Immunoadsorption as a novel therapy for refractory idiopathic inflammatory myopathies—a retrospective observational study

Objective Idiopathic inflammatory myopathies (IIM) are autoimmune disorders characterised by muscle inflammation, high creatine kinase (CK) levels, and disability. Despite immunomodulating therapies, patients often experience progressive disease, resulting in refractory conditions or dependence on glucocorticoids (GC). This study addresses the efficacy and safety of immunoadsorption (IAS) in refractory IIM. Methods A retrospective, monocentric study was conducted on patients with highly active IIM subjected to IAS between January 2000 and September 2021. Inclusion criteria were adult patients with confirmed IIM unresponsive to standard therapies, including GC and at least one disease-modifying antirheumatic drug. Primary end point was defined as minor improvement, requiring a ≥ 20% reduction in both daily GC-dosage and CK-levels at week 12, alongside patient comparative self-assessment (PCSA) rated as “no change” or “better.” Secondary endpoints included moderate (≥ 40%) and major (≥ 60%) improvements at weeks 4, 8, and 12. Relapse rates were assessed over a 3-month period following the last IAS procedure. Results The study included 23 refractory IIM patients treated with IAS. Primary end point was reached by 52.2% (n = 12) patients. Moderate improvement was observed in 8.7% (n = 2), 26.1% (n = 6), and 34.8% (n = 8) and major improvement in 8.7% (n = 2), 17.4% (n = 4), and 30.4% (n = 7) at weeks 4, 8, and 12, respectively. No unexpected adverse events were reported, with low relapse rates within 3 months post-IAS (18%). Conclusion IAS may be an effective adjunctive therapy in patients refractory to GC and conventional treatments, leading to rapid CK level reductions, decreased GC usage, and improvements in PCSA and muscle function.