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

Inclusion Criteria:

• Diagnosis of GCA defined by the following Revised GCA Diagnosis Criteria:

Age >=50 years. History of ESR >=50 millimeter/hour (mm/hour) or CRP >=2.45 milligram/deciliter(mg/dL).

Presence of at least one of the following: Unequivocal cranial symptoms of GCA; Unequivocal symptoms of polymyalgia rheumatic (PMR).

Presence of at least one of the following: Temporal artery biopsy revealing features of GCA; Evidence of large-vessel vasculitis by angiography or cross-sectional imaging.

• Active GCA within 6 weeks of Randomization (Baseline) where active disease is defined by an ESR >=30 mm/hr or CRP >=1 mg/dL AND the presence of at least one of the following:

Unequivocal cranial symptoms of GCA; Unequivocal symptoms of PMR; Other features judged by the clinician investigator to be consistent with GCA or PMR flares.

• At screening, receiving or able to receive prednisone 20-60 mg/day for the treatment of active GCA.
• Clinically stable GCA disease at baseline such that the subject is able to safely participate in the blinded prednisone taper regimen in the opinion of the investigator.
• Practicing acceptable methods of birth control if a female of child-bearing potential.
• No evidence of active or latent infection with Mycobacterium tuberculosis (TB).

Exclusion Criteria:

• Are pregnant or breastfeeding.
• Recent (within the past 12 weeks) or planned major surgery that would impact on study procedures or assessments.
• Organ transplantation recipients (except corneas within 3 months prior to baseline visit).
• Had prior treatment with any of the following:

Systemic immunosuppressives) within 4 weeks of baseline; Biologic agents targeted at reducing tumor necrosis factor-alpha (TNF-alpha) within 2-8 weeks of baseline, depending on the agent; Any prior use of tocilizumab or other anti-IL-6 agents; B-cell depleting agents (eg, rituximab) within 12 months prior to baseline or longer if B cell counts have not returned to normal range or baseline levels; Cytotoxic drugs such as cyclophosphamide, chlorambucil, nitrogen mustard, or other alkylating agents within 4 weeks of baseline; Abatacept within 8 weeks of baseline; Tofacitinib within 4 weeks of baseline; Methotrexate use within 2 weeks of baseline.

Methylprednisolone > 100 mg/day intravenous (IV) (or equivalent) within 8 weeks of baseline.

• History of severe allergic reactions to monoclonal antibodies, human proteins, or excipients.
• Evidence of serious concomitant disease, which in the opinion of the investigator makes them unsuitable for participation in the study.
• Major ischemic event, unrelated to GCA, within 12 weeks of screening.
• Marked baseline prolongation of corrected QT (QTc) interval >= 450 milliseconds (msec) (QTc by Bazett's formula [QTcB ]or QTc by Fridericia's formula [QTcF] ), history of Torsade de Pointes, family history of long QT syndrome, history of second or third degree heart block.
• Current liver disease that could interfere with the trial
• History of or current active diverticulitis, inflammatory bowel disease, or other symptomatic gastrointestinal tract condition that might predispose to bowel perforation.
• History of known demyelinating diseases such as multiple sclerosis or optic neuritis.
• Active infections, or history of recurrent infections or have required management of acute or chronic infections, as follows:

Currently on any suppressive therapy for a chronic infection, history or suspicion of chronic infection, hospitalization for treatment of infection within 60 days of the baseline visit, or use of parenteral (IV) or intra-muscular [IM]) antimicrobials within 60 days of baseline or oral antimicrobials within 30 days of baseline

• Primary or secondary immunodeficiency or any other autoimmune disease.
• Human immunodeficiency virus (HIV) infection, hepatitis C or hepatitis B infection
• Live virus or bacterial vaccination within 3 months before the first administration of study drug