Obe-cel in Severe, Refractory Systemic Lupus Erythematosus With Active Lupus Nephritis

Inclusion Criteria: * Willing and able to give written informed consent for participation in the study or written informed consent signed by a legal guardian or representative * Ability and willingness to adhere to protocol's Schedule of Activities and other requirements * Participants must be 12 to 65 years of age inclusive at the time of signing the informed consent. * Female Participants: - a female participant is eligible to participate if she is not pregnant or breastfeeding * Diagnosis of SLE fulfilling the 2019 European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) Classification Criteria for Systemic Lupus Erythematosus. * Positive for at least 1 of the following autoantibodies: antinuclear antibodies (ANA), or anti-dsDNA or anti-Smith. * Severe, Active SLE defined as: * Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score of ≥ 8 points AND * Severe active LN based on a renal biopsy obtained within 6 months prior to signing the informed consent form or during the screening period Class III, IV or V (V only in combination with class III or IV) * Refractory SLE defined as failure to early lines of therapy and to Calcineurin inhibitors AND B cell-targeting agents Exclusion Criteria: * Any medications prohibited by the protocol. * Prior treatment at any time with anti-CD19 therapy. * More than 1 acute, severe lupus-related flare during screening that needs immediate treatment and/or makes the immunosuppressive washout impossible. * Significant, likely irreversible organ damage related to SLE (e.g., end-stage renal disease) that in the opinion of the Investigator renders CD19 CAR T cell therapy unlikely to benefit the participant. * History of primary antiphospholipid antibody syndrome. * Active or uncontrolled fungal, bacterial, or viral infection * History of malignant neoplasms unless disease free for at least 24 months. * History of heart, lung, renal, liver transplant or hematopoietic stem cell transplant.