AB0718 Immune-apheresis in patients with inflammatory myopathies, a case series.

BackgroundIdiopathic inflammatory myopathies (IIM) comprise a heterogenous group of autoimmune diseases characterised by inflammation of muscle and affection of other organs, such as lung or skin. Some cases of IIM non-responsive to conventional treatment with glucocorticoids and DMARDs require treatment escalation. There are only limited data on efficacy and safety of immune-apheresis (IA) in IIM patients.ObjectivesThis retrospective cohort study aims to determine whether IA is effective in treating therapy-refractory IIM.MethodsPatients with active IIM undergoing IA (either plasma-exchange or immunoadsorption) at the Medical University Vienna were included in this explorative study. Patient characteristics and clinical data including serum levels of creatine kinase and concomitant medication were extracted from electronic medical records. As a primary endpoint, efficacy of IA was evaluated four weeks after initiation of IA, calculating absolute and relative change of CK-values as well as changes in steroid dose. Secondary endpoints included absolute and relative changes of CK-values at week 8 and week 12.ResultsFrom 2000 to 2021 25 IIM patients treated with IA were identified, 24 could be used for further analyses. Patient characteristics at start of IA are displayed in Table 1. Subtypes of IIM included dermatomyositis (DM 54.2%), polymyositis (PM 8.3%), Overlap-Myositis (20.8%), mmune-mediated-necrotising-myositis (IMNM 8.3 %), and antisynthetase syndrome (ASS 8.3 %). The majority of patients received concomitant steroid therapy (87.5 %) and DMARD therapy (62.5 %).Table 1.Cohort descriptives:Population, n (n= female%)24 (n=19;79.2 %)Age at Baseline (years; mean [SD];)42.5 [11.5]Subtyp Myositis (%,n)-Dermatomyositis54.2 % (13)-Polymyositis8.3 % (2)-Overlap-Myositis20.8 % (5)-Immune mediated necrotising myositis8.3 % (2)-Anti-Synthetase-Syndrom8.3 % (2)Immune Apharesis within 4 weeks (number of cycles)mean: 9.54,median: 9.5,[IQR: 8; 11.5]Previous DMARDs (%,n)-Any DMARDs-Mean number of previous DMARDs amongst all 24 patients62.5% (15)-Azathioprin33.3% (8)-Methotrexat45.8% (11)-Rituximab16.7% (4)-Mycophenolat mofetil16.7% (4)-Cyclophosphamid8.3% (2)-Ciclosporin8.3% (2)-(Hydroxy)-Chloroquin20.8% (5)-Etanercept4.2% (1)-Infliximab4.2% (1)Concomitant DMARDs (%,n)-Any DMARDs62.5% (15)-Azathioprin20.8% (5)-Methotrexat20.8% (5)-Rituximab4.2% (1)-Cyclophosphamid4.2% (1)-Ciclosporin4.2% (1)-(Hydroxy)-Chloroquin8.3% (2)Concomitant Steroids % (n)87.5% (21)-Dose prednisone at Baseline (mg/day; median [IQR])25 [12.5; 50] (21)-Dose prednisone at week 4 (mg/day; median [IQR]12.5 [0; 37.5] (22)CK-level at baseline (U/ml; median [IQR])970.5 [157.5; 3795.5]Change in CK-values from baselineAbsolute changeRelative change-to week 4 (n=24)median [IQR] U/ml% [IQR]-to week 8 (n=16)304.5 [28.8;2051]49.1 [22.4; 79.3] %-to week 12 (n=15)648.5 [25.8; 3939.3]70.0 [13.6; 87.7] %559 [-7; 3988]63.8 [-5.8; 98.1] %Until week 4 significant decrease in CK-values was observed in 21/24 patients (p<0.01; Figure 1), from median 970.5 [157.5; 3795.5] to 347[63; 1010] U/ml. Median [IQR] dose reduction of steroids was 12.5 [0; 12.5] mg/day absolute and 25% [0%, 100%] relative. No differences were observed within patients of different myositis subtypes. One patient died after 4 weeks, in 15 patients IA was maintained until week 12. Significant reduction in CK-values was observed from baseline to week 8 and 12 respectively (141 [78; 460], 111 [57;338]. Median and relative changes from baseline until week 12 are displayed in Table 1.Figure 1.Individual response in CK-levels from baseline to week 12ConclusionImmune-apheresis seems an effective therapeutic option in refractory IIM, leading to decrease of CK-values and steroid dose.References[1]Lundberg IE. Expert Perspective: Management of Refractory Inflammatory Myopathy. Arthritis Rheumatol. 2021 Aug;73(8):1394-1407.Disclosure of InterestsNone declared