Diagnostic application of kidney allograft-derived absolute cell-free DNA levels during transplant dysfunction

Abstract

Graft‐derived cell‐free DNA (donor‐derived cell‐free DNA) is an emerging marker of kidney allograft injury. Studies examining the clinical validity of this biomarker have previously used the graft fraction, or proportion of total cell‐free DNA that is graft‐derived. The present study evaluated the diagnostic validity of absolute measurements of graft‐derived cell‐free DNA, as well as calculated graft fraction, for the diagnosis of graft dysfunction. Plasma graft‐derived cell‐free DNA, total cell‐free DNA, and graft fraction were correlated with biopsy diagnosis as well as individual Banff scores. Sixty‐one samples were included in the analysis. For the diagnosis of antibody mediated rejection, the receiver‐operator characteristic area under the curves of graft‐derived cell‐free DNA and graft fraction were 0.91 (95% CI 0.82‐0.98) and 0.89 (95% CI 0.79‐0.98), respectively. Both measures did not diagnose borderline or type 1A cellular mediated rejection. Graft fraction was associated with a broader range of Banff lesions, including lesions associated with cellular mediated rejection, while graft‐derived cell‐free DNA appeared more specific for antibody mediated rejection. Limitations of this study include a small sample size and lack of a validation cohort. The capacity for absolute quantification, and lower barriers to implementation of this methodology recommend it for further study.

Absolute quantification of donor-derived cell-free DNA as a marker of rejection and graft injury in kidney transplantation: Results from a prospective observational study

“…This is presumably because dd‐cfDNA(cp/mL), unlike dd‐cfDNA(%), is not affected by changes in recipient DNA present in the circulation. We, however, concur with Whitlam et al that considering both absolute quantification of dd‐cfDNA(cp/mL) and dd‐cfDNA fraction together may provide additional diagnostic information. The findings strengthen the evidence that dd‐cfDNA determinations after transplantation are useful to avoid unnecessary biopsies triggered by plasma creatinine elevations and to detect asymptomatic, subclinical graft damage, including from inadequate immunosuppression.…”

“…Elevation of dd‐cfDNA is not rejection specific, but reveals the degree of graft cell injury, complements histologic findings, and most importantly can help to avoid unnecessary biopsies, based on the high negative predictive value shown herein. As described by Whitlam and Bloom, we also observed elevations of dd‐cfDNA in patients with IF/TA. In general, results can be used to monitor individual responses to rejection treatments, to detect under‐immunosuppression (eg, noncompliance), and can be helpful to achieve personalized immunosuppression.…”

“…dd‐cfDNA(%) has recently been reported to be a sensitive, noninvasive biomarker of kidney transplant rejection superior to serum creatinine . Methods determining dd‐cfDNA(%), however, have the potential disadvantage of being affected by changes in the circulating recipient cfDNA . This limitation can be overcome by absolute quantification of dd‐cfDNA (eg, as genomic copies of dd‐cfDNA per mL of patient's plasma[cp/mL]).…”

Quantitative PCR of INDEL s to measure donor‐derived cell‐free DNA —a potential method to detect acute rejection in kidney transplantation: a pilot study

“…In contrast to Bloom's study, we were able to obtain ddcfDNA test results within 6–8 h using standard laboratory equipment. In 2018, Whitlam and colleagues reported on 61 kidney transplant recipients with for cause biopsies in the long‐term follow‐up (minimum 3 weeks after transplantation and up to 10 years), and determined ddcfDNA based on heterozygous copy number variation DNA sequences and droplet digital PCR . The group focused on chronic and acute ABMR, which was diagnosed in 13/61 patients.…”

Prognostic value of the donor‐derived cell‐free DNA assay in acute renal rejection therapy: A prospective cohort study

“…Cell‐free DNA (cfDNA) in plasma comes from physiological programmed cell death 10 and pathologically injured cells 11‐16 . Donor‐derived cfDNA (dd‐cfDNA) comes from the allograft and is considered a potential noninvasive marker for graft injury assessment 12,13,17‐21 . The diagnostic value of dd‐cfDNA analysis in solid organ transplantations has been reported in a number of studies 22,23 .…”