Phase I study of recombinant human tumor necrosis factor

Clostridium Bacteria: Harnessing Tumour Necrosis for Targeted Gene Delivery

Necrosis is a common feature of solid tumours that offers a unique opportunity for targeted cancer therapy as it is absent from normal healthy tissues. Tumour necrosis provides an ideal environment for germination of the anaerobic bacterium Clostridium from endospores, resulting in tumour-specific colonisation. Two main species, Clostridium novyi-NT and Clostridium sporogenes, are at the forefront of this therapy, showing promise in preclinical models. However, anti-tumour activity is modest when used as a single agent, encouraging development of Clostridium as a tumour-selective gene delivery system. Various methods, such as allele-coupled exchange and CRISPR-cas9 technology, can facilitate the genetic modification of Clostridium, allowing chromosomal integration of transgenes to ensure long-term stability of expression. Strains of Clostridium can be engineered to express prodrug-activating enzymes, resulting in the generation of active drug selectively in the tumour microenvironment (a concept termed Clostridium-directed enzyme prodrug therapy). More recently, Clostridium strains have been investigated in the context of cancer immunotherapy, either in combination with immune checkpoint inhibitors or with engineered strains expressing immunomodulatory molecules such as IL-2 and TNF-α. Localised expression of these molecules using tumour-targeting Clostridium strains has the potential to improve delivery and reduce systemic toxicity. In summary, Clostridium species represent a promising platform for cancer therapy, with potential for localised gene delivery and immunomodulation selectively within the tumour microenvironment. The ongoing clinical progress being made with C. novyi-NT, in addition to developments in genetic modification techniques and non-invasive imaging capabilities, are expected to further progress Clostridium as an option for cancer treatment.

Dynamic polarization of tumor-associated macrophages and their interaction with intratumoral T cells in an inflamed tumor microenvironment: from mechanistic insights to therapeutic opportunities

Immunotherapy has brought a paradigm shift in the treatment of tumors in recent decades. However, a significant proportion of patients remain unresponsive, largely due to the immunosuppressive tumor microenvironment (TME). Tumor-associated macrophages (TAMs) play crucial roles in shaping the TME by exhibiting dual identities as both mediators and responders of inflammation. TAMs closely interact with intratumoral T cells, regulating their infiltration, activation, expansion, effector function, and exhaustion through multiple secretory and surface factors. Nevertheless, the heterogeneous and plastic nature of TAMs renders the targeting of any of these factors alone inadequate and poses significant challenges for mechanistic studies and clinical translation of corresponding therapies. In this review, we present a comprehensive summary of the mechanisms by which TAMs dynamically polarize to influence intratumoral T cells, with a focus on their interaction with other TME cells and metabolic competition. For each mechanism, we also discuss relevant therapeutic opportunities, including non-specific and targeted approaches in combination with checkpoint inhibitors and cellular therapies. Our ultimate goal is to develop macrophage-centered therapies that can fine-tune tumor inflammation and empower immunotherapy.

Sunitinib Combined with Th1 Cytokines Potentiates Apoptosis in Human Breast Cancer Cells and Suppresses Tumor Growth in a Murine Model of HER-2pos Breast Cancer

Although immune-based therapies have made remarkable inroads in cancer treatment, they usually must be combined with standard treatment modalities, including cytotoxic drugs, to achieve maximal clinical benefits. As immunotherapies are further advanced and refined, considerable efforts will be required to identify combination therapies that will maximize clinical responses while simultaneously decreasing the unpleasant and sometimes life-threatening side effects of standard therapy. Over the last two decades, evidence has emerged that Th1 cytokines can play a central role in protective antitumor immunity and that combinations of Th1 cytokines can induce senescence and apoptosis in cancer cells. To explore the possibility of combining targeted drugs with Th1-polarizing vaccines, we undertook a study to examine the impact of combining Th1 cytokines with the relatively broad-spectrum receptor tyrosine kinase antagonist, sunitinib. We found that when a panel of five phenotypically diverse human breast cancer cell lines was subjected to treatment with sunitinib plus recombinant Th1 cytokines IFN-γ and TNF-α, synergistic effects were observed across a number of parameters including different aspects of apoptotic cell death. Interestingly, sunitinib was found to have a profoundly suppressive effect of T cell's capacity to secrete IFN-γ, indicating that in vivo use of this drug may hinder robust Th1 responses. Nonetheless, this suppression was circumvented in a mouse model of HER-2^pos breast disease by supplying recombinant interferon-gamma to achieve a combination therapy significantly more potent than either agent.

Targeting apoptosis in cancer therapy

For over three decades, a mainstay and goal of clinical oncology has been the development of therapies promoting the effective elimination of cancer cells by apoptosis. This programmed cell death process is mediated by several signalling pathways (referred to as intrinsic and extrinsic) triggered by multiple factors, including cellular stress, DNA damage and immune surveillance. The interaction of apoptosis pathways with other signalling mechanisms can also affect cell death. The clinical translation of effective pro-apoptotic agents involves drug discovery studies (addressing the bioavailability, stability, tumour penetration, toxicity profile in non-malignant tissues, drug interactions and off-target effects) as well as an understanding of tumour biology (including heterogeneity and evolution of resistant clones). While tumour cell death can result in response to therapy, the selection, growth and dissemination of resistant cells can ultimately be fatal. In this Review, we present the main apoptosis pathways and other signalling pathways that interact with them, and discuss actionable molecular targets, therapeutic agents in clinical translation and known mechanisms of resistance to these agents.

The dual role of tumor necrosis factor-alpha (TNF-α) in breast cancer: molecular insights and therapeutic approaches

BACKGROUND

Breast cancer is the most prevalent cancer among women worldwide and the fifth cause of death among all cancer patients. Breast cancer development is driven by genetic and epigenetic alterations, with the tumor microenvironment (TME) playing an essential role in disease progression and evolution through mechanisms like inflammation promotion. TNF-α is one of the essential pro-inflammatory cytokines found in the TME of breast cancer patients, being secreted both by stromal cells, mainly by tumor-associated macrophages, and by the cancer cells themselves. In this review, we explore the biological and clinical impact of TNF-α in all stages of breast cancer development. First of all, we explore the correlation between TNF-α expression levels at the tumor site or in plasma/serum of breast cancer patients and their respective clinical status and outcome. Secondly, we emphasize the role of TNF-α signaling in both estrogen-positive and -negative breast cancer cells. Thirdly, we underline TNF-α involvement in epithelial-to-mesenchymal transition (EMT) and metastasis of breast cancer cells, and we point out the contribution of TNF-α to the development of acquired drug resistance.

CONCLUSIONS

Collectively, these data reveal a pro-tumorigenic role of TNF-α during breast cancer progression and metastasis. We systemize the knowledge regarding TNF-α-related therapies in breast cancer, and we explain how TNF-α may act as both a target and a drug in different breast cancer therapeutic approaches. By corroborating the known molecular effects of TNF-α signaling in breast cancer cells with the results from several preclinical and clinical trials, including TNF-α-related clinical observations, we conclude that the potential of TNF-α in breast cancer therapy promises to be of great interest.

Oroxylin A, a natural compound, mitigates the negative effects of TNFα-treated acute myelogenous leukemia cells

Tumor necrosis factor alpha (TNFα) is a complicated cytokine which is involved in proliferation and differentiation of acute myelogenous leukemia (AML) cells through a poorly understood mechanism. Mechanistic studies indicate that TNFα induced binding of PI3K subunit p85α to N-terminal truncated nuclear receptor RXRα (tRXRα) proteins, and activated AKT. The activated PI3K/AKT pathway negatively regulated differentiation of AML cells through the upregulation of c-Myc. In addition, TNFα also induced activation of nuclear factor κB (NF-κB), a nuclear transcription factor which was shown to promote cell proliferation. The present study demonstrates that oroxylin A, a natural compound isolated from Scutellariae radix, sensitizes leukemia cells to TNFα and markedly enhances TNFα-induced growth inhibition and differentiation of AML cell including human leukemia cell lines and primary AML cells. Activation of PI3K/AKT pathway could be inhibited by oroxylin A through inhibiting expression of tRXRα in NB4 and HL-60-resistant cells. Furthermore, we found that oroxylin A inhibited the activation of NF-κB and the DNA binding activity by TNFα proved by EMSA in these two AML cell lines. Moreover, in vivo studies showed that treatment with oroxylin A in combination with TNFα decreased AML cell population and prolonged survival in NOD/SCID mice with xenografts of primary AML cells. Overall, our results indicate that oroxylin A is able to inhibit the negative effects of TNFα for AML therapy, suggesting that combination of oroxylin A and TNFα have the potential to delay growth or eliminate the abnormal leukemic cells, thus representing a promising strategy for AML treatment.

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.

Anti-cancer therapy with TNFα and IFNγ: A comprehensive review

Tumour necrosis factor alpha (TNFα) and interferon gamma (IFNγ) were originally found to be produced by inflammatory cells and play important roles in the immune system and surveillance of tumour growth. By activating distinct signalling pathways of nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), and JAK/STAT, TNFα and IFNγ were reported to effectively trigger cell death and perform powerful anti-cancer effects. In this review, we will discuss the new advancements of TNFα and IFNγ in anti-cancer therapy.

Therapeutic applications of TRAIL receptor agonists in cancer and beyond

TRAIL/Apo-2L is a member of the TNF superfamily first described as an apoptosis-inducing cytokine in 1995. Similar to TNF and Fas ligand, TRAIL induces apoptosis in caspase-dependent manner following TRAIL death receptor trimerization. Because tumor cells were shown to be particularly sensitive to this cytokine while normal cells/tissues proved to be resistant along with being able to synthesize and release TRAIL, it was rapidly appreciated that TRAIL likely served as one of our major physiologic weapons against cancer. In line with this, a number of research laboratories and pharmaceutical companies have attempted to exploit the ability of TRAIL to kill cancer cells by developing recombinant forms of TRAIL or TRAIL receptor agonists (e.g., receptor-specific mAb) for therapeutic purposes. In this review article we will describe the biochemical pathways used by TRAIL to induce different cell death programs. We will also summarize the clinical trials related to this pathway and discuss possible novel uses of TRAIL-related therapies. In recent years, the physiological importance of TRAIL has expanded beyond being a tumoricidal molecule to one critical for a number of clinical settings - ranging from infectious disease and autoimmunity to cardiovascular anomalies. We will also highlight some of these conditions where modulation of the TRAIL/TRAIL receptor system may be targeted in the future.

Type I interferons promote severe disease in a mouse model of lethal ehrlichiosis

Human monocytic ehrlichiosis (HME) is caused by a tick-borne obligate intracellular pathogen of the order Rickettsiales. HME disease can range from mild to a fatal, toxic shock-like syndrome, yet the mechanisms regulating pathogenesis are not well understood. We define a central role for type I interferons (alpha interferon [IFN-α] and IFN-β) in severe disease in a mouse model of fatal ehrlichiosis caused by Ixodes ovatus Ehrlichia (IOE). IFN-α and IFN-β were induced by IOE infection but not in response to a less virulent strain, Ehrlichia muris. The major sources of type I IFNs during IOE infection were plasmacytoid dendritic cells and monocytes. Mice lacking the receptor for type I IFNs (Ifnar deficient) or neutralization of IFN-α and IFN-β resulted in a reduced bacterial burden. Ifnar-deficient mice exhibited significantly increased survival after IOE infection, relative to that of wild-type (WT) mice, that correlated with increased type II IFN (IFN-γ) production. Pathogen-specific antibody responses were also elevated in Ifnar-deficient mice, and this required IFN-γ. Remarkably, increased IFN-γ and IgM were not essential for protection in the absence of type I IFN signaling. The direct effect of type I IFNs on hematopoietic and nonhematopoietic cells was evaluated in bone marrow chimeric mice. We observed that chimeric mice containing Ifnar-deficient hematopoietic cells succumbed to infection early, whereas Ifnar-deficient mice containing WT hematopoietic cells exhibited increased survival, despite having a higher bacterial burden. These data demonstrate that IFN-α receptor signaling in nonhematopoietic cells is important for pathogenesis. Thus, type I IFNs are induced during a rickettsial infection in vivo and promote severe disease.

TNF-dependent signaling pathways in liver cancer: promising targets for therapeutic strategies?

Liver cancer represents a growing health burden worldwide, and treatment options are still limited. Hepatocellular carcinoma (HCC), the most frequent primary hepatic malignancy, arises in most instances in chronically inflamed and fibrotic livers. However, current systemic molecular therapies against HCC are mainly focusing on tyrosine kinases involved in angiogenic and oncogenic signaling pathways, whereas the knowledge on the unique association between inflammation and carcinogenesis in the liver has not yet translated into preventive or therapeutic concepts against HCC. Tumor necrosis factor (TNF) is a cytokine derived from monocytes and various other immunological and parenchymal cells. Upon binding to its receptors, TNF activates different signaling cascades including the pro-apoptotic caspase cascade as well as inflammatory and stress-related pathways such as the NF-ĸB, p38MAPK, and Jun-(N)-terminal kinase (JNK) pathways. The role of TNF in cancer is controversial, since it was attributed both pro- and anti-carcinogenic functions. Its potential function in hepatocarcinogenesis has lately been investigated using genetically modified mouse models. These studies have highlighted that the various TNF-dependent signaling pathways withhold distinct functions in hepatocarcinogenesis, which are in part controversial and strongly depend on the experimental model system. Nevertheless, careful interpretation of findings in mouse models and critical consideration of their limitations might result in a new understanding of this complex pathway in hepatocarcinogenesis and thus might help identify the most promising targets in the TNF pathway and the appropriate clinical settings for future chemo-preventive or therapeutic strategies against HCC.

Systemic use of tumor necrosis factor alpha as an anticancer agent

Tumor necrosis factor-α (TNF-α) has been discussed as a potential anticancer agent for many years, however initial enthusiasm about its clinical use as a systemic agent was curbed due to significant toxicities and lack of efficacy. Combination of TNF-α with chemotherapy in the setting of hyperthermic isolated limb perfusion (ILP), has provided new insights into a potential therapeutic role of this agent. The therapeutic benefit from TNF-α in ILP is thought to be not only due to its direct anti-proliferative effect, but also due to its ability to increase penetration of the chemotherapeutic agents into the tumor tissue. New concepts for the use of TNF-α as a facilitator rather than as a direct actor are currently being explored with the goal to exploit the ability of this agent to increase drug delivery and to simultaneously reduce systemic toxicity.

This review article provides a comprehensive overview on the published previous experience with systemic TNF-α. Data from 18 phase I and 10 phase II single agent as well as 18 combination therapy studies illustrate previously used treatment and dose schedules, response data as well as the most prominently observed adverse effects. Also discussed, based on recent preclinical data, is a potential future role of systemic TNF-α in combination with liposomal chemotherapy to facilitate increased drug uptake into tumors.

State of the art in PEGylation: the great versatility achieved after forty years of research

In the recent years, protein PEGylation has become an established and highly refined technology by moving forward from initial simple random coupling approaches based on conjugation at the level of lysine ε-amino group. Nevertheless, amino PEGylation is still yielding important conjugates, currently in clinical practice, where the degree of homogeneity was improved by optimizing the reaction conditions and implementing the purification processes. However, the current research is mainly focused on methods of site-selective PEGylation that allow the obtainment of a single isomer, thus highly increasing the degree of homogeneity and the preservation of bioactivity. Protein N-terminus and free cysteines were the first sites exploited for selective PEGylation but currently further positions can be addressed thanks to approaches like bridging PEGylation (disulphide bridges), enzymatic PEGylation (glutamines and C-terminus) and glycoPEGylation (sites of O- and N-glycosylation or the glycans of a glycoprotein). Furthermore, by combining the tools of genetic engineering with specific PEGylation approaches, the polymer can be basically coupled at any position on the protein surface, owing to the substitution of a properly chosen amino acid in the sequence with a natural or unnatural amino acid bearing an orthogonal reactive group. On the other hand, PEGylation has not achieved the same success in the delivery of small drugs, despite the large interest and several studies in this field. Targeted conjugates and PEGs for combination therapy might represent the promising answers for the so far unmet needs of PEG as carrier of small drugs. This review presents a thorough panorama of recent advances in the field of PEGylation.

Development of a novel DDS for site-specific PEGylated proteins

Because of the shifted focus in life science research from genome analyses to genetic and protein function analyses, we now know functions of numerous proteins. These analyses, including those of newly identified proteins, are expected to contribute to the identification of proteins of therapeutic value in various diseases. Consequently, pharmacoproteomic-based drug discovery and development of protein therapies attracted a great deal of attention in recent years. Clinical applications of most of these proteins are, however, limited because of their unexpectedly low therapeutic effects, resulting from the proteolytic degradation in vivo followed by rapid removal from the circulatory system. Therefore, frequent administration of excessively high dose of a protein is required to observe its therapeutic effect in vivo. This often results in impaired homeostasis in vivo and leads to severe adverse effects. To overcome these problems, we have devised a method for chemical modification of proteins with polyethylene glycol (PEGylation) and other water-soluble polymers. In addition, we have established a method for creating functional mutant proteins (muteins) with desired properties, and developed a site-specific polymer-conjugation method to further improve their therapeutic potency. In this review, we are introducing our original protein-drug innovation system mentioned above.

The value of failure: the discovery of TNF and its natural inhibitor erythropoietin

The hurtful feelings associated with failing can be devastating especially if the failure occurs after the investment of a considerable effort. The reflection of a lifetime of work in translational medicine has revealed that the study of failures can give birth to new insights that can be explored with important consequences. This article discusses the analysis of two failures that have led to remarkable discoveries. The first led to the discovery of TNF as an important mediator of inflammation that can, if unchecked, cause severe damage in mammals. The second is the identification of erythropoietin as the natural inhibitor of the production and biological activity of TNF. I hope that this paper will help give students the courage to persist in looking for the insights that are the by-products of failure, and to understand the long time lines in the path of discoveries.

Phase I and pharmacokinetic studies of CYT-6091, a novel PEGylated colloidal gold-rhTNF nanomedicine

PURPOSE

A novel nanomedicine, CYT-6091, constructed by simultaneously binding recombinant human tumor necrosis factor alpha (rhTNF) and thiolyated polyethylene glycol to the surface of 27-nm colloidal gold particles, was tested in a phase I dose escalation clinical trial in advanced stage cancer patients.

EXPERIMENTAL DESIGN

CYT-6091, whose dosing was based on the amount of rhTNF in the nanomedicine, was injected intravenously, and 1 cycle of treatment consisted of 2 treatments administered 14 days apart.

RESULTS

Doses from 50 μg/m(2) to 600 μg/m(2) were well tolerated, and no maximum tolerated dose (MTD) was reached, as the highest dose exceeded the target dosage of 1-mg rhTNF per treatment, exceeding the previous MTD for native rhTNF by 3-fold. The first 2 patients on the study, each receiving 50 μg/m(2), did not receive any prophylactic antipyretics or H2 blockade. A predicted, yet controllable fever occurred in these patients, so all subsequently treated patients received prophylactic antipyretics and H2 blockers. However, even at the highest dose rhTNF's dose-limiting toxic effect of hypotension was not seen. Using electron microscopy to visualize nanoparticles of gold in patient biopsies of tumor and healthy tissue showed that patient biopsies taken 24 hours after treatment had nanoparticles of gold in tumor tissue.

CONCLUSIONS

These data indicate that rhTNF formulated as CYT-6091 may be administered systemically at doses of rhTNF that were previously shown to be toxic and that CYT-6091 may target to tumors. Future clinical studies will focus on combining CYT-6091 with approved chemotherapies for the systemic treatment of nonresectable cancers.

Phase II Study of Asparagine-Glycine-Arginine–Human Tumor Necrosis Factor α, a Selective Vascular Targeting Agent, in Previously Treated Patients With Malignant Pleural Mesothelioma

Purpose

NGR-hTNF consists of human tumor necrosis factor α (hTNF-α) fused to the tumor-homing peptide asparagine-glycine-arginine (NGR) able to selectively bind an aminopeptidase N isoform overexpressed on tumor blood vessels. Hypervascularity is a prominent and poor-prognosis feature of malignant pleural mesothelioma (MPM). Currently, there are no standard options for patients with MPM who are failing a front-line pemetrexed-based regimen. We explored safety and efficacy of NGR-hTNF in this setting.

Patients and Methods

Eligible patients had radiologically documented tumor progression and performance status ≤ 2. Primary study aim was progression-free survival (PFS). NGR-hTNF 0.8 μg/m2 was given intravenously every 3 weeks. A subsequent cohort of patients received 0.8 μg/m2 on a weekly basis.

Results

In the triweekly cohort (n = 43), only one grade 3 drug-related toxicity was noted, and the most common grades 1 to 2 were short-lived chills (71%). The median PFS was 2.8 months (95% CI, 2.3 to 3.3 months). Nineteen patients (44%) had disease control (one had partial response, and 18 had stable diseases) and experienced a median progression-free time of 4.4 months. In the weekly cohort (n = 14), there was no higher toxicity, and median PFS was 3.0 months (95% CI, 1.9 to 4.1 months). Seven patients (50%) had disease control (all stable diseases) and had a median progression-free interval of 9.1 months. In the overall study population (N = 57), median PFS was 2.8 months. Median progression-free time was 4.7 months in twenty-six patients (46%) who achieved disease control. Median survival was 12.1 months.

Conclusion

The tolerability and disease control of NGR-hTNF 0.8 μg/m2 weekly warrant additional evaluation in patients with advanced MPM.

Defining the optimal biological dose of NGR-hTNF, a selective vascular targeting agent, in advanced solid tumours

BACKGROUND

NGR-hTNF consists of human tumour necrosis factor-alpha (hTNF-alpha) fused to the tumour-homing peptide NGR, a ligand of an aminopeptidase N/CD13 isoform, which is overexpressed on endothelial cells of newly formed tumour blood vessels. NGR-TNF showed a biphasic dose-response curve in preclinical models. This study exploring the low-dose range aimed to define safety and optimal biological dose of NGR-hTNF.

PATIENTS AND METHODS

Pharmacokinetics, plasma biomarkers and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) were evaluated at baseline and after each cycle in 16 patients enrolled at four doubling-dose levels (0.2-0.4-0.8-1.6 microg/m(2)). NGR-hTNF was given intravenously as 1-h infusion every 3 weeks (q3w). Tumour response was assessed q6w.

RESULTS

Eighty-three cycles (median, 2; range, 1-29) were administered. Most frequent treatment-related toxicity was grade 1-2 chills (69%), occurring during the first infusions. Only one patient treated at 1.6 microg/m(2) had a grade 3 drug-related toxicity (chills and dyspnoea). Both C(max) and AUC increased proportionally with dose. No shedding of soluble TNF-alpha receptors was observed up to 0.8 microg/m(2). Seventy-five percent of DCE-MRI assessed patients showed a decrease over time of K(trans), which was more pronounced at 0.8 microg/m(2). Seven patients (44%) had stable disease for a median time of 5.9 months, including a colon cancer patient who experienced an 18-month progression-free time.

CONCLUSION

Based on tolerability, soluble TNF-receptors kinetics, anti-vascular effect and disease control, NGR-hTNF 0.8 microg/m(2) will be further developed either as single-agent or with standard chemotherapy.

Phase I clinical and magnetic resonance imaging study of the vascular agent NGR-hTNF in patients with advanced cancers (European Organization for Research and Treatment of Cancer Study 16041)

PURPOSE

This phase I trial investigating the vascular targeting agent NGR-hTNF aimed to determine the (a) dose-limiting toxicities, (b) maximum tolerated dose (MTD), (c) pharmacokinetics and pharmacodynamics, (d) vascular response by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), and (e) preliminary clinical activity in solid tumors.

EXPERIMENTAL DESIGN

NGR-hTNF was administered once every 3 weeks by a 20- to 60-minute i.v. infusion to cohorts of three to six patients with solid tumors in escalating doses. Pharmacokinetic and pharmacodynamic analyses in blood were done during the first four cycles. DCE-MRI was done in cycle 1 at baseline and 2 hours after the start of the infusion.

RESULTS

Sixty-nine patients received a total of 201 cycles of NGR-hTNF (0.2-60 microg/m(2)). Rigors and fever were the most frequently observed toxicities. Four dose-limiting toxicities were observed (at doses of 1.3, 8.1, and 60 microg/m(2)), of which three were infusion related. The MTD was 45 microg/m(2). The mean apparent terminal half-life ranged from 0.963 to 2.08 hours. DCE-MRI results of tumors showed a vascular response to NGR-hTNF. No objective responses were observed, but 27 patients showed stable disease with a median duration of 12 weeks.

CONCLUSIONS

NGR-hTNF was well tolerated. The MTD was 45 microg/m(2) administered in 1 hour once every 3 weeks. DCE-MRI results showed the antivascular effect of NGR-hTNF. These findings call for further research for defining the optimal biological dose and clinical activity of NGR-hTNF as a single agent or in combination with cytotoxic drugs.

Development of human tumor necrosis factor-alpha muteins with improved therapeutic potential

Tumor necrosis factor-alpha (TNF-alpha) exhibits cytotoxicity towards various tumor cells in vitro and induces apoptotic necrosis in transplanted tumors in vivo. It also shows severe toxicity when used systemically for the treatment of cancer patients, hampering the development of TNF-alpha as a potential anticancer drug. In order to understand the structure-function relation of TNF-alpha with respect to receptor binding, we selected four regions on the bottom of the TNF-alpha trimer that are in close contact with the receptor and carried out mutagenesis studies and computational modeling. From the study, various TNF-alpha muteins with a high therapeutic index were identified. These results will provide a structural basis for the design of highly potent TNF-alpha for therapeutic purposes. By conjugating TNF-alpha muteins with a high therapeutic index to a fusion partner, which targets a marker of angiogenesis, it could be possible to develop TNF-alpha based anticancer drugs.

Tumour necrosis factor and cancer

Tumour necrosis factor (TNF) is a major inflammatory cytokine that was first identified for its ability to induce rapid haemorrhagic necrosis of experimental cancers. When efforts to harness this anti-tumour activity in cancer treatments were underway, a paradoxical tumour-promoting role of TNF became apparent. Now that links between inflammation and cancer are appreciated, is TNF a target or a therapeutic in malignant disease -- or both?

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.

Role of amino acid residue 90 in bioactivity and receptor binding capacity of tumor necrosis factor mutants

We have previously produced two bioactive lysine-deficient mutants of TNF-alpha (mutTNF-K90R,-K90P) and found that these mutants have bioactivity superior to wild-type TNF (wtTNF). Because these mutants contained same amino acid except for amino acid 90, it is unclear which amino acid residue is optimal for showing bioactivity. We speculated that this amino acid position was exchangeable, and this amino acid substitution enabled the creation of lysine-deficient mutants with enhanced bioactivity. Therefore, we produced mutTNF-K90R variants (mutTNF-R90X), in which R90 was replaced with other amino acids, to assay their bioactivities and investigated the importance of amino acid position 90. As a result, mutTNF-R90X that replaced R90 with lysine, arginine and proline were bioactive, while other mutants were not bioactive. Moreover, these three mutants showed bioactivity as good as or better than wtTNF. R90 replaced with lysine or arginine had especially superior binding affinities. These results suggest that the amino acid position 90 in TNF-alpha is important for TNF-alpha bioactivity and could be altered to improve its bioactivity to generate a "super-agonist".

Intracellular survival pathways in the liver

Recent studies have drawn attention to cytokines as important modulators of hepatocyte cell death during acute and chronic liver disease. Through interaction with cell surface receptors, they activate specific intracellular pathways that influence cell fate in different manners. For example, tumor necrosis factor not only induces proapoptotic signals via the caspase cascade but also activates intracellular survival pathways, namely the nuclear factor (NF)-kappaB pathway. In this article, we will focus on the function of the NF-kappaB pathway in liver physiology and pathology. Especially, recent data based on experiments with genetically modified mice will be discussed, which demonstrated important and controversial functions of this pathway e.g. in cytokine-mediated hepatocyte apoptosis, ischemia-reperfusion injury, liver regeneration and the development of hepatocellular carcinoma. Moreover, the role of the interleukin-6 pathway and its possible protective function in the context of liver failure will be summarized.

Evaluation of the role of nuclear factor-kappaB signaling in liver injury using genetic animal models

Most chronic liver diseases are not sufficiently treatable at present and very often progress to liver fibrosis and liver cirrhosis. Several recent studies have suggested that cytokines and cytokine-activated inflammatory signaling pathways might play an important role in the mediation of liver injury. Although pro-inflammatory signaling pathways such as nuclear factor (NF)-kappaB have evolved primarily for host defense to infections, they appear to be involved in the pathogenesis of inflammatory diseases and may mediate liver injury in response to a variety of agents and pathogens. Herein is summarized briefly some recent findings concerning the role of NF-kappaB in different models of liver injury based on transgenic and knockout animal technology.

Renewed interest in cancer immunotherapy with the tumor necrosis factor superfamily molecules

Molecules belonging to the Tumor Necrosis Factor (TNF) and TNF receptor superfamilies have explosively expanded through the era of genomics and bioinformatics. Biological investigations of these molecules have explored their potency as attractive targets for cancer therapy. Anti-tumor mechanisms mediated by TNF superfamily molecules (TNFSF) could be classified into direct actions onto tumor cells and indirect effects through immune or non-immune components of tumor-bearing host. In this review, we focus on TRAIL, CD40, 4-1BB (CD137), and LIGHT as promising molecules to mediate powerful and selective anti-tumor responses, and summarize their unique effector mechanisms. In addition, optimal approaches to manipulate these molecules for cancer therapy are also discussed. We try to provide an insight into a role of TNFSF in cancer therapeutics and highlight each of their potency to be an important player in anti-cancer strategies.

A mutated human tumor necrosis factor-alpha improves the therapeutic index in vitro and in vivo

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) is a multifunctional cytokine that has cytotoxic, cytostatic and immunomodulatory effects on malignant tumors. However, clinical trials have revealed high systemic toxicity and this has hampered its utilization as an anti-cancer agent. In this study, a human TNF-alpha mutant was created and tested for its anti-tumor effects.

METHODS

The TNF mutant (recombinant mutated human TNF; rmhTNF) was prepared by protein engineering in which amino acids Pro, Ser and Asp at positions 8, 9 and 10 of TNF-alpha were substituted by Arg, Lys and Arg, and C terminal Leu157 was substituted by Phe, along with deletion of the first seven N-terminal amino acids. Prokaryotic expression recombinant vector pBV-mhTNF containing the PLPR promotor was constructed and transformed into E. coli DH5alpha. The rmhTNF was expressed in a partially soluble form in DH5alpha, purified from the supernatant of cell lysate by ammonia sulfate precipitation and two sequential chromatographic steps.

RESULTS

The purified rmhTNF was >95% pure by SDS-PAGE stained with silver and high-pressure size exclusion chromatography (SEC-HPLC). Its yield was about 1.22 mg/g wet cell paste. The mutant rmhTNF exhibited an approximately 50-fold increase in cytotoxicity relative to the wild-type rhTNF on the mouse fibroblast cell line L929 in a standard cytotoxicity test, and at least and at least 50 times higher LD50 as wild type rhTNF in mice. In vivo biological activity studies carried out on tumor cell transplanted mice and nude mice also showed a more effective cytotoxicity of rmhTNF than rhTNF.

DISCUSSION

These results suggest that rmhTNF has potential for developing an effective anti-tumor reagent for some tumors.

Caspase 8 is absent or low in many ex vivo gliomas

BACKGROUND

Better treatments are required urgently for patients with malignant glioma, which currently is incurable. Death ligands, such as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), may offer promise for the treatment high-grade glioma if such ligands induce apoptotic signaling in vivo in glioma cells. Caspase 8 is required for death ligand signaling, and its levels may influence the sensitivity of glioma cells to death ligands. It also may act as a tumor suppressor protein. The authors analyzed caspase 8 expression levels in ex vivo glioma specimens and explored potential mechanisms of its regulation.

METHODS

Eleven glioblastomas, 5 anaplastic astrocytomas, and 3 low-grade astrocytomas were studied. The levels of caspase 8, caspase 10, cellular FLICE inhibitory protein (c-FLIP), and signal transducer and activator of transcription (STAT)-1 were assayed using quantitative immunoblotting. Caspase 8 mRNA was measured by Northern blot analysis. The methylation status of the caspase 8 gene was determined by bisulfate modification of genomic DNA, cloning, and sequencing. Statistical analyses were performed using nonparametric (Spearman) correlations.

RESULTS

Some ex vivo glioma samples lacked detectable caspase 8, with many expressing barely detectable levels. No tumors expressed significant amounts of caspase 10 or c-FLIP. A strong association was found between caspase 8 mRNA and protein levels. Neither expression of the transcription factor STAT-1 nor caspase 8 gene methylation correlated with caspase 8 levels.

CONCLUSIONS

The absence of caspase 8 protein in many resected glioma samples implied that many patients with glioma may not benefit from death ligand-based treatments, unless caspase 8 (or caspase 10) protein expression can be elevated. Demethylating agents are unlikely to boost caspase 8 levels in glioma cells, but treatments that increase caspase 8 mRNA levels may up-regulate expression of the protein.

Optimization of protein therapies by polymer-conjugation as an effective DDS

Due to recent advances in disease proteomics, many disease-related proteins have been found. It is expected that there will be therapeutically useful proteins among them. However, it is clinically difficult to use most proteins as effective and safe drugs because of their very low stability and pleiotropic actions in vivo. To promote disease proteomic based drug development for protein therapies, we have attempted to develop an optimal polymer-conjugation system for improving the therapeutic potency of proteins. In this review, we introduce this innovative protein-drug system.

Functionalization of Tumor Necrosis Factor-α Using Phage Display Technique and PEGylation Improves Its Antitumor Therapeutic Window

PURPOSE

In this study, the optimization of antitumor therapy with tumor necrosis factor-alpha (TNF-alpha) was attempted.

EXPERIMENTAL DESIGN

Using the phage display technique, we created a lysine-deficient mutant TNF-alpha (mTNF-K90R). This mutant had higher affinities to both TNF receptors, despite reports that certain lysine residues play important roles in trimer formation and receptor binding.

RESULTS

The mTNF-K90R showed an in vivo therapeutic window that was 13-fold higher than that of the wild-type TNF-alpha (wTNF-alpha). This was due to the synergistic effect of its 6-fold stronger in vitro bioactivity and its 2-fold longer plasma half-life derived from its surface negative potential. The reason why the mTNF-K90R showed a higher bioactivity was understood by a molecular modeling analysis of the complex between the wTNF-alpha and TNF receptor-I. The mTNF-K90R, which was site-specifically mono-PEGylated at the NH2 terminus (sp-PEG-mTNF-K90R), had a higher in vitro bioactivity and considerably longer plasma half-life than the wTNF-alpha, whereas the randomly mono-PEGylated wTNF-alpha had 6% of the bioactivity of the wTNF-alpha. With regard to effectiveness and safety, the in vivo antitumor therapeutic window of the sp-PEG-mTNF-K90R was 60-fold wider than that of the wTNF-alpha.

CONCLUSIONS

These results indicated that this functionalized TNF-alpha may be useful not only as an antitumor agent but also as a selective enhancer of vascular permeability in tumors for improving antitumor chemotherapy.

Development of Novel DDS Technologies for Pharmacoproteomic-based Drug Discovery and Development

With the success of the Human Genome Project, the focus of life science research has shifted to the functional and structural analyses of proteins, such as proteomics and structural genomics. These novel approaches to the analysis of proteins, including newly identified ones, are expected to help in the identification and development of protein therapies for various diseases. Thus pharmacoproteomic-based drug discovery currently has a very high profile. Nevertheless, the use of bioactive proteins in the clinical setting is not straightforward because in vivo these proteins have low stability and pleiotropic action. To promote pharmacoproteomic-based drug discovery and development, we have attempted to establish a system for creating functional mutant proteins (muteins) with the desired properties and to develop a site-specific bioconjugation system for further improving their therapeutic potency. These innovative protein-drug systems are discussed in this review.

Creation of Functional Muteins Using Phage Libraries for Pharmacoproteomic-based Drug Discovery and Development of DDS

Tumor necrosis factor-alpha (TNF-alpha) has been expected to be a promising new antitumor agent, but toxic side effects by the systemic administration of TNF-alpha limit its clinical application. In this study, we attempted to improve the therapeutic potency of TNF-alpha by using our protein-drug innovation systems. Among phage libraries displaying various mutant TNF-alphas, we isolated some lysine-deficient super mutant TNF-alphas, typified by mTNF-alpha-K90R, with higher TNF-receptor affinities and stronger bioactivity in vitro, in spite of the importance of lysine residues for trimer formation and receptor binding. mTNF-alpha-K90R showed more than 10 times stronger in vivo antitumor effects and 1.3 times less toxicity than wild-type TNF-alpha (wTNF-alpha). Site-specifically mono-PEGylated mTNF-alpha-K90R (sp-PEG-mTNF-alpha-K90R) at N-terminus showed higher in vitro bioactivity than unmodified wTNF-alpha, whereas randomly mono-PEGylated wTNF-alpha at a lysine residue (ran-PEG-wTNF-alpha) had less than 6% of the bioactivity of wTNF-alpha. The antitumor therapeutic window of sp-PEG-mTNF-alpha-K90R was extended by about 5 times, 60 times and 18 times compared with those of mTNF-alpha-K90R, wTNF-alpha and ran-PEG-wTNF-alpha, respectively. sp-PEG-mTNF-alpha-K90R may, thus, be a potential systemic anti-tumor therapeutic agent. These data suggested that our fusion protein-drug innovation system composed of a creation system of functional mutant proteins based on phage display technique and a site-specific PEGylation system may open up a new avenue to the optimal protein therapy.

Optimal site-specific PEGylation of mutant TNF-α improves its antitumor potency

Recently, we created a lysine-deficient mutant tumor necrosis factor-alpha [mTNF-alpha-Lys(-)] with full bioactivity in vitro compared with wild-type TNF-alpha (wTNF-alpha), and site-specific PEGylation of mTNF-alpha-Lys(-) was found to selectively enhance its in vivo antitumor activity. In this study, we attempted to optimize this PEGylation of mTNF-alpha-Lys(-) to further improve its therapeutic potency. mTNF-alpha-Lys(-) was site-specifically modified at its N-terminus with linear polyethylene glycol (LPEG) or branched PEG (BPEG). While randomly mono-PEGylated wTNF-alpha (ran-LPEG5K-wTNF-alpha) with 5 kDa of LPEG (LPEG5K) had about only 4% in vitro bioactivity of wTNF-alpha, mono-PEGylated mTNF-alpha-Lys(-) [sp-PEG-mTNF-alpha-Lys(-)] with LPEG5K, LPEG20K, BPEG10K, and BPEG40K had 82%, 58%, 93%, and 65% bioactivities of mTNF-alpha-Lys(-), respectively. sp-LPEG-mTNF-alpha-Lys(-) and sp-BPEG10K-mTNF-alpha-Lys(-) had much superior antitumor activity to those of both unmodified TNF-alphas and ran-LPEG5K-wTNF-alpha, though sp-BPEG40K-mTNF-alpha-Lys(-) did not show in vivo antitumor activity. Thus, the molecular shape and weight of PEG may strongly influence the in vivo antitumor activity of sp-PEG-mTNF-alpha-Lys(-).

Development of Novel Drug Delivery System (DDS) Technologies for Proteomic-Based Drug Development

With the success of human genome projects, the focus of life science research has shifted to the functional and structural analyses of proteins, such as disease proteomics. These structural and functional analyses of expressed proteins in the cells and/or tissues are expected to contribute to the identification of therapeutically applicable proteins for various diseases. Thus, pharmaco-proteomic based drug development for protein therapies is most noticed currently. However, there is a clinical difficulty to use almost bioactive proteins, because of their very low stability and pleiotropic actions in vivo. To promote pharmaco-proteomic based drug development for protein therapies to various diseases, we have attempted to establish a system for creating functional mutant proteins (muteins) with desired properties, and to develop a site-specific polymer-conjugation system for further improving the therapeutic potency of proteins. In this review, we are introducing our original protein-drug innovation systems mentioned above.

Site-specific PEGylation of a lysine-deficient TNF-alpha with full bioactivity

Addition of polyethylene glycol to protein (PEGylation) to improve stability and other characteristics is mostly nonspecific and may occur at all lysine residues, some of which may be within or near an active site. Resultant PEGylated proteins are heterogeneous and can show markedly lower bioactivity. We attempted to develop a strategy for site-specific mono-PEGylation using tumor necrosis factor-alpha (TNF-alpha). We prepared phage libraries expressing TNF-alpha mutants in which all the lysine residues were replaced with other amino acids. A fully bioactive lysine-deficient mutant TNF-alpha (mTNF-alpha-Lys(-)) was isolated by panning against TNF-alpha-neutralizing antibody despite reports that some lysine residues were essential for its bioactivity. mTNF-alpha-Lys(-) was site-specifically mono-PEGylated at its N terminus. This mono-PEGylated mTNF-alpha-Lys(-), with superior molecular uniformity, showed higher bioactivity in vitro and greater antitumor therapeutic potency than randomly mono-PEGylated wild-type TNF-alpha. These results suggest the usefulness of the phage display system for creating functional mutant proteins and of our site-specific PEGylation approach.

Parenchymal, but not leukocyte, TNF receptor 2 mediates T cell-dependent hepatitis in mice

TNF-alpha is a central mediator of T cell activation-induced hepatitis in mice, e.g., induced by Pseudomonas exotoxin A (PEA). In this in vivo mouse model of T cell-dependent hepatitis, liver injury depends on both TNFRs. Whereas TNFR1 can directly mediate hepatocyte death, the in vivo functions of TNFR2 in pathophysiology remained unclear. TNFR2 has been implicated in deleterious leukocyte activation in a transgenic mouse model and in enhancement of TNFR1-mediated cell death in cell lines. In this study, we clarify the role of hepatocyte- vs leukocyte-expressed TNFR2 in T cell-dependent liver injury in vivo, using the PEA-induced hepatitis model. Several types of TNFR2-expressing leukocytes, especially neutrophils and NK cells, accumulated within the liver throughout the pathogenic process. Surprisingly, only parenchymal TNFR2 expression, but not the TNFR2 expression on leukocytes, contributed to PEA-induced hepatitis, as shown by analysis of wild-type --> tnfr2 degrees and the reciprocal mouse bone marrow chimeras. Furthermore, PEA induced NF-kappaB activation and cytokine production in the livers of both wild-type and tnfr2 degrees mice, whereas only primary mouse hepatocytes from wild-type, but not from tnfr2 degrees, mice were susceptible to cell death induced by a combination of agonistic anti-TNFR1 and anti-TNFR2 Abs. Our results suggest that parenchymal, but not leukocyte, TNFR2 mediates T cell-dependent hepatitis in vivo. The activation of leukocytes does not appear to be disturbed by the absence of TNFR2.

Novel synthetic LPS receptor agonists boost systemic and mucosal antibody responses in mice

Safe and cost-effective adjuvants are a critical requirement for subunit vaccine development. We report here the in vivo activity of a series of fully synthetic LPS receptor agonists that have been shown to activate NF-kappaB signaling through the Toll-like receptor 4 (TLR4). These compounds boost antibody responses to protein antigens when coadministered at microgram doses in mice. At these dosage levels no adverse effects are observed. Antibody responses are largely IgG1, with enhanced IgG2a, and down-regulated IgE as compared to alum adjuvanted immunization. Stimulation of Th1 is confirmed by enhanced gamma-interferon production after in vitro antigen restimulation of spleen cells from mice immunized with the synthetic adjuvants. The adjuvants are active by both subcutaneous and intranasal routes of vaccine administration, and in the latter case can amplify both serum IgG and serum and mucosal IgA responses. The compounds must be administered at the same site with antigen to boost anti-vaccine antibody. These fully synthetic ligands of the innate immune system offer the potential for use as effective, safe, and nonbiologically-derived adjuvants.

Enzymic degradation of plasma arginine using arginine deiminase inhibits nitric oxide production and protects mice from the lethal effects of tumour necrosis factor alpha and endotoxin

Septic shock is mediated in part by nitric oxide (NO) and tumour necrosis factor alpha (TNFalpha). NO is synthesized primarily from extracellular arginine. We tested the ability of an arginine-degrading enzyme to inhibit NO production in mice and to protect mice from the hypotension and lethality that occur after the administration of TNFalpha or endotoxin. Treatment of BALB/c mice with arginine deiminase (ADI) formulated with succinimidyl succinimide polyethylene glycol of M(r) 20000 (ADI-SS PEG(20000)) eliminated all measurable plasma arginine (from normal levels of approximately 155 microM arginine to 2 microM). In addition, ADI-SS PEG(20000) also inhibited the production of NO, as quantified by plasma nitrate+nitrite. Treatment of mice with TNFalpha or endotoxin resulted in a dose-dependent increase in NO production and lethality. Pretreatment of mice with ADI-SS PEG(20000) resulted in increased resistance to the lethal effects of TNFalpha and endotoxin. These observations are consistent with NO production resulting, to some extent, from the metabolism of extracellular arginine. The toxic effects of TNFalpha and endotoxin may be partially inhibited by enzymic degradation of plasma arginine by ADI-SS PEG(20000). Interestingly, pretreatment with ADI-SS PEG(20000) did not inhibit the anti-tumour activity of TNFalpha in vitro or in vivo. This treatment may allow greater amounts of TNFalpha, as well as other cytokines, to be administered while abrogating side effects such as hypotension and death.

Selective enhancement of thrombopoietic activity of PEGylated interleukin 6 by a simple procedure using a reversible amino-protective reagent

We developed a novel method for the chemical modification of cytokines with synthetic polymers to increase the therapeutic efficacy of the former in vivo. A pH-reversible amino-protective reagent, dimethylmaleic anhydride (DMMAn), was used for modification of interleukin-6 (IL-6) with polyethylene glycol (PEG). The novel PEG-conjugated IL-6 (DmPEG-IL-6), which had been pretreated with DMMAn before PEGylation, showed up to a 140% increase in in vitro specific activity compared with PEG-IL-6 that had been synthesized by the previous method. Moreover, DmPEG-IL-6 caused thrombopoiesis more potently in mice than PEG-IL-6. The DmPEG-IL-6 Fr.1, having 3-4 PEG chains attached to the cytokine, showed the strongest thrombopoietic effect among the DmPEG-IL-6s with different molecular sizes that were tested. PEG-IL-6 Fr.1 had a 500-fold higher potency in stimulating thrombopoiesis than native IL-6 and DmPEG-IL-6 Fr.1 achieved a threefold higher thrombopoietic effect than PEG-IL-6 Fr.1. In addition, side-effects, such as an increase in the plasma fibrinogen level, were not observed after injection of either PEG-IL-6s or DmPEG-IL-6s. These results suggest that PEGylation with DMMAn pretreatment may become a useful means for clinical cytokine delivery.

Effects of tumor necrosis factor-alpha on basal and stimulated endothelium-dependent vasomotion in human resistance vessel

The aim of this study was to determine whether tumor necrosis factor (TNF)-alpha would impair basal and stimulated endothelium-dependent vasomotion in human resistance vessel. Changes in baseline and acetylcholine (ACh)-induced forearm vascular resistance (FVR) were measured plethysmographically before and after a low-dose intraarterial forearm infusion of TNF-alpha according to the following three protocols in healthy volunteers. In the condition without pretreatment, basal FVR was significantly increased by TNF-alpha (from 30.5 +/- 4.8 to 39.9 +/- 5.9 units; p < 0.01), whereas ACh-induced minimal FVR did not differ between pre- and post-TNF-alpha states. In the condition after pretreatment with the cyclooxygenase inhibitor acetylsalicylic acid, although the vascular effects of TNF-alpha on basal FVR appeared to be blocked (37.1 +/- 5.3 vs. 37.6 +/- 5.2; NS), ACh-induced minimal FVR did not differ between pre- and post-TNF-alpha states. In the condition after pretreatment with the nitric oxide (NO) synthase inhibitor N(G)-monomethyl-L-arginine, the vascular effect of TNF-alpha on basal FVR was diminished, and the ACh-induced maximal dilatory response was significantly blunted after TNF-alpha compared with before TNF-alpha (minimal FVR: 30.4 +/- 12.0 vs. 12.3 +/- 4.2 units; p < 0.05). These findings suggest that brief exposure of the human forearm resistance artery to TNF-alpha may increase basal bioavailability of the vasoconstrictor prostaglandin and reduce basal bioavailability of NO. In the stimulated condition, TNF-alpha-induced vascular dysfunction may be overwhelmed by increased NO bioavailability in healthy humans.

Molecular design of polyvinylpyrrolidone-conjugated interleukin-6 for enhancement of in vivo thrombopoietic activity in mice

Functional polyvinylpyrrolidone (PVP) was synthesized as a novel polymeric modifier for polymer-conjugated cytokines, and its efficiency and applicability as a drug delivery system (DDS) were evaluated. PVP with a carboxyl group at one end of the main chain was prepared by radical polymerization (M(n): 6000, M(w)/M(n): 1.14) with the aid of 4,4'-azobis(4-cyanovaleric acid) as a radical initiator and 3-mercaptopropionic acid as a transfer agent. Interleukin-6 (IL-6) was covalently conjugated via the formation of amino bonds between the lysine amino groups of IL-6 and PVP. PVP-conjugated IL-6, in which 60% of the fourteen lysine amino groups of IL-6 were estimated to be coupled with PVP (M-PVP-IL-6), showed more than 50-fold greater thrombopoietic potency in vivo than native IL-6. No side effects, such as body weight loss, were observed in the M-PVP-IL-6 treated mice. These results indicate that PVP as a polymeric modifier is a promising DDS for clinical application of cytokines and other therapeutic agents.

Tumor necrosis factor alpha in the pathogenesis of human and murine fulminant hepatic failure

BACKGROUND & AIMS

The tumor necrosis factor (TNF)-alpha/TNF receptor system is critical for liver development because hepatocytes undergo apoptosis if the antiapoptotic cascades resulting in RelA NF-kappaB activation are not effective. Therefore, we studied the role of TNF-alpha in fulminant hepatic failure (FHF) and developed a new therapeutic strategy.

METHODS

Serum levels and hepatic expression of TNF-alpha and both TNF receptors were determined by enzyme-linked immunosorbent assay and immunohistochemistry. Adenoviral vectors were constructed expressing dominant-negative proteins interfering with intracellular TNF-alpha-dependent pathways. The relevance of these constructs was studied in primary mouse hepatocytes and in a murine model of FHF.

RESULTS

Serum levels of TNF-alpha and TNF receptors are significantly increased in FHF; this increase correlates with patient prognosis. In livers of patients with FHF, infiltrating mononuclear cells express high amounts of TNF-alpha and hepatocytes overexpress TNF receptor 1 (TNF-R1). Apoptotic hepatocytes are significantly increased in FHF, and there is a strong correlation with TNF-alpha expression, which is even more pronounced in areas of mononuclear infiltrates. In an in vivo FHF model, the Fas-associated death domain (FADD), adenovirus selectively blocked the intracellular pathway, leading to mitochondrial cytochrome c release, caspase-3 activation, and, thus, apoptosis of hepatocytes.

CONCLUSIONS

The results show that the TNF-alpha/TNF-R1 system is involved in the pathogenesis of FHF in humans. Studies in this animal model indicate that FADD may serve as a molecular target to prevent liver cell death in vivo.