Successful treatment of refractory myositis-associated interstitial lung disease with an interleukin-6 inhibitor: four-patient case series

Myositis-associated interstitial lung disease (ILD) is a potentially fatal disease, despite combination therapy with glucocorticoids (GC) and other immunosuppressive agents. New therapies, including biologics targeting relevant cytokines, such as interleukin (IL)-6, are warranted. We retrospectively reviewed patients with myositis-associated ILD who were treated with the IL-6 inhibitor tocilizumab (TCZ) to determine the clinical usefulness of TCZ. Four patients with myositis-associated ILD treated with TCZ between 2019 and 2023 were identified from the records of our medical centre. All patients were female, aged 43–84 years. One patient was positive for the antimelanoma differentiation-associated gene 5 antibody, while the others were positive for anti-aminoacyl-tRNA synthetase antibodies. All patients met the classification criteria for rheumatoid arthritis. The initial GC dose was 1 mg/kg/day (40–60 mg/day) of prednisolone, and GC-pulse therapy was administered to all but one patient. TCZ treatment was initiated within 6 months of the initial treatment. All patients showed clinical and radiological improvements after TCZ therapy, achieving GC reduction or withdrawal. The Warrick score, which semi-quantitatively evaluates ILD, improved from a median of 14.5 (moderate) to 4 (mild). Furthermore, no relapse or serious adverse events were observed. TCZ is a potential treatment option for refractory myositis-associated ILD.