Anti-transcriptional intermediary factor 1-γ antibody as a biomarker in patients with dermatomyositis.

The presence of anti-transcriptional intermediary factor (TIF)1-γ antibody (Ab) is associated with cancer in adult patients with clinically amyopathic dermatomyositis (CADM) or dermatomyositis (DM). In this study, we examined whether anti-TIF1-γ Ab levels are associated with disease activity in patients with CADM/DM. Anti-TIF1-γ Ab levels were examined in 23 patients with CADM or DM (CADM, n = 6; DM, n = 17). Baseline characteristics and outcomes were recorded, and serial measurements of anti-TIF1-γ Ab levels were obtained. Of the 23 patients with detectable anti-TIF1-γ Ab, 16 (70%) had an internal malignancy, while two (9%) had interstitial lung disease. Mean initial anti-TIF1-γ Ab levels (134 ± 47 index) were significantly decreased after 24 months (54 ± 45 index, P < 0.0001) and remained decreased thereafter. Anti-TIF1-γ Ab became negative (index value, <32) in 10 patients (43%) and remained positive (index value, ≥32) in 13 patients (57%) during the clinical course. The frequency of remission in the anti-TIF1-γ Ab-negative conversion group (100%) was significantly higher than in the sustained positive group (0%, P < 0.0001). Furthermore, mortality in the anti-TIF1-γ Ab-negative conversion group (0%) was significantly lower than that in sustained positive group (69%, P < 0.001). This study indicates that anti-TIF1-γ Ab levels are a useful and relevant surrogate marker of disease activity during follow-up monitoring.