Travere Snags Accelerated Approval for First Non-Immunosuppressive IgAN Therapy

After over a decade of development, Travere Therapeutics, formerly known as Retrophin, announced that the FDA approved its non-immunosuppressive IgAN therapy, Filspari, as the first of its kind under the accelerated approval program. Under its current approval status, the FDA recognized that the drug decreases proteinuria (protein in the urine), but the company plans to submit data at the end of the year demonstrating the drug’s ability to slow kidney disease.

A Step Forward in IgAN Treatment

Immunoglobulin A Nephropathy (IgAN) is a rare progressive kidney disease caused by a buildup of Immunoglobulin A (IgA), which helps the body fight infections in the kidney. The excessive IgA deposits break down filtering mechanisms and can result in blood and protein in the urine, which can ultimately lead to kidney failure. 

Most current treatments consist of repurposed drugs like angiotensin-receptor blockers and angiotensin-converting enzyme inhibitors commonly used to treat high blood pressure. Travere’s Filspari differs from these repurposed drugs because it targets angiotensin and endothelin, two critical pathways in IgAN’s disease progression. 

One of the only other drugs approved specifically for IgAN is Calliditas Therapeutics’ Tarpeyo, a corticosteroid approved in 2021. Travere CEO Eric Dube explained that many doctors are reluctant to prescribe corticosteroids for IgAN because of the potential side effects, including hypercortisolism (high levels of the cortisol hormone) and adrenal suppression (unable to produce enough cortisol). Patients with moderate to severe liver impairment are more likely to experience these side effects. 

Both Tarpeyo and Filspari gained accelerated approval for reducing proteinuria. Filspari might gain an advantage over Tarpeyo, for the time being, because it is not an immunosuppressant, which may open the door to a wider pool of IgAN patients. 

Of the 150,000 Americans with IgAN, Travere estimates that 30-50,000 patients could benefit from Filspari under its accelerated approval status. The company expects Filspari to hit the market by next week with a new patient support program to assist eligible patients in receiving the once-daily oral pill. 

Related Article: Vera Therapeutics Eyes Phase 3 For Kidney Disease Candidate Following Positive Data

Filspari’s Clinical Results and Confirmatory Future

Travere posted topline results from its Phase 3 PROTECT study in August 2021, where Filspari demonstrated a mean reduction in proteinuria of 49.8% compared to 15.1% in the control group. The reduction in proteinuria acted as the surrogate endpoint for the drug’s accelerated approval, but the company is continuing the PROTECT study to confirm primary endpoints to gain traditional approval. 

By the end of 2023, Travere hopes to release a confirmatory endpoint analysis to support traditional approval for Filspari. 

With the accelerated approval, though, Travere’s partner, Ligand Pharmaceuticals Incorporated, stands to gain $15.3 million from a licensing deal the two struck in 2012. Ligand could receive additional milestone payments and 9% royalties on net sales from Filspari. 

With promising data backing Filspari’s accelerated approval, Travere appears set on pushing the drug to traditional approval with primary endpoint data. The company plans to publish that data by the end of the year, and 2024 could see the first traditionally approved non-immunosuppressive IgAN therapy on the market. 

Author

Reed Slater