Drug Discov Ther. 2026;20(2):175-189. (DOI: 10.5582/ddt.2026.01008)

Efficacy and safety of filgotinib versus tocilizumab in active rheumatoid arthritis: A randomized, open-label, multicenter study with clinical and musculoskeletal ultrasound evaluation (TRANSFORM study)

Shimizu T, Kawashiri SY, Koga T, Kiya R, Morita M, Kawasaki R, Kuroda S, Tashiro S, Sato S, Yabe M, Misaki K, Hanai S, Nakagomi D, Ogasawara M, Tamura N, Watanabe R, Kanazawa H, Atsumi T, Ueki Y, Okano T, Suzuki T, Takaoka H, Hamada H, Hidaka T, Furuta S, Hosogaya N, Yamamoto H, Kawakami A

Janus kinase (JAK) and interleukin-6 (IL-6) inhibitors are therapeutic options for patients with rheumatoid arthritis (RA) with inadequate response to conventional synthetic disease-modifying antirheumatic drugs (csDMARDs); however, no randomized controlled trial has compared their efficacy and safety. Since both act through the JAK–signal transducer and activator of transcription pathway, a comparative evaluation is warranted. We conducted a prospective, randomized, open-label trial at 55 centers in Japan, randomizing patients with active RA despite csDMARD therapy in a 1:1 ratio to receive 200 mg/day filgotinib or subcutaneous tocilizumab as monotherapy; the primary endpoint was American College of Rheumatology (ACR) 50 at week 12, and secondary endpoints included clinical disease activity indices, musculoskeletal ultrasonography scores, patient-reported outcomes, and serum biomarkers through 52 weeks. Twenty-six patients were enrolled (13 per group) before study termination due to insufficient recruitment, and descriptive analyses were performed. At week 12, ACR50 was achieved in 38.5% (5/13) patients in the filgotinib group and 46.2% (6/13) in the tocilizumab group (risk difference: −7.69%; 95% confidence interval: −42.26 to 28.8). Both groups showed early and sustained improvements in disease activity from week 2. The improvement in patient global assessment scores was greater with filgotinib at week 2 but the difference diminished thereafter, and serum IL-6 level decreased with filgotinib but increased with tocilizumab. Four serious adverse events occurred with filgotinib, including infections and cardiac events. Because this study was underpowered and the analysis was descriptive, larger studies are needed to confirm these findings and define optimal use. (The study was registered in the Japan Registry of Clinical Trials (https://jrct.niph.go.jp) as jRCTs071200107 and in ClinicalTrials.gov as NCT05090410.)

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