Session Name: Biomarkers, Immune Assessment and Clinical Outcomes
Session Date & Time: None. Available on demand.
*Purpose: The TruGraf kidney blood gene expression test is a well-validated non-invasive biomarker to detect immune quiescence thus ruling out silent subclinical rejection in stable kidney transplant recipients, eliminating the need for a surveillance biopsy. The TruGraf test is a microarray-based assay that analyzes the peripheral blood gene expression profile (GEP) and provides a binary result of either TX (Transplant eXcellence) or not-TX (not Transplant eXcellence). A TruGraf TX result correlates with a high degree of confidence (NPV 89%) to a surveillance biopsy result showing no evidence of rejection. Given this intended context of use, TruGraf validation was performed exclusively in cohorts of patients that have a stable renal function defined as SCr <2.3 or <20% increase as compared to the average of previous 3 SCr results. The intent of this study was to evaluate performance in the setting of unstable kidney function (AKI) and for-cause biopsies.
*Methods: This is a retrospective evaluation of serial TruGraf gene expression testing done on 10 patients with evidence of AKI (SCr >2.3 or >20% increase over the average of previous 3 SCr values). From Dec 2019 to Jun 2020, a total of 23 tests were drawn on these patients as an adjunct to clinical and laboratory assessment.
*Results: Of the 23 TruGraf tests done, 13 (56%) were a TX result while 10 (43%) were a not-TX result. There was a total of 11 biopsies done on 9 patients with the majority of biopsies (n=9) being done within 2 weeks of the TruGraf test date. One patient with a TX result did not have a biopsy done during this observation period. The GEP result of TX or Not-TX correlated with biopsy results in 10 of the 11 samples. Of these 10 biopsy results, a TX result was consistent with no rejection on biopsy (n=4). The Not-TX result (n=6) correlated with positive biopsies with histology for borderline rejection (n=1), mixed TCRM/AMR (n=2), AMR (n=2), and TCMR (n=1). In the single sample with a false negative TX result, the patient’s biopsy was positive for AMR with C4d2, PTC-. The performance metrics in this patient population were: sensitivity 85.71%, specificity 100%, and accuracy 90.91%.
*Conclusions: As expected, the TruGraf GEP analysis is consistent along the continuum of rejection and is inclusive of both subclinical and clinical acute rejection. While limited by a small sample size, the TruGraf test has a high degree of accuracy in the setting of AKI and appears to have stronger performance as compared to the context of stable kidney function.
To cite this abstract in AMA style:Singh N, Naseer MS, Aultman D, Shokouh-Amiri H, Zibari G. Trugraf Gene Expression Testing Can Discriminate Rejection in the Setting of Acute Kidney Injury [abstract]. Am J Transplant. 2021; 21 (suppl 3). https://atcmeetingabstracts.com/abstract/trugraf-gene-expression-testing-can-discriminate-rejection-in-the-setting-of-acute-kidney-injury/. Accessed June 11, 2021.
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