Cell-Free DNA and Active Rejection in Kidney Allografts

Abstract

Histologic analysis of the allograft biopsy specimen is the standard method used to differentiate rejection from other injury in kidney transplants. Donor-derived cell-free DNA (dd-cfDNA) is a noninvasive test of allograft injury that may enable more frequent, quantitative, and safer assessment of allograft rejection and injury status. To investigate this possibility, we prospectively collected blood specimens at scheduled intervals and at the time of clinically indicated biopsies. In 102 kidney recipients, we measured plasma levels of dd-cfDNA and correlated the levels with allograft rejection status ascertained by histology in 107 biopsy specimens. The dd-cfDNA level discriminated between biopsy specimens showing any rejection (T cell-mediated rejection or antibody-mediated rejection [ABMR]) and controls (no rejection histologically), P,0.001 (receiver operating characteristic area under the curve [AUC], 0.74; 95% confidence interval [95% CI], 0.61 to 0.86). Positive and negative predictive values for active rejection at a cutoff of 1.0% dd-cfDNA were 61% and 84%, respectively. The AUC for discriminating ABMR from samples without ABMR was 0.87 (95% CI, 0.75 to 0.97). Positive and negative predictive values for ABMR at a cutoff of 1.0% dd-cfDNA were 44% and 96%, respectively. Median dd-cfDNA was 2.9% (ABMR), 1.2% (T cell-mediated types $IB), 0.2% (T cellmediated type IA), and 0.3% in controls (P=0.05 for T cell-mediated rejection types $IB versus controls). Thus, ddcfDNA may be used to assess allograft rejection and injury; dd-cfDNA levels ,1% reflect the absence of active rejection (T cell-mediated type $IB or ABMR) and levels .1% indicate a probability of active rejection.

Noninvasive detection of graft injury after heart transplant using donor-derived cell-free DNA: A prospective multicenter study

“…11 Differences in baseline dd-cfDNA levels may reflect differences in the rate of cell turnover within the allograft. This is in contrast to stable kidney transplant recipients, in whom dd-cfDNA is detected at a median of 0.21% by using the AlloSure ® assay.…”

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

“…1 Total cfDNA levels may rise in a variety of physiologic and pathologic states. [4][5][6] To date, there has been one large published prospective clinical study evaluating the diagnostic validity of plasma gd-cfDNA for allograft dysfunction in kidney transplantation. 2,3 Higher levels of total cfDNA have been associated with increased severity or poorer prognosis in some of these diseases.…”

“…These include exercise, malignancy, sepsis, myocardial infarction, stroke, and critical illness. 6 A possible limitation of the method raised by this group is the potential for confounding of graft fraction by concurrent elevations in total cfDNA, an issue also observed in noninvasive prenatal testing. 2,3 In transplantation, it has been proposed that injury to the allograft results in increased release of gd-cfDNA into recipient plasma via graft-cell apoptosis and necrosis.…”

Repeat kidney transplant recipients with active rejection have elevated donor-derived cell-free DNA

“…In this study, we evaluated the dd-cfDNA in patients with more than one kidney transplant. 4 We also examined dd-cfDNA levels in all 11 RKTR patients (9 In RKTRs, at the time of clinically indicated biopsies, dd-cfDNA is significantly higher in patients with biopsy-proven rejection than in patients without rejection. These cohorts were drawn from the Circulating Donor-Derived Cell-Free DNA in Blood for Diagnosing Acute Rejection in Kidney Transplant Recipients (DART) study (ClinicalTrials.gov Identifier: NCT02424227), 4 where surveillance for rejection began less than 2 months posttransplant and there was no clinically indicated biopsy at the first visit and no rejection while on the study.…”