Tocilizumab for Giant Cell Arteritis: Clinical Outcomes Following Relapses and Tocilizumab Discontinuation Due to Adverse Events.

Objective: Tocilizumab (TCZ) is effective for giant cell arteritis (GCA). However, little is known regarding treatment modification and clinical outcomes after unfavorable events, such as GCA relapses or TCZ discontinuation due to adverse events (AEs).

Methods: This multicenter retrospective study included GCA patients who initiated TCZ from 2008 to 2021 at five Japanese hospitals. GCA relapses and TCZ-related AEs were monitored for two years after TCZ initiation. In patients with GCA relapses, subsequent clinical courses, including relapse symptoms and treatment modification, were followed for 90 days after the relapses. Similarly, patients who discontinued TCZ due to AEs were additionally followed until one year after the TCZ discontinuation to evaluate AEs, relapses, and treatment changes.

Results: Of 62 eligible patients, 10 patients (16%) relapsed after initiating TCZ therapy. Most relapses (8/10) occurred after extending TCZ intervals or discontinuing TCZ. Combinations of adjusting TCZ intervals, glucocorticoid (GC), and/or methotrexate (MTX) could manage the relapses without serious complications. In the entire cohort, AEs occurred in 28 patients (45%), and 8 patients (13%) discontinued TCZ due to AEs. After AE-related TCZ discontinuation, six patients attempted to taper GC without other immunosuppressive treatments, and four subsequently relapsed. In contrast, two patients who used other immunosuppressants or biological therapy could decrease GC without relapses.

Conclusion: Although GCA relapses can occur after initiating TCZ therapy, most relapses can be safely managed by adjusting TCZ, GC, and/or MTX. Adding immunosuppressants or biological treatments may potentially be related to preventing relapses when patients discontinue TCZ due to AEs.