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Kidney Week

Abstract: PO2175

Evolving Experience with TruGraf® Gene Expression Profile and TRAC™ Donor-Derived Cell-Free DNA Testing in Kidney Transplantation: First Year Post Transplant and Beyond

Session Information

Category: Transplantation

  • 1902 Transplantation: Clinical

Authors

  • Paramasivam, Vijayakumar, Baystate Medical Center, Springfield, Massachusetts, United States
  • Greco, Barbara A., Baystate Medical Center, Springfield, Massachusetts, United States
  • Germain, Michael J., Baystate Medical Center, Springfield, Massachusetts, United States
Background

Non-invasive validated rejection biomarkers are available to monitor kidney transplant recipients (KTR). Our program has replaced 3 and 12 month protocol biopsies (BX) with biomarker surveillance using TruGraf (TG) gene expression profile (GEP) validated to rule out subclinical acute rejection (subAR) and TRAC donor derived cell free DNA (dd-cfDNA) as a marker of allograft injury. This is the evolving single center experience of TruGraf-TRAC surveillance for KTR within the 1st year post-transplant (post-txp) and beyond

Methods

Our immunosuppression (IS) protocol is alemtuzumab with tacrolimus maintenance, mycophenolate mofetil added in high risk KTR. TG and TRAC were done at 3, 12 months post-txp, and with IS changes (mTORi/belatacept conversion, IS decrease). Additionally, all KTR to be tested at least once to determine baseline status (immune quiescence). A positive (pos) TG, TRAC, or dynamic changes in post-op course prompts further evaluation and/or repeat TG/TRAC testing PRN. BX were done in cases with equipoise. Donor specific antibodies (DSA) tested in all patients.

Results

To date, 115 KTRs surveilled with TG and/or TRAC (149 TG and 90 TRAC tests). 30/41 KTR spared 3-month BX. Of 11 BX, 6 were for delayed/slow graft function (negative (neg) TG (Transplant eXcellence (TX)) and neg for acute rejection/DSA) and 5 were for pos TG (not-TX) with 3 neg for DSA/acute rejection. 12/16 KTRs avoided 1-year BX. 45 KTRs were > 1 year post-txp at testing (16 KTR > 10 years, 8 KTR >20 years). Table 1: TG/TRAC concordance (n=82). 45% concordant neg, confirming IS adequacy. 50% discordant (TG or TRAC pos) prompting eval and correlation with findings (DSA, proteinuria, renal function). 5% concordant pos prompting BX, diagnosis, and/or subAR treatment.

Conclusion

Non-invasive TruGraf GEP with TRAC dd-cfDNA spares protocol BX in KTR at 3 and 12 months, while providing enhanced monitoring >1 year post-txp by ruling out subAR and assuring IS adequacy. Combined TruGraf and TRAC testing is promising, warranting larger studies for optimal synergy/frequency of serial testing, especially as subAR persists beyond the 1st year post-txp.

TruGraf-TRAC Concordance
KTR (n=82)TruGraf neg (TX)TruGraf pos (not-TX)
TRAC neg (<0.7%)3716
TRAC pos (≥0.7%)254