A two-threshold algorithm using donor-derived cell-free DNA fraction and quantity to detect acute rejection after heart transplantation
Paul Kim, M. Olympios, Konstantinos Sideris, Eleni Tseliou, Taylor Y. Tran, Spencer Carter, Alison Brann, Navchetan Kaur, Sandra Carey, Sangeeta Bhorade, Yen-An Chen, David K. A. Barnes, Ebad Ahmed, Jing Xie, Adam Prewett, Matthew Rabinowitz, Bernhard Zimmermann, Michelle S. Bloom, Zachary Demko, Eric Adler, Josef Stehlik
Abstract
Donor-derived cell-free DNA (dd-cfDNA) is a promising biomarker of acute rejection (AR) after heart transplantation (HTx). dd-cfDNA measured as a fraction of total cfDNA can be affected by changes in total cfDNA whereas dd-cfDNA quantity can mitigate this impact. This study investigates the performance of a two-threshold algorithm (2TA) that combines dd-cfDNA fraction (dd-cfDNA%) and donor-quantity score (DQS). A total of 808 plasma samples were prospectively collected for dd-cfDNA testing from 187 adult HTx patients with contemporaneous endomyocardial biopsies. cfDNA was analyzed by a single nucleotide polymorphism (SNP)-based next-generation sequencing workflow; dd-cfDNA% and DQS were measured using the sequencing reads and SNP genotypes. Both dd-cfDNA% and DQS were significantly higher in AR compared to non-AR samples (p<10 -14 ). Considering samples exceeding either dd-cfDNA%=0.26% or DQS=18 cp/mL as positive, the 2TA demonstrated 86.5% sensitivity and 83.6% specificity for AR detection and an AUC of 0.881. Compared to dd-cfdNA% alone, performance improved with a mean net reclassification index (NRI) of 16.4% (SD: 4.0%; p=0.015) and a 37.3% reduction of the false positive rate compared to the previously established cutoff of 0.15%. Combining dd-cfDNA fraction and quantity estimate in a 2TA may improve AR detection accuracy in HTx recipients compared to dd-cfDNA% alone.