Travere Therapeutics has received the US Food and Drug Administration (FDA) full approval for Filspari (sparsentan) to reduce proteinuria in adult and paediatric patients aged eight years and above with focal segmental glomerulosclerosis (FSGS) without nephrotic syndrome.

The approval makes Filspari the first and only FDA-approved medicine to treat FSGS, expanding its use beyond IgA nephropathy (IgAN) into a second rare kidney condition.

FSGS is a rare disease, and patients without nephrotic syndrome include a group consistent with kidney disease: improving global outcomes (KDIGO) guidelines for glomerular diseases.

Nephrotic syndrome typically features proteinuria higher than 3.5g per 24 hours, oedema, and albumin lower than 3.0g/dL.

In the Phase III DUPLEX study, said to be the largest comparative trial in FSGS, Filspari showed a 46% reduction in proteinuria for the entire study population from baseline to week 108 while irbesartan showed a 30% reduction.

In those without nephrotic syndrome, Filspari resulted in a 48% reduction, compared to 27% for irbesartan. Patients on the therapy also demonstrated a 1.1ml/min/1.73m² mean difference in estimated glomerular filtration rate (eGFR) change versus irbesartan.

Travere Therapeutics president and CEO Eric Dube said: “This approval reflects years of perseverance and our belief that those living with FSGS deserve better. It also builds on our leadership and progress in rare kidney diseases, expanding Filspari’s potential reach to more than 100,000 people in the US with FSGS and IgAN who need better treatment options.

“Filspari will be available for nephrologists to immediately prescribe to individuals with FSGS. We are profoundly grateful to the patients, caregivers, investigators, healthcare providers, regulators and advocates who made this moment possible.”

In February 2025, Travere planned to seek FDA approval for Filspari, despite not achieving the primary endpoint in its pivotal trial.