A Study to Evaluate the Efficacy and Safety of CC-220 in Subjects With Active Systemic Lupus Erythematosus

The study consists of four phases: * 4-week Screening Phase * 24-week placebo-controlled phase Subjects will receive either 0.45 mg QD, 0.3 mg QD, 0.15 mg QD or placebo for the first 24 weeks of treatment. * 28-week active treatment phase At Week 24, all subjects on placebo will be re-randomized to active treatment. * 52-week long-term extension phase Subjects who complete the treatment phase may be eligible to roll over into a Long-term Extension of up to 52 weeks of treatment. * 4 - 12-week observational follow-up All subjects who complete 52 weeks of treatment or discontinue the study early will enter a post-treatment observation follow-up phase. The Observational Follow-up Phase will consist of one visit 4 weeks following cessation of study drug for all subjects with an additional 12-week Observational Follow-up visit for males only.