Background/Purpose: Dermatomyositis (DM), and particularly the subtype clinically amyopathic DM (CADM), is often associated with fatal rapidly progressive interstitial lung disease (RP-ILD) when anti-melanoma differentiation-associated gene 5 (MDA5) antibody is present, especially in Eastern Asian populations. There is no evidence-based strategy for treating this disease, but intensive treatment with high-dose corticosteroid and multiple immunosuppressants may be effective. However, RP-ILD often fails to respond to such intensive treatment regimens, and still has a very poor prognosis. Here, we report the efficacy of early initiation of plasma exchange (PE) therapy in addition to high-dose corticosteroid and multiple immunosuppressants.

Methods: Retrospective study of DM patients who satisfied the ACR/EULAR classification criteria attending Tokai University Hospital between 2010 and 2019, screened for autoantibodies, and with RP-ILD diagnosed based on the clinical course of respiratory symptoms, function and computed tomography. A model combining 4 serum biomarkers (ferritin ≥ 500 ng/mL, CRP ≥1 mg/dL, KL-6 ≥1,000 U/mL and anti-MDA5 antibody positivity) was used for predicting poor prognosis. All patients received intensive immunosuppressive therapy (high-dose prednisolone (PSL) including methyl-PSL pulse therapy, calcineurin inhibitor and/or intermittent intravenous cyclophosphamide). In addition to this, one group of patients also underwent PE. Comparisons of treatment response and prognosis between the two groups were assessed using Fisher’s exact test and paired or unpaired t-test.

Results: Fifteen DM/CADM patients with RP-ILD and at least 3 factors predicting poor prognosis were identified, 7 of whom had classic DM and 8 had CADM. Of these 15 patients, 11 (5 female, 6 male, mean age 57 ± 12 SD, range 38-75 years) received intensive immunosuppressive therapy (IS group) and 4 received PE therapy in addition to immunosuppressive therapy (PE group, 2 female, 2 male, mean age 56 ± 14 SD, range 40-70 years). PE therapy was started at the same time as immunosuppressive therapy in 3 of 4 these patients. Respiratory symptoms improved in all 4 patients receiving PE, who were still alive at the end of the study, whereas only 3 of 11 patients receiving immunosuppression alone survived (100% vs. 27%, P= 0.026). Three patients in the PE group and 3 of 11 in the IS group exhibited all 4 indicators of poor prognosis conferring the highest risk of death. Notably, of these 6 patients, all 3 in the PE group but none in the IS group survived. Serum ferritin levels were significantly reduced in the PE group (1459 ng/mL vs. 57 ng/mL, P= 0.043), with decreasing to within the normal range in all 4 patients. Moreover, the mean ferritin level in the PE group after remission was significantly lower than in the IS group (57 vs. 3450 ng/mL; P= 0.037).

Conclusion: PE therapy, especially its early initiation in addition to intensive immunosuppressive therapy, is effective in patients with DM and severe refractory RP-ILD.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/efficacy-of-early-initiation-of-plasma-exchange-therapy-for-a-patient-with-anti-mda5-autoantibody-positive-dermatomyositis-developing-refractory-rapidly-progressive-interstitial-lung-disease/