Rare Disease Day 2026: Kidney Diseases Enter Optimistic Therapeutic Era

On Rare Disease Day 2026, 4 clinicians share their insights and perspectives on the groundbreaking improvements in the rapidly evolving field of rare kidney diseases.

Despite persistent awareness gaps in rare kidney disease care, a wave of FDA approvals and phase 3 trial successes in IgA nephropathy (IgAN) and C3 glomerulopathy, (C3G) alongside updated 2025 KDIGO Practice Guidelines, has fueled growing clinician optimism about a rapidly advancing, disease-modifying treatment era.^1,2

Rare kidney diseases remain complex and underrecognized, leaving both patients and clinicians with challenges in early diagnosis, risk stratification, and long-term management. Yet recent scientific advances and regulatory approvals are beginning to reshape the therapeutic landscape.

Momentum in rare kidney disease care has accelerated with multiple FDA approvals supported by pivotal clinical trial data. In IgAN, budesonide demonstrated significant reductions in proteinuria and preservation of kidney function in the NefIgArd trial, while sparsentan, a dual endothelin-angiotensin receptor antagonist, showed positive outcomes in the PROTECT study. The addition of atrasentan, an endothelin A receptor antagonist, further underscores the diversification of therapeutic strategies in IgAN, with the ALIGN Phase III trial demonstrating clinically meaningful reductions in proteinuria, a key surrogate for slowing disease progression. Iptacopan, a factor B inhibitor targeting the alternative complement pathway, reported encouraging efficacy in the APPLAUSE-IgAN trial, highlighting a precision-based approach to treatment.^3,4,5

In C3G, iptacopan also showed promising results in the APPEAR-C3G trial, alongside other complement-targeted therapies such as pegcetacoplan and danicopan, reflecting growing opportunities for disease modification in a previously limited treatment space.^6,7,8

These advances are complemented by the updated 2025 KDIGO Practice Guidelines, which provide evidence-based recommendations to support clinicians in diagnosis, monitoring, and treatment selection, fostering a more standardized and patient-centered approach.

Together, these therapies, spanning endothelin-angiotensin signaling modulation, complement inhibition, and targeted anti-inflammatory strategies, illustrate a shift toward precision medicine in rare kidney disease.

Editor's Note: Norouzi reports relevant disclosures with Calliditas, Travere, Apellis, and others. Appel reports relevant disclosures with Novartis, Travere Therapeutics, and others. Russo reports no relevant disclosures. Arora declares no relevant disclosures.Reference

1. 6 New Kidney Disease Medications Approved in 2025. National Kidney Foundation. Published January 21, 2026. https://www.kidney.org/news-stories/6-new-kidney-disease-medications-approved-2025

2. Sayna Norouzi, MD, Cheung K, Skolnik E, Peleg Y. 2025 KDIGO Guideline Update for IgAN. Hcplive.com. Published January 14, 2026. Accessed February 28, 2026. https://www.hcplive.com/view/2025-kdigo-guideline-update-for-igan

3. Perkovic V, Barratt J, Rovin BH, et al; APPLAUSE‑IgAN Investigators. Alternative complement pathway inhibition with iptacopan in IgA nephropathy. N Engl J Med. 2025;392(6):531‑543. doi:10.1056/NEJMoa2410316. Published online 2024 Oct 25.

4. Kavanagh D, Bomback AS, Vivarelli M, et al. Oral iptacopan therapy in patients with C3 glomerulopathy: a randomized, double‑blind, placebo‑controlled, phase 3 study. Lancet. 2025;406(10512):1587‑1598. doi:10.1016/S0140‑6736(25)01148‑1.

5. Lafayette R, et al; NefIgArd Investigators. Efficacy and safety of a targeted‑release formulation of budesonide in patients with primary IgA nephropathy (NefIgArd): 2‑year results from a randomized phase 3 trial. Lancet. 2023; (Publication details).

6. KDIGO IgAN and IgA Vasculitis Work Group; Rovin BH, Barratt J, Cook HT, et al. KDIGO 2025 Clinical Practice Guideline for the Management of Immunoglobulin A Nephropathy (IgAN) and Immunoglobulin A Vasculitis (IgAV). Kidney Int. 2025;108(4S):S1‑S71. doi:10.1016/j.kint.2025.04.004.

7. Novartis Pharmaceuticals Corporation. Novartis receives FDA accelerated approval for Fabhalta (iptacopan), the first and only complement inhibitor for reduction of proteinuria in adults with primary IgA nephropathy. Press release; Aug 7, 2024.

8. Novartis Pharmaceuticals Corporation. Novartis investigational atrasentan Phase III study demonstrates clinically meaningful proteinuria reduction in patients with IgA nephropathy (ALIGN). Press release; May 25, 2024.