A Study to Evaluate Efficacy and Safety of Subcutaneous Abatacept With Steroid Treatment Compared to Steroid Treatment Alone in Adults With Giant Cell Arteritis (GCA)

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Inclusion Criteria:

- New headache (new onset or new type of localized pain in the head)

- Elevated ESR (≥ 50 mm/h by the Westergren method) or CRP ≥ 1 mg/dL

- Temporal artery abnormality (i.e. temporal artery tenderness to palpation or
decreased pulsation, unrelated to arteriosclerosis of cervical arteries)

- Temporal artery biopsy showing vasculitis characterized by a predominance of
mononuclear cell infiltration or granulomatous inflammation, usually with
multinucleated giant cells

- Large vessel biopsy showing vasculitis characterized by a predominance of mononuclear
cell infiltration or granulomatous inflammation, usually with multinucleated giant
cells or characteristic changes of large vessel stenosis or aneurysm secondary to GCA
as seen by arteriography (Magnetic Resonance Imaging/ Magnetic Resonance
Angiography), ultrasound (eg, halo sign on color duplex sonography), or CT scan

- Patients must be treated with prednisone or prednisolone of 20-60 mg/day (prednisone
equivalent) and be on a dose between 20-60 mg/day for at least 2 weeks prior to
enrollment into the study

Exclusion Criteria:

- Rheumatic disease other than GCA such as Takayasu's Arteritis, granulomatosis with
polyangiitis (Wegener's), rheumatoid arthritis, systemic lupus erythematosus

- Patients with unilateral blindness (partial or complete) or who have unstable or
recurrent visual symptoms attributable to GCA within 4 weeks of randomization

- Patients with a history of dissection of aorta

- Patients with a history of myocardial infarction, stroke or transient ischemic attack
attributable to GCA within the 3 months of screening

- Patients who have been treated with intravenous ("pulse") doses of glucocorticoids
defined as methylprednisolone > 1000 mg/day if given within 6 weeks of randomization

- Patients who will require oral or IV glucocorticoid treatment during the trial for
conditions other than GCA

- Patients at risk of tuberculosis

Other protocol defined inclusion/exclusion criteria could apply