Combination of temozolomide with immunocytokine F16-IL2 for the treatment of glioblastoma

Tenascin-C targeting strategies in cancer

Tenascin-C (TNC) is a matricellular and multimodular glycoprotein highly expressed under pathological conditions, especially in cancer and chronic inflammatory diseases. Since a long time TNC is considered as a promising target for diagnostic and therapeutic approaches in anti-cancer treatments and was already extensively targeted in clinical trials on cancer patients. This review provides an overview of the current most advanced strategies used for TNC detection and anti-TNC theranostic approaches including some advanced clinical strategies. We also discuss novel treatment protocols, where targeting immune modulating functions of TNC could be center stage.

Clinical advances in TNC delivery vectors and their conjugate agents

Tenascin C (TNC), a glycoprotein that is abundant in the tumor extracellular matrix (ECM), is strongly overexpressed in tumor tissues but virtually undetectable in most normal tissues. Many TNC antibodies, peptides, aptamers, and nanobodies have been investigated as delivery vectors, including 20A1, α-A2, α-A3, α-IIIB, α-D, BC-2, BC-4 BC-8, 81C6, ch81C6, F16, FHK, Ft, Ft-NP, G11, G11-iRGD, GBI-10, 19H12, J1/TN1, J1/TN2, J1/TN3, J1/TN4, J1/TN5, NJT3, NJT4, NJT6, P12, PL1, PL3, R6N, SMART, ST2146, ST2485, TN11, TN12, TNFnA1A2-Fc, TNfnA1D-Fc, TNfnBD-Fc, TNFnCD-Fc, TNfnD6-Fc, TNfn78-Fc, TTA1, TTA1.1, and TTA1.2. In particular, BC-2, BC-4, 81C6, ch81C6, F16, FHK, G11, PL1, PL3, R6N, ST2146, TN11, and TN12 have been tested in human tissues. G11-iRGD and simultaneous multiple aptamers and arginine-glycine-aspartic acid (RGD) targeting (SMART) may be assessed in clinical trials because G11, iRGD and AS1411 (SMART components) are already in clinical trials. Many TNC-conjugate agents, including antibody-drug conjugates (ADCs), antibody fragment-drug conjugates (FDCs), immune-stimulating antibody conjugates (ISACs), and radionuclide-drug conjugates (RDCs), have been investigated in preclinical and clinical trials. RDCs investigated in clinical trials include 111In-DTPA-BC-2, 131I-BC-2, 131I-BC-4, 90Y-BC4, 131I81C6, 131I-ch81C6, 211At-ch81C6, F16124I, 131I-tenatumomab, ST2146biot, FDC 131I-F16S1PF(ab')2, and ISAC F16IL2. ADCs (including FHK-SSL-Nav, FHK-NB-DOX, Ft-NP-PTX, and F16*-MMAE) and ISACs (IL12-R6N and 125I-G11-IL2) may enter clinical trials because they contain components of marketed treatments or agents that were investigated in previous clinical studies. This comprehensive review presents historical perspectives on clinical advances in TNC-conjugate agents to provide timely information to facilitate tumor-targeting drug development using TNC.

Targeted Cytokine Delivery for Cancer Treatment: Engineering and Biological Effects

Anti-tumor properties of several cytokines have already been investigated in multiple experiments and clinical trials. However, those studies evidenced substantial toxicities, even at low cytokine doses, and the lack of tumor specificity. These factors significantly limit clinical applications. Due to their high specificity and affinity, tumor-specific monoclonal antibodies or their antigen-binding fragments are capable of delivering fused cytokines to tumors and, therefore, of decreasing the number and severity of side effects, as well as of enhancing the therapeutic index. The present review surveys the actual antibody-cytokine fusion protein (immunocytokine) formats, their targets, mechanisms of action, and anti-tumor and other biological effects. Special attention is paid to the formats designed to prevent the off-target cytokine-receptor interactions, potentially inducing side effects. Here, we describe preclinical and clinical data and the efficacy of the antibody-mediated cytokine delivery approach, either as a single therapy or in combination with other agents.

Matricellular protein tenascin C: Implications in glioma progression, gliomagenesis, and treatment

Matricellular proteins are nonstructural extracellular matrix components that are expressed at low levels in normal adult tissues and are upregulated during development or under pathological conditions. Tenascin C (TNC), a matricellular protein, is a hexameric and multimodular glycoprotein with different molecular forms that is produced by alternative splicing and post-translational modifications. Malignant gliomas are the most common and aggressive primary brain cancer of the central nervous system. Despite continued advances in multimodal therapy, the prognosis of gliomas remains poor. The main reasons for such poor outcomes are the heterogeneity and adaptability caused by the tumor microenvironment and glioma stem cells. It has been shown that TNC is present in the glioma microenvironment and glioma stem cell niches, and that it promotes malignant properties, such as neovascularization, proliferation, invasiveness, and immunomodulation. TNC is abundantly expressed in neural stem cell niches and plays a role in neurogenesis. Notably, there is increasing evidence showing that neural stem cells in the subventricular zone may be the cells of origin of gliomas. Here, we review the evidence regarding the role of TNC in glioma progression, propose a potential association between TNC and gliomagenesis, and summarize its clinical applications. Collectively, TNC is an appealing focus for advancing our understanding of gliomas.

Revisiting the Tenascins: Exploitable as Cancer Targets?

For their full manifestation, tumors require support from the surrounding tumor microenvironment (TME), which includes a specific extracellular matrix (ECM), vasculature, and a variety of non-malignant host cells. Together, these components form a tumor-permissive niche that significantly differs from physiological conditions. While the TME helps to promote tumor progression, its special composition also provides potential targets for anti-cancer therapy. Targeting tumor-specific ECM molecules and stromal cells or disrupting aberrant mesenchyme-cancer communications might normalize the TME and improve cancer treatment outcome. The tenascins are a family of large, multifunctional extracellular glycoproteins consisting of four members. Although each have been described to be expressed in the ECM surrounding cancer cells, tenascin-C and tenascin-W are currently the most promising candidates for exploitability and clinical use as they are highly expressed in various tumor stroma with relatively low abundance in healthy tissues. Here, we review what is known about expression of all four tenascin family members in tumors, followed by a more thorough discussion on tenascin-C and tenascin-W focusing on their oncogenic functions and their potential as diagnostic and/or targetable molecules for anti-cancer treatment purposes.

Using stroma-anchoring cytokines to augment ADCC: a phase 1 trial of F16IL2 and BI 836858 for posttransplant AML relapse

Natural killer (NK) cells are key effectors in cancer immunosurveillance and posttransplant immunity, but deficiency of environmental signals and insufficient tumor recognition may limit their activity. We hypothesized that the antibody-mediated anchoring of interleukin-2 (IL-2) to a spliced isoform of the extracellular matrix (ECM) glycoprotein tenascin-C would potentiate NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC) against leukemic blasts. In this novel-novel combination, dose-escalation phase 1 trial, we enrolled patients with posttransplant acute myeloid leukemia (AML) relapse to evaluate the safety, pharmacokinetics, pharmacodynamics, and preliminary activity of the antibody-cytokine fusion F16IL2 (10-20x106 IU IV, days 1, 8, 15, and 22 of 28-day cycles) in combination with the anti-CD33 antibody BI 836858 (10-40 mg IV, 2 days after each F16IL2 infusion). Among 15 patients (median [range] age, 50 [20-68] years) treated across 4 dose levels (DL), 6 (40%) had received 2 or 3 prior transplantations. The most frequent adverse events were pyrexia, chills and infusion-related reactions, which were manageable, transient and of grade ≤ 2. One dose-limiting toxicity occurred at each of DL 3 (pulmonary edema) and 4 (GVHD). Three objective responses were observed among 7 patients treated at the 2 higher DL, whereas no responses occurred at the 2 starting DL. Combination therapy stimulated the expansion and activation of NK cells, including those expressing the FcγRIIIA/CD16 receptor. ECM-targeted IL-2 combined with anti-CD33 immunotherapy represents an innovative approach associated with acceptable safety and encouraging biologic and clinical activity in posttransplant AML relapse. This trial was registered at EudraCT (2015-004763-37).

Interleukin 2-Based Fusion Proteins for the Treatment of Cancer

Interleukin 2 (IL-2) plays a fundamental role in both immune activation and tolerance and has revolutionized the field of cancer immunotherapy since its discovery. The ability of IL-2 to mediate tumor regression in preclinical and clinical settings led to FDA approval for its use in the treatment of metastatic renal cell carcinoma and metastatic melanoma in the 1990s. Although modest success is observed in the clinic, cancer patients receiving IL-2 therapy experience a wide array of side effects ranging from flu-like symptoms to life-threatening conditions such as vascular leak syndrome. Over the past three decades, efforts have focused on circumventing IL-2-related toxicities by engineering methods to localize IL-2 to the tumor or secondary lymphoid tissue, preferentially activate CD8⁺ T cells and NK cells, and alter pharmacokinetic properties to increase bioavailability. This review summarizes the various IL-2-based strategies that have emerged, with a focus on chimeric fusion methods.

Utilizing Immunocytokines for Cancer Therapy

Cytokine therapy for cancer has indicated efficacy in certain diseases but is generally accompanied by severe toxicity. The field of antibody-cytokine fusion proteins (immunocytokines) arose to target these effector molecules to the tumor environment in order to expand the therapeutic window of cytokine therapy. Pre-clinical evidence has shown the increased efficacy and decreased toxicity of various immunocytokines when compared to their cognate unconjugated cytokine. These anti-tumor properties are markedly enhanced when combined with other treatments such as chemotherapy, radiotherapy, and checkpoint inhibitor antibodies. Clinical trials that have continued to explore the potential of these biologics for cancer therapy have been conducted. This review covers the in vitro, in vivo, and clinical evidence for the application of immunocytokines in immuno-oncology.

Trial Watch: Immunostimulatory cytokines

During the last two decades, a number of approaches for the activation of the immune system against cancer has been developed. These include highly specific interventions, such as monoclonal antibodies, vaccines and cell-based therapies, as well as relatively unselective strategies, such as the systemic administration of adjuvants and immunomodulatory cytokines. Cytokines constitute a huge group of proteins that, taken together, regulate not only virtually all the aspects of innate and cognate immunity, but also several other cellular and organismal functions. Cytokines operate via specific transmembrane receptors that are expressed on the plasma membrane of target cells and, depending on multiple variables, can engage autocrine, paracrine or endocrine signaling pathways. The most appropriate term for defining the cytokine network is “pleiotropic”: cytokines are produced by - and operate on - multiple, often overlapping, cell types, triggering context-depend biological outcomes as diverse as cell proliferation, chemotaxis, differentiation, inflammation, elimination of pathogens and cell death. Moreover, cytokines often induce the release of additional cytokines, thereby engaging self-amplificatory or self-inhibitory signaling cascades. In this Trial Watch, we will summarize the biological properties of cytokines and discuss the progress of ongoing clinical studies evaluating their safety and efficacy as immunomodulatory agents against cancer.

Tenascin-C Function in Glioma: Immunomodulation and Beyond

First identified in the 1980s, tenascin-C (TNC) is a multi-domain extracellular matrix glycoprotein abundantly expressed during the development of multicellular organisms. TNC level is undetectable in most adult tissues but rapidly and transiently induced by a handful of pro-inflammatory cytokines in a variety of pathological conditions including infection, inflammation, fibrosis, and wound healing. Persistent TNC expression is associated with chronic inflammation and many malignancies, including glioma. By interacting with its receptor integrin and a myriad of other binding partners, TNC elicits context- and cell type-dependent function to regulate cell adhesion, migration, proliferation, and angiogenesis. TNC operates as an endogenous activator of toll-like receptor 4 and promotes inflammatory response by inducing the expression of multiple pro-inflammatory factors in innate immune cells such as microglia and macrophages. In addition, TNC drives macrophage differentiation and polarization predominantly towards an M1-like phenotype. In contrast, TNC shows immunosuppressive function in T cells. In glioma, TNC is expressed by tumor cells and stromal cells; high expression of TNC is correlated with tumor progression and poor prognosis. Besides promoting glioma invasion and angiogenesis, TNC has been found to affect the morphology and function of tumor-associated microglia/macrophages in glioma. Clinically, TNC can serve as a biomarker for tumor progression; and TNC antibodies have been utilized as an adjuvant agent to deliver anti-tumor drugs to target glioma. A better mechanistic understanding of how TNC impacts innate and adaptive immunity during tumorigenesis and tumor progression will open new therapeutic avenues to treat brain tumors and other malignancies.

Bi-specific tenascin-C and fibronectin targeted peptide for solid tumor delivery

Oncofetal fibronectin (FN-EDB) and tenascin-C C domain (TNC-C) are nearly absent in extracellular matrix of normal adult tissues but upregulated in malignant tissues. Both FN-EDB and TNC-C are developed as targets of antibody-based therapies. Here we used peptide phage biopanning to identify a novel targeting peptide (PL1, sequence: PPRRGLIKLKTS) that interacts with both FN-EDB and TNC-C. Systemic PL1-functionalized model nanoscale payloads [iron oxide nanoworms (NWs) and metallic silver nanoparticles] homed to glioblastoma (GBM) and prostate carcinoma xenografts, and to non-malignant angiogenic neovessels induced by VEGF-overexpression. Antibody blockage experiments demonstrated that PL1 tumor homing involved interactions with both receptor proteins. Treatment of GBM mice with PL1-targeted model therapeutic nanocarrier (NWs loaded with a proapoptotic peptide) resulted in reduced tumor growth and increased survival, whereas treatment with untargeted particles had no effect. PL1 peptide may have applications as an affinity ligand for delivery of diagnostic and therapeutic compounds to microenvironment of solid tumors.

Antibody-cytokine fusion proteins: A novel class of biopharmaceuticals for the therapy of cancer and of chronic inflammation

Antibody-cytokine fusion proteins represent a novel class of biopharmaceuticals, with the potential to increase the therapeutic index of cytokine 'payloads' and to promote leukocyte infiltration at the site of disease. In this review, we present a survey of immunocytokines that have been used in preclinical models of cancer and in clinical trials. In particular, we highlight how antibody format, choice of target antigen and cytokine engineering, as well as combination strategies, may have a profound impact on therapeutic performance. Moreover, by using anti-inflammatory cytokines, antibody fusion strategies can conveniently be employed for the treatment of auto-immune and chronic inflammatory conditions.

Antibody-cytokine fusion proteins: Biopharmaceuticals with immunomodulatory properties for cancer therapy

Cytokines have long been used for therapeutic applications in cancer patients. Substantial side effects and unfavorable pharmacokinetics limit their application and may prevent dose escalation to therapeutically active regimens. Antibody-cytokine fusion proteins (often referred to as immunocytokines) may help localize immunomodulatory cytokine payloads to the tumor, thereby activating anticancer immune responses. A variety of formats (e.g., intact IgGs or antibody fragments), molecular targets (e.g., extracellular matrix components and cell membrane antigens) and cytokine payloads have been considered for the development of this novel class of biopharmaceuticals. This review presents the basic concepts on the design and engineering of immunocytokines, reviews their potential limitations, points out emerging opportunities and summarizes key features of preclinical and clinical-stage products.

F8-IL10: A New Potential Antirheumatic Drug Evaluated by a PET-Guided Translational Approach

Antibody fragment F8-mediated interleukin 10 (IL10) delivery is a novel treatment for rheumatoid arthritis (RA). F8 binds to the extra-domain-A of fibronectin (ED-A). In this study, in vivo biodistribution and arthritis targeting of radiolabeled F8-IL10 were investigated in RA patients, followed by further animal studies. Therefore, three RA patients (DAS28 > 3.2) received 0.4 mg of 30–74 megabecquerel [¹²⁴I]I–F8–IL10 for PET-CT and blood sampling. In visually identified PET-positive joints, target-to-background was calculated. Healthy mice, rats, and arthritic rats were injected with iodinated F8-IL10 or KSF-IL10 control antibody. Various organs were excised, weighed, and counted for radioactivity. Tissue sections were stained for fibronectin ED-A. In RA patients, [¹²⁴I]I–F8–IL10 was cleared rapidly from the circulation with less than 1% present in blood after 5 min. PET-CT showed targeting in 38 joints (11–15 per patient) and high uptake in the liver and spleen. Mean target-to-background ratios of PET-positive joints were 2.5 ± 1.2, 1.5 times higher for clinically active than clinically silent joints. Biodistribution of radioiodinated F8-IL10 in healthy mice showed no effect of the radioiodination method. [¹²⁴I]I–F8–IL10 joint uptake was also demonstrated in arthritic rats, ∼14-fold higher than that of the control antibody [¹²⁴I]I-KSF-IL10 (p < 0.001). Interestingly, liver and spleen uptake were twice as high in arthritic than in healthy rats and were related to increased (∼7×) fibronectin ED-A expression in these tissues. In conclusion, [¹²⁴I]I–F8–IL10 uptake was observed in arthritic joints in RA patients holding promise for visualization of inflamed joints by PET-CT imaging and therapeutic targeting. Patient observations and, subsequently, arthritic animal studies pointed to awareness of increased [¹²⁴I]I–F8–IL10 uptake in the liver and spleen associated with moderate systemic inflammation. This translational study demonstrated the value of in vivo biodistribution and PET-CT-guided imaging in development of new and potential antirheumatic drugs’.

Anti-cancer Therapies Employing IL-2 Cytokine Tumor Targeting: Contribution of Innate, Adaptive and Immunosuppressive Cells in the Anti-tumor Efficacy

Antibody-cytokine fusion proteins (immunocytokine) exert a potent anti-cancer effect; indeed, they target the immunosuppressive tumor microenvironment (TME) due to a specific anti-tumor antibody linked to immune activating cytokines. Once bound to the target tumor, the interleukin-2 (IL-2) immunocytokines composed of either full antibody or single chain Fv conjugated to IL-2 can promote the in situ recruitment and activation of natural killer (NK) cells and cytotoxic CD8⁺ T lymphocytes (CTL). This recruitment induces a TME switch toward a classical T helper 1 (Th1) anti-tumor immune response, supported by the cross-talk between NK and dendritic cells (DC). Furthermore, some IL-2 immunocytokines have been largely shown to trigger tumor cell killing by antibody dependent cellular cytotoxicity (ADCC), through Fcγ receptors engagement. The modulation of the TME can be also achieved with immunocytokines conjugated with a mutated form of IL-2 that impairs regulatory T (Treg) cell proliferation and activity. Preclinical animal models and more recently phase I/II clinical trials have shown that IL-2 immunocytokines can avoid the severe toxicities of the systemic administration of high doses of soluble IL-2 maintaining the potent anti-tumor effect of this cytokine. Also, very promising results have been reported using IL-2 immunocytokines delivered in combination with other immunocytokines, chemo-, radio-, anti-angiogenic therapies, and blockade of immune checkpoints. Here, we summarize and discuss the most relevant reported studies with a focus on: (a) the effects of IL-2 immunocytokines on innate and adaptive anti-tumor immune cell responses as well as immunosuppressive Treg cells and (b) the approaches to circumvent IL-2-mediated severe toxic side effects.

Function of neuronal nitric oxide synthase enzyme in temozolomide-induced damage of astrocytic tumor cells

Astrocytic tumors, including astrocytomas and glioblastomas, are the most common type of primary brain tumors. Treatment for glioblastomas includes radiotherapy, chemotherapy with temozolomide (TMZ) and surgical ablation. Despite certain therapeutic advances, the survival time of patients is no longer than 12-14 months. Cancer cells overexpress the neuronal isoform of nitric oxide synthase (nNOS). In the present study, it was examined whether the nNOS enzyme serves a role in the damage of astrocytoma (U251MG and U138MG) and glioblastoma (U87MG) cells caused by TMZ. First, TMZ (250 µM) triggered an increase in oxidative stress at 2, 48 and 72 h in the U87MG, U251MG and U138MG cell lines, as revealed by 2',7'-dichlorofluorescin-diacetate assay. The drug also reduced cell viability, as measured by MTT assay. U87MG cells presented a more linear decline in cell viability at time-points 2, 48 and 72 h, compared with the U251MG and U138MG cell lines. The peak of oxidative stress occurred at 48 h. To examine the role of NOS enzymes in the cell damage caused by TMZ, N(ω)-nitro-L-arginine methyl ester (L-NAME) and 7-nitroindazole (7-NI) were used. L-NAME increased the cell damage caused by TMZ while reducing the oxidative stress at 48 h. The preferential nNOS inhibitor 7-NI also improved the TMZ effects. It caused a 12.8% decrease in the viability of TMZ-injured cells. Indeed, 7-NI was more effective than L-NAME in restraining the increase in oxidative stress triggered by TMZ. Silencing nNOS with a synthetic small interfering (si)RNA (siRNAnNOShum_4400) increased by 20% the effects of 250 µM of TMZ on cell viability (P<0.05). Hoechst 33342 nuclear staining confirmed that nNOS knock-down enhanced TMZ injury. In conclusion, our data reveal that nNOS enzymes serve a role in the damage produced by TMZ on astrocytoma and glioblastoma cells. RNA interference with nNOS merits further studies in animal models to disclose its potential use in brain tumor anticancer therapy.

Tumor rim cells: From resistance to vascular targeting agents to complete tumor ablation

Current vascular targeting strategies pursue two main goals: anti-angiogenesis agents aim to halt sprouting and the formation of new blood vessels, while vascular disrupting agents along with coaguligands seek to compromise blood circulation in the vessels. The ultimate goal of such therapies is to deprive tumor cells out of oxygen and nutrients long enough to succumb cancer cells to death. Most of vascular targeting agents presented promising therapeutic potential, but the final goal which is cure is rarely achieved. Nevertheless, in both preclinical and clinical settings, tumors tend to grow back, featuring a highly invasive, metastatic, and extremely resistant form. This review highlights the critical significance of tumor rim cells as the main factor, determining therapy success with vascular targeting agents. We present an overview of different single and combination treatments with vascular targeting agents that enable efficient targeting of tumor rim cells and long-lasting tumor cure. Understanding the nature of tumor rim cells, how they establish, how they manage to survive of vascular targeting agents, and how they contribute in tumor refractoriness, may open new avenues to the development of beneficial strategies, capable to eliminate residual rim cells, and enable tumor ablation once and forever.

Immunocytokines and bispecific antibodies: two complementary strategies for the selective activation of immune cells at the tumor site

The activation of the immune system for a selective removal of tumor cells represents an attractive strategy for the treatment of metastatic malignancies, which cannot be cured by existing methodologies. In this review, we examine the design and therapeutic potential of immunocytokines and bispecific antibodies, two classes of bifunctional products which can selectively activate the immune system at the tumor site. Certain protein engineering aspects, such as the choice of the antibody format, are common to both classes of therapeutic agents and can have a profound impact on tumor homing performance in vivo of individual products. However, immunocytokines and bispecific antibodies display different mechanisms of action. Future research activities will reveal whether an additive of even synergistic benefit can be obtained from the judicious combination of these two types of biopharmaceutical agents.

Merkel cell carcinoma: emerging biology, current approaches, and future directions

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine cutaneous cancer that predominantly occurs in patients who are older, and is associated with a high rate of distant failure and mortality. Current management strategies that incorporate surgery and radiotherapy achieve high rates of locoregional control, but distant failure rates remain problematic, highlighting the need for new effective systemic therapies. Chemotherapy can achieve high response rates of limited duration in the metastatic setting, but its role in definitive management remains unproven. Recent developments in our knowledge about the biology of MCC have led to the identification of new potential therapeutic targets and treatments. A key finding has been the discovery that a human polyomavirus may be a causative agent. However, emerging data suggests that MCC may actually be two distinct entities, viral-associated and viral-negative MCC, which is likely to have implications for the management of MCC in the future and for the development of new treatments. In this review, we discuss recent discoveries about the biology of MCC, current approaches to management, and new therapeutic strategies that are being investigated.

Molecular characteristics and potential therapeutic targets in Merkel cell carcinoma

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin tumour occurring preferentially in elderly and immunosuppressed individuals. Multiple studies have provided insight into the molecular alterations of MCC, leading to the design of several ongoing clinical trials testing chemotherapy, targeted therapy and immunotherapy in patients with recurrent or metastatic disease. The results of some of these studies are available, whereas others are eagerly awaited and will likely shed light on the understanding of MCC biology and potentially improve the clinical outcomes of patients with this rare disease.

Tenascin-C: Form versus function

Tenascin-C is a large, multimodular, extracellular matrix glycoprotein that exhibits a very restricted pattern of expression but an enormously diverse range of functions. Here, we discuss the importance of deciphering the expression pattern of, and effects mediated by, different forms of this molecule in order to fully understand tenascin-C biology. We focus on both post transcriptional and post translational events such as splicing, glycosylation, assembly into a 3D matrix and proteolytic cleavage, highlighting how these modifications are key to defining tenascin-C function.

Tenascin-C: Exploitation and collateral damage in cancer management

Despite an increasing knowledge about the causes of cancer, this disease is difficult to cure and still causes far too high a death rate. Based on advances in our understanding of disease pathogenesis, novel treatment concepts, including targeting the tumor microenvironment, have been developed and are being combined with established treatment regimens such as surgical removal and radiotherapy. Yet it is obvious that we need additional strategies to prevent tumor relapse and metastasis. Given its exceptional high expression in most cancers with low abundance in normal tissues, tenascin-C appears an ideal candidate for tumor treatment. Here, we will summarize the current applications of targeting tenascin-C as a treatment for different tumors, and highlight the potential of this therapeutic approach.

Mechanisms of action of therapeutic antibodies for cancer

The therapeutic utility of antibodies and their derivatives is achieved by various means. The FDA has approved several targeted antibodies that disrupt signaling of various growth factor receptors for the treatment of a number of cancers. Rituximab, and other anti-CD20 monoclonal antibodies are active in B cell malignancies. As more experience has been gained with anti-CD20 monoclonal antibodies, the multifactorial nature of their anti-tumor mechanisms has emerged. Other targeted antibodies function to dampen inhibitory checkpoints. These checkpoint inhibitors have recently achieved dramatic results in several cancers, including melanoma. These and related antibodies continue to be investigated in the clinical and pre-clinical settings. Novel antibody structures that target two or more antigens have also made their way into clinical use. Tumor targeted antibodies can also be conjugated to chemo- or radiotherapeutic agents, or catalytic toxins, as a means to deliver toxic payloads to cancer cells. Here we provide a review of these mechanisms and a discussion of their relevance to current and future clinical applications.

Antibody fusions with immunomodulatory proteins for cancer therapy

The potential of immunomodulatory proteins, in particular cytokines, for cancer therapy is well recognized, but hampered by the toxicity associated with their systemic application. In order to address this problem, targeted delivery by antibody fusion proteins has been early proposed and their development intensively pursued over the last decade. Here, factors influencing the selection and modification of cytokines and antibody formats for this approach are being discussed, indicating current developments and translational advances in the field.

The antibody-mediated targeted delivery of interleukin-13 to syngeneic murine tumors mediates a potent anticancer activity

We describe the expression and in vivo characterization of an antibody-cytokine fusion protein, based on murine Interleukin-13 (IL13) and the monoclonal antibody F8, specific to the alternatively spliced extra domain A of fibronectin, a marker of neo-angiogenesis. The IL13 moiety was fused at the C-terminal extremity of the F8 antibody in diabody format. The resulting F8-IL13 immunocytokine retained the full binding properties of the parental antibody and cytokine bioactivity. The fusion protein could be expressed in mammalian cells, purified to homogeneity and showed a preferential accumulation at the tumor site. When used as single agent at doses of 200 μg, F8-IL13 exhibited a strong inhibition of tumor growth rate in two models of cancer (F9 teratocarcinoma and Wehi-164), promoting an infiltration of various types of leukocytes into the neoplastic mass. This anticancer activity could be potentiated by combination with an immunocytokine based on the F8 antibody and murine IL12, leading to complete and long-lasting tumor eradications. Mice cured from Wehi-164 sarcomas acquired a durable protective antitumor immunity, and selective depletion of immune cells revealed that the antitumor activity was mainly mediated by cluster of differentiation 4-positive T cells. This study indicates that IL13 can be efficiently delivered to the tumor neo-vasculature and that it mediates a potent anticancer activity in the two models of cancer investigated in this study. The observed mechanism of action for F8-IL13 was surprising, since immunocytokines based on other payloads (e.g., IL2, IL4, IL12 and TNF) eradicate cancer by the combined contribution of natural killer cells and cluster of differentiation 8-positive T cells.

Interrogation of gossypol therapy in glioblastoma implementing cell line and patient-derived tumour models

BACKGROUND

Glioblastoma (GBM), being a highly vascularised and locally invasive tumour, is an attractive target for anti-angiogenic and anti-invasive therapies. The GBM/endothelial cell response to gossypol/temozolomide (TMZ) treatment was investigated with a particular aim to assess treatment effects on cancer hallmarks.

METHODS

Cell viability, endothelial tube formation and GBM tumour cell invasion were variously assessed following combined treatment in vitro. The U87MG-luc2 subcutaneous xenograft model was used to investigate therapeutic response in vivo. Viable tumour response to treatment was interrogated using immunohistochemistry. Combined treatment protocols were also tested in primary GBM patient-derived cultures.

RESULTS

An endothelial/GBM cell viability inhibitory effect, as well as an anti-angiogenic and anti-invasive response, to combined treatment have been demonstrated in vitro. A significantly greater anti-proliferative (P=0.020, P=0.030), anti-angiogenic (P=0.040, P<0.0001) and pro-apoptotic (P=0.0083, P=0.0149) response was observed when combined treatment was compared with single gossypol/TMZ treatment response, respectively. GBM cell line and patient-specific response to gossypol/TMZ treatment was observed.

CONCLUSIONS

Our results indicate that response to a combined gossypol/TMZ treatment is related to inhibition of tumour-associated angiogenesis, invasion and proliferation and warrants further investigation as a novel targeted GBM treatment strategy.

A chemically defined trifunctional antibody-cytokine-drug conjugate with potent antitumor activity

The combination of immunostimulatory agents with cytotoxic drugs is emerging as a promising approach for potentially curative tumor therapy, but advances in this field are hindered by the requirement of testing individual combination partners as single agents in dedicated clinical studies, often with suboptimal efficacy. Here, we describe for the first time a novel multipayload class of targeted drugs, the immunocytokine-drug conjugates (IDC), which combine a tumor-homing antibody, a cytotoxic drug, and a proinflammatory cytokine in the same molecular entity. In particular, the IL2 cytokine and the disulfide-linked maytansinoid DM1 microtubular inhibitor could be coupled to the F8 antibody, directed against the alternatively spliced EDA domain of fibronectin, in a site-specific manner, yielding a chemically defined product with selective tumor-homing performance and potent anticancer activity in vivo, as tested in two different immunocompetent mouse models.

Preclinical evaluation of IL2-based immunocytokines supports their use in combination with dacarbazine, paclitaxel and TNF-based immunotherapy

Antibody-cytokine fusion proteins ("immunocytokines") represent a promising class of armed antibody products, which allow the selective delivery of potent pro-inflammatory payloads at the tumor site. The antibody-based selective delivery of interleukin-2 (IL2) is particularly attractive for the treatment of metastatic melanoma, an indication for which this cytokine received marketing approval from the US Food and drug administration. We used the K1735M2 immunocompetent syngeneic model of murine melanoma to study the therapeutic activity of F8-IL2, an immunocytokine based on the F8 antibody in diabody format, fused to human IL2. F8-IL2 was shown to selectively localize at the tumor site in vivo, following intravenous administration, and to mediate tumor growth retardation, which was potentiated by the combination with paclitaxel or dacarbazine. Combination treatment led to a substantially more effective tumor growth inhibition, compared to the cytotoxic drugs used as single agents, without additional toxicity. Analysis of the immune infiltrate revealed a significant accumulation of CD4(+) T cells 24 h after the administration of the combination. The fusion proteins F8-IL2 and L19-IL2, specific to the alternatively spliced extra domain A and extra domain B of fibronectin respectively, were also studied in combination with tumor necrosis factor (TNF)-based immunocytokines. The combination treatment was superior to the action of the individual immunocytokines and was able to eradicate neoplastic lesions after a single intratumoral injection, a procedure that is being clinically used for the treatment of Stage IIIC melanoma. Collectively, these data reinforce the rationale for the use of IL2-based immunocytokines in combination with cytotoxic agents or TNF-based immunotherapy for the treatment of melanoma patients.

Antibody-cytokine fusion proteins for treatment of cancer: engineering cytokines for improved efficacy and safety

The true potential of cytokine therapies in cancer treatment is limited by the inability to deliver optimal concentrations into tumor sites due to dose-limiting systemic toxicities. To maximize the efficacy of cytokine therapy, recombinant antibody-cytokine fusion proteins have been constructed by a number of groups to harness the tumor-targeting ability of monoclonal antibodies. The aim is to guide cytokines specifically to tumor sites where they might stimulate more optimal anti-tumor immune responses while avoiding the systemic toxicities of free cytokine therapy. Antibody-cytokine fusion proteins containing interleukin (IL)-2, IL-12, IL-21, tumor necrosis factor (TNF)α, and interferons (IFNs) α, β, and γ have been constructed and have shown anti-tumor activity in preclinical and early-phase clinical studies. Future priorities for development of this technology include optimization of tumor targeting, bioactivity of the fused cytokine, and choice of appropriate agents for combination therapies. This review is intended to serve as a framework for engineering an ideal antibody-cytokine fusion protein, focusing on previously developed constructs and their clinical trial results.

A highly functional synthetic phage display library containing over 40 billion human antibody clones

Several synthetic antibody phage display libraries have been created and used for the isolation of human monoclonal antibodies. The performance of antibody libraries, which is usually measured in terms of their ability to yield high-affinity binding specificities against target proteins of interest, depends both on technical aspects (such as library size and quality of cloning) and on design features (which influence the percentage of functional clones in the library and their ability to be used for practical applications). Here, we describe the design, construction and characterization of a combinatorial phage display library, comprising over 40 billion human antibody clones in single-chain fragment variable (scFv) format. The library was designed with the aim to obtain highly stable antibody clones, which can be affinity-purified on protein A supports, even when used in scFv format. The library was found to be highly functional, as >90% of randomly selected clones expressed the corresponding antibody. When selected against more than 15 antigens from various sources, the library always yielded specific and potent binders, at a higher frequency compared to previous antibody libraries. To demonstrate library performance in practical biomedical research projects, we isolated the human antibody G5, which reacts both against human and murine forms of the alternatively spliced BCD segment of tenascin-C, an extracellular matrix component frequently over-expressed in cancer and in chronic inflammation. The new library represents a useful source of binding specificities, both for academic research and for the development of antibody-based therapeutics.

Prognostic value of the preoperative immunological profile in patients with glioblastoma

Background:

Aim of our study was to determine the predictive impact of certain serum immunological markers on overall survival (OS) in patients with glioblastoma multiforme (GBM).

Methods:

We assayed prospectively values of interleukin 2 (IL-2), immunoglobulin G (IgG), C4, CD3+, CD4+ and CD8+ cells via flow cytometry, enzyme-linked immunosorbent assay (ELISA) and radial immunodiffusion in preoperative sera of adult patients with de novo histologically confirmed supratentorial GBM. Kaplan-Meier method and Cox proportional hazards models were used to assess clinical, laboratory, and treatment prognostic factors for OS.

Results:

Twenty-six consecutive patients were identified with a mean age of 59.6 years. Median follow up was 12 months. Lower IL-2 values (<7.97 pg/ml vs. ≥7.97 pg/ml, P = 0.029) und CD4+ counts (<200 cells/μl vs. ≥200 cells/μl, P < 0.001) correlated significantly with a shorter OS. The independent prognostic relevance of CD4 + counts was confirmed by the multivariate analysis (HR = 0.010, 95% CI 0.001-0.226, P = 0.011). Further independent prognostic factors for OS were type of resection (resection vs. biopsy) and administration of radiotherapy (yes/no).

Conclusion:

Preoperative values IL-2 and CD4+ cells in sera may carry a prognostic impact. Novel diagnostic models prior to histopathological confirmation may be used to predict prognosis of patients with GBM. Future studies should investigate whether targeting immune factors, such as CD4+ and IL-2, may improve the prognosis of patients with GBM.

Systemic Therapy for Merkel Cell Carcinoma: What's on the Horizon?

Merkel cell carcinoma is an aggressive neuroendocrine skin cancer that usually affects elderly patients. Despite being uncommon, incidence has been steadily increasing over the last two decades, likely due to increased awareness, better diagnostic methods and aging of the population. It is currently one of the most lethal cutaneous malignancies, with a five-year overall survival of approximately 50%. With the better understanding of the molecular pathways that lead to the development of Merkel cell carcinoma, there has been an increasing excitement and optimism surrounding novel targeted therapies, in particular to immunotherapy. Some of the concepts surrounding the novel targeted therapies and currently ongoing clinical trials are reviewed here.

Antibody-based delivery of interleukin-2 to neovasculature has potent activity against acute myeloid leukemia

Acute myeloid leukemia (AML) is a rapidly progressing disease that is accompanied by a strong increase in microvessel density in the bone marrow. This observation prompted us to stain biopsies of AML and acute lymphoid leukemia (ALL) patients with the clinical-stage human monoclonal antibodies F8, L19, and F16 directed against markers of tumor angiogenesis. The analysis revealed that the F8 and F16 antibodies strongly stained 70% of AML and 75% of ALL bone marrow specimens, whereas chloroma biopsies were stained with all three antibodies. Therapy experiments performed in immunocompromised mice bearing human NB4 leukemia with the immunocytokine F8-IL2 [consisting of the F8 antibody fused to human interleukin-2 (IL-2)] mediated a strong inhibition of AML progression. This effect was potentiated by the addition of cytarabine, promoting complete responses in 40% of treated animals. Experiments performed in immunocompetent mice bearing C1498 murine leukemia revealed long-lasting complete tumor eradication in all treated mice. The therapeutic effect of F8-IL2 was mediated by both natural killer cells and CD8(+) T cells, whereas CD4(+) T cells appeared to be dispensable, as determined in immunodepletion experiments. The treatment of an AML patient with disseminated extramedullary AML manifestations with F16-IL2 (consisting of the F16 antibody fused to human IL-2, currently being tested in phase 2 clinical trials in patients with solid tumors) and low-dose cytarabine showed significant reduction of AML lesions and underlines the translational potential of vascular tumor-targeting antibody-cytokine fusions for the treatment of patients with leukemia.

Immunocytokines: a review of molecules in clinical development for cancer therapy

The concept of therapeutically enhancing the immune system’s responsiveness to tumors is long standing. Several cytokines have been investigated in clinical trials for their therapeutic activity in cancer patients. However, substantial side effects and unfavorable pharmacokinetic properties have been a major drawback hampering the administration of therapeutically relevant doses. The use of recombinant antibody–cytokine fusion proteins promises to significantly enhance the therapeutic index of cytokines by targeting them to the site of disease. This review aims to provide a concise and complete overview of the preclinical data and clinical results currently available for all immunocytokines having reached clinical development.

The antibody-based targeted delivery of interleukin-4 and 12 to the tumor neovasculature eradicates tumors in three mouse models of cancer

Preclinical studies with recombinant murine interleukin 4 (IL4) in models of cancer have shown potent tumor growth inhibition. However, systemic administration of human IL4 to cancer patients exhibited modest antitumor activity and considerable toxicities. To improve the therapeutic index and reduce side effects of this cytokine, we developed of a novel "immunocytokine" based on sequential fusion of murine IL4 with the antibody fragment F8 (specific to the alternatively spliced extra-domain A of fibronectin, a marker for tumor-angiogenesis) in diabody format. The resulting fusion protein, termed F8-IL4, retained full antigen-binding activity and cytokine bioactivity and was able to selectively localize on solid tumors in vivo. When used as single agent, F8-IL4 inhibited tumor growth in three different immunocompetent murine cancer models (F9 teratocarcinoma, CT26 colon carcinoma and A20 lymphoma). Furthermore, F8-IL4 showed synergistic effects when coadministered with immunocytokines based on IL2 and IL12. Indeed, combination therapy with an IL12-based immunocytokine yielded complete tumor eradication, in spite of the fact that IL4 and IL12 display opposite immunological mechanisms of action in terms of their polarization of T-cell based responses. No weight loss or any signs of toxicity were observed in treated mice, both in monotherapy and in combination, indicating a good tolerability of the immunocytokine treatment. Interestingly, mice cured from CT26 tumors acquired a durable protective antitumor immunity. Depletion experiments indicated that the antitumor activity was mediated by CD8+ T cells and by NK cells.

Balancing risks and benefits of anti-angiogenic drugs for malignant glioma

Angiogenesis is a delicate process that has been programmed over the time of evolution of vertebrates to provide optimized quantities of oxygen and nutrients to the developing embryo and the growing newborn. Similarly, angiogenesis induction pathways are used during tumor development. Angiogenesis and tumor cell invasion are closely linked. Anti-angiogenesis treatment strategies have entered the clinic and show some promising results. However, recent research using preclinical models have pointed to possible harmful effects, including evasive resistance and increase in tumor cell invasion when VEGF activity is inhibited. This has been corroborated by observations in treated glioblastoma patients. However, the meaning of these observations is still in question. The results of Phase III clinical trials that are ongoing will certainly provide more definitive answers with regard to evasive resistance in glioblastoma treated with anti-angiogenic drugs.

Immunocytokines: a novel class of potent armed antibodies

Several cytokines have been investigated in clinical trials, based on their potent therapeutic activity observed in animal models of cancer and other diseases. However, substantial toxicities are often reported at low doses, thus preventing escalation to therapeutically active regimens. The use of recombinant antibodies or antibody fragments as delivery vehicles promises to enhance greatly the therapeutic index of pro-inflammatory and anti-inflammatory cytokines. This review surveys preclinical and clinical data published in the field of antibody-cytokine fusions (immunocytokines). Molecular determinants (such as molecular format, valence, target antigen), which crucially contribute to immunocytokine performance in vivo, are discussed in the article, as well as recent trends for the combined use of this novel class of biopharmaceuticals with other therapeutic agents.

Emphasising the European Union's Commitment to Cancer Research: a helicopter view of the Seventh Framework Programme for Research and Technological Development

This article discusses the efforts undertaken in the European Union toward basic, translational, and clinical cancer research on prevention, early diagnosis, prognosis, treatment, cancer control, quality of life, and survivorship.

Challenges in immunotherapy presented by the glioblastoma multiforme microenvironment

Glioblastoma multiforme (GBM) is the most common and aggressive primary brain tumor in adults. Despite intensive treatment, the prognosis for patients with GBM remains grim with a median survival of only 14.6 months. Immunotherapy has emerged as a promising approach for treating many cancers and affords the advantages of cellular-level specificity and the potential to generate durable immune surveillance. The complexity of the tumor microenvironment poses a significant challenge to the development of immunotherapy for GBM, as multiple signaling pathways, cytokines, and cell types are intricately coordinated to generate an immunosuppressive milieu. The development of new immunotherapy approaches frequently uncovers new mechanisms of tumor-mediated immunosuppression. In this review, we discuss many of the current approaches to immunotherapy and focus on the challenges presented by the tumor microenvironment.

Differential vascular expression and regulation of oncofetal tenascin-C and fibronectin variants in renal cell carcinoma (RCC): implications for an individualized angiogenesis-related targeted drug delivery

The study was aimed at determining the vascular expression of oncofetal fibronectin (oncfFn) and tenascin-C (oncfTn-C) isoforms in renal cell carcinoma (RCC) and its metastases which are well-known targets for antibody-based pharmacodelivery. Furthermore, the influence of tumour cells on endothelial mRNA expression of these molecules was investigated. Evaluation of vascular ED-A(+) and ED-B(+) Fn as well as A1(+) and C(+) Tn-C was performed after immunofluorescence double and triple staining using human recombinant antibodies on clear cell, papillary and chromophobe primary RCC and metastases. The influence of hypoxic RCC-conditioned medium on oncfFn and oncfTn-C mRNA expression was examined in human umbilical vein endothelial cells (HUVEC) by real time RT-PCR. There are RCC subtype specific expression profiles of vascular oncfFn and oncfTn-C and corresponding patterns when comparing primary tumours and metastases. Within one tumour, there are different vessel populations with regard to the incorporation of oncfTn-C and oncfFn into the vessel wall. In vitro tumour-derived soluble mediators induce an up regulation of oncfTn-C and oncfFn mRNA in HUVEC which can be blocked by Avastin(®). Vascular expression of oncFn and oncTn-C variants depends on RCC subtype and may reflect an individual tumour stroma interaction or different stages of vessel development. Therefore, oncFn or oncTn-C variants can be suggested as molecular targets for individualized antibody based therapy strategies in RCC. Tumour-derived VEGF could be shown to regulate target expression.

Understanding the role of cytokines in Glioblastoma Multiforme pathogenesis

Cytokines play a significant role in cancer diagnosis, prognosis and therapy. The immune system's failure to recognize the malignant tumor cells and mount an effective response may be the result of tumor-associated cytokine deregulation. Glioblastoma Multiforme (GBM) has a characteristic cytokine expression pattern, and abnormalities in cytokine expression have been implicated in gliomagenesis. Within the heterogeneous GBM microenvironment, the tumor cells, normal brain cells, immune cells, and stem cells interact with each other through the complex cytokine network. This review summarizes the current understanding of the functions of key cytokines on GBM, and highlights potential therapeutic applications targeting these cytokines.

The targeted delivery of IL17 to the mouse tumor neo-vasculature enhances angiogenesis but does not reduce tumor growth rate

There has been a long controversy as to whether interleukin-17 (IL17) has an impact on tumor growth. In order to assess whether IL17 may affect tumor growth, it would be convenient to achieve high levels of this pro-inflammatory cytokine at the tumor neo-vasculature, since IL17 is known to promote angiogenesis. Here, we have generated and tested in vivo a fusion protein, consisting of the F8 antibody (specific to the alternatively spliced EDA domain of fibronectin, a marker of angiogenesis) and of murine IL17 (mIL17). The resulting immunocytokine (termed F8-mIL17) was shown to selectively localize at the tumor neo-vasculature and to vigorously promote tumor angiogenesis, without however reducing or enhancing tumor growth rate both in immunocompetent and in immunodeficient mice.

Advances in tenascin-C biology

Tenascin-C is an extracellular matrix glycoprotein that is specifically and transiently expressed upon tissue injury. Upon tissue damage, tenascin-C plays a multitude of different roles that mediate both inflammatory and fibrotic processes to enable effective tissue repair. In the last decade, emerging evidence has demonstrated a vital role for tenascin-C in cardiac and arterial injury, tumor angiogenesis and metastasis, as well as in modulating stem cell behavior. Here we highlight the molecular mechanisms by which tenascin-C mediates these effects and discuss the implications of mis-regulated tenascin-C expression in driving disease pathology.

The antibody-mediated targeted delivery of interleukin-10 inhibits endometriosis in a syngeneic mouse model

BACKGROUND

Endometriosis is still a highly underdiagnosed disease, and the current medical and surgical treatment of endometriosis is associated with a high recurrence rate. This study investigates the use of derivatives of the human antibody F8, specific to the alternatively spliced extra-domain A of fibronectin (Fn), for the imaging and treatment of endometriosis.

METHODS

Immunohistochemistry and immunofluorescence was used to evaluate antigen expression in endometriotic tissue of human endometriosis and of a syngeneic mouse model of the disease. The in vivo targeting performance of a fluorescent derivative of the F8 antibody was assessed by imaging mice with endometriosis using a near-infrared fluorescence imager, 24 h following i.v. injection of the antibody conjugate. Furthermore, the mouse model was used for therapy experiments using two recombinant F8-based immunocytokines [F8-interleukin-10 (IL10) and F8-IL2] or saline for the treatment groups.

RESULTS

A very strong vascular expression of splice isoforms of Fn and of tenascin-C was observed in human endometriotic lesions by immunohistochemistry and immunofluorescence techniques. After i.v. administration, a selective accumulation of the F8 antibody in endometriotic lesions could be observed in a syngeneic mouse model. These targeting data were used as a basis for therapy experiments with a pro-inflammatory (F8-IL2) and an anti-inflammatory (F8-IL10) cytokine fusion protein of the F8 antibody. The average lesion size in the F8-IL10 treatment group was clearly reduced compared with the saline control group and with the F8-IL2 group, for which no therapeutic effects were observed.

CONCLUSIONS

The F8 antibody targets endometriotic lesions in vivo in a mouse model of endometriosis and may be used for the non-invasive imaging of the disease and for the pharmacodelivery of anti-inflammatory cytokines, such as IL10.

Cloning and characterization of novel tumor-targeting immunocytokines based on murine IL7

We generated and characterized novel antibody-cytokine fusion proteins ("immunocytokines") based on murine interleukin-7 (IL7), an immunomodulatory protein which has previously shown anti-cancer activity in preclinical models and whose human counterpart is currently being investigated in clinical trials. The sequential fusion of the clinical-stage antibody fragment scFv(F8), specific to a tumor-associated splice isoform of fibronectin, yielded an immunocytokine (termed "F8-mIL7") of insufficient pharmaceutical quality and in vivo tumor targeting performance, with a striking dose dependence on tumor targeting selectivity. By contrast, a novel immunocytokine design (termed "F8-mIL7-F8"), in which two scFv moieties were fused at the N- and C-terminus of murine IL7, yielded a protein of excellent pharmaceutical quality and with improved tumor-targeting performance [tumor: blood ratio=16:1, 24h after injection]. Both F8-mIL7 and F8-mIL7-F8 could induce tumor growth retardation in immunocompetent mice, but were not able to eradicate F9 tumors. The combination of F8-mIL7-F8 with paclitaxel led to improved therapeutic results, which were significantly better compared to those obtained with saline treatment. The study indicates how the engineering of novel immunocytokine formats may help generate fusion proteins of acceptable pharmaceutical quality, for those immunomodulatory proteins which do not lend themselves to a direct fusion with antibody fragments.