Baricitinib in rheumatoid arthritis in real-world clinical practice: pooled analysis of the overall patient cohort and a subgroup of patients with difficult-to-treat disease according to the Moscow registry

Baricitinib (BARI) is widely used in rheumatoid arthritis (RA); however, real-world data on its place in therapy and efficacy in patients with difficult-to-treat (D2T) RA are limited.
Objective: to assess the clinical and demographic characteristics of patients with RA, including those in the D2T RA subgroup, the outcomes of BARI use in routine practice across different lines of therapy (LT) and switching strategies, as well as its steroid-sparing effect.
Material and methods. A retrospective analysis was performed of patients included in the Moscow registry of immune-mediated inflammatory/autoimmune diseases who were followed up from 19.08.2021 to 26.12.2024 and were prescribed BARI. Data from three visits (V1–V3) with a 6-month interval were analyzed. Study endpoints were changes in DAS28-ESR/CRP, CDAI/SDAI, tender joint count (TJC) and swollen joint count (SJC), patient and physician global assessment of disease activity; the proportion of patients in remission and with low disease activity; the number of patients receiving glucocorticoids (GCs) and methotrexate (MTX), as well as GCs and MTX doses. Current therapy at the time of the study and prior therapy were analyzed; a separate analysis was performed for the D2T RA subgroup.
Results and discussion. The study included 188 patients (82% women); mean age was 56.0±12.1 years; median RA duration was 11 (7–18) years. The mean follow-up duration was 12.6 (2.3–29.7) months. The intervals between visits averaged 6.5 months. The D2T RA subgroup included 17 (9%) patients. BARI was prescribed as 1st LT in 62.2% of patients, as 2nd LT in 14.9%, and as 3rd LT in 22.9%; 62.2% of patients had not previously received biologic DMARDs (bDMARDs) or targeted synthetic DMARDs (tsDMARDs), whereas 37.8% were switched to BARI from bDMARDs or tsDMARDs. By V3, with BARI used as 1st LT, the median DAS28-ESR decreased from 3.4 to 3.1 (-8.8%; p<0.05); as 2^nd LT, from 3.3 to 2.9 (-12.1%); and as 3rd LT, from 4.1 to 2.9 (-29.3%); the median DAS28-CRP decreased by 6.9%, 6.9%, and 24.1%, respectively. The greatest reduction in activity indices was observed after switching from interleukin-6 inhibitors (IL-6i): the median DAS28-ESR decreased from 4.02 to 2.99 (-25.6%; p=0.0174) and CDAI from 14.47 to 10.88 (-24.8%). The smallest decrease in indices was recorded after prior therapy with Janus kinase inhibitors (JAKi). In such patients, DAS28-ESR decreased on average by 3.0%, while CDAI increased by 9.1%. In the D2T RA group, a significant reduction in SJC (-74.1%) and TJC (-59.6%) was noted (p<0.05), with a clinically noticeable but statistically non-significant decrease in DAS28-ESR (-18.3%), DAS28-CRP (-23.8%), CDAI (-34.6%), and SDAI (-39.4%). By V3, in 52.1% of patients (p<0.05) it was possible to reduce the GCs dose (21.7%) or discontinue GCs completely (30.4%); the MTX dose and the proportion of patients receiving it also decreased.
Conclusion. In real-world practice, BARI therapy provided a reduction in RA activity across different LT and demonstrated a steroid-sparing effect. Even in patients with D2T RA, a clinically meaningful decrease in arthritis activity was observed. The most favorable switching outcomes were noted in patients previously treated with IL-6i, whereas in patients who had used JAKi, the effect of BARI was limited, which is associated with a change in the mechanism of action when another drug is prescribed. These findings require confirmation in prospective studies.

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