Shares of Travere Therapeutics (NASDAQ:TVTX) surged 44% on Tuesday after the U.S. Food and Drug Administration granted approval for FILSPARI in the treatment of focal segmental glomerulosclerosis (FSGS), a rare kidney disorder.
The approval specifies FILSPARI for reducing proteinuria in adult and pediatric patients aged 8 years and older with FSGS who do not meet criteria for nephrotic syndrome. With this decision, FILSPARI becomes the first and only FDA-approved therapy for FSGS, marking an expansion of its approved indications beyond IgA nephropathy into a second rare renal disease.
Travere estimates that the addressable U.S. population for FILSPARI exceeds 30,000 individuals with FSGS who do not have nephrotic syndrome. The regulatory definition of nephrotic syndrome applied in the approval requires the simultaneous presence of three clinical criteria: proteinuria greater than 3.5 g/24 hours, edema, and serum albumin under 3.0 g/dL.
Clinical data behind the approval
The FDA decision was supported by results from the Phase 3 DUPLEX Study. Across the trial population, patients receiving FILSPARI had a statistically significant 46% reduction in proteinuria from baseline to Week 108, compared with a 30% reduction observed in patients treated with the maximum labeled dose of irbesartan.
Among the subgroup of patients without nephrotic syndrome, FILSPARI produced a 48% reduction in proteinuria from baseline to Week 108, versus a 27% reduction for those on irbesartan. In addition to improvements in proteinuria, FILSPARI-treated patients without nephrotic syndrome demonstrated a benefit in estimated glomerular filtration rate (eGFR), with a treatment difference of 1.1 mL/min/1.73 m2 based on mean change from baseline to Week 108.
The drug was reported to be generally well tolerated in both adult and pediatric cohorts, with an overall safety profile described as comparable to that of irbesartan.
Market and analyst response
Following the approval, Guggenheim analyst Vamil Divan raised his price target on Travere to $54.00 from $49.00 while keeping a Buy rating. Divan commented: "Overall, we believe the final label is better than we expected, with the approved population broader than our prior working assumption in that it spans both primary and secondary FSGS rather than being limited to the primary/genetic population that we believe was the management’s and Street’s base case expectation."
What this means for stakeholders
For patients and clinicians managing FSGS, the approval provides a new, approved therapeutic option specifically indicated to reduce proteinuria in those aged 8 and older without nephrotic syndrome. For Travere, the expanded label establishes FILSPARI as a treatment across two rare kidney diseases, potentially enlarging the commercial opportunity within a defined U.S. population estimated by the company to be over 30,000 patients.
Investors reacted strongly in the short term, as reflected in the 44% share price increase on the trading day of the announcement.