Comparing plasma donor-derived cell-free DNA to gene expression in endomyocardial biopsies in the Trifecta-Heart study.

Background. Plasma donor-derived cell-free DNA (dd-cfDNA) is used to screen for rejection in heart transplants. We launched the Trifecta-Heart (ClinicalTrials.gov #NCT04707872), an investigator-initiated, prospective trial, to examine the correlations between genome-wide molecular changes in endomyocardial biopsies (EMBs) and plasma dd-cfDNA. The present report analyzes the correlation of plasma dd-cfDNA with the gene expression in EMBs from 4 vanguard centers and compared these correlations with those in 604 kidney transplant biopsies in the Trifecta-Kidney study (ClinicalTrials.gov #NCT04239703). Results. Top transcripts correlating with dd-cfDNA were related to genes increased in rejection such as IFNG-inducible genes (e.g., HLA-DMA), but also with genes induced by injury and expressed in macrophages (e.g., SERPINA1, HMOX1). In gene enrichment analysis, the top dd-cfDNA-correlated genes reflected inflammation and rejection pathways. Dd-cfDNA correlations with rejection genes in EMB were similar to those seen in kidney transplant biopsies, with somewhat stronger correlations for TCMR genes in hearts and ABMR genes in kidneys. However, the correlations with parenchymal injury-induced genes and macrophage genes were much stronger in hearts. Conclusions: In heart transplants in the Trifecta-Heart study, dd-cfDNA correlates significantly with molecular rejection but also with injury and macrophage infiltration, reflecting the proinflammatory properties of injured cardiomyocytes. The relationship supports the utility of dd-cfDNA in the clinical management of heart transplant recipients. Methods. We analyzed 137 consecutive dd-cfDNA-EMB pairs from 70 patients. Plasma %dd-cfDNA was measured by the ProsperaTM test (Natera, Inc.), and gene expression in EMBs was assessed by Molecular Microscope® Diagnostic System (MMDx) using machine-learning algorithms to interpret rejection and injury states.