• Signed informed consent must be obtained prior to participation in the study; participants should be able to communicate well with the investigator, understand and comply with the requirements of the study.

• Male and female participants ≥18 years of age with biopsy-confirmed IgA nephropathy and an eGFR ≥ 30 mL/min/1.73m2. eGFR will be calculated using the CKD-EPI 2009 formula.

• Proteinuria as assessed at screening by UPCR ≥ 0.8g/g or 1g/d sampled from FMV.

• Biopsy at baseline should confirm IgAN with \< 50% tubulointerstitial fibrosis.

• Participants must be on ACEi or ARB treatment at either the locally approved maximal daily dose or the maximally tolerated dose (per investigators' judgment) for approximately 90 days prior to baseline visit and continue on a stable dose throughout the study. Participants with allergies or intolerance to ACEi and ARB are eligible for the study, but the investigator should clearly document the reasons for not being on maximal ACEi/ARB dose in the source documents. In addition, if participants are taking diuretics, other antihypertensive medication or Sodium-Glucose Co-Transporter 2 inhibitors (SGLT2i), the doses should be stabilized for at least 90 days prior to baseline.

• Vaccination against Neisseria meningitidis and Streptococcus pneumoniae infections required to be completed at least 2 weeks prior to the start of study treatment. If the participants have not been previously vaccinated, or if a booster is required, vaccine should be given according to local regulations at least 2 weeks prior to first study drug administration. If study treatment must start earlier than 2 weeks post-vaccination, prophylactic antibiotic treatment should be initiated.

• Vaccination against Haemophilus influenzae infection should be given, if available and according to local regulations, at least 2 weeks prior to first study drug administration.