Novel ubiquitin-derived high affinity binding proteins with tumor targeting properties.

Targeting effector molecules to tumor cells is a promising mode of action for cancer therapy and diagnostics. Binding proteins with high affinity and specificity for a tumor target that carry effector molecules such as toxins, cytokines, or radiolabels to their intended site of action are required for these applications. In order to yield high tumor accumulation while maintaining low levels in healthy tissues and blood, the half-life of such conjugates needs to be in an optimal range. Scaffold-based binding molecules are small proteins with high affinity and short systemic circulation. Due to their low molecular complexity, they are well suited for combination with effector molecules as well as half-life extension technologies yielding therapeutics with half-lives adapted to the specific therapy. We have identified ubiquitin as an ideal scaffold protein due to its outstanding biophysical and biochemical properties. Based on a dimeric ubiquitin library, high affinity and specific binding molecules, so-called Affilin® molecules, have been selected against the extradomain B of fibronectin, a target almost exclusively expressed in tumor tissues. Extradomain B-binding molecules feature high thermal and serum stability as well as strong in vitro target binding and in vivo tumor accumulation. Application of several half-life extension technologies results in molecules of largely unaffected affinity but significantly prolonged in vivo half-life and tumor retention. Our results demonstrate the utility of ubiquitin as a scaffold for the generation of high affinity binders in a modular fashion, which can be combined with effector molecules and half-life extension technologies.

Glucocorticoid therapy of antigen-induced arthritis depends on the dimerized glucocorticoid receptor in T cells.

Despite several side effects, glucocorticoids (GCs) have been widely used for 60 y to treat rheumatoid arthritis on the basis of their antiinflammatory effects. However, the cells targeted by GCs and the transcriptional mechanisms underlying their actions through the glucocorticoid receptor (GR) in steroid therapy remain poorly defined. Using cell type-specific GR-deficient mice subjected to antigen-induced arthritis (AIA) as a model of human rheumatoid arthritis, we show that GC action on T cells but not myeloid cells is critical for therapeutic intervention in AIA. Furthermore, the resistance of mice expressing a DNA binding-defective GR (GR(dim)) to GC treatment reveals that dimerization of the GR is indispensable for the antiinflammatory effects. In these mice, the GC-induced suppression of T(H)1 and T(H)17 cell-derived proinflammatory cytokines is impaired. Our finding that IL-17A(-/-) mice are resistant to GC therapy, whereas IFN-γ(-/-) mice respond as efficiently as WT mice implies that IL-17-producing T cells and not IFN-γ-producing T cells are the most important targets for an efficient GC therapy. The present study's identification of the critical cell type and the mode of GR action in steroid therapy of AIA significantly advances our understanding of steroid therapy and should lead to therapies with greater efficiency and fewer side effects.

Liposomal encapsulation enhances and prolongs the anti-inflammatory effects of water-soluble dexamethasone phosphate in experimental adjuvant arthritis.

INTRODUCTION: The objective of this study was to evaluate the efficacy of intravenous (i.v.) injection of liposomally encapsulated dexamethasone phosphate (DxM-P) in comparison to free DxM-P in rats with established adjuvant arthritis (AA). This study focused on polyethylene glycol (PEG)-free liposomes, to minimize known allergic reactions caused by neutral PEG-modified (PEG-ylated) liposomes. METHODS: Efficacy was assessed clinically and histologically using standard scores. Non-specific and specific immune parameters were monitored. Activation of peritoneal macrophages was analyzed via cytokine profiling. Pharmacokinetics/biodistribution of DxM in plasma, synovial membrane, spleen and liver were assessed via mass spectrometry. RESULTS: Liposomal DxM-P (3 × 1 mg/kg body weight; administered intravenously (i.v.) on Days 14, 15 and 16 of AA) suppressed established AA, including histological signs, erythrocyte sedimentation rate, white blood cell count, circulating anti-mycobacterial IgG, and production of interleukin-1beta (IL-1ß) and IL-6 by peritoneal macrophages. The suppression was strong and long-lasting. The clinical effects of liposomal DxM-P were dose-dependent for dosages between 0.01 and 1.0 mg/kg. Single administration of 1 mg/kg liposomal DxM-P and 3 × 1 mg/kg of free DxM-P showed comparable effects consisting of a partial and transient suppression. Moreover, the effects of medium-dose liposomal DxM-P (3 × 0.1 mg/kg) were equal (in the short term) or superior (in the long term) to those of high-dose free DxM-P (3 × 1 mg/kg), suggesting a potential dose reduction by a factor between 3 and 10 by liposomal encapsulation. For at least 48 hours after the last injection, the liposomal drug achieved significantly higher levels in plasma, synovial membrane, spleen and liver than the free drug. CONCLUSIONS: This new PEG-free formulation of macrophage-targeting liposomal DxM-P considerably reduces the dose and/or frequency required to treat AA, with a potential to enhance or prolong therapeutic efficacy and limit side-effects also in the therapy of rheumatoid arthritis. Depot and/or recirculation effects in plasma, inflamed joint, liver, and spleen may contribute to this superiority of liposomally encapsulated DxM-P.

Regulatory T cells control the transition from acute into chronic inflammation in glucose-6-phosphate isomerase-induced arthritis.

OBJECTIVES: Glucose-6-phosphate isomerase (G6PI)-induced arthritis is a spontaneously remitting experimental arthritis model. It was hypothesised that regulatory T cells (Tregs) are involved in remission and their role in G6PI-induced arthritis was investigated. METHODS: Tregs were depleted by injection of anti-CD25 before immunisation of DBA/1 mice with G6PI. The severity of arthritis was assessed clinically and histologically and the number and function of G6PI-specific T helper (Th) cells were determined by flow cytometry. Th cells and monocytes/macrophages were depleted using anti-CD4 or clodronate-containing liposomes. RESULTS: Injection of anti-CD25 depleted Tregs transiently. Normal numbers of Tregs were restored 5 weeks after G6PI immunisation. Whereas arthritis started to resolve in control mice 3 weeks after immunisation with G6PI, severe arthritis was still present in the anti-CD25-treated mice 12 weeks after immunisation. The most striking ex vivo correlate of non-remitting arthritis was a strong increase in G6PI-specific Th cells 3 days after G6PI immunisation. This difference between treated and control mice declined at later time points. Depletion of CD4 cells ameliorated arthritis in controls but not in anti-CD25-treated mice. In contrast, clodronate-containing liposomes were an effective treatment in both groups. CONCLUSIONS: Tregs control the transition from acute self-limiting to non-remitting destructive G6PI-induced arthritis already in the preclinical disease stage. Once established, non-remitting destructive arthritis is not controlled by restoration of normal Treg numbers. These findings question the rationale of therapeutic approaches augmenting Treg number or function in established arthritis.

Separating therapeutic efficacy from glucocorticoid side-effects in rodent arthritis using novel, liposomal delivery of dexamethasone phosphate: long-term suppression of arthritis facilitates interval treatment.

INTRODUCTION: Glucocorticoids have extensively been used in the treatment of rheumatoid arthritis and other inflammatory diseases. However, their side-effects remain the major limitation in clinical use and an improved therapeutic index is needed. METHODS: Therapeutic efficacy and persistence of free and liposomal dexamethasone phosphate (DXM-P) were determined in mouse collagen-induced arthritis. For regimens with equal therapeutic benefit, the side-effect profiles were analysed over time with respect to collagen breakdown, suppression of the hypothalamus-pituitary-adrenal (HPA) axis, changes in blood glucose levels and the haematological profile. In addition, the presence of drug was monitored in plasma. RESULTS: Liposomal DXM-P, but not free drug, resulted in a persistent anti-inflammatory effect. Comparable clinical benefit was achieved with a single administration of 4 mg/kg liposomal DXM-P or daily administrations of 1.6 mg/kg free drug for at least 7 days. For the liposomal form, but not for the free form, we observed a limitation of the suppression of the HPA axis in time and an absence of the drug-induced gluconeogenesis. CONCLUSIONS: Liposomal DXM-P, but not free DXM-P, achieves therapeutic persistence in mouse collagen-induced arthritis, which results in drug-free periods of therapeutic benefit. The physical absence of drug after day 2 is associated with a reduction of the typical glucocorticoid side-effects profile. Liposomal DXM-P thereby has an improved therapeutic window.

Amphoteric liposomes enable systemic antigen-presenting cell-directed delivery of CD40 antisense and are therapeutically effective in experimental arthritis.

OBJECTIVE: Mediation of RNA interference by oligonucleotides constitutes a powerful approach for the silencing of genes involved in the pathogenesis of inflammatory disease, but in vivo application of this technique requires effective delivery to immune cells and/or sites of inflammation. The aim of the present study was to develop a new carrier system to mediate systemic administration of oligonucleotides to rheumatoid arthritis (RA) joints, and to develop an antisense oligonucleotide (ASO)-based approach to interfere with CD40-CD154 interactions in an experimental model of RA. METHODS: A novel liposomal carrier with amphoteric properties, termed Nov038, was developed and assessed for its ability to systemically deliver an ASO directed against CD40 (CD40-ASO). Male DBA/1 mice with collagen-induced arthritis were treated with Nov038-encapsulated CD40-ASO, and the effects of treatment on various parameters of disease activity, including clinical score, paw swelling, lymph node responses, and inflammatory cytokine production in the joints, were assessed. RESULTS: Nov038 was well tolerated, devoid of immune-stimulatory effects, and efficacious in mediating systemic oligonucleotide delivery to sites of inflammation. In mice with collagen-induced arthritis, Nov038 enabled the therapeutic administration of CD40-ASO and improved established disease, while unassisted CD40-ASO was ineffective, and anti-tumor necrosis factor alpha (anti-TNFalpha) treatment was less effective in this model. Nov038/CD40-ASO efficacy was attributed to its tropism for monocyte/macrophages and myeloid dendritic cells (DCs), resulting in rapid down-regulation of CD40, inhibition of DC antigen presentation, and reduction in collagen-specific T cell responses, as well as decreased levels of TNFalpha, interleukin-6 (IL-6), and IL-17 in arthritic joints. CONCLUSION: Amphoteric liposomes represent a novel carrier concept for systemic and antigen-presenting cell-targeted oligonucleotide delivery with clinical applicability and numerous potential applications, including target validation in vivo and inflammatory disease therapeutics. Moreover, Nov038/CD40-ASO constitutes a potent alternative to monoclonal antibody-based approaches for interfering with CD40-CD40L interactions.