The effect of anakinra, an IL1 receptor antagonist, in patients with sporadic inclusion body myositis (sIBM): a small pilot study

Abstract

In sIBM, an inflammatory process mediated by cytotoxic T cells and cytokines in conjunction with a degenerative process, deposits of beta amyloid and misfolded proteins appear to be the main culprits in disease pathogenesis. IL-1β may play a key role because it is upregulated in sIBM myofibers, co-localizes with Amyloid Precursor Protein (APP) and promotes the production of APP and amyloid deposits. We performed a small, pilot study to examine whether anakinra, an IL1 receptor antagonist could benefit sIBM patients. Four patients with biopsy-proven sIBM received anakinra for a mean period of 7.7 months. No improvement in muscle strength or stabilization was noted in any of the patients based on grip strength and MRC measurements. The treatment failure may be due to insufficiency of anakinra to suppress the intramuscular IL1, the short study period, or the irrelevance of IL1 in the disease process.

Keywords: Autoimmunity; Cytotoxic T-cells; IL1 receptor; Inclusion body myositis; Inflammatory cytokines; anakinra.