FDA approves Travere's sparsentan as first drug for rare kidney scarring disease

The U.S. Food and Drug Administration has approved sparsentan as the first drug to treat focal segmental glomerulosclerosis, a rare kidney disease, according to Travere Therapeutics.

FSGS is a kidney disease where the filtering units become scarred. This can cause swelling, loss of protein in urine, and eventually kidney failure. Reuters reports that over 40,000 people in the U.S. have FSGS, with similar numbers in Europe.

The drug works by targeting two specific receptors to reduce the amount of protein lost through the kidneys. According to the company, this helps slow the progression of the disease. Travere said kidney specialists can start prescribing it to FSGS patients immediately.

The FDA approval expands the existing authorization for sparsentan, which is already sold under the brand name Filspari. Regulators first cleared Filspari in 2023 for IgA nephropathy, another progressive autoimmune kidney disorder, though the drug's label includes boxed warnings flagging risks of liver injury and fetal harm.

Before granting the FSGS indication, the FDA had in January pushed back its review timeline, requesting more evidence of the drug's clinical benefit. For the IgA nephropathy indication, Filspari has a list price of roughly $9,900 per month, or about $170,000 annually, according to Reuters. Because FSGS requires a higher dose, Jefferies analyst Maury Raycroft told Reuters that the drug's price for that condition could be about double the IgAN price.

Filspari brought in $103.3 million in sales during the last three months of the year. Travere licensed the drug from Ligand Pharmaceuticals in 2012. According to Reuters, Ligand receives 9% of global revenue and milestone payments under the agreement.

Atrasentan, a competing treatment from Novartis in Switzerland, is now in a mid-stage clinical trial for the same group of patients, Reuters reports.