A Study of the Effect and Safety of Sparsentan in the Treatment of Patients With IgA Nephropathy

This is a randomized, multicenter, double-blind, parallel-group, active-control study.
Approximately 280 patients aged ≥18 years will be enrolled in the study globally. The
investigational drug (sparsentan) is a dual acting angiotensin receptor blocker and
endothelin receptor antagonist. The active control is irbesartan.

The purpose of the study is to evaluate the potential benefit of sparsentan on kidney
function by analyzing change in proteinuria (protein in urine) and estimated glomerular
filtration rate (eGFR) as compared to current standard treatment.

Patients enrolled in the PROTECT study (Protocol 021IGAN17001) will be those at high risk of
progressing to renal failure. They will be randomly assigned n a 1:1 ratio to either
sparsentan or irbesartan, as the active control (current standard treatment) at the Day 1
(Randomization) visit. Study medication (sparsentan and irbesartan) will be administered as a
single oral morning dose.

The primary analysis is change in proteinuria (urine protein/creatinine ratio) from baseline
at Week 36 in sparsentan-treated patients as compared to irbesartan-treated patients.

Key Inclusion Criteria:

- Age 18 years or older at screening

- Biopsy-proven primary IgAN

- Proteinuria of >=1 g/day at screening

- eGFR >=30 mL/min/1.73 m2 at screening

- Currently on stable dose of ACEI and/or ARB therapy, for at least 12 weeks prior to
screening (maximum tolerated dose and at least one-half of the maximum labeled dose)

- Systolic BP <=150 mmHg and diastolic BP <=100 mmHg at screening

- Agree to contraception

Key Exclusion Criteria:

- IgAN secondary to another condition

- Presence of cellular glomerular crescents in >25% of glomeruli on renal biopsy (if
biopsy available within 6 months of screening)

- History of type 1 diabetes mellitus, uncontrolled type 2 diabetes mellitus (HbA1c
>8%), or nonfasting blood glucose >180 mg/dL at screening

- History of organ transplantation, with exception of corneal transplants

- Require any prohibited medications

- Treatment of systemic immunosuppressive medications (including corticosteroids) for >2
weeks within 3 months of screening

- History of heart failure or previous hospitalization for heart failure or unexplained
dyspnea, orthopnea, paroxysmal nocturnal dyspnea, ascites, and/or peripheral edema

- Clinically significant cerebrovascular disease or coronary artery disease within 6
months of screening

- Jaundice, hepatitis, or known hepatobiliary disease or elevations of transaminases
(ALT/AST) >2 times upper limit of normal at screening

- History of malignancy other than adequately treated basal cell or squamous cell skin
cancer or cervical carcinoma within the past 2 years

- Hematocrit value <27% or hemoglobin value <9 g/dL at Screening

- Potassium >5.5 mEq/L at Screening

- History of alcohol of illicit drug use disorder

- History of serious side effect or allergic response to any angiotensin II antagonist
or endothelin receptor antagonist, including sparsentan or irbesartan, or has a
hypersensitivity to any of the excipients in the study medications

- For female: Pregnancy, or planning to become pregnant during the course of the study,
or breastfeeding

- For male: planning to father a child during the course of the study

- Participation in a study of another investigational product within 28 days of
screening