Cell-free DNA to detect transplant rejection

National Heart, Lung, And Blood Institute

Investigators

Linked publications & trials

Abstract

**Project 1: Cell-free DNA for Detecting Acute Rejection** Dr. Agbor led the creation of the Genomic Research Alliance for Transplantation (GRAfT), a consortium comprising five transplant centers in the Washington, DC metropolitan area and the National Heart, Lung, and Blood Institute (NHLBI). He serves as the principal investigator for a natural history study of heart and lung transplant patients. The GRAfT study recruits patients on the transplant waitlist, closely monitoring them after transplantation through the collection of clinical data and serial samples, including plasma, blood cells, and fluid from the transplanted lung. These samples are processed at the study sites and then transferred to the NHLBI for storage and experimentation. Dr. Agbor has utilized genomic admixture techniques in transplantation to identify and quantify donor-derived cell-free DNA (ddcfDNA) as a non-invasive and reliable biomarker for allograft injury. Cell-free DNA consists of short DNA fragments released into circulation when cells die. During transplant rejection, allograft cells die and consequently release ddcfDNA into the recipient's bloodstream. Since the donor and recipient have different DNA sequences, ddcfDNA can be quantified in the recipient's blood, serving as a marker for rejection. Dr. Agbor has demonstrated that ddcfDNA is sensitive but not specific for acute rejection, and it can detect rejection as early as 2 to 3 months prior to a biopsy. His lab, the Laboratory of Applied Precision Omics (APO), has defined the test characteristics of ddcfDNA and established an algorithm to monitor patients following transplantation, which sets the stage for a clinical utility trial. Additional studies indicate that early post-transplant levels of ddcfDNA can reliably stratify patients based on their risk of subsequent chronic rejection and early mortality. Furthermore, APO has identified racial disparities concerning chronic rejection and early death. The lab has developed a second-generation cfDNA approach with applications beyond transplantation, showing promising results in defining outcomes for conditions like COVID-19 and pulmonary arterial hypertension. APO is currently testing if the second-generation test can differentiate between various types of rejection. **Project 2: Identifying Novel and Effective Drug Targets for Rejection** APO found that 75% of patients with one type of rejection do not respond to treatment and subsequently progress to develop chronic Chronic Lung Allograft Dysfunction (CLAD). The aim of APO is to uncover the molecular mechanisms behind treatment failure by leveraging the GRAfT biorepository for sample analysis. The plan is to compare patients who respond well to treatment with those who do not. Preliminary analyses have revealed distinct molecular mechanisms: complement-activating pathways are associated with responders, while non-responders exhibit antibody-mediated phagocytic pathways that utilize spleen tyrosine kinase (Syk) as a downstream mediator. Syk has several FDA-approved inhibitors, including Fostamatinib. APO is initiating a series of studies to test the efficacy of Fostamatinib for treating antibody-mediated rejection. Additionally, APO will employ single-cell multi-omics approaches to validate these findings and identify further drug targets, subsequently testing the clinical utility of these new treatments. **Project 3: Leveraging the GRAfT Consortium for Pilot Clinical Utility Studies** The GRAfT consortium offers a collaborative and robust clinical research infrastructure at each center. APO uses the GRAfT consortium to pilot the clinical utility of novel diagnostic tools and targeted therapies. The first study, the Analysis of Lung Allograft Remote Monitoring (ALARM 1.0), has been completed and the results have been published. This study included 175 subjects and involved 350 ddcfDNA tests, demonstrating that monthly cfDNA monitoring is safe and effective in detecting rejection and infection, comparable to cohort studies. APO is now preparing to launch the Syk Inhibition in Mitigating Lung Allograft Rejection (SIMILAR) trial, a pilot randomized controlled trial to evaluate the safety and efficacy of the Syk inhibitor Fostamatinib compared to a placebo as an adjunct therapy for rejection.