As reported on PharmaBiz, Renalys Pharma has reported encouraging topline data from its Phase III trial evaluating sparsentan (RE-021), an oral dual endothelin and angiotensin II receptor antagonist, in Japanese patients with IgA nephropathy (IgAN). The study demonstrated a significant reduction in proteinuria, with a least-squares geometric mean decrease of nearly 59% in the urine protein-to-creatinine ratio after 36 weeks of treatment. Safety findings were consistent with global trials, and no new risks were identified in the Japanese cohort.
The trial, conducted as a bridging study in collaboration with Japan’s PMDA, included both adult and pediatric patients aged 10 and older. Results mirrored international data, reinforcing sparsentan’s efficacy across age groups. Renalys plans to file a New Drug Application in Japan in 2026 to address the country’s substantial unmet need for IgAN therapies.
Sparsentan, marketed as Filspari in the U.S. and Europe, is already approved for slowing kidney function decline in adults with IgAN at risk of progression. Global studies, including the PROTECT trial, have shown the drug significantly reduces proteinuria and preserves kidney function compared to irbesartan. Beyond IgAN, sparsentan is being investigated for other rare kidney disorders such as FSGS and Alport syndrome, with potential broader applications in chronic kidney disease.
IgA nephropathy remains a leading cause of kidney failure in Japan, where treatment options are limited. Experts view these results as a critical step toward improving outcomes for patients with rare renal diseases.
