Donor-derived Cell-free dd-cfDNA Research Articles

#1658 Association of blood dd-cfDNA levels with Banff scores and histopathological lesions in kidney allograft biopsies: results from an observational trial

Abstract Background and Aims Donor-derived cell-free DNA (dd-cfDNA) is a novel blood biomarker of kidney allograft injury. While primarily studied to discriminate rejection from no rejection, knowledge about its dynamics in other graft pathologies is scarce and merits further investigation. Previous research has highlighted its superior diagnostic performance in detecting ABMR compared to TCMR and borderline changes, however, recent studies have suggested that its increase is not limited to damage due to alloimmune injury. Therefore, we aimed to assess the association between dd-cfDNA release and diverse histopathological patterns as well as its correlation with Banff lesion scores in renal allograft biopsies. Method For this analysis, we identified all dd-cfDNA-paired allograft biopsies from a prospective observational trial of kidney transplant recipients undergoing an indication biopsy with deterioration in graft function, persistence of anti-HLA donor-specific antibodies (DSA), or proteinuria. Dd-cfDNA was collected at the time of allograft biopsy and measured using droplet-digital PCR. Both relative and absolute quantification of dd-cfDNA, with cutoffs of 0.5% and 50cp/ml, respectively, were available for clinical interpretation. All biopsy specimens were examined by a central pathologist blinded to the dd-cfDNA results. Histopathological diagnoses were assigned according to the Banff 2019 classification. Results In total, we examined 125 dd-cfDNA paired biopsies from 110 patients performed at our center between April 2020 and October 2023. Absolute levels of dd-cfDNA were significantly higher in mixed rejection (median 156 cp/mL, IQR 138-176), antibody-mediated rejection (ABMR) (median 63cp/mL, IQR 48-81), DSA-negative microvascular inflammation (DSAnegMVI) (median 74 cp/mL, IQR 35-134), and BK-virus associated nephropathy (BKVAN) (median 168cp/mL, IQR 54-311) in comparison to glomerulonephritis (median 12cp/mL, IQR 8-19; p < 0.001, <0.001, 0.02, 0.01, respectively) as well as in comparison CNI-toxicity (median 10, IQR 6-15; p <0.001, <0.001, 0.004, 0.003, respectively). Additionally, patients with mixed rejection, ABMR, and BKVAN had higher absolute dd-cfDNA levels than patients with IFTA (median 13, IQR 8-16; p 0.004, 0.004, and 0.04, respectively), as well as normal histology (median 7, IQR 7-11, p 0.004, 0.008, 0.03, respectively). Finally, absolute dd-cfDNA levels were higher in patients with mixed rejection than in those with UTI (median 14, IQR 12-16, p = 0.02) (Fig. 1). In the univariable analysis, absolute dd-cfDNA levels were significantly correlated with Banff lesion scores for glomerulitis (g), peritubular capillaritis (ptc), and tubulitis (t). In the multivariable analysis, ptc and t were independently correlated with absolute dd-cfDNA levels. Conclusion Increased donor-derived cell-free DNA is not specific for rejection, but also occurs in alternative injury patterns showing microvascular inflammation and severe tubulointerstitial inflammation, such as DSAnegMVI and BKVAN (BK-virus associated nephropathy). Interestingly, dd-cfDNA levels remain low in the setting of de novo or recurrent glomerulonephritis and CNI-toxicity, which are important differential diagnoses in patients with clinical indication biopsy.

Multi-centre analytical performance verification of an IVD assay to quantify donor-derived cell-free DNA in solid organ transplant recipients.

Donor-derived cell-free DNA (dd-cfDNA) has been widely studied as biomarker for non-invasive allograft rejection monitoring. Earlier rejection detection enables more prompt diagnosis and intervention, ultimately improving patient treatment and outcomes. This multi-centre study aims to verify analytical performance of a next-generation sequencing-based dd-cfDNA assay at end-user environments. Three independent laboratories received the same experimental design and 16 blinded samples to perform cfDNA extraction and the dd-cfDNA assay workflow. dd-cfDNA results were compared between sites and against manufacturer validation to evaluate concordance, reproducibility, repeatability and verify analytical performance. A total of 247 sample libraries were generated across 18 runs, with completion time of <24 h. A 96.0% first pass rate highlighted minimal failures. Overall observed versus expected dd-cfDNA results demonstrated good concordance and a strong positive correlation with linear least squares regression r2 = 0.9989, and high repeatability and reproducibility within and between sites, respectively (p > 0.05). Manufacturer validation established limit of blank 0.18%, limit of detection 0.23% and limit of quantification 0.23%, and results from independent sites verified those limits. Parallel analyses illustrated no significant difference (p = 0.951) between dd-cfDNA results with or without recipient genotype. The dd-cfDNA assay evaluated here has been verified as a reliable method for efficient, reproducible dd-cfDNA quantification in plasma from solid organ transplant recipients without requiring genotyping. Implementation of onsite dd-cfDNA testing at clinical laboratories could facilitate earlier detection of allograft injury, bearing great potential for patient care.

Surveillance with Dual Non-invasive Testing for Acute Cellular Rejection After Heart Transplantation: Outcomes from the Surveillance HeartCare Outcomes Registry (SHORE)

BackgroundMolecular testing with gene expression profiling (GEP) and donor-derived cell-free DNA (dd-cfDNA) is increasingly used in the surveillance for acute cellular rejection (ACR) after heart transplant. However, the performance of dual testing over each test individually has not been established. Further, the impact of dual non-invasive surveillance on clinical decision-making has not been widely investigated. MethodsWe evaluated 2077 subjects from the SHORE registry who were enrolled between 2018 and 2021 and had verified biopsy data, and were categorized as dual negative, GEP positive/dd-cfDNA negative, GEP negative/dd-cfDNA positive, or dual positive. Incidence of ACR and follow-up testing rates for each group were evaluated. Positive likelihood ratios (LR+) were calculated and biopsy rates over time were analyzed. ResultsThe incidence of ACR was 1.5% for dual negative, 1.9% for GEP positive/dd-cfDNA negative, 4.3% for GEP negative/dd-cfDNA positive and 9.2% for dual positive groups. Follow-up biopsies were performed after 8.8% for dual negative, 14.2% for GEP positive/dd-cfDNA negative, 22.8% for GEP negative/dd-cfDNA positive and 35.4% for dual positive results. The LR+ for ACR was 1.37, 2.91 and 3.90 for GEP positive, dd-cfDNA positive and dual positive testing, respectively. From 2018-2021, first-year biopsy rates declined from 5.9 to 5.3 biopsies/patient, and second year from 1.5 to 0.9 biopsies/patient. At two-years, survival was 94.9% and only 2.7% had graft dysfunction. ConclusionsDual molecular testing demonstrated improved performance for ACR surveillance compared to single molecular testing. Use of dual non-invasive testing was associated with lower biopsy rates over time, excellent survival, and low incidence of graft dysfunction.

Extreme elevations of donor-derived cell-free DNA increases the risk of chronic lung allograft dysfunction and death, even without clinical manifestations of disease.

Lung transplant recipients are traditionally monitored with pulmonary function testing (PFT) and lung biopsy to detect post-transplant complications and guide treatment. Plasma donor-derived cell free DNA (dd-cfDNA) is a novel molecular approach of assessing allograft injury, including subclinical allograft dysfunction. The aim of this study was to determine if episodes of extreme molecular injury (EMI) in lung transplant recipients increases the risk of CLAD or death. This multicenter prospective cohort study included 238 lung transplant recipients. Serial plasma samples were collected for dd-cfDNA measurement by shotgun sequencing. EMI was defined as a dd-cfDNA above the third quartile of levels observed for acute rejection (dd-cfDNA level of ≥ 5% occurring after 45 days post-transplant). EMI was categorized as Secondary if associated with co-existing acute rejection, infection or PFT decline; or Primary if not associated to these conditions. EMI developed in 16% of patients at a median 343.5 (IQR: 177.3-535.5) days post-transplant. Over 50% of EMI episodes were classified as Primary. EMI was associated with an increased risk of severe CLAD or death (HR: 2.52, 95% CI: 1.10 - 3.82, p= 0.024). The risk remained consistent for Primary EMI (HR: 2.34, 95% CI 1.18-4.85, p=0.015). Time to first EMI episode was a significant predictor of the likelihood of developing CLAD or death (AUC=0.856, 95% CI =.805-908, p<.001). Episodes of EMI in lung transplant recipients are often isolated and not detectable with traditional clinical monitoring approaches. EMI is associated with an increased risk of severe CLAD or death, independent of concomitant transplant complications.

Donor-derived cell-free DNA, gene expression profile, and acute rejection in donation after circulatory death (DCD) heart transplant recipients

BackgroundAcute rejection (AR) is a leading cause of early morbidity and mortality in heart transplant (HTx) recipients. There is limited data in donor after circulatory death (DCD) HTx recipients where ischemia reperfusion injury may contribute to development of AR and may be detected early with non-invasive biomarkers such as donor-derived cell-free DNA (dd-cfDNA) and gene expression profile (GEP). The goal of this study is to compare dd-cfDNA, GEP and rejection outcomes in DCD and donor after brain death (DBD) HTx recipients. MethodsThis single-center, retrospective study included DCD and DBD HTx recipients from January 2020 to September 2022. Patients were excluded from the study if dd-cfDNA and GEP were not available. The CareDx HeartCare platform was used to obtain dd-cfDNA (AlloSure-Heart) and GEP (AlloMap) with the highest values for each patient recorded at 6 and 12 months. The mean values for these non-invasive markers were compared between DCD and DBD groups. Patients were followed for clinical outcomes, including treated AR, coronary allograft vasculopathy (CAV) and death, through September 2023. ResultsA total of 156 HTx patients were included with 50 DCD and 106 DBD recipients. Baseline characteristics were similar between DCD and DBD recipients including mean age (58.5 years vs 56.9 years, p = 0.48), male sex (82% vs 76%, p = 0.56) and Caucasian race (46% vs 43%, p = 0.78). There were no significant differences in mean AlloSure-Heart at 6 and 12 months between DCD and DBD recipients. AlloMap was significantly lower at 6 months (p = 0.04), but not at 12 months between DCD and DBD recipients. With respect to clinical outcomes at 1 year, there were no significant differences in treated AR (22% vs 14%, p = 0.32), ISHLT grade ≥ 2 CAV (0 vs 4%, p = 0.44) or mortality (2% vs 0%, p = 0.69) between DCD and DBD recipients. ConclusionsIn this single center study, there were no significant differences in mean dd-cfDNA and treated AR at 1 year between DCD and DBD HTx recipients. There was a significant increase in mean GEP at 6 months, but not at 12 months in the DBD cohort. Overall, there does not appear to be clinically significant cardiac allograft injury related to DCD as measured by non-invasive markers. Further work is needed to confirm these findings.

Elevation of Donor-derived Cell-free DNA Before Biopsy-proven Rejection in Kidney Transplant.

Standard-of-care biomarkers for renal allograft rejection are lagging indicators, signaling existing organ injury. This precludes early intervention, when immunological cascades leading to rejection are most susceptible. Donor-derived cell-free DNA (dd-cfDNA) shows promise as an early indicator of rejection, allowing earlier and possibly more effective treatment. This analysis was designed to assess this promise using real-world dd-cfDNA testing evidence. This retrospective analysis of the prospective, observational ProActive registry study (NCT04091984) assessed dd-cfDNA and serum creatinine levels before biopsy in 424 patients with ≥1 dd-cfDNA test (n = 1013) in the 6 mo before biopsy. Of 4667 enrolled patients, 1631 patients had ≥18 mo of follow-up data, of which 424 had a biopsy and were included in this analysis. Twenty-six biopsies showed antibody-mediated rejection (ABMR), 62 showed T cell-mediated rejection, and 336 showed nonrejection; each from a unique patient. dd-cfDNA fractions were significantly elevated 5 mo before ABMR biopsies, and 2 mo before T cell-mediated rejection biopsies, compared with nonrejection biopsies. In contrast, serum creatinine did not discriminate between rejection and nonrejection in advance, or concurrent with biopsy. Among patients with nonrejection biopsies, estimated glomerular filtration rate was significantly lower in cases with ≥2 increased dd-cfDNA results (≥1%), compared with those with 0 or 1 increased dd-cfDNA result. These data indicate that dd-cfDNA is an early indicator of biopsy-proven rejection, especially ABMR, suggesting a greater role for dd-cfDNA in surveillance to identify patients at high risk of ongoing or future rejection, thus requiring closer monitoring, biopsy, or other management changes.

(786) - Donor-Derived Cell-Free DNA (dd cf-DNA) for Non-Invasive Monitoring of Allograft Health After Cardiac Transplant in a Tertiary Care Hospital

(786) - Donor-Derived Cell-Free DNA (dd cf-DNA) for Non-Invasive Monitoring of Allograft Health After Cardiac Transplant in a Tertiary Care Hospital

Tale of two assays: Comparison of modern donor-derived cell-free DNA technologies

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. We retrospectively analyzed 248 consecutive samples that had both dd-cfDNA assays simultaneously performed. 26 biopsy specimens were available within 7 days from dd-cfDNA assays. Both dd-cfDNA assays were correctly suggestive of rejection when biopsy was available. However, discordant classifications were present in 23/248 samples when utilizing respective recommended cutoff values for each assay (0.12% for Allosure and 0.15% for Prospera). Discordance was due to increased classification as abnormal results with Allosure (McNemar’s p=0.004). However, there were no significant differences between assays when identical thresholds of 0.12% or 0.15% were implemented for both assays (McNemar’s, p=NS). We conclude that both dd-cfDNA assays can be utilized interchangeably for surveillance of rejection following heart transplantation.

Use of Donor-derived Cell-free DNA to Inform Tapering of Immunosuppression Therapy in Kidney Transplant Recipients: An Observational Study.

Immunosuppression therapy (IST) is required for allograft survival but can cause significant adverse effects. Donor-derived cell-free DNA (dd-cfDNA) is a validated noninvasive biomarker for active rejection in kidney transplant (KTx). Evidence supporting dd-cfDNA testing use in IST management is limited. In this single-center observational study, dd-cfDNA testing was performed in 21 KTx patients considered good candidates for mycophenolic acid (MPA) reduction. Patients with dd-cfDNA <1% at the first visit (enrollment) had their MPA dosage reduced; those with dd-cfDNA ≥1% had their MPA dosage maintained. Patients were monitored with dd-cfDNA for 6 additional visits. Of 21 patients enrolled in the study, 17 were considered low risk for rejection by dd-cfDNA and underwent MPA reduction; 4 patients were considered high risk for rejection by dd-cfDNA and had their initial MPA dosage maintained. Of the 4 patients considered high risk for rejection by dd-cfDNA, 1 experienced chronic allograft nephropathy and graft loss, and another received an indication biopsy that showed no evidence of rejection. Of the 17 patients considered low risk for rejection by dd-cfDNA, none experienced allograft rejection. dd-cfDNA was used for surveillance in a 6-mo period following MPA reduction; no untoward results were noted. This proof-of-concept study reports the use of dd-cfDNA to directly inform IST management in a cohort of KTx who were candidates for IST reduction.

(348) - Correlation Between Donor-Derived Cell-Free DNA (dd-cfDNA) and Molecular Microscope (MMDx) in Heart Transplant Recipients

(348) - Correlation Between Donor-Derived Cell-Free DNA (dd-cfDNA) and Molecular Microscope (MMDx) in Heart Transplant Recipients

NONINVASIVE DIAGNOSIS OF HEART REJECTION AS A PREDICTOR OF LONG-TERM TRANSPLANT SURVIVAL

Background. Currently, in Kazakhstan, the issue of chronic heart failure is becoming increasingly relevant, with high mortality from the terminal stage of chronic heart failure, especially in patients with III-IV functional class. Heart transplantation represents the "gold" standard of surgical treatment for terminal chronic heart failure, but endomyocardial biopsy, used for monitoring the transplanted heart, is an invasive and inconvenient procedure. Aim of this study is to generate data which can aid in more precise antibody-mediated rejection diagnosis, assisting in distinguishing between antibody-mediated rejectionand acute cellular rejection and helping us determine the appropriate treatment strategy Materials and Methods. This article explores the potential of safe and accurate monitoring of acute transplant rejection using circulating donor-derived cell-free DNA(dd-cfDNA). The study included 40 patients who underwent heart transplantation. Results. It was found that 60% of them had a repeat operation, while 40% had a primary one. Various cardiomyopathies, predominantly dilated and ischemic, were the cause of terminal chronic heart failure. The donor-derived cell-free DNA method demonstrates potential in differentiating T-cell-mediated and antibody-mediated rejection, with different patterns donor-derived cell-free DNA elevation. These differences have high clinical significance for diagnosis and treatment tactics. Conclusion. Despite the prospects of using donor-derived cell-free DNA, further research is needed to establish threshold values and confirm its effectiveness in clinical practice.

Comparing Plasma Donor-derived Cell-free DNA to Gene Expression in Endomyocardial Biopsies in the Trifecta-Heart Study.

Plasma donor-derived cell-free DNA (dd-cfDNA) is used to screen for rejection in heart transplants. We launched the Trifecta-Heart study (ClinicalTrials.gov No. 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 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 No. NCT04239703). We analyzed 137 consecutive dd-cfDNA-EMB pairs from 70 patients. Plasma %dd-cfDNA was measured by the Prospera test (Natera Inc), and gene expression in EMBs was assessed by Molecular Microscope Diagnostic System using machine-learning algorithms to interpret rejection and injury states. Top transcripts correlating with dd-cfDNA were related to genes increased in rejection such as interferon gamma-inducible genes (eg, HLA-DMA) but also with genes induced by injury and expressed in macrophages (eg, SERPINA1 and 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. In this first analysis of 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 clinical management of heart transplant recipients.

Histopathology, mRNA expression profile, and donor-derived cell-free DNA for assessment of rejection in pediatric heart transplantation.

The relationship between histopathologic and molecular ("MMDx"®) assessments of endomyocardial biopsy (EMB) and serum donor-derived cell-free DNA (ddcfDNA) in acute rejection (AR) assessment following pediatric heart transplantation (HT) is unknown. EMB sent for MMDx and histopathology from November 2021 to September 2022 were reviewed. MMDx and histopathology results were compared. DdcfDNA obtained ≤1 week prior to EMB were compared with histopathology and MMDx results. The discrimination of ddcfDNA for AR was assessed using receiver-operating curves. In this study, 177 EMBs were obtained for histopathology and MMDx, 101 had time-matched ddcfDNA values. MMDx and Histopathology displayed moderate agreement for T-cell-mediated rejection (TCMR, Kappa = 0.52, p < .001) and antibody-mediated rejection (ABMR, Kappa = 0.41, p < .001). Discordant results occurred in 24% of cases, most often with ABMR. Compared with no AR, ddcfDNA values were elevated in cases of AR diagnosed by both histopathology and MMDx (p < .01 for all). Additionally, ddcfDNA values were elevated in injury patterns on MMDx, even when AR was not present (p = .01). DdcfDNA displayed excellent discrimination (AUC 0.83) for AR by MMDx and/or histopathology. Using a threshold of ≥0.135%, ddcfDNA had a sensitivity of 90%, specificity of 63%, PPV of 52%, and NPV of 94%. Histopathology and MMDx displayed moderate agreement in diagnosing AR following pediatric HT, with most discrepancies noted in the presence of ABMR. DdcfDNA is elevated with AR, with excellent discrimination and high NPV particularly when utilizing MMDx. A combination of all three tests may be necessary in some cases.

A modern heart transplant rejection surveillance protocol utilizing cell-free DNA: A single-center experience

INTRODUCTIONEndomyocardial biopsy (EMBx) is considered the gold standard for rejection monitoring after heart transplantation; however, it is invasive and histologic interpretation has limitations. Sensitive blood biomarkers including donor-derived cell-free DNA (dd-cfDNA) have emerged to decrease EMBx frequency. METHODSWe retrospectively reviewed data on 237 patients who underwent heart transplantation at our institution. Of these, 125 patients underwent monitoring using dd-cfDNA, combined with a fewer number of EMBx, and 112 patients underwent monitoring using EMBx only. We compared rates of rejection, graft dysfunction, and survival at 1 year. RESULTSMedian age at time of transplant was 59.8 years, and 77.6% were men. In the dd-cfDNA group, there were significantly fewer episodes of EMBx defined ACR (2.5% vs. 18.8%, P<0.001) and treated ACR (4.2% vs. 19.6%, P=0.001). Comparatively, there were more EMBx defined AMR (5% vs. 0.9%) and treated AMR (5% vs. 2.7%) in the dd-cfDNA group. No significant differences were observed in graft dysfunction, presence of donor-specific antibodies, or survival at 1 year. CONCLUSIONSIn conclusion, a modern rejection surveillance protocol utilizing non-invasive testing is safe, led to significantly fewer EMBx, fewer treated rejection episodes, and no difference in survival at 1 year. More AMR episodes identified via dd-cfDNA could lead the way for more accurate diagnostic and treatment decisions.

Sex-specific patterns of donor-derived cell-free DNA in heart transplant rejection: An analysis from the Genomic Research Alliance for Transplantation (GRAfT)

IntroductionNon-invasive methods for surveillance of acute rejection are increasingly used in heart transplantation (HT), including donor-derived cell-free DNA (dd-cfDNA). As other cardiac biomarkers differ by sex, we hypothesized that there may be sex-specific differences in performance of dd-cfDNA for detection of acute rejection. The purpose of the current study was to examine patterns of dd-cfDNA seen in quiescence and acute rejection in males and female transplant recipients. MethodsPatients enrolled in the Genomic Research Alliance for Transplantation (GRAfT) who were ≥18 years at the time of HT were included. Rejection was defined by endomyocardial biopsy with ISHLT acute cellular rejection (ACR) grade ≥2R and/or antibody-mediated rejection ≥ pAMR 1. dd-cfDNA was quantitated using shotgun sequencing. Median dd-cfDNA levels were compared between sexes during quiescence and rejection. The performance of dd-cfDNA by sex was assessed using AUROC. Allograft injury was defined as ddcfDNA ≥0.25%. Results151 unique patients (49 female, 32%) were included in the analysis with 1119 available dd-cfDNA measurements. Baseline characteristics including demographics and comorbidities were not significantly different between sexes. During quiescence, there were no significant sex differences in median dd-cfDNA level (0.04% [IQR 0.00, 0.16] in females vs 0.03% [IQR 0.00, 0.12] in males, p = 0.22). There were no significant sex differences in median dd-cfDNA for ACR (0.33% [0.21, 0.36] in females vs 0.32% [0.21, 1.10] in males, p = 0.57). Overall, median dd-cfDNA levels were higher in AMR than ACR but did not significantly differ by sex (0.50% [IQR 0.18, 0.82] in females vs 0.63% [IQR 0.32, 1.95] in males, p = 0.51). Elevated dd-cfDNA detected ACR/AMR with an AUROC of 0.83 in females and 0.89 in males, p-value for comparison = 0.16. DiscussionThere were no significant sex differences in dd-cfDNA levels during quiescence and rejection. Performance characteristics were similar, suggesting that similar diagnostic thresholds can be used in men and women for rejection surveillance.

The impact of active cytomegalovirus infection on donor-derived cell-free DNA testing in heart transplant recipients.

Little is known about the relationship between cytomegalovirus (CMV) infections and donor-derived cell-free DNA (dd-cfDNA) in heart transplant recipients. In our study, CMV and dd-cfDNA results were prospectively collected on single-organ heart transplant recipients. If the CMV study was positive, a CMV study with dd-cfDNA was repeated 1-3 months later. The primary aim was to compare dd-cfDNA between patients with positive and negative CMV results. Of 44 patients enrolled between August 2022 and April 2023, 12 tested positive for CMV infections, 25 were included as controls, and seven patients with a viral infection without CMV were excluded. Baseline characteristics did not differ significantly between CMV-positive and CMV-negative patients with the exception of a later median time post-transplant in the CMV-positive group (253 days vs. 120 days, p=.03). Dd-cfDNA levels were significantly higher in patients with CMV infections compared to those without (p<.001) with more patients in the CMV positive group showing dd-cfDNA results ≥.12% (75%vs. 8%, p<.001) and ≥.20% (58%vs. 8%, p=.002). Each 1 log10 copy/ml reduction in CMV viral load from visit 1 to visit 2 was associated with a.23% reduction in log10 dd-cfDNA (p=.002). Our findings suggest that active CMV infections may raise dd-cfDNA levels in patients following heart transplantation. Larger studies are needed to validate these preliminary findings.

Detection of donor-derived cell-free DNA in the setting of multiple kidney transplantations.

The routine use of donor-derived cell-free DNA (dd-cfDNA) assays to monitor graft damage in patients after kidney transplantation is being implemented in many transplant centers worldwide. The interpretation of the results can be complicated in the setting of multiple sequential kidney transplantations where accurate donor assignment of the detected dd-cfDNA can be methodologically challenging. We investigated the ability of a new next-generation sequencing (NGS)-based dd-cfDNA assay to accurately identify the source of the detected dd-cfDNA in artificially generated samples as well as clinical samples from 31 patients who had undergone two sequential kidney transplantations. The assay showed a high accuracy in quantifying and correctly assigning dd-cfDNA in our artificially generated chimeric sample experiments over a clinically meaningful quantitative range. In our clinical samples, we were able to detect dd-cfDNA from the first transplanted (nonfunctioning) graft in 20% of the analyzed patients. The amount of dd-cfDNA detected from the first graft was consistently in the range of 0.1%-0.6% and showed a fluctuation over time in patients where we analyzed sequential samples. This is the first report on the use of a dd-cfDNA assay to detect dd-cfDNA from multiple kidney transplants. Our data show that a clinically relevant fraction of the transplanted patients have detectable dd-cfDNA from the first donor graft and that the amount of detected dd-cfDNA is in a range where it could influence clinical decision-making.

Donor-derived cell-free DNA as a diagnostic marker for kidney-allograft rejection: A systematic review and meta-analysis.

Donor-derived cell-free DNA (dd-cfDNA) has emerged as a promising biomarker for detecting graft rejection. This study aimed to evaluate the diagnostic accuracy and clinical value of applying it to kidney transplant rejection. Relevant literature on dd-cfDNA diagnostics in kidney transplant rejection was reviewed from PubMed, Embase, Cochrane Library, and Web of Science databases up to 2023. Data and study characteristics were extracted independently by two researchers, and disagreements were resolved through discussion. Diagnostic accuracy data for any rejection (AR) and antibody-mediated rejection (ABMR) were analyzed separately. Potential heterogeneity was analyzed by subgroup analysis or meta-regression. Funnel plots were used to clarify the presence or absence of publication bias. Nine publications provided data on dd-cfDNA accuracy in diagnosing patients with AR. The pooled sensitivity, specificity, and the area under the receiver operating characteristic (AUROC) curve with 95% confidence intervals (CI) were 0.59 (95% CI, 0.48-0.69), 0.83 (95% CI, 0.76-0.88), and 0.80 (95% CI, 0.76-0.83), respectively. Additionally, 12 studies focused on the diagnostic accuracy of dd-cfDNA for ABMR, showing pooled sensitivity, specificity, and the AUROC curve with 95% CI of 0.81 (95% CI, 0.72-0.88), 0.80 (95% CI, 0.73-0.86), and 0.87 (95% CI, 0.84-0.90), respectively. Study type, age group, and sample size contributed to heterogeneity. In summary, our findings indicate that while plasma dd-cfDNA accuracy in diagnosing patients with AR is limited by significant heterogeneity, it is a valuable biomarker for diagnosing ABMR.

Advancements in Heart Transplantation: Donor-Derived Cell-Free DNA as Next-Generation Biomarker.

Heart failure, particularly in its advanced stages, significantly impacts quality of life. Despite progress in Guideline-Directed Medical Therapy (GDMT) and invasive treatments, heart transplantation (HT) remains the primary option for severe cases. However, complications such as graft rejection present significant challenges that necessitate effective monitoring. Endomyocardial biopsy (EMB) is the gold standard for detecting rejection, but its invasive nature, associated risks, and healthcare costs have shifted interest in non-invasive techniques. Donor-derived cell-free DNA (dd-cfDNA) has gained attention as a promising non-invasive biomarker for monitoring graft rejection. Compared to EMB, dd-cfDNA detects graft rejection early and enables clinicians to adjust immunosuppression promptly. Despite its advantages, dd-cfDNA testing faces challenges, such as the need for specialized technology and potential inaccuracies due to other clinical conditions. Additionally, dd-cfDNA cannot yet differentiate between types of graft rejection, and its effectiveness in chronic rejection remains unclear. Research is ongoing to set precise standards for dd-cfDNA levels, which would enhance its diagnostic accuracy and help in clinical decisions. The article also points to the future of HT monitoring, which may involve combining dd-cfDNA with other biomarkers and integrating artificial intelligence to improve diagnostic capabilities and personalize patient care. Furthermore, it emphasizes both global and racial inequalities in dd-cfDNA testing and the ethical issues related to its use in transplant medicine.

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

IntroductionEndomyocardial 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. MethodsThis is a retrospective observational study of 156 endomyocardial biopsy (EMB) evaluated with traditional microscopy and MMDx. All samples were paired with dd-cfDNA from peripheral blood prior to EMB (up to 9 days). Diagnostic agreement between traditional histopathology, MMDx, and dd-cfDNA (threshold of 0.20%) were compared for assessment of allograft injury. In addition, the relationship between dd-cfDNA and individual RAT expression levels from MMDx was evaluated. ResultsMMDx characterized allograft tissue as no rejection (NR) (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 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 non-rejection and rejection as assessed by MMDx. ConclusionCollectively, 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 (AMR), which may provide a mechanistic rationale for observed elevations in dd-cfDNA in AMR, compared to acute cellular rejection (ACR).