Single center experience comparing two clinically available donor derived cell free DNA tests and review of literature

The introduction of assays for donor-derived cell-free DNA into clinical transplant medicine has provided an additional method to assess allograft health. We compared the performance of two of these assays, Prospera™ and AlloSure®. A series of 15 paired-samples from individual kidney transplant recipients were tested using both Prospera™ and AlloSure® assays simultaneously. Test performances were determined using the company cutoff of >1% to indicate active rejection. Additional analysis was also performed using a cutoff of 0.5%. Acute rejections were all confirmed by biopsy. There was one discordant result for 15 paired-samples when using a cutoff level of 1%, and results were concordant using a cutoff level of 0.5%. Seven biopsy were performed, six of which showed rejection. Using cutoff of 1%, Prospera™ identified 80% (4/5) of T cell-mediated rejections (TCMR) compared to 60% for AlloSure® (3/5). Both assays recognized the only case of antibody-mediated rejection. When using cutoff level of 0.5%, both assays correctly identified all cases of rejection. In this cohort, the two tests showed different sensitivities when using the validated cutoff of 1% dd-cfDNA, and the same sensitivity when using a lower cutoff of 0.5%. The result accuracy was confirmed by kidney biopsy.