Clinical Outcomes in Patients with Rheumatoid Arthritis After Switching Between Interleukin-6-Receptor Inhibitors and Janus Kinase Inhibitors: Findings from an Observational Study.

Introduction: This observational study evaluated response in patients with rheumatoid arthritis (RA) who switched from an interleukin-6 receptor inhibitor (IL-6Ri) to a Janus kinase inhibitor (JAKi) and vice versa.

Methods: Adult patients with RA, who initiated IL-6Ri or JAKi (following discontinuation of JAKi or IL-6Ri, respectively) during/after December 2012 and had a 6-month follow-up visit were enrolled. Clinical outcomes were evaluated at baseline and the follow-up visit. Continuous outcomes included Clinical Disease Activity Index (CDAI), Health Assessment Questionnaire (HAQ), pain, fatigue, tender joint count, swollen joint count, Physician Global Assessment (MDGA), Patient Global Assessment (PtGA), and morning stiffness duration. Categorical outcomes included the proportion of patients achieving CDAI low disease activity (LDA), remission, and minimal clinically important differences (MCIDs) for HAQ, pain, fatigue, MDGA, and PtGA. Continuous outcomes were summarized as mean changes from baseline, and categorical outcomes as response rates. Differences in the outcome measures between groups were evaluated using linear and logistic regression models.

Results: Between IL-6Ri (n = 100) and JAKi initiators (n = 129), no significant differences were noted for continuous outcomes. Within both groups, a significant proportion of patients achieved LDA, remission, and MCIDs for other measures, although the odds of achieving LDA were higher among IL-6Ri (vs. JAKi) initiators with moderate-to-severe disease (adjusted odds ratio: 3.30 [1.01, 10.78]).

Conclusions: Patients with RA can achieve improvement in response when switching between IL-6Ri and JAKi. Although both therapies affect the IL-6 pathway, there are distinct mechanisms of action, which likely contribute to their clinical improvement, when reciprocally switched as follow-on treatments.