Using both the Fraction and Quantity of Donor-Derived Cell-Free DNA to Detect Kidney Allograft Rejection

Abstract

Early detection of allograft rejection is critical to the successful management of transplant recipients. Tissue biopsy has been the "gold standard" for diagnosis of active rejection (AR), but is invasive and has poor reproducibility. 1 Conventional noninvasive biomarkers, such as changes in serum creatinine, are available for detecting AR, but are limited due to low sensitivity and specificity. 2 Thus, there is a need for new noninvasive markers that have high accuracy for detecting AR.Donor-derived cell-free DNA fraction (dd-cfDNA[%]) is a promising noninvasive biomarker for detecting allograft rejection. However, dd-cfDNA(%) can be artificially depressed by high levels of circulating cfDNA, which can occur in patients who are obese, have had recent surgery, have medical complications, or received certain medications. 3 This can potentially lead to false negative results.Recently, two studies provided preliminary evidence indicating that the absolute quantity of dd-cfDNA may show better performance for detecting AR than dd-cfDNA(%). 4,5 In this study we present our results from an assay that utilizes a new two-threshold algorithm that combines both dd-cfDNA(%) and absolute quantity of dd-cfDNA (copies/ml), with the goal of increasing test sensitivity, particularly through improved detection in patients where cfDNA levels are high.

Donor-derived Cell-free DNA Shows High Sensitivity for the Diagnosis of Pancreas Graft Rejection in Simultaneous Pancreas-kidney Transplantation

“…We assessed the ability of 2 recently published thresholds in detecting kidney allograft rejection by applying (1) a cutoff of 1% dd-cfDNA, 14 and (2) a 2-threshold algorithm that combined the dd-cfDNA fraction cutoff (≥1%) and a dd-cfDNA quantity cutoff of ≥78 cp/mL. 24 Sensitivity using dd-cfDNA fraction alone was 28.6% (2/7). Sensitivity was considerably higher, at 57.1% (4/7), when using the 2-threshold algorithm that combines dd-cfDNA fraction and dd-cfDNA quantity.…”

A novel donor-derived cell-free DNA assay for the detection of acute rejection in heart transplantation

“…A “two-threshold” algorithm was employed, which combines a cutoff for dd-cfDNA fraction with a cutoff for absolute quantity of dd-cfDNA. 36 In the present study, a post-hoc analysis using dd-cfDNA quantity indicated that incorporation of this measure could increase the sensitivity of the assay. Finally, this study, and indeed most studies assessing novel tests for rejection, is limited by the use of EMB as the comparator.…”

Donor‐derived cell‐free DNA and renal allograft rejection in surveillance biopsies and indication biopsies

“…Similarly, a higher cutoff for the diagnosis of rejection, as suggested by some studies that showed higher median value (2.50%) of dd‐cfDNA fraction in patients with ABMR, would lead to an increase in false negative results 9 . More recently, the combination of the quantity of dd‐cfDNA threshold and the dd‐cfDNA fraction threshold has been suggested to improve sensitivity in the detection of active rejection in renal allograft patients 10 . Our analysis is limited by the overall small number of surveillance biopsies performed and the significant number of unacceptable dd‐cfDNA samples excluded from the analysis.…”

“…9 More recently, the combination of the quantity of dd-cfDNA threshold and the dd-cfDNA fraction threshold has been suggested to improve sensitivity in the detection of active rejection in renal allograft patients. 10 Our analysis is limited by the overall small number of surveillance biopsies performed and the significant number of unacceptable dd-cfDNA samples excluded from the analysis. Further large-scale studies are needed to confirm our findings.…”