Long-term Safety and Tolerability of Cenerimod in Adults With Systemic Lupus Erythematosus

The goal of this clinical study is to learn about the long-term safety and tolerability of cenerimod in adult patients with moderate to severe symptoms of systemic lupus erythematosus. The main questions it aims to answer are: * Whether cenerimod causes any adverse effects ('side effects') when given on top of drugs already being given for systemic lupus erythematosus. * How well cenerimod works to reduce symptoms of systemic lupus erythematosus when taken for at least 1 year and up to 3 years. Participants taking part in this study will have already taken part in another study, where they received either cenerimod or placebo (look-alike substance containing no active drug) for 1 year. In this clinical study approximately 680 participants will receive cenerimod (on top of drugs already being given for systemic lupus erythematosus) for at least 1 year and up to 3 years.

Inclusion Criteria: 1. Signed and dated informed consent form prior to any study-mandated procedure. 2. Participants with a diagnosis of systemic lupus erythematosus who: * Completed the 12-month double-blind treatment period of either of the parent studies (ID-064A301, ID-064A302). * Did not meet any study treatment stopping criteria during the parent study. * Completed the last scheduled visit of the parent study. Participants who did not complete the last scheduled visit for reasons beyond their control may be eligible for this study upon approval by the sponsor. 3. Women of child-bearing potential: * Negative pregnancy test at Visit 1. * Agreement to undertake monthly urine pregnancy tests from Visit 2 up to 6 months after study treatment discontinuation. * Agreement to use a highly effective method of contraception from Visit 1 up to 6 months after study treatment discontinuation. Exclusion Criteria: 1. Poor compliance with study-mandated procedures during the parent study (ID-064A301 or ID-064A302), e.g., took less than 80% of the planned doses of double-blind study treatment; or did not attend a majority of the site visits, unless there was a medically justified reason as judged by the investigator. 2. Systemic lupus erythematosus driven renal disease, central nervous system lupus, or active severe or unstable neuropsychiatric systemic lupus erythematosus where, in the judgment of the investigator, protocol-specific systemic lupus erythematosus background therapy is insufficient, and the use of a more aggressive therapeutic approach or other treatments not permitted in the protocol is indicated. 3. Women of child-bearing potential planning to become pregnant up to the final study visit. 4. Judged not eligible to participate by the investigator, for any other reason. 5. Confirmed active or latent tuberculosis (applicable only if requested by local regulations).