Large Vessel Vasculitis

Large vessel vasculitis (LVV) is an autoimmune inflammatory disorder affecting the major arteries of the body. The diagnosis and monitoring this condition can be challenging, as patients often present with symptoms that are unclear, and the diagnostic criteria currently used are varied. Accurate diagnosis is essential because it helps to tailor the treatment to each patient. Some treatments, such as steroids and immunosuppressive medications, can have significant side effects, so they need to be used carefully and only when truly needed. An \[18F\]FDG Positron Emission Tomography/Computed Tomography (PET/CT) involves the injection of a small amount of radiolabelled sugar, which assesses glucose metabolism within the body. \[18F\]FDG PET/CT is already used by the NHS to detect inflammation within the vessel walls and diagnose LVV. Current diagnostic criteria for LVV largely rely on visual assessment by a radiologist. This approach therefore has limitations and may not fully capture changes in the levels of inflammation over time. A new generation of scanners, known as Long Axial Field-of-View (LAFOV)-PET/CT or Total Body PET, are currently transforming what is possible in the field of medical imaging. These LAFOV-PET/CT scanners have new digital detectors that are more sensitive, produce sharper images, and can scan the entire body rapidly. This offers several potential advantages for patients with LVV, including the clearer detection of vessel wall inflammation, the ability to administer lower doses of the radiolabelled sugar (\[18F\]FDG), and the ability to take repeated pictures over time to measure subtle changes in blood flow and inflammation. Patients receiving a routine NHS \[18F\]FDG PET/CT scan for LVV are typically scanned 60 minutes after injection of the radiotracer using a standard PET/CT. Another benefit of LAFOV-PET/CT scanners is their ability to assess the amount of the radiolabelled sugar taken up by the whole body almost as soon as it is injected which could give important additional information. As part of the LAVA-FLOW study we are planning to combine LAFOV-PET/CT with a CT Angiogram (CTA) in patients with LVV. A CTA is a scan that shows doctors what your blood vessels look like. It involves the injection of a dye into a vein that makes your blood vessels visible, highlighting vessel wall inflammation and vessel wall narrowing. This combination of LAFOV-PET/CT and CTA therefore has the potential to give a much more detailed picture of LVV than is achievable using current methods. The LAVA-FLOW study therefore aims to develop a standardised protocol to be used in different hospital centres across the UK for the imaging of LVV using LAFOV-PET/CT. We also hope that the results of this particular study could lead to further larger studies with the potential to update the diagnostic criteria and improve the monitoring of this condition.

Takayasu's arteritis (TAK) is a large vessel vasculitis preferentially affecting the aorta and its main branches, leading to wall vessels thickening, fibrosis, stenosis, and occlusion. Patients with TAK have a high morbidity rate, 50% will relapse and experience a vascular complication within 10 years from diagnosis. TAK inflammation is mediated by T cells and macrophages. Pro-inflammatory Th1 and Th17 cells are dominant infiltrates in the vascular walls, producing IFN-γ and IL-17 to drive the systemic and vascular manifestations of TAK. Currently, TAK patients are principally treated with non-specific steroids, which are associated with potential side effects, especially when used for a long-time course. Steroid treatment preferentially target innate cytokines, such as IL-1β, IL-12, and IL-6 but have little effect on tissue-residing T cells. Novel approach needs to eliminate all T-cell effectors. The use of classical immunosuppressive drugs (IS) (methotrexate, Leflunomide) and biotherapies are prescribed earlier in the management of the disease in order to improve remission, spare corticosteroids and reduce relapses. Data from observational series report remission in 37-76% of cases with anti TNF alpha and 68% with Tocilizumab. However, a placebo-controlled trial failed to show superiority of tocilizumab in TAK. To date, no immunomodulatory treatment has been approved for the management of TAK and corticosteroids sparing remains a major challenge in this disease. Our team has demonstrated the key role of Th1 and Th17 responses in the pathophysiology of TAK. We found that Th17 and Th1 pathways contribute to the systemic and vascular manifestations of TAK and glucocorticoid treatment suppresses Th1 cytokines but spares Th17 cytokines in patients with TAK. Other teams further confirmed the significant increase in Th17 axis in TAK, and its correlation with disease activity, clinical relapse and arterial fibrosis. Secukinumab is a fully human monoclonal antibody that selectively inhibits IL-17A. Secukinumab received approval for adult treatment of moderate to severe plaque psoriasis, active psoriatic arthritis, active non-radiographic axial spondyloarthritis, and active ankylosing spondylitis in numerous countries, including the EU and the USA Recently, a phase II clinical trial assessing the efficacy and safety of secukinumab vs placebo in combination with glucocorticoid taper regimen in giant cell arteritis showed that patients with active giant cell arteritis had a higher sustained remission rate in the secukinumab group than in the placebo group at week 28, and is now being studied in a phase 3 study (NCT04930094).Secukinumab was well tolerated with no new safety concerns. In TAK, recent observational data suggested that secukinumab might be an effective alternative to TNFi in severe TAK patients. Inhibition of IL-17A could represent a potential new therapeutic option for the treatment of severe TAK disease, hence the need for a prospective study to evaluate secukinumab in the management of active severe TAK.

Large vessel vasculitis (LVV) is a disease that causes damage to blood vessels. This damage to blood vessels can increase the risk of patients with LVV developing cardiovascular disease, including heart attacks and strokes. A chemical produced in the body called endothelin may contribute to this increase in cardiovascular disease risk by causing the vessels to stiffen and blood pressure to increase. It has previously been shown that by blocking the effects of endothelin, vessel stiffness and blood pressure improve. Bosentan is a tablet that blocks the effects of endothelin. Dapagliflozin is a sodium-glucose co-transporter 2 inhibitor that has been shown to improve blood vessel function and stiffness in patients with diabetes. The investigators plan to assess blood vessel function in those with LVV and participants without LVV. Participants with LVV will be given Bosentan and Dapagliflozin for 6 weeks, followed by Dapagliflozin for 4 weeks, to evaluate their impact on blood vessel function.

Large vessel vasculitis (LVV) causes vascular inflammation, leading to serious complications such as aneurysm formation and stroke. It is difficult to identify the inflammation of the vessel wall by the current imaging methods, thus affecting the timing of treatment and selection of treatment options. Improved examination methods to determine disease activity are highly needed to guide treatment.