Authors: Jack G. Mouhanna, Wei Sim, Danah Albreiki.

Disclosure Block: J.G. Mouhanna: None. W. Sim: None. D. Albreiki: None.

Abstract Body:

Purpose: Tocilizumab (TCZ) is an IL-6 receptor antagonist monoclonal antibody that has been shown to be an effective steroid sparing agent to induce and maintain remission in giant cell arteritis (GCA). Case series and case reports suggest TCZ may be effective in sustaining remission in patients with refractory GCA and patients with aortitis due to inflammatory conditions. This study aims to examine the effectiveness of TCZ in 2 patients with refractory GCA with evidence of aortitis, which has been associated with disease relapse and glucocorticoid dependence.
Study Design: This is an observational case series of 2 patients who received TCZ for refractory biopsy-proven GCA.
Methods: The patient charts were retrospectively reviewed. One patient was assigned the letter A and the other the letter B.
Results: Both patients had a similar course. Patient A was a 67-year-old female (at the time of temporal artery biopsy) who was started on weekly TCZ 3 years following GCA diagnosis. Patient B was a 58-year-old female with a history of recurrent flares of polymyalgia rheumatica prior to GCA and was started on weekly TCZ 1 year following GCA diagnosis. Both patients were treated with methotrexate in addition to glucocorticoids and experienced disease relapses before starting TCZ, leading to glucocorticoid dose increases and dependence. Both patients had blurry vision on presentation but no objective vision loss or findings on examination. Patient A had blood pressure discrepancy in the upper extremities and Patient B had lightheadedness on exertion; further investigations showed evidence of aortitis on CT imaging. Neither patient experienced a relapse on TCZ (18 months for Patient A and 2 years for Patient B). Glucocorticoids were completely tapered within 1 year in both patients (from 60mg in Patient A and 15mg in Patient B at the time of TCZ initiation). The inflammatory biomarkers ESR and CRP were relatively low before TCZ treatment and were lower afterwards (average ESR of 16 decreasing to 2; average CRP of 5.8 decreasing to <0.3). Finally, there were no side effects reported.
Conclusions: TCZ appears to be safe and effective in treating refractory GCA and glucocorticoid dependence. The association between aortitis and refractory GCA raises the question of whether patients with refractory GCA should be investigated for aortitis as a potential underlying risk factor. More studies are needed to establish the potential benefit of TCZ in this subset of patients and the prognosis of patients with refractory GCA and large-vessel involvement.