FOCAL segmental glomerulosclerosis (FSGS) is a rare kidney disease, characterised by proteinuria, and is estimated to affect around 40,000 people in the USA. With no FSGS treatment currently approved, the results from a Phase II trial investigating the effects of a new drug, sparsentan, could signify a watershed moment in the treatment of a specific subset of kidney disorder.
Researchers from the School of Medicine, New York University, New York City, New York, USA recruited 109 FSGS patients from the USA and Europe (USA participants aged 8–75 years and European Participants aged 18–75 years) across 44 centres. The participants were randomised to receive either an escalating dose of sparsentan (200, 400, or 800 mg) or 300 mg of the current standard angiotensin II blocker irbesartan per day over 8 weeks. “This is the first large-scale clinical trial of a treatment specifically to target FSGS,” explained study lead Pro Howard Trachtman, New York University, Now York City, New York, USA.
Sparsentan was found to be more effective than irbesartan at limiting tissue scarring with very few serious side effects, the most common being low blood pressure, dizziness, and swelling, which were seen in both treatment groups.
Like irbesartan, sparsentan is an angiotensin II blocker, but the new drug also inhibits endothelin receptor type A. The two inhibitory mechanism are thought to function collaboratively to reduce the production of scar inducing proteins. Further studies are required to determine the long-term effects of sparsentan, and with the Phase III DUPLEX study actively recruiting patients these answers could well be at hand. Prof Trachtman concluded: “Not only could sparsentan become part of the standard of care for patients with FSGS, but there are potential implications for any patient with kidney disease characterised by proteinuria, including the more common IgA nephropathy, which affects hundreds of thousands of people worldwide.”
