Tofacitinib Reduces KL-6 Levels in Patients With Rheumatoid Arthritis-Associated Interstitial Lung Disease. Results Of A Phase II Investigator-Initiated Study.

OBJECTIVES: To evaluate the safety and efficacy of tofacitinib in rheumatoid arthritis-associated interstitial lung disease (RA-ILD), along with KL-6 levels during 48 weeks of follow-up. METHODS: RA-ILD patients received tofacitinib 5 mg BID for 48 weeks. The primary outcome was the incidence of adverse events. Secondary outcomes included the rate of decline in FVC, the incidence of a combined outcome of mortality and/or progressive pulmonary fibrosis (PPF), disease activity, and serum levels of KL-6 as a biomarker of lung disease. RESULTS: Thirty-nine patients participated in the trial. Thirty-six (92%) had any adverse event; Three patients died. Upper airway respiratory infections were the most frequent adverse events. Fifteen patients (38.5/100 patient-years) had the combined outcome of mortality and/or PPF. At the final visit, 51% of patients had low disease activity (SDAI index). The rate of change in FVC at 48 weeks of follow-up was -72 mL. Serum KL-6 levels declined from baseline values to 48 weeks of follow-up (baseline LSM 34358 mU/mL to 32191 mU/mL, with an LSM decline of -2167 mU/L). Nine patients initiated nintedanib during the trial; the decline in KL-6 was no different in nintedanib-treated patients, nor was the incidence of adverse events. CONCLUSION: This trial estimates the rates of adverse events, mortality, low disease activity, PPF, decline in FVC in RA-ILD, and decline in serum KL-6 in patients treated with tofacitinib NCT05246293.