A Study to Test Whether Different Doses of BI 3000202 Help People With Systemic Lupus Erythematosus (SLE)

Inclusion Criteria:

1. Male and female adult patients from ≥18 years (or alternative age for adults based on local regulations) to \<75 years
2. Confirmed Systemic Lupus Erythematosus (SLE) diagnosis meeting the European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria at least 24 weeks prior to screening
3. At least one of the following positive at screening: Antinuclear Antibodies (ANA) ≥1:80 or anti-double-stranded Deoxyribonucleic Acid (dsDNA) antibody or anti-Smith antibody

   \- Total Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score ≥6 points and clinical SLEDAI-2K score ≥4 points
4. At least 1 British Isles Lupus Assessment Group (BILAG) A and/or 1 BILAG B grade at screening, with sufficient disease activity according to both investigator and adjudicator
5. On SLE background therapy with a maximum of 1 immunosuppressant and/or 1 antimalarial for ≥8 weeks and at a stable dose for ≥4 weeks before screening and/or oral corticosteroids at a dose of ≤30 mg/day prednisone or equivalent, stable for ≥2 weeks before screening (Visit 1) Further inclusion criteria apply.

Exclusion Criteria:

1. Drug-induced SLE
2. Scleroderma (except linear scleroderma that does not interfere with assessments of SLE disease activity) or in the opinion of the investigator or adjudicator elements of other connective tissue disease that would interfere with interpretation of test results or SLE clinical assessments
3. Active or unstable lupus neuropsychiatric manifestations, including but not limited to any condition as defined by BILAG A criteria in the neuropsychiatric system, with the exception of mononeuritis/mononeuropathy multiplex, chorea, and polyneuropathy
4. Lupus nephritis that may require a change in immune-modulating treatment or which demonstrates serum creatinine that is unstable or \>2 × Upper Limit of Normal (ULN) and/or Urine Protein Creatinine Ratio (UPCR) that is unstable or \> 3mg/mg (339 mg/mmol)
5. Oral corticosteroids (prednisone or equivalent) \>30 mg/day at screening Further exclusion criteria apply.