Case reportMaintenance treatment with subcutaneous immunoglobulins in the long-term management of anti-HMCGR myopathy
Introduction
Anti-3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (HMGCR) myopathy is a rare, disabling, auto-immune myopathy with necrotizing pathological features, that usually follows statin exposure. Generally, patients present with proximal muscle weakness, elevated CK levels and high titres of antibodies against HMGCR [1] that persist despite statins discontinuation, while improvement typically follows the start of immunotherapy [2].
Even if different therapeutic strategies might be beneficial [3], no straightforward guidelines for the therapy of HMGCR have been outlined and it is very common to treat patients affected by anti-HMGCR myopathy with corticosteroids combined with intravenous immunoglobulin (IVIg) and a steroid sparing immunosuppressant [4], [5], [6]. In patients with contraindications to steroids, high dose IVIg have been also used successfully in monotherapy [7].
Subcutaneous Immunoglobulins (SCIg), initially applied as replacement therapy in patients with primary immunodeficiencies [8], represent an available alternative to long-term IVIg in several autoimmune neuromuscular disorders. In more recent years, the use of SCIg has been described in chronic inflammatory demyelinating neuropathy (CIDP), multifocal motor neuropathy (MMN), in some idiopathic inflammatory myopathies (IIM) and in Myasthenia Gravis [9], [10], [11], [12]. The many advantages of SCIg over IVIg include the lower rate of systemic adverse effects related to rapid peak of Ig serum, the lack of need for vascular accesses and the possibility of home self-administration [13]. The usefulness of SCIg in inflammatory myopathies has been previously reported for dermatomyositis (DM), polymyositis (PM) [14], [15], [16], in few cases of inclusion body myositis (IBM) and in myositis associated with connective tissue diseases [17].
At present, no data are available regarding SCIg in patients with anti-HMGCR myopathy.
Therefore, we report our experience in three patients affected by anti-HMGCR myopathy, in which SCIg contributed to obtain a stable remission.
Section snippets
Methods
We retrospectively analysed clinical records of patients affected by immune-mediated necrotizing anti-HMGCR myopathies treated with SCIg from 2018 to 2020 and followed in the outpatient clinic for neuromuscular disorders of IRCCS Ospedale Policlinico San Martino, Genova, Italy.
Patients underwent a complete neurological examination including the assessment of strength in six muscle groups (shoulder abduction, elbow flexion, wrist extension, hip flexion, knee extension, and ankle dorsiflexion) on
Results
Three patients (2 males, 1 female; mean age 66.3 years; range 59–77 years) have been studied, all affected by hypercholesterolemia, and treated with atorvastatin 20 mg/day (mean of 36.5 months; range 11–85.5 months) with no previous muscle symptoms. Comorbidities included hypertension in all patients, diabetes mellitus type 2 in two of them and psoriasis in one.
All patients presented subacute proximal weakness, mainly involving the lower limbs, with difficulties climbing stairs and standing
Discussion
Anti-HMGCR myopathy is a rare [19], but severe necrotizing myositis that require prompt identification and aggressive treatment to arrest the auto-immune mediated attack mainly to limb girdle muscles.
To our knowledge this is the first study analysing the long term SCIg therapy in a case series of anti-HMGCR myopathies. SCIg therapy was successfully used in the maintenance treatment of anti-HMGCR myopathy, in combination with oral steroids and a low dose of methotrexate (patient 1, patient 3).
Declaration of Competing Interest
None.
Funding source
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
References (22)
- et al.
Immune-mediated necrotizing myopathies working group. 224th ENMC international workshop: clinico-sero-pathological classification of immune-mediated necrotizing myopathies Zandvoort, The Netherlands, 14-16 October 2016
Neuromuscul Disord
(2018) Subcutaneous immunoglobulin replacement in primary immunodeficiencies
Clin Immunol
(2004)- et al.
Long-term subcutaneous immunoglobulin use in inflammatory myopathies: a retrospective review of 19 cases
Autoimmun Rev
(2016) - et al.
Subcutaneous IgG in immune-mediate diseases: proposed mechanisms of action and literature review
Autoimmun Rev
(2014) - et al.
Anti-HMGCR antibodies as a biomarker for immune-mediated necrotizing myopathies: a history of statins and experience from a large international multi-center study
Autoimmun Rev
(2016) - et al.
Critical review of the role of intravenous immunoglobulins in idiopathic inflammatory myopathies
Semin Arthritis Rheum
(2017 Feb) - et al.
Pathogenic role of anti-signal recognition protein and anti-3-Hydroxy-3-methylglutaryl-CoA reductase antibodies in necrotizing myopathies: Myofiber atrophy and impairment of muscle regeneration in necrotizing autoimmune myopathies
Ann Neurol
(2017) - et al.
Statin-induced anti-HMGCR myopathy: successful therapeutic strategies for corticosteroid-free remission in 55 patients
Arthritis Res Ther
(2020) - et al.
Clinical features and treatment outcomes of necrotizing autoimmune myopathy
JAMA Neurol
(2015) - et al.
Anti-HMGCR myopathy
J Neuromuscul Dis
(2018)