Travere Reports Positive Topline Interim Results from Phase 3 Study of Sparsentan in IgAN

Travere Therapeutics reported positive topline interim results from the ongoing pivotal phase 3 PROTECT study of sparsentan, an experimental drug candidate for the treatment of IgA nephropathy, in which the treatment group experienced 49.8 percent mean reduction of proteinuria from baseline after 36 weeks.

Photo: Eric Dube, CEO of Travere Therapeutics

IgA nephropathy (IgAN) is a kidney disorder that occurs when IgA (immunoglobulin A), a protein that helps the body fight infections, settles in the kidneys. IgA nephropathy can occur at any age, even in childhood. After many years, deposits of IgA may cause the kidneys to leak blood and sometimes protein in the urine. In the early stages, IgA nephropathy has no symptoms, and the first sign of this condition may be blood in the urine. After 10 to 20 years, the kidneys may show signs of damage and 20 to 40 percent of adults will develop end-stage kidney disease.

Although IgA nephropathy usually occurs in a family with no other affected members, several cases of familial IgA nephropathy have been reported. Familial IgA nephropathy is suspected to run through families in an autosomal dominant manner and is linked to genetic material on the long arm of chromosome 6. There is no cure for this condition and current treatment focuses on slowing the disease and preventing complications.

The PROTECT study met its pre-specified interim primary efficacy endpoint with statistical significance, demonstrating a greater than threefold reduction of proteinuria from baseline after 36 weeks of treatment, compared to the active control irbesartan. Preliminary results from the interim analysis suggest that to date in the study, sparsentan has been generally well-tolerated and consistent with the observed safety profile to date. Based on the results from the interim analysis, Travere plans to submit an application for accelerated approval in the United States in the first half of 2022 and also plans to submit an application for conditional marketing authorization in Europe.

“IgAN is a leading cause of end-stage kidney disease and there is a clear need for novel treatment options to slow the progression of this devastating rare kidney disorder,” said Eric Dube, CEO of Travere Therapeutics. “These data from the PROTECT study further demonstrate sparsentan’s ability to significantly reduce proteinuria and support its potential to become a new foundational treatment for people living with IgAN, if approved. We will continue our efforts to maintain high quality in this ongoing study, and we look forward to engaging with regulators as we prepare for accelerated approval submissions beginning in the first half of next year.”

Consistent with prior guidance, Travere is providing limited data from the interim analysis to maintain trial integrity in the ongoing study. In the PROTECT study, a total of 404 patients with persistent proteinuria despite active ACE or ARB treatment, were randomized 1:1 to receive once daily oral doses of either sparsentan or irbesartan, the active control. The study protocol provided for an unblinded interim analysis to evaluate the primary efficacy endpoint—the change in proteinuria (urine protein-to-creatinine ratio) from baseline at Week 36—approximately 36 weeks following randomization of the first 280 patients. After 36 weeks of treatment, patients receiving sparsentan achieved a mean reduction in proteinuria from baseline of 49.8 percent, compared to a mean reduction in proteinuria from baseline of 15.1 percent for irbesartan-treated patients.

“Sparsentan has now demonstrated in one of the largest interventional studies to date in IgAN, a statistically robust and clinically meaningful proteinuria reduction relative to a current standard of care,” said Noah Rosenberg, chief medical officer of Travere Therapeutics. “These data build upon our Phase 2 DUET and Phase 3 DUPLEX studies in FSGS and further strengthen the support for our novel approach with sparsentan as a dual endothelin-angiotensin receptor antagonist being developed for rare kidney disorders. I want to thank all the patients, their families, as well as the investigators and site staff who continue to participate in this ongoing landmark study in IgAN.”

Secondary efficacy endpoints include the rate of change in estimated glomerular filtration rate (eGFR) following the initiation of randomized treatment over 58-week and 110-week periods, as well as the rate of change in eGFR over 52-week and 104-week periods following the first six weeks of randomized treatment. The company believes that preliminary eGFR data available at the time of the interim analysis are indicative of a potential clinically meaningful treatment effect after two years of treatment. Per study protocol, patients will continue in a blinded manner in the PROTECT study to fully assess the treatment effect on eGFR slope over 110 weeks in the confirmatory endpoint analysis. Topline results from the confirmatory endpoint analysis are expected in the second half of 2023.

A preliminary review of the interim safety results indicates that to date in the study, both treatment groups were generally well tolerated, and sparsentan appeared consistent with the previously observed safety profile with no new safety signals emerging.

Travere also remains on track to provide a regulatory update on its pivotal phase 3 DUPLEX study of sparsentan for the treatment of focal segmental glomerulosclerosis (FSGS) during the third quarter of 2021.

Sparsentan has been granted Orphan Drug designation for the treatment of IgAN and FSGS in the United States and Europe.

Author: Rare Daily Staff