Case Report: Telitacicept for interstitial lung disease associated with idiopathic inflammatory myopathies: an observational study.

Background: Interstitial lung disease (ILD) is the most common complication and the major cause of mortality among patients with idiopathic inflammatory myopathies (IIMs). Currently, no recommended standard treatment for IIM-associated ILD. In this observational study, we evaluated the efficacy and safety of telitacicept in treating IIM-associated ILD. Methods: We included 10 patients with IIM-associated ILD; of them, seven had antisynthetase syndrome-associated ILD, one had anti-MDA5 antibody-positive dermatomyositis (DM)-associated ILD, and 2 had DM-associated ILD. Four patients with severe ILD were treated with a combination of rituximab (RTX) (375 mg/m2/week for 4 weeks) and telitacicept (160 mg/week). Six patients had refractory IIM-associated ILD; of them, two received RTX (375 mg/m2/week for 4 weeks) in combination with telitacicept (160 mg/week), and four were treated with telitacicept (160 mg/week) alone because they had an increased infection risk. Result: Over the 24-week follow-up, glucocorticoid dosage was reduced to 5-10 mg/day and that of telitacicept treatment was increased to 160 mg every 2 weeks in all patients. These patients exhibited alleviation of rash, joint swelling and pain, muscle pain and weakness, and dyspnea. Compared with before treatment, the Manual Muscle Testing 8 score and PaO2/FiO2 ratio increased by 25.1% and 28.2% after treatment, respectively. Lung function also exhibited considerable improvements, with percentages of forced vital capacity and diffusing capacity of the lungs for carbon monoxide increasing by 20.4% and 30.2%, respectively. Posttreatment chest high-resolution computed tomography revealed significant improvements compared with baseline. Only one patient experienced a mild lung infection, and no further infections occurred after telitacicept dose was reduced. One patient was administered additional nintedanib for pulmonary fibrosis due to insufficient improvement in lung function. Conclusion: Telitacicept demonstrates substantial clinical efficacy in the treatment of IIM-associated ILD, accompanied by a low infection rate and a favorable safety profile.