Clinical Study to Investigate the Biological Activity, Safety, Tolerability, and Pharmacokinetics of ACT-334441 in Subjects With Systemic Lupus Erythematosus

International trial to evaluate the biological activity and safety of cenerimod (ACT-334441) in systemic lupus erythematosus (SLE) patients.

Inclusion Criteria: * Male and female participants aged 18 to 65 years with established SLE. Participants must have active SLE, Systemic Lupus Erythematosus Disease Activity Index-2000 (SLEDAI-2K) score of at least 2 points for musculoskeletal or mucocutaneous manifestations and history or presence at screening of positive anti-nuclear antibodies (ANA) or anti-double-stranded DNA (anti-dsDNA) antibodies. * Enrolled participants must be treated with background SLE medications. Exclusion Criteria: * Participants with significant medical conditions or therapies for such conditions (e.g., cardiovascular, pulmonary, immunological, hepatic, ophthalmological, infection and infection risks, history or presence of malignancy, history or presence of bone marrow or solid organ transplantation) or lactating or pregnant women. * Participants with severe SLE disease or with clinically relevant medical or surgical conditions that, in the opinion of the investigator, would put the subject at risk by participating in the study.