Interleukin 6 inhibition in refractory antisynthetase syndrome: case-based literature review

Introduction: Antisynthetase syndrome (ASyS) is a rare idiopathic inflammatory myopathy (IIM), characterised by the presence of anti-aminoacyl tRNA synthetase antibodies. Significant clinical heterogeneity often results in delayed or missed diagnoses. While corticosteroids are the primary treatment for ASyS, immunosuppressants are frequently added as steroid-sparing agents. In cases where conventional therapies have limited efficacy, the use of biological disease-modifying anti-rheumatic drugs (bDMARDs) is increasingly being explored. Given the suggested role of interleukin 6 (IL-6) in the onset and progression of ASyS, its inhibition could be a potential therapeutic option. Nevertheless, the clinical effects of IL-6 blockade remain to be awaited, given the unpredictability of its anti- and pro-inflammatory effects. Off-label use of IL-6 antagonists has shown favourable results in selected cases with ASyS.