Interleukin-1 receptor antagonist: role in biology

The interleukin-1 receptor antagonist (IL-1Ra) is a member of the IL-1 family that binds to IL-1 receptors but does not induce any intracellular response. Two structural variants of IL-1Ra have previously been described: a 17-kDa form that is secreted from monocytes, macrophages, neutrophils, and other cells (sIL-1Ra) and an 18-kDa form that remains in the cytoplasm of keratinocytes and other epithelial cells, monocytes, and fibroblasts (icIL-1Ra). An additional 16-kDa intracellular isoform of IL-1Ra has recently been described in neutrophils, monocytes, and hepatic cells. Both of the major isoforms of IL-1Ra are transcribed from the same gene through the use of alternative first exons. The two promoters regulating transcription of the secreted and intracellular forms have been cloned, and some of the functional cis-acting DNA regions have been characterized. The production of IL-1Ra is stimulated by many substances including adherent IgG, other cytokines, and bacterial or viral components. The tissue distribution of IL-1Ra in mice indicates that sIL-1Ra is found predominantly in peripheral blood cells, lungs, spleen, and liver, while icIL-1Ra is found in large amounts in skin. Studies in transgenic and knockout mice indicate that IL-1Ra is important in host defense against endotoxin-induced injury. IL-1Ra is produced by hepatic cells with the characteristics of an acute phase protein. Endogenous IL-1Ra is produced in numerous experimental animal models of disease as well as in human autoimmune and chronic inflammatory diseases. The use of neutralizing anti-IL-1Ra antibodies has demonstrated that endogenous IL-1Ra is an important natural antiinflammatory protein in arthritis, colitis, and granulomatous pulmonary disease. Treatment of human diseases with recombinant human IL-1Ra showed an absence of benefit in sepsis syndrome. However, patients with rheumatoid arthritis treated with IL-1Ra for six months exhibited improvements in clinical parameters and in radiographic evidence of joint damage.

Role of interleukin-1 (IL-1) in the pathogenesis of systemic onset juvenile idiopathic arthritis and clinical response to IL-1 blockade

Systemic onset juvenile idiopathic arthritis (SoJIA) encompasses ∼10% of cases of arthritis that begin in childhood. The disease is unique in terms of clinical manifestations, severity of joint involvement, and lack of response to tumor necrosis factor blockade. Here, we show that serum from SoJIA patients induces the transcription of innate immunity genes, including interleukin (IL)-1 in healthy peripheral blood mononuclear cells (PBMCs). Upon activation, SoJIA PBMCs release large amounts of IL-1β. We administered recombinant IL-1 receptor antagonist to nine SoJIA patients who were refractory to other therapies. Complete remission was obtained in seven out of nine patients and a partial response was obtained in the other two patients. We conclude that IL-1 is a major mediator of the inflammatory cascade that underlies SoJIA and that this cytokine represents a target for therapy in this disease.

Neonatal-onset multisystem inflammatory disease responsive to interleukin-1beta inhibition

BACKGROUND

Neonatal-onset multisystem inflammatory disease is characterized by fever, urticarial rash, aseptic meningitis, deforming arthropathy, hearing loss, and mental retardation. Many patients have mutations in the cold-induced autoinflammatory syndrome 1 (CIAS1) gene, encoding cryopyrin, a protein that regulates inflammation.

METHODS

We selected 18 patients with neonatal-onset multisystem inflammatory disease (12 with identifiable CIAS1 mutations) to receive anakinra, an interleukin-1-receptor antagonist (1 to 2 mg per kilogram of body weight per day subcutaneously). In 11 patients, anakinra was withdrawn at three months until a flare occurred. The primary end points included changes in scores in a daily diary of symptoms, serum levels of amyloid A and C-reactive protein, and the erythrocyte sedimentation rate from baseline to month 3 and from month 3 until a disease flare.

RESULTS

All 18 patients had a rapid response to anakinra, with disappearance of rash. Diary scores improved (P<0.001) and serum amyloid A (from a median of 174 mg to 8 mg per liter), C-reactive protein (from a median of 5.29 mg to 0.34 mg per deciliter), and the erythrocyte sedimentation rate decreased at month 3 (all P<0.001), and remained low at month 6. Magnetic resonance imaging showed improvement in cochlear and leptomeningeal lesions as compared with baseline. Withdrawal of anakinra uniformly resulted in relapse within days; retreatment led to rapid improvement. There were no drug-related serious adverse events.

CONCLUSIONS

Daily injections of anakinra markedly improved clinical and laboratory manifestations in patients with neonatal-onset multisystem inflammatory disease, with or without CIAS1 mutations. (ClinicalTrials.gov number, NCT00069329 [ClinicalTrials.gov].).

Costs, effects and C/E-ratios alongside a clinical trial

A general approach is discussed to assess the uncertainty surrounding the cost effectiveness ratio (C/E-ratio) estimated on the basis of data from a randomised clinical trial. The approach includes the calculation of a 95% probability ellipse and introduces the concept of a so called C/E-acceptability curve. This last curve defines for each predefined C/E-ratio the probability that the C/E-ratio found in the study is acceptable. The approach is illustrated by estimates of costs per life saved and costs per patient discharged alive on the basis of data from a phase II trial addressing the value of anakinra in treating sepsis syndrome.

Treatment of rheumatoid arthritis with recombinant human interleukin-1 receptor antagonist

OBJECTIVE

To evaluate the efficacy and safety of interleukin-1 receptor antagonist (IL-1Ra) in patients with rheumatoid arthritis (RA).

METHODS

Patients with active and severe RA (disease duration <8 years) were recruited into a 24-week, double-blind, randomized, placebo-controlled, multicenter study. Doses of nonsteroidal antiinflammatory drugs and/or oral corticosteroids (< or =10 mg prednisolone daily) remained constant throughout the study. Any disease-modifying antirheumatic drugs that were being administered were discontinued at least 6 weeks prior to enrollment. Patients were randomized to 1 of 4 treatment groups: placebo or a single, self-administered subcutaneous injection of IL-1Ra at a daily dose of 30 mg, 75 mg, or 150 mg.

RESULTS

A total of 472 patients were recruited. At enrollment, the mean age, sex ratio, disease duration, and percentage of patients with rheumatoid factor and erosions were similar in the 4 treatment groups. The clinical parameters of disease activity were similar in each treatment group and were consistent with active and severe RA. At 24 weeks, of the patients who received 150 mg/day IL-1Ra, 43% met the American College of Rheumatology criteria for response (the primary efficacy measure), 44% met the Paulus criteria, and statistically significant improvements were seen in the number of swollen joints, number of tender joints, investigator's assessment of disease activity, patient's assessment of disease activity, pain score on a visual analog scale, duration of morning stiffness, Health Assessment Questionnaire score, C-reactive protein level, and erythrocyte sedimentation rate. In addition, the rate of radiologic progression in the patients receiving IL-1Ra was significantly less than in the placebo group at 24 weeks, as evidenced by the Larsen score and the erosive joint count. IL-1Ra was well tolerated and no serious adverse events were observed. An injection-site reaction was the most frequently observed adverse event, and this resulted in a 5% rate of withdrawal from the study among those receiving IL-1Ra at 150 mg/day.

CONCLUSION

This study confirmed both the efficacy and the safety of IL-1Ra in a large cohort of patients with active and severe RA. IL-1Ra is the first biologic agent to demonstrate a beneficial effect on the rate of joint erosion.

Confirmatory interleukin-1 receptor antagonist trial in severe sepsis: a phase III, randomized, double-blind, placebo-controlled, multicenter trial. The Interleukin-1 Receptor Antagonist Sepsis Investigator Group

OBJECTIVE

To determine the therapeutic efficacy and safety of recombinant human interleukin-1 receptor antagonist (rhIL-1ra) in the treatment of patients with severe sepsis.

DESIGN

Prospective, randomized, double-blind, placebo-controlled, multicenter trial with a planned, midstudy, interim analysis.

SETTING

Ninety-one academic medical center intensive care units in North America and Europe.

PATIENTS

Patients with severe sepsis or septic shock (n = 696) received standard supportive care and antimicrobial therapy for sepsis, in addition to rhIL-1ra or placebo.

INTERVENTIONS

Patients were randomized to receive either rhIL-1ra (100 mg) or placebo (vehicle) by intravenous bolus, followed by a 72-hr continuous intravenous infusion of either rhIL-1ra (2.0 mg/kg/hr) or placebo.

MEASUREMENTS AND MAIN RESULTS

The study was terminated after an interim analysis found that it was unlikely that the primary efficacy end points would be met. The 28-day, all-cause mortality rate was 33.1% (116/350) in the rhIL-1ra treatment group, while the mortality rate in the placebo group was 36.4% (126/346), yielding a 9% reduction in mortality rate (p = .36). The patients were well matched at the time of study entry; 52.9% of placebo-treated patients were in shock while 50.9% of rhIL-1ra-treated patients were in shock at the time of study entry (p = .30). The mortality rate did not significantly differ between treatment groups when analyzed on the basis of site of infection, infecting microorganism, presence of bacteremia, shock, organ dysfunction, or predicted risk of mortality at the time of study entry. No excess number of adverse reactions or microbial superinfections were attributable to rhIL-1ra treatment in this study.

CONCLUSIONS

A 72-hr, continuous intravenous infusion of rhIL-1ra failed to demonstrate a statistically significant reduction in mortality when compared with standard therapy in this multicenter clinical trial. If rhIL-1ra treatment has any therapeutic activity in severe sepsis, the incremental benefits are small and will be difficult to demonstrate in a patient population as defined by this clinical trial.

Recombinant human interleukin 1 receptor antagonist in the treatment of patients with sepsis syndrome. Results from a randomized, double-blind, placebo-controlled trial. Phase III rhIL-1ra Sepsis Syndrome Study Group

OBJECTIVE

To further define the safety and efficacy of recombinant human interleukin 1 receptor antagonist (rhIL-1ra) in the treatment of sepsis syndrome.

STUDY DESIGN

Randomized, double-blind, placebo-controlled, multicenter, multinational clinical trial.

POPULATION

A total of 893 patients with sepsis syndrome received an intravenous loading dose of rhIL-1ra, 100 mg, or placebo followed by a continuous 72-hour intravenous infusion of rhIL-1ra (1.0 or 2.0 mg/kg per hour) or placebo.

OUTCOME MEASURE

Twenty-eight-day all-cause mortality.

RESULTS

There was not a significant increase in survival time for rhIL-1ra treatment compared with placebo among all patients who received the study medication (n = 893; generalized Wilcoxon statistic, P = .22) or among patients with shock at study entry (n = 713; generalized Wilcoxon statistic, P = .23), the two primary efficacy analyses specified a priori for this trial. Results from secondary analyses suggest an increase in survival time with rhIL-1ra treatment among patients with dysfunction of one or more organs (n = 563; linear dose-response, P = .009). Retrospective analysis demonstrated an increase in survival time with rhIL-1ra treatment among patients with a predicted risk of mortality of 24% or greater (n = 580; linear dose-response, P = .005) as well as among patients with both dysfunction of one or more organs and a predicted risk of mortality of 24% or greater (n = 411; linear dose-response, P = .002).

CONCLUSIONS

There was not a statistically significant increase in survival time for rhIL-1ra treatment compared with placebo among all patients who received the study medication or among patients with shock at study entry. Secondary and retrospective analyses of efficacy suggest that treatment with rhIL-1ra results in a dose-related increase in survival time among patients with sepsis who have organ dysfunction and/or a predicted risk of mortality of 24% or greater.

Interleukin-1, interleukin-1 receptors and interleukin-1 receptor antagonist

IL-1 (IL-1 alpha or IL-1 beta) is the prototypic "multifunctional" cytokine. Unlike the lymphocyte and colony stimulating growth factors, IL-1 affects nearly every cell type, and often in concert with other cytokines or small mediator molecules. Although some lymphocyte and colony stimulating growth factors may be therapeutically useful, IL-1 is a highly inflammatory cytokine and the margin between clinical benefit and unacceptable toxicity in humans is exceedingly narrow. In contrast, agents that reduce the production and/or activity of IL-1 are likely to have an impact on clinical medicine. In support of this concept, there is growing evidence that the production and activity of IL-1, particularly IL-1 beta, are tightly regulated events as if nature has placed specific "road blocks" to reduce the response to IL-1 during disease. In addition to controlling gene expression, synthesis and secretion, this regulation extends to surface receptors, soluble receptors and a receptor antagonist. Investigators have studied how production of the different members of the IL-1 family is controlled, the various biological activities of IL-1, the distinct and various functions of the IL-1 receptor (IL-1R) family and the complexity of intracellular signaling. Mice deficient in IL-1 beta, IL-1 beta converting enzyme (ICE) and IL-1R type I have also been studied. Humans have been injected with IL-1 (either IL-1 alpha or IL-1 beta) for enhancing bone marrow recovery and for cancer treatment. The IL-1 specific receptor antagonist (IL-1Ra) has also been tested in clinical trials.

The balance between IL-1 and IL-1Ra in disease

IL-1 is an important mediator of inflammation and tissue damage in multiple organs, both in experimental animal models of disease and in human diseases. The IL-1 family consists of two agonists, IL-1alpha and IL-1beta, two receptors, biologically active IL-1RI and inert IL-1RII, and a specific receptor antagonist, IL-1Ra. The balance between IL-1 and IL-1Ra in local tissues plays an important role in the susceptibility to and severity of many diseases. An allelic polymorphism in the IL-1Ra gene has been associated with a variety of human diseases primarily of epithelial and endothelial cell origin. This association may be secondary to an imbalance in the IL-1 system with enhanced production of IL-1beta and reduced production of the major intracellular isoform of IL-1Ra. Treatment of RA with daily subcutaneous injections of recombinant IL-1Ra protein has been shown to be efficacious. Gene therapy approaches with IL-1Ra are being evaluated for the treatment of RA and other human diseases.

Treatment of rheumatoid arthritis with anakinra, a recombinant human interleukin-1 receptor antagonist, in combination with methotrexate: results of a twenty-four-week, multicenter, randomized, double-blind, placebo-controlled trial

OBJECTIVE

To evaluate the efficacy and safety of anakinra in combination with methotrexate (MTX) in patients with active rheumatoid arthritis (RA).

METHODS

Patients with moderate-to-severe active RA who were receiving MTX for 6 consecutive months, with stable doses for > or = 3 months (those with disease duration of >6 months but <12 years) were randomized into 6 groups: placebo or 0.04, 0.1, 0.4, 1.0, or 2.0 mg/kg of anakinra administered in a single, daily, subcutaneous injection. The primary efficacy end point was the proportion of subjects who met the American College of Rheumatology 20% improvement criteria (attained an ACR20 response) at week 12.

RESULTS

A total of 419 patients were randomized in the study. Patient demographics and disease status were similar in the 6 treatment groups. The ACR20 responses at week 12 in the 5 active treatment plus MTX groups demonstrated a statistically significant (P = 0.001) dose-response relationship compared with the ACR20 response in the placebo plus MTX group. The ACR20 response rate in the anakinra 1.0-mg/kg (46%; P = 0.001) and 2.0-mg/kg (38%; P = 0.007) dose groups was significantly greater than that in the placebo group (19%). The ACR20 responses at 24 weeks were consistent with those at 12 weeks. Similar improvements in anakinra-treated subjects were noted in individual ACR components, erythrocyte sedimentation rate, onset of ACR20 response, sustainability of ACR20 response, and magnitude of ACR response. Anakinra was safe and well tolerated. Injection site reaction was the most frequently noted adverse event, and this led to premature study withdrawal in 7% (1.0-mg/kg group) to 10% (2.0-mg/kg group) of patients receiving higher doses.

CONCLUSION

In patients with persistently active RA, the combination of anakinra and MTX was safe and well tolerated and provided significantly greater clinical benefit than MTX alone.

Prevention of cold-associated acute inflammation in familial cold autoinflammatory syndrome by interleukin-1 receptor antagonist

BACKGROUND

Familial cold autoinflammatory syndrome (FCAS) is an autosomal dominant disorder characterised by recurrent episodes of rash, arthralgia, and fever after cold exposure. The genetic basis of this disease has been elucidated. Cryopyrin, the protein that is altered in FCAS, is one of the adaptor proteins that activate caspase 1, resulting in release of interleukin 1.

METHODS

An experimental cold challenge protocol was developed to study the acute inflammatory mechanisms occurring after a general cold exposure in FCAS patients and to investigate the effects of pretreatment with an antagonist of interleukin 1 receptor (IL-1Ra). ELISA, real-time PCR, and immunohistochemistry were used to measure cytokine responses.

FINDINGS

After cold challenge, untreated patients with FCAS developed rash, fever, and arthralgias within 1-4 h. Significant increases in serum concentrations of interleukin 6 and white-blood-cell counts were seen 4-8 h after cold challenge. Serum concentrations of interleukin 1 and cytokine mRNA in peripheral-blood leucocytes were not raised, but amounts of interleukin 1 protein and mRNA were high in affected skin. IL-1Ra administered before cold challenge blocked symptoms and increases in white-blood-cell counts and serum interleukin 6.

INTERPRETATION

The ability of IL-1Ra to prevent the clinical features and haematological and biochemical changes in patients with FCAS indicates a central role for interleukin 1beta in this disorder. Involvement of cryopyrin in activation of caspase 1 and NF-kappaB signalling suggests that it might have a role in many chronic inflammatory diseases.

RELEVANCE TO PRACTICE

These findings support a new therapy for a disorder with no previously known acceptable treatment. They also offer insights into the role of interleukin 1beta in more common inflammatory diseases.

Spectrum of clinical features in Muckle-Wells syndrome and response to anakinra

OBJECTIVE

Mutations in the NALP3/CIAS1/PYPAF1 gene are associated with the autoinflammatory diseases Muckle-Wells syndrome (MWS), familial cold autoinflammatory syndrome (FCAS), and neonatal-onset multisystem inflammatory disease (NOMID), which is also known as chronic infantile neurologic, cutaneous, articular (CINCA) syndrome. Molecular studies suggest that NALP3 is involved in the processing of interleukin-1beta (IL-1beta), prompting us to investigate whether IL-1 blockade may be therapeutic in patients with MWS.

METHODS

We reviewed the clinical features of 3 members of a family, all of whom had MWS associated with the NALP3 variant V200M (also designated V198M), and evaluated the response of their inflammatory disease to treatment with the recombinant human IL-1 receptor antagonist anakinra. The subjects kept a diary of symptoms and underwent fortnightly clinical and laboratory assessments, including measurement of the serum amyloid A protein concentration.

RESULTS

Each subject had fever, rashes, arthralgia, conjunctivitis, sensorineural deafness, and an intense acute-phase response characteristic of MWS. However, additional features were identified, including exacerbation of their disease by cold and neurologic manifestations, that have hitherto been described only in FCAS and NOMID, respectively. Clinical and serologic evidence of active inflammatory disease resolved rapidly and completely during treatment with anakinra.

CONCLUSION

The remarkable response of MWS to anakinra suggests that IL-1beta has a fundamental role in the pathogenesis of inflammation associated with mutations in the NALP3 gene, and supports study of IL-1 inhibition in patients with NOMID/CINCA syndrome or FCAS. The clinical features of the various syndromes associated with mutations in the NALP3 gene may overlap to a greater extent than has previously been recognized.

Blocking IL-1 in systemic inflammation

A growing number of systemic inflammatory diseases characterized in part by recurrent fevers, leukocytosis, anemia, and elevated acute phase proteins are linked to interleukin (IL)-1 activity since rapid and sustained resolution is observed upon specific blockade of IL-1 receptors. Rapid resolution of systemic and local inflammation is now also reported in systemic onset juvenile idiopathic arthritis (SoJIA). Loss of control of the secretion of IL-1β might be a common mechanism explaining the aberrant activity of IL-1 in these diseases.

Interleukin-1 receptor antagonist

IL-1ra is the first described naturally occurring receptor antagonist of any cytokine or hormone-like molecule. IL-1ra is a member of the IL-1 family by three criteria: amino acid sequence homology of 26 to 30% to IL-1 beta and 19% to IL-1 alpha; similarities in gene structure; and common gene localization to human chromosome 2q14. Two structural variants of IL-1ra exist: sIL-1ra, a secretory molecule produced by monocytes, macrophages, neutrophils, fibroblasts, and other cells; and icIL-1ra, an intracellular molecule produced by keratinocytes and other epithelial cells, macrophages, and fibroblasts. IL-1ra production by monocytes, macrophages, and neutrophils may be regulated in a differential fashion with IL-1 beta. Human IL-1ra binds to both human IL-1RIs and IL-1RIIs on cell surfaces, although with 100-fold greater avidity to IL-1RIs. IL-1ra may bind preferentially to soluble IL-1RIs and not at all to soluble IL-1RIIs. IL-1ra competitively inhibits binding of both IL-1 alpha and IL-1 beta to cell surface receptors without inducing any discernible intracellular responses. All three forms of IL-1 may bind to IL-1 receptors in a similar fashion but IL-1ra may lack the secondary interactions necessary to trigger cell responses. A 100-fold or greater excess of IL-1ra over IL-1 may be necessary to inhibit biological responses to IL-1 both in vitro and in vivo. The roles of sIL-1ra and icIL-1ra in normal physiology or in host defense mechanisms remain unclear. The administration of IL-1ra blocks the effects of IL-1 in some animal models of septic shock, inflammatory arthritis, graft-versus-host disease, and inflammatory bowel disease. The preliminary results of clinical trials in humans indicate possible efficacy of IL-1ra in sepsis syndrome, rheumatoid arthritis, and GVHD.

Neuroprotective effects of human recombinant interleukin-1 receptor antagonist in focal cerebral ischaemia in the rat

Recombinant human interleukin-1 receptor antagonist (rhIL-1ra) markedly protects against focal cerebral ischaemia in the rat, implicating endogenous IL-1 in the events leading to cerebral infarction. The present experiments investigated the effect of intracerebroventricular (i.c.v.) administration of IL-1 beta or rhIL-1ra on ischaemia damage and physiological parameters after permanent middle cerebral artery occlusion in the rat. IL-1 beta (5 ng. i.c.v.) markedly (92%) enhanced infarct volume and caused a significant rise in body temperature, but rhIL-1ra (10 micrograms, i.c.v.) significantly reduced infarct volume and did not significantly affect heart rate, blood pressure, or body temperature, rhIL-1ra administered 30 min before, or at the time of ischaemia significantly reduced infarct volume in cortex (55 and 60%, respectively) and striatum (52 and 41%, respectively). rhIL-1ra administered 30 min after ischaemia significantly reduced total and cortical infarct volume (26 and 29%, respectively), but did not significantly protect striatal tissue. The effects of rhIL-1ra were still evident in both cortex and striatum 7 days after ischaemia. These results support the role of IL-1 in ischaemic brain damage, revealing potent, sustained, neuroprotective effects of rhIL-1ra in the cortex and striatum, which cannot be attributed directly to changes in physiological parameters.

Rapid responses to anakinra in patients with refractory adult-onset Still's disease

OBJECTIVE

To assess the efficacy of anakinra treatment in patients with adult-onset Still's disease (AOSD) that is refractory to corticosteroids, methotrexate (MTX), and etanercept.

METHODS

Four patients with AOSD were treated with prednisone and MTX and 2 patients were also treated with etanercept for worsening symptoms and indicators of systemic inflammation. White blood cells (WBCs), C-reactive protein (CRP) levels and/or erythrocyte sedimentation rate, and ferritin levels were measured and, in 1 patient, serum creatinine levels were determined. Treatment with anakinra at 100 mg/day was initiated.

RESULTS

The index patient's disease was refractory to treatment with prednisone (30 mg/day) and MTX, with spiking fevers, rash, synovitis, a serum ferritin level of 8,400 ng/ml (normal 20,000/mm(3) with prominent neutrophilia, the CRP level rose to >200 mg/liter, and the ferritin level rose to >3,000 ng/ml. Upon restarting anakinra, the patient became afebrile, the WBC count fell to 8,000/mm(3), the CRP level fell to <3 mg/liter, and the ferritin level fell to <300 ng/ml. Three additional patients with refractory AOSD who experienced rapid reductions in fever, symptoms, and markers of inflammation when treated with anakinra are reported.

CONCLUSION

Refractory AOSD appears to be IL-1-mediated since anakinra decreases hematologic, biochemical, and cytokine markers and also produces rapid reductions in systemic and local inflammation. Reported efficacy of tumor necrosis factor-blocking therapies in AOSD may be due to a reduction in IL-1.

A multicenter, double-blind, dose-ranging, randomized, placebo-controlled study of recombinant human interleukin-1 receptor antagonist in patients with rheumatoid arthritis: radiologic progression and correlation of Genant and Larsen scores

OBJECTIVE

To evaluate radiographic progression and the relationship of radiologic scores obtained by the Genant and Larsen methods in a clinical trial of recombinant human interleukin-1 receptor antagonist (IL-1Ra).

METHODS

Patients with rheumatoid arthritis (RA) were randomized into 4 groups: placebo (n = 121) or IL-1Ra at a daily dosage of 30 mg (n = 119), 75 mg (n = 116), or 150 mg (n = 116). Hand radiographs obtained at baseline, 24 weeks, and 48 weeks were scored using both methods.

RESULTS

At 24 weeks, by the Genant method, there was significant reduction in the score for progression of joint space narrowing (JSN) and the total score (a combination of erosion and JSN) in all treatment groups. Least-squares mean changes in the Genant erosion score from baseline to 24 weeks were significantly reduced after treatment with IL-1Ra at 30 mg/day and for all IL-1Ra treatment groups combined. The changes corresponded to a reduction of 38% in erosion, 58% in JSN, and 47% in total score. Patients treated with IL-1Ra at 75 mg/day had a significant reduction in the Larsen erosive joint count (LEJC), and all IL-1RA-treated groups combined showed a 45% reduction. Correlations (r) between the Genant total and Larsen scores were 0.84 at baseline, 0.83 at week 24, and 0.83 at week 48 (P < 0.0001); correlations between the Genant erosion score and the LEJC were 0.83 (P < 0.0001) at all visits; correlations between the Genant total and the Larsen scores were 0.32 and 0.49 (P < 0.0001) for progression from baseline to week 24 and from baseline to week 48, respectively; correlations between the Genant erosion score and the LEJC were 0.36 and 0.41 (P < 0.0001) for progression to weeks 24 and 48, respectively.

CONCLUSION

IL-1Ra reduced radiologic progression of RA. Scores by the 2 methods correlated strongly for each individual time point, but much less strongly for assessments of disease progression.

Safety of extended treatment with anakinra in patients with rheumatoid arthritis

OBJECTIVE

To determine the safety profile of anakinra after extended exposure in a diverse clinical trial population of patients with rheumatoid arthritis.

METHODS

A six month, randomised, double blind phase comparing anakinra (100 mg/day) with placebo was followed by open label anakinra treatment for up to three years in patients with rheumatoid arthritis. Concomitant non-steroidal anti-inflammatory drugs, corticosteroids, and other disease modifying antirheumatic drugs were permitted.

RESULTS

In all 1346 patients with rheumatoid arthritis received anakinra for up to three years. Patients had varying levels of disease severity, concomitant drug use, and comorbid conditions. Cumulative, exposure adjusted event (EAE) rates for all adverse events (AEs), serious AEs, and deaths were similar during each year of anakinra treatment; the overall rate (0 to 3 years) was similar to that observed for controls during the blinded phase. The most frequent AEs were injection site reactions (122.26 events/100 patient-years), rheumatoid arthritis progression (67.80 events/100 patient-years), and upper respiratory infections (26.09 events/100 patient-years). The EAE rate of serious infections was higher for patients treated with anakinra for 0 to 3 years (5.37 events/100 patient-years) than for controls during the blinded phase (1.65 events/100 patient-years). However, if the patient was not receiving corticosteroid treatment at baseline, the serious infection rate was substantially lower (2.87 event/100 patient-years). The overall incidence of malignancies was consistent with expected rates reported by SEER. Neutralising antibodies developed in 25 patients, but appeared to be transient in 12; neutralising antibody status did not appear related to occurrence of malignancies or serious infections. There were no clinically significant trends in laboratory data related to anakinra.

CONCLUSION

Anakinra is safe and well tolerated for up to three years of continuous use in a diverse population of patients with rheumatoid arthritis.

Anticytokine strategies in the treatment of the systemic inflammatory response syndrome

The systemic inflammatory response syndrome (SIRS) is an acute illness characterized by generalized activation of the endothelium. The most severe form of the syndrome is found in patients with shock due to gram-negative sepsis. We examined both animal and limited human data for the contribution of cytokines to this syndrome. Cytokines are endogenously produced proteins of small molecular weight and multiple biological effects. The cytokines interleukin 1 (IL-1) and tumor necrosis factor (TNF), as well as interferon-gamma and interleukin 8, are discussed. Laboratory investigations suggest that these cytokines play a critical role in SIRS by promoting the biochemical and clinical characteristics of SIRS. The biochemical changes induced by TNF and IL-1 include increased synthesis of nitric oxide, prostaglandins, platelet-activating factor, and endothelial cell adhesion molecules. Specific blockade of TNF using neutralizing antibodies or soluble receptors to TNF in animal models of SIRS reduces mortality and severity of disease. Similar results have been observed blocking IL-1 using soluble IL-1 receptors or IL-1 receptor antagonists. Preliminary clinical studies suggest that blockade may be useful in treating human SIRS. The various strategies for blocking IL-1 and TNF are presented; in addition, their mechanism(s) of action and safety in humans are discussed. We conclude that based on animal studies and preliminary clinical trials, strategies to block IL-1 or TNF may benefit patients with the syndrome, although thorough clinical trials have not been completed.

A multicentre, double blind, randomised, placebo controlled trial of anakinra (Kineret), a recombinant interleukin 1 receptor antagonist, in patients with rheumatoid arthritis treated with background methotrexate

OBJECTIVE

To assess the efficacy and safety of 100 mg daily anakinra (Kineret), a recombinant form of the naturally occurring interleukin 1 receptor antagonist, plus methotrexate (MTX) in reducing the signs and symptoms of rheumatoid arthritis (RA).

METHODS

Patients with active RA (n = 506) despite current treatment with MTX were enrolled in this multicentre, double blind, randomised, placebo controlled study. Patients received subcutaneous injections of anakinra 100 mg/day or placebo. They were assessed monthly for 6 months for improvement in signs and symptoms of RA and for adverse events. The primary efficacy measure was the percentage of patients attaining ACR20 response at week 24.

RESULTS

Significantly greater proportions of patients treated with anakinra compared with placebo achieved ACR20 (38% v 22%; p<0.001), ACR50 (17% v 8%; p<0.01), and ACR70 (6% v 2%; p<0.05) responses. The response to anakinra was rapid; the proportion of patients with an ACR20 response at the first study assessment (4 weeks) was twice as high with anakinra as with placebo (p<0.005). Clinically meaningful and statistically significant responses were also seen in individual components of the ACR response (for example, Health Assessment Questionnaire, pain, C reactive protein levels, and erythrocyte sedimentation rate). Anakinra was well tolerated, with a safety profile, similar to that of placebo with one exception: mild to moderate injection site reactions were more common with anakinra than with placebo (65% v 24%).

CONCLUSIONS

This study confirms previous observations from a dose-ranging study showing that anakinra, in combination with MTX, is an effective and safe treatment for patients with RA who have inadequate responses to MTX alone.

Cytokines and anticytokines in the pathogenesis of sepsis

Clinical trials with anti-inflammatory agents in patients with sepsis are based on the assumption that excessive proinflammatory activity of the cytokine network negatively influences the outcome of severe bacterial infections. The failure of these trials to show clinical benefit, in conjunction with recent experimental data, raises doubt about the validity of this assumption. This article reevaluates the role of cytokines in the pathogenesis of sepsis and severe bacterial infections. The cytokine network is discussed as consisting of proinflammatory cytokines, antiinflammatory cytokines, and soluble inhibitors of proinflammatory cytokines.