Clinically Inactive Disease and Remission in Patients with Juvenile Idiopathic Arthritis Receiving Tofacitinib: Post-Hoc Analysis of a Phase III Trial.

OBJECTIVE To evaluate rates of clinically inactive disease and remission in patients with juvenile idiopathic arthritis (JIA) receiving tofacitinib, using the 2021 Juvenile Arthritis Disease Activity Score (JADAS) thresholds and American College of Rheumatology (ACR) criteria. METHODS This post hoc analysis included patients with active JIA (polyarticular course JIA, psoriatic arthritis, or enthesitis-related arthritis) enrolled in a phase III, randomized, withdrawal study of tofacitinib. In part 1 (weeks 0-18) patients received open-label tofacitinib. In part 2 (weeks 18-44) patients who achieved ACR improvement ≥30% were randomized to tofacitinib or placebo for 26 weeks/until JIA flare. Disease activity was assessed using the JADAS in 10 joints (JADAS10), based on C-reactive protein, with interpretation as per 2021 polyarthritis thresholds. JADAS10 remission was defined as ≥24 continuous weeks of JADAS10 clinically inactive disease (JADAS10-CID). ACR clinically inactive disease (ACR-CID) and ACR clinical remission were also assessed. RESULTS Of 225 patients with JIA in part 1, 173 (76.9%) were randomized in part 2 to continue tofacitinib or switch to placebo. Rates of JADAS10-CID and ACR-CID increased throughout part 1 to 30.5% and 15.8% (week 18), respectively. In part 2, these were sustained with tofacitinib (week 44: JADAS10-CID: 35.2%; ACR-CID: 25.0%) and decreased when patients switched to placebo (week 44: JADAS10-CID: 25.9%; ACR-CID: 15.3%). A small proportion of patients achieved JADAS10 remission at week 44 (tofacitinib: 14.8%; placebo: 7.1%). CONCLUSION In patients with JIA receiving tofacitinib, JADAS10-CID and ACR-CID rates improved rapidly and were sustained over time; a small proportion of patients achieved JADAS10 remission. Inactive disease is a feasible treatment target in patients receiving tofacitinib.