Safety study of AMG 811 in subjects with Systemic Lupus Erythematosus with and without glomerulonephritis

- Men and women, between the ages of 18 and 70 years of age; - Body mass index from 18 to 40 kg/m2 [Body Weight (kg)/Height2 (m2)] at screening; - Diagnosis of SLE at least 6 months before randomization, including a positive antinuclear antibodies (ANA) during screening; if screening ANA is negative, documented historical ANA with a titer of at least 1:80 will be acceptable; - Any concurrent SLE pharmacologic regimen (including mycophenolate mofetil, azathioprine, leflunomide, methotrexate, and anti-malarials) must be stable for at least 30 days before randomization; - Prednisone ≤ 20 mg/day (or equivalent) is permitted; one increase or one decrease of ≤ 5 mg/day prednisone equivalent will be allowed within 30 days before randomization; Additional inclusion criteria for Part B: - Active SLE with GN with no other apparent cause, defined by the following: Renal biopsy evidence (within 18 months) of nephritis using the WHO or International Society of Nephrology (ISN)/Renal Pathology Society (RPS) classification of SLE with GN (Class III or IV); Urine protein/creatinine ratio (UP/Cr) > 1 or 24 hour urine protein > 1g after at least 12 weeks of treatment with mycophenolate mofetil (at least 1.5 grams/day) or azathioprine (at least 100 mg orally per day); Superimposed membranous changes are allowed for those with Class III or Class IV SLE with GN; - Prednisone ≤ 20 mg/day (or equivalent) at the time of randomization.

- Any disorder (including psychiatric), condition or clinically significant disease (other than a diagnosis of SLE) that would, by its progressive nature and/or severity, interfere with the study evaluation, completion and/or procedures per the investigator’s discretion; - Creatinine clearance within the screening period of less than 50 mL/min as calculated by the Cockcroft-Gault method - Signs or symptoms of a viral, bacterial or fungal infection within 30 days of study randomization, or recent history of repeated infections; - Underlying condition other than SLE or being on allowed immunosuppressants that predisposes one to infections - Prior use of the following agents: - Administration of an investigational biologic agent that primarily targets the immune system - Administration of cyclosporine, tacrolimus, sirolimus, IV immunoglobulin, and/or plasmapheresis within 3 months of randomization; - Administration of oral or IV cyclophosphamide (or any other alkylating agent) within 12 months (Part A) or 3 months (Part B) of randomization; - History of ethanol or drug abuse within the last one year prior to randomization; Additional exclusion criteria for Part B: - Rapidly progressive GN (defined as a doubling of serum creatinine within the past 3 months); - Evidence of significant chronicity, defined as: > 50% glomeruli with sclerosis or > 50% interstitial fibrosis on renal biopsy; or International Society of Nephrology (ISN)/Renal Pathology Society (RPS) 2003 Class III (C), IV-S (C) or IV-G (C).