FDA Grants Accelerated Approval to Filspari for Rare Kidney Disease

The FDA has granted accelerated approval to Travere Therapeutics’ Filspari (sparsentan) to reduce proteinuria, protein in the urine, in adults with primary IgAN. IgA nephropathy (IgAN), also called Berger's disease, is a rare progressive kidney disease characterized by the buildup of immunoglobulin A, a protein that helps the body fight infections, in the kidneys. The deposits of IgA cause a breakdown of the normal filtering mechanisms in the kidney, leading to blood in the urine (hematuria), protein in the urine, and a progressive loss of kidney function. It effects up to 150,000 people in the United States.

Filspari is a first-in-class, once-daily, oral medication designed to selectively target two critical pathways in the disease progression of IgAN (endothelin-1 and angiotensin II).

Filpari is expected to be available beginning the week of Feb. 27, 2023. Travere is offering Filspari at a wholesale acquisition cost of $9,900 for a 30-day supply. Travere will be providing a comprehensive patient support program with $0 copay for qualified patients.

Because of the risk of liver abnormalities associated with Filpari, it will be administrated through a Risk Evaluation and Mitigation Strategies program. Liver monitoring will be required monthly for the first year of treatment and then every three months. Additionally, monthly pregnancy monitoring will be required of all because of the risk to the embryo.

The approval is based on clinically meaningful and statistically significant improvements in proteinuria in the pivotal and ongoing phase 3 PROTECT study. The PROTECT study is a clinical trial evaluating the safety and efficacy of 400 mg of Filspari compared with 300 mg of irbesartan, in 404 patients ages 18 years and up. Positive top-line interim results showed that after 36 weeks of treatment, patients receiving Filspari achieved a mean reduction in proteinuria from baseline of 49.8%, compared to a mean reduction in proteinuria from baseline of 15.1% for irbesartan-treated patients.

Brad Rovin, M.D.

“A high proportion of individuals diagnosed with this disease do not sufficiently respond to the historical standard treatment, which has been therapies that are not indicated for IgA nephropathy. As a result, many patients have struggled to manage their disease and have progressed more quickly to kidney failure,” Brad Rovin, M.D., medical director at Ohio State University Center for Clinical Research Management, director of the Division for Nephrology, and steering committee member for the PROTECT clinical trial, said in a press release.

Per request from the FDA, the efficacy data contained in the FDA-approved label is a post-hoc sensitivity analysis that evaluates the first 281 randomized patients, a subset of the full trial population. The mean reduction in proteinuria from baseline in the post-hoc sensitivity analysis is 45% for Filspari versus 15% for irbesartan. The study continues, and results from the confirmatory endpoint analysis are expected in the fourth quarter of 2023.

Most common adverse events are peripheral edema, hypotension, dizziness, hyperkalemia, and anemia.