A Study to Evaluate the Effect of Belimumab on Vaccine Responses in Subjects With Systemic Lupus Erythematosus (SLE)

All patients in this study will receive belimumab plus standard therapy for SLE and
vaccination against pneumococcus. Patients will be randomized to receive pneumococcal
vaccination either 4 weeks prior (early vaccination group) or 24 weeks after (late
vaccination group) their first belimumab dose. Vaccine response will be assessed 4 weeks
after vaccine administration.

Key Inclusion Criteria:

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

- Active SLE disease.

- Autoantibody-positive.

- Have antibodies with titers >1.0 microgram (mcg)/mL to no more than 9 of the 23
serotypes present in the pneumococcal vaccine.

- Have the ability to understand the requirements of the study, provide written informed
consent, and comply with the study protocol procedures.

Key Exclusion Criteria:

- Pregnant or nursing.

- Have received any prior treatment with belimumab.

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

- Have received a pneumococcal vaccination with the past 5 years.

- Have a history of severe allergic reaction to a vaccine, contrast agents (such as
those used for x-rays and CT scans), or biological medicines.

- Have required management of an infection or have had infections that keep coming back
within the past 60 days.

- Hepatitis B: Serologic evidence of Hepatitis B (HB) infection based on the results of
testing for HB surface antigen (HBsAg) and anti-HB core antibody (anti-HBc):

- Subjects positive for HBsAg are excluded.

- Subjects negative for HBsAg but positive for anti-HBc, regardless of anti-HBs
antibody status, are excluded.

- Hepatitis C: Positive test for Hepatitis C antibody.

- Known human immunodeficiency virus (HIV) infection.

- Have current drug or alcohol abuse or dependence.

- Have a Grade 3/4 immunoglobulin (Ig)G deficiency (IgG level <400 milligrams [mg]/
deciliter [dL]) or IgA deficiency (IgA level <10 mg/dL).

- Subjects who have evidence of serious suicide risk including any history of suicidal
behavior in the last 6 months and/or suicidal ideation with some intent to act in the
last 2 months or who in the investigator's judgment, pose a significant suicide risk.