Following two late-stage failures, Travere Therapeutics has unveiled the results of two Phase III studies, attempting to regain Filspari’s footing in IgA nephropathy and focal segmental glomerulosclerosis.
Pictured: Artistic illustration of the kidneys, showing the internal network of tubes/iStock, peterschreiber.media
Travere Therapeutics on Friday released more data from the Phase III PROTECT and DUPLEX studies—in IgA nephropathy and focal segmental glomerulosclerosis, respectively—showing that treatment with Filspari (sparsentan) can preserve kidney function in these diseases.
The results were presented at the American Society of Nephrology’s Kidney Week 2023. Travere also published PROTECT data in The Lancet and DUPLEX data in The New England Journal of Medicine.
PROTECT is a randomized, double-blinded, parallel-arm and active-controlled trial of 404 IgA nephropathy (IgAN) patients who were treated with either 400-mg Filspari or 300-mg irbersartan. In February 2023, interim data from PROTECT showing that Filspari, an oral, dual endothelin angiotensin receptor antagonist, strongly reduced proteinuria after 36 weeks of treatment became the FDA’s basis for granting the drug accelerated approval for IgAN.
For full approval, however, Travere was relying on estimated glomerular filtration rate (eGFR), a key secondary endpoint in PROTECT that measures kidney function. In September 2023, the company reported that Filspari narrowly missed its eGFR mark.
In Friday’s data drop, Travere reported that Filspari resulted in “one of the slowest rates of kidney function decline in an IgAN trial of its kind.” Treated patients saw a 2.7- and 2.9-mL/min/1.73 m2 annual decline in chronic and total eGFR slope, respectively.
Decline in kidney function was also slower with Filspari versus irbesartan, such that at two years patients treated with Travere’s drug had 3.7-mL/min/1.73m2 higher eGFR.
These data indicate that Filspari “has an important place in the IgAN treatment landscape as a long-term foundational therapy,” Brad Rovin, medical director at the Ohio State University Center for Clinical Research Management and steering committee member for PROTECT, said in a statement.
Besides IgAN, Travere is also developing sparsentan for the rare kidney disease focal segmental glomerulosclerosis (FSGS), for which it is running the DUPLEX trial, a randomized, double-blinded and active-controlled trial with more than 370 patients enrolled. In May 2023, Travere reported that sparsentan failed its primary efficacy endpoint, yielding no significant improvement in eGFR versus irbesartan.
However, two-year follow-up data presented on Friday demonstrated “clinically meaningful and durable” improvements in proteinuria following sparsentan treatment. Patients given sparsentan saw a 50% drop in proteinuria from baseline, while irbesartan counterparts only achieved a 32% reduction. Sparsentan also resulted in a higher rate of complete remission of proteinuria.
Tristan Manalac is an independent science writer based in Metro Manila, Philippines. He can be reached at tristan@tristanmanalac.com or tristan.manalac@biospace.com.
