With the path to a blockbuster product in sight, Travele Therapeutics is ready to hit the ground running following Monday’s breakthrough approval of Filspari for focal segmental glomerulosclerosis (FSGS).
The company said in a post-approval presentation that Filspari is the first product approved for a rare kidney disease and is poised to reach more than 30,000 eligible FSGS patients. Building on Filspari’s experience in greenlighting IgA nephrography (IgAN) in 2023, Travelere boasts a “ready-to-execute” commercial platform that can support “long-term, sustainable revenue growth,” the company said.
Combined with the IgAN population already covered by the drug, Filspari now has the potential to reach more than 100,000 patients, Travere said.
From a market watcher’s perspective, Evercore ISI analysts expect peak sales from Filspari’s newly granted FSGS adaptation to be $1.4 billion, while sales related to the use of IgAN are expected to reach up to $800 million, the analysts wrote in a recent note to clients.
Travelere, meanwhile, is aiming even higher, estimating the potential peak sales opportunity for Filspari in the U.S. to exceed $3 billion.
To get there, the company outlined a detailed launch plan that includes a customized patient support program built around FSGS, a field team of more than 100 people focused on patient and physician education, and a payer access infrastructure based on PhilSpari’s IgAN positioning.
Once given the green light, Travele will immediately make Filspari available for new indications, which the company describes as a benefit of its “streamlined logistics.”
Filspari’s new label specifies its use to reduce proteinuria, or protein in the urine, in FSGS patients aged 8 years and older without nephrotic syndrome. The Evercore team noted that Filspari earned a broad label covering multiple disease subtypes, except that it “surprisingly” excluded patients with nephrotic syndrome, a kidney disease characterized by a specific range of high proteinuria levels.
Still, analysts noted that the lack of a nephrosis-specific label only affects about 15% of the real-world FSGS patient population. The defined label can be attributed to Filspari showing a greater reduction in proteinuria across a cohort of patients without nephrotic syndrome in Travele’s Duplex study, with a 39% reduction from baseline levels in these patients compared to the 22% seen in the overall study population, the company explained.
Travere is working quickly to ramp up due to the “high urgency” of treating FSGS. With more than 75% of FSGS patients expected to progress to dialysis, and around 75% of nephrologists surveyed saying the condition is “extremely difficult” to manage, the company aims to capitalize on “awareness and appetite” for the new product. In addition, there is significant crossover opportunity with 80% overlap in providers and prescribers offering Filspari for IgA nephrography, Dr. Travere noted.
In this lead indication, Filspari remains resolute against competition for IgAN from Novartis and holds the title of the “most commonly prescribed” drug for IgAN approved by the FDA to date, the company said. Filspari’s full-year sales in 2025 were $322 million, an increase of 144% compared to 2024.
In the short term, Evercore analysts expect sales from new indications for Filspari to increase from an expected $55 million in 2026 to $315 million in 2027 and an estimated $640 million in 2028.
Travelle overcame numerous hurdles on the road to FSGS approval for Filspari, which was delayed by three months as the FDA requested more information characterizing the drug’s clinical benefits.
The Phase 3 Duplex study failed to meet its primary endpoint in 2023, prompting the creation of a new endpoint for the FSGS clinical trial. More recently, concerns about the FDA’s handling of rare disease drug approvals have begun to emerge, raising concerns about how Filspari will fare fairly in the FDA window.
Now that Philspari’s consent is secured, Evercore analysts argued that the approval represents a “significant positive” for the overall flexibility of nephrology regulation, which is rare.
