The goal of this clinical trial is to assess the efficacy and safety of extended TARPEYO® (delayed-release budesonide capsules) treatment in adult patients with primary IgA nephropathy who have completed 9 months of TARPEYO® 16 mg once daily treatment in real-world clinical practice. The main question it aims to answer is:

Is there a treatment benefit of TARPEYO® 16 mg QD extended use?

Participants will

• take part in this study for about 19 months
• Have urine tests done
• Have blood samples taken
• Have physical examinations done

This clinical trial will investigate the efficacy and safety of TARPEYO® treatment extended for an additional 15 months in adult IgAN participants who have completed their initial, single 9-month TARPEYO® 16 mg QD commercial treatment regimen. Participants with residual proteinuria will be eligible for enrollment. The Treatment Period will consist of a 6-month Treatment Period with TARPEYO® 16 mg QD, followed by a 9-month Treatment Period with TARPEYO® 8 mg QD. This will be followed by a 3-month Follow-up Period, which includes the first 2 weeks of Tapering Period with TARPEYO® 4 mg QD.

The overall aim of the extended treatment is to improve and maintain the treatment effect with reduced proteinuria and protection of kidney function over a total of 2 years of TARPEYO® treatment.

Inclusion Criteria:

1. Diagnosed IgAN with biopsy verification
2. Female or male participants ≥18 years of age
3. Completion of a single, initial 9 months of treatment with TARPEYO® 16 mg QD at the Baseline visit
4. Access to retrospective local laboratory assessment data on UPCR and serum creatinine. Available retrospective data should include at least 1 assessment timepoint within 3 months prior to the first dose of TARPEYO® commercial treatment.
5. On stable treatment with renin-angiotensin system (RAS) inhibitor therapy or sparsentan for at least 8 weeks prior to the Baseline visit. A stable dose is defined as a dose within 25% of the dose at Baseline.
6. If on current treatment with sodium-glucose cotransporter-2 (SGLT2) inhibitor, the treatment should have been stable for at least 8 weeks prior to the Baseline visit. A stable dose is defined as a dose within 25% of the dose at Baseline.

Exclusion Criteria:

1. Participants who have been treated with systemic immunosuppressive medications including glucocorticosteroids (GCS) other than TARPEYO® during the TARPEYO® commercial treatment period. Topical or inhalation products containing GCS or immunosuppressants are allowed.
2. Presence of other glomerulopathies (e.g., C3 glomerulopathy, diabetes nephropathy and/or hypertensive nephropathy).
3. Presence of nephrotic syndrome (i.e., proteinuria >3.5 g per day and serum albumin <3.0 g/dL, with or without edema).
4. Presence of medical condition excluding continued TARPEYO® treatment, as assessed by the Investigator.
5. On current or planned dialysis.
6. Undergone kidney transplant.
7. Poorly controlled diabetes mellitus or hypertension, as assessed by the Investigator.
8. Participants with known osteoporosis in the medium- or high-risk category according to the 2010 American College of Rheumatology recommendations.
9. Any medical or social circumstance making trial participation and/or TARPEYO® treatment unsuitable, as assessed by the Investigator.
10. Participants with clinically significant infections that put the participant at risk, at the discretion of the Investigator.
11. Participants unwilling or unable to meet the requirements of the protocol.
12. Intake of another investigational drug during trial, or during the preceding 9-monthcommercial TARPEYO® treatment period.
13. Females who are pregnant, breastfeeding, or plan to become pregnant in the trial period.
14. Participants taking potent inhibitors of cytochrome P450 (CYP) 3A4