Background/Purpose: Anti melanoma differentiation-associated gene 5 (MDA5) antibody (Ab) positive dermatomyositis (DM) often complicates rapidly progressive interstitial lung disease (RP-ILD), which shows fatal prognosis at early phase from the onset in spite of intensive immunosuppressive therapies. Although relapse of RP-ILD after remission with initial treatment is relatively rare in this condition, its long-term clinical course still remains unclear. Therefore, we investigated clinical characteristics and possible indicators for early detection of recurrence in patients with anti-MDA5 Ab positive DM and RP-ILD.

Methods: Adult Japanese DM patients who were treated at Tokai University Hospital from 2012 to 2019 were screened. Anti-MDA5 Ab was identified by immunoprecipitation with [35S] methionine-labeled HeLa cells, and anti-MDA5 Ab titers were measured using anti-MDA5 enzyme-linked immunoabsorbent assay. Patients who showed the exacerbation of RP-ILD and/or DM symptom after stabilized for more than a year were considered as recurrence. Clinical and immunological features were retrospectively collected. Statistical analyses were performed using the Fisher’s exact test.

Results: Thirty patients were diagnosed as DM with anti-MDA5 Ab. All had ILD and required hospitalization for intensive treatment. Seventeen of 30 (57%) achieved an improvement in respiratory function in response to their initial treatment and were discharged from the hospital. During their disease courses in outpatient care, 3 (18%) of 17 patients experienced recurrence and required re-hospitalization. Among 3 relapsed cases, 2 (67%) showed exacerbation of RP-ILD and remaining 1 (33%) revealed muscle weakness. Although all 3 relapsed patients showed anti-MDA5 Ab titer elevation at the time of relapse, no increase in the titer was seen in 14 non-relapsed patients (100% vs. 0%, P=0.002) Interestingly, marked increase of anti-MDA5 Ab titers preceded appearance of recurrent symptoms in all relapsed cases, whereas ferritin levels were within normal range at the recurrence (38-120 ng/dl) and gradually increased after readmission.

Conclusion: These results suggest that continuous measurement of anti-MDA5 Ab titer as well as careful observation of physical and imaging findings is crucial for monitoring disease activity and early detection of relapse in patients with anti-MDA5 Ab positive DM.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/anti-melanoma-differentiation-associated-protein-gene-5-antibody-titer-monitoring-is-a-useful-indicator-for-early-detection-of-recurrence-in-rapidly-progressive-interstitial-lung-disease-associated-wi/