Belimumab Assessment of Safety in SLE

Study participants receive standard therapy for SLE in addition to receiving the study drug,
either placebo (no active medicine) or belimumab. The controlled period of the study is 52
weeks. The random assignment in this study is "1 to 1" which means that participants have an
equal chance of receiving belimumab or placebo. After completion of the 52-week study period,
participants will be contacted by phone annually for 4 more years to assess health status.

Following the 52-week controlled period, participants who wish to continue treatment with
belimumab may be able to do so by being prescribed commercially available belimumab. If
belimumab is not commercially available in the participant's country, the participant may be
able to receive belimumab under a separate continuation protocol.

Key Inclusion Criteria:

- Clinical diagnosis of SLE by American College of Rheumatology (ACR) criteria.

- Active SLE disease.

- Autoantibody-positive.

- On stable SLE treatment regimen which may include corticosteroids (for example,
prednisone), antimalarial (for example, hydroxychloroquine) and/or immunosuppressants
(for example, azathioprine, methotrexate, mycophenolate).

Key Exclusion Criteria:

- Pregnant or nursing.

- Have received treatment with any of the following: belimumab, either as a marketed
product or as an investigational agent; any B cell targeted therapy (for example,
rituximab) in the past year; or any biological agent (for example, adalimumab,
etanercept, infliximab, or anakinra) in the past 90 days.

- Have received a live vaccine within the past 30 days.

- Have severe active lupus kidney disease.

- Have severe active central nervous system (CNS) lupus.

- Current or past positive for human immunodeficiency virus (HIV), hepatitis B, or
hepatitis C.