Study of EQ001 (Itolizumab) in Systemic Lupus Erythematosus With or Without Active Proliferative Nephritis

Type A Cohort Key Inclusion Criteria: 1. Is male or female, age ≥ 18 and ≤ 75 years 2. Has previously been documented to have met or currently meets Systemic Lupus International Collaborating Clinics (SLICC) and/or American College of Rheumatology (ACR) criteria for SLE 3. Received at least 1 immunosuppressive or immunomodulatory treatment for SLE at any time in the past or currently 4. Has documented elevation of antinuclear antibodies (ANA) in the past or during Screening 5. Restricted SLE treatments are stable and/or washed out 6. During Screening, has adequate hematologic function Type B Cohort Key Inclusion Criteria: 1. Is male or female, age ≥ 18 and ≤ 75 years 2. Has a diagnosis of SLE 3. Kidney biopsy with a histologic diagnosis of LN Classes III or IV (+/- V) 4. Has a urine protein to creatinine ratio of \> 1000 mg/g 5. Requires induction treatment due to newly diagnosed LN or relapsing/flaring disease or has an incomplete response to current treatment 6. Has adequate hematologic function 7. Restricted SLE treatments are stable and/or washed out 8. Most recent eGFR ≥ 40 mL/min/1.73m2 9. Has evidence of serologic activity Key Exclusion Criteria: 1. Acute or chronic infections requiring systemic antibacterial, antifungal, or antiviral therapy 2. Positive for hepatitis B virus (HBV), hepatitis C virus (HCV), or HIV 3. Active TB or a positive TB test