An Efficacy and Safety Study of Tocilizumab (RoActemra/Actemra) in Participants With Giant Cell Arteritis (GCA)

This multicenter, randomized, double-blind, placebo-controlled, parallel-group study will evaluate the efficacy and safety of tocilizumab in participants with GCA. The study will consist of 2 parts: a 52-week double-blind treatment period (Part 1) followed by a 104-week open label long-term follow-up period (Part 2). In Part 1 of the study eligible participants will be randomized to receive either tocilizumab every week (qw) or every 2 weeks (q2w) or placebo for 52 weeks, with tapering oral daily doses of prednisone. After Week 52, participants in remission will stop study treatment and enter long-term follow-up, whereas participants with disease activity or flares will receive open-label tocilizumab or other treatment at the discretion of the investigator for a maximum period of 104 weeks.


Eligibility Criteria:
Inclusion Criteria:

* Diagnosis of GCA classified according to age \>/=50 years; history of ESR \>/=50 mm/hr or history of CRP \>/=2.45 mg/dL; and at least one of the following: unequivocal cranial symptoms of GCA or symptoms of polymyalgia rheumatica \[PMR\]; and at least one of the following: temporal artery biopsy revealing features of GCA or evidence of large-vessel vasculitis by angiography or cross-sectional imaging
* New onset (diagnosis within 6 weeks of baseline) or refractory (diagnosis greater than \[\>\] 6 weeks before baseline and previous treatment with \>/= 40 milligrams per day prednisone \[or equivalent\] for at least 2 consecutive weeks at any time) GCA
* Active disease (presence of clinical signs and symptoms \[cranial or PMR\] and ESR \>/=30 mm/hour or CRP \>/=1 mg/dL) within 6 weeks of baseline visit

Exclusion Criteria:

* Major surgery within 8 weeks prior to screening or planned within 12 months after randomization
* Transplanted organs (except corneas with transplant performed \>3 months prior to screening)
* Major ischemic event, unrelated to GCA, within 12 weeks of screening
* Prior treatment with any of the following: investigational agent within 12 weeks (or 5 half-lives of the investigational drug, whichever is longer) of screening; cell-depleting therapies including investigational agent; intravenous (IV) gamma globulin or plasmapheresis within 6 months of baseline; alkylating agents or with total lymphoid irradiation; tocilizumab; hydroxychloroquine, cyclosporine A, azathioprine, or mycophenolate mofetil within 4 weeks of baseline; etanercept within 2 weeks of baseline; infliximab, certolizumab, golimumab, abatacept, or adalimumab within 8 weeks of baseline; anakinra within 1 week of baseline; tofacitinib; cyclophosphamide within 6 months of baseline; \>100 milligrams of daily IV methylprednisolone within 6 weeks of baseline
* Participants requiring systemic glucocorticoids for conditions other than GCA, which, in the opinion of the investigator, would interfere with adherence to the fixed glucocorticoid taper regimen and/or to assessment of efficacy in response to the test article
* History of severe allergic reactions to monoclonal antibodies or to prednisone
* Evidence of serious uncontrolled concomitant disease (for example, cardiovascular, respiratory, renal, endocrine, psychiatric, corneal ulcers/injuries, or gastrointestinal \[GI\] disease)
* Current liver disease, as determined by the investigator
* History of diverticulitis, inflammatory bowel disease, or other symptomatic GI tract condition that might predispose to bowel perforation
* Known active or history of recurrent bacterial, viral fungal, mycobacterial, or other infection
* Primary or secondary immunodeficiency
* Evidence of malignancies diagnosed within previous 5 years (except basal and squamous cell carcinoma of the skin or carcinoma in situ of the cervix uteri that have been excised and cured)
* Inadequate hematologic, renal or liver function
* Positive for hepatitis B or hepatitis C infection