Abstract
Statin-associated autoimmune myopathy is a rare muscle disorder, characterized by autoantibodies against HMGCR. The anti-HMGCR myopathy persists after statin, and often requires immunosuppressive therapy. However, there is not a standardized therapeutic approach. The purpose of this study is to report the effectiveness of the immunosuppressive treatment employed in a multi-center and multi-disciplinary cohort of patients affected by anti-HMGCR myopathy, in which an immunoglobulin (IVIG)-based treatment strategy was applied. We collected 16 consecutive patients with a diagnosis of anti-HMGCR myopathy, between 2012 and 2019, and recorded data on clinical and laboratory presentation (i.e., muscle strength, serum CK levels, and anti-HMGCR antibody titer) and treatment strategies. Our results highlight the safety and efficacy of an induction therapy combining IVIG with GCs and/or methotrexate to achieve persistent remission of the disease and steroid-free maintenance. Under IVIG-based regimens, clinical improvement and CK normalization occurred in more than two thirds of patients by six months. Relapse rate was low (3/16) and 2/3 relapses occurred after treatment suspension. Nearly 90% of the patients who successfully discontinued GCs were treated with a triple immunosuppressive regimen. In conclusion, an IVIG-based regimen, which particularly includes high-dose immunoglobulin, GCs and methotrexate, can provide a fast remission achievement with GC saving.
Highlights
Statin-associated autoimmune myopathy is a relatively newly described disorder and the presence of autoantibodies against 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) have only recently been identified [1,2]
The myopathy is characterized by symmetric muscle weakness, markedly elevated serum creatine kinase (CK) levels, abnormal electromyography (EMG) [9], and histologic evidence of muscle cell necrosis and degeneration, along with a lack of significant inflammatory infiltrates and circulating autoantibodies against 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) [7,10], which have been recognized as possible pathogenic autoantibodies [10,11]
There are no guidelines for therapy, to date; some studies suggest that high-dose intravenous immunoglobulins (IVIG) could be a promising therapy, consistently with their efficacy in other autoimmune myositis [15], while glucocorticoids (GCs) may not be the cornerstone of this disease, differently from polymyositis [13]
Summary
Statin-associated autoimmune myopathy is a relatively newly described disorder and the presence of autoantibodies against 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) have only recently been identified [1,2]. Its incidence is not well defined, though it is estimated in approximately 2–3 of every 100,000 statin-treated patients [6,7] It usually affects middle-aged people with some cardiovascular risk factors, such as type 2 diabetes, hypertension or hypercholesterolemia, which justify the introduction of statins [8]. A predisposing genetic background has been documented, since anti-HMGCR myopathy has one of the strongest associations between an immunogenetic risk factor and autoimmune disease, in particular with the class II human leukocyte antigen (HLA) allele D related B (DRB)1*11:01 [12]. There are no guidelines for therapy, to date; some studies suggest that high-dose intravenous immunoglobulins (IVIG) could be a promising therapy, consistently with their efficacy in other autoimmune myositis [15], while glucocorticoids (GCs) may not be the cornerstone of this disease, differently from polymyositis [13]
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