Efficacy of tocilizumab monotherapy after ultrashort glucocorticoid administration to treat giant cell arteritis: three year follow-up.

Objective: The GUSTO (GCA treatment with Ultra-Short glucocorticoids (GC) and TOcilizumab (TCZ)) trial was set up to evaluate the efficacy and safety of a 52-week TCZ-monotherapy after a 3-day GC-pulse in new-onset GCA. The presented data show the maintenance effect of the GUSTO protocol over 3 years and the effectiveness or retreatment with TCZ after relapse.

Methods: Eighteen patients with newly diagnosed GCA received 500 mg methylprednisolone intravenously for 3 consecutive days followed by TCZ monotherapy from day 3 until week 52 in a single-arm, single-center, open-label clinical trial. Patients in clinical remission stopped TCZ at week 52. Maintenance of efficacy included the proportion of patients with complete lasting remission of disease at week 208.

Results: Median age was 72 (interquartile range 67-75) years at inclusion and 15/18 patients complained of cranial symptoms. At week 52, 13/18 patients were in relapse-free remission and entered the follow-up study. Minor relapses were observed in 2/13 patients at weeks 72, 187 and 200. In both patients, remission was achieved after restart of TCZ monotherapy. At week 208, 11/18 patients stayed in relapse-free remission; 11/13 patients remained in drug-free remission for 156 weeks.

Conclusions: Drug-free remission was maintained in all but two patients entering long-term extension. This relapse rate is substantially lower than reported in the randomized-controlled trials. Patient characteristics (exclusively new diagnoses), and the intensive initial treatment may explain the lasting remission.