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

Protein isoform-centric therapeutics: expanding targets and increasing specificity

Most protein-coding genes produce multiple protein isoforms; however, these isoforms are commonly neglected in drug discovery. The expression of protein isoforms can be specific to a disease, tissue and/or developmental stage, and this specific expression can be harnessed to achieve greater drug specificity than pan-targeting of all gene products and to enable improved treatments for diseases caused by aberrant protein isoform production. In recent years, several protein isoform-centric therapeutics have been developed. Here, we collate these studies and clinical trials to highlight three distinct but overlapping modes of action for protein isoform-centric drugs: isoform switching, isoform introduction or depletion, and modulation of isoform activity. In addition, we discuss how protein isoforms can be used clinically as targets for cell type-specific drug delivery and immunotherapy, diagnostic biomarkers and sources of cancer neoantigens. Collectively, we emphasize the value of a focus on isoforms as a route to discovering drugs with greater specificity and fewer adverse effects. This approach could enable the targeting of proteins for which pan-inhibition of all isoforms is toxic and poorly tolerated.

Relaxed fibronectin: a potential novel target for imaging endometriotic lesions

BACKGROUND

Endometriosis is characterized by the ectopic occurrence of endometrial tissue. Though considered benign, endometriotic lesions possess tumor-like properties such as tissue invasion and remodeling of the extracellular matrix. One major clinical hurdle concerning endometriosis is its diagnosis. The diagnostic modalities ultrasound and MRI are often unable to detect all lesions, and a clear correlation between imaging and clinical symptoms is still controversial. Therefore, it was our aim to identify a potential target to image active endometriotic lesions.

RESULTS

For our studies, we employed the preclinical radiotracer [111In]In-FnBPA5, which specifically binds to relaxed fibronectin-an extracellular matrix protein with key functions in homeostasis that has been implicated in the pathogenesis of diseases such as cancer and fibrosis. We employed this tracer in biodistribution as well as SPECT/CT studies in mice and conducted immunohistochemical stainings on mouse uterine tissue as well as on patient-derived endometriosis tissue. In biodistribution and SPECT/CT studies using the radiotracer [111In]In-FnBPA5, we found that radiotracer uptake in the myometrium varies with the estrous cycle of the mouse, leading to higher uptake of [111In]In-FnBPA5 during estrogen-dependent phases, which indicates an increased abundance of relaxed fibronectin when estrogen levels are high. Finally, immunohistochemical analysis of patient samples demonstrated that there is preferential relaxation of fibronectin in the proximity of the endometriotic stroma.

CONCLUSION

Estrous cycle stages characterized by high estrogen levels result in a higher abundance of relaxed fibronectin in the murine myometrium. This finding together with a first proof-of-concept study employing human endometriosis tissues suggests that relaxed fibronectin could be a potential target for the development of a diagnostic radiotracer targeting endometriotic lesions. With [111In]In-FnBPA5, the matching targeting molecule is in preclinical development.

Imaging of Endometriotic Lesions Using cRGD-MN Probe in a Mouse Model of Endometriosis

Approximately 10% of women suffer from endometriosis during their reproductive years. This disease is a chronic debilitating condition whose etiology for lesion implantation and survival heavily relies on adhesion and angiogenic factors. Currently, there are no clinically approved agents for its detection. In this study, we evaluated cRGD-peptide-conjugated nanoparticles (RGD-Cy5.5-MN) to detect lesions using magnetic resonance imaging (MRI) in a mouse model of endometriosis. We utilized a luciferase-expressing murine suture model of endometriosis. Imaging was performed before and after 24 h following the intravenous injection of RGD-Cy5.5-MN or control nanoparticles (Cy5.5-MN). Next, we performed biodistribution of RGD-Cy5.5-MN and correlative fluorescence microscopy of lesions stained for CD34. Tissue iron content was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). Our results demonstrated that targeting endometriotic lesions with RGD-Cy5.5-MN resulted in a significantly higher delta T2* upon its accumulation compared to Cy5.5-MN. ICP-OES showed significantly higher iron content in the lesions of the animals in the experimental group compared to the lesions of the animals in the control group. Histology showed colocalization of Cy5.5 signal from RGD-Cy5.5-MN with CD34 in the lesions pointing to the targeted nature of the probe. This work offers initial proof-of-concept for targeting angiogenesis in endometriosis which can be useful for potential clinical diagnostic and therapeutic approaches for treating this disease.

IL-10 is not anti-fibrotic but pro-fibrotic in endometriosis: IL-10 treatment of endometriotic stromal cells in vitro promotes myofibroblast proliferation and collagen type I protein expression

STUDY QUESTION

Is interleukin-10 (IL-10) anti-fibrotic in endometriosis?

SUMMARY ANSWER

IL-10 is not anti-fibrotic but pro-fibrotic in endometriosis, because IL-10 treatment of endometriotic stromal cells in vitro promotes myofibroblast proliferation and collagen type I protein expression.

WHAT IS KNOWN ALREADY

We previously showed that persistent activation of signal transducer and activator of transcription 3 (STAT3) via IL-6 trans-signaling promotes fibrosis of endometriosis. Studies showed marked anti-fibrotic effects of IL-10 via the STAT3 signaling pathway, which is generally considered to be anti-inflammatory, in various organs.

STUDY DESIGN, SIZE, DURATION

Endometrial and/or endometriotic samples of 54 patients who had histological evidence of deep endometriosis, and endometrial samples from 30 healthy fertile women were analyzed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The effects of IL-10/STAT3 signaling as well as inhibition of STAT3 activation by knockdown of STAT3 gene on the pro-fibrotic phenotype in endometrial and endometriotic stromal cells in vitro were investigated. Then, the effects of various time points of IL-10 treatment in combination with transforming growth factor (TGF)-β1 and/or IL-6/soluble IL-6 receptor (sIL-6R) on the profibrotic phenotype of endometrial and endometriotic stromal cells were investigated.

MAIN RESULTS AND THE ROLE OF CHANCE

IL-10 induced pro-fibrotic phenotype (cell proliferation, collagen type I synthesis, α-smooth muscle actin positive stress fibers and collagen gel contraction) of endometriotic stromal cells. Knockdown of STAT3 gene decreased the IL-10 induced pro-fibrotic phenotype of endometriotic stromal cells. In contrast, IL-10 had no significant effects on pro-fibrotic phenotype of endometrial stromal cells of healthy women. Sequential IL-10 treatment with or without TGF-β1 and/or IL-6/sIL-6R induced persistent activation of STAT3 and significantly increased proliferation of myofibroblasts (cells with α-smooth muscle actin positive stress fibers) and protein expression of collagen type I in endometriotic stromal cells. TGF-β1 and/or IL-6/sIL6RIL-6/sIL6R treatment significantly increased tissue inhibitor of metalloproteinase 1 (TIMP1) protein expression, whereas IL-10 had no significant effects. Knockdown of STAT3 gene significantly decreased the TGF-β1 and/or IL-6/sIL6R induced TIMP1 protein expression. In contrast, pre-treatment with IL-10 before TGF-β1 and/or IL-6/sIL-6R treatment and sequential IL-10 treatment with or without TGF-β1 and/or IL-6/sIL-6R significantly decreased proliferation of fibroblasts (cells without α-smooth muscle actin positive stress fibers) and collagen type I protein expression in endometrial stromal cells of healthy women.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Given the large number of complex interactions and signaling pathways of pro- and anti-inflammatory mediators that are involved in the pathophysiology of endometriosis, the present study investigated only a very small portion of the whole. Further in vivo studies are required to validate the present findings.

WIDER IMPLICATIONS OF THE FINDINGS

Inflammatory mediators in the pathophysiology of endometriosis have been extensively investigated as potential therapeutic targets. However, the present study showed that anti-inflammatory signals of IL-10 and IL-6 through persistent STAT3 activation may promote endometriosis fibrosis. Therapeutic strategies, such as suppression of 'inflammation', might dysregulate the cross-regulation of 'pro- and anti-inflammatory mediators', leading to detrimental effects in patients with endometriosis, such as fibrosis. To develop new, but not deleterious, therapeutic strategies, studies are required to investigate whether, how and what 'anti-inflammatory mediators' along with pro-inflammatory mediators are involved in individual patients with endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported in part by KARL STORZ SE & Co. KG (Tuttlingen, Germany). The authors have no conflict of interest to disclose.

Homing Peptide-Based Targeting of Tenascin-C and Fibronectin in Endometriosis

The current diagnostic and therapeutic strategies for endometriosis are limited. Although endometriosis is a benign condition, some of its traits, such as increased cell invasion, migration, tissue inflammation, and angiogenesis are similar to cancer. Here we explored the application of homing peptides for precision delivery of diagnostic and therapeutic compounds to endometriotic lesions. First, we audited a panel of peptide phages for the binding to the cultured immortalized endometriotic epithelial 12Z and eutopic stromal HESC cell lines. The bacteriophages displaying PL1 peptide that engages with angiogenic extracellular matrix overexpressed in solid tumors showed the strongest binding to both cell lines. The receptors of PL1 peptide, tenascin C domain C (TNC-C) and fibronectin Extra Domain-B (Fn-EDB), were expressed in both cells. Silver nanoparticles functionalized with synthetic PL1 peptide showed specific internalization in 12Z and HESC cells. Treatment with PL1-nanoparticles loaded with the potent antimitotic drug monomethyl auristatin E decreased the viability of endometriotic cells in 2D and 3D cultures. Finally, PL1-nanoparticless bound to the cryosections of clinical peritoneal endometriotic lesions in the areas positive for TNC-C and Fn-EDB immunoreactivities and not to sections of normal endometrium. Our findings suggest potential applications for PL1-guided nanoparticles in precision diagnosis and therapy of endometriosis.

Drug delivery strategies for management of women's health issues in the upper genital tract

The female upper genital tract (UGT) hosts important reproductive organs including the cervix, uterus, fallopian tubes, and ovaries. Several pathologies affect these organ systems such as infections, reproductive issues, structural abnormalities, cancer, and inflammatory diseases that could have significant impact on women's overall health. Effective disease management is constrained by the multifaceted nature of the UGT, complex anatomy and a dynamic physiological environment. Development of drug delivery strategies that can overcome mucosal and safety barriers are needed for effective disease management. This review introduces the anatomy, physiology, and mucosal properties of the UGT and describes drug delivery barriers, advances in drug delivery technologies, and opportunities available for new technologies that target the UGT.

Therapeutic Evaluation of Antibody-Based Targeted Delivery of Interleukin 9 in Experimental Pulmonary Hypertension

Background and Aims: Pulmonary hypertension (PH) is a heterogeneous disorder associated with poor prognosis. For the majority of patients, only limited therapeutic options are available. Thus, there is great interest to develop novel treatment strategies focusing on pulmonary vascular and right ventricular remodeling. Interleukin 9 (IL9) is a pleiotropic cytokine with pro- and anti-inflammatory functions. The aim of this study was to evaluate the therapeutic activity of F8IL9F8 consisting of IL9 fused to the F8 antibody, specific to the alternatively-spliced EDA domain of fibronectin, which is abundantly expressed in pulmonary vasculature and right ventricular myocardium in PH. Methods: The efficacy of F8IL9F8 in attenuating PH progression in the monocrotaline mouse model was evaluated in comparison to an endothelin receptor antagonist (ERA) or an IL9 based immunocytokine with irrelevant antibody specificity (KSFIL9KSF). Treatment effects were assessed by right heart catheterization, echocardiography as well as histological and immunohistochemical tissue analyses. Results: Compared to controls, systolic right ventricular pressure (RVPsys) was significantly elevated and a variety of right ventricular echocardiographic parameters were significantly impaired in all MCT-induced PH groups except for the F8IL9F8 group. Both, F8IL9F8 and ERA treatments lead to a significant reduction in RVPsys and an improvement of echocardiographic parameters when compared to the MCT group not observable for the KSFIL9KSF group. Only F8IL9F8 significantly reduced lung tissue damage and displayed a significant decrease of leukocyte and macrophage accumulation in the lungs and right ventricles. Conclusions: Our study provides first pre-clinical evidence for the use of F8IL9F8 as a new therapeutic agent for PH in terms of a disease-modifying concept addressing cardiovascular remodeling.

Antibody-based delivery of interleukin-9 to neovascular structures: Therapeutic evaluation in cancer and arthritis

Interleukin-9 is a cytokine with multiple functions, including the ability to activate group 2 innate lymphoid cells, which has been postulated to be therapeutically active in mouse models of arthritis. Similarly, interleukin-9 has been suggested to play an important role in tumor immunity. Here, we describe the cloning, expression, and characterization of three fusion proteins based on murine interleukin-9 and the F8 antibody, specific to the alternatively spliced EDA domain of fibronectin. EDA is strongly expressed in cancer and in various arthritic conditions, while being undetectable in the majority of healthy organs. Interleukin-9-based fusion proteins with an irrelevant antibody specific to hen egg lysozyme served as negative control in our study. The fusion proteins were characterized by quantitative biodistribution analysis in tumor-bearing mice using radioiodinated protein preparations. The highest tumor uptake and best tumor:organ ratios were observed for a format, in which the interleukin-9 moiety was flanked by two units of the F8 antibody in single-chain Fv format. Biological activity of interleukin-9 was retained when the payload was fused to antibodies. However, the targeted delivery of interleukin-9 to the disease site resulted in a modest anti-tumor activity in three different murine models of cancer (K1735M2, CT26, and F9), while no therapeutic benefit was observed in a collagen induced model of arthritis. Collectively, these results confirm the possibility to deliver interleukin-9 to the site of disease but cast doubts about the alleged therapeutic activity of this cytokine in cancer and arthritis, which has been postulated in previous publications.

A novel progress of drug delivery system for organelle targeting in tumour cells

At present, malignant tumours have become one of the most serious diseases that endanger human health. According to a survey on causes of death in Chinese population in early 1990s, the malignant tumours were the second leading cause of death. In the treatment of tumours, the ideal situation is that drugs should target and accumulate at tumour sites and destroy tumour cells specifically, without affecting normal cells and stem cells with regenerative capacity. This requires drugs to be specifically transported to the target organs, tissues, cells, and even specific organelles, like mitochondria, nuclei, lysosomes, endoplasmic reticulum (ER), and Golgi apparatus (GA). The nano drug delivery system can not only protect drugs from degradation but also facilitate functional modification and targeted drug delivery to the tumour site. This article mainly reviews the targeting of nano drug delivery systems to tumour cytoplasmic matrix, nucleus, mitochondria, ER, and lysosomes. Organelle-specific drug delivery system will be a major mean of targeting drug delivery with lower toxicity, less dosage and higher drug concentration in tumour cells.

Endometriotic inflammatory microenvironment induced by macrophages can be targeted by niclosamide†

Endometriosis causes severe chronic pelvic pain and infertility. We have recently reported that niclosamide treatment reduces growth and progression of endometriosis-like lesions and inflammatory signaling (NF${\rm \small K}$B and STAT3) in a mouse model. In the present study, we examined further inhibitory mechanisms by which niclosamide affects endometriotic lesions using an endometriotic epithelial cell line, 12Z, and macrophages differentiated from a monocytic THP-1 cell line. Niclosamide dose dependently reduced 12Z viability, reduced STAT3 and NF${\rm \small K}$B activity, and increased both cleaved caspase-3 and cleaved PARP. To model the inflammatory microenvironment in endometriotic lesions, we exposed 12Z cells to macrophage conditioned media (CM). Macrophages were differentiated from THP-1 cells using 12-O-tetradecanoylphorbol-13-acetate as M0, and then M0 macrophages were polarized into M1 or M2 using LPS/IFNγ or IL4/IL13, respectively. Conditioned media from M0, M1, or M2 cultures increased 12Z viability. This effect was blocked by niclosamide, and cell viability returned to that of CM from cells treated with niclosamide alone. To assess proteins targeted by niclosamide in 12Z cells, CM from 12Z cells cultured with M0, M1, or M2 with/without niclosamide were analyzed by cytokine/chemokine protein array kits. Conditioned media from M0, M1, and/or M2 stimulated the secretion of cytokines/chemokines from 12Z cells. Production of most of these secreted cytokines/chemokines in 12Z cells was inhibited by niclosamide. Knockdown of each gene in 12Z cells using siRNA resulted in reduced cell viability. These results indicate that niclosamide can inhibit the inflammatory factors in endometriotic epithelial cells stimulated by macrophages by targeting STAT3 and/or NF${\rm \small K}$B signaling.

Advances in antibody engineering for rheumatic diseases

The advent of biologic therapies, particularly antibody therapeutics, has revolutionized the pharmacological treatment of many rheumatic diseases. Antibody discovery began with the immunization of mice for the production of rodent immunoglobulins, but advances in protein and genetic engineering have now made it possible to generate fully human antibodies, which are better tolerated by patients. For most clinical applications in rheumatology, antibodies have been used as blocking agents capable of neutralizing the function of pro-inflammatory proteins, such as TNF. The latest strategies involve antibody products armed with effector moieties, such as anti-inflammatory drugs or cytokines, or antibody products that are specific for multiple targets for the selective inhibition of inflammation at sites of disease. Antibodies are some of the best-selling drugs in the world, and with further advances in antibody development, engineering of armed antibodies and bispecific products will have an important role in the treatment of rheumatic diseases.

B lymphocytes inactivation by Ibrutinib limits endometriosis progression in mice

STUDY QUESTION

What are the effects of B lymphocyte inactivation or depletion on the progression of endometriosis?

SUMMARY ANSWER

Skewing activated B cells toward regulatory B cells (Bregs) by Bruton’s tyrosine kinase (Btk) inhibition using Ibrutinib prevents endometriosis progression in mice while B cell depletion using an anti-CD20 antibody has no effect.

WHAT IS KNOWN ALREADY

A polyclonal activation of B cells and the presence of anti-endometrial autoantibodies have been described in a large proportion of women with endometriosis though their exact role in the disease mechanisms remains unclear.

STUDY DESIGN, SIZE, DURATION

This study included comparison of endometriosis progression for 21 days in control mice versus animals treated with the anti-CD20 depleting antibody or with the Btk inhibitor Ibrutinib that prevents B cell activation.

PARTICIPANTS/MATERIALS, SETTING, METHODS

After syngeneic endometrial transplantation, murine endometriotic lesions were compared between treated and control mice using volume, weight, ultrasonography, histology and target genes expression in lesions. Phenotyping of activated and regulatory B cells, T lymphocytes and macrophages was performed by flow cytometry on isolated spleen and peritoneal cells. Cytokines were assayed by ELISA.

MAIN RESULTS AND THE ROLE OF CHANCE

Btk inhibitor Ibrutinib prevented lesion growth, reduced mRNA expression of cyclooxygenase-2, alpha smooth muscle actin and type I collagen in the lesions and skewed activated B cells toward Bregs in the spleen and peritoneal cavity of mice with endometriosis. In addition, the number of M2 macrophages decreased in the peritoneal cavity of Ibrutinib-treated mice compared to anti-CD20 and control mice. Depletion of B cells using an anti-CD20 antibody had no effect on activity and growth of endometriotic lesions and neither on the macrophages, compared to control mice.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

It is still unclear whether B cell depletion by the anti-CD20 or inactivation by Ibrutinib can prevent establishment and/or progression of endometriosis in humans.

WIDER IMPLICATIONS OF THE FINDINGS

Further investigation may contribute to clarifying the role of B cell subsets in human endometriosis.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by a grant of Institut National de la Santé et de la Recherche Médicale and Paris Descartes University. None of the authors has any conflict of interest to disclose.

Anti-inflammatory cytokines in endometriosis

Although the pathogenesis of endometriosis is not fully understood, it is often considered to be an inflammatory disease. An increasing number of studies suggest that differential expression of anti-inflammatory cytokines (e.g., interleukin-4 and -10, and transforming growth factor-β1) occurs in women with endometriosis, including in serum, peritoneal fluid and ectopic lesions. These anti-inflammatory cytokines also have indispensable roles in the progression of endometriosis, including by promoting survival, growth, invasion, differentiation, angiogenesis, and immune escape of the endometriotic lesions. In this review, we provide an overview of the expression, origin, function and regulation of anti-inflammatory cytokines in endometriosis, with brief discussion and perspectives on their future clinical implications in the diagnosis and therapy of the disease.

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.

Targeting IL-10 Family Cytokines for the Treatment of Human Diseases

Members of the interleukin (IL)-10 family of cytokines play important roles in regulating immune responses during host defense but also in autoimmune disorders, inflammatory diseases, and cancer. Although IL-10 itself primarily acts on leukocytes and has potent immunosuppressive functions, other family members preferentially target nonimmune compartments, such as tissue epithelial cells, where they elicit innate defense mechanisms to control viral, bacterial, and fungal infections, protect tissue integrity, and promote tissue repair and regeneration. As cytokines are prime drug targets, IL-10 family cytokines provide great opportunities for the treatment of autoimmune diseases, tissue damage, and cancer. Yet no therapy in this space has been approved to date. Here, we summarize the diverse biology of the IL-10 family as it relates to human disease and review past and current strategies and challenges to target IL-10 family cytokines for clinical use.

A Large-Cohort, Longitudinal Study Determines Precancer Disease Routes across Different Cancer Types

Although many diseases are associated with cancer, the full spectrum of temporal disease correlations across cancer types has not yet been characterized. A population-wide study of longitudinal disease trajectories is needed to interrogate the general medical histories of patients with cancer. Here we performed a retrospective study covering a 20-year period, using 6.9 million patients from the Danish National Patient Registry linked to 0.7 million patients with cancer from the Danish Cancer Registry. Statistical analysis identified all significant disease associations occurring prior to cancer diagnoses. These associations were used to build frequently occurring, longitudinal disease trajectories. Across 17 cancer types, a total of 648 significant diagnoses correlated directly with a cancer, while 168 diagnosis trajectories of time-ordered steps were identified for seven cancer types. The most common diseases across cancer types involved cardiovascular, obesity, and genitourinary diseases. A comprehensive, publicly available web tool of interactive illustrations for all cancer disease associations is provided. By exploring the precancer landscape using this large dataset, we identify disease associations that can be used to derive mechanistic hypotheses for future cancer research. SIGNIFICANCE: This study offers an innovative approach to examine prediagnostic disease and cancer development in a large national population-based setting and provides a publicly available tool to foster additional cancer surveillance research.

Targeted delivery of calreticulin to ED-A fibronectin leads to tumor-growth retardation

We report the design and characterization of novel fusion proteins, consisting of the F8 antibody and of murine calreticulin (Calr). The F8 antibody recognizes the alternatively-spliced ED-A domain of fibronectin, an extracellular matrix component found in most tumor types, while calreticulin has previously been described as an "eat-me" signal for dendritic cells and phagocytes. Four fusion proteins, differing in antibody formats and peptide linkers, were produced in mammalian cells, purified to homogeneity and tested in vitro and in vivo. A quantitative biodistribution in F9 tumor-bearing mice revealed that the homobivalent F8-F8-Calr format, featuring a tandem diabody structure, had the best tumor-homing properties and, for this reason, this protein was studied in therapy experiments in CT26 tumor-bearing mice. Intravenous administration of F8-F8-Calr led to a tumor growth retardation, which could be further improved by combination with anti-PD1 antibody treatment. Immunohistochemical analysis revealed an increased density of CD8⁺ T cells, CD11c⁺ dendritic cells and F4/80⁺ macrophages in tumor tissue. Even though F8-F8-Calr did not lead to cancer cures at the doses tested, the excellent tolerability profile and the ability to favor a leukocyte infiltration into the neoplastic mass suggests that the targeted delivery of calreticulin may be considered for combination therapy approaches.

Evolution of the magic bullet: Single chain antibody fragments for the targeted delivery of immunomodulatory proteins

Immunocytokines are fusion proteins that combine the specific antigen binding capacities of an antibody or derivative thereof and the potent bioactivity of a cytokine partner. These novel biopharmaceuticals have been directed to various targets of oncological as well as non-oncological origin and a handful of promising constructs are currently advancing in the clinical trial pipeline. Several factors such as the choice of a disease specific antigen, the antibody format and the modulatory nature of the payload are crucial, not only for therapeutic efficacy and safety but also for the commercial success of such a product. In this review, we provide an overview of the basic principles and obstacles in immunocytokine design with a specific focus on single chain antibody fragment-based constructs that employ interleukins as the immunoactive component. Impact statement Selective activation of the immune system in a variety of malignancies represents an attractive approach when existing strategies have failed to provide adequate treatment options. Immunocytokines as a novel class of bifunctional protein therapeutics have emerged recently and generated promising results in preclinical and clinical studies. In order to harness their full potential, multiple different aspects have to be taken into consideration. Several key points of these fusion constructs are discussed here and should provide an outline for the development of novel products based on an overview of selected formats.

Potency-matched Dual Cytokine-Antibody Fusion Proteins for Cancer Therapy

A novel biopharmaceutical, consisting of the F8 mAb (specific to a splice isoform of fibronectin) simultaneously fused to both TNF and IL2, was found to react with the majority of solid tumors and hematologic malignancies in mouse and man, but not with healthy adult tissues. The product selectively localized to neoplastic lesions in vivo, as evidenced by quantitative biodistribution studies using radioiodinated protein preparations. When the potency of the cytokine payloads was matched by a single-point mutation, the resulting fusion protein (IL2-F8-TNFmut) eradicated soft-tissue sarcomas in immunocompetent mice, which did not respond to individual antibody-cytokine fusion proteins or by standard doxorubicin treatment. Durable complete responses were also observed in mice bearing CT26, C1498, and F9 tumors. The simultaneous delivery of multiple proinflammatory payloads to the cancer site conferred protective immunity against subsequent tumor challenges. A fully human homolog of IL2-F8-TNFmut, which retained selectivity similar to its murine counterpart when tested on human material, may open new clinical applications for the immunotherapy of cancer. Mol Cancer Ther; 16(11); 2442-51. ©2017 AACR.

Tumor angiogenesis revisited: Regulators and clinical implications

Since Judah Folkman hypothesized in 1971 that angiogenesis is required for solid tumor growth, numerous studies have been conducted to unravel the angiogenesis process, analyze its role in primary tumor growth, metastasis and angiogenic diseases, and to develop inhibitors of proangiogenic factors. These studies have led in 2004 to the approval of the first antiangiogenic agent (bevacizumab, a humanized antibody targeting vascular endothelial growth factor) for the treatment of patients with metastatic colorectal cancer. This approval launched great expectations for the use of antiangiogenic therapy for malignant diseases. However, these expectations have not been met and, as knowledge of blood vessel formation accumulates, many of the original paradigms no longer hold. Therefore, the regulators and clinical implications of angiogenesis need to be revisited. In this review, we discuss recently identified angiogenesis mediators and pathways, new concepts that have emerged over the past 10 years, tumor resistance and toxicity associated with the use of currently available antiangiogenic treatment and potentially new targets and/or approaches for malignant and nonmalignant neovascular diseases.

Immunocytokines for cancer treatment: past, present and future

Immunocytokines are antibody-cytokine fusion proteins, with the potential to preferentially localize on tumor lesions and to activate anticancer immunity at the site of disease. Various tumor targets (e.g., cell membrane antigens and extracellular matrix components) and antibody formats (e.g., intact IgG and antibody fragments) have been considered for immunocytokine development and some products have advanced to clinical trials. In this review, we present relevant concepts and strategies for the design and use of anticancer immunocytokine products. In addition, we discuss emerging strategies for the pharmaceutical development and clinical application of this promising class of biopharmaceuticals.

Immunocytokines: a novel class of products for the treatment of chronic inflammation and autoimmune conditions

Antibody-cytokine fusion proteins, often referred to as immunocytokines, represent a novel class of biopharmaceutical agents that combine the disease-homing activity of certain antibodies with the immunomodulatory properties of cytokine payloads. Originally, immunocytokines were mainly developed for cancer therapy applications. More recently, however, the use of anti-inflammatory cytokines for the treatment of chronic inflammatory conditions and to treat autoimmune diseases has been considered. This review analyzes basic principles in the design of immunocytokines and describes the most advanced products in preclinical and clinical development.

Serum anti-inflammatory cytokines for the evaluation of inflammatory status in endometriosis

Background:

Endometriosis is a frequent gynecologic disease with a severe impact on the quality of life in the affected women; its pathogenesis is yet to be fully understood, with an altered immunity as a possible key factor. The present study aimed to investigate the serum anti-inflammatory cytokine profile in the patients with endometriosis compared with the healthy controls.

Materials and Methods:

One hundred and sixty women were included, divided into two study groups (Group I — endometriosis; Group 2 — healthy women). We evaluated the serum levels of interleukin-1 receptor antagonist (IL-1Ra), IL-2, IL-2R, IL-4, IL-10, IL-13, and IL-15 with the use of Human multiplex cytokine panels. Statistical analyses (normality distribution analysis, independent t-test, Mann–Whitney U-test) were performed using IBM SPSS software (version 22.0) and GraphPad Prism (version 5.00); receiver operating characteristic curve were used to demonstrate the diagnostic performance of the studied markers.

Results:

The mean serum level of IL-1Ra, IL-4, and IL-10 were significantly higher in women with endometriosis compared to women free of disease from the control group (30.155, 138.459, and 1.489, respectively, compared to 14.109, 84.710, and 0.688, respectively; P < 0.001, P < 0.001, and P = 0.002, respectively.). No significant differences in the mean serum levels of IL-2, IL-13, and IL-15 were observed between the studied groups and IL-2R had a very low detection rate.

Conclusion:

Endometriosis is associated with elevated levels of anti-inflammatory cytokines, IL-1Ra, IL-4, and IL-10, markers that have a potential role as a prognostic factor for endometriosis.

Alternatively Spliced EDA Domain of Fibronectin Is a Target for Pharmacodelivery Applications in Inflammatory Bowel Disease

The antibody-based pharmacodelivery of cytokines to sites of disease has been extensively studied for various indications but not for the treatment of inflammatory bowel diseases. Here, we report that the alternatively spliced EDA domain of fibronectin, a marker of angiogenesis and of tissue remodeling, is expressed in the dextran sodium sulfate mouse model of colitis and in patients with inflammatory bowel conditions, while being virtually undetectable in most normal adult tissues. Radiolabeled preparations of the F8 antibody, specific to the EDA domain of fibronectin, were shown to selectively localize to sites of inflammation in mice with colitis, as revealed by autoradiographic analysis. Fusion proteins of the F8 antibody with various murine payloads (interleukin-4, the p40 subunit of interleukin-12, interleukin-13) were administered to mice with colitis. IL12p40-F8 mediated an anti-inflammatory activity, which was comparable with the one of cyclosporine, whereas F8-IL4 did not inhibit colitis and F8-IL13 worsened the inflammatory conditions.

The Targeted Delivery of Interleukin 4 Inhibits Development of Endometriotic Lesions in a Mouse Model

Endometriosis is caused by the displacement of endometrium outside the uterus contributing heavily to infertility and debilitating pelvic pain. Ectopic adhesion and growth are believed to occur under the influence of a favorable hormonal environment and immunological factors. The objective of this study is to analyze the effect of a targeted therapy with an antibody-based pharmacodelivery of interleukin 4 (F8-IL4) in a mouse model of experimentally induced endometriosis. Endometriosis-like lesions were induced in Balb/c mice. The animals were treated intravenously with F8-IL4 or with untargeted IL4 (KSF-IL4). Twelve days after disease induction, the lesions were isolated. A significant reduction in the number of total lesions/mouse and in the total volume of lesions/mouse was observed in mice treated with F8-IL4 compared to controls (P = .029 and P = .006, respectively), while no difference was found between KSF-IL4-treated mice and their controls. Gene expression was evaluated by quantitative real-time polymerase chain reaction. Expression of genes involved in cell adhesion, extracellular matrix invasion, and neovascularization was significantly downregulated in F8-IL4-treated mice compared to their controls (integrin β1: P = .02; metalloproteinase [MMP] 3: P = .02; MMP9: P = .04; vascular endothelial growth factor: P = .04). Gene expression of inflammatory cytokines (tumor necrosis factor α, IL1β, IL1α, and IL6) did not vary in the ectopic lesions isolated from F8-IL4-treated mice compared to their controls. Immunohistochemistry demonstrated a significantly reduced expression of E-cadherin and β-catenin in the lesions of mice treated with F8-IL4. Our results show that the antibody-mediated targeted delivery of IL4 inhibits the development of endometriosis in a syngeneic mouse model by likely impairing adhesion, invasion, and vascularization of the ectopic endometrium.

Novel agents for the medical treatment of endometriosis

PURPOSE OF REVIEW

Current medical treatments for endometriosis-associated pain, including oral contraceptives, progestins and GnRH agonists, are partially effective and have significant side-effects. The purpose of this review is to present new hormonal and nonhormonal treatment for endometriosis.

RECENT FINDINGS

At present, the ideal drug that can prevent, inhibit or stop development of endometriosis, reduce associated pain or infertility and allow conception does not exist. New drugs in development for endometriosis modulate GnRH, estrogen and/or progesterone receptors, or target endometriosis-associated inflammation, angiogenesis, adhesion and/or tissue invasion. Most have been tested in rodents, and have been evaluated in more relevant animal models like nonhuman primates (baboons), but only a few, that is GnRH antagonists, have been tested in human randomized controlled trials. Important safety and efficacy issues remain a concern, as steroid receptors, inflammation, adhesion, angiogenesis and tissue invasion are key factors in physiological events like ovulation, menstruation and embryo implantation.

SUMMARY

New drugs for the medical treatment of endometriosis targeting both hormonal (GnRH, estrogen and progesterone receptors) and nonhormonal pathways (inflammation, angiogenesis, adhesions, tissue invasion) are promising, but their efficacy and safety need to be established in randomized human trials before they can be used in clinical practice.

Power over Pain: A Brief Review of Current and Novel Interventions for Endometriosis-Associated Pain

An estimated 10%-15% of women of reproductive age suffer from endometriosis and can be plagued with one or many forms of pain. It is no mystery that endometriosis is an extremely complex disease, with several factors leading to the predominant symptoms of infertility and pain. Although there are currently multiple options available for treating endometriosis-associated pain, none have the ability to completely relieve the symptoms. This review both highlights the current trends in treatment of endometriosis-associated pain and explores some novel options available for therapy directed towards oxidative stress, inflammation and nociceptive mechanisms of pain. A PubMed search was conducted to identify the most recent publications on the topic of pain associated with endometriosis, and further research was performed to clarify the mechanism by which current treatments target pain. Lastly, the authors include a review of pharmacological options at the forefront of endometriosis research. A more comprehensive understanding of the mechanisms behind endometriosis-associated pain will ultimately lead to more effective treatments and improved prognoses for patients.

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-mediated delivery of interleukin 4 to the neo-vasculature reduces chronic skin inflammation

BACKGROUND

The antibody-mediated delivery of cytokines ("immunocytokines") to sites of pathological angiogenesis represents an attractive strategy for the development of innovative biopharmaceuticals, capable of modulating the activity of the immune system in cancer and in chronic inflammatory conditions.

OBJECTIVE

Recombinant IL4 has previously been shown to be therapeutically active in patients with psoriasis. The antibody-mediated delivery of this cytokine to sites of chronic skin inflammatory conditions should lead to an improved potency and selectivity, compared to non-targeted IL4.

METHODS

The therapeutic activity of F8-IL4, a fusion protein of the F8 antibody (specific to the alternatively-spliced EDA domain of fibronectin) with murine IL4, was investigated in three immunocompetent mouse models of skin inflammation: two induced by the TLR7/8 ligand imiquimod (in Balb/c and C57BL/6) and one mediated by the over-expression of VEGF-A.

RESULTS

The EDA domain of fibronectin, a marker for angiogenesis, is expressed in the inflamed skin in all three models and F8-IL4 selectively localized to inflamed skin lesions following intravenous administration. The F8-IL4 fusion protein mediated a therapeutic benefit, which was superior to the one of a non-targeted version of IL4 and led to increased levels of key regulatory cytokines (including IL5, IL10, IL13, and IL27) in the inflamed skin, while IL2 levels were not affected in all treatment groups. A murine version of etanercept and a murine anti-IL17 antibody were used as positive control in the therapy experiments.

CONCLUSION

Skin inflammatory lesions can be selectively targeted using anti-EDA antibody-cytokine fusion proteins and the pharmacodelivery of IL4 confers a therapeutic benefit by shifting the cytokine balance.

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.

The dose-dependent tumor targeting of antibody-IFNγ fusion proteins reveals an unexpected receptor-trapping mechanism in vivo

Cytokines often display substantial toxicities at low concentrations, preventing their escalation for therapeutic treatment of cancer. Fusion proteins comprising cytokines and recombinant antibodies may improve the anticancer activity of proinflammatory cytokines. Murine IFNγ was appended in the diabody format at the C-terminus of the F8 antibody, generating the F8-IFNγ fusion protein. The F8 antibody is specific for the extra-domain A (EDA) of fibronectin, a tumor-associated antigen that is expressed in the vasculature and stroma of almost all tumor types. Tumor-targeting properties were measured in vivo using a radioiodinated preparation of the fusion protein. Therapy experiments were performed in three syngeneic murine models of cancer [F9 teratocarcinoma, WEHI-164 fibrosarcoma, and Lewis lung carcinoma (LLC)]. F8-IFNγ retained the biologic activity of both the antibody and the cytokine moiety in vitro, but, unlike the parental F8 antibody, it did not preferentially localize to the tumors in vivo. However, when unlabeled F8-IFNγ was administered before radioiodinated F8-IFNγ, a selective accumulation at the tumor site was observed. F8-IFNγ showed dose-dependent anticancer activity with a clear superiority over untargeted recombinant IFNγ. The anticancer activity was potentiated by combining with F8-IL4 without additional toxicities, whereas combination of F8-IFNγ with F8-TNF was lethal in all mice. Unlike other antibody-cytokine fusions, the use of IFNγ as payload for anticancer therapy is associated with a receptor-trapping mechanism, which can be overcome by the administration of a sufficiently large amount of the fusion protein without any detectable toxicity at the doses used.

Evaluation of antibody–chemokine fusion proteins for tumor-targeting applications

There is an increasing biotechnological interest in the ‘arming’ of therapeutic antibodies with bioactive payloads. While many antibody–cytokine fusion proteins have been extensively investigated in preclinical and clinical studies, there are only few reports related to antibody–chemokine fusion proteins (‘immunochemokines’). Here, we describe the cloning, expression, and characterization of 10 immunochemokines based on the monoclonal antibody F8, specific to the alternatively spliced extra domain A (EDA) of fibronectin, a marker of angiogenesis. Among the 10 murine chemokines tested in our study, only CCL19, CCL20, CCL21, and CXCL10 could be expressed and isolated at acceptable purity levels as F8-based fusion proteins. The immunochemokines retained the binding characteristics of the parental antibody, but could not be characterized by gel-filtration analysis, an analytical limitation which had previously been observed in our laboratory for the unconjugated chemokines. When radioiodinated preparations of CCL19-F8, CCL20-F8, CCL21-F8, and CXCL10-F8 were tested in quantitative biodistribution studies in tumor-bearing mice, the four fusion proteins failed to preferentially accumulate at the tumor site, while the unconjugated parental antibody displayed a tumor:blood ratio >20:1, 24 h after intravenous (i.v.) administration. The tumor-targeting ability of CCL19-F8 could be rescued only in part by preadministration of unlabeled CCL19-F8, indicating that a chemokine trapping mechanism may hinder pharmacodelivery strategies. While this article highlights expression, analytical, and biodistribution challenges associated with the antibody-based in vivo delivery of chemokines at sites of disease, it provides the first comprehensive report in this field and may facilitate future studies with immunochemokines.

From target discovery to clinical trials with armed antibody products

Conventional chemotherapy of serious conditions (e.g., cancer and chronic inflammatory diseases) relies on the use of potent bioactive agents, which do not preferentially localize at the site of disease and which may harm healthy tissues. Intense pharmaceutical research efforts are being devoted to the development of targeted therapeutic agents, capable of selectively homing to diseased tissues, while sparing normal body structures. Biological mass spectrometry and chemical proteomics have revolutionized the way targets for ligand-based pharmacodelivery applications are discovered. In this article, we present a personal account on research activities in the field for the last decade, outlining our experience in the discovery of accessible biomarkers and in the development of potent targeted therapeutic agents.

BIOLOGICAL SIGNIFICANCE

The present review discusses evolution of proteomic methodologies applied to the discovery of new targets for therapeutic intervention in cancer and inflammatory diseases. Chemical proteomics-driven target discovery allowed the development of new classes of antibody-based targeting biologics, which are having an impact in the oncological and chronic inflammation clinical research. This article is part of a Special Issue entitled: 20years of Proteomics in memory of Viatliano Pallini. Guest Editors: Luca Bini, Juan J. Calvete, Natacha Turck, Denis Hochstrasser and Jean-Charles Sanchez.

Latent cytokines for targeted therapy of inflammatory disorders

INTRODUCTION

The use of cytokines as therapeutic agents is important, given their potent biological effects. However, this very potency, coupled with the pleiotropic nature and short half-life of these molecules, has limited their therapeutic use. Strategies to increase the half-life and to decrease toxicity are necessary to allow effective treatment with these molecules.

AREAS COVERED

A number of strategies are used to overcome the natural limitations of cytokines, including PEGylation, encapsulation in liposomes, fusion to targeting peptides or antibodies and latent cytokines. Latent cytokines are engineered using the latency-associated peptide of transforming growth factor-β to produce therapeutic cytokines/peptides that are released only at the site of disease by cleavage with disease-induced matrix metalloproteinases. The principles underlying the latent cytokine technology are described and are compared to other methods of cytokine delivery. The potential of this technology for developing novel therapeutic strategies for the treatment of diseases with an inflammatory-mediated component is discussed.

EXPERT OPINION

Methods of therapeutic cytokine delivery are addressed. The latent cytokine technology holds significant advantages over other methods of drug delivery by providing simultaneously increased half-life and localised drug delivery without systemic effects. Cytokines that failed clinical trials should be reassessed using this delivery system.

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.

Association between interleukin-10 promoter polymorphisms and endometriosis: a meta-analysis

To investigate the influence of the interleukin-10 gene promoter polymorphisms on the susceptibility of endometriosis, we examined the association by performing a meta-analysis. The PubMed, Embase, HuGE Navigator and CNKI were searched to identify eligible studies. We then conducted a meta-analysis to examine the association between interleukin-10 gene promoter polymorphisms and endometriosis. Eight case-control studies which examined the association between the IL-10 gene promoter polymorphisms and the susceptibility to endometriosis were finally included in the meta-analysis. Meta-analysis of the IL-10 -592 A/C polymorphisms showed a significant increased risk of endometriosis in the overall and Asian population in all genetic models and allele contrast. However, meta-analysis of the IL-10 -1082 A/G and IL-10 -819 T/C polymorphisms showed no association with endometriosis in all genetic models and allele contrast in the overall and Asian population samples. In addition, there was not a significant association between the IL-10 -592 A/C gene promoter polymorphisms with the severity of endometriosis. In conclusion, this meta-analysis suggests that the IL-10 -592 A/C polymorphisms conferred susceptibility to endometriosis. However, no associations were found between the IL-10 -1082 A/G and -819 T/C polymorphisms and susceptibility to endometriosis. Further studies are required to elucidate these associations more clearly.

From IL-2 to IL-37: the expanding spectrum of anti-inflammatory cytokines

Feedback regulatory circuits provided by regulatory T cells (T(reg) cells) and suppressive cytokines are an intrinsic part of the immune system, along with effector functions. Here we discuss some of the regulatory cytokines that have evolved to permit tolerance to components of self as well as the eradication of pathogens with minimal collateral damage to the host. Interleukin 2 (IL-2), IL-10 and transforming growth factor-β (TGF-β) are well characterized, whereas IL-27, IL-35 and IL-37 represent newcomers to the spectrum of anti-inflammatory cytokines. We also emphasize how information accumulated through in vitro as well as in vivo studies of genetically engineered mice can help in the understanding and treatment of human diseases.

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.

Interfering with pH regulation in tumours as a therapeutic strategy

The high metabolic rate of tumours often leads to acidosis and hypoxia in poorly perfused regions. Tumour cells have thus evolved the ability to function in a more acidic environment than normal cells. Key pH regulators in tumour cells include: isoforms 2, 9 and 12 of carbonic anhydrase, isoforms of anion exchangers, Na+/HCO3- co-transporters, Na+/H+ exchangers, monocarboxylate transporters and the vacuolar ATPase. Both small molecules and antibodies targeting these pH regulators are currently at various stages of clinical development. These antitumour mechanisms are not exploited by the classical cancer drugs and therefore represent a new anticancer drug discovery strategy.