Background/Purpose: The efficacy and safety of tocilizumab (TCZ), an IL-6 receptor-alpha inhibitor, was evaluated in patients with giant cell arteritis (GCA) in GiACTA, a randomized, double-blind, placebo-controlled trial with blinded glucocorticoid regimens of variable dose and duration (Int J Rheumatol. 2013:912562). Data up to week 52, the time of primary outcome measurement, are presented.

Methods: Patients aged ≥50 years had active GCA previously confirmed by temporal artery biopsy or cross-sectional imaging and documented acute-phase reactant elevation attributable to GCA. Randomization was stratified by baseline prednisone dose (≤30 or >30 mg/day). Patients were randomized 1:1:2:1 to 4 groups: A, short-course prednisone (26-week prednisone taper + weekly subcutaneous [SC] placebo); B, long-course prednisone (52-week prednisone taper + weekly SC placebo); C, weekly SC TCZ 162 mg + 26-week prednisone taper; D, every other week SC TCZ 162 mg + 26-week prednisone taper. The baseline prednisone dose (20-60 mg/day) was selected by the investigator. Prednisone doses <20 mg/day were blinded. Patients who flared or could not adhere to the protocol-defined tapering schedule received open-label prednisone escape therapy but continued on double-blind TCZ/placebo. Sustained remission was defined at week 52 as the absence of flare and normalization of C-reactive protein after week 12, combined with adherence to the protocol-defined prednisone taper. The primary and key secondary end point was the proportion of patients in sustained remission, comparing both TCZ groups (C, D) with the short-course prednisone group (A) and with the long-course prednisone group (B), respectively, at a significance level of 0.005. A dose hierarchy of statistical testing was implemented. Cumulative prednisone exposure was a secondary end point.

Results: Of 251 patients randomized, the mean ± SD age was 69 ± 8.2 years, and 75% were female. In the primary comparison, 56% of patients in the weekly TCZ group and 53.1% in the every other week TCZ group achieved sustained remission at 12 months compared to only 14% in the short-course prednisone group (p < 0.0001). In the key secondary efficacy comparison, the percentage of patients in sustained remission in each TCZ group was also superior to that of patients in the long-course prednisone group (17.6%) (p ≤ 0.0002). The median cumulative steroid exposure in both TCZ groups was less than half that of those in the long-course prednisone group (Table). The incidence of adverse events was similar among the 4 treatment arms. No deaths and no new vision loss occurred over the period of observation.

Conclusion: TCZ plus a 26-week prednisone taper was superior to both short- and long-course prednisone tapers for the achievement of sustained remission at 52 weeks. The addition of TCZ to prednisone also led to a substantial reduction in the cumulative prednisone doses required to control GCA.