MPCT-021N, IMPT-514 for SLN and SLE

Inclusion Criteria: 1. Willing and able to provide written informed consent 2. Age 18 years of age or older 3. Weight \> 45 kg at enrollment 4. Adequate blood pressure control 5. On stable background therapy for autoimmune disease (LN, SLE) with stable dose of autoimmune disease medications for at least 4 weeks prior to screening 6. Diagnosis of SLE by 2019 European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) classification criteria or 2012 Systemic Lupus Collaborating Clinics (SLICC) criteria, including positive ANA or positive anti-dsDNA 7. Positive anti-nuclear antibody (ANA), anti-dsDNA (double stranded DNA) or anti-Smith antibody at screening 8. SLE participants: SLEDAI-2K ≥ 6 points, with at least 4 points on clinical, non-laboratory items 9. SLE participants: British Isles Lupus Assessment Group (BILAG) 2004 level B in 2 or more organ systems, or BILAG level A in 1 or more organ system 10. Physician Global assessment ≥ 1 on 0 to 3 visual analogue scale (VAS) 11. LN participants: Active, biopsy-proven, proliferative LN Class III or IV by 2018 International Society of Nephrology/Renal Pathology Society (ISN/RPS) criteria Other protocol-defined criteria apply.

Exclusion Criteria: 1. Any clinically significant underlying illness, other than SLE and LN, which would pose a safety risk or concern, as determined by the Investigator 2. Any other systemic autoimmune condition 3. Rapidly progressive glomerulonephritis 4. Active central nervous system (CNS) lupus 5. History of allogeneic bone marrow or stem cell transplantation or solid organ transplantation 6. History of prior B cell directed cell therapy, including CAR T treatment, autologous or allogeneic, as well as prior bispecific or T cell engager therapy 7. Drug-induced SLE Other protocol-defined criteria apply.