During a safety review of studies U2970g and U2971g, the Data Monitoring Committee recommended that enrollment in this extension trial be terminated.

This is a Phase II/III open label, single-arm, multicenter, extension study to evaluate the safety and efficacy of rituximab when administered on a scheduled basis every 6 months over the course of 1 year with reassessment of response at 12 months. This study is open to participants previously enrolled in Genentech Study U2971g only.

Inclusion Criteria:

• Subjects with systemic lupus erythematosus (SLE) who participated and satisfactorily completed their Week 52 evaluation in Study U2971g.
• For partial clinical response (PCR) or nonclinical response (NCR), active disease at screening as defined by one or more domains with a British Isles Lupus Assessment Group (BILAG) A score or 2 or more domains with a BILAG B score.

Exclusion Criteria:

• Subjects who were withdrawn from study U2971g because of protocol non-compliance or for safety issues.
• Any safety concern potentially attributed to rituximab that in the investigator's opinion would jeopardize subject safety.
• Subjects who were withdrawn from study U2971g and received rituximab rescue therapy outside of the protocol.
• Subjects, that in the investigator's opinion, have not demonstrated any clinical improvement by Week 52 in study U2971g and in whom the proposed therapy would represent risk without benefit.
• Unstable subjects with thrombocytopenia experiencing or at high risk for developing clinically significant bleeding or organ dysfunction requiring therapies such as plasmapheresis or acute blood or platelet transfusions.
• Pregnant women or nursing (breastfeeding) mothers.
• History of severe, allergic, or anaphylactic reactions to humanized or murine monoclonal antibodies.
• Known active infection of any kind (excluding fungal infection of nail beds) or any major episode of infection requiring hospitalization or treatment with intravenous (IV) antibiotics within 8 weeks of screening or oral antibiotics within 2 weeks prior to screening.
• History of cancer, including solid tumors, hematological malignancies, and carcinoma in situ.
• Major surgery within 4 weeks prior to screening.
• Intolerance or contraindication to oral or IV corticosteroids.
• Positive hepatitis B surface antigen (BsAg) or hepatitis C serology.
• Receipt of a live vaccine within 28 days prior to treatment.

The Study being conducted under this Agreement is part of the Overall Study. Investigator is free to publish in reputable journals or to present at professional conferences the results of the Study, but only after the first publication or presentation that involves the Overall Study. The Sponsor may request that Confidential Information be deleted and/or the publication be postponed in order to protect the Sponsor's intellectual property rights.