1. The addition of tocilizumab, a monoclonal antibody against interleukin-6 (IL-6), to a glucocorticoid taper sustained remission in patients with giant-cell arteritis (GCA) through one year more effectively than glucocorticoids alone.
2. The addition of tocilizumab reduced the cumulative prednisone dose given over the trial period and the incidence of flares, without an increase in the rate of adverse events.
Evidence Rating Level: 1 (Excellent)
Study Rundown: GCA is a chronic vasculitis associated with systemic inflammation and severe complications, such as vision loss and cerebral ischemia. Glucocorticoids have been the only effective treatment to date, but long-term use is associated with significant adverse effects. This trial examined the efficacy and safety of adding tocilizumab, a monoclonal antibody against the proinflammatory cytokine IL-6, to glucocorticoids in patients with GCA. The primary endpoint – sustained remission over the 52-week trial period – was significantly greater in patients treated with tocilizumab combined with prednisone compared to prednisone alone. Key secondary endpoints – including cumulative prednisone doses, the incidence of flare after remission, and quality of life metrics – were all favorable for tocilizumab compared to placebo. The rate of serious infections with tocilizumab was consistent to the known safety profile established in previous studies, and there was no significant difference in adverse event rates between tocilizumab and placebo. This trial helps establish tocilizumab as the first effective non-steroid treatment for GCA.
GiACTA is a phase III, randomized, double-blinded, placebo-controlled trial and the largest to evaluate the management of GCA. Though the variability in disease presentation challenged validity, strict definitions of remission and flare were used to limit inaccuracy. Since tocilizumab reduces C-reactive protein (CRP), researchers were blinded to CRP levels to prevent unblinding. The trial was limited by its duration, and studies are needed to address efficacy and safety of tocilizumab beyond one year.
In-Depth [randomized controlled trial]: Patients (n = 251) were enrolled and randomized in a 2:1:1:1 ratio to tocilizumab every week plus a 26-week prednisone taper (n = 100), tocilizumab every other week plus a 26-week prednisone taper (n = 50), placebo plus a 26-week prednisone taper (n = 50), or placebo plus a 52-week prednisone taper (n = 51). Sustained remission was defined as the absence of flare and normalization of CRP levels (<1 mg/dL) within 12 weeks and maintained through the 52-week trial period. Flares were determined by the investigator and defined as a recurrence of signs or symptoms and/or ESR ³30 mm/hr. The Short-Form (SF)-36 Questionnaire was used to define quality of life.
The primary endpoint of sustained remission was met by 56% of patients who received tocilizumab weekly and 53% of those who received tocilizumab every other week, compared with 14% of patients who received placebo and 26-week prednisone taper and 18% of those who received placebo and 52-week prednisone taper (p < 0.001 for all comparisons of tocilizumab vs. placebo). The percentage of patients who had flares were 23% in the tocolizumab weekly group (99%CI 0.11-0.46, p < 0.001 vs. placebo and 26-week taper), 26% in tocilizumab every other week (99%CI 0.12-0.66, p < 0.001 vs. placebo and 26-week taper), 68% in placebo with 26-week prednisone taper, and 48% in placebo with 52-week prednisone taper. Total median cumulative prednisone doses over the 52-week period were 1862 mg with tocolizumab weekly (95%CI 1582-1942 mg) and every other week (95%CI 1568-2240 mg), 3296 mg with placebo and 26-week prednisone taper, and 3818 mg with placebo and 52-week prednisone taper (p < 0.001 for all comparisons of tocilizumab vs. placebo). The difference in quality of life scores between tocilizumab weekly and placebo with 52-week taper was 5.59 points on the SF-36 scale (99%CI 0.86 to 10.32, p = 0.002). No statistical difference in any adverse event was reported. Infection was the most common adverse event reported in all trial groups.
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