Inclusion Criteria: - Diagnosis of SLE defined as follows: - Fulfilling the 2019 ACR/EULAR classification criteria of SLE - Presence of anti-dsDNA, anti-histone, anti-chromatin, or anti-Sm antibodies - SLE disease activity - Active disease at screening, defined as ≥ 1 major organ system with a BILAG A score (excluding musculoskeletal, mucocutaneous, and/or constitutional organ system) - ii) Inadequate response to glucocorticoids and to at least 2 of the following treatments, used for at least 3 months each: cyclophosphamide, mycophenolic acid or its derivatives, belimumab, azathioprine, anifrolumab, methotrexate, rituximab, obinutuzumab, cyclosporin, tacrolimus or voclosporin. i) Insufficient response is defined as lack of response, insufficient response or lack of sustained response to appropriate doses. Intolerance is not considered insufficient response ii) Methotrexate and azathioprine use will count as 1 for the purposes of the number of failed treatments. Exclusion Criteria: - Diagnosis of drug-induced SLE rather than idiopathic SLE - Other systemic autoimmune diseases (eg, multiple sclerosis, psoriasis, inflammatory bowel disease, etc) are excluded. Participants with type I autoimmune diabetes mellitus, thyroid autoimmune disease, Celiac disease, or secondary Sjögren's syndrome are not excluded - SLE overlap syndromes including, but not limited to, rheumatoid arthritis, scleroderma, and mixed connective tissue disease, are excluded - Recent or present clinically significant CNS pathology Other protocol-defined Inclusion/Exclusion criteria apply.