Objective To determine the predictors of the therapeutic effects of tocilizumab (TCZ) switched from other biologics with different mechanisms of action in rheumatoid arthritis (RA).
Methods Patients who switched from tumor necrosis factor inhibitors (TNFis) or abatacept (ABT) to TCZ were analyzed. They were categorized into two groups based on clinical disease activity at week 24 (response group: 28-joint disease activity score with erythrocyte sedimentation rate (DAS28-ESR) (3) ≤ 3.2, and non-response group: DAS28-ESR (3) > 3.2). We compared DAS28-ESR (3) at the initiation of TCZ therapy (ΔDAS) in patients switching from TNFis and ABT. We examined whether the therapeutic effect of TCZ switched from TNFis and ABT could be predicted using clinical parameters.
Results Sixty-seven patients were analyzed (TNFis, 53; ABT, 14); of these, 36 (67.9%) patients who received TNFis and 6 (42.9%) who were treated with ABT were considered responders. In patients who switched from TNFis, ΔDAS in the non-response group was significantly lower than that in the response group until week 8, and the improvement in the non-response group reached a plateau at week 12. Conversely, in patients treated with ABT, ΔDAS was significantly different between the response and non-response groups in the early phase, i.e., at week 4. In univariate regression analysis, ΔDAS at week 4 was correlated with DAS28-ESR (3) at week 24 (p < 0.05) in patients switching from ABT. Receiver operating characteristic analyses suggested that 0.74 was the optimal ΔDAS cutoff at week 4 to predict response vs. non-response at week 24 (sensitivity: 100%, specificity: 87.5%, p < 0.001).
Conclusion The efficacy of TCZ may vary depending on which biologics were used previously. The effectiveness of TCZ switched from ABT could be predicted by the therapeutic response at week 4.