Sparsentan in Posttransplant Immunoglobulin A Nephropathy or Focal Segmental Glomerulosclerosis

Inclusion Criteria: * Willing and capable of giving signed informed consent which includes compliance with the requirements and restrictions listed in the ICF and in the protocol. * Male and female aged ≥18 years * Participants with a kidney transplant with biopsy-proven IgAN or FSGS histological pattern in the graft. * A period of ≥12 months since kidney transplantation. * UPCR ≥0.5 g/g and eGFR (CKD-EPI creatinine-based formula ≥30 mL/min/1.73 m2. * Participants who can become pregnant, must agree to the use of 1 highly reliable method of contraception from 7 days prior to the first dose of study intervention until 30 days after the last dose of study intervention. * Systolic BP ≤160 mmHg and ≥100 mmHg, and diastolic BP ≤100 mmHg and ≥60 mmHg at screening. * For participants on an ACEI and/or ARB, and/or sodium glucose cotransporter-2 (SGLT2) inhibitor, the dosing regimen(s) is stable for ≥6 weeks prior to screening. Exclusion Criteria: * Participant has multiorgan transplants (with the exception of pancreas and corneal transplants). * Immunosuppressive therapy (IST) regimen for kidney transplant or other systemic chronic ISTs including enteric budesonide that is not stable for \>6 weeks prior to Day 1. Exceptions include routine changes in the dose of CNIs to meet target level. * \<3 months after antirejection treatment and active rejection. * Active bacterial, fungal or viral infection and/or active treatment of infection including BK virus (BKV), cytomegalovirus (CMV)…