IL-17 inhibition in axial spondyloarthritis: current and future perspectives

Association between serum interleukin-17 levels and ectopic bone formation in OPLL patients with DISH

OBJECTIVE

To investigate the relationship between the severity and morphology of heterotopic ossification in the spinal ligaments including sacroiliac (SI) joints, and serum interleukin-17 (IL-17) levels in patients with ossification of the posterior longitudinal ligament (OPLL) with or without diffuse idiopathic skeletal hyperostosis (DISH), as well as a non-OPLL group.

METHODS

A total of 103 patients with OPLL [DISH (-), n = 50; DISH (+), n = 53] and 53 age- and gender-matched controls were included. The serum levels of IL-17 were analysed, and the severity of ectopic ossification and the morphology of ectopic bone formation were evaluated. The SI joint morphological variations were categorized into four types.

RESULTS

No significant differences were found in serum IL-17 levels between the OPLL and control groups. However, the DISH (+) group showed higher IL-17 levels than the DISH (-) group, especially in female patients (P = 0.003). Additionally, IL-17 levels were positively correlated with the number of flat vertebral units, this being one of the characteristic DISH ossification types (R2 = 0.199, P = 0.012). IL-17 levels in the type showing bridging osteophyte and bone fusion were significantly higher in the DISH (+) group than in the DISH (-) group.

CONCLUSION

The morphological characteristics of paravertebral bone formation in the entire spine, including the SI joint, are likely associated with serum IL-17 levels in OPLL. These findings provide pathological and serological evidence of local inflammation contributing to paravertebral ossification of OPLL patients.

Identification of necroptosis-related genes in ankylosing spondylitis by bioinformatics and experimental validation

The pathogenesis of ankylosing spondylitis (AS) remains unclear, and while recent studies have implicated necroptosis in various autoimmune diseases, an investigation of its relationship with AS has not been reported. In this study, we utilized the Gene Expression Omnibus database to compare gene expressions between AS patients and healthy controls, identifying 18 differentially expressed necroptosis-related genes (DENRGs), with 8 upregulated and 10 downregulated. Through the application of three machine learning algorithms-least absolute shrinkage and selection operation, support vector machine-recursive feature elimination and random forest-two hub genes, FASLG and TARDBP, were pinpointed. These genes demonstrated high specificity and sensitivity for AS diagnosis, as evidenced by receiver operating characteristic curve analysis. These findings were further supported by external datasets and cellular experiments, which confirmed the downregulation of FASLG and upregulation of TARDBP in AS patients. Immune cell infiltration analysis suggested that CD4+ T cells, CD8+ T cells, NK cells and neutrophils may be associated with the development of AS. Notably, in the group with high FASLG expression, there was a significant infiltration of CD8+ T cells, memory-activated CD4+ T cells and resting NK cells, with relatively less infiltration of memory-resting CD4+ T cells and neutrophils. Conversely, in the group with high TARDBP expression, there was enhanced infiltration of naïve CD4+ T cells and M0 macrophages, with a reduced presence of memory-resting CD4+ T cells. In summary, FASLG and TARDBP may contribute to AS pathogenesis by regulating the immune microenvironment and immune-related signalling pathways. These findings offer new insights into the molecular mechanisms of AS and suggest potential new targets for therapeutic strategies.

Adherence to therapy of ixekizumab and secukinumab in psoriatic arthritis patients using first- or second-line IL-17A inhibitor treatment: a Danish population-based cohort study

OBJECTIVES

To assess the effectiveness and tolerability of first- and second-line interleukin (IL)-17A inhibitor treatment in PsA patients from 2014 to 2021 using data from the Danish Rheumatology Registry (DANBIO) by investigating adherence to therapy.

METHOD

PsA patients recorded in the DANBIO who received a first- or second-line IL-17A inhibitor treatment were included in this study. All patients included had previously received one or more TNF inhibitor treatment. Baseline characteristics were analysed in subgroups as first-line IL-17A inhibitor treatment and second-line IL-17A inhibitor treatment. Adherence to therapy of first- or second-line IL-17A inhibitor treatments was reported as Kaplan-Meier plots.

RESULTS

A total of 534 patients were included in the study, with 534 first-line switchers (secukinumab: 510, ixekizumab: 24) and 102 second-line switchers (secukinumab: 35, ixekizumab: 67). Baseline characteristics showed a similar HAQ and visual analogue scale (VAS) for pain. VAS global, 28-joint DAS with CRP and the previous number of biologic DMARD treatments were similar, with a greater value for second-line switchers. First-line ixekizumab-treated patients present a younger age, greater percentage of females, a lower disease duration and a lower CRP value. Concomitant MTX use was greater for the first-line secukinumab-treated patients. First- and second-line switchers had a similar adherence to therapy. Second-line secukinumab and second-line ixekizumab switchers showed a similar adherence to treatment.

CONCLUSION

PsA patients receiving first- or second-line IL-17A inhibitors showed homogeneous baseline characteristics and similar adherence to therapy. Treatment failure of the first IL-17A inhibitor treatment should not preclude a second-line IL-17A inhibitor treatment.

The role of ixekizumab in the treatment of nonradiographic axial spondyloarthritis

Nonradiographic axial spondyloarthritis (nr-axSpA) is a subtype of SpA with undeveloped definite radiographic sacroiliitis. Tumor necrosis factor inhibitors have demonstrated effectiveness in nr-axSpA patients who do not respond to first-line therapy. More recently, accumulated data from genetic, experimental, and clinical studies revealed that IL-17 is a key player in the pathogenesis of SpA, leading to development of new biologics directly inhibiting IL-17. Among them, ixekizumab is a high-affinity monoclonal antibody that selectively targets IL-17A and has exhibited significant efficacy and acceptable safety profiles in the treatment of nr-axSpA. The aim of this paper is to narratively review the recent insights of IL-17 in the pathogenesis of axSpA and discuss the effectiveness and safety of ixekizumab in treatment of nr-axSpA.

Interleukin-17-targeted treatment in patients with spondyloarthritis and associated cardiometabolic risk profile

Spondyloarthritis is a group of immune-mediated rheumatic disorders that significantly impact patients' physical function and quality of life. Patients with spondyloarthritis experience a greater prevalence of cardiometabolic disorders, such as obesity, hypertension, dyslipidemia and diabetes mellitus, and these comorbidities are associated with increased spondyloarthritis disease activity and risk of cardiovascular events. This narrative review summarizes the evidence for a physiological link between inflammatory status and cardiometabolic comorbidities in spondyloarthritis, as well as the impact of interleukin (IL)-17 blockade versus other molecular mechanisms in patients with cardiometabolic conditions. The IL-23/IL-17 axis plays a pivotal role in the pathophysiology of spondyloarthritis by promoting inflammation and tissue remodeling at the affected joints and entheses. The importance of the IL-23/IL-17 signaling cascade in underlying sub-clinical inflammation in common cardiometabolic disorders suggests the existence of shared pathways between these processes and spondyloarthritis pathophysiology. Thus, a bidirectional relationship exists between the effects of biologic drugs and patients' cardiometabolic profile, which must be considered during treatment decision making. Biologic therapy may induce changes in patients' cardiometabolic status and cardiometabolic conditions may conversely impact the clinical response to biologic therapy. Available evidence regarding the impact of IL-17 blockade with secukinumab on cardiometabolic parameters suggests this drug does not interfere with traditional cardiovascular risk markers and could be associated with a decreased risk of cardiovascular events. Additionally, the efficacy and retention rates of secukinumab do not appear to be negatively affected by obesity, with some studies reporting a positive impact on clinical outcomes, contrary to that described with other approaches, such as tumor necrosis factor blockade. In this article, we also review evidence for this bidirectional association with other treatments for spondyloarthritis. Current evidence suggests that IL-17-targeted therapy with secukinumab is highly effective in spondyloarthritis patients with cardiometabolic comorbidities and may provide additional cardiometabolic benefits.

Drug retention rate and predictive factors of drug survival for secukinumab in radiographic axial spondyloarthritis

The drug retention rate has been an important indicator for evaluating the treatment tolerance. Unfortunately, our knowledge of the secukinumab retention rate in radiographic axial spondyloarthritis (r-AxSpA) is limited. The objective of this study was to assess the retention rate of secukinumab and evaluate predictive factors of drug survival based on data from a real-life cohort. We retrospectively assessed 147 r-AxSpA patients between May 2018 and January 2020 from the HUR-BIO database. Secukinumab retention rates were analyzed using the Kaplan-Meier method and Cox proportional hazard model was used for predictors factors. The global retention rate of secukinumab was 55% at 12 months. r-AxSpA patients with obesity had a lower frequency of secukinumab discontinuation (29% vs. 50%, p = 0.013) in comparison r-AxSpA patients without obesity. In multivariate analysis, multiple TNFi usage had a higher risk of secukinumab discontinuation [HR 1.99 (1.09-3.62), p = 0.024]; on the other hand, obesity had a lower risk [HR 0.45 (0.27-0.90), p = 0.008]. Except for not using multiple TNFi, this real-life analysis showed for the first time that obesity is not an adverse risk factor for secukinumab drug retention in r-AxSpA. Secukinumab, which is an interleukin-17A inhibitor, could act via a different pathway than tumor necrosis factor inhibitors (TNFi). The identification of predictive factors such as obesity that may affect the individual drug selection may provide more appropriate biologic treatment strategies for r-AxSpA.

Nonsteroidal anti-inflammatory drug-sparing effect of secukinumab in patients with radiographic axial spondyloarthritis: 4-year results from the MEASURE 2, 3 and 4 phase III trials

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used to reduce pain and inflammation, and are considered the cornerstone of pharmacological intervention in patients with radiographic axial spondyloarthritis (r-axSpA); however, the long-term use of NSAIDs is debatable due to their restricted therapeutic potential and the risk of side effects and complications. Therefore, reduction in NSAID intake is desirable in r-axSpA patients. Here, we report the long-term NSAID-sparing effect of secukinumab over 4 years in patients with r-axSpA. This post hoc analysis pooled data from 3 secukinumab trials (MEASURE 2-4) for each secukinumab maintenance dose of 150 and 300 mg, regardless of the loading dose regimen being i.v. or s.c. NSAID intake was evaluated prospectively using the Assessment of SpondyloArthritis International Society (ASAS)-NSAID score. Patients with an ASAS-NSAID score > 0 at baseline were analysed. NSAID-sparing endpoints included the mean change in the ASAS-NSAID score, the proportion of patients achieving 50% reduction, and the proportion of patients with an ASAS-NSAID score < 10. Percentages of patients who achieved BASDAI ≤ 2 were also assessed. Overall, 562 patients were included in this pooled analysis (secukinumab: 150 mg, N = 467; 300 mg, N = 95). The mean ASAS-NSAID score decreased with time in both the secukinumab 150 mg and 300 mg dose groups. The proportion of patients who achieved 50% reduction in the ASAS-NSAID score and clinically meaningful reduction of ASAS-NSAID score < 10 increased with time in both dose groups and in both low and high NSAID intake patients. The percentage of patients with a clinically relevant improvement (BASDAI ≤ 2) was consistently higher in patients with an ASAS-NSAID score < 10 than in patients with an ASAS-NSAID score ≥ 10. Secukinumab provided sustained, long-term NSAID-sparing effects in patients with r-axSpA for up to 4 years of treatment, as measured using the ASAS-NSAID score. Trial registered at clinicaltrials.gov: NCT01649375 ( https://clinicaltrials.gov/ct2/show/NCT01649375 ); NCT02008916 ( https://clinicaltrials.gov/ct2/show/NCT02008916 ); NCT02159053 ( https://clinicaltrials.gov/ct2/show/NCT02159053 ).

Clinical Trials Supporting the Role of the IL-17/IL-23 Axis in Axial Spondyloarthritis

The term spondyloarthritis (SpA) encompasses a heterogeneous group of inflammatory musculoskeletal diseases with several common genetic background and clinical features, including the possible involvement of the axial skeleton with peripheral mono- or oligo- arthritis and frequently coexisting skin, eye and intestinal manifestations. When the sacroiliac joints or other parts of the spine or thoracic wall are predominantly affected at magnetic resonance or X-ray imaging with inflammatory back pain, the disease is classified as axial SpA and the therapeutic choices are significantly different compared to cases of peripheral arthritis. Moving from the narrow effectiveness and safety profiles of non-steroidal anti-inflammatory drugs, there has been a significant research effort aimed at identifying new treatments based on our better understanding of the pathogenesis of SpA. Indeed, in parallel with the solid data demonstrating that IL-17 and IL-23 are key cytokines in the development of enthesitis and spondylitis, monoclonal antibodies interfering with this pathway have been developed for the treatment of axial SpA. Furthermore, the IL-17/IL-23 axis is key to extra-articular manifestations such as inflammatory bowel disease, uveitis, and psoriasis which are frequent comorbidities of SpA. Currently available drugs act through these mechanisms recognizing IL-23 and targeting IL-17, such as secukinumab and ixekizumab. These therapeutic approaches are now envisioned in the international treatment recommendations for psoriatic arthritis with an axial phenotype as well as for ankylosing spondylitis (AS). We will provide herein a concise comprehensive overview of the clinical evidence supporting the use of these and other drugs acting on IL-23 and IL-17 in axial SpA.

Anti-IL-17 Agents in the Treatment of Axial Spondyloarthritis

Axial spondyloarthritis (axSpA) describes a group of chronic inflammatory rheumatic diseases primarily involving the axial skeleton. IL-17 is involved in the pathogenesis of numerous inflammatory diseases, including inflammatory arthritis. Until a few years ago, the only biological agents licensed for the treatment of axSpA and nr-axSpA were TNF inhibitors. However, as some patients did not respond to TNF inhibition or experienced secondary failure, the introduction of the first two IL-17 inhibitors (secukinumab [SEC] and ixekizumab [IXE]) has extended the treatment options, and there are now three others (bimekizumab, brodalumab and netakimab) in various stages of clinical development. The last ten years have seen the development of a number of therapeutic recommendations that aimed at improving the management of axSpA patients. The aim of this narrative review of the published literature concerning the role of IL-17 in the pathogenesis of SpA, and the role of IL-17 inhibitors in the treatment of axSpA, is to provide a comprehensive picture of the clinical efficacy and safety of the drugs themselves, and the treatment strategies recommended in the international guidelines.

Interleukin 17 antagonist netakimab is effective and safe in the new coronavirus infection (COVID-19)

Cytokine release syndrome is a serious complication of the new coronavirus infection (COVID-19). The aim of the study was to assess effectiveness and safety of the IL-17 antagonist nekatimab for its treatment. The retrospective study included COVID-19 patients with C-reactive protein levels >60 mg/L. Patients received either netakimab (group NET), IL-6 antagonist tocilizumab (group TOC) or no anti-cytokine treatment (group CON). Forty-four patients were enrolled in the NET group, 27 patients in the TOC group, and 47 patients in the CON group. Mortality was lower in the NET group than in TOC and CON groups (2.3% vs. 14.8% and 31.9%; p = 0.018 and p < 0.001). NET group patients required intensive care unit admission (6.8% vs. 25.9% and 46.3%; p = 0.025 and p < 0.001) and mechanical ventilation (4.6% vs. 22.2% and 31.9%; p = 0.022 and p = 0.002) less frequently than patients of the TOC and CON groups. After 7-10 days of anti-cytokine drug administration, a reduction in lung lesion volume (p = 0.016) and an increase in the proportion of patients who did not need oxygen support (p = 0.005) or stayed in prone position (p = 0.044) was observed in the NET group only group; C-reactive protein levels were the same in the TOC and NET groups (p = 0.136) and lower in the CON group (p < 0.001 and p = 0.005). IL-6 levels decreased in the NET group (p = 0.005) and did not change in the TOC group (p = 0.953). There was no difference in the incidence of side effects between groups. The IL-17 antagonist netakimab is effective and safe in the treatment of cytokine release syndrome in COVID-19.

Ixekizumab Improves Functioning and Health in the Treatment of Radiographic Axial Spondyloarthritis: Week 52 Results from 2 Pivotal Studies

Objective.

This study evaluated the effect of ixekizumab (IXE) on self-reported functioning and health in patients with radiographic axial spondyloarthritis (r-axSpA) who were either biological disease-modifying antirheumatic drug (bDMARD)–naïve or failed at least 1 tumor necrosis factor inhibitor (TNFi).

Methods.

In 2 multicenter, randomized, double-blind, placebo-controlled, and active-controlled (bDMARD-naïve only) trials, patients with r-axSpA were randomly assigned to receive 80 mg of IXE [every 2 weeks (Q2W) or every 4 weeks (Q4W)], placebo (PBO), or adalimumab (ADA; bDMARD-naïve only). After 16 weeks, patients who received PBO or ADA were rerandomized to receive IXE (Q2W or Q4W) up to Week 52. Functioning and health were measured by the generic 36-item Short Form Health Survey (SF-36) and the disease-specific Assessment of Spondyloarthritis international Society Health Index (ASAS HI). Societal health utility was assessed by the 5-level EuroQol-5 Dimension (EQ-5D-5L).

Results.

At Week 16, both doses of IXE in bDMARD-naïve and TNFi-experienced patients resulted in larger improvement in SF-36, ASAS HI, and EQ-5D-5L versus placebo. For SF-36, the largest improvements were seen for the domains of bodily pain, physical function, and role physical. A larger proportion of patients reaching improvement in ASAS HI ≥ 3 as well as an achievement of ASAS HI good health status was reported in patients treated with IXE. Improvements were maintained through Week 52.

Conclusion.

IXE significantly improved functioning and health as assessed by both generic and disease-specific measures, as well as societal health utility values in patients with r-axSpA, as measured by SF-36, ASAS HI, and EQ-5D-5L at Week 16, and improvements were sustained through 52 weeks.

Efficacy and safety of IL-17 inhibitors for the treatment of ankylosing spondylitis: a systematic review and meta-analysis

Objectives

To systematically assess the efficacy and safety of IL-17 inhibitors in patients with active ankylosing spondylitis.

Methods

A systematic review of the literature was performed for randomized controlled trials (RCTs) concerning IL-17 inhibitors in patients with ankylosing spondylitis. Meta-analyses were used to determine the efficacy and safety of the IL-17 inhibitors in the treatment of these patients. The primary endpoint was predefined as the proportion of patients with at least 20% improvement in the Assessment of Spondyloarthritis International Society (ASAS20) response criteria at week 16, and the secondary endpoint was defined as ASAS40 at week 16.

Results

Six phase III randomized, double-blind, placebo-controlled trials including 1733 patients (1153 patients received IL-17 inhibitors, including secukinumab or ixekizumab, whereas 580 patients received a placebo as comparators) were included. At week 16, the IL-17 inhibitor regimen produced a significant increase in the ASAS20 response rate (RR = 1.63, 95% CI 1.45 to 1.84, p = 0.00) and the secondary endpoint ASAS40 response rate (RR = 2.12, 95% CI 1.75 to 2.56, p = 0.00) versus those for the placebo. With respect to the safety profile, more treatment-emergent adverse events (RR = 1.11, 95% CI 1.01 to 1.22, p = 0.03) and non-severe infections (RR = 1.82, 95% CI 1.40 to 2.37, p < 0.001) were described after treatment with IL-17 inhibitors than after treatment with placebo, while no increased risk of other adverse events was indicated after IL-17 inhibitor therapy, including death, discontinuation due to adverse events, or serious adverse events.

Conclusions

IL-17 inhibitors produced favorable response rates but an increased risk of non-severe infections in the treatment of active ankylosing spondylitis.

miR-21 may Act as a Potential Mediator Between Inflammation and Abnormal Bone Formation in Ankylosing Spondylitis Based on TNF-α Concentration-Dependent Manner Through the JAK2/STAT3 Pathway

Objective:

To explore the role of microRNA (miR-21) in new bone formation in ankylosing spondylitis (AS) as mediated by different concentration of tumor necrosis factor-α (TNF-α).

Methods:

Fibroblasts isolated from the hips of patients with AS were induced to osteogenesis. These cells were then stimulated with varying concentrations of TNF-α. MicroRNA-21 expressions were evaluated using reverse transcription–polymerase chain reaction (RT-PCR) and osteogenesis was detected via Alizarin Red S (ARS) staining and measurement of alkaline phosphatase (ALP) activity. Relative expressions of p-STAT3, Nuclear STAT3, cytoplasm STAT3, Runx2, BMP2, osteopontin, osteocalcin, and LC3B in AS fibroblasts were measured after exposure to different concentrations of TNF-α. The STAT3-inhibiting small interfering RNA allowed further exploration on its impact on miR-21 and primary miR-21 expressions. A proteoglycan-induced arthritis (PGIA) Balb/c mouse model was established in order to monitor sacroiliac joint (SIJ) inflammation and subsequent damage through magnetic resonance image. Serum miR-21 and TNF-α expressions were evaluated using RT-PCR and enzyme-linked immunosorbent assay. At week 16, mice models were transfected intravenously with miR-21 overexpressing agomir and miR-21 inhibiting antagomir for 7 successive days. The rate of abnormal bone formation at SIJ was evaluated using microcomputed tomography and hematoxylin and eosin staining at week 24. Western blot analysis enabled quantification of STAT-3, JAK-2, and interleukin (IL)-17A expressions present in the SIJ.

Results:

The in vitro miR-21 expression and osteogenesis activity were noted to be augmented in the setting of low TNF-α concentrations (0.01-0.1 ng/mL) while they were depressed in settings with higher TNF-α concentrations (1-10 ng/mL). Samples with the most distinct ARS manifestation and ALP activity as well as the highest miR-21 expressions were those who received 0.1 ng/mL of TNF-α. Primary miR-21 was found to be notable raised by Si-STAT3, while the converse effect was seen in mature miR-21 expressions. Intravenous injection of exogenous miR-21 contributed to new bone formation and significantly elevated expressions of STAT3, JAK2, and IL-17 in PGIA mice.

Conclusions:

The results revealed that miR-21 may act as a potential mediator between new bone formation and inflammation in AS.

[Pathogenesis of spondylarthritis : Relevance for treatment]

Although the pathogenesis of spondylarthritis (SpA) has been the subject of intensive research in recent years, the consequences for treatment are relatively minor. Basic research studies indicated a potentially important role of the cytokines tumor necrosis factor (TNF) alpha and interleukin (IL)-17 for the pathogenesis of SpA but their outstanding role could then only be demonstrated by their inhibition in clinical studies, while other promising targets, such as IL‑23 and IL‑6 could not be shown to be relevant (at least against axial manifestations) in clinical studies. The intestinal microbiota probably plays an important role in the pathogenesis but not yet for the treatment of SpA. Ultimately, early effective and long-term suppression of inflammation is currently the best method to prevent ankylosis in the long run.

Current Unmet Needs in Spondyloarthritis

PURPOSE OF REVIEW

There was a substantial progress in the field of spondyloarthritis (SpA) in terms of understanding disease mechanisms, early diagnosis, and improved treatment. Nonetheless, several unresolved questions and unmet needs do remain.

RECENT FINDINGS

Although the diagnostic delay in axial SpA is decreasing, it remains one of the longest in rheumatology. Application of referral strategies, as well as correct application and interpretation of imaging finding in the clinical context, is the main key to early diagnosis of axial SpA. Tumor necrosis factor (TNF) alpha and interleukin (IL)-17 represent currently two major treatment targets in SpA, while other promising targets such as IL-23 or IL-6 failed in clinical trials. There is an unmet need for strategy trials to optimize and to individualize treatment in SpA. The role of Janus kinases and their blockade in SpA is still to be explored. TNF blockade showed efficacy in peripheral SpA, and other targets (IL-17 and IL-23) should be investigated in clinical trials. Early, effective, and long-term suppression of inflammation is currently the best method to prevent structural damage progression in the spine in axial SpA, while specific effects of IL-17 blockade and of nonsteroidal anti-inflammatory drugs on new bone formation are still being investigated. This review summarizes the recent advances in diagnosis and treatment of SpA and discusses the current unmet needs in the field.