Donor Specific Allo-Antibody is Significantly Associated with Variability in Donor-Derived Cell-Free DNA Scores in Adult Heart Transplant Recipients

Abstract

<h3>Purpose</h3> In this single-center retrospective pilot study heart transplant (HTx) patients were non-invasively monitored by donor-derived cell-free DNA (dd-cfDNA). We hypothesized that longitudinal dd-cfDNA variability scores correlate with preformed and de novo (dn) donor specific HLA allo-antibody (DSA). <h3>Methods</h3> 72 adult HTx patients with at least 3 dd-cfDNA results were included (AlloSure; CareDx Inc., Brisbane, CA). We determined dd-cfDNA variability (ASV) by standard deviation (SD) of longitudinal dd-cfDNA results, scaled x10 (ASV*10), and DSA by single antigen class I/II and MFI >1000 for HLA-A, B, DR, DQB/A and >2000 for HLA-C and DPB/A. <h3>Results</h3> Age at HTx was 49.1 years (SD 14.3). Study enrollment occurred at 270 days +/-SD 420.2 post-HTx. Biopsy-proven rejection (ACR ≥ 2R and/or pAMR ≥ 1) was detected in 16 (22 %), preformed DSA in 9 (12.5%), dnDSA in 13 (18%) and preformed + dn in 2 (2.7%) patients while 48 (66.7%) were DSA negative. Median time from HTx to dnDSA was 329d (range: 39-827). Including all values, mean ASV*10 was highest in patients with dnDSA (3.03 ± 4.74) compared to those with no DSA (0.65 ± 2.04) or preformed DSA (1.36 ± 3.40, p=0.001; <b>Table 1</b>). Patients who developed dnDSA showed a significant increase of ASV*10 after dnDSA detection (1.50 ± 2.06, p = 0.014), but not before dnDSA detection (1.24 ± 1.49, p=0.380) in comparison to patients with no DSA (0.65 ± 2.04, <b>Table 1</b>). <h3>Conclusion</h3> These findings highlight the value of longitudinal assessment of dd-cfDNA and DSA in HTx recipients. Our results show that increased dd-cfDNA variability is associated with the presence of preformed and dnDSA. Further, ASV*10 is significantly increased after identification of dnDSA, further supporting the mechanistic role of dnDSA in mediating poor outcomes after HTx. Confirmation in larger data sets may further advance the utility of longitudinal non-invasive surveillance using dd-cfDNA and dnDSA in transplant recipients.