The IL-17 Family of Cytokines in Health and Disease.

The interleukin 17 (IL-17) family of cytokines contains 6 structurally related cytokines, IL-17A through IL-17F. IL-17A, the prototypical member of this family, just passed the 25th anniversary of its discovery. Although less is known about IL-17B-F, IL-17A (commonly known as IL-17) has received much attention for its pro-inflammatory role in autoimmune disease. Over the past decade, however, it has become clear that the functions of IL-17 are far more nuanced than simply turning on inflammation. Accumulating evidence indicates that IL-17 has important context- and tissue-dependent roles in maintaining health during response to injury, physiological stress, and infection. Here, we discuss the functions of the IL-17 family, with a focus on the balance between the pathogenic and protective roles of IL-17 in cancer and autoimmune disease, including results of therapeutic blockade and novel aspects of IL-17 signal transduction regulation.

Therapeutic potential of targeting IL-17.

A June 2012 meeting in Dublin, Ireland, showcased advances in the understanding of the role of IL-17 and related cytokines in host immunity and how these cytokines have been successfully targeted for the treatment of autoimmunity.

Differential Roles for Interleukin-23 and Interleukin-17 in Intestinal Immunoregulation.

Interleukin-23 (IL-23) and IL-17 are cytokines currently being targeted in clinical trials. Although inhibition of both of these cytokines is effective for treating psoriasis, IL-12 and IL-23 p40 inhibition attenuates Crohn's disease, whereas IL-17A or IL-17 receptor A (IL-17RA) inhibition exacerbates Crohn's disease. This dichotomy between IL-23 and IL-17 was effectively modeled in the multidrug resistance-1a-ablated (Abcb1a(-/-)) mouse model of colitis. IL-23 inhibition attenuated disease by decreasing colonic inflammation while enhancing regulatory T (Treg) cell accumulation. Exacerbation of colitis by IL-17A or IL-17RA inhibition was associated with severe weakening of the intestinal epithelial barrier, culminating in increased colonic inflammation and accelerated mortality. These data show that IL-17A acts on intestinal epithelium to promote barrier function and provide insight into mechanisms underlying exacerbation of Crohn's disease when IL-17A or IL-17RA is inhibited.

Brodalumab in psoriatic arthritis: results from the randomised phase III AMVISION-1 and AMVISION-2 trials.

OBJECTIVE: To compare the efficacy and safety of brodalumab, an interleukin-17 receptor subunit A inhibitor, with placebo, in patients with psoriatic arthritis (PsA). METHODS: Adult patients with active PsA and inadequate response to, or intolerance to, conventional treatment were enrolled into two phase III studies (NCT02029495 and NCT02024646) and randomised 1:1:1 to receive subcutaneous brodalumab 140 mg or 210 mg or placebo at weeks 0, 1 and every 2 weeks up to 24 weeks. About 30% of patients had prior use of biologics. The primary endpoint for both studies was the American College of Rheumatology 20 (ACR20) response at week 16. RESULTS: 962 patients were randomised across the studies prior to early termination due to sponsor decision. The primary endpoint was met in both studies. Based on comparable design and eligibility criteria, data from both studies were pooled. Significantly more patients achieved ACR20 at week 16 in both brodalumab treatment groups (45.8% and 47.9% for 140 mg and 210 mg, respectively) versus placebo (20.9%) (p<0.0001). Similar results were observed at week 24. Significantly higher proportions of patients receiving brodalumab achieved ACR50/70, Psoriasis Area and Severity Index 75/90/100 and resolution of dactylitis and enthesitis versus placebo (p<0.01). Adverse event rates were similar across treatments at week 16 (54.4%, 51.6% and 54.5% for placebo, brodalumab 140 mg and 210 mg, respectively). No new safety signals were reported. CONCLUSION: Brodalumab was associated with rapid and significant improvements in signs and symptoms of PsA versus placebo. Brodalumab was well tolerated, with a safety profile consistent with other interleukin-17 inhibitors.

IL-17A Recruits Rab35 to IL-17R to Mediate PKCα-Dependent Stress Fiber Formation and Airway Smooth Muscle Contractility.

IL-17A is a critical proinflammatory cytokine for the pathogenesis of asthma including neutrophilic pulmonary inflammation and airway hyperresponsiveness. In this study, by cell type-specific deletion of IL-17R and adaptor Act1, we demonstrated that IL-17R/Act1 exerts a direct impact on the contraction of airway smooth muscle cells (ASMCs). Mechanistically, IL-17A induced the recruitment of Rab35 (a small monomeric GTPase) and DennD1C (guanine nucleotide exchange factor [GEF]) to the IL-17R/Act1 complex in ASMCs, resulting in activation of Rab35. Rab35 knockdown showed that IL-17A-induced Rab35 activation was essential for protein kinase Cα (PKCα) activation and phosphorylation of fascin at Ser39 in ASMCs, allowing F-actin to interact with myosin to form stress fibers and enhance the contraction induced by methacholine. PKCα inhibitor or Rab35 knockdown indeed substantially reduced IL-17A-induced stress fiber formation in ASMCs and attenuated IL-17A-enhanced, methacholine-induced contraction of airway smooth muscle. Taken together, these data indicate that IL-17A promotes airway smooth muscle contraction via direct recruitment of Rab35 to IL-17R, followed by PKCα activation and stress fiber formation.

Three-year U.S. pharmacovigilance report of brodalumab.

Brodalumab, an interleukin-17 receptor A antagonist, is approved for treatment of moderate-to-severe plaque psoriasis in adults without response or with loss of response to other systemic therapies. In the United States, there is a boxed warning for brodalumab regarding suicidal ideation and behavior; however, no causal relationship between brodalumab and suicidality was established during pivotal trials. In the 2-year pharmacovigilance data, no completed suicides or suicide attempts were reported. The most frequent adverse event (AE) was arthralgia. The safety profile of brodalumab is now being updated after 3 years of pharmacovigilance data. Here, we outline pharmacovigilance data reported to Ortho Dermatologics by patients and healthcare professionals in the United States from August 15, 2017, to August 14, 2020. Brodalumab exposure estimates were obtained by calculating the time between first and last prescription-dispensing authorization dates. Data from 1854 patients were collected, and brodalumab exposure was estimated to be 2736 patient-years. The most frequent AE was arthralgia (111 events; 0.04 events per patient-year). One episode of suicide attempt was reported in a patient with a history of depression. No completed suicides were reported. There were 81 serious infections reported, none of which were fungal. Over the 3-year period, 30 malignancies occurred in 25 patients, none of which were determined to be related to brodalumab. Three-year pharmacovigilance data are consistent with the safety profile of brodalumab previously reported in long-term analyses of clinical trials and the 2-year pharmacovigilance data.

Short-term transcriptional response to IL-17 receptor-A antagonism in the treatment of psoriasis.

BACKGROUND: IL-17 antagonists induce impressive clinical benefits in psoriasis, but it is unknown to what extent cellular and molecular psoriasis characteristics are suppressed by a clinically relevant dose/schedule of any IL-17-receptor antagonist. OBJECTIVE: We sought to examine the effects of the IL-17 receptor-A antagonist brodalumab, on clinical and molecular psoriasis features over a 12-week period. METHODS: A subset of patients (n = 116) enrolled in 3 phase-3 randomized clinical trials (AMAGINE -1 [Efficacy, Safety, and Withdrawal and Retreatment With Brodalumab in Moderate to Severe Plaque Psoriasis Subjects], -2 [P3 Study Brodalumab in Treatment of Moderate to Severe Plaque Psoriasis], and -3 [Efficacy and Safety of Brodalumab Compared With Placebo and Ustekinumab in Moderate to Severe Plaque Psoriasis in Subjects]) participated in a mechanistic substudy where punch biopsies were collected (lesional and nonlesional skin) between baseline and 12 weeks. This cohort included moderate-to-severe psoriasis patients treated with 140 mg (n = 46), 210 mg (n = 41) brodalumab, or placebo (n = 29). Key epidermal psoriatic features, including T-cell and dendritic cell subsets, were examined using immunohistochemistry. Treatment-induced changes in lesional skin gene expression profiles were evaluated using Affymetrix arrays. RESULTS: IL-17 receptor-A antagonism caused extensive improvements in clinical, histologic, and transcriptomic features of psoriasis. Cellular infiltrates (CD3+, CD8+, CD11c+, CD163+), markers of keratinocyte proliferation (Ki67+, KRT16), and inflammatory cytokines (IL-17A/C/F, IL-23A, IL-12B) decreased progressively, reaching close to nonlesional levels, paralleled by decreases in epidermal thickness. Psoriasis transcriptome gene expression improved ∼85% to 95% in responders whose psoriasis area severity index improved by 75% from baseline by week 12 (n = 63), compared with ∼30% to 65% in nonresponders (n = 12), while the residual disease genomic profile was 10% of the psoriasis transcriptome, which is less than for earlier generation drugs. IL-17-dependent gene expression, including keratinocyte genes, improved earlier and more extensively following brodalumab treatment compared with ustekinumab treatment (anti-IL-23/-IL-12). CONCLUSIONS: The clinically approved dose and schedule for brodalumab leads to nearly complete resolution of clinical, histologic, and transcriptomic features of psoriasis. Evidently, IL-17-induced release of keratinocyte-derived inflammatory mediators is a key driver of psoriasis pathogenesis.

Real-World Clinical Experience With the IL-17 Receptor A Antagonist Brodalumab

Psoriasis is a chronic, inflammatory, remitting/relapsing autoimmune dermatologic condition that manifests with scaly, erythematous plaques. It has a significantly negative effect on patient quality of life, as well as increasing their risk of numerous comorbid diseases. Patients are typically treated initially with topical steroids, retinoids, and vitamin D derivatives followed by phototherapy and systemic treatments, including oral, subcutaneous or intravenous immunomodulatory drugs, if needed. Psoriasis is driven by T-cell activation and associated with the secretion of proinflammatory cytokines and a dysregulated interleukin-23/T helper 17 (Th-17) inflammatory response. Eleven biologic therapies and 6 biosimilars that target the 3 main immunological pathways­tumor necrosis factor-α (TNF-α), interleukin 23 (IL-23), and IL-17, are approved for the treatment of plaque psoriasis. While most demonstrate similar effectiveness in clinical trials, patient response in real-world settings is varied. Thus, it is important that the clinician understand the mechanism of action of these drugs as well as their safety profile, unique benefits, and limitations. They must also consider the patient's disease presentation, severity, and comorbid conditions when determining the most appropriate therapy. This article focuses on the IL-17 inhibitors, secukinumab, ixekizumab, and brodalumab, highlighting their unique mechanisms of action and their efficacy and safety in a real-world clinical setting. J Drugs Dermatol. 2020;19(2)132-136. doi:10.36849/JDD.2020.4774

Clinical and Molecular Effects of Interleukin-17 Pathway Blockade in Psoriasis

The interleukin-17 (IL-17) pathway plays a crucial role in the development of psoriasis. Briefly, naive T cells differentiate into helper T (Th17) cells through interaction with activated dendritic cells in the presence of IL-23, Th17 cells produce IL-17 cytokines, and keratinocytes stimulated by IL-17 ligands lead to aberrant differentiation and proliferation that promote production of proinflammatory chemokines and further recruitment of inflammatory cells, setting up a positive feedback loop. Currently, 3 US Food and Drug Administration­approved agents to treat psoriasis affect the IL-17 pathway: brodalumab, secukinumab, and ixekizumab. Brodalumab is a fully human IL-17 receptor A antagonist that blocks signaling of multiple downstream inflammatory cytokines involved in psoriasis. Secukinumab and ixekizumab selectively bind to and neutralize only IL-17A. Pharmacologic effects in patients with psoriasis include decreased keratinocyte hyperproliferation, reduced epidermal thickening, decreased inflammatory markers, and resolution of histologic and genomic features of psoriasis. In clinical trials, therapeutic doses of brodalumab, secukinumab, and ixekizumab have demonstrated skin clearance efficacy by psoriasis area and severity index and static physician's global assessment scores at 12 weeks. The immunomodulation of these agents is associated with a favorable safety profile. Overall, the clinical improvement and normalization of genetic hallmarks of psoriasis provide a strong case for the unique role of IL-17 receptor blocking as a therapeutic mechanism of action to treat psoriasis. Understanding the unique mechanisms by which treatments interact with the IL-17 pathway to inhibit downstream proinflammatory signal cascade can help physicians make informed treatment decisions when selecting the appropriate medication for patients. J Drugs Dermatol. 2020;19(2)138-143. doi:10.36849/JDD.2020.4645

Role of IL-17A receptor blocking in melanocyte survival: A strategic intervention against vitiligo.

Cytokines regulate immune response and inflammation and play an important role in depigmentation process of an autoimmune disease, vitiligo. We sought to determine how inflammatory cytokines influence the progression of vitiligo, and based on that, we develop a logical therapeutic intervention using primary melanocyte culture. Melanocytes were cultured and exposed to IL-17A, IL-1ß, IFN-γ and TGF-ß for 4 days. Melanocytes proliferation, tyrosinase assay and melanin content were measured. Real-Time PCR was used to analyse mRNA expression of genes specific for melanocytes growth and pigmentation. Anti-IL-17A receptor antibody was used to block IL-17A receptors expressed on melanocytes. Protein expression of MITF and TYR was assessed by immunofluorescence and Western blotting. A gradual decline in the melanocyte population, melanin content and tyrosinase activity was observed after different cytokine treatment. The expression of MITF and its downstream genes after blocking with anti-IL-17RA, an increased melanin content, increased expression of TYR, MITF along with its downstream genes, and cell proliferation was observed.

New insights in neutrophilic asthma.

PURPOSE OF REVIEW: Recent advances in both murine models and clinical research of neutrophilic asthma are improving our understanding on the etiology and pathophysiology of this enigmatic endotype of asthma. We here aim at providing an overview of our current and latest insights on the pathophysiology and treatment of neutrophilic asthma. RECENT FINDINGS: Activation of the NLRP3 inflammasome pathway with increased IL-1ß has been demonstrated in various studies involving patients with asthma. It has been suggested that type 3 innate lymphoid cells are implicated in the inflammatory cascade leading to neutrophilic inflammation. The role of neutrophil extracellular traps is only at the start of being understood and might be an attractive novel therapeutic target. A diverse panel of nonallergic stimuli, such as cigarette smoke, intensive exercise, cold air or saturated fatty acids, have been linked with neutrophilic airway inflammation. Azithromycin treatment could reduce asthma exacerbations and quality of life in patients with persistent asthma. SUMMARY: Research of the last few years has accelerated our insights in mechanisms underlying neutrophilic asthma. This is in stark contrast with the lack of efficacy of different therapies targeting neutrophil chemotaxis and/or signalling cascade, such as IL-17A or CXCR2. Macrolide therapy might be a useful add-on therapy for patients with persistent asthma.

Biologics for psoriasis: What is new?

Etiology of psoriasis is unclear but environmental, genetic, and immune factors act significant roles in the pathogenesis of this disease. Helper T cells (TH), plasmoid, and dermal dendritic cells play a prominent role in the development of classical psoriatic lesions. Interleukin stimulation is another important process in the pathogenesis of the disease that directly influences keratinocytes and leading to the formation of psoriatic pattern in the skin. Tumor necrosis factor (TNF) α which releases from keratinocytes activates dendritic cells in the early stages of complex pathogenesis of psoriasis. Activated keratinocytes also produce other proinflammatory cytokines (IL-1b and IL-6), antimicrobial peptides, and various chemokines. TNF activates dendritic cells that produce IL-23, leading to TH17 differentiation. TH17 cells secrete IL-17A, which has been shown to promote psoriatic skin changes. Consequently, after clarification of these main pathological mechanisms, anti-IL therapies have been accepted as a major treatment for patients with moderate-to-severe psoriasis. Here, actual information will be presented about biological agents currently in clinical use or being tested for clinical application for treatment of patients with psoriasis.

Blockade of IL-17A/IL-17R Pathway Protected Mice from Sepsis-Associated Encephalopathy by Inhibition of Microglia Activation.

Sepsis-associated encephalopathy (SAE) is a poorly understood condition that leads to long-term cognitive impairment and increased mortality in survivors. Recent research revealed that IL-17A/IL-17R might serve as a checkpoint in microglia-mediated neuroinflammation. The present study was designed to determine the specific role of IL-17A-mediated microglia activation in the development of SAE. A mouse model of SAE was induced by cecal ligation and puncture (CLP), and behavior performance was evaluated by the inhibitory avoidance test and the open field test. Cytokine expression and microglia activation in brain tissue were determined at 6 h, 12 h, 24 h, 48 h, and day 7 post surgery. Further, septic mice were intracerebral ventricle- (i.c.v.-) injected with recombinant IL-17A, anti-IL-17A ab, anti-IL-17R ab, or isotype controls to evaluate the potential effects of IL-17A/IL-17R blockade in the prevention of SAE. Septic peritonitis induced significant impairment of learning memory and exploratory activity, which was associated with a higher expression of IL-17A, IL-1ß, and TNF-α in the brain homogenate. Fluorescence intensity of Iba-1 and IL-17R in the hippocampus was significantly increased following CLP. Treatment with recombinant IL-17A enhanced the neuroinflammation and microglia activation in CLP mice. On the contrary, neutralizing anti-IL-17A or anti-IL-17R antibodies mitigated the CNS inflammation and microglia activation, thus alleviating the cognitive dysfunction. Furthermore, as compared to the sham control, microglia cultured from CLP mice produced significantly higher levels of cytokines and expressed with higher fluorescence intensity of Iba-1 in response to IL-17A or LPS. Pretreatment with anti-IL-17R ab suppressed the Iba-1 expression and cytokine production in microglia stimulated by IL-17A. In conclusion, blockade of the IL-17A/IL-17R pathway inhibited microglia activation and neuroinflammation, thereby partially reversing sepsis-induced cognitive impairment. The present study suggested that the IL-17A/IL-17R signaling pathway had an important, nonredundant role in the development of SAE.

Treatment of Recalcitrant Acrodermatitis Continua of Hallopeau With Brodalumab

To the Editor: Acrodermatitis continua of Hallopeau (ACH) is a relatively rare chronic disorder with clinical findings of pustules and erythematous plaques on the digits.1 Although it is a variant of pustular psoriasis, it can be resistant to multiple lines of therapy. We describe for the first time a patient with recalcitrant ACH successfully treated with brodalumab, an interleukin-17 receptor A (IL-17RA) blocking antibody.

Structural Insights into the Interleukin-17 Family Cytokines and Their Receptors.

The IL-17 family in humans consists of six distinct cytokines (IL-17A-F) that can interact with five IL-17 receptors (IL-17RA-E). The interaction between these cytokines and their receptors are critical in mediating host defenses while also making major contributions to inflammatory and autoimmune responses as demonstrated through both in vitro and in vivo experiments as well as human clinical trials. Inhibition of the IL-17A/IL-17RA interaction by monoclonal antibodies has also displayed remarkable efficacies in clinical trials against psoriasis and other autoimmune diseases. Recently, we and others reported the identification and characterization of both small-molecule and peptide IL-17A antagonists. These non-antibody IL-17A antagonists can effectively and selectively disrupt the IL-17A/IL-17RA complex and may provide alternative modalities to treat IL-17-related autoimmune and inflammatory diseases. This chapter summarizes the reported crystal structures of the IL-17 cytokines, their complexes with IL-17RA, and their complexes with both monoclonal antibodies as well as small-molecule and peptide antagonists.

Effects of interleukin-17A in nucleus pulposus cells and its small-molecule inhibitors for intervertebral disc disease.

Intervertebral discs (IVD) degeneration, which is caused by ageing or mechanical stress, leads to IVD disease, including back pain and sciatica. The cytokine interleukin (IL)-17A is elevated in NP cells during IVD disease. Here we explored the pharmacotherapeutic potential of IL-17A for the treatment of IVD disease using small-molecule inhibitors that block binding of IL-17A to the IL-17A receptor (IL-17RA). Treatment of NP cells with IL-17A increased expression of cyclooxygenase-2 (COX-2), IL-6, matrix metalloproteinase (MMP)-3 and MMP-13. These increases were suppressed by an IL-17A-neutralizing antibody, and small molecules that were identified as inhibitors by binding to the IL-17A-binding region of IL-17RA. IL-17A signalling also altered sulphated glycosaminoglycan deposition and spheroid colony formation, while treatment with small-molecule inhibitors of IL-17A attenuated this response. Furthermore, mitogen-activated protein kinase pathways were activated by IL-17A stimulation and induced IL-6 and COX-2 expression, while small-molecule inhibitors of IL-17A suppressed their expression. Taken together, these results show that IL-17A is a valid target for IVD disease therapy and that small-molecule inhibitors that inhibit the IL-17A-IL-17RA interaction may be useful for pharmacotherapy of IVD disease.

Phase 3 Studies Comparing Brodalumab with Ustekinumab in Psoriasis.

BACKGROUND: Early clinical studies suggested that the anti-interleukin-17 receptor A monoclonal antibody brodalumab has efficacy in the treatment of psoriasis. METHODS: In two phase 3 studies (AMAGINE-2 and AMAGINE-3), patients with moderate-to-severe psoriasis were randomly assigned to receive brodalumab (210 mg or 140 mg every 2 weeks), ustekinumab (45 mg for patients with a body weight ≤100 kg and 90 mg for patients >100 kg), or placebo. At week 12, patients receiving brodalumab were randomly assigned again to receive a brodalumab maintenance dose of 210 mg every 2 weeks or 140 mg every 2 weeks, every 4 weeks, or every 8 weeks; patients receiving ustekinumab continued to receive ustekinumab every 12 weeks, and patients receiving placebo received 210 mg of brodalumab every 2 weeks. The primary aims were to evaluate the superiority of brodalumab over placebo at week 12 with respect to at least a 75% reduction in the psoriasis area-and-severity index score (PASI 75) and a static physician's global assessment (sPGA) score of 0 or 1 (clear or almost clear skin), as well as the superiority of brodalumab over ustekinumab at week 12 with respect to a 100% reduction in PASI score (PASI 100). RESULTS: At week 12, the PASI 75 response rates were higher with brodalumab at the 210-mg and 140-mg doses than with placebo (86% and 67%, respectively, vs. 8% [AMAGINE-2] and 85% and 69%, respectively, vs. 6% [AMAGINE-3]; P<0.001); the rates of sPGA scores of 0 or 1 were also higher with brodalumab (P<0.001). The week 12 PASI 100 response rates were significantly higher with 210 mg of brodalumab than with ustekinumab (44% vs. 22% [AMAGINE-2] and 37% vs. 19% [AMAGINE-3], P<0.001). The PASI 100 response rates with 140 mg of brodalumab were 26% in AMAGINE-2 (P=0.08 for the comparison with ustekinumab) and 27% in AMAGINE-3 (P=0.007). Rates of neutropenia were higher with brodalumab and with ustekinumab than with placebo. Mild or moderate candida infections were more frequent with brodalumab than with ustekinumab or placebo. Through week 52, the rates of serious infectious episodes were 1.0 (AMAGINE-2) and 1.3 (AMAGINE-3) per 100 patient-years of exposure to brodalumab. CONCLUSIONS: Brodalumab treatment resulted in significant clinical improvements in patients with moderate-to-severe psoriasis. (Funded by Amgen; AMAGINE-2 and AMAGINE-3 ClinicalTrials.gov numbers, NCT01708603 and NCT01708629.).

ABD-Derived Protein Blockers of Human IL-17 Receptor A as Non-IgG Alternatives for Modulation of IL-17-Dependent Pro-Inflammatory Axis.

Interleukin 17 (IL-17) and its cognate receptor A (IL-17RA) play a crucial role in Th17 cells-mediated pro-inflammatory pathway and pathogenesis of several autoimmune disorders including psoriasis. IL-17 is mainly produced by activated Th-17 helper cells upon stimulation by IL-23 and, via binding to its receptors, mediates IL-17-driven cell signaling in keratinocytes. Hyper-proliferation of keratinocytes belongs to major clinical manifestations in psoriasis. To modulate IL-17-mediated inflammatory cascade, we generated a unique collection of IL-17RA-targeting protein binders that prevent from binding of human IL-17A cytokine to its cell-surface receptor. To this goal, we used a highly complex combinatorial library derived from scaffold of albumin-binding domain (ABD) of streptococcal protein G, and ribosome display selection, to yield a collection of ABD-derived high-affinity ligands of human IL-17RA, called ARS binders. From 67 analyzed ABD variants, 7 different sequence families were identified. Representatives of these groups competed with human IL-17A for binding to recombinant IL-17RA receptor as well as to IL-17RA-Immunoglobulin G chimera, as tested in enzyme-linked immunosorbent assay (ELISA). Five ARS variants bound to IL-17RA-expressing THP-1 cells and blocked binding of human IL-17 cytokine to the cell surface, as tested by flow cytometry. Three variants exhibited high-affinity binding with a nanomolar Kd value to human keratinocyte HaCaT cells, as measured using Ligand Tracer Green Line. Upon IL-17-stimulated activation, ARS variants inhibited secretion of Gro-α (CXCL1) by normal human skin fibroblasts in vitro. Thus, we identified a novel class of inhibitory ligands that might serve as immunosuppressive IL-17RA-targeted non-IgG protein antagonists.

Brodalumab, an anti-IL17RA monoclonal antibody, in psoriatic arthritis.

BACKGROUND: We assessed the efficacy and safety of brodalumab, a human monoclonal antibody against interleukin-17 receptor A (IL17RA), in a phase 2, randomized, double-blind, placebo-controlled study involving patients with psoriatic arthritis. METHODS: We randomly assigned patients with active psoriatic arthritis to receive brodalumab (140 or 280 mg subcutaneously) or placebo on day 1 and at weeks 1, 2, 4, 6, 8, and 10. At week 12, patients who had not discontinued their participation in the study were offered open-label brodalumab (280 mg) every 2 weeks. The primary end point was 20% improvement in American College of Rheumatology response criteria (ACR 20) at week 12. RESULTS: Of the 168 patients who underwent randomization (57 in the brodalumab 140-mg group, 56 in the brodalumab 280-mg group, and 55 in the placebo group), 159 completed the double-blind phase and 134 completed 40 weeks of the open-label extension. At week 12, the brodalumab 140-mg and 280-mg groups had higher rates of ACR 20 than the placebo group (37% [P=0.03] and 39% [P=0.02], respectively, vs. 18%); they also had higher rates of 50% improvement (ACR 50) (14% [P=0.05] and 14% [P=0.05] vs. 4%). Rates of 70% improvement were not significantly higher in the brodalumab groups. Similar degrees of improvement were noted among patients who had received previous biologic therapy and those who had not received such therapy. At week 24, ACR 20 response rates in the brodalumab 140-mg and 280-mg groups were 51% and 64%, respectively, as compared with 44% among patients who switched from placebo to open-label brodalumab; responses were sustained through week 52. At week 12, serious adverse events had occurred in 3% of patients in the brodalumab groups and in 2% of those in the placebo group. CONCLUSIONS: Brodalumab significantly improved response rates among patients with psoriatic arthritis. Larger studies of longer duration are necessary to assess adverse events. (Funded by Amgen; ClinicalTrials.gov number, NCT01516957 .).