In this episode of the Rare Kidney Disease Show, a panel of nephrology experts explore the latest data on sparsentan, as presented at ASN Kidney Week 2024.

Dr. Hiddo Heerspink presents a post hoc analysis of the PROTECT trial comprised of patients who achieved complete proteinuria remission.

Dr. Chee Kay Cheung shares interim data from the SPARTAN study on sparsentan therapy in treatment-naïve patients with IgA nephropathy.

Lastly, Dr. Bruce Hendry discusses combination treatment of sparsentan with SGLT2i in the SPARTACUS study.

These discussions are introduced by Dr. Edgar Lerma, who offers his insights into the possible clinical implications of these data.

Luis Velez, MD is a board-certified community nephrologist in San Antonio, TX with expertise in hypertension and glomerular disorders.

Jessica Coleman, MD is a board-certified community nephrologist practicing between Savanah, GA and Charleston, SC with expertise in hypertension and glomerular disorders.

In this episode, Drs Velez and Coleman discuss management of IgAN patients from the viewpoint of community nephrologists. They discuss the evolution in their management of IgAN, highlighting the availability of new data such as RaDaR as a key driver of change. With greater awareness of the role of proteinuria, they advocate for early and aggressive treatment to avoid long term complications of IgAN.

Key Quotes:

• “RaDaR taught me that the traditional way of looking at IgA nephropathy is wrong. We realized this is a disease state that absolutely can progress and can progress more rapidly than what we initially appreciated and certainly at a younger age in these patients. (02:25)
• “When we look at patients with proteinuria, even just 0.5 g/d, a third of patients under 40 are going to progress to end stage kidney disease in ten years [RaDaR].” (04:30)
• “With the RaDaR data, we see levels of proteinuria 0.5 -0.8 g/d still being significant markers for disease progression.” (08:56)

Key Takeaways:

• IgAN is not a benign disease
• Proteinuria is the most important prognostic indicator of disease progression in IgA Nephropathy
• HCPs should be targeting lower proteinuria goals to achieve complete remission <0.3 g/d
• The updated KDIGO Guidelines should support clinicians’ decisions to target complete remission

Episode Overview:

Donald Kohan, PhD is an Emeritus Professor at the University of Utah Health with expertise in endothelin receptors, sodium transporters, and the renin-angiotensin-aldosterone system in chronic kidney disease.

In this episode, Professor Kohan provides an overview of the endothelin system and how it relates to the pathophysiology of chronic kidney disease and IgA nephropathy specifically.

Key Quotes:

• “Endothelin 1 is a really unusual molecule. It's highly stable because it has 2 interchain disulfide bonds that resist degradation. It's extremely potent having about 10 fold higher potency than any other known vasoactive factor.”
• “Angiotensin and ET-1 cause their effects through different pathways.”
• “Angiotensin stimulates transient calcium release, which causes more short-term contraction and other effects. While endothelin 1 stimulates more sustained calcium release, which then elicits longer lasting pathophysiologic effects.”

Key Takeaways:

• (04:41) Endothelin-1 acts via ETA receptors to cause vasoconstriction, fibrosis, cell proliferation and other effects that promote chronic kidney disease
• (06:15) The endothelin and renin-angiotensin systems interact, forming a vicious cycle that worsens kidney injury
• (12:19) In IgA nephropathy models, combined ETA + angiotensin receptor blockade with sparsentan reduced proteinuria and kidney injury more than angiotensin blockade alone