Interleukin 6 targeting in refractory Takayasu arteritis: serial noninvasive imaging is mandatory to monitor efficacy

IS PET/MRI A RELIABLE TOOL FOR DETECTING VASCULAR ACTIVITY IN TREATED CHILDHOOD-ONSET TAKAYASU'S ARTERITIS (C-TA)? A MULTICENTER STUDY

OBJECTIVES

To assess whether 18F-fluordeoxiglucose-positron emission tomography/magnetic resonance imaging (18F-FDG-PET/MRI) with angiographic sequences can contribute to detecting vessel wall inflammation in patients with childhood-onset Takayasu's arteritis (c-TA) under immunosuppressive therapy.

METHODS

Three-centre cross-sectional study was conducted. 18F-FDG-PET/MRI scans were performed in c-TA patients and in oncologic patients, who served as the control group. Clinical and laboratorial characteristics were also analysed.

RESULTS

Seventeen c-TA patients (65% females) between the ages of 6 and 21 years, mean disease duration of 9.4 years were recruited. Only one patient presented clinical disease activity, and six (35.6%) had increased erythrocyte sedimentation rate (ESR) and/or C-reactive protein (CRP) levels. The most frequent magnetic resonance angiography (MRA) findings were stenosis and thickening, observed in 82.4% and 70.6% of c-TA patients, respectively. 18F-FDG-PET revealed 18F-FDG uptake higher than the liver in at least one arterial segment in 15 (88.2%) patients in a qualitative analysis and median standardized uptake value (SUVmax) of 3.22 (2.76-3.69) in a semi-quantitative analysis. c-TA patients presented significantly higher SUVmax than oncologic patients (p < 0.001). A positive correlation between SUVmax and CRP levels (Rho=0.528; p=0.029) was evidenced.

CONCLUSION

A state-of-the-art imaging modality was used in c-TA patients and revealed a strong arterial FDG uptake even in patients in apparent remission. We suppose that this finding may represent a silent activity in the vessel wall; however, we cannot exclude the possibility of arterial remodelling. Importantly, a negative imaging scan may help in immunosuppression withdrawal in daily clinical practice.

Novel Angiographic Scores for evaluation of Large Vessel Vasculitis

Arterial involvement is the cardinal feature of large-vessel vasculitis (LVV) and prevention of disease progression is the principal therapeutic goal. However, development of tools for its evaluation represents a major unmet need. To address this, a widely-applicable imaging tool for LVV, analysing arterial involvement in 17 arterial territories, has been developed and validated. Individual stenosis and dilation scores were generated and combined in a composite score. The methodology was validated cross-sectionally and longitudinally in 131 patients, 96 Takayasu arteritis (TA), 35 large-vessel giant-cell arteritis (LV-GCA). In total, 4420 arterial segments from 260 imaging studies were evaluated. The new scores allowed quantitative grading of LVV arterial involvement with high consistency, revealing inter-patient differences. TA had higher stenosis and composite scores and lower dilation scores than LV-GCA. Baseline stenotic and composite scores reflected arterial damage rather than disease-activity. Longitudinal changes in all three scores correlated with disease activity and mirrored arterial disease evolution, reflecting both progressive injury and lesion improvement. Increases ≥1 in any score were specific for arterial disease progression. The scores objectively quantify arterial involvement in LVV, providing precise definition of disease phenotype and evolution. We propose that they represent novel vascular outcome measures essential for future clinical trials.

Discrepancies between vascular and systemic inflammation in large vessel vasculitis: an important problem revisited

A lack of absolute correlation between systemic inflammation parameters and ongoing vascular disease activity is an important problem in some patients with large vessel vasculitis, especially Takayasu arteritis (TAK). Systemic and vascular wall inflammation in TAK are obviously interrelated, but sometimes they may act independently. There are clear discrepancies between these two types of inflammation, including cytokine patterns and responses to treatment. Vascular and systemic inflammation may also be discordant in two subgroups of giant cell arteritis. The first subgroup is mainly characterized by severe systemic inflammation mostly associated with IL-6-driven immunity, while in the second subgroup there is less systemic inflammation but prominent neuro-ophthalmic ischaemic complications characterized mostly by IFN-γ-mediated effects. Although no definite boundaries exist, it may be suggested that the IL-6/Th17/IL-17 pathway primarily drives systemic inflammation while the IL-12/Th1/IFN-γ pathway dominates in vascular wall inflammation both in TAK and giant cell arteritis. Immunosuppressive treatment of TAK (especially corticosteroids) initially suppresses systemic inflammation, while longer treatment duration is required for the suppression of vascular inflammation. Therefore, evaluating only the systemic inflammation may be misleading. Vascular wall inflammation is currently evaluated using expensive imaging methods, which are not feasible for repetitive use. Although pentraxin-3 is superior to erythrocyte sedimentation rate and CRP, we need more reliable biomarkers to reflect vascular wall inflammation in patients with TAK.

Biological treatments in giant cell arteritis & Takayasu arteritis

Giant cell arteritis (GCA) and Takayasu arteritis (TAK) are the two main large vessel vasculitides. They share some similarities regarding their clinical, radiological and histological presentations but some pathogenic processes in GCA and TAK are activated differently, thus explaining their different sensitivity to biological therapies. The treatment of GCA and TAK essentially relies on glucocorticoids. However, thanks to major progress in our understanding of their pathogenesis, the role of biological therapies in the treatment of these two vasculitides is expanding, especially in relapsing or refractory diseases. In this review, the efficacy, the safety and the limits of the main biological therapies ever tested in GCA and TAK are discussed. Briefly, anti TNF-α agents appear to be effective in treating TAK but not GCA. Recent randomized placebo-controlled trials have reported on the efficacy and safety of abatacept and mostly tocilizumab in inducing and maintaining remission of GCA. Abatacept was not effective in TAK and robust data are still lacking to draw any conclusions concerning the use of tocilizumab in TAK. Furthermore, ustekinumab appears promising in relapsing/refractory GCA whereas rituximab has been reported to be effective in only a few cases of refractory TAK patients. If a biological therapy is indicated, and in light of the data discussed in this review, the first choice would be tocilizumab in GCA and anti-TNF-α agents (mainly infliximab) in TAK.

What is new in management of Takayasu arteritis?

Management of Takayasu arteritis (TAK) is challenging mostly due to difficulties in assessing actual disease activity. The rational of medical treatment is to suppress both vascular and systemic inflammation with appropriate systemic immunosuppression, including corticosteroids and conventional immunosuppressive (IS) agents. In case of refractory disease activity, biologic agents such as TNF inhibitors and tocilizumab may be tried. In selected cases, endovascular interventions and surgical procedures may be indicated and should be performed during inactive disease. Among conventional IS agents, new data is available for leflunomide. On the other hand, most of the new information in the management of TAK arises from the growing experience with biologic agents used in resistant cases. Besides, there are potential new therapeutic targets which may be promising in the future for medical treatment of TAK. Finally, new trends in endovascular interventions for management of TAK deserve attention.

Application of imaging techniques for Takayasu arteritis

Arterial injury with subsequent remodelling and predisposition to arterial stenosis and/or dilation are the hallmarks of Takayasu arteritis. The degree of arterial damage closely aligns with prognosis and therefore its prevention is the predominant aim of therapy. Non-invasive imaging has greatly improved our ability to identify the extent and severity of disease and to monitor its progress. However, many questions remain concerning the optimal use of individual modalities at different stages of disease. Imaging methods for the quantification of arterial damage are lacking. Likewise, no single technique can accurately determine disease activity within the arterial wall or distinguish inflammatory and non-inflammatory disease progression. The aim of this review is to outline current imaging strategies in Takayasu arteritis, their individual roles in diagnosis and disease monitoring and potential future advances.

Chromogranin-A production and fragmentation in patients with Takayasu arteritis

BACKGROUND

Chromogranin-A (CgA) is a secretory protein processed into peptides that regulate angiogenesis and vascular cells activation, migration and proliferation. These processes may influence arterial inflammation and remodelling in Takayasu arteritis (TA).

METHODS

Plasma levels of full-length CgA (CgA439), CgA fragments lacking the C-terminal region (CgA-FRs) and the N-terminal fragment, CgA1-76 (vasostatin-1, VS-1) were analysed in 42 patients with TA and 20 healthy age-matched controls. Vascular remodelling was longitudinally assessed by imaging. CgA peptides were related to markers of systemic and local inflammation, disease activity and vascular remodelling.

RESULTS

Levels of CgA-FRs and VS-1 were increased in TA. Treatment with proton-pump inhibitors (PPIs) and arterial hypertension partially accounted for CgA levels and high inter-patient variability. CgA439, CgA-FRs and VS-1 levels did not reflect disease activity or extent. Markers of systemic or local inflammation correlated with higher CgA-FRs and VS-1 in normotensive patients and with higher CgA439 in hypertensive patients. Treatment with non-biologic anti-rheumatic agents was associated with increased CgA-FRs and a distinctive regulation of CgA processing. Reduced blood levels of anti-angiogenic CgA peptides were associated with vascular remodelling in the groups of patients on PPIs and with arterial hypertension.

CONCLUSIONS

The plasma levels of CgA fragments are markedly increased in TA as a consequence of disease- and therapy-related variables. Anti-angiogenic forms of CgA may limit vascular remodelling. Given the effect of the various CgA peptides, it is advisable to limit the therapeutic prescriptions that might influence CgA-derived peptide levels to clearly agreed medical indications until further data become available.

Outcome measures for Takayasu's arteritis

PURPOSE OF REVIEW

Takayasu's arteritis (TAK) is a large-vessel vasculitis with a chronic, indolent course affecting the aorta and its main branches. This review will describe the recent studies to develop validated outcome measures to assess TAK.

RECENT FINDINGS

TAK is traditionally assessed with a physician's global assessment including symptoms and signs of inflammation and vascular insufficiency, acute-phase reactants (APRs), and imaging including conventional digital subtraction angiography, computerized tomographic, and magnetic resonance angiography, and recently 18-FDG-PET. Recent attempts to develop a validated tool for disease assessment include the Indian Takayasu Clinical Activity Score (ITAS2010), which incorporates clinical signs and symptoms with APRs in a simplified and weighted adoption of the Birmingham Vasculitis Activity Score. Among biomarkers to assess clinical activity, pentraxin-3 is perhaps the most promising, but its validity and superiority against APRs in clinical practice need to be demonstrated. Patient-reported outcomes (PROs) are increasingly recognized as of substantial importance to measure in clinical trials; in addition to so-called 'generic' tools such as the SF-36 or measures of fatigue, disease-specific instruments would likely help capture aspects of TAK not measured by generic quality-of-life assessments or physician-based tools.

SUMMARY

Although outcome measures for TAK are not sufficiently validated, progress in the assessment of TAK is reflected in recent studies with new tools such as ITAS2010, new biomarkers, and a variety of PROs.

Systemic pentraxin-3 levels reflect vascular enhancement and progression in Takayasu arteritis

Introduction

Progression of arterial involvement is often observed in patients with Takayasu arteritis (TA) thought to be in remission. This reflects the failure of currently used biomarkers and activity criteria to detect smouldering inflammation occurring within arterial wall. Pentraxin-3 (PTX3) is a soluble pattern recognition receptor produced at sites of inflammation and could reveal systemic as well as localized inflammatory processes. We verified whether the blood concentrations of PTX3 and of C-reactive protein (CRP) in patients with Takayasu arteritis (TA) might reflect vascular wall involvement, as assessed by signal enhancement after contrast media administration, and the progression of arterial involvement.

Methods

A cross-sectional single-centre study was carried out on 42 patients with TA that comprised assessment of PTX3, of CRP and erythrocyte sedimentation velocity (ESR). In total, 20 healthy controls and 20 patients with Systemic Lupus Erythematous (SLE) served as controls. Vascular imaging was carried out by magnetic resonance angiography, doppler ultrasonography and computed tomography angiography.

Results

Patients with TA and SLE had higher plasmatic PTX3 and CRP concentrations than healthy controls (P = 0.009 and 0.017, respectively). PTX3 levels did not correlate with those of CRP. Patients with active systemic TA had significantly higher concentrations of CRP but similar levels of PTX3 than patients with quiescent disease. In contrast, patients with vascular inflammation detectable at imaging had higher PTX3 concentrations (P = 0.016) than those in which vessel inflammation was not evident, while CRP levels were similar. The concentration of PTX3 but not that of CRP was significantly higher in TA patients with worsening arterial lesions that were not receiving antagonists of tumor necrosis factor-α or interleukin-6.

Conclusions

Arterial inflammation and progression of vascular involvement influence plasma PTX3 levels in TA, while levels of CRP accurately reflect the burden of systemic inflammation. These results support the contention that PTX3 reflects different aspects of inflammation than CRP and might represent a biomarker of actual arteritis in TA.

Anti-cytokine treatment for Takayasu arteritis: State of the art

Takayasu arteritis (TA) is a rare and idiopathic large-vessel arteritis typically affecting young women which has important morbidity and mortality. There are no animal models of TA and pathogenesis is still mysterious. Clinical assessment lacks accurate activity indexes and is based on the integration of clinical, laboratory and radiological data. TA rarity has hampered randomized clinical trials and the achievement of high-quality evidence to guide clinical activity. Prevention of vascular progression, with progressive vessel wall remodelling and hyperplasia, is the main therapeutic goal. Medical therapy remains the mainstay of management and comprises traditional immunosuppressive agents and anti-inflammatory drugs, such as steroids and blockers of pivotal cytokines, TNF-α and IL-6. These strategies however only partially limit vascular progression, indicating that local molecular events are involved. Here we discuss recent data suggesting that selected cellular components of TA lesions should be evaluated as novel therapeutic targets.