Objectives: Anti-melanoma differentiation-associated protein-5 (MDA5) autoantibodies (Abs) are associated with rapidly progressive interstitial lung disease (RP-ILD) in dermatomyositis (DM). Because the addition of plasma exchange (PE) and rituximab (RTX) to triple therapy is inadequate in severe cases, we treat such cases with intensive induction therapy (IIT) combining all these options with tofacitinib (TOF). In this study, we investigated the poor prognostic factors and the efficacy and safety of IIT.
Methods: Thirty-three patients diagnosed with anti-MDA5 Ab-positive DM in our institution between 2014 and 2021 were included. The clinical characteristics of poor prognosis were retrospectively analysed using principal component analysis (PCA), and the outcomes of IIT were analysed in terms of survival, assessed using the Kaplan-Meier test, and adverse events.
Results: Although triple therapy with RTX, PE, or intravenous immunoglobulin was administered before the introduction of IIT, eight of 12 RP-ILD cases with a ferritin level >400 ng/mL (mean, 2,342) died within a median of 2.5 months. PCA revealed distinct clusters for prognosis, and age and serum ferritin were leading predictors of the prognosis. IIT, consisting of combinations of triple therapy with higher doses of methylprednisolone, PE, RTX, and TOF, was applied to eight patients (mean ferritin, 3,558). Although two patients died even with these regimens, a significant improvement in survival was documented. Several IIT-related adverse events were observed, including viral and fungal infections and cytopenia.
Conclusions: IIT significantly improved the survival of patients with severe anti-MDA5 Ab-positive RP-ILD. Although infections are noted, their benefits outweigh the risks in younger patients with high serum ferritin levels.