cells: involvement of nitric oxide, apoptosis and autophagy

Goniothalamin is a styryllactone synthesized by plants of the genus Goniothalamus. The biological activities of this molecule, particularly its anti-protozoan, anti-fungal, and larvicidal properties, have received considerable attention. In this work, we investigated the action of the natural and synthetic enantiomers (R)-goniothalamin (1) and (S)-goniothalamin (ent-1) on cell viability, nitric oxide synthase (NOS) expression and activity, and the expression of selected proteins involved in apoptosis and autophagy in renal cancer cells. Both compounds were cytotoxic and decreased the mitochondrial function of renal cancer cells. However, the enantiomers differentially affected the expression/activity profiles of some signaling pathway mediators. Ent-1 (4 nM) was more potent than 1 (6.4 microM) in inhibiting constitutive NOS activity (54% and 59% inhibition, respectively), and both enantiomers decreased the protein expression of neuronal and endothelial NOS, as assessed by western blotting. Ent-1 and 1 caused down-regulation of Ras and TNFR1 and inhibition of protein serine/threonine phosphatase 2A (PP2A). Compound 1 markedly down-regulated Bcl2, an anti-apoptotic protein, and also induced PARP cleavage. Despite inducing an expressive down-regulation of Bax, ent-1 was also able to induce PARP cleavage. These results suggest that these compounds caused apoptosis in renal cancer cells. Interestingly, ent-1 enhanced the expression of LC3, a typical marker of autophagy. NFkappaB was down-regulated in 1-treated cells. Overall, these results indicate that the anti-proliferative activity of the two enantiomers on renal cancer cells involved distinct signaling pathways, apoptosis and autophagy as dominant responses towards 1 and ent-1, respectively.

iNOS-dependent DNA damage in patients with malignant fibrous histiocytoma in relation to prognosis

Malignant fibrous histiocytoma (MFH) is one of the most common soft tissue sarcomas. MFH has been proposed to be a lesion accompanied with inflammatory responses. During chronic inflammation, reactive nitrogen and oxygen species generated from inflammatory cells are considered to participate in carcinogenesis by causing DNA damage. 8-nitroguanine is a mutagenic nitrative DNA lesion formed during chronic inflammation. We examined whether nitrative DNA damage is related to the prognosis of MFH patients. We performed immunohistochemical analyses to examine the distribution of DNA damage and the expression of inflammation-related molecules including inducible nitric oxide synthase (iNOS), nuclear factor-kappaB (NF-kappaB), and cyclooxygenase-2 (COX-2) in clinical specimens from 25 patients with MFH. We also analyzed the correlation of DNA damage or the expression of these genes with the prognosis of MFH patients. Immunohistochemical staining revealed that the formation of 8-nitroguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), an oxidative DNA lesion, occurred to a much greater extent in MFH tissue specimens from deceased patients than in live patients. iNOS, NF-kappaB and COX-2 were colocalized with 8-nitroguanine in MFH tissues. It is noteworthy that the statistical analysis using the Kaplan-Meier method demonstrated strong 8-nitroguanine staining to be associated with a poor prognosis. In conclusion, 8-nitroguanine appears to participate in not only the initiation and promotion of MFH, but also in the progression of MFH, and could therefore be used as a promising biomarker to evaluate the prognosis of cancer patients.

Nitric oxide, a double edged sword in cancer biology: Searching for therapeutic opportunities

Nitric oxide (NO) is a pleiotropic molecule critical to a number of physiological and pathological processes. The last decade has witnessed major advances in dissecting NO biology and its role in cancer pathogenesis. However, the complexity of the interactions between different levels of NO and several aspects of tumor development/progression has led to apparently conflicting findings. Furthermore, both anti-NO and NO-based anticancer strategies appear effective in several preclinical models. This paradoxical dichotomy is leaving investigators with a double challenge: to determine the net impact of NO on cancer behavior and to define the therapeutic role of NO-centered anticancer strategies. Only a comprehensive and dynamic view of the cascade of molecular and cellular events underlying tumor biology and affected by NO will allow investigators to exploit the potential antitumor properties of drugs interfering with NO metabolism. Available data suggest that NO should be considered neither a universal target nor a magic bullet, but rather a signal transducer to be modulated according to the molecular makeup of each individual cancer and the interplay with conventional antineoplastic agents.

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.

Tumour angiogenesis: a novel therapeutic target in patients with malignant disease

Angiogenesis refers to the formation of new blood vessels from an existing vasculature and is recognised as a necessary requirement for most tumours to grow beyond 1-2 mm in diameter. Factors established as playing a role in angiogenesis may be divided into two principal groups: (a) those that stimulate endothelial cell proliferation and/or elongation, migration and vascular morphogenesis including vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), platelet derived endothelial cell growth factor (PD-ECGF) and the tie and tek receptors, and (b) proteases and their receptors involved in the breakdown of basement membranes and the extracellular matrix (ECM) including the matrix metalloproteinases (MMPs), cathepsins and those involved in the plasmin cascade. Angiogenesis has been identified as a potential target for development of anticancer agents. The discovery of a range of naturally-occurring factors which negatively regulate angiogenesis, including the thrombospondins, angiostatin and endostatin, and the tissue inhibitors of MMPs (TIMPs), has given added impetus to this approach. Synthetic anti-angiogenic compounds have been developed, including TNP-470, carboxyamidotriazole, VEGF-tyrosine kinase inhibitors and MMP inhibitors (MMPI) which, like the naturally-occurring anti-angiogenic factors, inhibit angiogenesis in vitro and in vivo, and tumour development, growth and metastasis in vivo. Anti-angiogenic agents also enhance the antitumour activity of many conventional cytotoxic chemotherapeutic agents. Such combinations may have a particular role as adjuvant therapies following surgical resection of primary tumours. Unlike tumour cells, tumour associated endothelial cells do not develop resistance to anti-angiogenic agents. Furthermore, anti-angiogenic agents are generally cytostatic rather than cytotoxic. As such, these agents are, in general, likely to be administered over long periods of time. Therefore, as well as having proven antitumour efficacy, an anti-angiogenic compound will need to be well-tolerated if it is to become established in the clinical management of patients with malignant disease.

Induction of endothelial nitric oxide synthase expression by melanoma sensitizes endothelial cells to tumor necrosis factor-driven cytotoxicity

PURPOSE

The cascade of molecular events leading to tumor necrosis factor (TNF)-mediated tumor regression is still incompletely elucidated. We investigated the role of endothelial nitric oxide synthase in determining the tumor-selective activity of TNF.

EXPERIMENTAL DESIGN

Using quantitative real-time PCR, endothelial nitric oxide synthase gene levels were measured in melanoma metastases of the skin and normal skin biopsies obtained from 12 patients before undergoing TNF-based therapy. In vitro, the ability of melanoma cells supernatant to affect endothelial nitric oxide synthase transcription by endothelial cells and the influence of nitric oxide synthase inhibition on TNF cytotoxicity toward endothelial cells was evaluated.

RESULTS

Endothelial nitric oxide synthase transcript abundance resulted significantly greater in tumor samples rather than in normal skin samples and in patients showing complete response to TNF-based treatment rather than in those showing partial/minimal response. In vitro, melanoma cells' supernatant induced endothelial nitric oxide synthase gene expression by endothelial cells. Nitric oxide synthase inhibition slowed endothelial cells proliferation and, if induced before TNF administration, decreased the cytokine-mediated cytotoxicity on endothelial cells.

CONCLUSIONS

Taken together, these findings support the hypothesis that high expression of endothelial nitric oxide synthase in the tumor microenvironment might increase or be a marker for endothelial cells sensitivity to TNF. These observations may have important prognostic and/or therapeutic implications in the clinical setting.

Arginine and cancer

Arginine is a dibasic, cationic, semiessential amino acid with numerous roles in cellular metabolism. It serves as an intermediate in the urea cycle and as a precursor for protein, polyamine, creatine and nitric oxide (NO) biosynthesis. Arginine is conditionally essential since it becomes necessary under periods of growth and after recovery after injury. Arginine also promotes wound healing and functions as a secretagogue stimulating the release of growth hormone, insulin-like growth factor 1, insulin, and prolactin. Furthermore, arginine has several immunomodulatory effects such as stimulating T- and natural killer cell activity and influencing pro-inflammatory cytokine levels. The discover that l-arginine is the sole precursor for the multifunctional messenger molecule nitric oxide (NO) led to investigation into the role of arginine in numerous physiologic and pathophysiologic phenomena including cancer. Although NO was first identified in endothelial cells, it is now recognized to be generated by a variety of cell types, including several tumor cell lines and solid human tumors. Unfortunately, the precise role of NO in cancer is poorly understood but it may influence tumor initiation, promotion, and progression, tumor-cell adhesion, apoptosis angiogenesis, differentiation, chemosensitivity, radiosensitivity, and tumor-induced immunosuppression. The biological effects of NO are complex and dependent upon numerous regulatory factors. Further research is necessary to enhance our understanding of the complex mechanisms that regulate NO's role in tumor biology. A better understanding of the role of arginine-derived NO in cancer may lead to novel antineoplastic and chemopreventative strategies.

Report from the Society for Biological Therapy and Vascular Biology Faculty of the NCI Workshop on Angiogenesis Monitoring

The field of tumor angiogenesis has seen explosive growth over the last 5 years. Preclinical as well as early clinical evaluation of novel compounds is progressing at a rapid pace. To gain a perspective on the field and to take stock of advances in the understanding of molecular mechanisms underlying the process of tumor angiogenesis as well as ways of monitoring the activity of agents, the Society for Biologic Therapy and the National Cancer Institute's Vascular Biology Faculty convened a Workshop on Angiogenesis Monitoring in November 2002. The Workshop was composed of invited speakers and participants from academia, industry, and government. It was divided into 3 sessions, each chaired by leaders in the field. The first focused on advances in the understanding of the cellular and molecular mechanisms of angiogenesis in tumors. The second examined preclinical assay systems that are useful in vascular biology. The third addressed the translation to the clinic and monitoring of antiangiogenic activity of agents in patients and novel trial designs. What follows is a summary of the discussions and findings of each session.

Role of nitric oxide in tumor angiogenesis

Nitric oxide (NO) is an important signalling molecule that acts in many tissues to regulate different physiological and pathological processes. We have contributed to demonstrate that NO stimulates angiogenesis and mediates the effect of different angiogenic molecules. In human tumors NOS expression and activity correlate with tumor growth and aggressiveness, through angiogenesis stimulation and regulation of angiogenic factor expression. Drugs affecting the NOS pathway appear promising antitumor strategies by reducing edema, inhibiting angiogenesis and facilitating the delivery of chemotherapeutical agents.

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.

A nitric oxide synthase inhibitor, N(G)-nitro-l-arginine-methyl-ester, exerts potent antiangiogenic effects on plasmacytoma in a newly established multiple myeloma severe combined immunodeficient mouse model

Angiogenesis is one of critical factors in sustaining the growth, invasion and metastasis of certain solid tumours and haematological malignancies such as multiple myeloma (MM). In the present study, we examined the anticancer potential of an inhibitor of nitric oxide synthase (NOS), NG-nitro-l-arginine methyl ester (L-NAME), in a novel severe combined immunodeficient mouse model (KHM mouse) that harbours the highly sanguineous plasmacytoma cell line KHM-4, derived from a patient with highly chemoresistant MM. KHM mice were intraperitoneally administered with either L-NAME, doxorubicin, melphalan, or paclitaxel. A significant reduction in tumour sizes was noted in L-NAME-administered KHM mice while no significant reduction was observed in melphalan- or doxorubicin-administered mice. A profound decrease in angiogenesis was observed in tumour tissues from L-NAME- and paclitaxel-administered KHM mice. A marked decrease in human vascular endothelial cell growth factor (VEGF) levels was identified in tumour tissues from L-NAME-administered KHM mice, strongly suggesting that L-NAME suppressed VEGF production by tumour cells through its inhibition of NOS in tumour cells, resulting in reduced neovasculization in mice leading to the regression of tumour sizes. The present data represent the first observations that certain NOS inhibitors potentially serve as experimental agents for the treatment of chemoresistant MM and plasmacytoma.

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.

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.