The U.S. Food and Drug Administration (FDA) has accepted Travere Therapeutics' supplemental New Drug Application (sNDA) for traditional approval of sparsentan (Filspari) for the treatment of focal segmental glomerulosclerosis (FSGS). The regulatory agency has set a Prescription Drug User Fee Act (PDUFA) target action date of January 13, 2026.
The FDA has also indicated plans to convene an advisory committee meeting to discuss the application, highlighting the significance of this potential treatment option for patients with FSGS, a rare kidney disorder characterized by scarring in the kidney's filtering units.
Sparsentan's Therapeutic Potential for FSGS
Sparsentan is a novel dual endothelin angiotensin receptor antagonist (DEARA) that targets two critical pathways in the progression of FSGS: the endothelin-1 and angiotensin II systems. By simultaneously blocking these pathways, sparsentan aims to provide kidney-protective benefits beyond those achieved with current standard-of-care treatments.
FSGS affects approximately 40,000 patients in the United States and is a leading cause of end-stage kidney disease. The condition is characterized by progressive scarring of the glomeruli, resulting in protein leakage into the urine (proteinuria), kidney function decline, and eventually kidney failure in many patients.
"FSGS represents a significant unmet medical need with limited treatment options currently available," said Eric Dube, Ph.D., President and CEO of Travere Therapeutics. "The FDA's acceptance of our sNDA brings us one step closer to potentially providing a new therapeutic option for patients living with this challenging condition."
Clinical Evidence Supporting the Application
The sNDA submission is supported by data from the Phase 3 DUPLEX Study, which evaluated the efficacy and safety of sparsentan in patients with FSGS. The study met its primary endpoint, demonstrating a significant reduction in proteinuria compared to the active control, irbesartan, an angiotensin II receptor blocker (ARB) that represents current standard of care.
Key findings from the DUPLEX Study include:
- A 57% reduction in proteinuria from baseline at week 36 in the sparsentan group, compared to a 19% reduction in the irbesartan group
- Sustained proteinuria reduction through 108 weeks of treatment
- A favorable safety profile consistent with previous studies
Dr. Jonathan Barratt, Professor of Renal Medicine at the University of Leicester and a principal investigator in the DUPLEX Study, commented: "The sustained reduction in proteinuria observed with sparsentan is particularly encouraging, as proteinuria reduction is associated with improved long-term kidney outcomes in FSGS patients."
Regulatory Pathway and Implications
The FDA's decision to hold an advisory committee meeting suggests the agency recognizes both the importance of this potential therapy and the need for thorough evaluation of its benefit-risk profile. Advisory committees typically review complex applications and provide recommendations, though the FDA is not bound by these recommendations in its final decision.
If approved, sparsentan would become an important addition to the limited arsenal of treatments for FSGS. Current treatment approaches primarily rely on angiotensin-converting enzyme (ACE) inhibitors, ARBs, and immunosuppressive agents, which often provide inadequate disease control and can be associated with significant side effects.
Broader Context in Kidney Disease Treatment
Sparsentan's development represents part of a broader trend toward more targeted therapies for rare kidney diseases. The drug is also being evaluated for IgA nephropathy, another rare kidney condition, for which it received accelerated approval from the FDA in February 2023.
"The development of novel therapies like sparsentan reflects the growing understanding of the molecular mechanisms underlying rare kidney diseases," noted Dr. Katherine Tuttle, Executive Director for Research at Providence Health Care in Spokane, Washington. "This targeted approach holds promise for improving outcomes in conditions that have historically been difficult to treat effectively."
Looking Forward
As the January 2026 PDUFA date approaches, the nephrology community will be watching closely for additional data and the outcome of the FDA advisory committee meeting. For patients with FSGS, who currently face limited treatment options and a high risk of progression to kidney failure, the potential approval of sparsentan represents a significant development in addressing this challenging condition.
Travere Therapeutics has indicated that preparations are underway to support a potential commercial launch if approval is granted, including educational initiatives for healthcare providers and patient support programs.
