Background/Purpose: Although clinical trials have shown similar effectiveness between Janus kinase inhibitors (JAKi) and biologic disease-modifying anti-rheumatic drugs (bDMARDs), the choice between these two options is currently a crucial question in real-world practice. However, there is a lack of sufficient real-world evidence comparing the outcomes and safeties of these treatments in patients with rheumatoid arthritis (RA). This study aimed to assess the efficacy and safety of JAKi compared to bDMARDs in Korean patients with RA who have not previously received either JAKi or bDMARDs.

Methods: In this prospective, multicenter, quasi-experimental study conducted at 17 centers in South Korea, we enrolled patients who had an inadequate response to Methotrexate (MTX) and initiated either Janus kinase inhibitors (JAKi) or biologic disease-modifying anti-rheumatic drugs (bDMARDs). The primary objective of the study was to assess the proportion of patients achieving low disease activity (LDA) at 24 weeks, as measured by the disease activity score (DAS) 28 erythrocyte sedimentation rate (ESR). Secondary endpoints included remission rate at 24 weeks, as well as LDA rates at 12 weeks and 48 weeks. Furthermore, we compared the safety profiles of the two treatment groups during the follow-up period.

Results: A total of 506 patients were enrolled in the study, with 253 patients in each of the JAKi and bDMARDs groups between April 2020 and August 2022. Among the bDMARDs users, 60.1% received TNFi (n = 152), while 39.9% received non-TNFi (n = 101). In the JAKi group, 48.6% received baricitinib (n = 123), 24.9% received tofacitinib (n = 63), and 26.5% received upadacitinib (n = 67). The two groups were comparable in terms of age (53.2 vs. 54.2) and the proportion of females (83.0% vs. 86.2%). Most patients in both groups received combination therapy with MTX (89.3% in both groups) and glucocorticoids (89.3% vs. 83.8%). At baseline, the bDMARDs group had slightly higher DAS28-ESR compared to the JAKi group (6.1 vs. 5.9, p=0.039). The primary endpoint, achieving LDA at 24 weeks, was observed in 48.2% of the JAKi group and 42.7% of the bDMARDs group (p=0.246). Regarding secondary endpoints, the remission rate at 24 weeks was 28.9% in the JAKi group and 27.3% in the bDMARDs group. Among patients receiving glucocorticoids at baseline (n=438), the rates of achieving glucocorticoid-free remission at 24 weeks were similar between the two groups (6.2% in bDMARDs and 8.5% in JAKi). The JAKi group showed a higher rate of achieving LDA at 12 weeks compared to the bDMARDs group, with marginal significance (45.9% vs. 38.3% based on DAS28 ESR, p=0.105). Currently, these patients are undergoing follow-up to gather data on the effectiveness and safety of the treatment at the 48-week mark.

Conclusion: In this real-world study involving Korean patients with RA eligible for targeted therapy, the profiles of JAKi users were similar to those of bDMARDs users. The study found that JAKi demonstrated comparable effectiveness and safety to bDMARDs users.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/real-world-comparative-effectiveness-study-of-janus-kinase-inhibitors-compared-to-biologic-disease-modifying-antirheumatic-drugs-in-korean-patients-with-rheumatoid-arthritis/