Tofacitinib as a GC Sparing Agent for Polymyalgia Rheumatica

Inclusion Criteria: 1. Female or male between 50 and 85 years old. 2. PMR according to the ACR/ EULAR 2012 PMR classification criteria. 3. Patients must have erythrocyte sedimentation rate (ESR) ≥20 mm/hr and/or CRP ≥8 mg/L associated with highly active PMR (PMR-AS\>17) within 2 weeks prior to screening. 4. Patient is willing and able to take prednisone of 15 mg/day at baseline. 5. Signed written informed consent. Exclusion Criteria: 1. Presence of any other connective tissue disease, such as but not limited to giant-cell arteritis, systemic lupus erythematosus, systemic sclerosis, vasculitis, myositis, mixed connective tissue disease, and ankylosing spondylitis. 2. Concurrent diagnosis of active fibromyalgia, rhabdomyolysis or neuropathic muscular diseases. 3. Organ transplant recipient. 4. Any prior (within the defined period below) or concurrent use of immunosuppressive therapies but not limited to any of the following: ① Any prior use of tumor necrosis factor inhibitors, anti-IL-6 agents or JAK inhibitor; ② Alkylating agents including cyclophosphamide within 6 months of baseline; ③ Cell-depletion agents (e.g. anti-CD20) without evidence of recovery of B cells to baseline level; ④ Abatacept within 8 weeks of baseline; ⑤ Any prior use of csDMARDs at unstable dose for less than 12 weeks before baseline, e.g. cyclosporine, azathioprine, mycophenolate mofetil, leflunomide, MTX; ⑥ Concurrent use of systemic GCs for conditions other than PMR. 5. Evidence (as assessed by the investigators) of active infection, such as presence of hepatitis B surface antigen (HBsAg) or hepatitis C antibody in blood, human immunodeficiency virus (HIV) positivity. 6. Patients with a history of active or recurrent herpes zoster. 7. Patients who have had surgery within 4 weeks of screening or planned surgery during study. 8. Malignancy within 5 years prior to screening, except for non-melanoma skin cancer. 9. Pregnant or breastfeeding woman. 10. Any medical condition that could interfere with the implementation or interpretation of the study or with the safety of the patient during the study.