dd-cfDNA Levels Research Articles

Challenging endomyocardial biopsies' gold standard status in rejection screening: a prospective blinded study on cardiovascular magnetic resonance in heart transplant patients

Abstract Background The detection of rejection is crucial for graft survival after heart transplantation. Endomyocardial biopsies (EMBs) serve as the gold standard for rejection surveillance despite its limitations, while cardiac magnetic resonance (CMR), in conjunction with donor-derived cell-free DNA (dd-cfDNA) analysis, holds promise as a non-invasive approach. Purpose In this prospective blinded study, our aim was to evaluate feasibility of CMR for rejection screening, validating it against EMB, dd-cfDNA, and clinical status. Methods We blindly analyzed 250 studies involving CMR, EMB, dd-cfDNA, and clinical data in 58 heart transplant recipients (17 children and 41 adults). Of these 250 studies, 239 (96%) were assessed within 1 to 28 months after transplantation, and 11 studies (4%) 3-14 years post-transplant. In CMR T1- and T2-mapping analyses, acute rejection was defined by T1 or T2 times exceeding the specified thresholds (T1 ≥ 1060 ms, T2 ≥ 55 ms) in at least 2/16 heart segments. EMB findings were graded according to the ISHLT criteria (2005 and 2013), and acute cellular rejection (ACR) grade ≥ 2 or antibody-mediated rejection (AMR) grade ≥ 1 were considered significant. The cutoff for abnormal dd-cfDNA was set at 0.2%. Solely clinical rejection included patients with absent or normal EMB (ACR grade 0-1 and AMR grade 0), but with symptoms or ECG/echocardiographic findings indicative of acute rejection. Results Our study revealed 22 acute rejections, with 15 confirmed through EMB and 7 diagnosed solely based on clinical indicators. Among the EMB-confirmed cases, 3/15 exhibited AMR grade 1, 10/15 demonstrated ACR grade 2 and 2/15 ACR grade 3. CMR identified rejection in 77% (17/22) of cases. Specifically, it successfully identified rejection in 67% (10/15) of EMB-confirmed cases and 100% (7/7) of solely clinically diagnosed cases. Examining the concordance between CMR findings and dd-cfDNA levels, 35% (6/17) of the CMR-identified rejection cases exhibited abnormal dd-cfDNA, while 30% (5/17) showed normal levels. Notably, in one case, despite normal CMR results, both EMB and dd-cfDNA indicated rejection. Conversely, in four instances where EMB indicated acute rejection, both CMR and dd-cfDNA levels were normal. These findings highlight a potential discrepancy in the diagnostic accuracy of EMB, suggesting its tendency to both over- and underdiagnose acute heart transplant rejection. The integration of CMR and dd-cfDNA in the diagnostic process may provide a more comprehensive and reliable assessment of rejection episodes, offering valuable insights for clinical decision-making in heart transplant recipients. Conclusions EMB presents challenges in both under- and overdiagnosing rejection in heart transplant surveillance. A strategy based on CMR, combined with dd-cfDNA analyses, shows promise as a new gold standard for rejection screening.Flowchart

Donor-derived cell-free DNA versus left ventricular global longitudinal strain in noninvasive detection of heart allograft injury

Abstract Introduction Invasive endomyocardial biopsy (EMB) is still considered the gold standard method for monitoring heart transplant (HTx) rejection. However, it is associated with potentially serious complications, and its histopathologic interpretation has high interobserver variability. Thus, noninvasive methods for surveillance of the transplanted organ remains of great interest. The noninvasive donor-derived cell-free DNA is a marker of graft injury which can indicate acute rejection, even before the histopathological diagnosis of rejection detected by EMB. The assay has a high negative predictive value for acute rejection. Left ventricular global longitudinal strain (LV GLS) is an emerging marker of subclinical myocardial injury which plays a crucial role in the evaluation of several cardiac diseases; however, its role in HTx injury has so far been poorly investigated. Purpose We aimed to investigate the efficacy of a local laboratory-run dd-cfDNA assay-based heart transplant rejection surveillance programme, and the prognostic and discriminatory performance of LV GLS for subsequent heart allograft injury. Methods HTx recipients without a history of allograft rejection requiring intensification of immunosuppressive therapy were transitioned from our EMB-based surveillance protocol to dd-cfDNA-based rejection surveillance. We assessed the percentage of dd-cfDNA to total cell-free DNA. Injury cut-off was defined by a dd-cfDNA level ≥0.20%, while the severe injury threshold was at ≥0.35%. LV ejection fraction was calculated using 2D Simpson’s method. To derive LV GLS, we analyzed apical 4-chamber, 2-chamber, and long-axis images by 2D speckle tracking echocardiography. Results A total of 244 dd-cfDNA samples were analyzed from 46 patients in fifteen runs performed monthly between October 2022 and December 2023. The dd-cfDNA fraction remained below the injury cut-off in most patients (81%). There were no missed rejection episodes. 88% of routine EMBs that would have otherwise been performed were safely avoided. Eighteen for-cause EMBs were performed based on dd-cfDNA levels suggesting injury. One EMB verified moderate cellular rejection (ISHLT grade 2R) that required steroid pulse therapy. Two EMBs proved mild cellular rejection, one EMB confirmed mild antibody-mediated rejection, while one EMB proved mixed rejection. Thirteen EMBs found no rejection. Mean LVEF was preserved (57.6%±7.6%). Mean LV GLS was -15.1%±2.5% in the whole cohort, while -15.6%±4.7% in recipients with HTx rejection on indication EMB. There was no significant correlation between dd-cfDNA and LV GLS (n=159). Conclusion The noninvasive dd-cfDNA assay is effective in ruling out acute rejection and safely decreases the necessity of invasive surveillance EMBs after HTx. LV GLS is less sensitive in comparison with the dd-cfDNA assay for detection of myocardial injury in the early stages of graft rejection in HTx recipients at low risk for rejection.

High Intrapatient Tacrolimus Variability and Increased Cell-Free DNA in Kidney Transplant Recipients.

Introduction: An inverse relationship has been identified between tacrolimus serum concentrations and donor-derived cell-free DNA (dd-cfDNA) levels after lung transplant, but limited data exists on this relationship in the kidney transplant population. Project Aim: The purpose of this evaluation was to examine the relationship between high tacrolimus variability and elevated dd-cfDNA levels in kidney and simultaneous pancreas-kidney transplant recipients at a single center. Design: Single-center, retrospective, descriptive comparative evaluation of kidney and pancreas-kidney transplant recipients who received longitudinal ddcfDNA surveillance. Intrapatient tacrolimus variability was assessed using the coefficient of variation (%CV) measured between 1 and 12 months posttransplant. Pediatrics, retransplant or multiorgan transplant recipients, and pregnant recipients were excluded. Results: One hundred fifteen recipients with 518 dd-cfDNA levels and 3028 tacrolimus troughs were assessed. Pancreas-kidney recipients had significantly higher median dd-cfDNA (0.29% vs. 0.18%, P = .034) and were excluded from analysis. Ninety-nine kidney transplant recipients were included for analysis. Recipients with tacrolimus %CV ≥30 (N = 66) had significantly higher median dd-cfDNA than %CV <30 (0.22% vs. 0.17%, P = .031). Tacrolimus %CV ≥30 demonstrated higher median peak dd-cfDNA than %CV <30, though this was not statistically significant (0.36% vs. 0.28%, P = .058). Conclusion: These data demonstrated that high intrapatient tacrolimus variability may be associated with elevated dd-cfDNA in the first year after kidney transplant.

B-234 Evaluating the diagnostic utility of dd-cf-dna in renal allograft surveillance: a single-center perspective

Abstract Background Donor-derived cell-free DNA (dd-cf-DNA) tests offer a non-invasive alternative to biopsy for allograft surveillance in solid organ transplantation. Unlike biopsies, dd-cf-DNA tests are not subject to interpretation bias and have the potential to detect subclinical rejection, which can lead to graft dysfunction and poor outcomes. At our institution, dd-cf-DNA testing is currently offered as a send out test and we sought to evaluate its efficacy in monitoring our post-transplant patients. Methods We retrospectively examined electronic health records of 50 renal transplant patients with dd-cf-DNA (using AlloSure and Prospera assays) between January 1st, 2019, and December 31st, 2022 to assess diagnostic utility of dd-cf-DNA relative to donor-specific antibodies (DSA) and biopsy (all predictors of graft function). Statistical analysis included correlation testing with t-tests. Results Overall, dd-cf-DNA levels correlated with DSA levels (p = 0.0002) and patients with both HLA-class I and II DSA had significantly higher dd-cf-DNA levels (p&amp;lt; 0.05). The Prospera dd-cf-DNA assay appeared to be a better predictor of DSA levels (p = 0.04) than the Allosure dd-cf-DNA assay. Though not statistically significant, there was trend towards an increase in dd-cf-DNA in patient with biopsy-proven graft injury and rejection vs no rejection. Interestingly, dd-cf-DNA levels were significantly elevated in patients with biopsy-proven antibody mediated rejection (ABMR). Because dd-cfDNA levels have been reported to be impacted by sensitizing events including prior transplant, we evaluated and observed levels of dd-cf-DNA to be higher in patients with a history of more than one graft vs single graft recipients (p&amp;lt; 0.0001) and this observation was prominent in the Allosure assay. Conclusions Our findings suggest that dd-cf-DNA testing holds promise as a valuable tool for graft surveillance and early detection of ABMR. The lack of correlation with biopsy-confirmed rejections may be attributed to the dd-cf-DNA assays’ ability to detect rejection events earlier in the disease progression process compared to biopsy. Time course analysis will be beneficial. Additionally, the observed differences between AlloSure and Prospera emphasize the significance of thoroughly evaluating and selecting assays, particularly in multi-transplant recipients. We highlight that our initial analysis is limited due to a small sample size. However, we aim to assess 200 patients by the conclusion of this study.

Clinical Utility of Donor-Derived Cell-Free DNA in Heart Transplant Recipients With Multi-Organ Transplants.

Donor-derived cell-free DNA (dd-cfDNA) has emerged as a reliable, noninvasive method for the surveillance of allograft rejection in heart transplantation (HT) patients, but its utility in multi-organ transplants (MOT) is unknown. We describe our experience using dd-cfDNA in simultaneous MOT recipients. A single-center retrospective review of all HT recipients between 2018 and 2022 that had at least one measurement of dd-cfDNA collected.Patients who had simultaneous MOT were identified and included in this study.Levels of dd-cfDNA were paired with endomyocardial biopsies (EMB) performed within 1 month of blood testing if available. Acute cellular rejection (ACR) was defined as ISHLT (International Society for Heart and Lung Transplantation) grade≥2R. and antibody-mediated rejection (AMR) was defined as pAMR grade > 0.The within-patient variability score of the dd-cfDNA was calculated by the variance/average. The study included 25 multiorgan transplant recipients: 13 heart-kidney (H-K), 8 heart-liver (H-Li), and 4 heart-lung (H-Lu). The median age was 55 years, 44% were female; the median time from HT until the first dd-cfDNA measurement was 4.5 months (IQR 2, 10.5).The median dd-cfDNA level was 0.18% (IQR 0.15%, 0.27%) for H-K, 1.15% (IQR 0.77%, 2.33%) for H-Li, and 0.69% (IQR 0.62%, 1.07%) for H-Lu patients (p < 0.001).Prevalence of positive dd-cfDNA tests (threshold of 0.20%) were 42.2%, 97.3%, and 92.3% in the H-K, H-Li, and H-Lu groups, respectively. The within-patient variability score was highest in the H-Li group (median of 0.45 [IQR 0.29, 0.94]) and lowest in the H-K group (median of 0.09 [IQR 0.06, 0.12]); p = 0.002. No evidence of cardiac ACR or AMR was found. Three patients experienced renal allograft ACR and/or AMR, two patients experienced rejection of the liver allograft, and one patient experienced an episode of AMR-mediated lung rejection. One person in the H-K group experienced an episode of cardiac allograft dysfunction that was not associated with biopsy-confirmed rejection. Dd-cfDNA is chronically elevated in most MOT recipients.There is a high degree of within-patient variability in levels (particularly for H-Li and H-Lu recipients), which may limit the utility of this assay in monitoring MOT recipients.

Donor-derived Cell-free DNA Evaluation in Pediatric Heart Transplant Recipients: A Single-center 12-mo Experience.

Endomyocardial biopsy (EMB) is considered the gold-standard method to diagnose rejection after heart transplantation. However, the many disadvantages and potential complications of this test restrict its routine application, particularly in pediatric patients. Donor-derived cell-free DNA (dd-cfDNA), released by the transplanted heart as result of cellular injury, is emerging as a biomarker of tissue damage involved in ischemia/reperfusion injury and posttransplant rejection. In the present study, we systematically evaluated dd-cfDNA levels in pediatric heart transplant patients coming for follow-up visits to our clinic for 12 mo, with the aim of determining whether dd-cfDNA monitoring could be efficiently applied and integrated into the posttransplant management of rejection in pediatric recipients. Twenty-nine patients were enrolled, and cfDNA was obtained from 158 blood samples collected during posttransplant follow-up. dd-cfDNA% was determined with a droplet-digital polymerase chain reaction assay. EMB scores, donor-specific antibody measurements, and distress marker quantification were correlated with dd-cfDNA, together with echocardiogram information. The percentage of dd-cfDNA increased when EMBs scored positive for rejection (P = 0.0002) and donor-specific antibodies were present (P = 0.0010). N-terminal pro-B-type natriuretic peptide and high-sensitive troponin I elevation were significantly associated with dd-cfDNA release (P = 0.02 and P < 0.0001, respectively), as were reduced isovolumetric relaxation time (P = 0.0031), signs of heart failure (P = 0.0018), and treatment for rejection (P = 0.0017). By determining a positive threshold for rejection at 0.55%, the test had a negative predictive value maximized at 100%. Collectively, results indicate that dd-cfDNA monitoring has a high negative prognostic value, suggesting that in heart transplanted children with dd-cfDNA levels of <0.55% threshold, protocol EMBs may be postponed.

Donor-derived cell-free DNA-based liquid biopsies to determine future kidney transplant rejection.

Donor-derived cell-free DNA (dd-cfDNA) based liquid kidney biopsies have the potential to detect the chances of kidney transplant rejection. Several studies have found that dd-cfDNA can be used to determine the risk of kidney transplant rejection and may correlate with antibody-mediated rejection (ABMR), T cell-mediated rejection (TCMR), and estimated glomerular filtration rate (eGFR). A high concentration of dd-cfDNA in the body fluids may indicate possible transplant rejection since dd-cfDNA is released as a result of apoptotic and necrotic processes initiated by the recipient's immune system. dd-cfDNA assays have advantages over conventional biopsies since they are noninvasive, and therefore, have the potential to provide a safe and reliable biomarker. Different dd-cfDNA levels have been reported above a number of cutoff thresholds: ABMR at 2.45% and TCMR at 1.3%, compared with 0.44% in healthy patients; and eGFR at 2.5%, a decrease of 25% compared with healthy patients. These results indicate the levels of dd-cfDNA that may be used to signal possible kidney rejection. dd-cfDNA assay is a rapid technique, making it particularly useful in emergencies, and further research into its use in the study of kidney rejection should prove beneficial.

P.517: Evaluation of donor-derived cell-free DNA (dd-cfDNA) levels in primary graft dysfunction (PGD) after lung transplantation.

P.517: Evaluation of donor-derived cell-free DNA (dd-cfDNA) levels in primary graft dysfunction (PGD) after lung transplantation.

Donor-derived cell-free DNA predicted allograft rejection and severe microvascular inflammation in kidney transplant recipients.

The aim of this study is to investigate the clinical validity of donor-derived cell-free DNA (dd-cfDNA) in comparison with that of donor specific anti-HLA antibody (DSA) for predicting biopsy-proven rejection (BPR)and severe microvascular inflammation (severe MVI) in kidney transplant recipients (KTRs). In this prospective observational investigation, 64 KTRs who underwent the indicated biopsies were included. Blood samples collected prior to biopsy were tested for dd-cfDNA and DSA. Biopsy specimens were classified by a renal pathologist according to the Banff classification. The predictive performance of dd-cfDNA and DSA for histological allograft diagnosis was assessed. KTRs were categorized into the high and low dd-cfDNA groups based on a level of 0.4%. Eighteen patients (28.1%) had positive DSA at biopsy, exhibiting higher dd-cfDNA levels than the DSA-negative patients. BPR and severe MVI incidences were elevated in the high dd-cfDNA group (BPR: 42.9% vs. 3.4%, P <0.001; severe MVI: 37.1% vs. 3.4%, P = 0.001). Also, elevated glomerulitis and MVI scores were observed in the high dd-cfDNA group. DSA showed the highest predictive value for BPR (AUC = 0.880), whereas dd-cfDNA alone excelled in predicting severe MVI (AUC = 0.855). Combination of DSA and dd-cfDNA (>0.4%) yielded sensitivities of 80.0% and 50.0% with specificities of 90.7% and 88.0% for antibody-mediated rejection and severe MVI detection, respectively. The dd-cfDNA test is a predictive tool for BPR and severe MVI, and it can improve the performance, especially when combined with DSA for BPR.

Role of Donor-derived Cell-free DNA In Predicting Short-term Allograft Health In Liver Transplant Recipients

BackgroundPredicting allograft dysfunction prior to clinical or biochemical evidence remains one of the challenges in transplantation, and a preclinical detection and early management of its cause allows for improved post-transplant outcomes. Donor derived cell-free DNA (ddcfDNA) has been proposed as an important biomarker of allograft injury and has shown to predict dysfunction prior to any biochemical derangements. We aimed to investigate the diagnostic performance of ddcfDNA in detecting and differentiating the causes of early pre-biochemical detection of graft injury and in predicting the short-term outcomes of graft health using a patented protocol and proprietary set of single nucleotide polymorphisms. MethodsBlood samples were collected on defined postoperative days (1-, 3-, 7- and at 3-months) and were analysed through relatively economical patented protocol (TrunomeTM). Biopsy, biochemical tests, and clinical criteria were analysed between various subgroups. ResultOf a total 50 patients, percentage ddcfDNA (%ddcfDNA) levels were significantly elevated in the rejection group (n=8) as compared to the non-rejection group (n= 42; median elevation 12.8% vs 4.3% respectively) with a significant correlation (r = 0.92, p<0.0001). AUC-ROC analysis revealed that the %ddcfDNA levels can predict graft health more precisely when compared to the conventional liver function tests (AUC for %ddcfDNA- 0.86; p<0.001; AUC for AST-0.65, p=0.08; AUC for ALT- 0.75, p<0.01). Moreover, %ddcfDNA levels (with a threshold >10.2%) on post-operative day 7 accurately predicted short-term (3-months) health status of the graft with 93.33% sensitivity, 94.44% specificity, 87.50% positive predictive value, 97.14% negative predictive value and 94.12% accuracy. ConclusionA single time point ddcfDNA on postoperative day 7 accurately predicts graft health and improves risk stratification in the short-term.

Lack of Association Between Donor-Derived Cell-Free DNA and Cardiac Allograft Vasculopathy.

Cardiac allograft vasculopathy (CAV) is a leading cause of death after heart transplantation (HT). We evaluated donor-derived cell-free DNA (dd-cfDNA) as a noninvasive biomarker of CAV development after HT. The INSPIRE registry at the Intermountain Medical Center was queried for stored plasma samples from HT patients with and without CAV. At Stanford University, HT patients with CAV (cases) and without CAV (controls) were enrolled prospectively, and blood samples were collected. All the samples were analyzed for dd-cfDNA using the AlloSure assay (CareDx, Inc.). CAV was defined per the ISHLT 2010 standardized classification system. Univariate associations between patient demographics and clinical characteristics and their CAV grade were tested using chi-square and Wilcoxon rank sum tests. Associations between their dd-cfDNA levels and CAV grades were examined using a nonparametric Kruskal-Wallis test. A total of 69 pts were included, and 101 samples were analyzed for dd-cfDNA. The mean age at sample collection was 58.6±13.7 years; 66.7% of the patients were male, and 81% were White. CAV 0, 1, 2, and 3 were present in 37.6%, 22.8%, 22.8%, and 16.8% of included samples, respectively. The median dd-cfDNA level was 0.13% (0.06, 0.33). The median dd-cfDNA level was not significantly different between CAV (-) and CAV (+): 0.09% (0.05%-0.32%) and 0.15% (0.07%-0.33%), respectively, p=0.25 and with similar results across all CAV grades. In our study, dd-cfDNA levels did not correlate with the presence of CAV and did not differ across CAV grades. As such, dd-cfDNA does not appear to be a reliable noninvasive biomarker for CAV surveillance.

Clinical Utility of the Molecular Microscope Diagnostic System in a Real-World Transplant Cohort: Moving Towards a New Paradigm.

To evaluate the clinical implications of adjunctive molecular gene expression analysis (MMDx ) of biopsy specimens in heart transplant (HT ) recipients with suspected rejection. Histopathological evaluation remains the standard method for rejection diagnosis in HT. However, the wide interobserver variability combined with a relatively common incidence of "biopsy-negative" rejection has raised concerns about the likelihood of false-negative results. MMDx, which uses gene expression to detect early signs of rejection, is a promising test to further refine the assessment of HT rejection. Single-center prospective study of 418 consecutive for-cause endomyocardial biopsies performed between November 2022 and May 2024. Each biopsy was graded based on histology and assessed for rejection patterns using MMDx. MMDx results were deemed positive if borderline or definitive rejection was present. The impact of MMDx results on clinical management was evaluated. Primary outcomes were 1-year survival and graft dysfunction following MMDx-guided clinical management. Secondary outcomes included changes in donor-specific antibodies, MMDx gene transcripts, and donor-derived cell-free DNA (dd-cfDNA) levels. We analyzed 418 molecular samples from 237 unique patients. Histology identified rejection in 32 cases (7.7%), while MMDx identified rejection in 95 cases (22.7%). Notably, in 79 of the 95 cases where MMDx identified rejection, histology results were negative, with the majority of these cases being antibody-mediated rejection (62.1%). Samples with rejection on MMDx were more likely to show a combined elevation of dd-cfDNA and peripheral blood gene expression profiling than those with borderline or negative MMDx results (36.7% vs 28.0% vs 10.3%; p<0.001). MMDx results led to the implementation of specific antirejection protocols or changes in immunosuppression in 20.4% of cases, and in 73.4% of cases where histology was negative and MMDx showed rejection. 1-year survival was better in the positive MMDx group where clinical management was guided by MMDx results (87.0% vs 78.6%; log rank p=0.0017). In our cohort, MMDx results more frequently indicated rejection than histology, often leading to the initiation of antirejection treatment. Intervention guided by positive MMDx results was associated with improved outcomes.

Cell-free DNA for the detection of kidney allograft rejection

Donor-derived cell-free DNA (dd-cfDNA) is an emerging noninvasive biomarker that has the potential to detect allograft injury. The capacity of dd-cfDNA to detect kidney allograft rejection and its added clinical value beyond standard of care patient monitoring is unclear. We enrolled 2,882 kidney allograft recipients from 14 transplantation centers in Europe and the United States in an observational population-based study. The primary analysis included 1,134 patients. Donor-derived cell-free DNA levels strongly correlated with allograft rejection, including antibody-mediated rejection (P < 0.0001), T cell-mediated rejection (P < 0.0001) and mixed rejection (P < 0.0001). In multivariable analysis, circulating dd-cfDNA was significantly associated with allograft rejection (odds ratio 2.275; 95% confidence interval (CI) 1.902–2.739; P < 0.0001) independently of standard of care patient monitoring parameters. The inclusion of dd-cfDNA to a standard of care prediction model showed improved discrimination (area under the curve 0.777 (95% CI 0.741–0.811) to 0.821 (95% CI 0.784–0.852); P = 0.0011) and calibration. These results were confirmed in the external validation cohorts (n = 1,748) including a cohort of African American patients (n = 439). Finally, dd-cfDNA showed high predictive value to detect subclinical rejection in stable patients. Our study provides insights on the potential value of assessing dd-cfDNA, in addition to standard of care monitoring, to improve the detection of allograft rejection. ClinicalTrials.gov registration: NCT05995379.

#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 &amp;lt; 0.001, &amp;lt;0.001, 0.02, 0.01, respectively) as well as in comparison CNI-toxicity (median 10, IQR 6-15; p &amp;lt;0.001, &amp;lt;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.

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 chronic lung allograft dysfunction (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 with 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: 2.78, 95% CI: 1.26-6.22,p = 0.012). The risk remained consistent for the Primary EMI subgroup (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=0.805-0.908, p<0.001). Episodes of EMI in lung transplant recipients are often isolated and may not be detectable with traditional clinical monitoring approaches. EMI is associated with an increased risk of severe CLAD or death, independent of concomitant transplant complications.

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.

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).

Nivolumab + Tacrolimus + Prednisone ± Ipilimumab for Kidney Transplant Recipients With Advanced Cutaneous Cancers.

Cancer-related mortality rates among kidney transplant recipients (KTR) are high, but these patients have largely been excluded from trials of immune checkpoint inhibitors because of immunosuppression and risk of treatment-related allograft loss (TRAL). We conducted a prospective clinical trial testing nivolumab (NIVO) + tacrolimus (TACRO) + prednisone (PRED) ± ipilimumab (IPI) in KTR with advanced cutaneous cancers. Adult KTR with advanced melanoma or basal, cutaneous squamous, or Merkel cell carcinomas were eligible. Immunosuppression was standardized to TACRO (serum trough 2-5 ng/mL) + PRED 5 mg once daily. Patients then received NIVO 480 mg IV once every 4 weeks. The primary composite end point was partial or complete (tumor) response (CR) or stable disease per RECIST v1.1 without allograft loss at 16W. Patients with progressive disease (PD) could receive IPI 1 mg/kg IV + NIVO 3 mg/kg once every 3 weeks × 4 followed by NIVO. Donor-derived cell-free DNA (dd-cfDNA) levels were measured approximately once every 2 weeks as a potential predictor of allograft rejection. Among eight evaluable patients, none met the trial's primary end point. All eight patients experienced PD on NIVO + TACRO + PRED; TRAL occurred in one patient. Six patients then received IPI + NIVO + TACRO + PRED. Best overall responses: two CR (one with TRAL) and four PD (one with TRAL). In total, 7 of 8 pre-NIVO tumor biopsies contained a paucity of infiltrating immune cells. In total, 2 of 5 on-NIVO biopsies demonstrated moderate immune infiltrates; both patients later experienced a CR to IPI + NIVO. In 2 of 3 patients with TRAL, dd-cfDNA elevations occurred 10 and 15 days before increases in serum creatinine. In most KTR with advanced skin cancer, TACRO + PRED provides insufficient allograft protection and compromises immune-mediated tumor regression after administration of NIVO ± IPI. Elevated dd-cfDNA levels can signal treatment-related allograft rejection earlier than rises in serum creatinine.