Eosinophilic granulomatosis with polyangiitis (EGPA) is a systemic disorder characterized by peripheral eosinophilia, severe eosinophilic asthma, sinusitis, transient pulmonary infiltrates, and features of medium/small-vessel vasculitis. EGPA belongs to the group of anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitides, although only 30 to 40% of patients display ANCA positivity, which is mainly of myeloperoxidase (MPO) specificity. Particularly, ANCA-positive patients typically show vasculitic features. Interleukin (IL)-5 has been demonstrated to play a crucial role in determining eosinophilic airway inflammation in EGPA patients. Specifically, maturation, activation, and survival of eosinophils especially depend on IL-5 availability. Therefore, blocking IL-5 biological activity may be a rewarding strategy for control of eosinophilic inflammation. Several monoclonal antibodies with the ability to interfere with the biological activity of IL-5 have been developed, namely, mepolizumab, reslizumab, and benralizumab. Here, we discuss the role of these drugs in the management of severe eosinophilic asthma in the context of EGPA and report the outcome of two EGPA patients with severe eosinophilic asthma treated at our outpatient clinic.
1. Introduction
Eosinophilic granulomatosis with polyangiitis (EGPA, previously known as Churg–Strauss syndrome) belongs to the group of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides, which also include granulomatosis with polyangiitis (GPA), formerly known as Wegener’s granulomatosis, and microscopic polyangiitis (MPA)
[1,2][1][2]. In EGPA, ANCA specificity is mainly directed (~70% of cases) towards myeloperoxidase (MPO) and is typically associated with a perinuclear fluorescence pattern (p-ANCA) upon immunofluorescence staining of fixed neutrophils
[3]. However, rates of ANCA positivity in EGPA are lower than those reported in the other two conditions of the group (GPA and MPA), being around 30–40%
[1,2][1][2]. In addition, the clinical features of ANCA-positive patients significantly differ from those of ANCA-negative patients, with vasculitic involvement, in the form of glomerulonephritis, mononeuritis and/or alveolar hemorrhage, more frequent in the former, and cardiomyopathy more prevalent in the latter
[1,2,4][1][2][4]. According to the 2012 revised Chapel Hill Consensus Conference (CHCC) definition of vasculitides, EGPA is an eosinophil-rich and necrotizing granulomatous inflammation often involving the respiratory tract, with necrotizing vasculitis predominantly affecting small to medium vessels
[5,6][5][6] and is associated with asthma and eosinophilia. Since both vessel wall inflammation and eosinophilic infiltration are involved in the pathogenesis of organ damage, EGPA shares features of both systemic vasculitis and hypereosinophilic syndromes
[7]. Clinically, the course of EGPA follows a sequential pattern, with a prodromal phase characterized by late-onset asthma and other allergic-like features, an eosinophilic phase with blood and tissue eosinophilia, and, eventually, a vasculitic phase, dominated by purpura, mononeuritis, glomerulonephritis, and/or alveolitis
[1,2,8][1][2][8]. These phases may as well overlap. Patients may also complain of nonspecific constitutional symptoms, such as fever, fatigue, arthralgia, and weight loss. However, the time interval between onset of initial symptoms and the vasculitic phase may be rather long, thus delaying a correct diagnosis. More commonly, indeed, the onset of vasculitic manifestations (such as the appearance of mononeuritis multiplex, purpura, and glomerulonephritis), in a patient previously known to be affected by chronic rhinosinusitis, persistent moderate-to-severe asthma and eosinophilia, alerts the clinician to the diagnosis of EGPA
[9,10,11][9][10][11].
2. Therapeutic Management of EGPA
2.1. Standard Therapy
The cornerstone of therapy for EGPA remission induction is represented by glucocorticoids. Immunosuppressants are usually added to the glucocorticoid regimen, particularly in case of life-threatening organ involvement
[12], which may be assessed with the aid of the five factor score (FFS), a prognostic tool proposed in 1996
[13] and revised in 2011
[14] (
Table 1). FFS has been shown to be useful for survival prediction in EGPA; however, the original 1996 items have been refined in 2011 based on a better knowledge of the disease outcome
[13,14][13][14]. Using the original set of items (1996), mortality at 5 years was observed to be 11.9% in the absence of any prognostic factor; with 1 of the 5 factors present, mortality increased to 25.9%, while with 2 or more of the 5 factors present (FFS = 2, see explanation in
Table 1), mortality was shown to loom over 45.95% of the patients. In the 2011 update, age ≥ 65 years was also recognized as an independent predictor of poor prognosis, while visceral involvement was retained because it was still found to heavily weigh on the outcome. Conversely, ear, nose, and throat symptoms were associated with a lower relative risk of death. According to the 2011 set of criteria, mortality at 5 years was as follows: 9%, 21%, and 40% with FFS = 0, 1, and 2, respectively. Hence, the FFS may help identify patients requiring more aggressive treatment.
Table 1.
Comparison of 1996 and 2011 five factor score (FFS) items.
Original 1996 FFS |
Revised 2011 FFS |
Cardiac involvement Gastrointestinal disease (bleeding, perforation, infarction, or pancreatitis) Renal insufficiency (plasma creatinine concentration >1.6 mg/dL [141 mmol/L]) Proteinuria (>1 g/day) Central nervous system involvement |
Age > 65 years Cardiac insufficiency Renal insufficiency (stabilized peak creatinine 1.7 mg/dL [150 micromol/L]) Gastrointestinal involvement Absence of ENT manifestations (presence is associated with a better prognosis) |