With the regulator’s traditional green light in IgA nephropathy, Filspari is up against Novartis’ Fabhalta—which won accelerated approval last month—and Calliditas’ Tarpeyo, which was approved in December 2023.
The FDA on Thursday granted traditional approval to Travere Therapeutics’ Filspari (sparsentan) for the treatment of patients with primary IgA nephropathy.
Filspari’s full approval expands its indication, allowing use of the small molecule blocker to slow the decline of kidney function in adult patients who are at risk of disease progression—while also removing a previous requirement of having a specific urinary protein level. According to Travere, Filspari is the only oral, once-daily and non-immunosuppressive treatment for IgA nephropathy (IgAN), specifically targeting glomerular injury in the kidney.
“Full approval now enables physicians to confidently prescribe Filspari more broadly as a once-daily, oral, non-immunosuppressive treatment, that can provide superior preservation of kidney function and replace current standard of care,” Travere CEO Eric Dube said in a statement. “Filspari is well positioned to become foundational care for IgAN as the treatment landscape evolves.”
Jefferies analyst Maury Raycroft in a note to investors said Filspari’s full approval was timed well with the new Aug. 30 draft guidance from the global nonprofit Kidney Disease Improving Global Outcomes (KDIGO). The recommendations lowered the urine protein-creatinine ratio (UPCR) threshold for at-risk patients while also raising treatment goals.
Filspari is one of the few agents that can satisfy the new KDIGO guidelines, according to Raycroft, who contends that Travere’s drug can address the immune and inflammatory drivers of IgAN while also targeting generic drivers of chronic kidney disease.
Designed to be taken orally, Filspari is a small molecule blocker of the endothelin and angiotensin II receptors, both of which are thought to play a role in the pathogenesis of IgAN, according to its label. Filspari comes with a boxed warning for hepatotoxicity and embryo-fetal toxicity and is available only through a risk evaluation and mitigation strategies program.
The FDA granted Filspari accelerated approval in February 2023 using proteinuria data from the Phase III PROTECT study. At the time, Travere had successfully shown that Filspari could lower urine protein levels more than three times as much as Avapro (irbesartan), the active control.
Travere kept PROTECT to serve as Filspari’s confirmatory trial, but in September 2023 the biotech announced that the trial had “narrowly” missed its efficacy endpoint of the total slope of estimated glomerular filtration rate (eGFR). Nevertheless, Dube continued to express confidence in Filspari and highlighted its effects on proteinuria and eGFR decline.
In Thursday’s announcement, Travere again touted Filspari’s clinical benefit, noting that the drug could significantly slow decline in kidney function. At week 110, patients on Filspari showed mean eGFR slope of –3.0 mL/min/1.73m2/year, as opposed to –4.2 mL/min/1.73m2/year in patients treated with Avapro. The treatment effect was statistically significant in favor of Filpsari, with a p-value of 0.0168.
In addition, long-term follow-up data from PROTECT showed that the 36-week benefit of Filpsari on proteinuria was durable through 110 weeks.
Travere competes with Calliditas Therapeutics and pharma giant Novartis in the IgAN space. In December 2023, Calliditas secured full approval for Tarpeyo (budesonide), while Novartis won accelerated approval for Fabhalta (iptacopan) last month.
