Some patients with giant cell arteritis (GCA) maintain remission up to a year after discontinuation of tocilizumab therapy, according to long-term results from the GiACTA trial.
Part one of the trial showed that tocilizumab plus blinded prednisone taper was more effective than placebo plus prednisone taper for inducing a sustained remission. “However, the duration of the effects of tocilizumab is unknown,” wrote study authors led by Professor John Stone of Harvard Medical School in The Lancet Rheumatology.
The second phase of the GiACTA trial included 215 patients with GCA. There were 81 patients who had been randomised to once-weekly tocilizumab in the first phase who were in clinical remission after one year, and 59 of those started phase two with no treatment.
Of those 59 who started with no further treatment, 25 of them (42%) remained in tocilizumab- and glucocorticoid-free clinical remission throughout the next year. Of 28 patients who had received tocilizumab every other week, eight (29%) maintained such a remission for the full second year.
The median cumulative glucocorticoid dose over the full three years of the trial were lower in patients who received tocilizumab than in those who did not. For those in the once-weekly tocilizumab group, the median cumulative dose was 2,647 mg; in the twice-weekly group, it was 3,948 mg. For patients who were in the placebo group with a 26-week prednisone taper, the cumulative dose was 5,277 mg, and it was 5,323 mg for those in the placebo plus a 52-week taper.
Among patients who did experience a relapse in phase two of the trial, tocilizumab was able to restore clinical remission. The median time to remission was 15 days in 17 patients treated with tocilizumab alone, and 16 days for 36 patients treated with tocilizumab plus glucocorticoids. The time to remission was 54 days in 27 patients treated with glucocorticoids alone.
“Giant cell arteritis remains a chronic disease that entails ongoing management and careful vigilance for disease relapse, but continuous indefinite treatment with immunosuppressive drugs is not required for all patients,” the authors concluded.
In an accompanying editorial, Dr Kaitlin Quinn, of the National Institutes of Health, wrote that decisions regarding optimal duration of therapy required weighing the risks and benefits of prolonged immunosuppression with the potential for future disease relapse.
“Long-term analyses of randomised controlled trials in rheumatoid arthritis have not shown an increased safety signal with increasing exposure to tocilizumab,” she wrote.
Dr Quinn noted that vascular inflammation may still persist in patients with GCA who appeared to be in clinical remission, explaining why most patients did relapse after discontinuation of therapy.
“Encouragingly, we are finally reaching a … point in GCA where we can begin to shift focus from identification of effective glucocorticoid-sparing therapies to learning how to use these medications most effectively during later phases of the disease,” she wrote.