Abstract: FR-PO0805
Sparsentan Slows the Loss of Kidney Function in Patients with IgAN: Post Hoc Analyses of the Phase 3 PROTECT Study
Session Information
- Glomerular Clinical Trials: From Data to Impact
November 07, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1402 Glomerular Diseases: Clinical, Outcomes, and Therapeutics
Authors
- Roll, Matthias, Vifor Pharma Deutschland GmbH, Munich, BY, Germany
- Hardt, Thomas, Vifor Pharma Deutschland GmbH, Munich, BY, Germany
- Gladbach, Amadeus, Vifor Pharma Deutschland GmbH, Munich, BY, Germany
- Floege, Jürgen, Universitätsklinikum Aachen, Med. Klinik II, Nephrologie u. Klinische Immunologie, Aachen, Germany
Background
Primary immunoglobulin A nephropathy (IgAN) is a rare immune-mediated glomerular disease, with a median age of diagnosis of around 40 years. Up to 40% of patients progress to end-stage renal disease within 20 years of diagnosis. Sparsentan (SPAR) is a novel dual endothelin-angiotensin receptor antagonist. This post -hoc analysis compares the efficacy of SPAR vs. irbesartan (IRB) in preventing the progression to chronic kidney disease (CKD) stages 4 or 5 and was conducted as part of the HTA process in Germany.
Methods
The randomized, double-blind, active-controlled, multicenter Phase III PROTECT study examined the efficacy and safety of SPAR (n=202) vs. maximum-dose IRB (n=202) in adult patients with biopsy-proven IgAN over 110 weeks. As a study inclusion criterion, patients had to have CKD stage 1-3 at screening. However, some patients progressed to CKD stage 4 prior to baseline visit (SPAR n=15, IRB n=5). Here we analyze the proportion of patients who progressed to CKD stages 4 or 5 by Week 110 and the time to reach CKD stages 4 or 5. The entire study population (CKD 1-4) as well as patients with CKD stages 1-3 at baseline (CKD 1-3) were analyzed.
Results
Statistically fewer patients treated with SPAR reached CKD stages 4 or 5 compared to IRB. Moreover, the time to reach CKD stages 4 or 5 was statistically significantly longer under SPAR treatment. This treatment benefit of SPAR was demonstrated for patients with CKD stages 1-4 as well as for patients with CKD stages 1-3 at baseline (Table 1).
Conclusion
This post hoc analysis confirms the effect of SPAR on the clinically relevant parameter eGFR: SPAR effectively slows down the loss of renal function compared to IRB. Statistically significantly fewer patients progress to CKD stages 4 or 5 under SPAR, and the time to reach CKD stages 4 or 5 is prolonged —an effect outcome that was accepted as patient-relevant in the German HTA process and led to an evidence-based additional benefit.
Table 1: Patients with CKD stages 4 or 5 until Week 110
| CKD stage at baseline | SPAR n/N (%) | IRB n/N (%) | Patients with CKD 4/5 RR [95% CI] | Patients with CKD 4/5 p value | Time to reach CKD 4/5 HR [95% CI] | Time to reach CKD 4/5 p value |
| CKD 1-4 | 47/202 (23.3) | 65/202 (32.2) | 0.731 [0.555, 0.964] | 0.026 | 0.666 [0.458, 0.971] | 0.034 |
| CKD 1-3 | 43/187 (23.0) | 65/197 (33.0) | 0.735 [0.558, 0.969] | 0.029 | 0.672 [0.457, 0.989] | 0.044 |
Funding
- Commercial Support – Vifor Pharma Deutschland GmbH