Travere Therapeutics and CSL Vifor are nearing EU approval for sparsentan in IgA nephropathy (IgAN) after receiving a positive opinion from the European Medicines Agency's (EMA) human medicines committee (CHMP). The CHMP recommends sparsentan for adults with primary IgAN who have a urine protein excretion above 1 g/day or a urine protein-to-creatinine ratio of 0.75 g/g or more.
This decision positions Travere and CSL to potentially introduce a first-in-class treatment for IgAN, a rare kidney disorder and a leading cause of kidney failure. IgAN, also known as Berger's disease, affects approximately 115,000 people in the EU, with an estimated prevalence of 2.5 cases per 10,000 individuals. The autoimmune disease is characterized by the accumulation of antibodies in the kidneys, leading to inflammation and scarring.
Mechanism of Action and Clinical Data
Sparsentan is an oral antagonist of both endothelin type A (ETA) and angiotensin II subtype 1 (AT1) receptors, both implicated in the progression of kidney disease. In the US, sparsentan has already received accelerated approval as Filspari. The FDA's approval was based on data from the pivotal PROTECT study, which demonstrated a reduction in protein levels in the urine of IgAN patients, a surrogate marker for kidney function. However, the drug did not significantly improve the estimated glomerular filtration rate (eGFR), considered a more direct measure of kidney function.
Travere remains optimistic that the totality of the data will support full approval and intends to submit the data to the FDA. The company emphasizes that PROTECT is the only head-to-head study in IgAN comparing sparsentan to a maximally labeled dose of irbesartan, an angiotensin 2 receptor antagonist and a current standard of care.
Market Landscape and Competition
Travere launched Filspari at a price lower than Calliditas' Tarpeyo (budesonide), a corticosteroid-based therapy that was the first FDA-approved treatment for IgAN in 2021, achieving $104 million in sales in 2023. Travere reported $15 million in Filspari sales in the fourth quarter and $29 million since its launch in February.
Both Filspari and Tarpeyo may face competition from Novartis' iptacopan, a targeted factor B inhibitor that demonstrated efficacy in reducing proteinuria in an interim analysis of the phase 3 APPLAUSE-IgAN trial. Final results from the APPLAUSE-IgAN study are expected next year, and Novartis is in discussions with the FDA regarding a potential early filing based on the current data. Analysts at Jefferies have projected that iptacopan could reach $3.6 billion in peak annual sales if approved for all its target indications, including IgAN, paroxysmal nocturnal haemoglobinuria (PNH), atypical haemolytic uraemic syndrome (aHUS), C3 glomerulopathy (C3G), and idiopathic membranous nephropathy (IMN).
