Abstract 15272: What's in a Name: Comparison of Dd-cfDNA Technologies Following Heart Transplantation

Abstract

Introduction: Little is known about the comparative differences between the Allosure (CareDx) and Prospera (Natera) donor derived cell-free DNA (dd-cfDNA) assays following heart transplantation. Methods: A retrospective analysis of all patients that had both dd-cfDNA assays simultaneously performed between February 2022 and December 2023 were reviewed. A total of 233 samples obtained between 18 to 506 days post-transplant from 46 patients were reviewed. Agreement between Allosure and Prospera assays were compared utilizing their thresholds indicative of an abnormality of 0.12% (Allosure) and 0.15% (Prospera). Results: Baseline patient characteristics include median age 60 years and 59% male. There were a total of 12 biopsy specimens available with both dd-cfDNA assays. There was substantial agreement between both dd-cfDNA assays (91% agreement, Cohens kappa 0.75). Both dd-cfDNA assays were correctly suggestive of rejection when biopsy was available. Differences in elevations of dd-cfDNA were noted in cases outside of rejection and were not consistent in 20/233 samples when utilizing their cutoff values of 0.12% for Allosure and 0.15% for Prospera (McNemar’s p = 0.01)(Table 1). This discordance was due to increased classification of abnormal results with the lower threshold value for Allosure. When using identical threshold values of 0.12% or 0.15% for the two assays, this discordance is no longer present (p = 0.82 and p = 1.00, respectively). Conclusions: Both dd-cfDNA assays can be utilized for surveillance of rejection following heart transplantation. Understanding differences between the two assays is important and requires further larger studies to validate these preliminary findings.