This study consists of two periods. The objective of Period 1 is to evaluate the efficacy of an active drug in combination with a 26-week corticosteroid (CS) taper regimen compared to placebo in combination with a 52-week CS taper regimen, as measured by the proportion of participants in sustained remission at Week 52, and to assess the safety and tolerability of an active drug in participants with giant cell arteritis (GCA). The objective of period 2 is to evaluate the safety and efficacy of continuing versus withdrawing the active drug in maintaining remission in participants who achieved remission in Period 1.
50 Years and older.
- Diagnosis of giant cell arteritis (GCA) according to the following criteria:
- History of erythrocyte sedimentation rate (ESR) >= 50 mm/hour or high sensitivity
C-reactive protein (hsCRP)/CRP >=1.0 mg/dL
- Presence of at least one of the following: Unequivocal cranial symptoms of GCA or
Unequivocal symptoms of polymyalgia rheumatica (PMR)
- Presence of 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 such as ultrasound, magnetic resonance imaging (MRI),
computed tomography (CT) or positron emission tomography (PET).
- Active GCA, either new onset or relapsing, within 8 weeks of Baseline.
- Participants must have received treatment with >=40 mg prednisone (or equivalent) at
any time prior to Baseline and be receiving prednisone (or equivalent) >= 20 mg once
daily (QD) at Baseline.
- Participants must have GCA that, in the opinion of the investigator, is clinically
stable to allow the participant to safely initiate the protocol-defined corticosteroid
(CS) taper regimen.
- Females must either be postmenopausal or permanently surgically sterile or, practicing
at least 1 specified method of birth control through the study.
- Prior exposure to any Janus Kinase (JAK) inhibitor.
- Treatment with an interleukin-6 (IL-6) inhibitor within 4 weeks of study start, or
prior treatment with an IL-6 inhibitor and experienced a disease flare during
- Use of any of the following systemic immunosuppressant treatments within the specified
timeframe prior to study start:
- Anakinra within 1 week of study start.
- Methotrexate, hydroxychloroquine, cyclosporine, azathioprine, or mycophenolate
within 4 weeks of study start.
- Oral corticosteroid (CS) for conditions other than GCA within 4 week of study
start, or intravenous CS within 4 weeks of study start.
- Greater than or equal to 8 weeks for leflunomide if no elimination procedure was
followed, or adhere to an elimination procedure.
- Cell-depleting agents or alkylating agents including cyclophosphamide within 6
months of study start.
- Current or past history of infection including herpes zoster or herpes simplex, human
immunodeficiency virus (HIV), active Tuberculosis, active or chronic recurring
infection, active hepatitis B or C.
- Female who is pregnant, breastfeeding, or considering pregnancy during the study.