Kidney Week

Abstract: FR-PO1234

Clinical Application of PIRCHE Scores: Reclassifying Immunologic Risk in Patients with Medium Eplet Mismatch

Session Information

• Transplantation: Clinical - Rejection, Biomarkers, and Pharmacology
  October 23, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Transplantation

• 2002 Transplantation: Clinical

Authors

• Molnar, Miklos Zsolt, University of Rochester Medical Center, Rochester, New York, United States

Miklos Zsolt Molnar, MD, PhD, FASN

• Holdaway, Kendon J., University of Utah Health, Salt Lake City, Utah, United States

Kendon J. Holdaway

• Raghavan, Divya, University of Utah Health, Salt Lake City, Utah, United States

Divya Raghavan, MD

• Marineci, Silviana, University of Utah Health, Salt Lake City, Utah, United States

Silviana Marineci, MD

• Toth, Fruzsina, University of Utah Health, Salt Lake City, United States

Fruzsina Toth, MD

• Fornadi, Katalin, University of Utah Health, Salt Lake City, Utah, United States

Katalin Fornadi, MD, PhD

• Niemann, Matthias, Pirche AG, Grünwald, BY, Germany

Matthias Niemann, MSc

Background

Molecular histocompatibility assessment using eplet mismatch and Predicted Indirectly ReCognizable HLA Epitopes (PIRCHE) scores has improved immunologic risk stratification in kidney transplantation. However, its clinical implementation remains limited, particularly for medium eplet mismatch donor–recipient pairs.

Methods

In this single-center retrospective cohort study, we evaluated 493 adult kidney transplant recipients transplanted between 2021 and 2024. Eplet mismatch was categorized based on Wiebe/Nickerson criteria, and medium mismatch pairs were further stratified using PIRCHE-T2 and PIRCHE-B scores. The primary outcome was early allograft injury within one year, defined as a composite of donor-specific antibody (DSA) development, histologic or molecular rejection, or elevation of donor-derived cell-free DNA (dd-cfDNA). Associations were assessed using Cox proportional hazards models and Kaplan–Meier analyses.

Results

Zero and low eplet mismatch groups had similar outcomes and were combined as the low-risk reference group. Compared with this group, medium eplet mismatch was associated with increased risk of early allograft injury (adjusted hazard ratio [aHR] 2.44, 95% confidence interval [CI] 1.41–4.23), rejection (aHR 7.47, 95% CI 2.07–26.91), and elevated dd-cfDNA (aHR 4.83, 95% CI 1.70–13.75), while high mismatch conferred greater risk (aHR 5.17, 95% CI 2.86–9.33). Among medium mismatch recipients, ~20% were reclassified as medium–low risk based on PIRCHE scores and had outcomes comparable to the low-risk group (aHR 1.87, 95% CI 0.92–3.81), with no differences in DSA, rejection, or dd-cfDNA (Figure).

Conclusion

Medium-low immunologic risk, defined by medium eplet mismatch with low PIRCHE scores, is associated with outcomes comparable to zero/low eplet mismatch transplantation. These findings support the simultaneous use of multiple molecular matching algorithms to refine risk stratification and expand donor options for patients requiring low immunologic risk transplantation.

Acknowledgment

This study was approved by the University of Utah Institutional Review Board (#IRB_00162331).

Funding

• Private Foundation Support