This study is open to adults with certain kidney conditions, including secondary focal segmental glomerulosclerosis (sFSGS), treatment-resistant primary minimal change disease (TR-pMCD), Alport Syndrome (AS), and treatment-resistant primary membranous nephropathy (TR-pMN). Adolescents with treatment-resistant primary MCD can also participate in this study. The purpose of this study is to find out whether a medicine called BI 764198 helps people with these kidney conditions.

Participants are put into 2 groups randomly, which means by chance. One group takes BI 764198 tablets, and the other group takes placebo tablets. Placebo tablets look like BI 764198 tablets but do not contain any medicine. Participants take a tablet once a day for 20 weeks. All participants also continue their standard medication for their kidney condition during the study. Participants have twice the chance of being placed in the BI 764198 group than in the placebo group.

Participants are in the study for about 7 months. During this time, they visit the study site 6 times and have 3 phone calls. Doctors regularly test the protein levels in participants' urine by collecting urine samples. They also check kidney function by taking blood samples. The results are compared between the two groups to see whether the treatment works. The doctors also regularly check participants' health and take note of any unwanted effects.

Inclusion Criteria:

• Male or female participants ≥18 years of age (≥12 years of age for Treatment resistant primary Minimal Change Disease (TR-pMCD)) on the day of signing informed consent/assent (Visit 1)

• Body Mass Index (BMI) of ≤40 kg/m2 at screening visit (Visit 1)

• Weight of ≥40 kg at screening

• Estimated glomerular filtration rate (eGFR) ≥25 mL/min/1.73 m2 (chronic kidney disease (CKD) EPI formula based on serum cystatin C) at screening visit

  • For adult participants (≥18); ≥25 mL/min/1.73 m2 (CKD-EPI formula based on serum cystatin C) at the screening visit
  • For adolescent participants (<18); ≥25 mL/min/1.73 m2 (chronic kidey disease under 25 years (CKiD U25) formula using height and serum cystatin C) at the screening visit

• Seated blood pressure (mean of 3 values) systolic blood pressure (SBP) ≤160 mmHg (adult participants ≥18) or SBP ≤140 mmHg (participants <18) at the screening visit (Visit 1). A participant with a documented history of white coat hypertension may be included as long as the participant is considered medically stable by the investigator and "true" blood pressure can be considered to be ≤160 mmHg (adult participants ≥18) or ≤140 mmHg (adolescent participants <18)

• Participants should be treated with angiotensin converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs), at a stable optimised dose for at least 8 weeks prior to the screening visit (Visit 1), with no plan to change the dose until the end of the randomised treatment period (i.e. end of trial (EoT), Week 20) unless not tolerated or indicated as per the discretion of the investigator

• If treated with (non-steroidal) mineralocorticoid receptor antagonist (MRA), endothelin receptor antagonists (ERA), glucagon-like peptide-1 (GLP-1) or Sodium-glucose co-transporter-2 (SGLT2) inhibitors (SGLT2i), participants must be on a stable dose for at least 8 weeks prior to the screening visit (Visit 1), preferably with no plan to change the dose until the end of the randomised double-blind treatment period (i.e. EoT, Week 20)

• Participants treated with oral immunosuppressive therapy except glucocorticoids (e.g. Calcineurin inhibitor(s) (CNI), mycophenolate mofetil/-sodium, cyclophosphamide) must be on a stable dose for at least 12 weeks prior to the screening visit (Visit 1) with no plans to change their dose during the trial treatment period

• Patients treated/to be treated with oral glucocorticoids have to be at a dose ≤10 mg/d prednisolone or equivalent for ≥4 weeks prior to screening with no plan to increase the dose during the treatment period.

Further inclusion criteria apply.

Exclusion Criteria:

• A history of organ transplantation or planned transplantation during the course of the study
• Use of intravenous immunosuppressive agents (e.g. cyclophosphamide, rituximab, obinutuzumab) in the past 6 months prior to screening visit (Visit 1)
• Participants in whom initiation of oral or IV immunosuppression is anticipated during the course of the trial
• Treatment with metformin or dofetilide (multidrug and toxin extrusion protein 1 (MATE1) substrates) within one week prior to randomisation visit (Visit 2) through 5 days after the EoT visit
• Treatment with strong inhibitors or strong inducers of cytochrome P450 3A4/5 (CYP3A4/5) within one week or 5 half-lives (whichever is longer) prior to randomisation visit (Visit 2)
• Alanine aminotransferase (ALT)/aspartate aminotransferase (AST) >3X the upper limit of normal (ULN) at screening visit (Visit 1)
• Clinically significant laboratory abnormalities or medical conditions which pose a safety risk for the participant or may interfere with the trial objectives in the investigator's opinion (except for renal function tests or deviation of clinical laboratory values that are related to the podocytopathy in question) at screening visit
• QTc intervals (QTcF) greater than 450 ms in males or greater than 470 ms in females, or any other clinically relevant ECG findings (at the investigator's discretion) at screening visit (Visit 1) 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.