Departmental sources
Background:TruGraf is a blood-based biomarker test that measures differential expression of a collection of genes that have been shown to correlate with surveillance biopsy results. However, in the majority of U.S. transplant centers, surveillance biopsies are not performed. The objectives of this study were to evaluate the clinical validity of TruGraf in stable kidney transplant recipients and to demonstrate the potential clinical utility of serial TruGraf testing in a center not utilizing surveillance biopsies.
Material/Methods:Serum creatinine levels, TruGraf testing at multiple time points, and subsequent clinical follow-up were obtained for 28 patients.
Results:Overall concordance of TruGraf results, when compared with independent clinical assessment of testing, was 77% (54/70) for all tests; 79% (22/28) for test 1, 75% (21/28) for test 2, and 79% (11/14) for test 3. The negative predictive value (NPV) was 98.0%. Analysis of clinical utility indicated that 77% of TruGraf results would have been useful in patient management.
Conclusions:Our results indicate the value of serial TruGraf testing in those transplant centers that do not perform surveillance biopsies as part of their standard of care. The high negative predictive value indicates the ability of TruGraf to confirm immune quiescence with a high degree of probability in patients with a Transplant eXcellence (TX) result, without the need to perform a surveillance biopsy.
Purpose
TruGraf™ blood test measures a specific gene expression signature in peripheral blood mononuclear cells for noninvasive assessment of kidney transplant recipients (KTRs) with stable renal function, excluding subclinical acute rejection (subAR) with high degree of confidence. Study objective was to correlate TruGraf™ test with 6‐month surveillance biopsy (SBx).
Methods
Prospective, single‐center study of 116 consecutive KTRs with SBx performed at 6 months post‐transplant..TruGraf™ done at time of SBx; results compared with histology (Banff 2017) for concordance.
Results
Of 116 enrollees, 26 excluded, absent biopsy (n = 17), test quality control issues (n = 9), leaving 90 KTRs—66% deceased donor kidneys, 58% African American, and 59% male. TruGraf™ result negative in 67 subjects; 54 had normal biopsy, indicating SBx could have been avoided. Eight subjects had true positive result where biopsy justified. Unnecessary biopsy would have been performed in 15 subjects with false‐positive TruGraf™, and subAR missed in 13 subjects with false‐negative test. In overall population of 90 patients, SBx would have been avoided in 54 (60%).
Conclusions
Implementation of TruGraf™ testing in a “real‐world” cohort at the time of SBx identified a significant proportion of KTRs that could have avoided SBx.
DiscussionMolecular biomarkers have been studied in the graft, urine and blood of kidney transplant recipients [11][12][13][14][15]. DNA microarrays have been used to analyze tissue biopsies of kidney transplant
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