Sparsentan for Proteinuria After Kidney Transplant

(SPARX Trial)

This trial tests the safety and effectiveness of sparsentan, a new medication, for individuals with proteinuria (excess protein in urine) following a kidney transplant. The goal is to determine if sparsentan can reduce protein levels and improve kidney function. This study targets those who had a kidney transplant over a year ago and have conditions like IgAN or FSGS, which are patterns of kidney disease. Participants should have stable blood pressure and no recent major infections or other serious medical conditions. As a Phase 4 trial, sparsentan has already received FDA approval and proven effective, and this research aims to understand how it benefits more patients.

The trial does not specify if you must stop taking your current medications, but it requires that any immunosuppressive therapy (IST) regimen be stable for more than 6 weeks before starting the trial. If you're on an ACEI, ARB, or SGLT2 inhibitor, your dose must also be stable for at least 6 weeks before screening.

Research has shown that sparsentan is generally well-tolerated. In a study comparing sparsentan to irbesartan, sparsentan significantly reduced protein in the urine, a positive sign for kidney health. The study also found that sparsentan maintained kidney function better than irbesartan.

Unlike the standard treatments for proteinuria after a kidney transplant, which often involve immunosuppressive drugs, sparsentan is unique because it is a non-immunosuppressive option. It works by dual antagonism of receptors ETAR and AT1R, offering a potent anti-proteinuric effect. Researchers are excited about sparsentan because of its potential to reduce proteinuria effectively without the side effects associated with immunosuppressants.

Research has shown that sparsentan can significantly reduce proteinuria, a common issue after a kidney transplant characterized by excess protein in the urine. In earlier studies, sparsentan lowered proteinuria by 62% after 14 weeks and maintained this reduction over time. It also resulted in more individuals experiencing partial or complete remission of proteinuria compared to other treatments. Sparsentan works by blocking two pathways that cause kidney damage, thereby reducing protein levels in the urine. These findings suggest sparsentan could be effective for individuals dealing with proteinuria after a kidney transplant.²⁶⁷⁸⁹