Efficacy and Safety Study of Sirukumab in Patients With Giant Cell Arteritis

Sirukumab is a fully human anti-interleukin-6 (IL-6) immunoglobulin G1-kappa with a high affinity and specificity for binding to the human IL-6 molecule that may have therapeutic benefit in the treatment of giant cell arteritis (GCA) by interruption of multiple pathogenic pathways. Sirukumab inhibits IL-6-mediated signal transducer and activator of transcription 3 (STAT3) phosphorylation, resulting in the inhibition of the biological effect of IL-6. This study will evaluate the efficacy and safety of sirukumab to characterize the benefit-to-risk profile of sirukumab in the treatment of active GCA. The study will be conducted in 2 distinct parts (Part A and Part B) and consists of the following phases: Screening phase, Part A: 52-week double-blind treatment phase, Part B: 104-week extension phase with the option to receive open-label sirukumab based on disease status and a 16-week follow-up phase if applicable. Approximately 204 subjects with a diagnosis of GCA and active disease within 6 weeks of baseline will be randomized into Part A, the 52-week double-blind treatment phase, to receive one of two doses of sirukumab or placebo, each in addition to a pre-specified prednisone taper. The efficacy and safety of sirukumab in sustaining remission will be assessed at Week 52. Subjects completing Part A of the study will be eligible to enter Part B, the 104-week extension phase, designed to investigate the long-term maintenance of remission and safety following cessation of sirukumab treatment and to assess long-term corticosteroid use. Subjects with active GCA at the end of Part A or those with new onset of GCA flare during the first 52 weeks of Part B will be eligible to receive open-label sirukumab. Subjects will need to have follow-up safety evaluations for at least 16 weeks after receiving the last dose of study drug, applicable only for those who are withdrawn prematurely from the study or whose open-label sirukumab treatment in Part B completes after Week 88.