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# FDA Extends Review for Filspari in Kidney Disease
- URL: https://www.fdaweb.com/fda-extends-review-for-filspari-in-kidney-disease/
- Published: 2026-01-13T12:00:00.000Z
- Updated: 2026-09-14T15:30:33.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5160483

FDA has extended by three months its review of a Travere Therapeutics supplemental NDA for Filspari in focal segmental glomerulosclerosis (FSGS), pushing the user fee review target action date to 4/13.

The extension was prompted after the agency determined that recently submitted responses from Travere to FDA information requests constituted a major amendment to the application. The additional materials were requested to further characterize the clinical benefit of Filspari in FSGS. Travere said FDA did not request any new information related to the drug’s safety profile or manufacturing.

Filspari is a non-immunosuppressive, oral therapy that targets kidney podocyte injury by blocking both the endothelin A receptor and angiotensin II subtype 1 receptor. It is currently approved to slow kidney function decline in patients with immunoglobulin A nephropathy.

The company said the submission is backed by data from the Phase 3 DUPLEX and Phase 2 DUET studies, which demonstrated that Filspari achieved significant and sustained reductions in proteinuria — a key marker of kidney disease progression — compared to standard therapy irbesartan. Although the DUPLEX study did not meet its primary endpoint related to kidney function decline over 108 weeks, it did show significant clinical benefits, including a lower rate of progression to end-stage kidney disease, it said.