351. EFFECTS OF BASELINE PREDNISONE DOSE ON REMISSION AND DISEASE FLARE IN PATIENTS WITH GIANT CELL ARTERITIS TREATED WITH TOCILIZUMAB IN A PHASE 3 RANDOMIZED CONTROLLED TRIAL

Abstract

Background: Adding tocilizumab (TCZ) to tapered prednisone treatment for patients with giant cell arteritis (GCA) leads to improved rates of sustained glucocorticoid‐free remission [1]. It is not known, however, whether the glucocorticoid dose at initiation of TCZ affects disease control. We investigated sustained remission and disease flare according to baseline (BL) prednisone doses in patients with GCA treated with TCZ or placebo (PBO) and scheduled prednisone tapering in the GiACTA trial [1]. Methods: Patients received TCZ‐weekly or ‐every‐other‐week + 26‐week prednisone taper (TCZ‐QW [n = 100] or TCZ‐Q2W [n = 49]) or placebo + 26‐week or 52‐week prednisone taper (PBO+26 [n = 50] or PBO+52 [n = 51]) for 52 weeks [1]. Flare was defined as recurrence of signs or symptoms of GCA and/or ESR >30 mm/h attributable to GCA requiring increased prednisone dose. Sustained remission was defined as absence of flare, normalization of CRP (<1 mg/dL), and adherence to the protocol‐defined prednisone taper to week All patients received prednisone during screening at a dose selected by the investigator before entry to the trial. In this post hoc analysis, sustained remission rates were assessed according to BL prednisone dose, and time to first flare was assessed according to protocol‐defined BL prednisone dose stratification factors (>30 mg/day or < 30 mg/day). All analyses are descriptive. Results: Sustained remission was achieved by higher proportions of patients in the TCZ groups than the PBO groups across the range of BL prednisone doses (Figure 1). Kaplan‐Meier analysis of time to flare demonstrated that among patients with high BL prednisone doses (>30 mg/day), TCZ‐treated patients had longer time to flare than those in the PBO groups. Patients with low BL prednisone doses (<30 mg/day) had separation between the TCZ groups and the PBO+26 group from week 12, with longer time to flare in the TCZ and PBO+52 groups than in the PBO+26 group. In the PBO+26 group, patients with low BL prednisone doses flared earlier than patients with high BL doses, but there was no apparent difference in time to flare between high and low BL prednisone dose for the TCZ groups. Conclusion: Patients with GCA treated with TCZ and prednisone tapering could achieve sustained remission across a range of BL prednisone doses. Fewer patients in the TCZ groups than the PBO groups had GCA flares. Time to flare was similar for patients treated with TCZ regardless of starting prednisone dose.