Yes, Filspari Treats Kidney Disease
Filspari (sparsentan) is FDA-approved for adults with primary immunoglobulin A nephropathy (IgAN), a rare kidney disease causing progressive loss of kidney function due to IgA buildup in the glomeruli.[1] It reduces proteinuria, a key marker of kidney damage, and slows disease progression.
How Filspari Works in IgAN
Filspari is a dual endothelin and angiotensin II receptor antagonist. It blocks receptors that promote inflammation and fibrosis in the kidneys, lowering blood pressure in glomerular capillaries and protecting filtration units.[1][2] In the PROTECT trial, it reduced proteinuria by 45.6% at 36 weeks versus 15.1% with irbesartan, with sustained eGFR slope benefits.[3]
When Was It Approved and for What Stages?
Approved by the FDA in February 2023 under accelerated approval for IgAN adults at risk of rapid progression, based on proteinuria reduction.[1] Full approval requires confirmatory trials like PROTECT, ongoing through 2026. Not approved for other kidney diseases like diabetic nephropathy or FSGS.
Common Side Effects Patients Report
Hepatotoxicity (monitor ALT/AST monthly), edema, hypotension, anemia, and hyperkalemia occur in >10% of users.[1] Risk of embryo-fetal toxicity requires contraception and REMS program enrollment.
How Does It Compare to Other IgAN Treatments?
Outperforms irbesartan (ARB) in proteinuria reduction; SGLT2 inhibitors like Farxiga also approved for IgAN but target different pathways.[3] Unlike steroids (e.g., Nefecon), Filspari is steroid-free, appealing for long-term use.
Who Makes Filspari and What's the Patent Outlook?
Travere Therapeutics markets it. Key U.S. patents expire in the 2030s; no major challenges listed yet.[4] Priced at ~$15,000/month before discounts.
[1]: FDA Label for Filspari
[2]: Travere Therapeutics - Filspari Mechanism
[3]: New England Journal of Medicine - PROTECT Trial
[4]: DrugPatentWatch.com - Sparsentan Patents