In situ vaccination against a non-immunogenic tumour using intratumoural injections of liposomal interleukin 2

Revitalizing Cytokine-Based Cancer Immunotherapy through Advanced Delivery Systems

Cytokines can coordinate robust immune responses, holding great promise as therapeutics against infections, autoimmune diseases, and cancers. In cancer treatment, numerous pro-inflammatory cytokines have displayed promising efficacy in preclinical studies. However, their clinical application is hindered by poor pharmacokinetics, significant toxicity and unsatisfactory anticancer efficacy. Thus, while IFN-α and IL-2 are approved for specific cancer treatments, other cytokines still remain subject of intense investigation. To accelerate the application of cytokines as cancer immunotherapeutics, strategies need to be directed to improve their safety and anticancer performance. In this regard, delivery systems could be used to generate innovative therapies by targeting the cytokines or nucleic acids, such as DNA and mRNA, encoding the cytokines to tumor tissues. This review centers on these innovative delivery strategies for cytokines, summarizing key approaches, such as gene delivery and protein delivery, and critically examining their potential and challenges for clinical translation.

Enhanced antitumor efficacy of glutathione-responsive chitosan based nanoparticles through co-delivery of chemotherapeutics, genes, and immune agents

To achieve the co-delivery of chemotherapeutic drugs, genes, and immune agents in a single nanoparticulate system, p-mercaptobenzoic acid-grafted N, N, N-trimethyl chitosan nanoparticles (MT NPs) were successfully synthesized. Paclitaxel (PTX) was encapsulated into the hydrophobic core of the MT NPs, and meanwhile, survivin shRNA-expressing plasmid (iSur-pDNA) and recombinant human interleukin-2 (rhIL-2) were loaded onto the hydrophilic shell of the MT NPs. Owing to the redox-sensitiveness of MT NPs, a rapid release of PTX was triggered by the high concentration of glutathione. The synergistic effects of PTX (1.5 mg/kg), iSur-pDNA (1.875 mg/kg), and rhIL-2 (6 × 10⁵ IU/kg) at a low dose endowed the MT/PTX/pDNA/rhIL-2 NPs with enhanced antitumor efficacies and improved tumor-induced immunosuppression. These results demonstrated that the co-delivery of PTX, iSur-pDNA, and rhIL-2 by the amphiphilic chitosan based NPs with redox-sensitiveness could be a promising strategy in the treatment of tumors.

Combination Immunotherapy With LIGHT and Interleukin-2 Increases CD8 Central Memory T-Cells In Vivo

BACKGROUND

The generation of long-term durable tumor immunity and prolonged disease-free survival depends on the ability to generate and support CD8+ central memory T-cells. Microsatellite-stable colon cancer is resistant to currently available immunotherapies; thus, development of novel mechanisms to increase both lymphocyte infiltration and central memory formation are needed to improve outcomes in these patients. We have previously demonstrated that both interleukin-2 (IL-2) and LIGHT (TNFSF14) independently enhance antitumor immune responses and hypothesize that combination immunotherapy may increase the CD8+ central memory T-cell response.

METHODS

Murine colorectal cancer tumors were established in syngeneic mice. Tumors were treated with control, soluble, or liposomal IL-2 at established intervals. A subset of animal tumors overexpressed tumor necrosis superfamily factor LIGHT (TNFSF14). Peripheral blood, splenic, and tumor-infiltrating lymphocytes were isolated for phenotypic studies and flow cytometry.

RESULTS

Tumors exposed to a combination of LIGHT and IL-2 experienced a decrease in tumor size compared with IL-2 alone that was not demonstrated in wild-type tumors or between other treatment groups. Combination exposure also increased splenic central memory CD8+ cells compared with IL-2 administration alone, while not increasing tumor-infiltrating lymphocytes. In the periphery, the combination enhanced levels of circulating CD8 T-cells and central memory T-cells, while also increasing circulating T-regulatory cells.

CONCLUSIONS

Combination of IL-2, whether soluble or liposomal, with exposure to LIGHT results in increased CD8+ central memory cells in the spleen and periphery. New combination immunotherapy strategies that support both effector and memory T-cell functions are critical to enhancing durable antitumor responses and warrant further investigation.

Nanotechnology Solutions for Controlled Cytokine Delivery: An Applied Perspective

Around 200 cytokines with roles in cell signaling have been identified and studied, with the vast majority belonging to the four-α-helix bundle family. These proteins exert their function by binding to specific receptors and are implicated in many diseases. The use of several cytokines as therapeutic targets has been approved by the FDA, however their rapid clearance in vivo still greatly limits their efficacy. Nano-based drug delivery systems have been widely applied in nanomedicine to develop safe, specific and controlled delivery techniques. Nevertheless, each nanomaterial has its own specifications and their suitability towards the biochemical and biophysical properties of the selected drug needs to be determined, weighing in the final choice of the ideal nano drug delivery system. Nanoparticles remain the most used vehicle for cytokine delivery, where polymeric carriers represent the vast majority of the studied systems. Liposomes and gold or silica nanoparticles are also explored and discussed in this review. Additionally, surface functionalization is of great importance to facilitate the attachment of a wide variety of molecules and modify features such as bioavailability. Since the monitoring of cytokine levels has an important role in early clinical diagnosis and for assessing therapeutic efficacy, nanotechnological advances are also valuable for nanosensor development.

Inhibition of Endothelial Cell Differentiation and Proinflammatory Cytokine Production During Angiogenesis by Allyl Isothiocyanate and Phenyl Isothiocyanate

Angiogenesis is a crucial step in the growth and metastasis of cancers. The activation of endothelial cells and their further behavior are very critical during angiogenesis. The authors analyze the effect of allyl isothiocyanate (AITC) and phenyl isothiocyanate (PITC) on angiogenesis in an in vitro model using human umbilical vein endothelial cells (HUVECs). AITC and PITC significantly inhibited endothelial cell migration, invasion, and tube formation. 3H-thymidine proliferation assay showed that AITC and PITC significantly inhibited the proliferation of HUVECs in vitro. The authors also studied the effect of AITC and PITC on the serum cytokine profiles of angiogenesis-induced animals and found that these compounds are highly potent in the downregulation of vascular endothelial growth factor (VEGF) and proinflammatory cytokines such as interleukin (IL)—1β , IL-6, granulocyte macrophage colony-stimulating factor (GM-CSF), and tumor necrosis factor α (TNF-α). Treatment with these compounds showed an elevation in the levels of IL-2 and tissue inhibitor of metalloproteinases (TIMP)—1, which are antiangiogenic factors. Moreover, studies using B16F-10 melanoma cells showed that both AITC and PITC significantly reduced VEGF mRNA expression. These findings suggest that AITC and PITC act as angiogenesis inhibitors through the downregulation of VEGF and proinflammatory cytokines such as IL-1β, IL-6, GM-CSF, and TNF-α and upregulation of IL-2 and TIMP.

Emerging nanotechnologies for cancer immunotherapy

Founded on the growing insight into the complex cancer-immune system interactions, adjuvant immunotherapies are rapidly emerging and being adapted for the treatment of various human malignancies. Immune checkpoint inhibitors, for example, have already shown clinical success. Nevertheless, many approaches are not optimized, require frequent administration, are associated with systemic toxicities and only show modest efficacy as monotherapies. Nanotechnology can potentially enhance the efficacy of such immunotherapies by improving the delivery, retention and release of immunostimulatory agents and biologicals in targeted cell populations and tissues. This review presents the current status and emerging trends in such nanotechnology-based cancer immunotherapies including the role of nanoparticles as carriers of immunomodulators, nanoparticles-based cancer vaccines, and depots for sustained immunostimulation. Also highlighted are key translational challenges and opportunities in this rapidly growing field.

In situ vaccination for the treatment of cancer

Vaccination has had a tremendous impact on human health by harnessing the immune system to prevent and eradicate infectious diseases and this same approach might be used in cancer therapy. Cancer vaccine development has been slowed hindered by the paucity of universal tumor-associated antigens and the difficulty in isolating and preparing individualized vaccines ex vivo. Another approach has been to initiate or stimulate an immune response in situ (at the tumor site) and thus exploit the potentially numerous tumor-associated antigens there. Here, we review the many approaches that have attempted to accomplish effective in situ vaccination, using intratumoral administration of immunomodulators to increase the numbers or activation state of either antigen present cells or T cells within the tumor.

In situ vaccination: Cancer immunotherapy both personalized and off-the-shelf

As cancer immunotherapy continues to benefit from novel approaches which cut immune 'brake pedals' (e.g. anti-PD1 and anti-CTLA4 antibodies) and push immune cell gas pedals (e.g. IL2, and IFNα) there will be increasing need to develop immune 'steering wheels' such as vaccines to guide the immune system specifically toward tumor associated antigens. Two primary hurdles in cancer vaccines have been: identification of universal antigens to be used in 'off-the-shelf' vaccines for common cancers, and 2) logistical hurdles of ex vivo production of individualized whole tumor cell vaccines. Here we summarize approaches using 'in situ vaccination' in which intratumoral administration of off-the-shelf immunomodulators have been developed to specifically induce (or amplify) T cell responses to each patient's individual tumor. Clinical studies have confirmed the induction of systemic immune and clinical responses to such approaches and preclinical models have suggested ways to further potentiate the translation of in situ vaccine trials for our patients.

Stimulating antitumor immunity with nanoparticles

A variety of strategies, have been applied to cancer treatment and the most recent one to become prominent is immunotherapy. This interest has been fostered by the demonstration that the immune system does recognize and often eliminate small tumors but tumors that become clinical problems block antitumor immune responses with immunosuppression orchestrated by the tumor cells. Methods to reverse this tumor-mediated immunosuppression will improve cancer immunotherapy outcomes. The immunostimulatory potential of nanoparticles (NPs), holds promise for cancer treatment. Phagocytes of various types are an important component of both immunosuppression and immunostimulation and phagocytes actively take up NPs of various sorts, so NPs are a natural system to manipulate these key immune regulatory cells. NPs can be engineered with multiple useful therapeutic features, such as various payloads such as antigens and/or immunomodulatory agents including cytokines, ligands for immunostimulatory receptors or antagonists for immunosuppressive receptors. As more is learned about how tumors suppress antitumor immune responses the payload options expand further. Here we review multiple approaches of NP-based cancer therapies to modify the tumor microenvironment and stimulate innate and adaptive immune systems to obtain effective antitumor immune responses.

Combination delivery of TGF-β inhibitor and IL-2 by nanoscale liposomal polymeric gels enhances tumour immunotherapy

The tumour microenvironment thwarts conventional immunotherapy through multiple immunologic mechanisms, such as the secretion of the transforming growth factor-β (TGF-β), which stunts local tumour immune responses. Therefore, high doses of interleukin-2 (IL-2), a conventional cytokine for metastatic melanoma, induces only limited responses. To overcome the immunoinhibitory nature of the tumour microenvironment, we developed nanoscale liposomal polymeric gels (nanolipogels; nLGs) of drug-complexed cyclodextrins and cytokine-encapsulating biodegradable polymers that can deliver small hydrophobic molecular inhibitors and water-soluble protein cytokines in a sustained fashion to the tumour microenvironment. nLGs releasing TGF-β inhibitor and IL-2 significantly delayed tumour growth, increased survival of tumour-bearing mice, and increased the activity of natural killer cells and of intratumoral-activated CD8(+) T-cell infiltration. We demonstrate that the efficacy of nLGs in tumour immunotherapy results from a crucial mechanism involving activation of both innate and adaptive immune responses.

Particle-mediated delivery of cytokines for immunotherapy

The ability of cytokines to direct the immune response to vaccination, infection and tumors has motivated their use in therapy to augment or shape immunity. To avoid toxic side effects associated with systemic cytokine administration, several approaches have been developed using particle-encapsulated cytokines to deliver this cargo to specific cell types and tissues. Initial work used cytokine-loaded particles to deliver proinflammatory cytokines to phagocytes to enhance antimicrobial and antitumor responses. These particles have also been used to create a cytokine depot at a local site to supplement prophylactic or antitumor vaccines or injected directly into solid tumors to activate immune cells to eliminate established tumors. Finally, recent advances have revealed that paracrine delivery of cytokines directly to T cells has the potential to enhance T-cell mediated therapies. The studies reviewed here highlight the progress in the last 30 years that has established the potential of particle-mediated cytokine immunotherapy.

Engineering nano- and microparticles to tune immunity

The immune system can be a cure or cause of disease, fulfilling a protective role in attacking cancer or pathogenic microbes but also causing tissue destruction in autoimmune disorders. Thus, therapies aimed to amplify or suppress immune reactions are of great interest. However, the complex regulation of the immune system, coupled with the potential systemic side effects associated with traditional systemic drug therapies, has presented a major hurdle for the development of successful immunotherapies. Recent progress in the design of synthetic micro- and nano-particles that can target drugs, deliver imaging agents, or stimulate immune cells directly through their physical and chemical properties is leading to new approaches to deliver vaccines, promote immune responses against tumors, and suppress autoimmunity. In addition, novel strategies, such as the use of particle-laden immune cells as living targeting agents for drugs, are providing exciting new approaches for immunotherapy. This progress report describes recent advances in the design of micro- and nano-particles for immunotherapies and diagnostics.

Effect of Thuja occidentalis and its polysaccharide on cell-mediated immune responses and cytokine levels of metastatic tumor-bearing animals

CONTEXT

Tumor microenvironment induces an active immune tolerance and escapes immune surveillance. In order to achieve an effective antitumor immune response, appropriately activated immune cells should maintain their antitumor activity to overcome the immune suppressive tumor microenvironment.

OBJECTIVES

This study focuses on the effect of Thuja occidentalis L. (Cupressaceae) extract and its polysaccharide (TPS) on cell-mediated immune response (CMI) in metastasis bearing mice.

MATERIALS AND METHODS

Metastasis was induced by injecting B16F-10 melanoma cells in mice through the tail vein and effector mechanisms of CMI was studied by analyzing cytotoxic T-lymphocyte (CTL) activity, natural killer (NK) cell activity, antibody-dependent cell-mediated cytotoxicity (ADCC) and antibody-dependent complement-mediated cytotoxicity (ACC). The effect of T. occidentalis and TPS on pro-inflammatory cytokines and tissue inhibitor matrix metalloproteinases (TIMP) levels were also analyzed.

RESULTS AND DISCUSSION

Administration of T. occidentalis and TPS enhanced the NK cell activity, ADCC and ACC much earlier than the control tumor-bearing animals. T. occidentalis and TPS were also found to decrease the elevated level of pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, GM-CSF and tumor necrosis factor (TNF)-α in the serum of metastatic tumor-bearing animals. The level of antitumor factors such as IL-2 and TIMP was elevated by the treatment with T. occidentalis and TPS in the serum, which was lowered in the untreated tumor-bearing animals.

CONCLUSION

This study clearly suggests that T. occidentalis and TPS effectively stimulate cell-mediated immune system and decrease pro-inflammatory cytokines, thereby inhibiting metastasis of tumor cells.

An artificial antigen-presenting cell with paracrine delivery of IL-2 impacts the magnitude and direction of the T cell response

Artificial antigen-presenting cells (aAPCs) are an emerging technology to induce therapeutic cellular immunity without the need for autologous antigen-presenting cells (APCs). To fully replace natural APCs, an optimized aAPC must present antigen (signal 1), provide costimulation (signal 2), and release cytokine (signal 3). Here we demonstrate that the spatial and temporal characteristics of paracrine release of IL-2 from biodegradable polymer aAPCs (now termed paAPCs) can significantly alter the balance in the activation and proliferation of CD8+ and CD4+ T cells. Paracrine delivery of IL-2 upon T cell contact with paAPCs induces significant IL-2 accumulation in the synaptic contact region. This accumulation increases CD25 (the inducible IL-2 Rα chain) on responding T cells and increases proliferation of CD8+ T cells in vitro to levels 10 times that observed with equivalent amounts of bulk IL-2. These CD8+ T cell responses critically depend upon close contact of T cells and the paAPCs and require sustained release of low levels of IL-2. The same conditions promote activation-induced cell death in CD4+ T cells. These findings provide insight into the response of T cell subsets to paracrine IL-2.

Nomilin inhibits tumor-specific angiogenesis by downregulating VEGF, NO and proinflammatory cytokine profile and also by inhibiting the activation of MMP-2 and MMP-9

Angiogenesis is a crucial step in the growth and metastasis of cancers. Antiangiogenic activity of nomilin was studied using in vivo as well as in vitro models. Nomilin significantly inhibited tumor directed capillary formation. Serum proinflammatory cytokines such as IL-1β, IL-6, TNF-α and GM-CSF and also serum NO levels were significantly reduced by the treatment of nomilin. Administration of nomilin significantly reduced the serum level of VEGF, a proangiogenic factor and increased the antiangiogenic factors IL-2 and TIMP-1. In vitro studies using rat aortic ring assay showed that administration of nomilin at non-toxic concentrations significantly inhibited microvessel sprouting. Studies using human umbilical vein endothelial cells clearly demonstrated that administration of nomilin significantly retarded endothelial cell proliferation, migration, invasion and tube formation. These data clearly demonstrate the antiangiogenic potential of nomilin by downregulating the activation of MMPs, production of VEGF, NO and proinflammatory cytokines as well as upregulating IL-2 and TIMP.

Induction of potent anti-tumor responses while eliminating systemic side effects via liposome-anchored combinatorial immunotherapy

Immunostimulatory therapies that activate immune response pathways are of great interest for overcoming the immunosuppression present in advanced tumors. Agonistic anti-CD40 antibodies and CpG oligonucleotides have previously demonstrated potent, synergistic anti-tumor effects, but their clinical use even as monotherapies is hampered by dose-limiting inflammatory toxicity provoked upon systemic exposure. We hypothesized that by anchoring immuno-agonist compounds to lipid nanoparticles we could retain the bioactivity of therapeutics in the local tumor tissue and tumor-draining lymph node, but limit systemic exposure to these potent molecules. We prepared PEGylated liposomes bearing surface-conjugated anti-CD40 and CpG and assessed their therapeutic efficacy and systemic toxicity compared to soluble versions of the same immuno-agonists, injected intratumorally in the B16F10 murine model of melanoma. Anti-CD40/CpG-liposomes significantly inhibited tumor growth and induced a survival benefit similar to locally injected soluble anti-CD40 + CpG. Biodistribution analyses following local delivery showed that the liposomal carriers successfully sequestered anti-CD40 and CpG in vivo, reducing leakage into systemic circulation while allowing draining to the tumor-proximal lymph node. Contrary to locally-administered soluble immunotherapy, anti-CD40/CpG-liposomes did not elicit significant increases in serum levels of ALT enzyme, systemic inflammatory cytokines, or overall weight loss, confirming that off-target inflammatory effects had been minimized. The development of a delivery strategy capable of inducing robust anti-tumor responses concurrent with minimal systemic side effects is crucial for the continued progress of potent immunotherapies toward widespread clinical translation.

Survival after intratumoral interleukin-2 treatment of 72 melanoma patients and response upon the first chemotherapy during follow-up

Systemic high-dose interleukin-2 (IL-2) treatment achieves long-term survival in a subset of advanced patients with melanoma. As we reported previously, intratumoral IL-2 induced complete local responses in more than 60% of melanoma patients. This study aimed to analyze the long-term outcome of 72 patients treated in two prior trials. Melanoma patients (49 stage III, 23 stage IV) with injectable metastases received intratumoral IL-2 injections thrice weekly at individually escalated doses (median duration, 6.5 weeks; median total IL-2 dose, 72 MIU; median number of injected metastases, 10). The observed 2-year overall survival rates were 95.5% for stage III patients with cutaneous metastases only (stage IIIB), 72% for those with combined cutaneous and lymph node involvement (stage IIIC), 66.7% for stage IV patients with disease limited to distant soft-tissue metastases (stage IV M1a), and 9.1% for those with visceral metastases (stage IV M1b and stage IV M1c). Thirty patients who reported recurrence of unresectable distant metastases subsequently received chemotherapy in the further course of disease and showed an overall response rate of 36.7% (16.7% complete responses, 20% partial responses). A high total dose of IL-2 and a dacarbazine/temozolomide-based chemotherapy regimen were variables correlated with a clinical response. In conclusion, patients with cutaneous metastasis without lymph node involvement in stage III and with soft-tissue metastasis without visceral involvement in stage IV showed unexpected favorable survival rates after intratumoral treatment with IL-2. Furthermore, the intratumoral IL-2 treatment seemed to be associated with increased complete and partial responses in subsequent chemotherapies.

Anti-angiogenic activity of Ipomoea obscura extract and Ipobscurine-A

OBJECTIVE

Ipomoea obscura (L.) Ker-Gawl, is a medicinal herb with indole alkaloids as an active constituent. In this study, we investigated the anti-angiogenic activity of I. obscura extract and one of its major compounds Ipobscurine-A (IPO-A).

METHODS

In vivo angiogenesis was induced by injecting B16F10 melanoma cells intradermally on the shaven ventral skin of C57BL/6 mice. In vitro experiments were conducted using human umbilical vein endothelial cells.

RESULTS

I. obscura and IPO-A significantly inhibited endothelial cell proliferation, migration, invasion, and tube formation in vitro. Vascular endothelial growth factor (VEGF)-induced sprouting of endothelial cells from rat aorta ex vivo was also inhibited. A marked decrease in the production of matrix metalloproteinases (MMPs) and the expressions of VEGF, cyclooxygenase-2, and nitric oxide synthase by B16F10 cells were observed after the treatment with the extract or IPO-A. Intraperitoneal administration of the extract significantly inhibited B16F10 melanoma cell line-induced neo-vessel formation in C57BL/6 mice in vivo. Analysis of serum cytokine profile clearly showed that extract significantly reduced the elevated levels of pro-inflammatory cytokines such as interleukins (IL)-1β, IL-6, tumor necrosis factor-α, and granulocyte-monocyte colony stimulating factor and the most potent angiogenic factor VEGF in animals. Serum NO level was also found to be significantly lowered by the administration of the extract. Anti-angiogenic factors such as TIMP-1 and IL-2 level were elevated in the extract-treated animals.

CONCLUSION

These data clearly demonstrate that I. obscura extract and IPO-A inhibit the tumor-specific angiogenesis by downregulating pro-angiogenic factors such as MMP, VEGF, and pro-inflammatory mediators and upregulating anti-angiogenic factors such as IL-2 and TIMP-1.

Antiangiogenic activity of ursolic acid

Angiogenesis, the formation of new capillaries from preexisting vessels, is essential for tumor progression. Ursolic acid inhibited the tumor-associated capillary formation in C57BL/6 mice induced by highly metastatic B16F-10 melanoma cells. The levels of serum vascular endothelial growth factor (VEGF), NO, and proinflammatory cytokines were significantly reduced in ursolic acid-treated animals compared with those in control animals. The diminished expressions of VEGF and iNOS genes in B16F-10 melanoma cells treated with nontoxic concentrations of ursolic acid support these observations; the serum TIMP-1 (tissue inhibitor of metalloproteinase-1) and IL-2 (interleukin-2) levels were significantly elevated after the ursolic acid treatment. Nontoxic concentrations of ursolic acid toward human umbilical vein endothelial cells (HUVEC) were determined by MTT (methylthiazol tetrazolium) assay, and these nontoxic concentrations were selected for the in vitro studies. Nontoxic concentrations of ursolic acid inhibited vessel growth from the rat aortic ring. (3)H-thymidine proliferation assay clearly showed the inhibitory effect of ursolic acid on the proliferation of HUVECs in vitro. Ursolic acid significantly inhibited endothelial cell migration and invasion. The role of metalloproteinases has been shown to be important in angiogenesis; therefore, gelatin zymography was performed to determine whether ursolic acid affected protease activity. Gelatin zymographic analysis showed the inhibitory effect of ursolic acid on the protein expression of matrix metalloproteinases MMP-2 and MMP-9. The above observation shows the antiangiogenic activity of ursolic acid.

(+)-Catechin inhibits tumour angiogenesis and regulates the production of nitric oxide and TNF-α in LPS-stimulated macrophages

The anti-angiogenic activity of (+)-catechin as well as its regulatory effect on the production of nitric oxide and TNFα were studied using in vivo and in vitro models. In vivo angiogenic activity was studied using B16F-10 melanoma cell-induced capillary formation in C57BL/6 mice. Administration of (+)-catechin significantly inhibited (36.09%) the number of tumour-directed capillaries induced by injecting B16F-10 melanoma cells on the ventral side of C57BL/6 mice. The cytokine profile in the serum of these animals showed a drastically increased level of proinflammatory cytokines such as IL-1β, IL-6, TNF-α, GM-CSF and the direct endothelial cell proliferating agent, VEGF. Administration of (+)-catechin could differentially regulate elevation of these cytokines. The differential elevation is further evidenced by the increased production of IL-2 and tissue inhibitor of metalloproteinase-1 (TIMP-1) in the B16F-10 injected, (+)-catechin-treated animals. In vitro L929 bioassay revealed the inhibition of TNF-α production by (+)-catechin treatment. In the rat aortic ring assay, (+)-catechin inhibited the microvessel outgrowth at non-toxic concentrations. (+)-Catechin at non-toxic concentrations (5—25 µg/ml) showed significant inhibition in the proliferation, migration and tube formation of endothelial cells, which are the key events in the process of angiogenesis. (+)-Catechin also showed inhibitory effect on VEGF mRNA levels in B16F-10 melanoma cells. (+)-Catechin inhibited the production of NO and TNF-α in LPS-stimulated primary macrophages. Taken together, these results demonstrate that (+)-catechin inhibits tumour-specific angiogenesis by regulating the production of pro- and anti-angiogenic factors such as pro-inflammatory cytokines, nitric oxide, VEGF, IL-2 and TIMP-1. These results also suggest that (+)-catechin could significantly inhibit nitrite and TNF-α production in LPS-stimulated macrophages.

Intratumoral immunocytokine treatment results in enhanced antitumor effects

Immunocytokines (IC), consisting of tumor-specific monoclonal antibodies fused to the immunostimulatory cytokine interleukin 2 (IL2), exert significant antitumor effects in several murine tumor models. We investigated whether intratumoral (IT) administration of IC provided enhanced antitumor effects against subcutaneous tumors. Three unique ICs (huKS-IL2, hu14.18-IL2, and GcT84.66-IL2) were administered systemically or IT to evaluate their antitumor effects against tumors expressing the appropriate IC-targeted tumor antigens. The effect of IT injection of the primary tumor on a distant tumor was also evaluated. Here, we show that IT injection of IC resulted in enhanced antitumor effects against B16-KSA melanoma, NXS2 neuroblastoma, and human M21 melanoma xenografts when compared to intravenous (IV) IC injection. Resolution of both primary and distant subcutaneous tumors and a tumor-specific memory response were demonstrated following IT treatment in immunocompetent mice bearing NXS2 tumors. The IT effect of huKS-IL2 IC was antigen-specific, enhanced compared to IL2 alone, and dose-dependent. Hu14.18-IL2 also showed greater IT effects than IL2 alone. The antitumor effect of IT IC did not always require T cells since IT IC induced antitumor effects against tumors in both SCID and nude mice. Localization studies using radiolabeled (111)In-GcT84.66-IL2 IC confirmed that IT injection resulted in a higher concentration of IC at the tumor site than IV administration. In conclusion, we suggest that IT IC is more effective than IV administration against palpable tumors. Further testing is required to determine how to potentially incorporate IT administration of IC into an antitumor regimen that optimizes local and systemic anticancer therapy.

Antiangiogenic activity of Diallyl Sulfide (DAS)

Antiangiogenic activity of Diallyl sulfide (DAS) was studied using in vivo as well as in vitro models. In vivo antiangiogenic activity was studied using B16F-10 melanoma cell induced capillary formation in C57BL/6 mice. DAS significantly inhibited tumour directed capillary formation. Studies of serum cytokine profile of angiogenesis induced animals clearly showed that DAS significantly reduced the production of proinflammatory cytokines such as IL-1beta, IL-6, TNF-alpha and GM-CSF which are known proangiogenic factors. The serum level of VEGF, an important proangiogenic factor, in angiogenesis induced animals was found to be significantly reduced upon treatment with DAS which may be due to its efficacy in the down regulation of VEGF mRNA expression. Administration of DAS significantly enhanced the production of antiangiogenic factors such as IL-2 and TIMP. In vitro studies using rat aortic ring assay showed that administration of DAS at no n-toxic concentrations significantly inhibited microvessel sprouting. Studies using Human umbilical vein endothelial cells (HUVECs) clearly demonstrated that administration of DAS significantly retarded endothelial cell proliferation, migration, invasion and tube formation. These data clearly suggests that antiangiogenic activity of DAS can be related to its negative regulation of proangiogenic factors such as VEGF and proinflammatory cytokines and positive regulation of antiangiogenic factors such as IL-2 and TIMP.

Antiangiogenic activity of Andrographis paniculata extract and andrographolide

Inhibition of angiogenesis is currently perceived as one of the promising strategies in the treatment of cancer. In this study we analyzed the antiangiogenic activity of Andrographis paniculata extract (APE) and its major component andrographolide (ANDLE) using both in vitro and in vivo models. Intraperitoneal administration of APE and ANDLE significantly inhibited the B16F-10 melanoma cell line induced capillary formation in C57BL/6 mice. Analysis of serum cytokine profile showed a drastic elevation in the proinflammatory cytokines such as IL-1beta, IL-6, TNF-alpha and GM-CSF and the most potent angiogenic factor VEGF in angiogenesis induced animals. Treatment of APE and ANDLE significantly reduced this elevated levels. Moreover, VEGF mRNA level in B16F-10 cell line showed a reduced level of expression in the presence of APE and ANDLE. Serum NO level which was increased in B16F-10 melanoma injected control animals was also found to be significantly lowered by the administration of APE and ANDLE. Antiangiogenic factors such as TIMP-1 and IL-2 level was elevated in APE and ANDLE treated angiogenesis induced animals. In the rat aortic ring assay APE and ANDLE inhibited the microvessel outgrowth at non toxic concentrations. Taken together our results demonstrate that APE and ANDLE inhibit the tumor specific angiogenesis by regulating the production of various pro and antiangiogenic factors such as proinflammatory cytokine, nitric oxide, VEGF, IL-2 and TIMP-1.

Piper longum inhibits VEGF and proinflammatory cytokines and tumor-induced angiogenesis in C57BL/6 mice

The antiangiogenic activity of Piper longum was studied using in vivo as well as in vitro models. In vivo, antiangiogenic activity was studied using B16F-10 melanoma cell-induced capillary formation in C57BL/6 mice. Intraperitoneal administration of the extract (10 mg/dose/animal) significantly inhibited (50.6%) the number of tumor-directed capillaries induced by injecting B16F-10 melanoma cells on the ventral side of C57BL/6 mice. The cytokine profile in the serum of these animals showed a drastically increased level of proinflammatory cytokines such as IL-1beta, IL-6, TNF-alpha, GM-CSF and the direct endothelial cell proliferating agent, VEGF. Administration of the methanolic extract of P. longum could differentially regulate the level of these cytokines. The level of IL-2 and tissue inhibitor of metalloprotease-1 (TIMP-1) was increased significantly when the angiogenesis-induced animals were treated with the extract. The extract of P. longum at non-toxic concentrations (10 microg/ml, 5 microg/ml, 1 microg/ml) inhibited the VEGF-induced vessel sprouting in rat aortic ring assay. Moreover, P. longum was able to inhibit the VEGF-induced proliferation, cell migration and capillary-like tube formation of primary cultured human endothelial cells. Hence, the observed antiangiogenic activity of the plant P. longum is related to the regulation of these cytokines and growth factors in angiogenesis-induced animals.

Pharmacokinetics and in vitro and in vivo anti-tumor response of an interleukin-2-human serum albumin fusion protein in mice

PURPOSE

Albuleukin fusion protein is a recombinant human interleukin-2 (rIL-2) genetically fused to recombinant human serum albumin (rHSA). The pharmacokinetics and pharmacologic activity of Albuleukin were examined in mice to determine whether the fusion protein had the immunomodulatory and anti-tumor properties of rIL-2 as well as a prolonged serum half-life due to the rHSA.

METHODS

The effect of Albuleukin on lymphocyte proliferation, IL-2 receptor binding, and release of IFN-gamma from human NK cells were examined in vitro. For the pharmacokinetic analysis, Albuleukin and rIL-2 were administered intravenously (i.v.) and subcutaneously (s.c.) to BALB/c mice, both at a single dose of 500 microg/kg. The anti-tumor properties of Albuleukin were evaluated in a Renca tumor model in BALB/c mice and in a metastatic liver model of B16F10 melanoma in C57B1/6 mice. In the Renca tumor model, BALB/c mice were dosed intraperitoneally (i.p.) and s.c. with Albuleukin on days 12, 14, 16, 19, 21, and 23 and i.p. with rIL-2 daily for two periods of 5 days (days 10-14 and 17-21). In the B16 melanoma model, C57B1/6 mice were dosed s.c. with rIL-2 twice daily or Albuleukin every 48 h for 14 days.

RESULTS

In vitro, Albuleukin induced the proliferation of primary human and mouse T cells and B cells and primary human NK cells, competed with rIL-2 for binding to the IL-2 receptors, and induced the production of IFN-gamma from primary human NK cells. The s.c. bioavailability of Albuleukin was about 45% relative to the i.v. dose. Plasma half-life was prolonged and ranged from 6 to 8 h with Albuleukin, compared to 19-57 min with rIL-2. Total clearance of Albuleukin was about 50-fold slower than that of rIL-2 after i.v. dosing. In vivo, Albuleukin suppressed the growth of Renca tumors and induced a dense infiltration of CD4+ and CD8+ T cells. Both Albuleukin and rIL-2 significantly reduced the tumor burden in mice with hepatic B16F10 metastases. Albuleukin significantly reduced the incidence of residual macroscopic hepatic tumors, resulting in improved survival relative to controls and rIL-2.

CONCLUSION

Results from these studies suggest that the therapeutic efficacy of rIL-2 is improved in mice by prolonging its in vivo half-life through genetic fusion to albumin. Albuleukin, the fusion protein, had pronounced anti-tumor effects in Renca and hepatic melanoma tumor models without an increase in mortality. On the basis of its preclinical effects, Albuleukin was brought to the clinic to assess its therapeutic benefit in a variety of cancers.

Effect of Tinospora cordifolia on the cytokine profile of angiogenesis-induced animals

The antiangiogenic activity of Tinospora cordifolia was studied using in vivo as well as in vitro models. In vivo antiangiogenic activity was studied using B16F10 melanoma cell-induced capillary formation in animals. Intraperitoneal administration of the extract at a concentration of 20 mg/kg significantly inhibited the tumour directed capillary formation induced by melanoma cells. Analysis of the serum cytokine profile showed a drastic increase of proinflammatory cytokines such as IL-1beta, IL-6, TNF-alpha, granulocyte monocyte-colony stimulating factor (GM-CSF) and the direct endothelial cell proliferating agent vascular endothelial cell growth factor (VEGF) in the angiogenesis-induced control animals. Administration of Tinospora extract could differentially regulate these cytokine's elevation. The differential regulation is further evidenced by the increased production of antiangiogenic agents IL-2 and tissue inhibitor of metalloprotease-1 (TIMP-1) in the B16F10-injected, extract-treated animals. Moreover, using an in vitro rat aortic ring assay, it was observed that the extract at nontoxic concentrations inhibited the production of proangiogenic factors from B16F10 melanoma cells. Direct treatment of the extract also inhibits the microvessel outgrowth from the aortic ring. Hence, the observed antiangiogenic activity of the plant T. cordifolia is related, at least in part, to the regulation of the levels of these cytokines and growth factors in the blood of the angiogenesis-induced animal.