A Study to Evaluate the Efficacy and Safety of CEP-33457 in Participants With Systemic Lupus Erythematosus (SLE)

Inclusion Criteria

• The participant has an established diagnosis of systemic lupus erythematosus (SLE) as defined by ACR Classification Revised Criteria. The diagnosis is fulfilled provided that at least 4 criteria are met.
• The participant has a positive test for antinuclear antibody (ANA) at screening and/or a positive test for anti-double-stranded deoxyribonucleic acid antibody (anti-dsDNA Ab) at screening.
• Women must be surgically sterile, 2 years postmenopausal, or, if of childbearing potential, using a medically accepted method of contraception, and must agree to continued use of this method for the duration of the study and for 30 days after discontinuation of study drug treatment.
• The participant has a clinical SLEDAI-2K score of at least 6 points during screening.
• The participant does not have an "A" score on the BILAG-2004 scale.
• If the patient is using oral corticosteroids, the weekly cumulative dose must not exceed 80 mg of prednisone equivalent; the weekly dose must be stable over the 4 weeks preceding the first dose of study drug.
• If the participant is using antimalarials, methotrexate, leflunomide, mycophenolate mofetil, or azathioprine, the start date must be at least 3 months prior to the first dose of study drug, and the daily dose must be stable over the 4 weeks preceding the first dose of study drug.
• If the participant is not currently using corticosteroids, antimalarials, methotrexate, mycophenolate mofetil, or azathioprine, the last dose (in case of previous use) must be at least 4 weeks prior to the first dose of study drug. For leflunomide, the stop date must be at least 8 weeks before the first dose of study drug, unless an adequate cholestyramine washout has been completed.

Exclusion Criteria

• The participant has been treated with intramuscular or intravenous (iv) pulse steroids (ie, 250 to 1000 milligrams [mg] iv total daily dose of methylprednisolone) within 4 weeks of the first dose of study drug. The use of intra-articular steroids may be allowed after consultation with the medical expert.
• The participant has received tacrolimus, cyclosporine A, or iv immunoglobulins (IVIG) within 3 months of the first dose of study drug.
• The participant has received cyclophosphamide within 12 months prior to the first dose of study drug.
• The participant has been treated for SLE with agents such as fusion proteins, therapeutic proteins, or monoclonal antibodies or antibody fragments, within 12 months of the first dose of study drug.
• The participant has received B-cell depleting agents such as rituximab and has not yet normalized the B-cell count (ie, CD20+ B-cell count is less than 200 and the absolute lymphocyte count [ALC] is less than 1500/μL).
• The participant has New York Heart Association (NYHA) Class III or IV congestive heart failure.
• The participant has severe active lupus nephritis or cerebritis.
• The participant has an estimated glomerular filtration rate (eGFR) of less than 30 milliliters (mL)/minute (min)/1.73 square meter (m^2) (via Modification of Diet in Renal Disease [MDRD] equation).
• The participant has an aspartate aminotransferase (AST) or alanine aminotransferase (ALT) value greater than 2 times the upper limit of normal (ULN) or a total bilirubin level greater than 1.5 times ULN.
• The participant has a planned immunization with a live or live attenuated vaccine within 3 months prior to administration of the first dose of study drug and for 3 months after administration of the last dose of study drug.
• The participant has any clinically significant abnormalities on electrocardiogram (ECG) that are not related to SLE, as determined by the investigator. Participant with stable ECG changes without evidence of active cardiovascular disease may participate at the discretion of the investigator and medical monitor.
• The participant has an ongoing active systemic infection requiring treatment or a history of severe infection, such as hepatitis or pneumonia, in the