Rituximab for refractory rapidly progressive interstitial lung disease related to anti-MDA5 antibody-positive amyopathic dermatomyositis.

To report our experience in using rituximab (RTX) for treating refractory rapidly progressive interstitial lung disease (RP-ILD) complicating anti-melanoma differentiation-associated gene 5 antibody (anti-MDA5 Ab)-positive amyopathic dermatomyositis (ADM). Medical records of four ADM patients with refractory RP-ILD treated with RTX therapy were reviewed retrospectively. All four patients were tested positive for anti-MDA5 Ab and failed to respond to high-dose systemic steroid and other intensive immunosuppressive therapies. Respiratory symptoms, lung function tests, and high-resolution computed tomography (HRCT) of the chest were compared before and after the first course of RTX. After RTX treatment, all four patients had improvement in the respiratory symptoms in terms of New York Heart Association classification. Two patients successfully had their supplementary oxygen therapy weaned off. The lung function tests were significantly better in all patients. The HRCT showed improvement in three patients while the other one remained static. The recalcitrant vasculitic rashes associated with the anti-MDA5 Ab were also better in all patients. The average daily prednisolone dose dropped from 20 to 6.25 mg post-treatment. None of the patients died throughout the follow-up period which ranged from 6 months to 2 years. However, two patients developed chest infection and one wound infection within 6 months after the RTX infusion. Our results suggest that RTX may be a useful therapy for anti-MDA5 Ab-positive ADM associated with RP-ILD. However, infection is the major risk.