FDA Extends Sparsentan (Filspari) sNDA Review for Focal Segmental Glomerulosclerosis

The US Food and Drug Administration (FDA) announced the extension of the review timeline for the supplemental New Drug Application (sNDA) of sparsentan (Filspari) for focal segmental glomerulosclerosis (FSGS).1

In a press release, Travere Therapeutics, Inc. announced the FDA has moved the Prescription Drug User Fee Act (PDUFA) target action date, which was expected on January 13, 2026, to April 13, 2026. Otherwise, no additional information relating to the safety or manufacturing of the drug has been requested.1

“We believe in the potential of [sparsentan] to make a meaningful difference in the lives of people living with FSGS and are encouraged by the productive engagement with the FDA,” said Eric Dube, PhD, the president and chief executive officer of Travere Therapeutics, in a company statement. “We remain focused on the goal of bringing [sparsentan] to the patients who urgently need an effective medicine for this devastating and rapidly progressing disease and remain committed to working with the Agency during the extension period. In parallel, our commercial preparations continue to ensure a successful launch, if approved.”1

The announcement comes after the FDA had requested further characterization of the clinical benefit of sparsentan. Upon submission of responses, the FDA determined they constituted a Major Amendment to the sNDA, and extended the PDUFA action date accordingly.1

Sparsentan is the only non-immunosuppressive, oral medication designed to directly target podocyte injury by optimally blocking the endothelin A receptor and the angiotensin II subtype 1 receptor.1,2

The Agency previously approved sparsentan for slowing kidney function decline in adults with IgA nephropathy (IgAN) in September 2024, based on 2-year confirmatory results from the phase 3 PROTECT study. In May 2025, the therapeutic’s sNDA was accepted by the FDA for the treatment of adults with FSGS. Additionally, the FDA removed the Advisory Committee Meeting for the therapeutic’s sNDA in September 2025, after the Agency had initially said it would require one.1,2

The sNDA for the use of sparsentan in FSGS was supported by findings from the phase 3 DUPLEX Study and the phase 2 DUET Study.

The phase 3 DUPEX study was the largest interventional study in FSGS, as well as the only one against a maximally dosed active comparator. While DUPLEX achieved its pre-specified interim FSGS partial remission of proteinuria endpoint with statistical significance at 36 weeks, it did not achieve the primary efficacy eGFR slope endpoint over 108 weeks of treatment. The 2-year results from the study were published in the New England Journal of Medicine and showed that sparsentan delivered clinically meaningful benefit at 108 weeks with significant proteinuria reduction, higher rates of partial and complete remission, and a lower rate of end-stage kidney disease compared to the active control.

In concurrence, the phase 2 DUET study met the primary efficacy endpoint for the combined treatment group, demonstrating a > 2-fold reduction in proteinuria compared to irbesartan. Its safety profile was consistent across all clinical trials and comparable to the maximally dosed active control.1,2

If approved, sparsentan would be the first medication indicated for the treatment of adults with FSGS.1,2

References

1. Travere Therapeutics Announces FDA Extends Review of sNDA for FILSPARI® (sparsentan) in FSGS. Travere.com. Published 2025. Accessed January 13, 2026. https://ir.travere.com/press-releases/news-details/2026/Travere-Therapeutics-Announces-FDA-Extends-Review-of-sNDA-for-FILSPARI-sparsentan-in-FSGS/default.aspx

2. Travere Therapeutics Announces FDA Acceptance of sNDA for FILSPARI® (sparsentan) in FSGS. Travere.com. Published 2025. Accessed January 5, 2026. https://ir.travere.com/press-releases/news-details/2025/Travere-Therapeutics-Announces-FDA-Acceptance-of-sNDA-for-FILSPARI-sparsentan-in-FSGS/default.aspx