Relationship between donor-derived cell-free DNA and tissue-based rejection-related transcripts in heart transplantation

Dae Hyun Lee; Ahsan Usmani; Robby Wu; Tammi Wicks; Caroline Y Noh; Ryan Burke; Vani Ravichandran; Theresa Wolf-Doty; Ioana Dumitru; Guilherme H Oliveira; Peter Berman; Benjamin Mackie

doi:10.1016/j.healun.2024.02.011

Relationship between donor-derived cell-free DNA and tissue-based rejection-related transcripts in heart transplantation

J Heart Lung Transplant. 2024 Feb 17:S1053-2498(24)00055-X. doi: 10.1016/j.healun.2024.02.011. Online ahead of print.

Authors

Affiliations

¹ Heart Transplant Program, Transplant Institute, Tampa General Hospital, Tampa, Florida; Division of Cardiovascular Medicine, Department of Internal Medicine, University of South Florida Morsani College of Medicine, Tampa, Florida; Heart & Vascular Institute, Tampa General Hospital, Tampa, Florida. Electronic address: daehyunlee@usf.edu.
² Morsani College of Medicine, University of South Florida, Tampa, Florida.
³ Heart Transplant Program, Transplant Institute, Tampa General Hospital, Tampa, Florida; Division of Cardiovascular Medicine, Department of Internal Medicine, University of South Florida Morsani College of Medicine, Tampa, Florida; Heart & Vascular Institute, Tampa General Hospital, Tampa, Florida.
⁴ Heart Transplant Program, Transplant Institute, Tampa General Hospital, Tampa, Florida; Heart & Vascular Institute, Tampa General Hospital, Tampa, Florida.
⁵ Department of Pediatrics, Children's Hospital Los Angeles, USC Keck School of Medicine, Los Angeles, California.
⁶ CareDx, San Francisco, California.
⁷ Heart Transplant Program, Transplant Institute, Tampa General Hospital, Tampa, Florida; Division of Cardiovascular Medicine, Department of Internal Medicine, University of South Florida Morsani College of Medicine, Tampa, Florida; Heart & Vascular Institute, Tampa General Hospital, Tampa, Florida. Electronic address: bmackie@tgmg.org.

PMID: 38373559
DOI: 10.1016/j.healun.2024.02.011

Abstract

Background: Endomyocardial biopsy (EMB)-based traditional microscopy remains the gold standard for the detection of cardiac allograft rejection, despite its limitation of inherent subjectivity leading to inter-reader variability. Alternative techniques now exist to surveil for allograft injury and classify rejection. Donor-derived cell-free DNA (dd-cfDNA) testing is now a validated blood-based assay used to surveil for allograft injury. The molecular microscope diagnostic system (MMDx) utilizes intragraft rejection-associated transcripts (RATs) to classify allograft rejection and identify injury. The use of dd-cfDNA and MMDx together provides objective molecular insight into allograft injury and rejection. The aim of this study was to measure the diagnostic agreement between dd-cfDNA and MMDx and assess the relationship between dd-cfDNA and MMDx-derived RATs, which may provide further insight into the pathophysiology of allograft rejection and injury.

Methods: This is a retrospective observational study of 156 EMB evaluated with traditional microscopy and MMDx. All samples were paired with dd-cfDNA from peripheral blood before EMB (up to 9 days). Diagnostic agreement between traditional histopathology, MMDx, and dd-cfDNA (threshold of 0.20%) was compared for assessment of allograft injury. In addition, the relationship between dd-cfDNA and individual RAT expression levels from MMDx was evaluated.

Results: MMDx characterized allograft tissue as no rejection (62.8%), antibody-mediated rejection (ABMR) (26.9%), T-cell-mediated rejection (TCMR) (5.8%), and mixed ABMR/TCMR (4.5%). For the diagnosis of any type of rejection (TCMR, ABMR, and mixed rejection), there was substantial agreement between MMDx and dd-cfDNA (76.3% agreement). All transcript clusters (group of gene sets designated by MMDx) and individual transcripts considered abnormal from MMDx had significantly elevated dd-cfDNA. In addition, a positive correlation between dd-cfDNA levels and certain MMDx-derived RATs was observed. Tissue transcript clusters were correlated with dd-cfDNA scores, including DSAST, GRIT, HT1, QCMAT, and S4. For individual transcripts, tissue ROBO4 was significantly correlated with dd-cfDNA in both nonrejection and rejection as assessed by MMDx.

Conclusions: Collectively, we have shown substantial diagnostic agreement between dd-cfDNA and MMDx. Furthermore, based on the findings presented, we postulate a common pathway between the release of dd-cfDNA and expression of ROBO4 (a vascular endothelial-specific gene that stabilizes the vasculature) in the setting of antibody-mediated rejection, which may provide a mechanistic rationale for observed elevations in dd-cfDNA in AMR, compared to acute cellular rejection.

Keywords: acute cellular rejection; alograft rejection; antibody-mediated rejection; donor-derived cell-free DNA; gene expression profile; heart transplant; molecular microscopy.