The effectiveness of steroid-sparing agents in Giant Cell Arteritis (GCA) has been underwhelming and inconsistent. In a double-blind, randomized, controlled trial presented today at the Late Breaking Abstracts (abstract#9L), the efficacy of abatacept plus prednisone vs prednisone alone was assessed. In this trial, all patients with new or relapsing GCA received high-dose corticosteroids plus IV abatacept 10 mg/kg at weeks 0, 2, 4 and 8, then at week 12 they were randomized to continue abatacept monthly vs prednisone. According to the protocol, the prednisone taper was to be completed at 28 weeks in both groups. The primary outcome was relapse-free survival at 12 months follow-up.
This was a small study with 41 patients randomized to the two groups. Despite the small sample size, abatacept significantly increased relapse-free survival with a time to relapse of 9.9 months for abatacept vs 3.9 months for prednisone (P=0.049). There was no difference in adverse events.
After many disappointing studies of DMARDs in GCA, it is reassuring that abatacept showed benefit in a RCT. However, abatacept is definitely not a miracle drug in GCA. At 12 months, 48% of patients in the monthly abatacept group and only 31% in the placebo group were relapse free, even though both groups received abatacept initially. Clearly, we cannot get rid of prednisone and a fast prednisone taper is not effective.
A larger study of abatacept in GCA and cost-effectiveness data are needed, but in the meantime, abatacept appears to be an option for those challenging GCA patients with frequent flares or severe intolerance to prednisone.