Belimumab Treatment Holiday and Treatment Re-start Study in Lupus Patients

This study will assess the effect of a 24-week withdrawal of belimumab followed by a 28-week
reintroduction of belimumab 10 mg/kg plus standard of care medications on immunogenicity,
markers of biological activity, efficacy, and safety in subjects with stable low systemic
lupus erythematosus (SLE) disease activity. Additionally, this study will assess rebound
phenomenon in subjects with any disease level of SLE who have permanently withdrawn from
further belimumab treatment

Inclusion Criteria:

- Received a minimun of 6 months therapy with with belimumab 10 mg/kg in their current
SLE belimumab continuation study.

- Be 18 years of age at the Day 0 visit.

- Non-prenant, non-lactating females willing to comply with specific birth control
requirements as set forth in the protocol.

- Able to provide written informed consent to participate.

- Subjects who wish to enroll in the control group and the group taking a 6 month
belimumab treatment holiday will need a SELENA SLEDAI score of 3 or less after the
minimum of 6 months belimumab therapy, as well as having C3 and C4 complement levels
at or above the lower limit of the central laboratory reference range, and are on a
stable SLE treatment regimen during the 30 day screening period prior to Day 0.

- Subjects who wish to enroll in the long-term discontinuation group have voluntarily
withdrawn from their continuation studies.

Exclusion Criteria:

- Subjects who have developed clinical evidence of significant, unstable or
uncontrolled, acute or chronic diseases not due to SLE, or experienced an adverse
event (AE) in their belimumab continuation study that could, in the opinion of the
principle investigator, put the subject at undue risk.

- Subjects who have developed any other medical diseases, laboratory abnormalities, or
conditions that, in the opinion of the principle investigator, makes the subject
unsuitable for the study.