FDA
FDA OK's Filspari for focal segmental glomerulosclerosis
On April 13, 2026, FDA approved Filspari (sparsentan) to reduce proteinuria in adult and pediatric patients aged 8 years and older with focal segmental glomerulosclerosis (FSGS) without nephrotic syndrome. Filspari is the first FDA‑approved drug for FSGS, a proteinuric kidney disease affecting children and adults, characterized by progressive glomerular scarring, clinically significant proteinuria that contributes to ongoing renal injury, and a high risk of progression to kidney failure.
“For decades, treatment options have been limited, often relying on off-label therapies such as long-term steroids that can carry a significant burden for patients,” said Kirk Campbell, MD, president of the National Kidney Foundation and chief of the Division of Renal-Electrolyte and Hypertension at University of Pennsylvania. "Filspari provides nephrologists with a new FDA-approved option for patients living with FSGS.”
Efficacy
Approval was based on the phase 3 DUPLEX trial, a randomized, active‑controlled study comparing Filspari with maximum labeled‑dose irbesartan in pediatric and adult patients with biopsy-proven or genetic FSGS.
In the overall study population, treatment with Filspari resulted in a 46% reduction in proteinuria from baseline to week 108, compared with a 30% reduction in patients treated with irbesartan (nominal p=0.0299).
Among patients without nephrotic syndrome, Filspari demonstrated greater benefits across both proteinuria and kidney function outcomes. In this subgroup, treatment with Filspari resulted in a 48% reduction in proteinuria vs. 27% with irbesartan at week 108 (nominal p=0.0075). Patients without nephrotic syndrome treated with Filspari also showed a treatment benefit in eGFR, with a mean difference of 1.1 mL/min/1.73 m² based on change from baseline to week 108 (–11.3 mL/min/1.73 m² with Filspari vs. –12.4 mL/min/1.73 m² with irbesartan).
Safety
In FSGS patients treated with Filspari, the most common adverse reactions (≥5%) were peripheral edema, hypotension (including orthostatic hypotension), hyperkalemia, dizziness, and anemia.
The prescribing information for Filspari carries boxed warnings for hepatotoxicity and embryo‑fetal toxicity and the drug is available only through a restricted distribution program- Filspari Risk Evaluation and Mitigation Strategy (REMS). Additional warnings and precautions applicable across all indications include hypotension, acute kidney injury, hyperkalemia, and fluid retention. Concomitant use with ARBs, endothelin receptor antagonists, or aliskiren is contraindicated.
Sources:
Travere Therapeutics, Inc. (2026, April 13). Travere Therapeutics Announces Full FDA Approval of Filspari® (sparsentan), the First and Only Approved Medicine for FSGS.
Filspari (sparsentan). [Package insert]. Travere Therapeutics, Inc. https://travere.com/wp-content/uploads/2026/04/filspari-uspi-med-guide-20260413-approved.pdf Dated April 2026.