OP0059 MAVRILIMUMAB (ANTI GM-CSF RECEPTOR Α MONOCLONAL ANTIBODY) REDUCES RISK OF FLARE AND INCREASES SUSTAINED REMISSION IN A PHASE 2 TRIAL OF PATIENTS WITH GIANT CELL ARTERITIS

Comparing treatment options for large vessel vasculitis

INTRODUCTION

Giant cell arteritis (GCA) and Takayasu arteritis (TAK) are the major forms of large vessel vasculitis (LVV).Glucocorticoids represent the cornerstone of LVV treatment, however, relapses and recurrences frequently occur when they are tapered or stopped, determining a prolonged exposure to glucocorticoids and a subsequent increased risk of glucocorticoid-related side effects. Therefore, conventional and biologic immunosuppressive drugs have been proposed to obtain a glucocorticoid-sparing effect.

AREAS COVERED

We searched PubMed® using the keywords "giant cell arteritis/drug therapy" and "Takayasu Arteritis/drug therapy" OR "Takayasu Arteritis/surgery". This review focuses on the management of LVV, based on the current evidence while highlighting the differences in terms of therapeutic management of TAK and GCA.

EXPERT OPINION

Conventional disease modifying anti-rheumatic drugs, such as methotrexate or azathioprine, are recommended in association to glucocorticoids for selected GCA and all TAK patients. Two randomized placebo-controlled trials recently demonstrated the efficacy of tocilizumab in reducing relapses and cumulative prednisone dosage in GCA patients with newly diagnosed or relapsing disease. Observational evidence and two small randomized controlled trials support the use of TNF-alpha inhibitors and tocilizumab as glucocorticoid-sparing agents in relapsing TAK, albeit high-quality evidence regarding the management of TAK is still lacking.

Looking ahead: giant-cell arteritis in 10 years time

Although great improvements have been achieved in the fields of diagnosing and treating patients with giant-cell arteritis (GCA) in the last decades, several questions remain unanswered. The progressive increase in the number of older people, together with growing awareness of the disease and use of advanced diagnostic tools by healthcare professionals, foretells a possible increase in both prevalence and number of newly diagnosed patients with GCA in the coming years. A thorough clarification of pathogenetic mechanisms and a better definition of clinical subsets are the first steps toward a better understanding of the disease and, subsequently, toward a better use of existing and future therapeutic options. Examination of the role of different imaging techniques for GCA diagnosing and monitoring, optimization, and personalization of glucocorticoids and other immunosuppressive agents, further development and introduction of novel drugs, identification of prognostic factors for long-term outcomes and management of treatment discontinuation will be the central topics of the research agenda in years to come.

Baricitinib for relapsing giant cell arteritis: a prospective open-label 52-week pilot study

BACKGROUND/PURPOSE

Preclinical vascular inflammation models have demonstrated effective suppression of arterial wall lesional T cells through inhibition of Janus kinase 3 and JAK1. However, JAK inhibition in patients with giant cell arteritis (GCA) has not been prospectively investigated.

METHODS

We performed a prospective, open-label, pilot study of baricitinib (4 mg/day) with a tiered glucocorticoid (GC) entry and accelerated taper in patients with relapsing GCA.

RESULTS

15 patients were enrolled (11, 73% female) with a mean age at entry of 72.4 (SD 7.2) years, median duration of GCA of 9 (IQR 7-21) months and median of 1 (1-2) prior relapse. Four (27%) patients entered the study on prednisone 30 mg/day, 6 (40%) at 20 mg/day and 5 (33%) at 10 mg/day. Fourteen patients completed 52 weeks of baricitinib. At week 52, 14/15 (93%) patients had ≥1 adverse event (AE) with the most frequent events, including infection not requiring antibiotics (n=8), infection requiring antibiotics (n=5), nausea (n=6), leg swelling (n=2), fatigue (n=2) and diarrhoea (n=1). One subject required baricitinib discontinuation due to AE. One serious adverse event was recorded. Only 1 of 14 (7%) patients relapsed during the study. The remaining 13 patients achieved steroid discontinuation and remained in disease remission during the 52-week study duration.

CONCLUSION

In this proof-of-concept study, baricitinib at 4 mg/day was well tolerated and discontinuation of GC was allowed in most patients with relapsing GCA. Larger randomised clinical trials are needed to determine the utility of JAK inhibition in GCA.

TRIAL REGISTRATION NUMBER

NCT03026504.

Need and value of targeted immunosuppressive therapy in giant cell arteritis

Despite the heterogeneity of the giant cell arteritis (GCA) at the level of clinical manifestations and the cellular and molecular players involved in its pathogenesis, GCA is still treated with standardised regimens largely based on glucocorticoids (GC). Long-term use of high dosages of GC as required in GCA are associated with many clinically relevant side effects. In the recent years, the interleukin-6 receptor blocker tocilizumab has become available as the only registered targeted immunosuppressive agent in GCA. However, immunological heterogeneity may require different pathways to be targeted in order to achieve a clinical, immunological and vascular remission in GCA. The advances in the targeted blockade of various molecular pathways involved in other inflammatory and autoimmune diseases have catalyzed the research on targeted therapy in GCA. This article gives an overview of the studies with targeted immunosuppressive treatments in GCA, with a focus on their clinical value, including their effects at the level of vascular inflammation.

[Biologics for connective tissue diseases and vasculitides]

Despite therapy with glucocorticoids (GC) and conventional immunosuppressants, patients with connective tissue diseases and vasculitides often develop functionally relevant and prognostically unfavourable internal organ damage. Based on new pathogenetic insights, biologics and small molecules have recently been studied as targeted therapies for collagen vascular diseases and vasculitides. The B lymphocyte stimulator antagonist belimumab has been used for the treatment of systemic lupus erythematosus (SLE) for several years and has recently also been approved as an add-on therapy for lupus nephritis. Anifrolumab, an antibody against the type‑1 interferon receptor, has also been shown to be effective in phase III trials for the treatment of SLE. The interleukin (IL)-6-antagonist tocilizumab showed efficacy in the treatment of interstitial lung disease (ILD) in systemic sclerosis (SSc) and thus has been approved in the USA, although the phase III trial had a negative primary endpoint. In Europe the tyrosine inhibitor nintedanib is approved for progressive ILD in SSc. Tocilizumab is approved for the treatment of giant cell arteritis and reduces both the risk of recurrence and the cumulative GC requirement. The B‑lymphocyte depleting antibody rituximab is approved for induction and maintenance therapy of granulomatosis with polyangiitis and microscopic polyangiitis (MPA) and is currently also being investigated for the treatment of eosinophilic granulomatosis with polyangiitis (EGPA). In patients with EGPA, the IL‑5 antibody mepolizumab leads to improved disease control and reduces GC requirements. A phase III trial of the small molecule antagonist avacopan targeting the complement C5a receptor as a replacement for high-dose GC in induction therapy of GPA and MPA met its primary endpoints. Various other biologics and small molecule antagonists are currently in clinical development for several type of vasculitis and collagen vascular diseases, some of them at advanced stages.

Temporal Artery Vascular Diseases

In the presence of temporal arteritis, clinicians often refer to the diagnosis of giant cell arteritis (GCA). However, differential diagnoses should also be evoked because other types of vascular diseases, vasculitis or not, may affect the temporal artery. Among vasculitis, Anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis is probably the most common, and typically affects the peri-adventitial small vessel of the temporal artery and sometimes mimics giant cell arteritis, however, other symptoms are frequently associated and more specific of ANCA-associated vasculitis prompt a search for ANCA. The Immunoglobulin G4-related disease (IgG4-RD) can cause temporal arteritis as well. Some infections can also affect the temporal artery, primarily an infection caused by the varicella-zoster virus (VZV), which has an arterial tropism that may play a role in triggering giant cell arteritis. Drugs, mainly checkpoint inhibitors that are used to treat cancer, can also trigger giant cell arteritis. Furthermore, the temporal artery can be affected by diseases other than vasculitis such as atherosclerosis, calcyphilaxis, aneurysm, or arteriovenous fistula. In this review, these different diseases affecting the temporal artery are described.

Functionally Heterogenous Macrophage Subsets in the Pathogenesis of Giant Cell Arteritis: Novel Targets for Disease Monitoring and Treatment

Giant cell arteritis (GCA) is a granulomatous large-vessel vasculitis that affects adults above 50 years of age. In GCA, circulating monocytes are recruited to the inflamed arteries. With cues from the vascular microenvironment, they differentiate into macrophages and play important roles in the pathogenesis of GCA via pro-inflammatory cytokine production and vascular remodeling. However, a deeper understanding of macrophage heterogeneity in GCA pathogenesis is needed to assist the development of novel diagnostic tools and targeted therapies. Here, we review the current knowledge on macrophage heterogeneity and diverse functions of macrophage subsets in the pathogenesis of GCA. We next discuss the possibility to exploit their heterogeneity as a source of novel biomarkers and as targets for nuclear imaging. Finally, we discuss novel macrophage-targeted therapies and future directions for targeting these cells in GCA.