Norihiro Nishimoto

Interleukin 6: from bench to bedside

Interleukin (IL)-6 is a pleiotropic cytokine that has important roles in the regulation of the immune response, inflammation, and hematopoiesis. Disruption of IL-6 regulation might, however, affect the immune response and consequently induce immune-mediated inflammatory diseases such as rheumatoid arthritis, systemic juvenile idiopathic arthritis, Castleman disease, and Crohns disease. Overproduction of IL-6 also contributes, through its roles as a growth factor or an antiapoptotic factor, to the development of malignant diseases such as multiple myeloma and renal cancer. Progress in the study of IL-6 has increased our understanding of the pathological roles of this cytokine in these diseases and provided key evidence that antagonizing its activities can be used as a therapeutic strategy. The application of molecular biology techniques to design monoclonal antibodies as therapeutic agents has made it possible to regulate the IL-6 signal to successfully treat diseases that have so far proved refractory to conventional therapies. Blocking IL-6 actions by use of a humanized antibody, tocilizumab, which targets the IL-6 receptor, has been proven to be therapeutically effective for rheumatoid arthritis, systemic juvenile idiopathic arthritis, Castleman disease and Crohns disease. In this review, we discuss a paradigm of IL-6 from basic science to clinical use.

Interleukin-6 in rheumatoid arthritis

Purpose of reviewRecent progress in cytokine studies has clarified the pathological roles played by cytokines and provided key evidence that antagonizing their actions can be therapeutic. The pathogenesis of rheumatoid arthritis, an autoimmune inflammatory disease, involves inflammatory cytokines such as tumour necrosis factor-α, interleukin-1 and interleukin-6. Anti-tumour necrosis factor-α and anti-interleukin-1 therapies have been used successfully to treat rheumatoid arthritis, but they are not consistently effective. We therefore need further therapies for this refractory disease. Interleukin-6 is another target molecule for blockade in the treatment of rheumatoid arthritis. Tocilizumab is a humanized antihuman interleukin-6 receptor monoclonal antibody designed to block the actions of interleukin-6. This review addresses the pathological significance of interleukin-6 and the current status of anti-interleukin-6 therapy for rheumatoid arthritis. Recent findingsThe safety and efficacy of tocilizumab have been demonstrated in clinical trials conducted in patients with rheumatoid arthritis and other autoimmune inflammatory diseases, such as juvenile idiopathic arthritis and Crohns disease. SummaryClinical studies have demonstrated the pathological significance of interleukin-6 and the safety and efficacy of anti-interleukin-6 therapy with tocilizumab. Blockade of interleukin-6 – the second generation of anticytokine therapy – may be a promising treatment for rheumatoid arthritis.

Consensus statement on blocking the effects of interleukin-6 and in particular by interleukin-6 receptor inhibition in rheumatoid arthritis and other inflammatory conditions

Background Since approval of tocilizumab (TCZ) for treatment of rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA), interleukin 6 (IL-6) pathway inhibition was evaluated in trials of TCZ and other agents targeting the IL-6 receptor and ligand in various RA populations and other inflammatory diseases. This consensus document informs on interference with the IL-6 pathway based on evidence and expert opinion. Methods Preparation of this document involved international experts in RA treatment and RA patients. A systematic literature search was performed that focused on TCZ and other IL6-pathway inhibitors in RA and other diseases. Subsequently, incorporating available published evidence and expert opinion, the steering committee and a broader expert committee (both including RA patients) formulated the current consensus statement. Results The consensus statement covers use of TCZ as combination- or monotherapy in various RA populations and includes clinical, functional and structural aspects. The statement also addresses the second approved indication in Europe JIA and non-approved indications. Also early phase trials involving additional agents that target the IL-6 receptor or IL-6 were evaluated. Safety concerns, including haematological, hepatic and metabolic issues as well as infections, are addressed likewise. Conclusions The consensus statement identifies points to consider when using TCZ, regarding indications, contraindications, screening, dose, comedication, response evaluation and safety. The document is aimed at supporting clinicians and informing patients, administrators and payers on opportunities and limitations of IL-6 pathway inhibition.

Interleukin-6 induces both cell growth and VEGF production in malignant mesotheliomas.

Malignant mesothelioma (MM), an incurable tumor, is reportedly an interleukin‐6 (IL‐6) secreting tumor. The pathological significance of IL‐6 overexpression in this tumor, however, has remained unclear. We investigated the biological functions of IL‐6 in mesotheliomas. Five mesothelioma cell lines were analyzed for IL‐6 production and IL‐6 receptor (IL‐6R) expression. Of them, 2 produced high levels of IL‐6, 2 produced intermediate levels and 1 cell line showed no secretion. All mesothelioma cell lines used in this study expressed very small amounts of IL‐6R mRNA. We compensated for this low level of IL‐6R expression in mesotheliomas by adding recombinant soluble IL‐6R (sIL‐6R) to mediate the IL‐6 signal. IL‐6 together with sIL‐6R was found to promote cell growth of H2052 and H226 MMs classified as high‐level IL‐6 producers in a dose‐dependent manner. Moreover, a humanized anti‐IL‐6R antibody (MRA) capable of blocking IL‐6 signaling suppressed the cell growth of mesotheliomas induced by IL‐6/sIL‐6R. These findings demonstrate that IL‐6 serves as an autocrine growth factor in the development of mesothelioma. In addition, IL‐6/sIL‐6R stimulation increased the expression of vascular endothelial growth factor (VEGF) in 4 out of 5 cell lines, and this induction was inhibited by MRA treatment. The involvement of the signal transducer and activator of transcription 3 (STAT3) pathway in both cell growth and VEGF induction by IL‐6/sIL‐6R was verified by dominant negative STAT3 transduction combined with adenovirus gene‐delivery methods. Although IL‐6 induces VEGF through the JAK2/STAT3 pathway, anti‐VEGF antibody could not inhibit the IL‐6‐induced cell growth observed in H2052 and H226. We concluded that IL‐6‐dependent growth does not occur via VEGF induction. These results suggest that treatment with anti‐IL‐6R antibody may constitute a potential molecular targeting therapy for MMs.

The therapy of autoimmune diseases by anti-interleukin-6 receptor antibody

Interleukin (IL)-6 plays essential roles not only in the immune response, but also in haematopoiesis and the central nervous system. Deregulated production of IL-6 has been found in chronic inflammatory autoimmune diseases, such as rheumatoid arthritis (RA), systemic onset juvenile idiopathic arthritis (soJIA), Crohn’s disease (CD) and systemic lupus erythematosus (SLE). Furthermore, IL-6 activities can explain many symptoms of these diseases. More importantly, serum levels of IL-6 are correlated with disease activity. Based on these facts, the authors planned to develop a humanised anti-IL-6 receptor antibody, tocilizumab (previously known as MRA), as a therapeutic agent for these inflammatory autoimmune diseases. Tocilizumab is a neutralising antibody to suppress IL-6 signalling mediated by both membranous and soluble IL-6R. Clinical efficacy of tocilizumab in RA, soJIA, adult-onset Still’s disease or CD patients has been discussed in this review. In all of these diseases, tocilizumab has improved the disease activity, suggesting that IL-6 plays an essential role in the pathogenesis of these diseases.

Drug free REmission/low disease activity after cessation of tocilizumab (Actemra) Monotherapy (DREAM) study

ObjectivesTo investigate the duration of remission and low disease activity (LDA) after cessation of tocilizumab (TCZ) treatment in rheumatoid arthritis patients who showed remission or LDA as assessed by DAS28 in response to preceding TCZ monotherapy, and to explore the factors contributing to prolonged efficacy duration.MethodsDisease activity was monitored for 56xa0weeks. The rate of continued efficacy was estimated by Kaplan–Meier curves.ResultsA total of 187 patients were eligible. At baseline of this study, median disease duration was 7.8xa0years, preceding TCZ treatment period was 4.0xa0years and DAS28 was 1.5. The rate of continued LDA at 52xa0weeks was 13.4xa0% according to the Kaplan–Meier estimate. 19 patients (10xa0%) were completely drug-free and 17 patients (9.1xa0%) fulfilled DAS28 remission at 52xa0weeks. Multivariate Cox regression analysis identified low serum IL-6 and normalisation of MMP-3 levels at cessation of TCZ as independent predictive markers for longer duration of LDA. In patients with low serum IL-6 (<12.9xa0pg/mL) and normal MMP-3 levels, the rate of continued LDA reached 38.0xa0% at 52xa0weeks.ConclusionsTCZ monotherapy may induce biologics-free remission or LDA without concomitant use of synthetic DMARDs. Serum levels of IL-6 and MMP-3 are useful markers for identifying patients who could discontinue TCZ without acute disease flare.

Establishment of a New Interleukin-6 (IL-6) Receptor Inhibitor Applicable to the Gene Therapy for IL-6-Dependent Tumor

Interleukin-6 (IL-6) is a key molecule involved in the pathogenesis of several inflammatory diseases and malignancies. Treatments that inhibit IL-6 mitigate the clinical conditions of such diseases. Here, we report on the development of a new receptor inhibitor of IL-6 (NRI) by genetically engineering tocilizumab, a humanized anti-IL-6 receptor monoclonal antibody which specifically blocks IL-6 signaling. This NRI consists of VH and VL of tocilizumab in a single-chain fragment format dimerized by fusing to the Fc portion of human immunoglobulin G(1). The binding activity to IL-6 receptor and the biological activity of the purified NRI were found to be similar to those of parental tocilizumab. Because NRI is encoded on a single gene, it is easily applicable to a gene delivery system using virus vehicles. We administered an adenovirus vector encoding NRI to mouse i.p. and monitored the serum NRI level and growth reduction property on S6B45, an IL-6-dependent multiple myeloma cell line, in vivo. Adequate amount of the serum NRI level to exert anti-IL-6 action could be obtained by the NRI gene introduction combined with adenovirus gene delivery, and this treatment inhibited the in vivo S6B45 cell growth significantly. These findings indicate that NRI is a promising agent applicable to the therapeutic gene delivery approach for IL-6-driven diseases.

Blocking the effects of interleukin-6 in rheumatoid arthritis and other inflammatory rheumatic diseases: systematic literature review and meta-analysis informing a consensus statement

Background Suppression of the immunoinflammatory cascade by targeting interleukin 6 (IL-6) mediated effects constitutes a therapeutic option for chronic inflammatory diseases. Tocilizumab is the only IL-6 inhibitor (IL-6i) licensed for rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA), but also other agents targeting either IL-6 or its receptor are investigated in various indications. Objective To review published evidence on safety and efficacy of IL-6i in inflammatory diseases. Methods We performed systematic literature searches in Medline and Cochrane, screened EULAR and American College of Rheumatology meeting-abstracts, and accessed http://www.clinicaltrials.gov. Results Comprehensive evidence supports the efficacy of tocilizumab in RA in DMARD-naïve patients, and after DMARD- and TNFi-failure. Randomised comparisons demonstrate superiority of tocilizumab in JIA, but not ankylosing spondylitis (AS). Other indications are currently investigated. Additional IL-6i show similar efficacy; safety generally appears acceptable. Conclusions IL-6i is effective and safe in RA and JIA, but not in AS. Preliminary results in other indications need substantiation.

Enhanced production of osteopontin in multiple myeloma: clinical and pathogenic implications

Summary. In this study, we examined osteopontin (OPN) production in myeloma cells and plasma OPN levels in multiple myeloma (MM) patients. We assessed OPN production in bone marrow cells (BMCs) by immunocytochemistry and enzyme‐linked immunosorbent assay (ELISA). We also assessed OPN production in various B‐cell malignant cell lines, including three myeloma cell lines by reverse transcription polymerase chain reaction (RT‐PCR) and Western blotting. In addition, we measured plasma OPN concentrations by ELISA in 30 MM patients, 21 monoclonal gammopathy of undetermined significance (MGUS) patients and 30 healthy volunteers. As a result, in an immunocytochemical study, abundant OPN was detected in BMCs from overt MM patients, whereas no OPN was detected in BMCs from patients with other haematological diseases, including MGUS. Cultured BMCs from overt MM patients produced more OPN than those from patients with either smouldering MM or MGUS. Myeloma cell lines spontaneously produced OPN. Plasma OPN levels of MM patients were significantly higher than those of MGUS patients and healthy volunteers (Pu2003<u20030·05). Moreover, they correlated with both progression and bone destruction of the disease (Pu2003<u20030·05). These suggest that myeloma cells actively produce OPN, which possibly contributes to osteoclastic bone resorption in MM. Plasma OPN levels may be a useful biomarker for assessing bone destruction in MM and distinguishing MM from MGUS or smouldering MM.

Anti-Interleukin-6 Receptor Antibody Therapy in Rheumatic Diseases

In the treatment of rheumatic diseases such as rheumatoid arthritis (RA) or systemic onset juvenile idiopathic arthritis (soJIA), new therapies targeting pro-inflammatory cytokines have been developed. IL-6 is a pleiotropic cytokine with a wide range of biological activities including a pro-inflammatory mediator activity. Overproduction of IL-6 has been reported to be pathologically involved in the rheumatic diseases and, therefore, blockade of IL-6 actions may improve the disease. Tocilizumab, a humanized monoclonal antibody against human interleukin-6 receptor (IL-6R), inhibits IL-6 binding to IL-6R and specifically interferes with IL-6 actions. Castlemans disease is an atypical lymphoproliferative disorder caused by the overproduction of IL-6. Tocilizumab therapy improves immunological and hematological abnormalities as well as systemic inflammatory symptoms including wasting. This translational study also confirmed the pathological significance of IL-6 in the disease. RA is a representative autoimmune inflammatory disease characterized by bone and cartilage destruction in multiple joints. Since IL-6 also plays pathological roles in RA, tocilizumab therapy has been introduced to the patients with refractory disease and has shown a strong therapeutic effect. Besides Castlemans disease and RA, tocilizumab has been shown to be effective for patients with soJIA and Crohns disease. Tocilizumab treatment is generally well tolerated and safe. Therefore, tocilizumab can be a promising therapeutic agent for the rheumatic diseases in which IL-6 overproduction is pathologically involved.