Sparsentan in Posttransplant Immunoglobulin A Nephropathy or Focal Segmental Glomerulosclerosis (SPARX)

A Multicenter, Open-label Single Arm Study to Evaluate the Safety and Efficacy of Sparsentan in Posttransplant Immunoglobulin A Nephropathy (IgAN) or Focal Segmental Glomerulosclerosis (FSGS) (SPARX)

To evaluate the safety and efficacy of sparsentan tablets for the treatment of patients with proteinuria after kidney transplantation with once-daily dosing for 36 weeks.

Study Overview

• Status: Active, not recruiting
• Conditions: Proteinuria; Focal Segmental Glomerulosclerosis; Kidney Transplant; Immunoglobulin A (IgA) Nephropathy
• Intervention / Treatment: Drug: Sparsentan

Detailed Description

This is a 46-week, open-label, multicenter, single-group Phase 4 study to determine the safety and efficacy of sparsentan for the treatment of patients post kidney transplantation with IgAN or FSGS with proteinuria (≥ 0.5 g/g).

Eligible participants with a kidney transplant receiving stable standard of care (SOC) therapy, including standard immunosuppressive therapy (IST) to prevent graft rejection, will be enrolled to receive sparsentan treatment for 36 weeks. Participants will remain on standard IST for the duration of the study and will stop RAASi prior to initiating sparsentan treatment. The final dose of a RAASi should be taken on the day before the Day 1 visit.

Participants with a kidney transplant, at least one year prior to screening, with biopsy-proven IgAN will take 200 mg orally once daily (QD) for 2 weeks, then 400 mg QD through Week 36. Participants with a kidney transplant with FSGS histological pattern in the graft, or a biopsy finding of both IgAN and glomeruli with FSGS patterns will take 400 mg orally QD for 2 weeks, then 800 mg QD through Week 36.

Study visits will be conducted at Day 5 and Weeks 2, 4, 6, 12, 24, and 36 following Day 1. Following the 36 week treatment period, all participants will complete a 4 week off-sparsentan treatment follow-up period (ie, no study drug), during which time treatment will be at the discretion of the investigator. Participants will have a telephone visit at Week 40.

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Phase 4

Contacts and Locations

Study Locations

• United States
  • Alabama
    • Birmingham, Alabama, United States, 35294
      • University of Alabama at Birmingham
  • New York
    • New York, New York, United States, 10065
      • Cornell Medical Center
  • North Carolina
    • Morrisville, North Carolina, United States, 27560
      • University of North Carolina Chapel Hill
  • Ohio
    • Columbus, Ohio, United States, 43210
      • Ohio State University
  • Texas
    • Dallas, Texas, United States, 75204
      • Dallas Nephrology Associates
    • Galveston, Texas, United States, 27599
      • University of Texas
  • Washington
    • Seattle, Washington, United States, 98195
      • University of Washington
  • Wisconsin
    • Madison, Wisconsin, United States, 53705
      • University of Wisconsin

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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), human immunodeficiency virus (HIV), Hepatitis B and C <3 months prior to and during the screening period.
• Current treatment for surgical complications.
• History of heart failure (New York Heart Association [NYHA] Class II-IV).
• Jaundice, hepatitis, or known hepatobiliary disease.
• Malignancy within the past 2 years with the exception of adequately treated basal cell carcinoma or non-metastatic squamous cell carcinoma of the skin, with no evidence or recurrence.
• History of alcohol or illicit drug use disorder (as defined in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition).
• History of serious side effects or allergic response to any angiotensin II antagonist or ERA.
• Participant requires any of the prohibited concomitant medications.
• Treatment with sparsentan <12 weeks prior to screening.
• Participant has participated in a study of another investigational product <28 days prior to screening or plans to participate in such a study during the course of this study.
• Hematocrit <27%, hemoglobin <90 g/L (9 g/dL), or potassium >5.5 mmol/L (5.5 mEq/L).
• The participant is pregnant, plans to become pregnant during the course of the study, or is breastfeeding.
• The participant, in the opinion of the Investigator, is unable to adhere to the requirements of the study, including the ability to swallow the study IMP whole.
• The participant, in the opinion of the Investigator, has a medical condition or abnormal clinically significant laboratory screening value not listed above that may interfere with the evaluation of sparsentan safety or activity.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Drug: Sparsentan; A non-immunosuppressive single molecule with dual antagonism of ETAR and AT1R, has shown potent anti-proteinuric effect in patients with native kidney disease, including IgAN and FSGS.

Drug: Sparsentan; For participants with a kidney transplant with IgAN: Day 1 through Week 2 visit, participants will take 200 mg once daily (QD) prior to the morning meal. At the Week 2 visit, participants will titrate up to 400 mg QD and take this dose through Week 36, if tolerated and determined to be safe by the Investigator. For participants with a kidney transplant with FSGS, or a biopsy finding of both IgAN and glomeruli with FSGS patterns: Day 1 through Week 2 visit, participants will take 400 mg QD prior to the morning meal. At the Week 2 visit, participants will titrate up to 800 mg QD and take this dose through Week 36, if tolerated and determined to be safe by the Investigator.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Urinary protein/creatinine ratio (UPCR)	Change from baseline (Day 1) in urinary protein/creatinine ratio (UPCR) to Week 36.	36 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline in UPCR	Change from baseline in UPCR each visit.	36 weeks
Urinary albumin/creatinine ratio (UACR)	Change from baseline in UACR at each visit	36 weeks
Change from baseline in eGFR (estimated glomerular filtration rate)	Change from baseline in eGFR, applying creatinine and cystatin C based formulae, at each visit	36 weeks
Achievement of UPCR <0.3 g/g	Achievement of UPCR <0.3 g/g at Weeks 12, 24 and 36	36 weeks
30% and 50% reductions in UPCR	The proportion of participants achieving 30% and 50% reductions in UPCR at Week 36.	36 weeks
Change from baseline in blood pressure (BP)	Change in systolic and diastolic BP at each visit	36 weeks

Collaborators and Investigators

• Sponsor: Travere Therapeutics, Inc.
• Investigators: Study Director: Radko Komers, MD, PhD, Travere Therapeutics

Study record dates

Study Major Dates

• Study Start (Actual): October 7, 2025
• Primary Completion (Estimated): March 1, 2027
• Study Completion (Estimated): May 1, 2027

Study Registration Dates

• First Submitted: October 9, 2025
• First Submitted That Met QC Criteria: October 16, 2025
• First Posted (Actual): October 21, 2025

Study Record Updates

• Last Update Posted (Actual): June 23, 2026
• Last Update Submitted That Met QC Criteria: June 18, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: proteinuria; kidney transplant; FSGS; IgAN
• Additional Relevant MeSH Terms: Urogenital Diseases; Male Urogenital Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urination Disorders; Urological Manifestations; Glomerulonephritis; Nephritis; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Kidney Diseases; Proteinuria; Glomerulosclerosis, Focal Segmental; sparsentan
• Other Study ID Numbers: TVTX-RE021-426

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Requests for clinical trial data, including language stating its intended use, should be directed to datarequest@travere.com. If approved, the requested information will be provided to the requestor after signing a data access agreement. Requests can be made following completion of the study and full publication of the study data in a peer reviewed journal for up to 36 months following its publication. Travere reserves the right to decline or recommend modifications to a request if it does not comply with the data sharing policy or if it is determined that the request is made by a biased source.
• IPD Sharing Time Frame: Requests can be made following completion of the study and full publication of the study data in a peer reviewed journal for up to 36 months following its publication.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No