Cell-free DNA to detect transplant rejection

National Heart, Lung, And Blood Institute

Investigators

Linked publications, trials & patents

Abstract

Project 1: Cell-free DNA to detect acute rejection. Dr. Agbor led the creation of the Genomic Research Alliance for Transplantation (GRAfT), a consortium of five transplant centers in the DC metropolitan area and NHLBI. He is the principal investigator of the natural history study of heart and lung transplant patients. The GRAfT study recruits patients on the transplant wait list. After transplantation, patients are monitored closely with collection of clinical data and serial samples. Sample collection include plasma, blood cells, and fluid from the transplanted lung. The samples are processed at the study sites and transferred to NHLBI for storage and experimentation. Dr. Agbor leveraged transplant genomic admixture to identify and quantitate donor-derived cell-free DNA (ddcfDNA)as a non-invasive and reliable biomarker of allograft injury. Cell-free DNA are short DNA fragments release when cells die into the circulation. During transplant rejection, allograft cells die and release ddcfDNA into the recipient circulation. Since the donor and recipient has different DNA sequences, ddcfDNA can be quantified in recipients blood as a marker of rejection. Dr. has shown that ddcfDNA is sensitive but non-specific for acute rejection. ddcfDNA also detects rejection earlier, up to 2 to 3 months before biopsy. His lab, the Laboratory of Applied Precision Omics (APO) has defined the test characteristics of ddcfDNA and has established a ddcfDNA algorithm that can be used to monitor patients after transplantation, setting the stage for a clinical utility trial. Additional studies have shown that early post-transplant ddcfDNA levels reliably stratify patients for risk of subsequent chronic rejection and early death. APO has also defined racial disparities in chronic rejection and early death. APO has since developed a 2nd generation cfDNA approach that has applications beyond transplantation, showing good performance at defining COVID-19, pulmonary arterial hypertension outcomes. APO is testing if the 2nd generation test can distinguish the different types of rejection. Project 2: Identifying novel and effective drug targets for rejection. APO showed that 75% of patients with one type of rejection fail to respond to treatment and progress to develop chronic CLAD. APO aims to identify molecular mechanisms of treatment failure and has leveraged the GRAfT biorepository to analyze samples. APO intend to compare patients who respond well to treatment to patients who are non-responders. The preliminary analysis showed distinct molecular mechanisms: complement activating pathways for responders versus antibody-mediated phagocytic pathways that utilize the spleen tyrosine kinase (Syk) as a downstream mediator for non-responders. Syk has FDA-approved inhibitors such as Fostamatinib. APO is initiating a series of studies to test the efficacy of fostamatinib to treat antibody-mediated rejection. In addition, APO will use single-cell multi-omics approaches to validate these findings and identify additional drug targets and then test the clinical utility of these additional treatment. Project 3: Leverage GRAfT consortium for pilot clinical utility studies. The GRAfT is a collaborative with a robust clinical research infrastructure at each center. APO leverages the GRAfT consortium to pilot the clinical utility of novel diagnostic tools or targeted therapies. The first study is the Analysis of Lung Allograft Remote Monitoring (ALARM 1.0). This is completed and results are published. The study included 175 subjects with 350 ddcfDNA tests and demonstrated that monthly cfDNA monitorig instead of bronchoscopy is safe. ddcfDNA demonstrated good performance to detect rejection and infection similar to cohort studies. APO is now setting up the Syk Inhibition in MItigating Lung Allograft Rejection (SIMILAR) trial, a pilot RCT to test the safety and efficacy of a Syk inhibitor Fostamatinib versus placebo as an adjunct therapy for rejection.