This study is open to adults with systemic lupus erythematosus (SLE). The purpose of this study is to find out whether a medicine called BI 3000202 helps people with SLE. The study tests different doses of BI 3000202 and aims to find the best dose for people with this condition.

Participants are put into 5 groups randomly, which means by chance. 4 groups get different doses of BI 3000202, and 1 group gets a placebo. Placebo tablets look like BI 3000202 tablets but do not contain any medicine. Participants take the tablets for 1 year. All participants also continue their regular treatment for SLE.

Participants are in the study for a bit longer than 1 year. During this time, they visit the study site regularly. Doctors check the participants' health and take note of any unwanted effects. They also compare the results between the groups to see if the treatment works.

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.

Once the criteria in section "Time Frame" are fulfilled, researchers can use the following link https://www.clinicalstudies.boehringer-ingelheim.com/msw/datasharing to request access to the clinical study documents regarding this study, and upon a signed "Document Sharing Agreement".

Furthermore, researchers can request access to the clinical study data, for this and other listed studies, after the submission of a research proposal and according to the terms outlined in the website.

One year after the approval has been granted by major Regulatory Authorities and after the primary manuscript has been accepted for publication, or after termination of the development program.

For study documents - upon signing of a "Document Sharing Agreement". For study data - 1. after the submission and approval of the research proposal (checks will be performed by the sponsor and/or the independent review panel, including checking that the planned analysis does not compete with sponsor's publication plan); 2. and upon signing of a legal agreement.