Session Type: Abstract Submissions (ACR)
Background/Purpose: The presence of anti-CADM-140/ (Melanoma Differentiation-Associated Gene 5: MDA5) autoantibody is specific for adult dermatomyositis (DM), especially in patients with little or no muscle manifestations (clinically amyopathic dermatomyositis: CADM). Its presence is known to have a strong association with rapidly progressive interstitial lung disease (RP-ILD). Recently, it was reported that anti-CADM-140/MDA5 antibody titers measured by an enzyme-linked immunosorbent assay (ELISA) were useful for predicting outcomes of RP-ILD as well as for monitoring disease activity in patients with adult DM and RP-ILD. However, despite its diagnostic utility in adult DM, its clinical significance in juvenile DM (JDM) is still unclear. Here, we have examined this issue using anti-CADM-140/MDA5 ELISA.
Methods: Serum samples from 35 patients diagnosed with JDM (26 with classical JDM and 9 with juvenile CADM) were screened for autoantibody using a previously established anti-CADM-140/MDA5 ELISA. Associations between anti-CADM-140/MDA5 titer and clinical course and outcome were analyzed.
Results: Sera from 11 of 35 patients (31%) with JDM were found to contain anti-CADM-140/MDA5 antibody (6 with classical JDM and 5 with juvenile CADM). All 11 patients who possessed anti-CADM-140/MDA5 antibody had ILD, of whom 6 developed RP-ILD. JDM patients with anti-CADM-140/MDA5 antibody were significantly more likely to have RP-ILD compared with those without this antibody (P=0.0017). In anti-CADM-140/MDA5-positive patients, the mean antibody titer before treatment was significantly higher in those with RP-ILD than in those without (166.7 units vs. 57.4 units, P= 0.048). Four of 6 patients with RP-ILD died despite intensive therapy. In a patient who responded to therapy and survived, the titer of anti-CADM-140/MDA5 antibody decreased to the cut-off level, in parallel with improved respiratory symptoms. In contrast, the mean anti-CADM-140/MDA5 titer in patients who failed to respond to therapy and died did not decrease significantly, being maintained at a high level over the disease course as also observed in patients with adult DM (197.2 units vs. 76.2 units, P=0.17, n=3).
Conclusion: These results illustrate the clinical utility of establishing anti-CADM-140/MDA5 antibody titers in patients with JDM and RP-ILD as well as in patients with adult DM and RP-ILD.
Holding a patent on anti-CADM-140/MDA5 antibody-measuring kit,
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ACR Meeting Abstracts - https://acrabstracts.org/abstract/clinical-utility-of-anti-cadm-140melanoma-differentiation-associated-gene-5-autoantibody-titers-in-patients-with-juvenile-dermatomyositis-and-rapidly-progressive-interstitial-lung-disease/