A Study of Rapcabtagene Autoleucel in Systemic Lupus Erythematosus (SLE) Patients With Active, Refractory Lupus Nephritis (LN)

Key Inclusion Criteria:

* Men and women with SLE, aged \>= 18 years and =\< 65 years at screening, fulfilling the 2019 European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) classification criteria for SLE at screening.
* Participant must be positive for at least one of the following autoantibodies at screening: antinuclear antibodies (ANA) at a titer of \>= 1:80 (on HEp-2 cells or an equivalent positive test), or anti-dsDNA (above the ULN); or anti-Sm (above the ULN) as determined by a central laboratory.
* Active lupus nephritis without signs of significant chronicity
* SLEDAI-2K Criteria at screening: SLEDAI-2K score \>= 6 points (Gladman et al 2002, Touma et al 2011), excluding points attributed to "fever", "lupus headache", "alopecia", and "organic brain syndrome".
* Inadequate response at screening to at least two LN treatment regimens

Key Exclusion Criteria:

* Any acute, severe lupus related-flare at screening that needs immediate treatment other than pulse GCs and/or makes the immunosuppressive washout impossible and, thus, makes the participant ineligible for CD19 CAR-T therapy
* Inadequate organ function during screening and prior to randomization
* History or current diagnosis of ECG or cardiac abnormalities indicating significant risk of safety for participants prior to randomization
* Human immunodeficiency virus (HIV) positivity at screening.
* Acute or chronic infection with hepatitis B (HBV) or hepatitis C (HCV) at screening.
* Evidence of active or latent tuberculosis.
* Grade 2 or higher thromboembolic event in the past 4 weeks prior to screening.
* Vaccination (including with live attenuated vaccines) not completed at least 6 weeks prior to randomization.

Other protocol-defined inclusion/exclusion criteria may apply.