FDA Grants Full Approval to Travere’s Filspari for FSGS

Rare Daily Staff

The U.S. Food and Drug Administration has granted Travere Therapeutics full approval for Filspari, the first and only FDA-authorized medicine for the rare kidney condition focal segmental glomerulosclerosis (FSGS).

The approval broadens the use of Filspari beyond IgA nephropathy into a second rare kidney disease, establishing a new treatment option for thousands of patients who have long relied on off-label therapies such as chronic steroid use.

The FDA approved Filspari to reduce proteinuria in adult and pediatric patients aged 8 years and older with FSGS who do not have nephrotic syndrome. Travere estimates that more than 30,000 people in the United States have FSGS without nephrotic syndrome. The expanded indication brings Filspari’s total eligible population across FSGS and IgA nephropathy to more than 100,000 patients. Filspari is already the most commonly prescribed FDA-approved medicine for IgA nephropathy, where it is indicated to slow the decline in kidney function in adults at risk for disease progression.

The approval in FSGS is supported by data from the phase 3 DUPLEX study—the largest interventional trial conducted in the disease—which enrolled 371 patients ages 8 to 75 with biopsy-proven or genetic FSGS. In the overall study population, patients treated with Filspari achieved a 46 percent reduction in proteinuria from baseline to week 108, compared with a 30 percent reduction among those receiving the maximum labeled dose of irbesartan.

In patients without nephrotic syndrome, Filspari’s effect was more pronounced, with a 48 percent reduction in proteinuria versus 27 percent with irbesartan. Across adult and pediatric subgroups, the safety profile was generally comparable to irbesartan and consistent with prior Filspari studies.

FSGS without nephrotic syndrome is thought to result largely from stress on the kidney’s glomeruli and activation of inflammatory and fibrotic pathways. Filspari is an oral, dual endothelin A and angiotensin II receptor antagonist designed to address these processes by dampening vasoconstrictive, inflammatory, and profibrotic signaling to help protect the kidneys and reduce damage.

The drug carries a boxed warning for hepatotoxicity and embryo-fetal toxicity and is available only through the Filspari Risk Evaluation and Mitigation Strategy (REMS) program. Transaminases and bilirubin must be checked before initiating therapy and every three months during treatment. Filspari is contraindicated in pregnancy and should not be coadministered with angiotensin receptor blockers, endothelin receptor antagonists, or aliskiren. Common adverse reactions in FSGS include peripheral edema, hypotension, hyperkalemia, dizziness, and anemia.

“Today marks a historic milestone for people living with FSGS, who for the first time have an FDA-approved medicine for this rare and devastating condition,” said Eric Dube, president and CEO of Travere Therapeutics.