Background/Purpose: Autoantibodies to Melanoma Differentiation-Associated Gene 5 (MDA5) are found specifically in patients with dermatomyositis (DM). Their presence is closely associated with rapidly progressive interstitial lung disease (RP-ILD) and poor prognosis. Although RP-ILD is a life-threatening condition, relapse of RP-ILD has rarely been reported after the success of the initial treatment. Nonetheless, some patients do relapse, but the clinical features and changes in laboratory biomarkers at the time of relapse of RP-ILD in patients with anti-MDA5-positive DM remain unclear. The aim of this study was to establish the clinical features of anti-MDA5-positive RP-ILD in patients with exacerbations after remission had been achieved.

Methods: Forty-one patients with classic DM or Clinically Amyopathic (CA) DM and ILD who were seen at Tokai University from 2011 to 2021 were retrospectively evaluated for their clinical and immunological characteristics including the occurrence of relapse during the clinical course after remission induction. Anti-MDA5 antibody was assayed by protein immunoprecipitation and enzyme-linked immunosorbent assays. Comparisons between relapse and non-relapse groups were made using the chi-square test.

Results: Forty-four patients with DM or CADM were found to have anti-MDA5 antibody. Three were excluded from the analysis because of insufficient clinical/immunological information. Of 41 patients (male/female: 7/34, mean age ± SD: 55.2 ± 11.9), 13 (32%) died despite initial intensive immunosuppressive treatment at an early phase of disease. Twenty-three patients achieved remission with the initial therapy and did not relapse during follow-up (56%). The remaining 5 patients (12%) in remission on initial treatment later relapsed. Of these 5 patients (male/female: 2/3, a mean age ± SD: 49.8 ± 11.2), one had classic DM and 4 had CADM. At the time of relapse, two patients complained of respiratory symptoms and all had worsening abnormal shadow on high resolution computed tomography (HRCT). Serum CRP, KL-6 and ferritin levels tended to be increased at the time of relapse. In 3 of the 5 (60%), the anti-MDA5 antibody titer was again above the cut-off level at relapse. The number of relapsing patients with anti-MDA5 antibody titer increasing again above the cut-off level was higher than in those who did not relapse (60% vs. 0%, P=0.003).

Conclusion: These results indicate that relapse may occur even after complete remission of RP-ILD has been achieved. Increased anti-MDA5 antibody titers, as well as respiratory symptoms and HRCT findings, are potential indicators of RP-ILD relapse in patients with DM.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/relapse-of-rapidly-progressive-interstitial-lung-disease-in-patients-with-anti-melanoma-differentiation-associated-gene-5-autoantibody-positive-dermatomyositis/